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CRUISE REPORT: A12
(Updated APR 2013)


HIGHLIGHTS

                           CRUISE SUMMARY INFORMATION

          WOCE Section Designation  A12
Expedition designation (ExpoCodes)  06AQ20080210
                  Chief Scientists  Eberhard Fahrbach/AWI      
                             Dates  2008 Feb 10 - 2008 Apr 16 
                              Ship  R/V POLARSTERN
                     Ports of call  Cape Town, South Africa - Punta Arenas, Chile

                                              37° 0'S
             Geographic Boundaries  65° 32'W           12° 45'E
                                              70°34'S

                          Stations  217
      Floats and drifters deployed  15 NEMO, 39 APEX floats deployed
    Moorings deployed or recovered  Grenwich meridian: 9 recovered, 5 deployed
                                    Weddell Sea:       3 recovered, 5 deployed
                                    Kapp Norvegia:     3 recovered, 8 deployed
                                    Sound sources:     5 recovered, 7 deployed
                                    PIES:              5 recovered, 5 deployed

                           Recent Contact Information:

                                Eberhard Fahrbach
Alfred Wegener Institute • Bussestrasse 24 • D-27570 Bremerhaven • (Building F-214) 
                Tel: +49(471)4831-1820 • Fax: +49(471)4831-1797 
                        Email: Eberhard.Fahrbach@awi.de 






The Expedition ANT-XXIV/3 
of the Research Vessel "Polarstern" in 2008









Edited by 
Eberhard Fahrbach and Hein de Baar 
with contributions of the  participants




















Please cite or link this item using the identifier
hdl:10013/epic.34050 or http://hdl.handle.net/10013/epic.34050

ISSN 1866-3192














                                   ANT-XXIV/3
                          10 February - 16 April 2008


                            Cape Town - Punta Arenas
                           Weddell Sea, Drake Passage


                       Chief Scientist: Eberhard Fahrbach



                            Koordinator / Coordinator

                               Eberhard Fahrbach




                          This report is dedicated to
                        Willem Polman and Stefan Winter
     who lost their lives by the helicopter accident at the Neumayer Station
                                on 2 March 2008.



























CONTENTS
		
1.  EXPEDITION ANT-XXIV/3: Fahrtverlauf und Zusammenfassung	

    Itinerary and summary

2.  CASO - (Climate of Antarctica and the Southern Ocean)	

    2.1  Decadal variations of water mass properties in the Atlantic sector
    2.2  Transport variations of the Antarctic Circumpolar  Current
    2.3  Monitoring the ACC transport through Drake Passage
    2.4  Measurements of trace gases: chlorofluorocarbons, helium isotopes & 
         neon
    2.5  Oxygen measurements

3.  GEOTRACES in the International Polar Year during ANT-XXIV/3 expedition
    3.1  Trace elements during ANT-XXIV/3 expedition: NIOZ team
    3.2  Trace elements during ANT-XXIV/3 expedition: IFM-GEOMAR team
    3.3  Isotopes by the AWI-TEAM
    3.4  Nutrient measurements during ANT-XXIV/3
    3.5  Silicate measurements with cyclic voltammetry
    3.6  Intercomparison of GEOTRACES variables with BONUS-GOODHOPE

4.  Dissolved carbon dioxide in the Southern Ocean
    4.1  Deep-ocean carbondioxide chemistry (DIC, TAlk)
    4.2  Surface water carbondioxide chemistry (DIC, pCO2)
    4.3  Intercomparison of carbondioxide variables with BONUS-GOODHOPE
 
5.  Marine biology
    5.1  The significance of viruses for polar marine ecosystem functioning
    5.2  Phytoplankton measurements

6.  Automatic detection of marine mammals 

7.  Weather situation during the cruise leg ANT-XXIV/3 

8.  Acknowledgement 


APPENDIX 

A.1  Beteiligte Institute/Participating Institutes ANT-XXIV/3 

A.2  Fahrteilnehmer/Participants 

A.3  Schiffsbesatzung/Ship's crew 

A.4  Stationsliste /station list PS71


1.  EXPEDITION ANT-XXIV/3: FAHRTVERLAUF UND ZUSAMMENFASSUNG

    Eberhard Fahrbach(1),   (1)AIfred-Wegener-Institut, Bremerhaven
    Hein de Baar(2)         (2)NIOZ


Von Kapstadt zur Neumayer-Station

Die Reise sollte am 6. Februar 2008 in Kapstadt beginnen. Der 
Hafenaufenthalt stand im Zeichen des Besuchs der Bundesministerin für 
Bildung und Forschung Frau Dr. Annette Schavan. Sie kam mit 
südafrikanischen Ministerkollegen, Würdenträgern und Wissenschaftlern 
sowie unseren Kollegen vom französischen Forschungsschiff Marion 
Dufresne zu Gesprächen, einem Workshop und einem gelungenen Empfang an 
Bord. Das Ereignis war sorgfältig vorbereitet worden und die gute 
Stimmung der 150 Gäste war ein sicheres Zeichen für den Erfolg dieser 
Bemühungen.

Der anhaltend stürmische Wind verhinderte, dass ein noch aus stehender 
CO2Container in Kapstadt angelandet werden konnte. Schließlich wurde 
das Schiff mit unserem Container nach Port Elizabeth umgeleitet, und so 
traf er erst in der Nacht zum 10. Februar auf der Polarstern ein. 
Unverzüglich wurde seeklar gemacht und so begann unsere Reise am 10. 
Februar endlich mit dreieinhalb Tagen Verspätung. Die Fahrtroute ist in 
Abb. 1.1 dargestellt.

Als Erstes wurden die Messungen vom fahrenden Schiff aus aufgenommen. 
Der akustische, profilierende Strömungsmesser (Akustischer-Doppler-
Profilstrommesser, ADCP) und der Thermosalinograph lieferten Daten und 
die Pumpen förderten Wasser für Analysen. Entweder durch einen 
Schnorchel im Kiel in das bordeigene Leitungsnetz oder, um besonders 
reines Wasser zu erhalten, aus einem Schleppfisch, der Wasser neben dem 
Schiff einsaugte.

Die erste Station diente zur Aufnahme eines sogenannten PIES (Pressure 
Inverted Echosounder), der an dieser Position verankert war und die 
Schwankungen der Meeresoberfläche und der Schallgeschwindigkeit in der 
Wassersäule erfasst hat.

Nach Abschluss der Aufnahme begann eine Station zur Erprobung eines 
Wasserbeprobungssystems, der sogenannten Ultraclean-CTD, die besonders 
dafür ausgelegt ist, Wasserproben zu nehmen, um die Konzentration des 
im Ozean gelösten Eisens zu bestimmen. Die Messung minimaler 
Konzentrationen von Eisen im Meerwasser stellt unvorstellbare Ansprüche 
an die Probennahme, da das Schiff überwiegend aus Eisen besteht. Um 
diesen Einfluss des Schiffes zu vermeiden, wurde im Niederländischen 
Meeresforschungsinstitut (NIOZ) ein spezieller Probennehmer gebaut. Er 
besteht aus Titan und wird an einem Keviardraht gefiert, um alles Eisen 
im Bereich der Probennahme zu vermeiden. Zur Erfüllung dieser hohen
Anforderungen entstand ein System aus Winde, Stromversorgung und 
ReinraumContainer, das das Arbeitsdeck nahezu ausfüllt. Der Test 
verlief erfolgreich.

Am 11. Februar 2008 kreuzte sich unser Kurs mit dem des norwegischen 
Forschungsschiffes G.O. Sars, das auf dem Weg nach Kapstadt war und 
sein Programm beendet hafte. Zwei deutsche Kollegen waren an Bord. 
Obwohl wir an einem gemeinsamen Programm mit im Ozean verankerten PIES 
arbeiten, musste sich das Treffen auf ein Winken von Schiff zu Schiff, 
dem Blasen der Hörner und dem anschließenden Austausch von Fotos per 
Email beschränken, da wir bei der gegebenen Verzögerung keine weitere 
Zeit verlieren wollten.

Die nächste Teststation galt dem Hauptarbeitsmiftel der Ozeanographen, 
der CTD (Conductivity, Temperature, Depth), die uns die 
Vertikalverteilung von Temperatur, Salzgehalt, Sauerstoff, Trübung und 
Fluoreszenz an Bord anzeigt. Zusätzlich wurde das Strömungsprofil mit 
zwei Akustischen-Doppler-Profilstrommessern (ADCP) erfasst, die an der 
CTD befestigt waren. Auch hier war der Erfolg zu vermelden, so dass die 
Probestation schon für die Forschung verwendbares Wasser und Daten 
lieferte und man zu Routine übergehen konnte. Diese wurde allerdings 
durch das Wetter unterbrochen, da uns ein Tief mit 10 Windstärken 
streifte und unseren Weg nach Süden verzögerte.

Am 15. Februar überquerten wir die ozeanische Polarfront und am 25. 
Februar den 60. Breitengrad. Damit erreichten wir die Antarktis und das 
nördliche Stromband des Weddellwirbels. Dieses großräumige, 
nierenförmige Strömungssystem füllt den gesamten antarktischen Sektor 
des Atlantiks aus. Östlich des Meridians von Greenwich strömt warmes, 
salzreiches Wasser aus dem Antarktischen Zirkumpolarstrom, das 
Zirkumpolare Tiefenwasser, nach Süden. Im Westen fließt in der Tiefe 
das neu gebildete Weddeilmeer-Bodenwasser nach Norden. Im Süden folgt 
der Antarktische Küstenstrom als südlicher Randstrom dieses Wirbels dem 
Verlauf des Kontinentalabhangs und der Schelfeiskante.

Die Lufttemperaturen sanken auf etwas über 0°C mit leichtem Schneefall. 
Der Wind pendelte zwischen 6 und 8 Windstärken hin und her. Zahlreiche 
Eisberge trieben im nördlichen Stromband des Weddellwirbels von der 
Antarktischen Halbinsel in unseren Bereich. Allerdings waren es nur 
stark verwitterte Reste und nicht die für die Antarktis typischen 
Tafeleisberge.

Der Stationsabstand von anfänglich 100 Seemeilen wurde auf 30 Seemeilen 
verringert, da unser Hauptarbeitsgebiet im Weddellwirbel lag. Der 
nördliche Teil des Schnitts wurde von der Marion Dufresne abgedeckt. An 
jeder Station wurde eine CTD-Sonde eingesetzt. An sogenannten 
"Superstationen" kam das ganze Spektrum der Probennahme zum Einsatz. 
Auf dem Meridian von Greenwich führten wir 7 dieser Superstationen 
durch, bei denen in mehrfacher Folge mit dem Kranzwasserschöpfer, dem 
Ultraclean-CTD und den in-situ Pumpen Wasserproben für die 
GEOTRACESProbennahme genommen wurden, was etwa 20 Stunden dauerte.
Die Spurenstoff (GEOTRACES) - Gruppe befasste sich hauptsächlich mit 
der Messung von im Meerwasser gelösten Spurenmetallen. Dazu zählt das 
Eisen, das für den Ablauf biologischer Prozesse von besonderer 
Bedeutung ist. Es wird von allen lebenden Organismen benötigt und damit 
auch von Algen, die wiederum die Grundlage der Nahrungskette im 
antarktischen Ozean darstellen. Allerdings ist Eisen nur in äußerst 
geringen Konzentrationen von etwa einem Hundertstel von einem 
Millionstel Gramm in einem Liter Meerwasser (10 Nanogramm pro Liter = 
10 ng/L = 10(^-8) Gramm pro Liter) vorhanden. Im Gegensatz dazu ist das 
Schiff Polarstern eine unvorstellbare Konzentration von Eisen und die 
Probennahme zur Messung der Eisenkonzentration im Meerwasser benötigt 
einen "ultra-reinen" Probennehmer mit 24 Schöpfern. Wenn dieses Gerät 
zurück an Deck ist, wird es sofort in einen ultrareinen Container 
gebracht, um jede Berührung mit dem Eisen des Schiffs zu vermeiden. 
Damit ist es erstmals möglich, vollständige Vertikalschnitte bis in 5 
Kilometer Tiefe im Südlichen Ozean zu vermessen. Auf dem Meridian von 
Greenwich fanden wir sehr geringe Eisenkonzentrationen von nur 5 ng/L 
im Oberflächenwasser, die auf 30 ng/L in größerer Tiefe zunahmen. Im 
südlichen Teil des Schnittes zwischen der Maudkuppe und der 
Schelfeiskante waren die Werte (sogar) mit 3 ng/L im Oberflächenwasser 
und 20 ng/L in der Tiefe sogar noch geringer.

Kennt man erst einmal die auch geringen Konzentrationen, so stellt sich 
die Frage, woher dieses Eisen überhaupt kommt? Wurde es durch Stürme, 
die Staub aufwirbeln, vom Land ins Meer eingetragen? Alle Böden an Land 
enthalten viel natürliches Eisen. Der Anteil von Eisen in den Böden 
beträgt etwa 4 %. Da Böden auch reichlich Aluminium (Al) enthalten, 
messen wir Aluminium als Nachweis für den Staubeintrag. Die 
Konzentrationen des im Meerwasser gelösten Aluminiums waren auf dem 
Schnitt entlang dem Meridian von Greenwich sehr gering. Es waren die 
geringsten Konzentrationen, die man bisher im Ozean fand. Diese 
geringen Konzentrationen von 6 ng/L im Oberflächenwasser sagen uns, 
dass der Staubbeitrag, wenn es ihn überhaupt gibt, sehr gering ist. 
Daher muss das Eisen also von einer anderen Quelle stammen.

Im Sediment sind die Bedingungen günstiger, das Eisen von den Teilchen 
zu lösen, mit denen es in den Ozean eingebracht wurde. Also könnte dort 
die Quelle des Eisens im Meerwasser liegen. Wir wissen von einem 
anderen Element, Mangan (Mn), dass es ebenfalls in den Sedimenten 
gelöst werden kann. Also nutzen wir Mangan als Hinweis darauf, dass das 
Eisen aus dem Sediment stammt. Aber auch die Konzentrationen des 
gelösten Mangans sind äußerst gering, zwischen 3 ng/L im 
Oberflächenwasser und in etwa 10 ng/L in den tieferen Schichten. Nur 
über den mittelozeanischen Rücken findet man im tiefen Ozean höhere 
Mangan- und Eisenkonzentrationen, die durch unterseeischen Vulkanismus 
hervorgerufen werden. Dies lässt vermuten, der unterseeische 
Vulkanismus könne eine der bedeutendsten Quelle für Eisen in der 
Tiefsee sein. Aber auch weitere Metalle, (wie z. B. Zink) werden 
untersucht. So sind zum Beispiel Zink und Kupfer für Lebewesen von 
größter Bedeutung und auch sie kommen nur in ganz geringen 
Konzentrationen vor.

Auf der Strecke wurden vertikal-profilierenden Driftkörper (Argo-
Floats) ausgelegt. Ein großer Teil der Floats wurden von Stephen Riser 
von der Universität von Washington zur Verfügung gestellt. Sie sollen 
im Antarktischen Zirkumpolarstrom in den Indischen Ozean driften. 
In diesem Gebiet haben wir auch eine Serie von 6 Bodendruckmessern mit nach 
oben gerichteten Echoloten (PIES) aufgenommen und 5 davon wieder 
ausgelegt. Leider ging ein Gerät bei der Aufnahme verloren. Aus den 
Messungen dieser Geräte können die Schwankungen des Antarktischen 
Zirkumpolarstroms abgeleitet werden.

Die Verankerungsarbeiten begannen mit der erfolgreichen Aufnahme von 
drei Verankerungen im Übergangsgebiet zwischen dem Zirkumpolarstrom und 
dem Weddellwirbel, mit denen der Austausch zwischen diesen 
Strömungssystemen erfasst wurde. Leider war aus finanziellen Gründen 
eine Neuauslegung dieser Geräte nicht mehr möglich.


Der Unfall

Am 2. März erreichten wir die Atkabucht am frühen Sonntagmorgen, 
nachdem wir am 28. Februar unser Arbeitsgebiet am Meridian von 
Greenwich verlassen haften. Nach grauen und zum Teil stürmischen Tagen 
wurden wir mit Sonntagswetter im wörtlichsten Sinne empfangen. Alle 
freuten sich darauf, nach Tagen der anstrengenden Stationsroutine, 
einen Tag auf dem Eis mit all den Eindrücken zu genießen, die 
Antarktisforschung so besonders faszinierend machen. Zwar mussten die 
Wissenschaftler sich darauf einstellen, auch bei den Lade- und 
Pumparbeiten mit Hand anzulegen, doch sollte genügend Zeit bleiben, 
sich am Aufenthalt auf dem Eis zu erfreuen.

Als wir um 8:30 Uhr die Nachricht erhielten, dass ein Helikopter beim 
Personentransport zur Neumayer-Station abgestürzt war, verwandelte sich 
Vorfreude und Erwartung in Bestürzung und Trauer. Schnell erreichten 
die Hilfsmannschaften von der Neumayer-Ill-Baustelle und der Neumayer-
Station die Absturzstelle und mussten den Tod eines unserer Kollegen, 
Willem Polman aus dem NIOZ und des Piloten Stefan Winter vermelden. 
Zwei weitere Insassen, Alice Renault und Maarten Klunder waren schwer 
und der Helikopter-Techniker Carsten Möllendorf leicht verletzt. Trotz 
seiner Verletzungen war es Carsten Möllendorf gelungen, die anderen 
Verletzten aus dem Helikopter zu bergen und per Funk Hilfe anzufordern. 
Wir bewundern seine Umsicht und Besonnenheit. Die Verletzten wurden so 
schnell wie möglich mit dem zweiten Helikopter in das Hospital der 
Polarstern gebracht und dort versorgt.

Sofort wurde im AWI ein Krisenstab eingesetzt, der eine umfassende 
Unterstützungsaktion einleitete und die Information der Angehörigen und 
der Öffentlichkeit sowie den Rücktransport der Verletzten und 
Verstorbenen in beispielhafter internationaler Zusammenarbeit 
organisierte.

An Bord haben wir uns am 3. Februar zu einer Trauerfeier auf dem 
Helikopterdeck versammelt und von den beiden Kollegen Abschied 
genommen. Willem Polman und Stefan Winter verloren ihr Leben beim 
schwersten Unfall, den wir während des 25jährigen Einsatzes der 
Polarstern zu beklagen haben. Mit dieser Feier wollten wir
den Angehörigen der Opfer unser tiefes Mitgefühl ausdrücken, uns 
gegenseitig Trost geben, und unsere hohe Wertschätzung der beiden Opfer 
bekunden. Unermesslich sind der Schmerz, der Verlust und die Ängste der 
betroffenen Familien, bei denen wir immer mit unseren Gedanken waren. 
Eine Flut von Beileidsbekundungen traf aus der ganzen Welt an Bord, im 
AWI und im NIOZ ein. Wir möchten uns auch auf diesem Wege für das 
weltweite Mitgefühl bedanken, das uns die Stärke verliehen hat, diese 
schwierige Situation durchzustehen. Wir möchten uns auch bei allen 
bedanken, die dazu beigetragen haben, dass die Verletzten schnell 
gefunden, geborgen und behandelt werden konnten und dass unsere 
verstorbenen Kollegen ihre letzte Reise in die Heimat in Würde antreten 
konnten. Weiterhin möchten wir all denen danken, die in vielfältiger 
Weise dazu beigetragen haben, dass die Verletzten optimal versorgt 
wurden und nach Kapstadt und in die Heimat gebracht wurden. Nur wer vor 
Ort war, kann wirklich empfinden, welche Leistung die 
Stationsmannschaften von Neumayer und der Baustelle, 
Besatzungsmitglieder der Polarstern, Piloten, medizinisches Personal, 
Meteorologen, Logistiker und Organisatoren vollbracht haben, um das 
Ausmaß der Katastrophe zu begrenzen.

Am 4. März nahmen wir noch einmal im kleinsten Kreise der unmittelbar 
Betroffenen an der Unfallstelle Abschied von den Opfern. Die 
Baumannschaft hafte zwei Kreuze am Unfallort errichtet. Als wir uns 
dort zum Stillen Gedenken trafen, erhob sich die Basler BT-67 mit den 
Särgen an Bord über unsere Köpfe hinweg zum Flug nach Novolazarevskaja, 
von wo aus der Weitertransport nach Kapstadt erfolgte. Als 
Abschiedsgruß neigten die Piloten die Tragflächen zu den Kreuzen hin. 
Ein würdigerer Abschied eines Polarforschers in die andere Welt lässt 
sich kaum vorstellen.

Am 5. März erfolgte der Transport der Verletzten nach Kapstadt. Am 
frühen Morgen erschien die Wetterlage hoffnungslos. Es herrschte 
Schneetreiben. Die Verletzten mussten einer Geduldsprobe entgegen 
sehen. Doch dann erreichte uns die Mitteilung der Meteorologen: es 
werde besser und die Basler sei von Novolazarevskaja gestartet. Wir 
bewundern den Mut der Piloten und die Kompetenz der Meteorologen, denn 
es wurde besser. Bei Schneefall startete ein Transport mit 
Pistenbullies vom Schiff zum Flugfeld. Mit Schmerz über die Trennung 
und Freude über die Aussicht, diese bald in Kapstadt und bei ihren 
Verwandten zu wissen, nahmen wir von den Verletzten Abschied. Die 
Piloten nutzten die kurze Phase der Wetterbesserung, landeten, nahmen 
die Verletzten an Bord und starteten im letzten Moment, bevor die 
Bedingungen einen Flug nicht mehr zugelassen hätten.

Als uns der erfolgreiche Start gemeldet wurde, legten wir von der 
Schelfeiskante ab, und nahmen in der Atkabucht die Forschung wieder 
auf. Die Ironie des Schicksals bescherte uns bei unserer Fahrt durch 
die Atkabucht einen sonnigen Nachmittag mit den stimmungsvollen 
Eindrücken, die für die Antarktis typisch sind. Schönheit und Zauber 
standen in unmittelbarer Nähe von Schrecken und Trauer. Der 
entschlossene Wille, unsere Arbeit im Sinne und zum Gedenken an unsere 
umgekommenen Kollegen fortzusetzen, half uns, unseren Schmerz zu 
überwinden und wieder zur Forschungsroutine zurück zu finden.

Unser Aufenthalt an der Station diente der Versorgung. Wir haben vor 
allem Treibstoff und Verpflegung angeliefert. Gleichzeitig haben wir 
aber auch die wertvollen Eiskerne, die an der Kohnen-Station erbohrt 
wurden, gebrauchtes Material und Abfall an Bord genommen. Ferner 
mussten Container an Bord umgestaut werden, um wieder Platz zu schaffen 
und Material zur Verfügung zu haben, das erst während des folgenden 
Teils der Reise benötigt wurde. Dazu mussten Frachtcontainer von der 
Ladeluke auf das Eis gestellt werden, die Luken geöffnet und 
Laborcontainer aus den Laderäumen herausgepackt werden. Nachdem alles 
auf Schliffen auf dem Eis stand, um es aus dem Ladebereich auf dem Eis 
entfernen zu können, wurde es in neuer Folge mitsamt der zusätzlichen 
Fracht wieder herangefahren und eingeladen. Ein Verschiebebahnhof auf 
dem Schelfeis. Gleichzeitig wurde Treibstoff in Tankcontainer 
umgepumpt. Das gute Wetter erleichterte die Arbeiten, die zügig voran 
gingen.

Nach Abschluss der Bergungs- und Ladearbeiten nahmen wir die Einladung 
des Stationsleiters gerne an, die Neumayer-Station zu besuchen und 
einen Eindruck von der Arbeit der Uberwinterer zu gewinnen. Sie 
erklärten geduldig die Eigenschaften und die Funktion der Station. Die 
Verabschiedung der Uberwinterer erfolgte dieses Mal mit einem kurzen 
Innehalten an der Station.


Der Abschluss der Arbeiten am Meridian von Greenwich

Eine längere Phase mit relativ schwachem Wind begünstigte den 
Fortschritt der Arbeiten auf dem Greenwich Meridian. Mit 7 
"Superstationen" im Rahmen des G EOTRACES-Programmes, 25 U ltraclean-
CTD5 und 73 "normalen" CTD-Profilen haben wir alle hydrographischen 
Regionen auf dem Meridian von Greenwich zufriedenstellend mit allen 
geplanten Parametern erfasst. Wir haben 9 Verankerungen aufgenommen und 
5 wieder ausgelegt. Das Netz der vertikal profilierenden Driftkörper 
wurde um 38 Floats erweitert.

Bei der Aufnahme der letzten Verankerung etwa 12 Meilen vor der Kante 
des FimbulSchelfeises wurden wir auf eine besondere Probe gestellt. Als 
wir versuchten mit dem POSIDON IA-System Kontakt zu den akustischen 
Auslösern aufzunehmen, erhielten wir keinerlei Rückmeldung. Also lösten 
wir blind aus und warteten ab. Doch keiner der Auftriebskörper erschien 
an der Oberfläche. Auch der Funkpeiler, der Signale von einem 
Satellitensender empfangen sollte, der an der Spitze der Verankerung 
sitzt, empfing nichts. Wir begannen mit dem Schiff Suchkurse zu fahren 
und schickten den Helikopter los. Kein Erfolg. Als uns klar war, dass 
die Verankerung nicht mehr vor Ort sein konnte, nahmen wir die Arbeiten 
mit CTD und Wasserprobennahme wieder auf und arbeiteten uns weiter nach 
Süden vor. Doch dann kam die große Überraschung von OPTIMARE aus 
Bremerhaven. Dort werden die Signale der Satellitensender Tag und Nacht 
überwacht. Wir erhielten die Meldung, dass der Sender kurz nach der 
Auslösung aufgetaucht sei, allerdings 9 km von der Sollposition 
entfernt. Sofort kehrten wir um, der Helikopter stieg auf und konnte 
wenig später die genaue Position der Verankerung in einem Eisfeld in 
wenigen Seemeilen Entfernung melden. Mit der genauen Position ging es 
dann schnell. Die Verankerung wurde vollständig geborgen. Sie zeigte 
Beschädigungen, die klar erkennen ließen, dass sie von einem Eisberg 
verschleppt worden sein musste. Dadurch lag sie in einer Entfernung von der 
Sollposition, in der unser akustisches Signal zwar stark genug war, um die 
Auslöser zu aktivieren, das schwächere Bestätigungssignal des Auslösers uns 
aber nicht mehr erreichte. Der Satellitensender war so tief in den 
Auftriebskörper hineingedrückt, dass er in Bodennähe durch die 
Eisfelder abgeschattet war. Er konnte aber vom Satelliten mit dem Blick 
von oben erkannt werden. Wir sind glücklich über den guten Ausgang. 
Allerdings sind beim Verschleppen durch den Eisberg am Eisecholot 
solche Schäden aufgetreten, dass die aufgezeichneten Daten verloren 
gingen.

Am 12. März waren die Arbeiten am Meridian von Greenwich beendet und 
wir dampften in Richtung Weddell meer.

Die vorläufige Betrachtung der hydrographischen Aufnahme zeigt, dass 
die Abkühlung des Warmen Tiefenwasser nach einer früheren Erwärmung zu 
Ende ist, und es sich gegenwärtig wieder erwärmt. Es handelt sich also 
um eine dekadische Fluktuation. Wir können jetzt das Verhalten der 
atmosphärischen Antriebskräfte mit dem in den 8üziger Jahren 
vergleichen, um damit eine Erklärung der Antriebsmechanismen dieser 
Veränderungen zu finden. Die Temperatur und der Salzgehalt des 
Weddellmeer-Bodenwassers haben in den letzten drei Jahren weiter 
zugenommen. Damit setzt sich eine Entwicklung, die wir seit der Mitte 
der Neunziger Jahre beobachten, weiter fort und die Frage stellt sich 
noch klarer: Hat die globale Erwärmung die Tiefsee erreicht, oder 
handelt es sich um eine Fluktuation über den Zeitraum von Jahrzehnten? 
Da von unseren australischen Kollegen berichtet wird, dass der 
Salzgehalt des Bodenwassers im Rossmeer und vor dem Adelieland weiter 
abnimmt, fordert auch dieser Gegensatz eine Erklärung, die wir im 
westlichen Weddellmeer gefunden haben.


Im Weddelimeer

Die Eisverhältnisse im östlichen Weddellmeer waren durch eine 
ausgeprägte Meereiszunge geprägt. Da aufgrund der Ereignisse bei der 
Neumayer-Station Zeit eingespart werden musste, wurde der östliche Teil 
des Schnitts von Kapp Norvegia nach Joinville Island aufgegeben. 
Alternativ war geplant, die Zunge nördlich zu umfahren, um durch im 
Vergleich zum Stationsbetrieb zügiges Fahren Zeit zu gewinnen. Doch die 
Aussicht auf sehr schlechtes Wetter führte zur Entscheidung, doch in 
die Zunge einzudringen. Es stellte sich heraus, dass das Eis sehr 
leicht war, und wir so gut vorankamen, dass wir uns am 14. März 
entschieden, nach Süden abzudrehen, um noch einen größeren Teil des 
Schnittes abdecken können. Doch bald wurde das Eis sehr schwer 
befahrbar, so dass wir diesen Plan nur zu einem kleinen Teil umsetzen 
konnten. Der Stationsabstand musste auf 45 sm vergrößert werden. Die 
erste Station auf dem Schnitt erfolgt am 15. März bei 69°22'S 16'21'W.

Am 18. März fand die Beerdigung von Willem Polman und am 19. März die 
Trauerfeier für Stefan Winter staff. Gleichzeitig mit den Feiern an 
Land stellten wir an Bord die Forschungsarbeiten ein und trafen uns zum 
gemeinsamen Gedenken. Auch wenn es schwer fiel, den Schmerz zu 
überwinden, so gingen die Forschungsarbeiten weiter. Die tiefen Lücken,
die die Verstorbenen und die Verletzen in unseren Herzen und bei der 
Arbeit hinterlassen haben, wurden, so gut es ging, überbrückt. So 
wurde aus einem Helikoptertechniker ein Windenfahrer für die 
Ultraclean-CTD. Mit Solidarität und noch weiter verstärkter 
Anstrengung wurde das Programm im Sinne und zur Würdigung der 
Verstorbenen fortgeführt.

Wie auf dem Meridian von Greenwich war das Programm von der Routine des 
Fierens und Hievens der "normalen" und der Ultraclean-CTD und der 
Aufarbeitung des nicht versiegenden Stroms von Probenwasser geprägt. 
Meist gingen die Profile bis zum Meeresboden, häufig wurden aber auch 
kurze Profile (200 bis 300 m) eingefügt, um große Mengen Wasser zu 
Experimenten oder zur Extraktion der untersuchten Spurenstoffe zu 
erhalten. Eine besondere Herausforderung stellten immer wieder die 
Verankerungen dar, die wir aufnahmen und auslegten.

Für unser Programm spielte die Auslegung von Schallquellen eine 
besondere Rolle. Um Messungen im Winter und auch unter dem Eis zu 
bekommen, wurden Driftkörper entwickelt, die in der Tiefe von 800 m 
ihre Bahnen ziehen. Nach jeweils 10 Tagen tauchen sie zuerst auf 2000 m 
Tiefe ab und steigen dann an die Oberfläche auf, wobei sie ein 
Temperatur- und Salzgehaltsprofil messen. Dort angekommen erfahren sie 
mit Satellitennavigation ihren Ort und geben die Messdaten ab. Soweit 
das weltweite Argo-System, in dessen Rahmen etwa 3000 derartiger Floats 
im offenen Ozean unterwegs sind, und zu dem auch wir unseren Beitrag 
leisten. Unter dem Eis funktioniert dieses Verfahren aber nicht, da die 
Floats die Oberfläche nicht erreichen können. Deshalb orientieren sich 
unsere Floats mit Hilfe von Schallquellen und der Laufzeit, der von 
ihnen ausgestrahlten Signale. Befinden sich die Floats unter dem Eis, 
so erkennen sie dies, da sich die Wassertemperatur in der Nähe des 
Gefrierpunkts bewegt, und brechen den Aufstieg an die Oberfläche ab. 
Erreichen sie das nächste Mal offenes Wasser, so geben sie den gesamten 
gemessenen Datensatz ab. Leider mussten wir feststellen, dass zwei von 
den aufgenommenen Schallquellen defekt waren und deshalb ihre Funktion 
nicht erfüllt hatten.

Bei zwei Verankerungen, die wir aufgenommen haben, wurden wir mit einem 
besonderen Phänomen konfrontiert. Um die Verankerungsleine mit den 
Geräten senkrecht im Wasser zu halten, sind Auftriebskörper daran 
befestigt, die in der Tiefsee aus Glaskugeln in Plastikhalterungen 
bestehen. Nun haben wir bei den beiden letzten Verankerungen von den 
tiefsten Auftriebskörpern nur noch mit Glasbrei gefüllte, zerfetzte 
Plastikhüllen vorgefunden. Diese Reste sind eine eindrucksvolle 
Darstellung der Wirkung des Wasserdrucks nach einer Implosion der 
Glaskugeln in über 4500 m Tiefe. Das Rätseln über die Gründe ist 
allerdings noch nicht abgeschlossen.

Im westlichen Teil des Weddellmeeres fanden wir ebenfalls wesentlich 
härtere Eisverhältnisse vor als erwartet. Deshalb wurden wir, was den 
Abschluss des Schnittes anbetrifft auf erhebliche Geduldsproben 
gestellt. Die Eisbedingungen im Weddeilmeer sind in diesem Sommer 
ungewöhnlich hart. Während des Sommers haben sich zwei große Eiszungen 
aus dem südlichen ins nordöstliche und nordwestliche Weddellmeer 
gehalten. Damit wurde ein Trend deutlich bestätigt, gemäß dem das Meereis 
in der Antarktis im Sommer über die letzten Jahrzehnte zugenommen hat. 
Allerdings bedeutet das keine wirkliche Zunahme der Eisbedeckung, sondern 
nur ein geringeres Abschmelzen im Sommer. Im Winter blieb die Eisdecke 
nahezu konstant. Für uns folgte aus dieser Entwicklung nicht nur die Frage 
nach einer Erklärung, sondern sie hafte auch direkte Konsequenzen für den 
Fahrtverlauf. Die herbstliche Eisbildung bescherte uns unerwartet schwere 
Eisverhältnisse, die eher für den Winter typisch sind. Schwere 
Eisverhältnisse bedeuten langsamere Fahrt und damit Zeitverlust im 
Vergleich zu einer Planung, die von mittleren Eisverhältnissen 
ausgegangen war. Dieser Zeitverlust musste durch die Reduktion von 
Stationszeit ausgeglichen werden. Sie erfolgte durch die Vergrößerung 
des Stationsabstands und damit der Fehlergrenzen bei der Abschätzung 
längerfristiger Veränderungen. Trotzdem gelang es, die dominierenden 
Wassermassen so ausreichend zu erfassen, dass der Anschluss an die 
Veränderungen, die wir auf dem Meridian von Greenwich gesehen haften, 
gefunden werden konnte. Der Gehalt von Spurenstoffen ist in bisher 
nicht erreichter Qualität erfasst worden.

Eine besondere Herausforderung stellte die Aufnahme von Verankerungen 
bei schweren Eisverhältnissen dar. Bei der letzten Verankerung, die wir 
im Weddellmeer aufzunehmen hatten, führte das Zusammentreffen von hoher 
Professionalität, die sich mit der Erfahrung von Jahrzehnten (25 Jahre 
Polarstern) gebildet hat und dem Quäntchen Glück, dass man immer 
braucht, um erfolgreich zu sein, zur glücklichen Aufnahme bei fast 100 
% Eisbedeckung. Da die Verankerungen schon drei Jahre lagen und die 
nächste Möglichkeit erst wieder in 3 Jahren bestanden hätte (wenn die 
Batterien der Auslöser erschöpft sein würden), gab es keine wirkliche 
Alternative, als den Versuch zu wagen. Der Erfolg erfüllte uns alle mit 
Freude und auch Stolz. Damit konnten wir die Bilanz ziehen, dass nach 
der erstmaligen Verankerungsdauer von 3 Jahren alle Verankerungen 
wieder aufgenommen werden konnten. Leider ist aber die Gerätetechnik 
noch nicht so ausgreift wie unsere Verankerungstechnik. Trotz 100 % 
Aufnahmerate liegt die Datenrate auf Grund von Geräteausfällen 
niedriger.

Die Auswertung der Daten, die in den verankerten Geräten gespeichert 
wurden, begann schon an Bord. Ein erster Blick zeigte, dass die Folge 
von Erwärmungs- und Abkühlungsvorgängen, die wir in unseren CTD-
Schnitten mit großem zeitlichem Abstand sehen, keine Zufallsergebnisse 
darstellen, sondern dass sie durch die dazwischen liegenden Messungen 
mit verankerten Geräten voll bestätigt wurden. Eine besondere 
Herausforderung wird nun darin bestehen, die extremen Eisverhältnisse 
in Beziehung zu den Wassermasseneigenschaften zu setzen, die neben den 
atmosphärischen Verhältnissen für die Veränderungen verantwortlich sein 
können.

Am 29. März wurden die Arbeiten im Weddellmeer abgeschlossen. Mit 1 
"Superstation" im Rahmen des GEOTRACES-Programmes, 15 ultraclean-CTDs 
und 45 "normalen" CTD-Profilen haben wir das zentrale und das westliche 
Weddellmeer zufriedenstellend mit allen geplanten Parametern erfasst; 
im östlichen Weddellmeer ist leider eine Lücke geblieben. Wir haben 3 
Verankerungen aufgenommen und 8wieder ausgelegt. Das Netz der vertikal 
profilierenden Driftkörper wurde um 16 Floats erweitert.


King George Island und die Drakestraße

Am 30. März erreichten wir King George Island nachdem wir an der 
Nordspitze der Antarktischen Halbinsel noch einmal mit schweren 
Eisverhältnissen zu kämpfen hatten. An der Maxwellbucht im Potter Cove 
liegt die argentinische Station Jubany, der das deutsche Dallmann-Labor 
angeschlossen ist. Von hier und von den Stationen Frei und Artigas aus 
sollte die Übernahme von Fracht stattfinden. Eine Gruppe von sieben 
französischen und einer chilenischen Wissenschaftler/innen wartete bei 
der russischen Station Bellingshausen und 2 koreanische Wissenschaftler 
bei der koreanischen Station King Sejong, um an zu Bord kommen. Ihr 
Interesse bestand in den Arbeiten in der Drake-Passage. Da der Flug von 
King George Island nach Punta Arenas gestrichen worden war, musste die 
Gruppe, die aussteigen wollte, um den Zusteigenden Platz zu machen, bis 
zum Ende der Reise an Bord bleiben. Nach einer sonnigen Anfahrt kam 
aber in der Bucht Nebel auf und eine Zeit des Wartens begann, bis der 
Flugbetrieb endlich möglich war.

Nach mehreren Versuchen bei jeweils kurzfristigen Wetterverbesserungen, 
gelang es am 31. März die neuen Fahrtteilnehmer an Bord zu bringen und 
die Ladung, die bei den Stationen Jubany und Frei auf uns wartete, 
aufzunehmen. Wir mussten aber die Übernahme von Ladung von Artigas 
aufgeben. Der Nebel war zu dicht geworden und eine Wetterbesserung, die 
weitere Flüge ermöglicht hätte, war nicht abzusehen. In der Nacht 
dampften wir in die Drake-Passage und setzten die Aufnahme der 
hydrographischen Bedingungen und der Spurenstoffverteilung fort.

Am 3. April überquerten wir 60° 5 und verließen damit die Antarktis.

Im Vordergrund der Arbeiten in der Drake-Passage stand die Aufnahme und 
Auslegung von franzözisch/koreanischen Verankerungen. Es sollten 10 
Verankerungen aufgenommen und 5 wieder ausgelegt werden. Während die 
ersten beiden Verankerungen der koreanischen Arbeitsgruppe in der 
südlichen Drake-Passage trotz sehr schlechtem Wetters erfolgreich 
aufgenommen werden konnten, hatten wir - trotz wesentlich besserem 
Wetter - große Schwierigkeiten mit den französischen Verankerungen. Bei 
den aufzunehmenden Verankerungen ergaben sich Probleme mit dem 
Auftrieb, der zum Teil dem Druck nicht stand gehalten hatte. Bei den 
meisten von ihnen reichte der verbleibende Auftrieb noch aus. Da sie 
aber zum Teil nur sehr langsam an die Oberfläche kamen, wurde viel 
Geduld gefordert. Beruhigend war, dass ihr Aufstieg mit POSIDONIA 
überwacht werden konnte. Zwei Verankerungen lösten sich zwar vom Boden, 
erreichten aber die Oberfläche nicht. Mit zeitaufwändigen Manövern 
versuchten wir zwar, sie einzufangen, indem wir etwa 5000 m Draht in 
Schleifen über den Grund um sie herum zogen. Aber unsere Bemühungen 
blieben leider ohne Erfolg. Wie immer wir unsere Schleifen legten, was 
bei 6 bis 7 Windstärken nicht einfach war, die driftenden Verankerungen 
konnten uns wieder entweichen, so dass wir beide Dredge-Aktionen 
enttäuscht abbrechen mussten. Die verlorene Zeit konnte nur durch die 
Einschränkung des CTDProgramms ausgeglichen werden. Trotzdem haben wir viel 
Glück gehabt, da sich die Drake-Passage mit dem berüchtigten Kap Hoorn uns 
gegenüber sehr zurückhaltend gezeigt hat. Richtig schlechtes Wetter sollte uns 
erst am 13. April erwischen. Daher beschlossen wir, nicht mehr weiter 
nach Süden zu fahren, um die ausgelassenen CTD-Stationen nachzuholen, 
sondern beendeten bei 5601,07'S 6400,59'W am 13. April mit einer 
letzten CTD das Forschungsprogramm und dampften vor dem Wind in 
Richtung Le-Maire-Straße.

Mit 5 "Superstationen" im Rahmen des GEOTRACES-Programmes, 12 
ultracleanCTD5 und 46 "normalen" CTD-Profilen haben wir die Drake-
Passage nicht ganz zufriedenstellend mit allen geplanten Parametern 
erfasst. Wir haben 8 Verankerungen aufgenommen und 5 wieder ausgelegt. 
Das Netz der vertikal profilierenden Driftkörper wurde um 14 Floats 
erweitert.

Am Mittwoch, dem 16. April 2008 endete die Reise plangemäß in Punta 
Arenas.


Wissenschaftliche Hintergründe

Unsere Reise war vor allem der Untersuchung der ozeanischen Zirkulation 
und den davon abhängenden Stoffkreisläufen mit ihrem Einfluss auf das 
Leben im Meer gewidmet. Das Hauptprogramm der Reise erfolgt im Rahmen 
des Internationalen Polarjahres 2007/2008 (IPY). Es steht unter der 
Schirmherrschaft der ICSU und der WMO und soll durch eine weltweite 
Koordination der Kräfte und die Intensivierung der Aktivitäten zu einer 
quasi-synoptischen Aufnahme der Bedingungen in beiden Polargebiete 
führen, die als Grundlage der Bewertung der gegenwärtig ablaufenden 
Veränderungen dienen wird. Im GEOTRACES-Projekt wurden Spurenstoffe und 
biogeochemische Prozesse untersucht. Das CASO-Projekt (Climate of 
Antarctica and the Southern Ocean) setzte Arbeiten des früheren WECCON-
Projekts (Weddell Sea Convection CONtrol) fort. Es begann mit dem World 
Ocean Circulation Experiment (WOCE) als von 1989 bis 2001 Untersuchungen 
im Weddellmeer ausgeführt wurden, die zum besseren Verständnis 
der Wassermassentransformation und Zirkulation beigetragen 
haben. Diese Messungen wurden anschließend im Climate Variability and 
Predictability (CLIVAR) Programm des World Climate Research Programme 
(WCRP) der UNESCO fortgesetzt. Die Arbeiten in der Drake-Passage 
erfolgten im Rahmen des französischen DRAKE-Projekts, das ebenfalls ein 
Beitrag zum IPYProjekt CASO ist. Die globale Bedeutung der regionalen 
Prozesse wird im IPYProjekt BIAC (Bipolar Atlantic Thermohaline 
Circulation) berücksichtigt. Im Norden schließen die Messungen an die 
Arbeiten des BONUS-GOODHOPE-Projektes an. Die Untersuchungen bei der 
Maudkuppe und im Antarktischen Küstenstrom fanden im Rahmen des von 
SCOR (Scientific Committee of Oceanographic Research) betreuten iAnzone 
Programms statt, das einen Beitrag zum Climate and Cryosphere (CLIC) 
Programm des WCRP liefert und im IPY mit dem Projekt SASSI Synoptic 
Antarctic Shelf Slope Interactions Study vertreten ist. In diesem 
Programm ist besonders die Ausbringung der Upward Looking Sonars (ULS) 
und der Verankerungen an der Küste von Bedeutung. Die ULS sind ein 
Beitrag zum Antarctic Sea Ice Thickness Projects (AnSITP). Das 
Ausbringen der Floats erfolgte im Rahmen des internationalen Argo-Programms, 
das zum Gobal Ocean Observing System (GOOS) beiträgt. Im Rahmen 
der internationalen Programme erfolgt besonders enge Zusammenarbeit mit 
dem Bjerknes Centre in Bergen, Norwegen, und dem British Antarctic Survey 
(BAS), der am Verankerungsprogramm beteiligt ist. Die gesamte Expedition ist 
ein Beitrag zum MARCOPOLI-Programm der Hermann von HelmholtzGemeinschaft 
Deutscher Forschungszentren (HGF).

Ziel der Reise war es, Meeresströmungen und die Temperatur-, 
Salzgehalts- und Spurenstoffverteilungen im Südlichen Ozean zu 
erfassen. Die Absinkbewegungen im Südlichen Ozean stellen den südlichen 
Teil der globalen Umwälzbewegung im Ozean dar. Sie bestimmen seine 
Rolle im Klimageschehen und sind für den Spurenstoffkreislauf von 
Bedeutung. Unsere Messungen werfen die Frage auf, ob die tief reichende 
Umwälzbewegung der ozeanischen Wassermassen in der Antarktis nach einer 
Phase der Schwächung wieder zunimmt. Seit mehr als einem Jahrzehnt 
konnte beobachtet werden, dass die Temperatur in der Tiefsee im 
Weddellmeer kontinuierlich zunahm, was darauf schließen ließ, dass die 
tief reichenden Absinkbewegungen am Rand der Antarktis abgenommen 
haben. Nun sinken die Temperaturen wieder. Diese Entwicklung der 
Wassermassen erfolgt zu einer Zeit, zu der das Meereis in der Antarktis 
im Sommer zunimmt. Dies macht deutlich, dass der Einfluss der globalen 
Erwärmung vor dem Hintergrund jahrzehntelanger Schwankungen nicht 
eindeutig zu identifizieren ist.

Besondere Aufmerksamkeit erregt die Tatsache, dass nach Auswertungen 
von Satellitenaufnahmen durch das NSIDC klar geworden ist, dass der 
Antarktische Sommer 2007/2008 der eisreichste Sommer war, den es seit 
dem Beginn der Satellitenaufnahmen gab. Dieser Trend, der im 
atlantischen Teil des Südlichen Ozeans besonders ausgeprägt ist, steht 
im Gegensatz zur Entwicklung in der Arktis, wo eine deutliche Abnahme 
des Meereises im Sommer zu verzeichnen ist. Die gegensätzlichen 
Entwicklungen in Antarktis und Arktis zu verstehen, ist ein 
wesentliches Ziel dieser Reise. Da sie aber im Laufe von Jahrzehnten 
verlaufen und merkliche räumliche Unterschiede aufweisen, reichen die 
Polarstern-Reisen nicht aus, um sie mit ausreichender Sicherheit zu 
verfolgen. Deshalb muss eine umfassende Erfassung mit Hilfe autonomer 
Mess-Systeme erfolgen, die entweder verankert oder frei treibend sind. 
Sie stellen eine Komponente des Südlichen-OzeanObservations-Systems 
(SOOS) dar, das zur Zeit entwickelt wird. Als Beitrag zu diesem System 
wurden in internationaler Zusammenarbeit 18 verankerte 
Beobachtungsstationen ausgelegt und 20 geborgen. Mit 3 Jahren 
Einsatzdauer stellen die jetzt aufgenommenen Systeme einen Rekord auf. 
Mit der Auslegung von 67 Floats, von denen die im Weddellmeer 
ausgelegten auch unter dem Meereis Daten erfassen können und bis zu 5 
Jahren aktiv bleiben, wurde ein bisher nicht erreichtes Messnetz in 
diesem Teil der Erde erstellt.

Im Internationalen Polarjahr sollten nicht nur neue Erkenntnisse über 
die Rolle der Polargebiete im System Erde gewonnen werden. Es war ein 
zentrales Anliegen, die Öffentlichkeit und insbesondere den Nachwuchs 
in die aktuelle Forschung einzubeziehen und umfassend zu informieren. 
Aus diesem Grund waren zwei Lehrer an Bord. Sie haben aktiv an den 
Forschungsarbeiten teilgenommen und ihren Schülern, Kollegen und auch 
Zeitungen ihre Erlebnisse regelmäßig über Telefon und Internet vermittelt. 
Ihre Erfahrungen werden im Rahmen eines Lehrernetzwerks auch in den 
Unterricht weiterer Schulen und hoffentlich auch in Schulbücher einfließen. 


Abb. 1.1:  Die Fahrtroute der Polarstern während der Reise ANT-XXIV/3 vom
           6. Februar bis zum 16. April 2008
Fig. 1.1:  Cruise track during Polarstern leg ANT-XXIV/3 from 6 February 
           to 16 April 2008



ITINERARY AND SUMMARY


From Cape Town to Neumayer Station

The call to port in Cape Town was marked by a visit of the German 
Federal Minister of Education and Research, Dr. Annette Schavan. She 
came on board with South African Ministerial colleagues, dignitaries 
and scientists in addition to a group of our colleagues from the French 
research vessel Marion Dufresne. During the visit talks were held along 
with a workshop and a reception. The event was carefully prepared and 
the good mood of the 150 guests proved it as a success.

We were supposed to leave on 6 February 2008, but strong winds 
prevented a container for the CO2 programme to arrive Cape Town in 
time. Then, the container ship was diverted to Port Elizabeth and the 
container was finally loaded onto Polarstern in the night to 10 
February. We immediately prepared to depart and our journey could 
finally start on 10 February with three and a half days of delay. The 
cruise track is displayed in Fig. 1.1.

Observations started with instruments which are applied from the moving 
ship with the acoustic profiling current meter (ADCP) and the 
thermosalinograph. Pumps started to inject seawater from a snorkel in 
the keel of the ship into the pipes to the labs for analysis and for 
those who need particularly clean water a fish was used to pump 
seawater from a certain distance onto the ship.

The first stop was dedicated to recover a PIES (Pressure inverted 
echosounder) which moored on the sea floor recorded variations in the 
sea level elevation and the sound velocity in the water column. It was 
the first one of a set of those instruments to be recovered and moored 
again.

Then, a test station for the ultraclean CTD followed. It was brought on 
board by a group from the Netherlands Institute of Sea Research (NIOZ). 
It was supposed to take samples which enable scientists to measure the 
concentration of dissolved iron in the water. It was understood that it 
is highly challenging to measure iron in very faint concentrations on a 
ship which is mainly made out of iron. To avoid interference with the 
ship the NIOZ group had built a special sampling system from titanium 
lowered with a Kevlar wire which avoids any iron parts in the vicinity 
of the sampling process. To meet this requirement a huge device was 
installed which fills up large parts of the deck consisting of a huge 
winch, a power station and a clean room container. The tests were 
successful and proved that the system was mechanically and 
electronically fully operational.

On 11 February we crossed the course of the Norwegian research vessel 
G.O. Sars, which was on its way back to Cape Town from a cruise on which two 
German colleagues participated. In spite of having a common programme with 
PIES in the Southern Ocean, we had to restrict ourselves to waving the 
arms, blowing the horns and a subsequent email exchange of slides taken 
of each of us, since we could not afford to loose further time on our 
way to the South.

The next test station aimed on the main work horse of the physical 
oceanographers, the CTD probe (conductivity, temperature, depth) with 
the rosette water sampler. It is lowered to depth to measure the 
vertical profiles of temperature, salinity, oxygen, transmissivity and 
fluorescence. The data are transmitted on board, displayed and stored. 
In addition a current profile is obtained from the lowered acoustic 
Doppler current profiler (LADCP) which is mounted on the CTD frame. 
Here, as well, the test was performed successfully and water samples 
and data could be used for the programme. Weather slowed us down when a 
low pressure system passed nearby providing us with winds of up to 10 
Bft.

In this northern part of our operation area station work and steaming 
alternated with a distance of almost 100 nm, weather and sea 
permitting. Since the focus of our work was south of the Polar Front 
the distance between the stations decreased to about 30 nm after we 
have passed this point. However, the gaps in the North were closed via 
cooperation with the scientists on the French research vessel Marion 
Dufresne whose focus was on the northern part of the region. Our 
cooperation in the context of the International Polar Year 2007/2008 
resulted in a comprehensive survey of the sea area between South Africa 
and Antarctica.

On 15 February we crossed the Polar Front and reached Antarctica on 25 
February when crossing 60°S. We arrived at our main operation area when 
entering the northern limb of the Weddell gyre, the large-scale bean-
shaped current system which covers the Antarctic sector of the Atlantic 
Ocean. East of the Greenwich meridian warm and salty water from the 
Antarctic Circumpolar Current, the Circumpolar Deep Water, flows to the 
south. In the west newly formed Weddell Sea Bottom Water returns at 
great depth to the north. In the south the Antarctic Coastal Current 
and the Antarctic Slope Current follow as the southern boundary current 
of the gyre the continental slope and the ice shelf front from east to 
west.

Air temperatures decreased to near to 0°C and scattered snowfall 
occurred. The wind fluctuated from 6 to 8 Bft. Significant numbers of 
icebergs were encountered which drifted with the northern limb of the 
Weddell gyre from the Antarctic Peninsula into our operation area. 
However, so far we have only met highly weathered remnants and not the 
impressive table icebergs for which Antarctica is famous.

At super stations a full suite of water sampling devices with at times 
more than 10 casts was operated including the CTD/rosette water 
sampler, the ultraclean sampler and in-situ pumps. They all are needed 
to fulfil the requirements of the GEOTRACES community and take up to 20 
hours per station.

The aim of the GEOTRACES group was to measure the concentration and 
distribution of a variety of trace substances. Dissolved trace metals 
in seawater were the focus of their research. Iron is a very important 
trace metal for biological processes in the Antarctic Ocean. It is essential 
for all living organisms, and thus for the algae also. These algae are the 
basis of the food-chain of the Antarctic region and are in turn 
dependent on the availability of iron. However, iron is only found in 
extremely low concentrations of circa one hundredth of one millionth of 
a gram per litre seawater (10 nanogram per litre = 10 ng/L = 108 gram 
per litre). In contrast Polarstern is a strong ship of steel, iron is 
everywhere on the ship, iron is the ship. Therefore the sampling of 
seawater is done with the special ultraclean frame holding 24 samplers. 
Once this frame is back on the deck, it is immediately placed in its 
own laboratory container, so as to rule out direct contact with the 
iron of the ship. This allows us to collect the first-ever complete 
vertical sections, from surface to circa 5 km deep bottom, in the 
Southern Ocean. Along the Greenwich meridian section we found dissolved 
iron is very low from 5 ng/L in surface waters increasing to 30 ng/L at 
great depth. In the southern part of the Weddell gyre, between Maud 
Rise and the ice shelf of Antarctica, the values are even lower, from 3 
ng/L in surface waters to 20 ng/L in deep waters.

It is one thing to know how much, or how little, iron there is in the 
seawater, but in addition we wonder where this iron has come from. Has 
it been blown into the ocean in dust storms carrying soil dust from 
land to sea? After all, soil on land contains much natural iron, about 
4 percent of soils is iron. Soil also contains much aluminium (Al). 
Therefore we also measure dissolved Al as a source tracer for dust. 
Along the Greenwich meridian the concentration of dissolved aluminium 
in seawater is extremely low, the lowest found thus far in the world 
oceans. Very low levels of 6 ng/L in surface waters tell us that dust 
input from land is very small, if any.

Therefore the dissolved iron must come from somewhere else. In the 
sediments the conditions are better for iron to dissolve from the 
sediment particles and then enter into the bottom waters. So, perhaps 
that is the source of iron to the sea. We know that another element, 
manganese (Mn), can also be dissolved in the sediments. Consequently we 
use manganese as a source tracer for iron coming from below, from the 
bottom sediments. However the concentrations of dissolved manganese 
also are extremely low, from 3 ng/L in surface waters to some times 
about 10 ng/L in deeper layers. Only over the mid-ocean ridge, formed 
by deep-sea volcanism, we find more manganese, and also more iron, in 
the deep waters. Hydrothermal circulation associated with deep-sea 
volcanism, is perhaps the most important source of iron in the ocean 
waters. Others in the team search for their favourite metal. Zinc and 
copper are also necessary for all organisms and occur in very low 
concentrations as well. Overall the dark secrets of the deep unknown 
waters of the Antarctic Ocean are now being discovered for the first 
time.

Deployment of vertically profiling floats (Argo floats) continued to 
add to the world wide network with a significant part of the floats 
being provided by Stephen Riser from the University of Washington. 
These floats were supposed to drift with the Antarctic Circumpolar 
Current into the Indian Ocean. Underway we recovered 6 and redeployed 5 
PIES. One of the instruments was lost upon recovery. These instruments 
measured the fluctuations of the Antarctic Circumpolar Current.

The mooring work started with the successful recovery of three moorings 
in the transition zone from the Antarctic Circumpolar Current to the 
Weddell gyre, which were supposed to measure the exchanges between the 
two current systems. These moorings could not be redeployed because of 
funding reasons.


The accident

On 2 March we reached the Atka Bight in the early hours of Sunday 
morning, after we had left the operation area on the Greenwich meridian 
on 28 February. After greyish and partly stormy days we were greeted 
with Sunday weather in the most literal sense of the word. Everybody 
was excited, after days of tiring station routine, to enjoy one day on 
the ice with all the impressions that renders Antarctic research so 
particularly fascinating. Despite the fact that the scientists had to 
take into account that they must assist with the loading and pumping 
work there should still be sufficient time to enjoy the stay on the 
ice.

However when we received at 8:30 am, the news that a helicopter has 
crashed during the transport of personnel to the Neumayer Station the 
pleasure of anticipation and expectation altered to shock and grief. 
The rescue teams from the Neumayer Ill construction site and the 
Neumayer station quickly arrived at the crash site and had to report 
the deaths of one of our colleagues from NIOZ, Willem Polman and of the 
pilot Stefan Winter. The two other passengers Alice Renault and Maarten 
Klunder were seriously and the helicopter technician Carsten Möllendorf 
was moderately injured. Inspite of his injuries, the helicopter 
technician succeeded in removing the other injured persons from the 
helicopter and radioed for help. We admire his cool head and bravery. 
The injured persons were transported as quickly as possible with the 
second helicopter to the hospital on Polarstern where they were cared 
for.

As soon as the news of the terrible event reached AWI, a crisis centre 
wasestablished at once that was responsible for the organisation and 
coordination of comprehensive support measures necessary for an immediate 
return transport of the casualties, the notification of the next of kin 
and a public statement. Within the shortest period of time an exceptional 
and unparalleled international cooperation was set up providing the 
logistical support for the accident victims' instant trip home via Cape 
Town.

On board we gathered together on 3 March for a memorial on the 
helicopter deck on Monday to bid farewell to our two colleagues. Willem 
Polman and Stefan Winter lost their lives in the most terrible accident 
which ever happened in the 25 years of operation of Polarstern. With 
this ceremony we wanted to express our deepest sympathies to the 
relatives of the victims and comfort each other and express our highest 
appreciation of the two deceased to the whole world. The pain, the loss 
and the fear of the affected families is beyond belief; they are always 
in our thoughts. A flood of condolences arrived on board, at the AWI 
and at the NIOZ from all around the world. With this report, we wish to 
express our thanks for the worldwide sympathy, which provided us with 
the strength to carry on and get through this difficult situation. As 
well we want to thank all those who have contributed so that the 
injured were discovered fast, rescued and taken care of and that our 
deceased colleagues could begin their last journey with dignity. In addition, 
we would like to thank all of those who ensured that the injured receive 
optimal care and could return from Cape Town to their home countries shortly. 
Only those who were at the location know what it was like for the crews of 
the station of Neumayer and the construction site and the crew members of 
Polarstern, pilots, medical personnel, meteorologists, logistical officers, 
and managers to do all what was needed to limit the extent of this disaster.

On 4 March we once again bid farewell with a small group of the most 
closely affected at the place of the accident. The construction team 
had built and placed two crosses at the place of the accident. As we 
held a moment of silence in remembrance, the Basler BT-67 with the 
bodies on board flew overhead on their flight to Novolazarevskaja, from 
where the further transport to Cape Town occurred. As a farewell the 
pilots dipped their wings towards the crosses. It is difficult to 
imagine a more dignified farewell for a Polar researcher leaving for 
another world.

On 5 March the injured were transported to Cape Town. In the early 
morning the weather situation seemed to be hopeless. There was 
continuous snowfall. The injured had to prove further patience. 
However, we then received the message of the meteorologists: it will 
improve and the Basler BT-67 has departed from Novolazarevskaja. We 
admire the courage of the pilots and the skill of the meteorologists 
because weather really improved. With snow still falling the transport 
by the PistenBullies from the ship to the airfield began. With pain 
because of the separation and pleasure of the expectation to know that 
our friends would soon be in Cape Town and with their relatives we bid 
farewell to the injured. The pilots took advantage of the short period 
of better weather, landed, and got the injured on board and started in 
the last moments before the conditions would not permit the flight 
anymore.

When we were informed about the successful takeoff, we left the shelf 
ice front and restarted research in Atka Bight. The irony of fate 
provided us with a sunny afternoon with glorious impressions that are 
typical for Antarctica during out travel across Atka Bight. It is 
strange to think that beauty and enchantment could so closely follow 
horror and grief. However, the decided will to continue our work in the 
spirit and in remembrance of our deceased colleagues, helped us, to 
overcome our pain and to return to the routine of research.

Our stay at the Station was aimed at supply; we mainly had to supply 
fuel and food. Additionally, the valuable ice cores, which were drilled 
at the Kohnen Station, used material and garbage, came on board. 
Furthermore containers had to be rearranged, to provide space and 
material, which was used during the next part of the cruise. For this 
purpose, freight containers had to be moved from the hatch onto the 
ice, the hatches then had to be opened and lab containers had to be 
offloaded. Once all these containers were on sledges on the ice, to 
remove them from the loading area, they were, together with the 
additional freight containers, then carried back and reloaded in a new 
sequence. A shunting yard on the shelf ice. Simultaneously, fuel was 
pumped into the tank containers. The good weather facilitated the work.
After the end of the rescue and loading operation we were pleased to 
accept the invitation of the Station leader to visit the Neumayer 
Station and to get an impression of the work of the over wintering 
team. Patiently they explained the properties and function of the 
station. The farewell of the over wintering team occurred this time 
only with a short break at the station.


The completion of the work on the Greenwich meridian

The work on the Greenwich meridian was determined by an alternating 
sequence of casts with the oceanographic and the ultraclean CTD every 
30 nautical miles. Slowly the hydrographic structure of the Weddell 
gyre appeared in our observations, which we had crossed until the time 
of leaving to the Neumayer Station up to the foot area of Maud Rise at 
65°30'S. A longer phase with relatively weak winds was favourable to 
this progress. We completed 7 "Super stations" in the context of the 
GEOTRACESProgramme, 25 ultraclean CTD5 and 73 normal CTD stations to 
cover all hydrographic regions on the Greenwich meridian with all the 
relevant parameters. We have recovered 9 moorings and redeployed 5 of 
them. Two sound sources were recovered and redeployed. The grid of 
vertically profiling floats was extended by 38 and these drifted under 
the sea ice of the forthcoming autumns and winters.

At the last mooring at about 12 nm north of the edge of the Fimbul Ice 
Shelf, we encountered a new challenge. When we tried to interrogate the 
acoustic releases with the POSIDONIA system on board Polarstern no 
reply was received. So we released blindly and waited for the mooring 
to show up at the surface. However no float was sighted and no signal 
was detected with the radio receiver on board from the satellite 
transmitter, which is mounted on the uppermost part of the mooring. We 
started to search with the ship and with the helicopter, but with no 
result. When we were sure that the mooring was not longer at its 
position, we stopped searching and resumed water sampling stations 
towards the ice shelf edge. However, shortly after, we were surprised 
by a message from OPTIMARE in Bremerhaven who are surveying for us the 
satellite transmitters of the moorings. They informed us that the 
transmitter had reached the surface shortly after the release signal, 
though 9 km away from the expected position. We turned immediately 
towards the indicated position, the helicopter started again and was 
able to identify the mooring in an ice field in a few miles distance. 
With this information from the helicopter it was easily possible to 
approach the mooring with the ship and to recover it quickly. It had 
damages which clearly indicated that it was removed by an iceberg to a 
position which was still within the reach of the POSIDONIA transmitter 
on board to receive the release command, but too far distant for the 
reply from the less powerful releaser to be received on board. The 
satellite beacon was pushed by the iceberg so deep into the float 
assembly that it was hidden for the quasi horizontal view from a 
distance on the ship, but still visible to the satellite which was on 
top of it. We were glad about the happy end of the recovery. However, 
the upward looking sonar was damaged by the iceberg so that the 
recorded data were lost. Still, it is a great success that all moorings 
on the Greenwich meridian were recovered after the first 3-year-mooring
period, which proves that our mooring technology has reached a standard 
which allows us to plan such long deployment periods in future.

Despite the fact that the data requires comprehensive processing and 
calibration work, the quality of our instruments is so high, that a 
first look on the preliminary data from the hydrographic survey 
indicated that the cooling of the Warm Deep Water which was observed 
since the mid 9üties has come to a halt. Together with the observation 
of an earlier warming until the mid 90ties this suggests that decadal 
fluctuations dominate the variability. Now we can compare the 
atmospheric forcing during the last years with the one in the early 
nineties to better understand the forcing mechanism of the 
fluctuations. The temperature and the salinity of the Weddell Sea 
Bottom Water increased further during the last three years. This 
observation provides evidence of the evolution that we have followed 
since the mid 90s and raised the question even clearer: did global 
warming reach the deep sea or is it only a fluctuation on a timescale 
of decades. Because our Australian colleagues report that the salinity 
of the bottom water in the Ross Sea and off Adelie Land keeps on 
decreasing, this regional contrast requires an explanation to which we 
obtained a hint from the data which were obtained in the western 
Weddell Sea. There the Weddell Sea Bottom Water descends into the deep 
sea.

On 12 March the work on the Greenwich meridian was terminated and we 
steamed towards the Weddell Sea.


In the Weddell Sea

The sea ice conditions in the eastern Weddell Sea were determined by a 
pronounced tongue of sea ice emerging from the South. Since we needed 
to save time due to the events at the Neumayer Station, we omitted the 
eastern part of the transect from Kapp Norvegia to Joinville Island. As 
an alternative it was planned to circumnavigate the ice tongue in the 
North to gain by easier conditions and omitting station work the 
required time. However, the forecast of bad weather lead us to the 
decision to enter the ice. It appeared that the ice was rather easy to 
break and we proceeded so fast that we decided on 14 March to turn 
further to the south to be able to begin with the section further to 
the southeast. However the ice conditions became much more serious and 
this plan was only partially successful. We had to increase the station 
distance to 45 nm. The first station on the transect occurred on 15 
March at 69°22'S 16°21'W.

On 18 March the funeral of Willem Polman took place and on 19 March the 
obsequies for Stefan Winter. Simultaneously with the ceremonies on land 
we stopped the work on board and came together for a commemoration. In 
the solemn company of our ceremonies we were with our thoughts near to 
the deceased and their families. Even if it was hard for us to overcome 
our pain, the work on board had to go on. The deep gaps which are left 
by the deceased and injured colleagues in our hearts and at work have 
to be bridged as adequately as possible. In this sense a helicopter 
technician became a winch driver for the ultraclean CTD. With 
solidarity and even more enhanced efforts we continued the programme 
in the sense and as an appreciation of the victims.

As on the Greenwich meridian, the rhythm of the programme was given by 
the sequence of lowering and hoisting of the "normal" and ultraclean 
CTD and the processing of the never ending flow of sampled water. Most 
of the profiles reached to the sea bottom, but frequently shallow casts 
(200 to 300 m) were needed to provide large quantities of water for 
experiments or for extraction of trace substances to be sampled. The 
moorings which we recovered and deployed were always a particular 
challenge.

In our programme the deployment of sound sources is of particular 
interest. To obtain measurements in the winter and under the ice, 
floats were developed which drift at 800 m depths. Once every 10 days 
they descend first to 2000 m depth and then return to the surface. If 
there, they are informed of their position and they transfer the 
measured data by satellites. So far, this is the global Argo system, in 
the context of which about 3,000 such floats operate in the open ocean 
and to which we are contributing. However, under the ice this procedure 
does not work because the floats are not able to reach the surface. For 
this reason our floats are located by means of the sound sources and 
the travel times of the signals they transmit. They recognize that they 
are under the ice because the near surface water temperature is close 
to the freezing point. Then they stop their ascent and return to depth 
again. When they reach open water again, they transmit the full 
recorded data set.

In two moorings we have recovered, we encountered a particular 
phenomenon. The moorings contain buoyancy elements (floats) which are 
supposed to keep the mooring wire upright in the water column. They 
consist of glass spheres in plastic housings. In the two last moorings 
which we recovered we found only remnants of the deepest floats which 
consisted of the smashed plastic housings which contained sand like 
glass flour. Those remnants are an impressive demonstration of the 
impact of the implosion of a glass sphere in about 4,500 m water depth. 
The discussion on the potential causes is not yet finished.

A special challenge is the recovery of moorings under heavy ice 
conditions. At the last mooring we were due to recover in the Weddell 
Sea, the great skill built up during decades of experience (25 years 
Polarstern) and the grain of luck which is always required to be 
successful, resulted in the recovery at almost 100 % in ice cover. 
Since the mooring had already been in place for three years and the 
next opportunity for recovery would be three years later (when the 
batteries of the releases will be most likely exhausted) there was no 
alternative but to give it a try. The success fills our hearts with joy 
and pride. Now we can summarize that after our first deployment period 
of three years, we were able to recover all moorings. Unfortunately the 
instruments technology is not as far developed as our mooring 
technology. Therefore in spite of a 100% recovery rate, we did not 
achieve a 100% data rate.

The evaluation of the data stored in the moored instruments has already 
begun on board. A first glance showed evidence that the sequence of 
longer term cooling and warming events detected in the CTD transect 
repeated in large time intervals were confirmed by the time series 
from the moored instruments. A particular challenge will now be to find 
out if there is a relationship between the extreme ice conditions and 
the water mass properties that together with the atmospheric conditions 
could result in such changes.

To finalize the transect across the Weddell Sea, we needed a lot of 
patience since the sea ice conditions in the Weddell Sea were extreme. 
Over the summer two large ice tongues stretched from the southern to 
the northeastern and the northwestern Weddell Sea. This wider than 
normal ice extent is consistent with a trend visible in the time series 
of NSIDC derived from satellite images of increasing sea ice extent in 
summer during the last decades. However, this does not mean a real 
increase but only a weaker melting in summer because the winter sea 
extent remained basically constant. For us, this situation was not only 
a challenge to be explained but it had direct consequences on the 
cruise. The onset of ice formation in autumn gave rise to unexpected 
heavy ice conditions very similar to winter conditions. Heavy ice 
resulted in lower speed and less station time available, as the 
original plan was based on mean sea ice conditions. The loss of time 
had to be compensated through reduction of station times by increasing 
the station distances. Increasing station distance increases the 
uncertainty of the estimates of the intensity of variations. In spite 
of the restrictions, it was possible to probe the relevant water masses 
sufficiently to detect the correlation of long-term variations in the 
Weddell Sea and those at the Greenwich meridian. The concentrations of 
trace substances were measured in an unprecedented manner.

In the Weddell Sea we completed 1 "Super station" in the context of the 
GEOTRACES-Programme, 15 ultraclean CTD5 and 45 normal CTD stations 
which covered the central and the western part. We have recovered 3 
moorings and redeployed 8 of them. Three sound sources were recovered 
and 4 deployed. Unfortunately we had to take note that two of the 
recovered sound sources had failed. The grid of vertically profiling 
floats was extended by 16 and these will now drift under the sea ice of 
the forthcoming autumns and winters.


King George Island and Drake Passage

On 30 March we arrived at King George Island after having crossed 
serious ice conditions north of Joinville Island. The German Dallmann-
Labor is run in cooperation at the Argentinean station of Jubany, 
located at Maxwell Bay on Potter Cove. We were supposed to take freight 
on board, both here and from the stations Frei and Artigas. A group of 
seven French and one Chilean scientist were waiting at the Russian 
station Bellingshausen and two Korean scientists were waiting at the 
Korean station King Sejong to come on board for the rest of the cruise. 
They are interested in investigations in Drake Passage. Since the 
flight from King George Island to Punta Arenas was cancelled, the group 
who was supposed to return from there had to stay on board until the 
end of the cruise. After a sunny start in the morning the bay was 
immersed in fog and we had to wait until flight conditions would 
prevail for the ship's helicopter to take on board the new scientists 
and to transfer some equipment as well.

On 31 March we left King George Island with a new French/Korean group 
on board. In addition it was possible to load material from Jubany and 
Frei stations. However the bad weather conditions, which showed no hope 
of improvement, forced us to give up our final task of loading material 
from Artigas. Dense fog prevented any further flights for an 
unforeseeable future. During the night, we steamed to Drake Passage 
where an intensive mooring programme took place in addition to the 
continuation of our measurements of water mass properties and 
concentration of trace substances.

The work was focussed on the French/Korean mooring programme. We 
intended to recover 10 moorings and redeploy 5 of them. The first two 
moorings of the Korean group in the southern Drake Passage could be 
recovered in spite of the unfavourable weather conditions with no 
problems. Unfortunately there was a problem with the flotation of the 
following moorings we needed to recover. Most of them had still enough 
buoyancy to ascend to the surface. However, some of them did so at a 
rather slow rate. In spite of the fact that they could be monitored by 
POSIDONIA, this required a lot of patience. Two of the moorings 
ascended but did not reach the surface. With time consuming operations 
we tried to dredge them, by paying out about 5000 m of wire which we 
towed in loops around them. Still, our efforts were not successful. No 
matter which way we placed our loops (which was not easy with 6 to 7 
Bft) the moorings escaped and, disappointed, we had to give up the 
recovery.

In Drake Passage we completed 5 "Super stations" in the context of the 
GEOTRACES-Programme, 12 ultraclean CTD5 and 46 normal CTD stations. We 
have recovered 8 moorings and redeployed 5 of them. The grid of 
vertically profiling floats was extended by 14. The time lost to the 
problems with the moorings had to be regained by the reduction of the 
CTD work which resulted in a coarser resolution. Still we were lucky 
because Drake Passage with famous Cape Hoorn did not show us its most 
uncomfortable side. Really bad weather only reached us only at the end 
of the mooring work when we returned to the south to fill in omitted 
CTD stations. To avoid the bad weather the last CTD station occurred at 
56°1.07'S 64°0.59'W on 13 April 2008. When the bad weather arrived we 
were already steaming towards Le Maire Strait with the wind at our 
back.

On 3 April, we had left Antarctica, when we passed 60°S. On 16 April, 
the cruise ended according to the plan in Punta Arenas.


Scientific background

Our cruise was mainly dedicated to the investigation of the oceanic 
circulation and the biogeochemical processes with their influence on 
life that depends on them. The main programmes occurred in the context 
of the International Polar Year 2007/2008 (IPY). The IPY was 
established under the auspices of ICSU and WMO. It aims to coordinate 
forces globally to achieve a quasi-synoptic survey of the conditions in 
both polar areas to obtain a benchmark for future changes. In the 
GEOTRACES project the role of traces substances in the context of 
biogeochemical cycles is investigated. The CASO project (Climate of 
Antarctica and the Southern Ocean) takes up work which had started in 
the WECCON project (Weddell Sea Convection CONtrol). It aims to investigate 
processes which occur in the Atlantic Sector of the Southern Ocean and 
Drake Passage in cooperation with the Bjerknes Centre for Climate Research 
in Bergen, Norway and the British Antarctic Survey (BAS). In the framework 
of iAnZone, a programme associated to SCOR (Scientific Committee of 
Oceanographic Research) and its IPY SASSI project (Synoptic Antarctic Shelf 
Slope Interactions Study) observation occurred in the area of Maud Rise and 
the Antarctic Coastal Current. The observations occurred jointly with the 
IPY GOOD-HOPE project which covers the northern part of the Atlantic sector 
of the Southern Ocean. The part of the cruise in Drake Passage is part of 
the French programme DRAKE. The global impact of the regional Processes will 
be considered in the BIAC (Bipolar Atlantic Thermohaline Circulation) IPY 
project. The cruise occurs in the context of the MARCOPOLI programme of the 
Hermann von Helmholtz Association of German Research Centres (HGF). It is a 
contribution to the Climate Variability and Predictability (CLIVAR) and the 
Climate and Cryosphere (CIiC) projects of the World Climate Research Programme 
(WCRP). The ULSs are a contribution to the Antarctic Sea Ice Thickness Project 
(AnSITP). The deployment of floats occured in the framework of the international 
Argo programme which contributes to the Global Ocean Observing System (GOOS).

As a contribution to the International Polar Year 2007/2008 the cruise 
was part of the CASO - (Climate of Antarctica and the Southern Ocean) 
and the GEOTRACES projects. It was the aim to measure ocean currents, 
temperature, salinity and concentrations of many trace substances in 
the Southern Ocean. The descending motions in the Southern Ocean are 
part of the world wide oceanic overturning circulation. They affect the 
role of the ocean in climate change and biogeochemical cycles. Our 
measurements raise the question as to whether the deep reaching, 
descending motion of the overturning, increases again after a phase of 
slackening. For more than a decade we have observed that the 
temperatures in the deep Weddell Sea were rising which suggested the 
reduction of the deep reaching water mass formation in the Antarctic 
Ocean. Now the temperature is decreasing again. This occurs at a time 
when sea ice extent in summer is increasing and shows clearly that the 
potential influence of global warming is not simply to identify from 
the background of decadal variations.

It is of special interest, that the evaluation of satellite data by 
NSIDC indicated clearly that the Antarctic summer 2007/2008 was the one 
with the largest ice extent on record. This trend which is particularly 
strong in the Atlantic sector of the Southern Ocean is in clear 
contrast to the Arctic where a strong decrease of the summer ice extend 
is observed. To understand the opposing trends in the Antarctic and the 
Arctic is an obvious aim of our cruise. Because those changes occur 
over decades and are subject to significant spatial variations ships 
cruises like the one of Polarstern are not enough to track them with 
sufficient accuracy. Therefore we need comprehensive autonomous 
observing systems which can be moored or feely drifting. They are a 
component of the Southern Ocean Observing System (SOOS) which is under 
development these days. As a contribution to such a system we deployed, 
in international cooperation, 18 moored systems and recovered 20 of 
them. With the recording period of three years we have reached a record 
length. We deployed 67 floats, the ones which were deployed in the Weddell Sea 
are able to operate under the ice. They have an operation period of up to five 
years and form a network of unprecedented coverage of this part of the 
earth.

During the International Polar Year 2007/2008 we expected not only to 
provide new knowledge on the role of the polar areas in the earth 
system, but in addition, it was an aim of high priority to include the 
public and, in particular, the younger generation in actual research 
and instruct them comprehensively. For this purpose, we had two 
teachers on board. They participated actively in the research work and 
transmitted their experiences on a regular basis to their students, 
colleagues and newspapers by telephone, email and internet. Their 
experiences will reach other schools via an IPY teacher's network and 
hopefully school books too.



2.  CASO - (CLIMATE OF ANTARCTICA AND THE SOUTHERN OCEAN)

The CASO project (Climate of Antarctica and the Southern Ocean) takes 
up work which had started in the WECCON project (Weddell Sea Convection 
CONtrol). It aims to investigate processes which occur in the Atlantic 
Sector of the Southern Ocean and Drake Passage in cooperation with the 
Bjerknes Centre for Climate Research in Bergen, Norway and the British 
Antarctic Survey (BAS). In the framework of iAnZone, a programme 
associated to SCOR (Scientific Committee of Oceanographic Research) and 
its IPY SASS I project (Synoptic Antarctic Shelf Slope Interactions 
Study) observation occur in the area of Maud Rise and the Antarctic 
Coastal Current. The observations occur jointly with the IPY GOOD-HOPE 
project which covers the northern part of the Atlantic sector of the 
Southern Ocean. The global impact of the regional Processes will be 
considered in the BIAC (Bipolar Atlantic Thermohaline Circulation) IPY 
project. The cruise occurs in the context of the MARCOPOLI programme of 
the Hermann von Helmholtz Association of German Research Centres (HGF). 
It is a contribution to the Climate Variability and Predictability (CLI 
VAR) and the Climate and Cryosphere (CIiC) projects of the World 
Climate Research Programme (WCRP). The ULS are a contribution to the 
Antarctic Sea Ice Thickness Project (AnSITP). The deployment of floats 
occurs in the framework of the international Argo programme which 
contributes to the Global Ocean Observing System (GOOS).


2.1  DECADAL VARIATIONS OF WATER MASS PROPERTIES IN THE ATLANTIC SECTOR

     Olaf Boebel(1), Carmen Boening(1), Luisa    (1)Alfred -Wegener-Institut
     Christini(1), Eberhard Fahrbach(1),         (2)CNRS-LEGOS
     Veronique Garcon(1), Olaf Klatt(1),         (3)OPTIMARE
     Marielle Lacombe (2), Matthias              (4)LOCEAN
     Monsees(3), Ismael Nunez-Riboni(1), 
     Christine Provost(4), Alice 
     Renault(4), Gerd Rohardt(1), Hendrik 
     Sander (3), Nathalie Sennechael(4), 
     CTD watch since Jubany, Aurelie Spadone(4), 
     Olaf Strothmann(1), Joel Sudre(2), 
     Stephan Theisen(1)

Objectives

The densest bottom waters of the global oceans originate in the 
Southern Ocean. Production and export of these dense waters constitute 
a vital component of the global climate system. The formation of dense 
water in polar areas is controlled to a large extend by the delicate 
balance between supply of fresh water through precipitation and melt of 
continental and sea ice and the extraction of freshwater by sea ice 
formation and evaporation. Therefore the Southern Ocean's part of the 
global freshwater cycle links continental and oceanic conditions. It consists 
in the transport of freshwater from the continent through melting of 
ice shelf and icebergs and is strongly mediated by redistribution of 
freshwater through the highly variable and moving sea ice cover on 
which snow is accumulated as well as by the oceanic circulation. 
Coupled models predict an intensification of the freshwater cycle in 
the context of global warming. Observations of the freshening of 
Subantarctic Mode, intermediate and deep waters suggest that the 
intensification is ongoing. Therefore the better understanding of the 
Southern Ocean freshwater balance is urgently needed. It can only be 
achieved by a quasi-simultaneous comprehensive circumpolar assessment 
by multi-platform observations and modelling.

The influence of Southern Ocean waters can be traced far into the 
northern hemisphere. As deep and bottom waters, they represent the 
deepest layer of the global overturning circulation. The conditions in 
the Southern Ocean are largely controlled by the Antarctic Circumpolar 
Current (ACC), the worlds most powerful current system, which 
transports about 140 Sv (106 m3 1) of water at all depths. It connects 
the three ocean basins and forms an isolating water ring around the 
Antarctic continent. South of the ACC, in the subpolar region, warm and 
salty water masses are carried in the subpolar gyres to the continental 
margins of Antarctica. The most prominent are the Weddell and Ross 
gyres. In the subpolar gyres, water mass modifications occur through 
ocean-ice-atmosphere interactions and mixing with adjacent water 
masses. The ACC is dynamically linked to meridional circulation cells, 
formed by southward ascending flow in intermediate depth feeding into 
northward flow above and below. In the deep cell water sinking near the 
continental water spreads to the adjacent ocean basins, in the shallow 
cell the northward flow occurs in the near surface layers. Dense waters 
are produced at several sites near the continental margins of 
Antarctica. Quantitatively the most important region for dense water 
formation may well be the Weddell Sea, however other areas provide 
significant contributions as well.

The basic mechanism of dense water generation involves upwelling of 
Circumpolar Deep Water which is relatively warm and salty into the 
surface layer where it comes into contact with the atmosphere and sea 
ice. The newly formed bottom water is significantly colder and slightly 
fresher than the initial Circumpolar Deep Water which indicates heat 
loss and the addition of freshwater. Since freshwater input in the 
upper oceanic layers is prohibitive to sinking through increasing 
stability of the water column, it has to be compensated by salt gain 
through fresh water extraction. The upwelled water is freshened by 
precipitation and melting of glacial and sea ice. Freshwater of glacial 
origin is supplied from the ice shelves or melting icebergs. Ice 
shelves melt at their fronts and undersides related to the oceanic 
circulation in the cavity. Iceberg melting depends highly on the 
iceberg drift and can supply freshwater to areas distant from the 
shelves as the Antarctic frontal system. Due to the spatial separation 
of major freezing and melting areas of sea ice cooling and salt release 
during sea-ice formation cause the compensation of the freshwater gain 
and subsequently the density increase which is needed for bottom water 
formation. Significant parts of the salt accumulation occur on the 
Antarctic shelves in coastal polynyas. Since extreme heat losses can 
only occur in ice free water areas, the polynyas are areas of intense sea 
ice formation. Offshore winds compress the newly formed sea ice and keep 
an open sea surface in the polynyas.

The cold and saline water accumulated on the shelves can descend the 
continental slope and mix with water masses near the shelf edge or it 
circulates under the vast ice shelves, where it is further cooled below 
the surface freezing point and freshened by melting of the ice shelf. 
The resulting Ice Shelf Water spills over the continental slope and 
mixes with ambient waters to form deep and bottom water. For both 
mechanisms relatively small scale processes at the shelf front, 
topographic features and the nonlinearity of the equation of state of 
sea water at low temperatures is of special importance to induce and 
maintain the sinking motion. The different processes, topographic 
settings and atmospheric forcing conditions lead to variable spatial 
characteristics of the resulting deep and bottom water masses which 
than spread along a variety of pathways to feed into the global oceanic 
circulation. Climate models suggest that dense water formation is 
sensitive to climate change. However, since the relatively small scale 
formation processes are poorly represented in the models further 
improvement is needed. The overturning affects as well the 
biogeochemical cycles and consequently its change can have a 
significant impact on ocean carbon uptake.

The properties and volume of the newly formed bottom water underlies 
significant variability on a wide range of time scales, which are only 
poorly explored due to the large efforts needed to obtain measurements 
in ice covered ocean areas. As for the atmospheric driving forces, the 
sea ice and upper ocean layers, seasonal variations are partly known 
and normally exceed in intensity the other scales of variability. 
However the spatial distribution pattern of the variability is only 
poorly resolved e.g. seasonal cycles of sea ice thickness are only 
available at a few sites. An estimate of the sea ice mass as a baseline 
to detect change is still not possible due to the missing measurements 
of sea ice thickness. Longer term variations of the atmosphere-ice-
ocean system as the Antarctic Circumpolar Wave, the Southern 
Hemispheric Annular Mode and the Antarctic Dipole are only poorly 
observed and understood. Their influence on or interaction with oceanic 
conditions are only guessed on the basis of models which are only 
superficially validated due to lack of appropriate measurements.

The extreme regional and temporal variability represents a large source 
of uncertainty when data sets of different origin are combined. 
Therefore circumpolar data sets are needed of sufficient spatial and 
temporal coverage. At present such data sets can only be acquired 
satellite remote sensing. However, to penetrate into the ocean interior 
and to validate the remotely sensed data, an ocean observing system is 
needed, which combines remotely sensed data of sea ice and surface 
properties with in-situ measurements of atmospheric, sea ice and 
oceanic properties.

To achieve further progress significant steps occurred in the 
development of appropriate technology and logistics. Oceanic properties 
are measured under the sea ice which required the development of under-
ice acoustic ranging and data transmitting systems. To construct from 
the achievable observations a comprehensive circumpolar view, model 
assimilations have to be done which require the development of appropriate 
models.

During the International Polar Year 2007/2008 a set of meridional 
transects was occupied in one season to provide the first synoptic 
snapshot of the circulation, stratification and biogeochemical status 
of the Southern Ocean. It included each of the "chokepoint" sections 
between Antarctic and the southern hemisphere continents. ANT-XXIV/3 
covered the African chokepoint in the Atlantic Sector of the Southern 
Ocean, the Weddell Sea and Drake Passage. The northern part of the 
section south of Africa was taken care by BONUS-GOODHOPE.

Work at sea

The Polarstern cruise ANT-XXIV/3 complemented the efforts during the 
International Polar Year 2007/2008 to obtain in-situ observations in 
the Atlantic sector of the Southern Ocean in order to allow a 
circumpolar view. Time series stations with moored instruments provided 
measurements in the deep and the surface layers and of ice thickness. 
For this purpose moorings with current meters, temperature and salinity 
sensors as well as upward looking sonars were recovered and redeployed. 
The cruise concentrated to three major areas: the Greenwich meridian, 
the Weddell Sea and Drake Passage.

Measurements occurred along the Greenwich meridian, across the Weddell 
Sea and Drake Passage (Fig. 21). The ship borne surveys in summer are 
imbedded in the time series measurements with moorings, drifters and 
floats to derive the effect of the seasonal variability on transfer 
processes and to avoid the aliasing effect on longer term observations. 
Moorings were recovered (Fig. 2.lb) and redeployed (Fig. 2.lc). The 
details of the moored instruments are summarized in Tab. 25 to 2.6. The 
spreading of floats is able to extend the data from the sections over 
larger parts of the area. Ship borne meridional transects were obtained 
to determine water mass properties including tracer concentrations 
(Fig. 2.1.d).


Fig. 2.1:  The cruise track of ANT-XXIV/3 (a) and the locations of 
           moorings recovered (b) deployed (c) and the CTD stations (d)


Profiling floats were deployed. The float system has to complement Argo 
in ice-fee and under-ice condition to reach a global coverage. Moorings 
with sound sources for under ice navigation were recovered and 
redeployed. The IPY set the goal of achieving at least the 3° X 3° 
sampling of the global array throughout the southern hemisphere oceans 
south of 30°S, for the full duration of the IPY (March 2007 to March 
2009). Acoustically tracked floats will provide profiles and current 
velocities from key ice-covered seas. The floats are programmed to 
continue to profile and store data beneath ice. Once the floats detect 
open water, the stored profiles are transmitted. While the position of 
the sub-ice profiles is not known without acoustic navigation, the 
floats can survive the winter and the stored profiles provide a 
statistical description of winter stratification.

Preliminary results

Despite the fact that the data requires comprehensive processing and 
calibration work, the quality of our instruments is so high, that a 
first look on the preliminary data from the hydrographic survey 
indicated that the cooling of the Warm Deep Water which was observed 
since the mid 90ties has come to a halt. Together with the observation 
of an earlier warming until the mid 90ties this suggests that decadal 
fluctuations dominate the variability. Now we can compare the 
atmospheric forcing during the last years with the one in the early 
nineties to better understand the forcing mechanism of the 
fluctuations. The temperature and the salinity of the Weddell Sea 
Bottom Water increased further during the last three years at the 
Greenwich meridian. This observation provides evidence of the evolution 
that we have followed since the mid 90s and raised the question even 
clearer: did global warming reach the deep sea or is it only a 
fluctuation on a timescale of decades. Because our Australian 
colleagues report that the salinity of the bottom water in the Ross Sea 
and off Adelie Land keeps on decreasing, this regional contrast 
requires an explanation to which we obtained a hint from the data which 
were obtained in the western Weddell Sea where the data from the moored 
instruments showed cooling of the Weddell Sea Bottom Water.

The descending motions in the Southern Ocean are part of the world wide 
oceanic overturning circulation. They affect the role of the ocean in 
climate change and biogeochemical cycles. Our measurements raise the 
question as to whether the deep reaching, descending motion of the 
overturning, increases again after a phase of slackening. For more than 
a decade we have observed that the temperatures in the deep Weddell Sea 
were rising which suggested the reduction of the deep reaching water 
mass formation in the Antarctic Ocean. Now the temperature near the 
formation area in the western Weddell Sea is decreasing again. This 
occurs at a time when sea ice extent in summer is increasing and shows 
clearly that the potential influence of global warming is not simply to 
identify from the background of decadal variations.


2.1.1 CTD transects

Hydrographic surveys were carried out along the Greenwich meridian, 
from Kapp Norvegia to the northern end of the Antarctic Peninsula and 
across Drake Passage with a CTD (Conductivity/Temperature/Depth) probe 
and a rosette water sampler (Fig. 2.ld). Samples were taken to measure 
the components of the CO2 system, oxygen, nutrients, and tracers.

A total number of 217 CTD stations were carried out during the cruise. 
Two independent systems were used. The standard CTD/water sampler (here 
indicated as "AWI CTD") consists of a SBE91 1 plus CTD system in 
combination with a carousel water sampler SBE32 with 24 12-l bottles. 
Bottle number 1 and 2 were not used because of up- and down looking 
ADCPs which have been installed at the carousel frame. To determine the 
distance to the bottom we used an altimeter from Benthos.

In addition to this a transmissiometer from Wetlabs, a SBE43 oxygen 
sensor from Seabird Electronics and a Dr. Haardt Fluorometer has been 
used.

The second system was the ultraclean water sampler (here indicated as 
"NIOZ CTD") from the GEOTRACES group (See 3.1.9). This water sampler 
was also equipped with a SBE91 1 plus CTD. In addition the following 
external sensors were installed at the NIOZ CTD: I) a SBE43 oxygen 
sensor from Seabird, II) a Seapoint OBS, and Ill) a Chelsea Aquatracka 
fluorometer. A high precision thermometer SBE35 was used to check the 
CTD temperature sensors. A mechanical bottom switch with 10 m rope 
length was used. The altimeter did not work reliably.

Both CTD systems were equipped with two independent CT sensor pairs. Each 
senor pair has its own pump to flush the cell at a constant flow of water. 
The oxygen sensor was integrated in the first pair. The serial numbers, 
the type of each sensor and the calibration dates of each device can be 
taken from Tab. 21 and 2.2.


Tab. 2.1a:  Configuration of the AWI CTD

CTD SBE9llpIus SN 0287 with rosette SBE 32
Pressure (Type/SN, Cal.-date)      Digiquartz 4 19K-105/SN 51197, 20.11.1992

Sensors in pair:
                                   Pair 1                  Pair 2
---------------------------------  ----------------------  ----------------------
Temperature (Type/SN, Cal.-Date)   SBE 03P/2929, 10.04.07  SBE 03P/1373, 10.05.07
Conductivity (Type/SN, Cal.-Date)  SBE 04C/3173, 26.04.07  SBE 04C/2470, 10.04.07


Tab. 2.2a:  Additional sensors of the AWI CTD

Sensor            Type                           Cal.-date  Analog channel 
                                                              (Voltage)
----------------  -----------------------------  ---------  -------------
Altimeter         Benthos PSA 916D SN 208            -            6
Transmissiometer  WET labs C-Star SN CST-814DR    23.07.99        0
Fluorometer       Dr Haardt Mod. 1101.3 SN 8060      -            2
Oxygen (Type/SN)  SBE43 SN 0743                   28.02.06        4


Tab. 2.1b:  Configuration of the NIOZ CTD

CTD SBE91 1 plus SN 0230 with Ultraclean Water Sampler
Pressure (Type/SN, Cal.-date)      Digiquartz 419K-105/SN 43517, 28.02.2006

Sensors in pair.
                                   Pair 1                  Pair 2
---------------------------------  ----------------------  ----------------------
Temperature (Type/SN, Cal-Date)    SBE 03P/2118, 09.11.07  SBE 03P/1360, 28.11.07
Conductivity (Type/SN, Cal-Date)   SBE 04C/3035, 09.11.07* SBE 04C/3385, 09.01.08
                                   SBE 04C/0776, 29.11.07**

 *: used from station  97 cast 2 until station 135 cast 1 
**: used from station 138 cast 1 until station 252 cast 1


Tab 2.2b:  Additional sensors of the NIOZ CTD

Sensor            Type                           Cal.-date  Analog channel 
                                                              (Voltage)
----------------  -----------------------------  ---------  -------------
Altimeter         unknown                            -            -
Transmissiometer  Seapoint OBS SN 1066               -            -
Fluorometer       Chelsea Aquatracka MKIII SN 092    -            -
Oxygen (Type/SN)  SBE43 SN 0654                   22.11.07        -


The salinity is given in Practical Salinity Units (PSU). Salinity samples were 
analysed with an Autosal salinometer 8400B from Guildline Instruments to check 
and probably correct the conductivity measurements of the CTD. Therefore once 
per day double samples were taken from 6 depth levels which show no significant 
gradient in the salinity differences. The salinity measurements were directly 
compared with the CTD measurements. The water samples were measured in reference 
to Standard water batch no P149 (K1 5=0.99984) from 10. May 2007.

AWI CTD

The difference between conductivity from sensor pair 1 and 2 showed an 
increasing drift of the primary conductivity sensor from the first to the last 
profile. This was confirmed by the post-calibration of the sensors carried out 
after the cruise. Therefore the secondary sensor pair was taken for the final 
data set. 21 deep casts were made with both, the AWI- and the NIOZ CTD. These 
profiles were used to compare all temperature sensors against each other 
resulting in a temperature correction of -0.00065°C for the secondary 
temperature sensor.

The pre- and post-calibration of the secondary conductivity sensor shows no 
drift but the evaluation of the Autosal measurements indicated a pressure 
dependent correction, which is in the order less than the sensor specification 
(see Fig. 2.2).


Fig. 2.2: Salinity differences of AWI CTD plotted versus pressure.


The uncorrected salinity is in the range of the sensor specification, see Fig. 
2.3 below. The applied correction based on the Autosal measurements and the pre- 
and post-calibration from the manufacturer. Scorr = SCTD + AS with AS = a + b * 
P P:= Pressure (dbar) a := 3.8 * iO b:= -8.6667 * 1O'


Fig. 2.3: Salinity differences of AWI CTD before and after correction from
          Autosal measurements taken from deep samples (greater 2,000 m) only.
          The shaded region indicates the range of the sensor specification.


NIOZ CTD

The secondary sensor pair was influenced by a strong noisy signal. The reason is 
still unclear. The same feature was already observed during the Polarstern 
cruise ARK-XXII/3. Therefore the primary sensor pair was taken for the final 
data set in spite of a sensor exchange due to a broken conductivity cell which 
happened at station 135, cast 1. No correction must be applied for the secondary 
temperature, which results from comparison between the secondary and primary 
sensors. This result was confirmed by the pre- and post-calibration and the 
comparison between AWIand NIOZ CTD (see 21 deep casts).

No correction must be applied for the conductivity carried out with SN 3035; see 
Fig. 24. Data measured with the spare sensor SN 0776 need to be corrected with a 
constant offset of -O001 37.These correction could be confirmed with the help of 
the pre- and post-calibration results.


Fig. 2.4: Salinity differences of NIOZ CTD before and after correction from
          Autosal measurements taken from deep samples (greater 2,000 m) only.
          The shaded region indicates the range of the sensor specification.


After each single correction step temperature and salinity were checked using 
the T/S relation including all available profiles from AWI and NIOZ CTD and in 
addition data from previous cruises were taken into account. This method was 
used to correct the different performance of the two systems which was finally 
controlled by contour plots (Fig. 25).


Fig. 2.5: Example of the density contour plot from the layer 2,000 to 2,500 m    
          along the Greenwich meridian, which demonstrates the influence by the 
          use of two independent CTD systems before and after the final 
          processing. A) is the uncorrected and B) the corrected density contour 
          plot. The arrows in the upper panel showed the location of the 
          neighbouring CTD casts carried out with the AWI and NIOZ CTD.


The data quality for salinity is better than ± 0.002 and for temperature better 
than :t 0.001 K.

The temperature and salinity data are presented as vertical sections in Fig. 2.6 
to 28.


Fig. 2.6: Vertical transect of potential temperature (top panel) and salinity 
          (bottom panel) along the Greenwich meridian

Fig. 2.7: Vertical transect of potential temperature (top panel) and salinity 
          (bottom panel) across the Weddell Sea from Kapp Norvegia (right) to 
          Joinville Island (left)

Fig. 2.8: Vertical transect of potential temperature (top panel) and salinity 
          (bottom panel) across the Drake Passage from South America (left) to 
          the Antarctic continent (right)



2.1.2  Underway measurements

Underway measurements with a vessel mounted 150 kHz-Ocean Surveyor ADCP from RD 
Instruments and two SBE21 thermosalinographs from Seabird Electronics were 
conducted along the whole track to supply temperature, salinity and current data 
at a high spatial resolution (Figs. 29, 210, and 2.11). The intakes of the 
thermosalinographs are mounted in 5 m depth in the bow thruster tunnel (TSB) and 
in 11 m depth in the keel (TSK). Both instruments were controlled by taking 
water samples each day which were measured on board with the Autosal 8400B.

The final corrected and verified thermosalinograph data can be retrieved from 
the AWI database using:

http://www.awi.de/de/infrastruktur/schiffe/polarstern/bordwetterwarte/continuous_measurements/


Fig. 2.9: Near surface temperature and salinity from the thermosalinograph
          (keel) along the trackline from South Africa (left) to the Antarctic 
          continent (right)

Fig. 2.10: Near surface temperature and salinity from the thermosalinograph 
           (keel) across the Weddell Sea from Joinville Island (right) to Kapp
           Norvegia (left)

Fig. 2.11: Near surface temperature and salinity from the thermosalinograph
           (keel) across Drake Passage from South America (left) to the 
           Antarctic continent (right)



2.1.3 LADCP (Lowered acoustic Doppler profiler) 

Objectives

Full depth profiles of horizontal ocean currents were measured with two lowered 
acoustic Doppler profilers (LADCP) attached to the AWI OlD Rosette. CTD/LADCP 
stations were performed along the three transects (the Greenwich meridian, the 
Weddell Sea and the Drake Passage, Fig. 21), in order to complement the mooring
arrays. The LADCP data along these transects in the Atlantic sector of the 
Southern Ocean will contribute to a better understanding of the Southern Ocean 
in the Atlantic sector including the Weddell Sea. The Antarctic Circumpolar 
Current (ACC), is a key element of the global climate system. The LADCPs data 
will provide a picture of the ACC transport across Drake Passage within a period 
of approximately 12 days. With a high resolution CTD/LADCP station section, the 
LADCP data will help to document the current structure.

Work at sea

The measurements were done with two RDI Workhorse 300 kHz ADCP5. An external 
battery case was used to supply power to the two LADCPs. Between two consecutive 
stations, the data from the two LADCP5 were downloaded from their internal 
memory card and the power supply was checked. A Master/Slave configuration was 
used in which the Master ADCP was downward looking and the Slave ADCP was upward 
looking. Unfortunately the signal could not be synchronised between the two 
LADCPs and a unique configuration was used for each LADCP. The LADCP 
measurements are summarized in Tab. 2.3 and 2.4.

On the Greenwich meridian section we did a total of 24 profiles with the LADCPs. 
For 13 of them both upward and downward looking LADCP5 worked, and for the 
others only the downward -looking LADCP could get data. On the Weddell Sea 
section we did a total of 52 profiles. On six of them, only the downward-looking 
LADCP was working properly and could acquire data.


Tab. 2.3:  LADCP measurements during ANT-XXIV/3

           Transect                              Greenwich  Weddell   Drake 
                                                 meridian     Sea    Passage
           ------------------------------------  ---------  -------  -------
           Number of CTD/LADCP stations             24        52        31
           Downward looking profile alone           11         6        12
           Upward and downward looking profiles     13        46        31


Expected results

Processing was not completed on board. The quality of the data has to be tested 
in order to validate the raw data. The second step consists in the computation 
of the currents over the whole water column. The data coming from vessel mounted 
ADCP (VADCP) will be used to better constraint the first 300 meters. The 
profiles through the whole Drake Passage will allow the computation of the ACC 
transport across the section.


Tab. 2.4: Location of the LADCP profiles

Station     Date      Lat          Lon        Depth   LADCP
                                               [m]    Down  Up
----------  --------  ----------  ----------  ------  ----  --
PS711099-2  13.02.08  41° 8.71'S   9°58.28'E  4761.0    1    1
PS71I101-3  13.02.08  42°21.36'S   8°59.93'E  4640.0    1    1
PS71/102-2  15.02.08  44°39.56'S   7° 5.77'E  4606.0    1    0
PS71/104-6  17.02.08  47°39.05'S   4°16.20'E  4544.2    1    0
PS71/106-1  18.02.08  48°54.71'S   2°47.88'E  4094.3    1    0
PS71/108-2  19.02.08  51°29.95'S   0° 0.02'W  2775.4    1    0
PS71/112-1  20.02.08  52°30.20'S   1°22.26'W  2811.4    1    0
PS71/113-3  20.02.08  52°59.75'S   0° 2.30'E  2522.4    1    0
PS71/115-2  21.02.08  53°30.95'S   0° 0.30'E  2657.7    1    0
PS71/118-2  21.02.08  54°30.19'S   0° 1.76'E  1718.8    1    0
P571/121-1  22.02.08  55°29.76'S   0° 0.34'W  3837.3    1    0
P571/124-1  22.02.08  56°30.34'S   0° 1.22'E  4055.3    1    1
P571/125-1  23.02.08  57° 0.11'S   0° 0.17'W  3837.3    1    1
PS71/127-1  23.02.08  57°29.91'S   0° 1.20'E  4056.7    1    1
P571/130-1  24.02.08  58°29.96'S   0° 0.03'W  4184.8    1    0
P571/131-1  24.02.08  59° 0.06'S   0° 0.17'E  4584.2    1    1
P571/134-1  25.02.08  59°30.98'S   0° 1.77'E  4710.8    1    1
P571/137-1  26.02.08  60°29.99'S   0° 0.04'E  5355.5    1    1
P571/140-1  27.02.08  61°29.91'S   0° 0.35'W  5378.0    1    1
PS71/141-2  27.02.08  61°59.98'S   0° 0.04'E  5359.2    1    1
P571/143-1  27.02.08  62°30.58'S   0° 0.56'W  5337.7    1    1
P571/146-1  28.02.08  63°30.01'S   0° 0.03'W  5236.3    1    0
P571/149-1  29.02.08  64°29.99'S   0° 0.04'E  4660.9    1    1
P571/152-1  29.02.08  65°30.04'S   0° 0.34'E  3972.6    1    1
PS71/157-5  08.03.08  66°28.60'S   0° 1.85'W  4493.2    1    0
P571/158-1  08.03.08  66°14.73'S   0° 1.07'W  3683.5    1    1
PS71/159-4  08.03.08  66° 1.41'S   0° 7.93'E  3547.5    1    0
PS71/161-4  09.03.08  66°29.93'S   0° 0.20'E  4536.5    1    0
P571/165-1  10.03.08  67°30.01'S   0° 0.08'E  4625.5    1    0
P571/169-1  10.03.08  68°30.02'S   0° 0.12'E  4256.2    1    1
P571/171-1  10.03.08  68°45.02'S   0° 0.00'W  3627.7    1    0
P571/173-1  10.03.08  69°11.89'S   0° 1.61'E  2905.2    1    0
P571/174-1  11.03.08  69° 5.96'S   0° 0.24'W  3223.5    1    0
P571/175-1  11.03.08  69° 0.72'S   0° 0.05'E  3374.5    1    0
P571/177-1  11.03.08  69°18.08'S   0° 0.31'W  2457.2    1    1
P571/178-1  11.03.08  69°24.07'S   0° 0.18'W  2000.5    1    1
P571/179-1  12.03.08  69°30.98'S   0° 3.14'W  1519.2    1    1
P571/181-1  12.03.08  69°36.58'S   0° 0.34'W  1506.2    1    1
P571/183-1  12.03.08  69°36.55'S   0°40.05'W  2264.5    1    1

Station     Date      Lat          Lon        Depth   LADCP
                                               [m]    Down  Up
----------  --------  ----------  ----------  ------  ----  --
PS71/184-1  13.03.08  69° 0.00'S   6°58.33'W  2942.5    1    1
PS71/185-1  15.03.08  69°21.69'S  16°25.87'W  4737.5    1    1
PS71/186-1  15.03.08  69° 3.86'S  17°21.38'W  4766.5    1    1
PS71/188-1  16.03.08  68°23.60'S  19° 4.19'W  4826.7    1    1
PS71/189-1  16.03.08  67°56.57'S  20° 0.04'W  4905.0    1    1
PS71/190-1  17.03.08  67°35.95'S  21°47.96'W  4905.2    1    1
PS71/192-1  17.03.08  66°56.84'S  25°17.27'W  4852.0    1    1
PS71/193-1  18.03.08  66°37.26'S  27° 4.85'W  4865.0    1    1
PS711194-1  19.03.08  66°24.72'S  29° 1.09'W  4827.7    1    1
PS71/195-1  20.03.08  66°13.02'S  30°55.42'W  4810.2    1    1
PS71/196-1  20.03.08  66° 0.50'S  32°46.46'W  4789.7    1    1
PS71/197-1  20.03.08  65°48.54'S  34°37.55'W  4787.0    1    1
PS71/198-1  21.03.08  65°36.82'S  36°23.82'W  4771.2    1    1
P571/199-1  21.03.08  65°27.20'S  37°42.46'W  4730.5    1    1
P571/200-1  22.03.08  65°16.95'S  39° 1.32'W  4766.2    1    1
P571/201-1  22.03.08  65° 7.01'S  40°19.31'W  4774.5    1    1
P571/202-1  22.03.08  64°56.89'S  41°39.90'W  4733.2    1    1
P571/205-1  23.03.08  64°33.97'S  44°13.71'W  4592.7    1    1
P571/206-1  24.03.08  64°28.19'S  45°11.21'W  4484.5    1    1
PS71/207-3  24.03.08  64°23.03'S  45°55.50'W  4442.5    1    1
P571/208-1  24.03.08  64°17.84'S  46°38.62'W  4392.2    1    1
P571/209-1  25.03.08  64°11.42'S  47°31.81'W  4200.2    1    1
P571/211-1  26.03.08  63°54.58'S  48°39.48'W  3725.0    1    1
P571/212-1  26.03.08  63°54.37'S  49° 4.69'W  3520.2    1    1
P571/213-1  26.03.08  63°53.45'S  49°35.38'W  3304.2    1    1
P571/214-1  27.03.08  63°51.31'S  50° 0.28'W  2938.0    1    1
P571/215-1  27.03.08  63°46.68'S  50°25.67'W  2660.2    1    1
P571/216-5  28.03.08  63°41.47'S  50°50.39'W  2536.7    1    1
P571/217-1  28.03.08  63°42.09'S  51°18.52'W  2255.5    1    1
P571/218-1  28.03.08  63°36.85'S  51°40.05'W  1786.5    1    1
P571/219-1  28.03.08  63°32.70'S  51°53.33'W  1230.0    1    1
PS71/220-2  28.03.08  63°28.17'S  52° 6.35'W   939.5    1    0
P571/221-1  28.03.08  63°24.11'S  52°32.23'W   514.5    1    0
P571/222-1  29.03.08  63°21.19'S  52°51.24'W   444.5    1    1
PS71/223-1  29.03.08  63°17.20'S  53°13.97'W   431.0    1    1
P571/224-1  31.03.08  62°12.28'S  58°56.04'W    90.5    1    1
P571/225-1  01.04.08  60°42.41'S  53°36.97'W  1496.2    1    0
PS71/226-3  02.04.08  60°37.63'S  53°49.88'W  2777.2    1    1
P571/227-1  02.04.08  60°32.15'S  54° 5.65'W  2971.0    1    1
P571/228-1  02.04.08  60°26.44'S  54°19.42'W  3185.0    1    1
P571/229-1  02.04.08  60°16.28'S  54°47.76'W  3265.2    1    1

Station     Date      Lat          Lon        Depth   LADCP
                                               [m]    Down  Up
----------  --------  ----------  ----------  ------  ----  --
PS71/231-2  03.04.08  59°55.50's  55°44.52'W  3577.5    1    1
PS71/232-1  03.04.08  59°45.59'S  56°14.98'W  3629.2    1    1
PS71/233-2  04.04.08  59°33.51'S  56°40.24'W  3578.2    1    0
PS71/234-1  05.04.08  59°21.48'S  57° 8.42'W  3556.5    1    1
PS71/235-1  05.04.08  59° 9.49'S  57°37.99'W  3651.2    1    1
PS711236-6  06.04.08  58°59.99'S  58° 8.69'W  3790.2    1    0
PS711237-1  06.04.08  58°39.12'S  58°47.30'W  3928.5    1    0
PS711238-3  06.04.08  58°17.02'S  59°28.18'W  3543.0    1    0
PS711239-1  07.04.08  58° 5.85'S  60' 0.16'W  4082.7    1    1
PS71/240-1  07.04.08  57°52.39'S  60°27.14'W  3898.2    1    1
PS71/241-1  07.04.08  57°38.36'S  60°53.81'W  3500.7    1    0
PS71/242-1  08.04.08  57°30.13'S  61° 6.39'W  3911.2    1    0
PS71/243-1  08.04.08  57°23.94'S  61°24.32'W  3731.0    1    0
PS71/244-6  09.04.08  56°51.50'S  62°30.20'W  4146.2    1    1
PS71/246-1  10.04.08  57° 6.96'S  61°58.54'W  3774.0    1    1
PS71/247-1  10.04.08  56°39.70'S  62°48.94'W  4065.0    1    1
PS71/248-1  10.04.08  56°25.00'S  63°18.63'W  3982.5    1    1
PS71/250-8  12.04.08  55°43.96'S  64°25.68'W  3822.2    1    1
PS71/251-1  12.04.08  55°20.63'S  65° 9.19'W  1762.7    1    1
PS71/252-2  12.04.08  55° 7.49'S  65°29.44'W   468.2    1    1
PS71/253-1  12.04.08  55°13.66'S  65°20.74'W  1061.2    1    1
PS71/254-1  13.04.08  55°27.98'S  64°56.91'W  2563.2    1    0
P571/255-1  13.04.08  55°35.35'S  64°44.01'W  3619.0    1    0
P571/256-1  13.04.08  55°53.30'S  64°15.31'W  3878.0    1    0
P571/258-1  13.04.08  56° 0.24'S  64° 0.56'W  3987.7    1    0
                                              TOTAL   106   73
                                              ZERO     39   20
                                              Weddell  36   34
                                              DRAKE    31   19
                                                      106   73



2.1.4  Moorings

Work at sea

In order to detect variations with sufficient time resolution to avoid the 
effect of aliasing and to be able to separate processes of a wide range of time 
scales quasicontinuous measurements from moored instruments are needed.

Recovery and deployment of moorings

Since the previous cruise ANT-XXII/3 moorings were maintained along two 
sections. The first are a set of 9 moorings on the Greenwich meridian. The other 
section crosses the Weddell Sea from Kapp Norvegia towards Joinville Island at 
the tip of the Antarctic Peninsula.

Greenwich meridian moorings

The moored observing system on the Greenwich meridian is maintained since 1996. 
Current meter moorings were exchanged in 1998, 1999, 2001, 2003 and 2005. But 
three moorings AW1229, AW1231 and AW1232 were already exchanged 2006 because of 
the high sample rate of the ADCP5 in these moorings. Some mooring positions were 
modified and additional ones were added during this period. During the present 
leg the moorings deployed in 2005 (Figs. 21b, 212 and Tab. 2.5) were recovered 
and a new reduced set was deployed (Figs. 2.1 c, 2.14 and Tab. 2.6).

The two southernmost moorings covered the area of the coastal and slope current. 
West of Maud Rise there are three moorings equipped with temperature-
conductivity recorders from approximately 250 to 750 meters depth to monitor the 
stratification in the transition from the Winter Water to the Warm Deep Water. 
These data should indicate the potential pre-conditioning for the occurrence of 
a polynya. Three of the northernmost moorings were not redeployed and the 
remaining northern mooring was continued with a near bottom CT recorder only. 
The southernmost mooring was not redeployed neither. The observations along the 
Greenwich meridian are concentrated on Maud Rise and the continuation of the sea 
ice thickness measurements with the Upward Looking Sonars (ULS) in combination 
with the ADCP.

Two sound sources were exchanged in moorings AW1229 and AW1231 to locate floats. 
Further details are given in 2.1.5.

Weddell Sea moorings

The first mooring section across the Weddell Sea began 1989 and was continued 
until 1995 and 1997 with one single mooring respectively. 2005 three of the 
longest continued mooring sites were deployed again in 2005 (Figs. 2.1 b, 2.13 
and Tab. 2.7). The redeployed moorings AW1208 and AW1209 showed increasing 
temperature of the Weddell Sea Bottom Water (WSBW) in the central Weddell Sea. 
For this reason these mooring locations were continued. The instruments were 
focussed on the WSBW layer. Sea ice draft measurements with ULS were also 
continued at AW1208 and AW1207. Due to the weak currents in the centre of the 
Weddell gyre a RDI Longranger ADCP was installed in AW1208 at 300 m depth to 
support the estimates of the sea ice volume transport. All these moorings were 
equipped with sound sources at approximately 800 m depth - further details 
concerning the sound sources see section 2.1.6.

The volume transport of the WSBW which flows northward along the continental 
slope has been previously calculated from moored records. After the break off 
from the Larsen Ice Shelf in 2002 the calculation should be repeated since 
significant changes might have occurred. For this reason additional moorings 
were deployed in the out flowing branch of the Weddell gyre from 900 m depth 
down the continental slope. Locations of these moorings were selected at the 
same sites as previous moorings (Fig. 2.16 and 2.15, Tab. 2.8).


Fig. 2.12: Moorings recovered on the Greenwich meridian
Fig. 2.13: Moorings recovered in the Weddell Sea
Fig. 2.14: Moorings deployed on the Greenwich meridian
Fig. 2.15: Moorings deployed in the Weddell Sea


Tab. 2.5:  Moorings recovered on the Greenwich meridian

Mooring   Latitude    Water  Date         Instrument  Serial  Instr.  Record
          Longitude   Depth  Time         Type        Number  Depth   Length
                      (m)    1. Record                        (m)     (days)
                             last Record
--------  ----------  -----  -----------  ----------  ------  ------  -------
AW1233-7  69°23.60'S  1950   17.02.2005   ULS         46      150     (2)
          00°04.29'W         22:00        AVTP        11890   202     1117(2)
                             12.03.2008   ROM 11      100     699     1117
                             06:00        POD         W402    1700    (1)
                                          SBE37       3810    1903    683
                                          ROM 11      146     1904    1117

AW1232-8  68°59.75'S  3370   19.12.2005   ULS         50      125     (1)
          00°00.16'W         20:00        ADOP                466     (1)
                             11.03.2008   AVTP        10492   745     812
                             04:00        AVT         6856    1804    812
                                          SBE37       211     3312    812
                                          AVT         9179    3313    812

AW1231-7  66°30.67'S  4517   18.12.2005   ULS         41      119     (1)
          00°01.90'W         13:00        SBE37       249     150     810
                             07.03.2008   SBE37       2382    250     716
                             14:00        ADOP        385     309     (1)
                                          SBE37       2383    350     699
                                          SBE37       2235    450     638
                                          SBE37       2385    550     707
                                          SBE37       2384    650     705
                                          AVTP        9212    675     810
                                          SQ          W2-c30  865
                                          AVT         9184    1777    810
                                          SBE37       214     4472    810
                                          AVT         9194    4473    810

AW1230-5  66°00.66'S  3450   08.02.2005   AVTP        9204    194     1123
          00°11.28'E         21:00        SBE37P3     243     200     1123
                             08.03.2008   SBE37       233     300     1123
                             06:00        SBE37       232     400     1123
                                          SBE37       235     500     1123
                                          SBE37       236     600     (2)
                                          SBE37P3     2721    700     1123
                                          AVTP        9214    701     (2)
                                          POD         A401    1560
                                          AVTP        9998    1597    1123
                                          SBE37       238     3403    1123
                                          ROM 11      25      3404    1123

AW1229-7  63°57.17'S  5180   16.12.2005   ULS         49      146     (1)
          00°00.17'W         16:00        SBE37       2611    190     441
                             28.02.2008   SBE37       2386    290     733
                             10:00        ADOP        5848    373     (1)
                                          SBE37       1605    390     679
                                          SBE37       2388    490     729
                                          SBE37       2389    590     702
                                          SBE37       1564    680     600
                                          AVTP        9997    684     803
                                          SQ          W1-c29  832
                                          AVT         9185    1982    803
                                          SBE37       215     5135    803
                                          AVT         9187    5136    803


Mooring   Latitude    Water  Date         Instrument  Serial  Instr.  Record
          Longitude   Depth  Time         Type        Number  Depth   Length
                      (m)    1. Record                        (m)     (days)
                             last Record
--------  ----------  -----  -----------  ----------  ------  ------  -------
AW1227-9  59°04.11'S  4627   04.02.2005   AVTP        10003   231     1115
          00°04.92'E         20:00        AVTPC       10926   723     1115
                             25.02.2008   SBE37PP10   1234    724     1113
                             12:00        AVT         11937   2019    1115
                                          SBE37Pu     1603    4581    1113
                                          AVT         9767    4582    1115

AW1228-7  56°57.56'S  3700   03.02.2005   AVTP        9763    191     1114
          00°01.07'E         16:00        SBE37PuP3   1232    197     1114
                             23.02.2008   SBE37       441     247     1114
                             04:00        SBE37       442     297     1114
                                          SBE37PuP3   1233    347     1114
                                          AVTP        10539   401     1114
                                          SBE37       447     403     1114
                                          SBE37P3     247     582     1114
                                          AVTP        8037    747     1114
                                          SBE37PuP3   1230    749     1114
                                          SBE37       444     998     1114
                                          SBE37       440     1247    1114
                                          ROM 11      214     2003    1114
                                          ROM 11      26      3654    1114
                                          SBE37Pu     1607    3656    1114
                                          SBE26       257     3700    (1)

AW1241-1  55°31.94'S  3810   02.02.2005   AVTPO       9200    212     11(2)
          00°00.05'W         16:00        SBE37P3     246     317     1114
                             22.02.2008   AVTP        9785    424     1114
                             06:00        AVT         10532   770     1114
                                          SBE16P3     245     772     1114
                                          ROM 11      216     2017    1114
                                          SBE37       269     2000    (2)
                                          ROM 11      219     3744    1114
                                          SBE26       228     3810    (1)

AW1238-5  54°30.76'S  1700   01.02.2005   AVTP        10541   201     1114
          00°01.39'E         20:00        SBE16PuP3   1235    208     1114
                             21.02.2008   SBE37P3     244     257     1114
                             12:00        SBE37       218     306     1114
                                          SBE37PP35   2719    356     1114
                                          AVTP        9211    402     1114
                                          SBE37PP35   2720    403     1114
                                          SBE37       225     573     1114
                                          AVTP        7727    748     1114
                                          SBE37PP35   2722    750     1114
                                          SBE37PP35   2723    1000    1114
                                          SBE37       437     1250    1114
                                          ROM 11      215     1644    1114
                                          SBE37PP35   3811    1646    1114
                                          SBE26       227     1700    (1)


Tab. 2.6: Moorings deployed on the Greenwich meridian

Mooring   Latitude    Water  Date         Instrument  Serial  Instr.
          Longitude   Depth  Time         Type        Number  Depth 
                      (m)    1. Record                        (m)   
--------  ----------  -----  -----------  ----------  ------  ------
AW1232-9  68°59.74'S  3419   11.03.2008   ULS         57      150
          00°00.17'E         14:00        AURAL       085     216
                                          ADOP        6240    450
                                          AVT         9782    750
                                          ROM 11      144     1800
                                          SBE37       2086    3300
                                          ROM 11      486     3300

AW1231-8  66°30.68'S  4546   07.03.2008   ULS         56      150
          00°01.81'W         22:00        SBE37       1236    200
                                          SBE37       449     300
                                          SBE37       2088    400
                                          ADOP        825     450
                                          SBE37       2089    500
                                          SBE37       2090    600
                                          SBE37Pu     1237    700
                                          AVTP        10928   700
                                          SQ          30      850
                                          AVT         9180    1800
                                          SBE37       237     4500
                                          AVT         9186    4500

AW1230-6  66°01.13'S  3577   08.03.2008   AURAL       086     200
          00°04.77'E         14:00        AVTP        3517    200
                                          SBE37Pu     1229    200
                                          SBE37       2091    300
                                          SBE37       2092    400
                                          SBE37       2093    500
                                          SBE37       2094    600
                                          SBE37Pu     2237    700
                                          ROM 11      295     700
                                          AVTP        9188    1600
                                          SBE37       2099    3400
                                          ROM 11      504     3400

AW1229-8  63°58.03'S  5195   28.02.2008   ULS         64      150
          00°003.10'W        18:00        SBE37       2098    200
                                          SBE37       2096    300
                                          ADOP        5373    350
                                          SBE16       2416    400
                                          SBE37       2099    500
                                          SBE37       2100    600
                                          SBE37Pu     2396    700
                                          AVTP        10925   704
                                          SQ          29      850
                                          AVT         9390    2000
                                          SBE37       2101    5150
                                          AVT         10499   5150

AW1227-10  59°04.10'S  4630   25.02.2008  SBE37P1O    1565    4580
           00°04.88'W         14:00


Tab. 2.7: Moorings recovered along transect from Kapp Norvegia towards Joinville
          Island

Mooring   Latitude    Water  Date         Instrument  Serial  Instr.  Record
          Longitude   Depth  Time         Type        Number  Depth   Length
                      (m)    1. Record                        (m)     (days)
                             last Record
--------  ----------  -----  -----------  ----------  ------  ------  -------
AW1209-4  66°37.08'S  4860   01.03.2005   SBE37       3814     282    675
          27°06.29'W         12:00        SQ          W4       1840
                             18.03.2008   SBE16       319      4799   1113
                             12:00        SBE37       226      4848   1113
                                          ROM 11      101      4849   1113

AW1208-4  65°37.14'S  4740   05.03.2005   ULS         42       154    (1)
          36°23.53'W         21:00        ADOP        5691     291    (1)
                             21.03.2008   SBE37       241      296    1111
                             08:00        SQ          W5/19    2014
                                          SBE37       228      4678   1111
                                          SBE37       1606     4728   1111
                                          AVT         9182     4729   1111

AW1207-6  63°42.20'S  2500   14.03.2005   ULS         36       148    (1)
          50°52.22'W         04:00        AVTP        9193     246    (2)
                             27.03.2008   SBE37       3812     248    681
                             14:00        AVT         10929    757    1109
                                          POD         0403     1457   (1)
                                          SQ          W6/17    2000
                                          SBE37       239      2099   1109
                                          SBE37       3813     2297   688
                                          AVT         10497    2303   1109
                                          SBE37       2097     2488   1109
                                          AVT         10496    2489   1109




Tab. 2.8: Moorings deployed along transect from Kapp Norvegia towards Joinville
          Island

Mooring   Latitude    Water  Date         Instrument  Serial  Instr.
          Longitude   Depth  Time         Type        Number  Depth 
                      (m)    1. Record                        (m)   
--------  ----------  -----  -----------  ----------  ------  ------
AW1244-1  68°59.70'S  2927   13.03.2008   SQ          23      850
          06°56.70'W         16:00

AW1245-1  69°03.68'S  4466   15.03.2008   SQ          24      850
          17°25.89'W         16:00

AW1209-5  66°36.89'S  4864   18.03.2008   SBE 16      2415    300
          27°07.08'W         20:00        SQ          34      800
                                          SBE37P      220     4800
                                          SBE37       230     4850

AW1208-5  65°36.85'S  4770   21.03.2008   ULS         62      150
          36°24.43'W         16:00        ADOP        3813    300
                                          SBE16       1979    300
                                          SBE37       435     4680
                                          SBE37       2234    4730

AW1217-3  64°23.63'S  4456   24.03.2008   SQ          32      850
          45°52.38'W         14:00        SBE37       250     4150
                                          SBE37       240     4350
                                          ROM 11      296     4351

AW1216-3  63°54.03'S  3516   26.03.2008   SBE37       2392    3350
          49°04.68'W         16:00        SBE37       2393    3400
                                          SBE37       439     3450
                                          ACM 11      298     3451

AW1207-7  63°42.74'S  2500   27.03.2008   ULS         60      150
          50°50.55'W         20:00        AVTP        10872   250
                                          SBE16       2414    251
                                          AVT         10503   750
                                          SQ          36      850
                                          SBE37       2610    2100
                                          SBE37       2297    2200
                                          AVT         10530   2300
                                          SBE37       436     2490
                                          RCM 11      619     2490

AW1206-6  63°28.77'S  950                 ULS         61    150
          52°05.77'W                      AVTP        9206    250
                                          SBE37       1228    500
                                          AVT         9201    501
                                          SBE16       2422    700
                                          SBE37       438    900
                                          RCM 11      508    901


Abbreviations:

ADCP    RD-Instruments, Self Contained Acoustic Doppler Current Profiler
AURAL   AURAL-Underwater Acoustic Recorder
AVTCP   Aanderaa Current Meter with Temperature-, Conductivity- and Pressure 
        Sensor
AVTP    Aanderaa Current Meter with Temperature- and Pressure Sensor
AVT     Aanderaa Current Meter with Temperature Sensor
RCM 11  Aanderaa Doppler Current Meter
SBE16   SeaBird Electronics Self Recording CTD to measure Temperature, 
        Conductivity and Pressure
ULS     Upward looking sonar from Christian Michelsen Research Inc. to measure 
        the ice draft
SBE37   SeaBird Electronics, Type: MicroCat, to measure Temperature and 
        Conductivity
SQ      Sound Source for SO FAR-Drifter

Remarks:

Blank field: passive instrument with not data recording
(1) Data recorded but not processed
(2) Complete or partly missing data due to instrument failure

Location and recovering of moored instruments

Since ANT-XXI2 (2002) POSIDONIA has been proved as a reliable system to locate 
transponders or acoustic releases in moorings. POSIDONIA is an ultra short base 
line positioning system manufactured by iXSEA (France). The POSIDONIA signals 
can be detected even under unfavourable conditions, e.g. the high background 
noise created by Polarstern itself. Another advantage is the POSIDONIA 
transducer array which is installed in the moon pool. There the commands are 
transmitted from a fixed and stable platform resulting in a longer distance over 
which the signal can be received by the releaser because a handheld transducer 
lowered over the side vibrates while it is dragged through the water. It was 
observed that a mooring could not be released with the handheld transducer if 
the slant range is larger than 4,000 m while the same mooring was released with 
one single release ping only being sent via the POSIDONIA transponder array. 
During this cruise POSIDONIA was only able to display the relative target 
position because of a failure in the main electronic unit.

Under good weather and sea ice conditions 11 of 12 moorings were recovered 
without any serious difficulties. The first try to recover the southernmost 
mooring AW1233-7 at the Greenwich section failed. One of the double releasers 
and an additional transponder in the mooring top were equipped with POSIDON IA-
option but both could not be located while Polarstern was exactly at the 
estimated mooring position. Therefore the handheld transducer and the standard 
deck unit TT3O1 were used to interrogate the second releaser. This operation 
failed also. Several release commands were sent with POSIDONIA and TT3O1. An 
intensive search occurred from the bridge and with the helicopter downstream 
according to the observed sea ice drift. After 8 hours of searching the mooring 
was assumed as lost and Polarstern took course to the next working area.

All moorings were equipped with an ARGOS satellite transmitter which is supposed 
to send the position if a mooring would surface unplanned. These messages were 
automatically checked by OPTIMARE and forwarded by email. By this we were 
informed that the ARGOS transmitter with the ID 10574 which was installed in 
AW1233-7 has sent one reliable position message. The position was about 9 km 
downstream off the deployed mooring location. Two additional locations obtained 
from OPTIMARE confirmed the position given in the email and indicated a slow 
westward drift. The time of the first message received by ARGOS agreed with the 
time when the release commands have been sent.

Polarstern returned to the mooring guided the helicopter in a field of ice 
floes. Later the direction-finder detected the ARGOS signal too. Finally AW1233-
7 was recovered completely. The upper instruments and the mooring rope showed 
clearly the trace left by an iceberg. The rotor of the upper current meter was 
lost and the antenna of the ARGOS transmitter was pushed down through the 
fitting clamps. Therefore the antenna could not be stick out sufficiently of the 
water and only the satellite could receive the signal from above. The mooring 
had been hit and dragged off by an iceberg over a distance of more than 9 km and 
the release command was successfully received over a distance of about 10 km.

Altogether the 12 moorings were equipped with 119 instruments. Five of them were 
sound sources. The instruments were recovered in good conditions. The data from 
105 data memories were transferred to PC. The data processing occurred for 91 
instruments on board. The processing of the remaining 14 data records from ULS, 
Bottom Pressure Recorder and ADCP could not finished on board but the data 
seemed to be in good condition. Six instruments failed which results in a data 
recovery rate of 94%.

It was the first time moorings were deployed for a period of three years. Tab. 
2.5 and 21 indicate that most of the instruments have measured and stored during 
the complete mooring period. While all Aanderaa current meter contained the full 
data rate the Seabird SBE37 have recorded approximately 80 % only. This is 
surprising because it happened for the moorings which have been exchanged in 
2006 already. In the past SBE37 were working correctly for a period of two years 
with the same sampling setup. Therefore a bad quality of the batteries is the 
most probable reason. Another problem was related with SBE37 instruments with 
5N38##. These instruments are a new design which have internal pumps in contrast 
to the former ones with external pumps. Probably the internal pump needs more 
power. In future SBE37 sample rates should be 60 minutes for old and new design.


2.1.5 Argo in the Southern Ocean

Objectives

The international Argo project maintains order of 3,000 profiling floats 
distributed throughout the world ocean, to establish a real-time operational 
data stream of mid- and upper (< 2,000 m) ocean temperature and salinity 
profiles. In addition, the array provides the mid-depth oceanic circulation 
pattern. During the past years, AWI achieved technological developments to 
extend the operational range of Argo floats into seasonally ice-covered regions. 
To this end and with additional support by the EU project MERSEA and the BMBF 
Project German Argo, the NEMO float (Navigating European Marine Observer) was 
developed and tested, which is now fully operational (Klatt et al., 2007). NEMO 
floats are equipped with ISA-2, an ice-sensing algorithm which triggers the 
abort of a floats' ascent to the sea surface, when the presence of sea ice is 
likely as determined from the existence of a layer of near surface winter water. 
To nevertheless be able to (retrospectively) track the floats that actively 
remained under the sea ice, acoustic tracking via RAFOS (Rossby et al., 1986) 
(Ranging And Fixing Of Sound) is used. All NEMO floats are equipped with RAFOS-
receivers and an array of 10 moored sound sources has been installed.

Work at sea

Deployment of Argo floats

During ANT-XXIV/3 a total of 15 NEMO floats (Navigating European Marine 
Observer, produced by OPTIMARE, Germany) and one refurbished APEX float 
(produced by Webb Research Corporation, USA) were deployed in the Weddell Sea. 
In addition, 38 APEX floats - also equipped with RAFOS and ISA - provided by 
Steve Riser, University of Washington (UW), were deployed. The instruments
were launched at quasi-regular intervals along the Greenwich meridian and within 
the central and western part of the Weddell Sea proper, with preference given to 
undersampled regions and boundary currents (Fig. 2.16, Tab. 2.9 and 2.10). All 
of the float launches were preceded by a CTD cast.


Fig. 2.16: Deployment positions of Argo floats. (White dots - APEX floats 
           (University of Washington), red dots - NEMO floats (AWI), black dot - 
           APEX float (AWI))


All APEX floats (UW and AWI) are is equipped with RAFOS Navigation System and 
with Ice Sensing Algorithm (ISA; abort-temperature -1.79°C). The AWI APEX and 
nine of the UW floats using the ARGOS system for communication (marked with an A 
in Tab. 2.9), the remaining 29 UW are capable of using IRIDIUM. The UW (AWI) 
floats were ballasted to drift at a depth of 1,000 m (800 m) and will acquire 
profiles from 2,000 m to the surface.


Tab. 2.9: University of Washington APEX float launch positions and times. All 
          floats (excluding the first are equipped with Aanderaa opt des for 
          oxygen measurements.

          Float   Station   Latitude    Longitude    Date    Time   Depth
          Serial  [PS71/]                            (UTC)   (UTC)   [m]
          Number
          ------  -------  ----------  ----------  --------  -----  -----
          A 0051  101-6    42°20.74'S   8°59.13'E  14.02.08  03:42  4576
          A 5171  102-1    44°39.64'S   7°05.43'E  15.02.08  11:05  4614
          A 5285  103-2    45°59.86'S   5°52.86'E  16.02.08  04:05  3322
          A 5287  104-10   47°38.44'S   4°16.56'E  17.02.08  14:41  4548
          A 5281  106-2    48°54.72'S   2°47.90'E  18.02.08  06:30  4094
          A 5283  107-4    50°16.98'S   1°27.98'E  18.02.08  22:39  3804
          A 5282  108-4    51°29.97'S   0°00.02'W  19.02.08  11:52  2784
          A 5280  110-2    51°56.75'S   0°00.84'E  19.02.08  17:45  2858
          A 5288  112-3    52°30.23'S   1°23.75'W  20.02.08  03:28  2799
          5326    122-2    56°00.65'S   0°00.96'E  22.02.08  16:50  3495
          5327    125-3    56°58.03'S   0°01.02'E  23.02.08  08:33  3774
          5323    127-2    57°29.90'S   0°01.20'E  23.02.08  14:45  4059
          5313    128-2    58°00.49'S   0°00.12'W  23.02.08  23:07  4528
          5318    130-2    58°29.92'S   0°00.09'W  24.02.08  07:36  4187
          5307    132-4    59°04.30'S   0°05.60'E  25.02.08  14:04  4662
          5302    134-2    59°31.00'S   0°02.03'E  25.02.08  20:49  4780
          5320    135-2    60°00.46'S   0°00.21'W  26.02.08  04:19  5344
          5321    137-2    60°29.93'S   0°00.04'W  26.02.08  11:18  5355
          5308    138-2    61°00.13'S   0°00.48'E  26.02.08  18:47  5379
          5298    140-2    61°29.88'S   0°00.48'W  27.02.08  01:43  5377
          5325    141-3    61°59.97'S   0°00.03'E  27.02.08  09:27  5358
          5324    143-3    62°30.58'S   0°00.54'W  27.02.08  17:31  5337
          5301    144-2    63°00.06'S   0°00.28'E  28.02.08  00:34  5302
          5295    146-2    63°29.97'S   0°00.20'E  28.02.08  07:40  5236
          5331    149-2    64°30.10'S   0°00.12'E  29.02.08  04:35  4659
          5303    157-6    66°28.31'S   0°01.73'W  08.03.08  00:45  4493
          5310    159-5    66°01.43'S   0°07.81'E  08.03.08  15:10  3549
          5300    163-2    67°00.03'S   0°00.11'E  09.03.08  17:09  4702
          5329    167-3    68°00.00'S   0°00.06'W  10.03.08  07:30  4506
          5330    171-2    68°45.11'S   0°00.09'E  10.03.08  18:27  3622
          5317    192-2    66°56.75'S  25°17.07'W  17.03.08  22:03  4852
          5316    194-2    66°24.79'S  29° 1.05'W  19.03.08  20:39  4827
          5304    195-2    66°13.03'S  30°55.86'W  20.03.08  04:49  4810
          5311    196-2    66° 0.48'S  32°46.68'W  20.03.08  12:55  4789
          5305    197-2    65°48,54'S  34°37.55'W  20.03.08  21:01  4787
          5306    198-6    65°36,63'S  36°22.87'W  21.03.08  14:51  4770
          5299    199-2    65°27.20'S  37°42.44'W  21.03.08  21:47  4731
          5309    200-2    65°16.92'S  39° 1.09'W  22.03.08  04:05  4766


All NEMO floats are equipped with RAFOS Navigation System, an adjustable Ice 
Sensing Algorithm (ISA-2), set to -1.79'C with a 'retarded' response: Once 
activated, ISA-2 will need to detect 'surfacing conditions' (i.e. the lack of 
'abort conditions') for two consecutive ascent cycles, before giving the float 
permission to completely ascend to the surface on the second cycle. An interim 
data storage (iStore) stores any profiles that could not be transmitted in real 
time due to ISA aborts and transmits these profiles during ice-free condition. 
The floats were ballasted to drift at a drift depth of 800 m and will acquire 
profiles from 2,000 m to the surface.


Tab. 2.10: AWI float launch positions and times. All floats were equipped with 
           Ice Sensing Algorithm ISA-2, set to -1.79'C. Floats #120 - 134 are 
           NEMO floats, float #135 is an APEX float.

     FLOAT
AWI  SERIAL  ARGOS   WMO #   STATION  LATITUDE   LONGITUDE    DATE     TIME   DEPTH
 #     #      -DEC           [PS71/]     [S]                  (UTC)    (UTC)   [m]
---  ------  -----  -------  -------  ---------  ----------  --------  -----  -----
120   55     10120  7900232   147-4   63°58.04'  00°02.44'W  28.02.08  21:33  5196
121   49     08064  7900226   150-3   64°59.99'  00°00.01'E  29.02.08  11:00  3726
122   46     29223  7900224   152-3   65°29.97'  00°00.36'E  29.02.08  17:22  3972
123   25     27983  7900218   158-2   66°14.72'  00°01.22'W  08.03.08  04:39  3684
124   50     08067  7900227   161-7   66°30.07'  00°00.01'E  09.03.08  10:27  4546
125   54     09728  7900231   165-2   67°30.03'  00°00.10'E  10.03.08  00:18  4625
126   40     08060  7900223   169-2   68°30.05'  00°00.14'E  10.03.08  13:56  4256
127   36     28037  7900222   175-5   68°59.82'  00°00.14'E  11.03.08  13:29  3413
128   27     27985  7900219   184-3   68°59.59'  06°56.73'W  13.03.08  14:29  2924
129   58     08058  7900234   186-4   69°03.80'  17°26.53'W  15.03.08  15:24  4766
130   51     09354  7900228   188-2   68°23.55'  19°04.26'W  16.03.08  08:48  4827
131   31     28013  7900221   189-2   67°56.47'  19°59.98'W  16.03.08  17:53  4905
132   52     09355  7900229   190-2   67°35.84'  21°47.97'W  17.03.08  03:13  4904
133   56     10454  7900233   191-4   67°18.96'  23°38.27'W  17.03.08  14:10  4874
134   53     09363  7900230   193-12  66°34.66'  27°25.22'W  19.03.08  13:28  4861
135  2552     9356  7900235   207-4   64°23.06'  45°55.58'W  24.03.08  16:13  4442
  


2.1.6  Installation of RAFOS Sound sources

During this cruise, 5 sound sources were recovered and 7 sound sources deployed 
(Fig. 217, Tab. 211 and 212).


Fig. 2.17: Current state of the Weddell Sea RAFOS array. Red dots depict 
           positions where sound sources were deployed or redeployed during 
           ANT-XXIV/3. The black dots represent positions of sound sources 
           deployed during earlier cruises.

 
At locations Wi and W2, the recovered sources were immediately redeployed after 
a battery and clock check and the exchange of shackles and chains. At locations 
W4 and W6 the recovered sound sources (tuned to a deployment depth of 2,000 m) 
have been replaced by two new sources (tuned to a deployment depth of 800 m). 
Sound source W5 was flooded and has not been replaced. Finally, on three 
locations (W9, Wi 0, and Wi 1) sound sources have been deployed for the first 
time.


Tab. 2.11: Sound sources recovered 1) Note that for R29 and R30 the sources 
           internal software attempts to compensate for the noted clock drift by 
           adjusting the pong schedule. To be able to determine the effective 
           drift of the pongs, this adjustment needs to be accounted for. The 
           necessary information can only be retrieved after the next recovery 
           of the sources by reading the operations log file as stored on board 
           the source. Note the difference between GPS and UTC times.

site /     position       sound source status
mooring    water depth
pong time  recovery date
---------  -------------  ----------------------------------------------
Wlc/229    63°57.17'S     R29 @ 832 m; piggy-back, aluminum resonator
00:30 GPS  00°00.17'W     RTC 12:28:16 @ GPS 12:35:00 -> 392s late(1)
           5180 m         general status at recovery: ok
           28 Feb 2008    Vbat-2 = 8.56 Vdc
           12:07 UTC      High Voltage = 19.24 Vdc
                          Internal Pressure = 203.48 hPa

W2c/231    66°30.67'S     R30 @ 865 m; piggy-back, aluminum resonator
01:00 GPS  00°01.90'W     RTC 17:04:34 @ GPS 17:08:00 -> 206s late(1)
           4517 m         general status at recovery: ok
           07 Mar 2008    Vbat-2 = 8.57 Vdc
           16:50 UTC      High Voltage = 19.67 Vdc
                          Internal Pressure = 294.60 hPa

W4a/209    66°37.08'S     R16 @ 1840 m; in-line design, steel resonator
01:30      27°06.29'W     status: flooded
           4860 m         Vbat-2 = -
           18 Mar 2008    High Voltage = -
           16:09 UTC      Internal Pressure = -
         
W5a/208    65°37.14'S     R19 @ 2014 m; in-line design, steel resonator
00:30      36°23.53'W     RTC 10:59:24 @ G PS 10:57:00 ->144s early
           4740 m         general status at recovery: dry, CPU ok, no
           21 Mar 2008    pongs
           08:20 UTC      Vbat-2 = 7.7 (with Voltmeter, 1? puck)
                          High Voltage = 3.7 (with Voltmeter, 5 pucks)
                          Internal Pressure = ok but no pressure gauge

W6a/207    63°42.20'S     R17 @ 2000m; in-line design, steel resonator
01:00      50°52.22'E     RTC: pending
           2500           general status at recovery: pending
           pending        Vbat-2 = pending
           Pending        High Voltage = pending
                          Internal Pressure = pending


Tab. 2.12: Sound source moorings of ANT-XXIV/3. Sound source depths are nominal 
           depths according to preliminary mooring protocols. Note the 
           difference between GPS and UTC times.


site /     position       sound source status
mooring    water depth    
pong time  deployment 
           date
---------  -------------  ----------------------------------------------
W1d/229    63°58.03'S      R 29 @ 820 m; piggy-back design, aluminum
00:30 GPS  00°03.10'W      resonator
           5170m           toffset =0s
           28-02-2008      Vbat-2 = 8.56 Vdc
           17:31           High Voltage = 19.24 Vdc
                           Internal Pressure = 203.48 hPa

W2d/231    66°30.68'S      R 30 @ 869 m; piggy-back design, aluminum
01:00 GPS  00°01.81'W      resonator
           4517 m          Vbat-2 = 857 Vdc
           07-03-2008      High Voltage = 19.67 Vdc
           21:24           Internal Pressure = 294.60 hPa

W11a/244   68°59.10'S      W 23 @ 790 m; piggy-back design, aluminum
00:40 GPS  06°56.10'W      resonator
           2927m           Bat=+00439dV
           13-03-2008      Vac=+00044
           14:14

W9a/245    69°03.68'S      W 24 @ 800m; piggy-back design, aluminum
01:10 GPS  17°25.89'W      resonator
           4766 m          Bat=+0044idV
           15-03-2008      Vac=+0004i
           14:49

W4b/209    66°36.89'S      R 34 @ 837 m; piggy-back design, aluminum
01:30 GPS  27°07.08'W      resonator
           4860m           Vbat-2=8.11 Vdc
           18-03-2008,     High Voltage = 20.39 Vdc
           19:48           Internal Pressure = 661.86 hPa

W10/217    64°23.36'S      R 32 @ 836 m; piggy-back design, aluminum
00:40 GPS  45°52.38'W      resonator
           4400 m          Vbat-2 = 849 Vdc
           24-03-2008      High Voltage = 27.49 Vdc
           12:37           Internal Pressure: 991.15 hPa (sensor faulty, 
                           manual vacuum check Ok.

W6/207     63°45.10'S      R 36 @ 857 m (as planned)
01:00 GPS  50°54.30'E      with electronics R 19
           2500 m          Vbat-2 = 8.98 Vdc (as measured by #36)
           depi. pending   High Voltage = 20.55 Vdc (as measured by #36)
                           Internal Pressure = no sensor. (Manual vacuum
                           check Ok


Preliminary and expected results

The deployment 54 ARGOS floats into the Weddell Gyre increases significantly the 
number of active floats from 32 to 86. Thus, for the first time the requirements 
of the Argo project (floats spaced every 3°) are met (Fig. 2.18).


Fig. 2.18: Current distribution of Argo floats in the area of the Weddell gyre


References

Klatt, O., Olaf Boebel, and E. Fahrbach, 2007: A profiling float's sense of ice. 
    Journal of Atmospheric and Oceanic Technology, 24, 1301-1308. 
    DOI: 10.1175/JTECH2026.1

Rossby, T., D. Dorson, and J. Fontaine, 1986: The RAFOS-System. Journal of 
    Atmospheric and Oceanic Technology, 3, 672-679.



2.1.7 Iceberg tracking

To estimate the fresh water transport by icebergs, satellite tracked 
transmitters were deployed since cruise ANT-XVI/2 as iceberg markers. The 
project was supposed to end with a last deployment during cruise ANT-XXII/2 but 
one remaining transmitter was deployed during this cruise.

The marker determines its position once per day at noon with a GPS receiver. The 
positions are transmitted via satellite using the ARGOS system. The ARGOS 
transmitter is switched on for 6 hours once a week, to send the positions from 
the past seven days. The transmitter's on-time lasts long enough to ensure that 
all data can be received by CLS in Toulouse, France. This weekly transmission 
mode was chosen to save CLS service costs. The iceberg markers are designed to 
operate for up to two years. Due to environmental aspects, the housing is 
slightly enlarged compared to previous versions. Thus the new markers have 
positive buoyancy. Markers from melted icebergs are likely to leave the 
Antarctic Ocean by drifting northwards and being entrained into the Antarctic 
Circumpolar Current. Tilt sensors are installed to detect when an iceberg begins 
to capsize. The ARGOS transmitter will switch into a continuous mode as soon as 
the tilt exceeds a fixed limit.

The markers were deployed on icebergs by helicopter. A digital photograph was 
taken to describe the shape of the iceberg. The length and width was measured 
with the GPS, flying along and across the iceberg. The height above sea level is 
taken from the radar altimeter of the helicopter. Tab. 2.13 gives of the marked 
iceberg.

OPTIMARE, Bremerhaven, is assigned to collect the data from CLS via direct 
computer link and to process and validate the data.


Tab 2.13: Deployment of iceberg tracking ARGOS transmitter

          Transmitter                      Iceberg
          -------------------------------  ---------------------------
          ARGO  Date     Time   Latitude   length  width  Freeboard(m)
          S ID           (UTC)  Longitude    (m)    (m)
          ----  -------  -----  ---------  ------  -----  ------------
          9802  24.3.08  13:00  64°32.4'S    500    330       30
                                45°47.6'W    


Fig. 2.19: Track of the iceberg with marker Id 9802


2.1.8  Sea ice observations

Sea ice observations were conducted on an hourly basis by the CTD watch from the
bridge of Polarstern from 2 March to 29 March 2008 during daylight conditions 
(ca. from 05:00 to 21:00 UTC) when the ship was steaming. They are a 
contribution to the Antarctic Sea Ice Processes and Climate (ASPeCt) programme, 
which aims at an improved understanding of the role of Antarctic sea ice in the 
global climate system.

The sea ice thickness data collected in this framework form the only circumpolar 
ice thickness dataset available for the Southern Ocean and have been used for 
model validation studies. According to the ASPeCt protocol, total ice 
concentration, and the thickness, concentration and morphology (ridge height, 
areal fraction of ridged ice, floe size; snow thickness) of the three dominant 
ice types within a 1 km radius from the ship were recorded while the ship moved 
through the pack ice. The observations were complemented by records of sea 
surface temperature, near-surface air temperature, wind speed and direction, and 
total cloud cover. All together 236 observations were carried out, at 167 of 
them ice was encountered. All data collected were sent to the ASPeCt database 
immediately after the cruise.

As the cruise was conducted in austral summer, during the time of minimum ice 
extent, rather little sea ice was encountered. On our way to Neumayer Station no 
significant ice cover was encountered until we reached the coast.

However, the sea ice conditions in the Weddell Sea were extreme. Over the summer 
two large ice tongues stretched from the southern to the northeastern and the 
northwestern Weddell Sea (Fig. 220). This wider than normal ice extent is 
consistent with a trend visible in the time series of NSIDC derived from 
satellite images of increasing sea ice extent in summer during the last decades. 
However, this does not mean a real increase but only a weaker melting in summer 
because the winter sea extent remained basically constant.

It is of special interest, that the evaluation of satellite data by NSIDC 
indicated clearly that the Antarctic summer 2007/2008 was the one with the 
largest ice extent on record. This trend which is particularly strong in the 
Atlantic sector of the Southern Ocean is in clear contrast to the Arctic where a 
strong decrease of the summer ice extend is observed. To understand the opposing 
trends in the Antarctic and the Arctic is an obvious aim of our cruise.


Fig. 2.20: Regional sea ice distribution in the Weddell Sea on 18 March 2008 
           (www.seaice. de)



2.2   TRANSPORT VARIATIONS OF THE ANTARCTIC CIRCUMPOLAR CURRENT

      Carmen Böning, Olaf Boebel and Olaf Klatt 
      Alfred-Wegener-Institut

Objectives

Pressure Inverted Echo Sounders (PIES) deliver bottom pressure, bottom 
temperature and travel times of sound signals from the bottom to the sea 
surface, effectively providing a measure of average temperatures, bottom 
temperature and pressure variations and sea surface height.

PIES data are used to extract transport variations of the ACC as part of the AWI 
programme to observe the decadal variability of the Antarctic Circumpolar 
Current (ACC). PIES are placed along the GoodHope section between South Africa 
and Antarctica, which in large parts coincides with satellite ground track # 133 
of the Jason (previously TOPEX/Poseidon) satellite mission to allow direct 
comparison with altimetry data. PIES to PIES distances are selected to allow 
resolution of the major oceanic fronts of this region.

In addition, the same PIES data is used in the context of the GRACE satellite 
mission (Gravity Recovery And Climate Experiment), to validate monthly mean 
ocean bottom pressure anomalies as derived from the GRACE geoid variations. As 
the typical length scale inherent to GRACE data is about 1,000 km, the broad 
spatial coverage of the GoodHope PIES array (spanning nearly 2,000 km) is well 
suited to determine the accuracy of the GRACE measurements in this region. 
Additional PIES complement the array to the northwest.

Work at sea

Several of the PIES deployed from Polarstern in 2005/6 required an exchange in 
2008 to prevent the loss of the instruments due to a hardware error which was 
discovered only after the instruments' deployment and which would lead to early 
battery depletion. While 6 positions of the GoodHope and Grace PIES arrays were 
served by Polarstern, the 3 remaining sites were covered by the G.O. Sars during 
the 2007/8 AKES cruise.


Tab. 2.14: PIES recovery. Clock offsets are positive if early with regard to 
           UTC/GMT. *) PIES release/checkout from helicopter

moor  station  PIES  start     launch    launch lat  release   surface   surface lat  depth  Clock
-ing  book     Sn.   date &    date &    & Ion       date &    date &    & Ion         [m]   offset
      (rel.)         time      time                  time      time 
                     [UTC]     [UTC]                 [GPS]     [GPS] 
----  -------  ----  --------  --------  ----------  --------  --------  -----------  -----  --------
ANT-  PS 71/   189   25.08.06  26.08.06  37°05.56'S  11.02.08  11.02.08  37°04.09'S    4977   -165 sec
 3-1  097-1          15:06     15:13     12°46.16'E  09:42*    11:25     12°48.79'E            11.02.08
                                                                                              13:52:15

ANT-  PS 71/   113   26.01.05  26.01.05  41°08.12'S  13.02.08  13.02.08  41°08.56'S    4650   +99 sec
 5-1  099-3          16:12:56  19:20     09°56.62'E  03:43     05:35     09°57.18'E            16.02.08
                                                                                              16:16:21

ANT-  PS 71/   135   26.01.05  27.01.05  44°39.86'S  15.02.08  15:02.08  44°39.48'S    4536   +113 sec
 7-2  102-3          22:50:59  20:37     07°04.96'E  07:57     09:45     07°05.71'E            15.02.08
                                                                                              12:36:00

ANT-  PS 71/   125   29.01.05  30.01.05  47°39.30'S  17.02.08  17.02.08  47°39.23'S    4536   +78 sec
 9-1  104-7          17:06:12  02:29     04°15.70'E  11:32     13:14      4°16.11'E            17.02.08
                                                                                              15:29:00

ANT-  PS 71/   185   24.10.06  24.10.06  50°15.73'S  18.02.08  18.02.08  50°15.47'S    3888    Lost 
11-2  107-2          17:46:47  20:24     01°25.95'E  18:15*    19:48      1°26.31 E

ANT-  PS 71/   069   22.10.06  24.10.06  52°30.47'S  20.02.08  20.02.08  52°30.24'S    2736   -65 sec
13-1  112-2          14:58:12  06:17     01°25.12'W  02:09     02:52     01°22.27'W            20.02.08
                                                                                              11:30:30


During ANT-XXIV/3, 5 of 6 PIES were successfully recovered (Tab. 214) while one 
was lost during recovery. This PIES (#185 of mooring ANT-1 1.2) was lost after 
it had successfully surfaced. It floated next to the ship to be retrieved when 
it drifted astern and probably got smashed under the ships stern due to wave 
action.


Tab. 2.15: Helicopter assisted PIES recoveries. Sonobuoys were dropped from a 
           helicopter from a height of 1000 ft and acoustic data recorded via 
           radio link. Data dropouts are probably due to shielding of the 
           antenna by the helicopter's fuselage. 12 and 12.5 kHz pings are 
           generated by the PIES and release units

mooring      Sonobuoy   launch date  Sonobuoy            records        water  
 site         launch      & time                                        depth
            lat & lon     [GPS]                                          [m]
----------  ----------  -----------  --------------  -----------------  -----
ANT-3-1     37°05.56'S   11.02.08      channel 5     none (user error)  4977
            12°46.16'E   09:42         (received)
ANT-5-1     41°08.12'S   12.02.08      channel 7       17:17 - 17:42    4650
            09°56.62'E   17:17         (received)
ANT-11-1-2  50°15.73'S   18.02.08      channel 5       18:04 - 18:29    3888
            01°25.95'E   18:04         (failed)
                                       channel 8 (ok)

At two sites, PIES releases were executed some 20 nm ahead of Polarstern via an 
hydrophone lowered from a helicopter hovering above the water. During these, and 
on a third site, the PIES acoustic activity was monitored previous to and during 
release via sonobuoys, kindly provided by the Forschungsanstalt for Wasserschall 
und Geophysik, Kiel, Germany, dropped from the helicopter (Tab. 2.15). Details 
of this procedure are described in the cruise report of ANT-XXII/3. In this 
context it was particularly useful to have the PIES transmission schedules set 
to 10 minutes intervals for rather than half hourly, for acoustic verification.


Fig. 2.21: Positions of PIES deployments during Polarstern cruise ANT-XXIV/3 
           (white dots) and G. 0. Sars cruise AKES 2 (yellow dots). Red circles 
           indicate PIES with PopUp buoys attached. Red line: ground track #133 
           of Jason satellite mission (previously TOPEX/Poseidon). White dotted 
           lines: nominal positions of fronts: STF = Subtropical Front, SAF = 
           Subantarctic Front, PF = Polar Front, SACCF = Southern Antarctic 
           Circumpolar Current Front. White cross: recovery site of PIES at 
           position ANT- 13.1, re-deployment at position ANT- 13.2 on Greenwich 
           meridian.


Three of the PIES were re-deployed after refurbishment on board (exchange of 
batteries, software upgrades and hardware fixes). Along with additional 
deployments of two new PIES, a total of 5 PIES was deployed across the ACC (Tab. 
2.16 and Figs 2.21 and 222) at sites ANT-5, 7, 9, 11, and 13. At site ANT-3, a 
PIES (#192) with two PopUps was successfully deployed by G.O.Sars, only hours 
after Polarstern recovered the mooring ANT-3.1 at the same position.


Tab. 2.16: PIES deployments

moor-  Station  PIES  start     launch    launch      POSIDONIA: POSIDONIA:  POS. depth  PopUp  Auto
Ing     book    S/N   date &    date &    lat & lon   bottom     bottom lat  ID   [m]           release
      (deploy)        time      time                  date &     & lon                          date &
                      [GPS]     [GPS]                 time                                      time
                                                      [GPS]                                     [UTC]
----  --------  ----  --------  --------  ----------  ---------  ----------  ---  -----  -----  --------
ANT-     PS      062  10.02.08  13.02.08  41°07.35'S  13.02.08   41°07.4'S   470  4675     -    12.02.12
5-2   71/99-1           15:29     01:50    9°57.32'E    02:10    09°57.70'E                -      12:00

ANT-     PS      184  13.02.08  15.02.08  44°38.90'S     no      44°39.65'S  387  4616     #5   14.02.12
7-3   71/102-1          15:54     05:37    7°05.91'E  reception  07°06.20'E               #19     04:15

ANT-     PS      113  16.02.08  17.02.08  47°39.41'S     no      47°39.35'S  388  4538     -    17.02.12
9-2   71/104-5          16:20     09:42    4°15.69'E  reception  04°15.70'E                -      02:00
  
ANT-     PS      189  18.02.08  18.02.08  50°15.47'S  18.02.08   50°16.12'S  386  3844    #14   18.02.12
11-3   71/107-2         20:55     19:20   01°26.33'E    20:08    01°26.72'E               #18     02:00

ANT-     PS      125  19.02.08  21.02.08  53°31.25'S  21.02.08   53°31.19'S  471  2632     -    20.02.12
13-2   71/115-1         14:37     01:13   00°00.09'E    01:45    00°00.23'E                -      02:00


Fig. 2.22: Hydrosweep depth profile (black) along ground track #133 (obtained 
           during ANTXXII/3) with a resolution of 1,000 m. Red dots indicate 
           PIES positions ANT-3, -5, -7, -9, -11, and -13. The grey curve 
           indicates topography according to Smith and Sandwell TOPEX/Poseidon 
           analysis.


Preliminary results

From four of the five successfully recovered PIES continuous time series with 
half hourly data were obtained. PIES #189, recovered at site ANT-3, shows data 
gaps of a few cycles (up to days) in the beginning of the measurement and has a 
large gap of one and a half month starting in the middle of December 2006. 
Examination of the log-file revealed unknown problems to have caused repeated 
self-resets of the instruments CPU. After 4 May 2007 however, the PIES operated 
flawlessly and provided half hourly measurements until its recovery on 11 
February 2008. PIES #185, which had been lost during recovery, had fortunately 
previously transmitted some of its data via a PopUp buoy, so 6 data-months of 
the 18 data-months record are available.

Pressure time series of all instruments show a clear tidal signal and the 
fortnightly modulation of the tides (Fig. 223). On a monthly time scale, the 
variability of the pressure time series measured at positions south of ANT-3 is 
of about 0.05 to 0.1 dbar, decreasing from North to South. This range compares 
well with the range of variability as derived from (satellite based) GRACE 
solutions. The highest bottom pressure variability of about 1 dbar was found at 
site ANT-3, and is caused by the substantial sea surface height difference of 
more than 1 m between cyclonic and anticyclonic eddies, which are omnipresent in 
the Cape Basin. Three of the bottom pressure time series, however, show 
conspicuous drifts, which have not yet been removed and need to be analysed in 
more detail in the lab.


Fig. 2.23: Absolute pressure, temperature anomalies and travel time measured by 
           PIES #113 at ANT-5. 1. Blue: unfiltered 30-min values. Red: 2-day low 
           pass filter. Yellow: 30-day low pass filter. Black: 180-day low pass 
           filter.


The observed range of the bottom temperature anomalies is, on a daily time 
scale, ± 0.01°C. On longer time scales, the time series show a period of 10 - 
14 months and about half the amplitude.


Fig. 2.24: Blue dots indicate the position of the POSIDONIA transponder during 
           the recovery (top) and deployment (bottom) at ANT-5. Red line: 
           release signal sent


The acoustic travel time varies by up to 0.02 sec on time scales typical for 
mesoscale features. Those instruments moored at depths of 4000-5000 m showed 
clear travel time signals (and did hence well receive the acoustic pings), while 
PIES #69, moored at a depth of 2736 m, provided a diffuse travel time signal 
only. Further analysis of this instrument will be needed to resolve if this was 
due to the PIES electronics or rather a depth-related issue.


Tab 2.17: PIES ascent or descent and buoyancy information

Position  R/D  PIES  Posi-  Posi-    w     release     release     Anderaa  Floata-  Buoy-
               S/N   donia  donia  [m/s]   sent                    DCS      tion     ancy
                     S/N    data
--------  ---  ----  -----  -----  -----   ----------  ----------  -------  -------  ------
ANT-3-1    R   189    470     n                                    n        j         19
ANT-5.2    D    62    470     j     1.01                           n        j        -35.34
ANT-5.1    R   113    387     j    -0.84   13.02.200   13.02.200   n        n         16
                                           8 03:43:00  8 04:00:00  
ANT-7.3    D   184    387     j     1.12                           S/N 753  j        -45.34
ANT-7.2    R   135    388     j    -0.8    15.02.200   15.02.200   n        n         16
                                           8 07:57:00  8 08:13:00
ANT-9.1    R   125    386     n                                    n        n         16
ANT-9.2    D   113    388     j     1.26                           n        n        -60.34
ANT-11.2   R   185    462     n                                    n        n         16
ANT-11.3   D   189    386     j     1.38                           n        n        -70.34
ANT-13.1   R   69     471     j     not    20.02.200   not         n        n         16
                                    valid  8 02:09:00  valid
ANT-13.2   D   125    471     j     1.36                           n        n        -60.34
 

Critical to the planning of helicopter assisted PIES releases, but also to the 
overall expedition planning, are times of ascent and descent when instruments 
are deployed and recovered, respectively. To obtain quantitative estimates of 
these times for the various PIES/PopUp configurations used, range information 
(Fig. 224) from POSIDONIA transponders (which are part of all PIES moorings) 
have been analyzed in detail (Tab. 217), showing descent speeds to range from 1 
to 1.4 ms(^-1). A generalized approach, showing the descent speed as a function 
of system weight (Fig. 225 upper left corner) allows prediction of descent time 
for future deployments of variable total weight. Released PIES without 
additional floatation attached showed an ascent speed of 0.8 to 0.84 ms(^-1).


Fig. 2.25: Speed of ascent and descent and of PIES' as a function of system 
           configuration



2.3  MONITORING THE ACC TRANSPORT THROUGH DRAKE PASSAGE

     Christine Provost(1), Jae Hak Lee (2),            (1)LOCEAN
     Michael Beauverger(1), Annie Kartavtseff(1),      (2)KORDI
     Hervé Legoff(1), Thierry Monglon(1), 
     Sang Chul Hwang(2)

Objectives

The Antarctic Circumpolar Current (ACC), the world largest current, is a key 
element of the global climate system. The ACC is constricted to its narrowest 
extent (700 km) in Drake Passage thus a convenient place for observations. 
Monitoring the transport and water mass characteristics of the ACC is essential 
for understanding the coupling of this major current with climate change. It is 
not an easy matter since the current is concentrated in highly variable narrow 
bands of swifts currents and energetic eddies of all sizes are numerous.

Our experimental set up is designed to use the complementarity between satellite 
and in-situ observations. Satellite altimetry measures the sea level of the 
ocean along tracks every 10 days with horizontal resolution of 7 km. The in-situ 
measurements will provide information on the vertical structure of the ocean, 
information that cannot be obtained by satellites.

During ANT-XXII/3, in January-February 2006, we deployed an array of 10 current 
meter moorings along a ground track of Jason altimetric satellite (Fig. 226).


Fig. 2.26: Location of the 10 moorings deployed during ANT-XII/3 in January 
           February 2006.  Background is bottom topography (in m). The narrow 
           ridge to the south west of M6-M7, part of the Shackleton Fracture 
           Zone, constrains the ACC flow.


Work at sea

The work at sea included: recovery of the moorings deployed in 2006 (Tab. 2.18), 
deployment of 5 new moorings (Fig. 227 and 2.28, Tab. 2.19) at the locations Ml 
through M5 where the Antarctic Circumpolar Current is canalized due to the steep 
and narrow ridge of the Shackleton Fracture Zone and realization of a refined 
array of CTD stations with LADCP along the satellite ground track.

The two moorings to the south M10 and M9 which were equipped with double benthos 
releases were safely recovered. The remaining 8 moorings carried a transducer 
equipped with POSIDONIA (Ml through M8) and could be located readily. However 
two of them M2 and M8 could not be recovered. They were released, the acoustic 
transducers went up from their moored positions (respectively 3,070 m for M2, 
2,600 m for M8) and then stabilized around 1,200 m at M2 and 1,600 m at M8. In 
both cases, the moorings, once stabilized, began to drift with the current. In 
spite of dredging efforts (1 full day for M8, and more than half a day for M2) 
the two moorings could not be recovered. During the two attempts wind and sea 
surface state conditions were rather poor.

M7 slowly went up to the surface. We recovered it and discovered that part of 
the foam flotation had imploded. M6, M5, M4, M3 and Ml were fully recovered. The 
instruments were read on board.


Tab. 2.18: Data recovered

           Mooring  Instrument  Depth   record          CTD/LADCP
                                                        stations
           -------  ----------  ------  --------------  ---------
           Ml       ADCP         200 m  26 months       PS71/252
                    Aquadopp     500 m  26 months       PS71/253
                    RCM8         500 m  26 months
                    Microcat    l000 m  26 months
                    RCM11       l000 m  26 months

           M2 lost  

           M3       ADCP         400 m  26 months       PS71/248
                    microcat     400 m  26 months       PS71/249
                    Aguadopp     900 m  26 months
                    RCM8         900 m  26 months
                    RCM8        1950 m  26 months
                    MORS        3100 m  26 months

           M4       RCM8         400 m  26 months
                    Microcat     400 m  26 months       PS71/244
                    Aguadopp     950 m  26 months
                    RCM7         950 m  26 months
                    RCM8        2450 m  26 months

           M5       Aguadopp     500 m   0 (head lost)  PS71/241
                    MORS         550 m  26 months
                    Microcat    1070 m  26 months
                    RCM7        1070 m  26 months
                    RCM8        2640 m  26 months

           M6       Aguadopp     300 m  26 months       PS71/237
                    MORS         300 m  26 months     
                    microcat     800 m  26 months
                    RCM7         800 m  26 months
                    RCM8        2440 m  26 months

           M7       Aguadopp     450 m   0 (crushed)
                    RCM7         450 m  21 months       PS71/236
                    microcat     950 m  21 months     
                    RCM8         950 m  21 months
                    RCM8        2540 m  26 months

           M8 Lost  

           M9       RCM-8        500 m   0 (leak)
                    RCM-11      1000 m  26 months       PS71/230
                    RCM-11      2500 m  26 months     

           M10      RCM-11       500 m  14 months       PS71/226
                    RCM-11      1000 m  26 months
                    RCM-11      1500 m  11 months
     
     
Tab 2.19: Moorings deployed

          Mooring               Instrument  Depth   CTD/LADCP stations
          --------------------  ----------  ------  ------------------
          M1-2:                 ADCP         500 m  PS71/252
          12/04/2008 18:00 UTC                      PS71/253
          Lat: 55°10.16'S       microcat     500 m
          Lon: 65°11.22'W       Aguadopp     500 m
          Depth: 1600 m         microcat    1000 m
                                Aguadopp    l000 m

          M2-2:                 microcat     500 m  PS71/256
          13/04/2008 15:50 UTC  Aguadopp     500 m
          Lat: 55°43.135'       microcat    l000 m
          Lon: 64°24.100'W      Aguadopp    l000 m
          Depth: 3816 m         RCM-8       2000 m
                                RCM-8       3000 m

          M3-2:                 ADCP         500 m  PS71/248
          10/04/2008 20:18 UTC  microcat     505 m  PS71/249
          Lat: 56°06.05'        Aguadopp     510 m
          Lon: 63°43.93'        microcat    1000 m
          Depth: 4275 m         RCM-7       1000 m
                                RCM-8       2000 m
                                RCM-8       3000 m

          M4-2                  RCM-11       500 m  Super  station
          08/04/2008 22:24 UTC  RCM-11      1500 m  DRAKE-4
          Lat: 56°55.55'S       RCM-11      2500 m  PS71/244
          Lon: 62°22.03'W 
          Depth: 4093 m

          M5-2                  RCM-11       500 m  Super  station
          07/04/2008 15:36 UTC  RCM-11      1500 m  DRAKE-3
          Lat: 57°37.53'S       RCM-11      2500 m  PS71/241
          Lon: 60°55.01'W 
          Depth: 3445 m


Fig. 2.28: Moorings deployed in Drake Passage



2.4  MEASUREMENTS OF TRACE GASES: CHIOROFLUOROCARBONS, HELIUM ISOTOPES & NEON

     Madlen Gebler, Alexandra Gronholz, Oliver Huhn 
     UP, Bremen

Objectives

The Weddell Sea is a major supplier for Antarctic Bottom Water to the 
World Ocean. There, Weddell Sea Deep and Bottom Water (WSDW and WSBW) 
are formed by interaction of mid-depth water masses with several shelf 
water types (e.g., Ice Shelf Water, ISW, or glacial melt water) and by 
entrainment of external water masses. Modifications in its composition 
and formation rates - caused by environmental changes (e.g., decay of 
ice shelves, warming mid-depth water) - could modify the strength of 
the Meridional Overturning Circulation (MOC) and, thus, affect climate 
and climate change. Changes in the formation processes and in the 
amount of formed deep and bottom water might also influence the uptake 
and storage of carbon in the interior of the Southern Ocean.

The major aims of our tracer measurements are:

• To assess the formation rates and its variability of WSDW and WSBW.
• To consider correlations to changing environmental conditions 
  (i.e. degradation of ice shelves, enhanced melting, warming, 
  freshening) that might lead to varying deep and bottom water 
  composition, distribution, and formation rates
• To determine the variability of deep and bottom water export and 
  import from easterly sources across the Greenwich meridian.
• To assess the contribution and variability of Southeast Pacific 
  Deep Slope Water (SPDSW) through Drake Passage to the total transport 
  of the Circumpolar Current.

The deep and bottom water formation and its variability in the Weddell 
Sea will be studied by using chlorofluorocarbon (CFC) inventories and 
CFC based transit time distributions (TTD5, ore age spectra), inferred 
from this cruise and from historical data. The combined hydrographic, 
CFC and noble gas data will allow to distinguish different source water 
masses, that contribute to deep and bottom water formation, and how 
they reflect changing environmental conditions. From the continuation 
of the CFC time series along the Greenwich meridian, further insight 
regarding the variability of the export of deep and bottom water out of 
the Weddell gyre and through the South Scotia Ridge system as well as 
the import from easterly sources is expected. The role of the SPDSW in 
the Atlantic Circumpolar Current will be studied by the repeated noble 
gas, CFC, and velocity observations across Drake Passage.

Work at sea

During the cruise a total of 1620 samples on 97 CTD/water bottle 
stations were collected for chlorofluorocarbons (CFC-1 1 and CFC-1 2); 
32 stations were occupied along the Greenwich meridian section, 37 
stations along the Weddell Sea section, and 28 stations across the 
Drake Passage. The water samples from the CTD/rosette system were 
collected into 100 ml glass ampoules and sealed off after a CFC free 
headspace of pure nitrogen had been applied. The CFC samples will be 
analysed in the CFC-laboratory at the IUP in Bremen. The determination 
of CFC concentration will be accomplished by purge and trap sample pre-
treatment followed by gas chromatographic (GC) separation on a 
capillary column and electron capture detection (ECD). The amount of 
CFC degassing into the headspace will be accounted for during the 
measurement procedure in the lab. The system will be calibrated by 
analyzing several different volumes of a known standard gas. 
Additionally the blank of the system will be analyzed regularly.

Furthermore, 480 samples from 41 stations were collected for helium 
isotopes (3 He, 4 He) and neon (Ne); 10 stations along the Greenwich 
meridian section, 14 stations along the Weddell Sea section, and 17 
stations across the Drake Passage. The water samples from the water 
bottles were stored in clamped off copper tubes. They will be analysed 
with the IUP-Bremen noble gas mass spectrometer (combined quadrupole 
and sector field mass spectrometer), after the gases were extracted 
from the sea water samples and separated from other gaseous components 
by several cooling traps.

Additionally, 50 samples from 6 stations (on the southern part of the 
Greenwich meridian section and above the northwestern slope along the 
Weddell Sea section) were collected for tritium (3H). The water samples 
were collected into water vapour tight glass bottles. Since tritium is 
part of the water molecule, all gasses will be
extracted from the water sample, and the remaining water will be stored 
for at least half a year. During that time a sufficient part of the 3H 
has decayed to 3 He. Finally, the 3 He is measured with the same IUP-
Bremen mass spectrometer as described above.

Expected results 

Chlorofluorocarbons (CFC5) are gaseous, anthropogenic tracers that 
enter the ocean by gas exchange with the atmosphere. The evolution of 
these transient tracers in the ocean interior is determined by their 
temporal increase in the atmospheric and by the formation and mixing 
processes of intermediate, deep and bottom water. The total inventories 
of CFC5 in deep and bottom water reflect the accumulation of CFCs 
carried by its surface near source water masses. Together with the 
known atmospheric CFC evolution, CFC inventories allow, thus estimating 
the renewal or formation rates of recently formed bottom water. 
Furthermore, the availability of time series from various sections 
allow to assess the temporal variability of the formation rates, and 
possibly, its relation to changing environmental (boundary) conditions 
(ice shelf decay, surface water warming, etc.).

Other methods using CFC5 as age tracers include transit time 
distributions (TTD5, or age spectra). By applying a "mean age", a 
"width of the age", and, if appropriate, a tracer free (i.e. "old") 
component, this dating method accounts for advection and mixing, other 
than the "CFC-ratio age" approach, which accounts - as a first approach 
- for advection and tracer free dilution only. This improves the 
estimates of ventilation time scales, mixing parameters, and 
ventilation or formation rates significantly. To constrain the 
parameters of the TTD well, it is valuable to use transient tracers 
from different observation times (e.g. CFC time series). Furthermore, 
the derived TTDs can be used to estimate the input, internal transfer, 
and storage of anthropogenic CO2.

Using stable tracers like helium isotopes and neon, additional to 
temperature and salinity, allow one to carry out an Optimum 
Multiparameter (OMP) analysis to estimate the contributions of the 
parent source water masses to the formation of deep water masses. 
Herein helium and neon are ideal tracers to detect smallest fractions 
of glacial melt water or ISW, and the 3He/4He isotope ratio is a tracer 
for deep water from the Pacific (SPDSW).


                                   ANT XXIV/3
                   Data Report: CFC and noble gas measurements

                           Oliver Huhn, Monika Rhein

                           RV Polarstern, ANT XXIV/3
             Cape Town - Prime Meridian, Weddell Sea - Punta Arenas
                         08. February - 16. April 2008

                      Chief Scientist: Eberhard Fahrbach

Principle Investigator: Oliver Huhn, Monika Rhein
Cruise participants:    Oliver Huhn, Madlen Gebler, Alexandra Gronholz
CFC measurements:       Klaus Bulsiewicz

Contact:                Oliver Huhn
                        Universität Bremen
                        Institut für Umweltphysik (IUP) - Ozeanographie
                        Institute of Environmental Physics (IUP) - Oceanography
                        Otto-Hahn-Allee 1
                        D-28359 Bremen, Germany

                        Tel.:  +49 - 421 - 218 62155
                        FAX:   +49 - 421 - 218 62165
                        Email: ohuhn@physik.uni-bremen.de

Datafile (ascii):

ANT-XXI4/3
2008-02-08-to-2008-04-16
Station
Cast
Bottle number
Bottle depth
Latitude
Longitude
CFC-11 [pmol/kg]
CFC-11-Flag
CFC-12 [pmol/kg]
CFC-12-Flag

The tracer data set was carefully checked for accurate measurements and 
outliers. According to the WOCE standards the following flags were applied to 
each measurement:

flag 2 = good
flag 3 = doubtful
flag 4 = bad
flag 6 = mean of replicates
flag 9 = no measurement (then, the data value is set to -9.000)


Methods

During the cruise a total of 1620 samples on 97 CTD/water bottle stations were 
collected for chlorofluorocarbons (CFC-11 and CFC-12); 32 stations were occupied 
along the Greenwich Meridian section, 37 stations along the Weddell Sea section, 
and 28 stations across the Drake Passage. The water samples from the CTD/rosette 
system were collected into 100 ml glass ampoules and sealed off after a CFC free 
headspace of pure nitrogen had been applied. The CFC samples will be analysed in 
the CFC-laboratory at the IUP in Bremen. The determination of CFC concentration 
will be accomplished by purge and trap sample pre-treatment followed by gas 
chromatographic (GC) separation on a capillary column and electron capture 
detection (ECD). The amount of CFC degassing into the headspace will be 
accounted for during the measurement procedure in the lab. The system will be 
calibrated by analyzing several different volumes of a known standard gas. 
Additionally the blank of the system is analyzed regularly.

Chlorofluorocarbons (CFC-11, CFC-12)

The Chlorofluorocarbon (CFC-11 and CFC-12) water samples from the CTD-bottle-
system are stored in glass ampoules without contact to the atmosphere during the 
tapping. Immediately after sampling the ampoules are flame sealed after a CFC 
free headspace of pure nitrogen had been applied.

The loss of CFCs into the headspace is considered by a careful equilibration 
between liquid and gas phase under controlled conditions before the sealed 
ampoules are opened and a precise measurement of the volume of the headspace. 
The determination of CFC concentrations in the IUP Bremen gas chromatography lab 
is accomplished by purge and trap sample pre-treatment followed by gas 
chromatographic (GC) separation on a capillary column and electron capture 
detection (ECD). The system is calibrated by analyzing several different volumes 
of a known standard gas. CFC concentrations are calibrated on SIO98 scale (Prinn 
et al., 2000). A more detailed description of the measurement system is given by 
Bulsiewicz et at. (1998).

  Bulsiewicz, K., H. Rose, O. Klatt, A. Putzka, W. Roether (1998). A capillary-
  column chromatographic system for efficient chlorofluoromethane measurement in 
  ocean waters. Journal of Geophysical Research, Vol. 103 (C8), 15959-15970, 
  DOI: 10.1029/98JC00140.

  Prinn, R. G., R. F. Weiss, P. J. Fraser, P. G. Simmonds, D. M. Cunnold, F. N. 
  Alyea, S. O'Doherty, P. Salameh, B. R. Miller, J. Huang, R. H. J. Wang, D. E. 
  Hartley, C. Harth, L. P. Steele, G. Sturrock, P. M. Midgley, A. McCulloch  
  (2000). A history of chemically and radiatively important gases in air deduced 
  from ALE/GAGE/AGAGE. Journal of Geophysical Research, Vol. 105, 17.751-17.792, 
  DOI: 10.1029/2000JD900141.


Accuracy (i.e. uncertainties of calibrated sample volume, calibration curve, 
extraction efficiency, standard and working gas, water blank, etc.):

CFC-12 < 1.8 %
CFC-11 < 2.8 %

Precision (i.e. mean error from 19 replicate samples):

CFC-12 < 0.007 pmol/kg or < 0.9% (which ever is greater) (n=6)

We do not give a value for the precision of CFC-11. Offline sample chromatograms 
regularly show a negative peak in the vicinity of the CFC-11 peak, which 
decreases the accuracy of CFC-11 in comparison to CFC-12, and which does not 
allow giving an objective estimate of a precision for CFC-11. CFC-11 data 
between stations 140 and 193 (south of 61°S on the Prime Meridian and east of 
28°W on the Weddell Sea section) are not reliable due to a possible hidden peak 
below the CFC-11 peak and possible problems with the measurement unit during 
that time (K. Bulsiewicz, personal communication, 2010). We flag these CFC-11 
data generally as doubtful (3). 

Acknowledgment

Sampling on board and measurement of CFCs and noble gases at the IUP Bremen was 
funded by the Deutsche Forschungsgemeinschaft within the SPP 1158 
"Antarktisforschung", grant RH 25/32. We thank Eberhard Fahrbach, Gerd Rohard 
and the scientific party to participate in the ANT XXIV/3 expedition and for the 
excellent assistance and cooperation on board. We thank also master and crew of 
RV Polarstern.



2.5  OXYGEN MEASUREMENTS

     Ismael Nünez-Riboni(1), Hein de Baar(2),     (1)Alfred-Wegener-Institut
     Marielle Lacombe(3), Charlotte Lohse(1),     (2)NIOZ
     and Gerd Rohardt(1)                          (3)CNRS LEGOS
		

Oxygen measurements from samples

To calibrate the oxygen profiles measured with the optode sensor of 
both CTDs, from AWI and NIOZ, water samples of the Niskin bottles of 
both CTD5 were taken from station 97 to station 251. One sample 
of water was taken at the surface, one at the ocean bottom and one at 
the oxygen minimum. Additional samples were taken along the water 
column: one sample each thousand meters. In most of the cases, 5 
or 6 water samples were taken from each cast. In shallow stations 
only 2 or 3 samples were taken. Every sixth CTD cast, replicas were 
taken (i.e., at least 15 % of the all the samples are replicas). 
In total, 651 samples were taken.

The oxygen was measured using the Winkler method, according to the 
manual "WOCE operation and methods" (C.H. Culberson, July, 1991). 
Immediately after the sampling, the dissolved oxygen was fixed with 1 
ml of MnCl2·4H2O and 1 ml of NaOH+Nal. Then, the bottles were stored 
under water and their caps were attached with a rubber band to prevent 
intrusion of air. To measure the dissolved oxygen, 1 ml of Sulphuric 
Acid 50% (H2504) was added to the samples and a solution of Sodium 
Thiosulfate (Na2S2O3·5H20) was titrated with a Dosimat Metrohm 
automatic pipette provided with a transmissiometer. Potassium iodate 
(KIO3) was used as standard. Preliminary results of these measurements 
show an accuracy of 0.028 ml l(-1) (based on the standard deviation of 22 
replicas).

While the AWI CTD sensor seems to be relatively stable (constant 
offset), the NIOZ CTD sensor drifted with time, measuring less oxygen 
every day, see Fig. 2.29. Due to problems with the Dosimat (failure of 
the device to measure some samples, bubbles in the pipette, etc.), the 
first half of the expedition (up to 10 March, i.e., station 163) 
results of the titration were not completely satisfactory: imprecise 
outcome of the titration resulted in a large dispersion of the offset 
around a straight line. After various attempts of improving the 
measuring process, on 10 March, the titer bottle and the pipette were 
changed; new titer was prepared, added to the bottle and standardized. 
After this, the titration results matched the CTD profiles along the 
vertical considerably better.

Monitoring of the offset between CTD and titration results ruled the 
sampling frequency of each CTD, depending on the dispersion of the off-
set around the straight line. Because of this, the first half of the 
expedition, samples were taken from every cast of both CTDs. After the 
offset seemed to be stable, and considering that the AWI CTD5 occurred 
with a large frequency, samples were taken only from one cast per day. 
Since casts of the NIOZ CTD occurred every second or third day, every 
cast of the NIOZ CTD has been sampled.


Fig. 2.29: Oxygen difference between the measured samples and the reading 
           from the CTD's oxygen sensor versus station number for the AWI 
           and NIOZ system




Three individual steps of correction were applied for the AWI CTD oxygen sensor: 

1. Step: Linear correction of the CTD oxygen reading
OXYl = a + b * OXY
with: 
a = -0.02291300577 
b =  1.029883905

2. Step: Linear correction of the oxygen sensor drifts
∆OXYl = a + b * Stationnumber
with: 
a = -0.14125 
b =  0.0008125
OXY2=OXYl+∆OXYl

3. Step: High order polynomial fit to correct the pressure effect of the oxygen sensor 
a: In upper water column; 0 to 2370 dbar:
∆OXY2 = a+b * PRES
with:
a = -0.04598245614 
b =  2336842105E-005 
and pressure given in decibar.

b: In the deep water column; pressure > 2370 dbar:
∆OXY2 = a+b*PRES+c*PRES(^2)+d*PRES(^3)+e*PRES(^4)+f*PRES(^5)+g*PRES(^6)
with: 
a =  0.01938375746 
b = -0.0001436734808 
c =  7.707321788E-008 
d =  1.241336138E-011 
e = -1.460247804E-014 
f =  3.065354609E-018 
g = -2.023542164E-022 
and pressure given in decibar.

The final corrected CTD oxygen reading is:

OXY(corr) =OXY2+∆OXY2

The correction of the NIOZ CTD oxygen sensor was made for two separated parts 
due to the sensor drift which can be clearly identified in Fig. 2.29. Two 
individual steps of correction were applied for the first part from station 
number 97 to 178:

1. Step: Correction of the oxygen sensors pressure effect
∆OXYl = a + b*log(pressure)
with:
a = 0.5972460117 
b = -005964890171 
and pressure given in decibar.

2. Step: Linear correction of the oxygen sensor drifts
∆OXY2 = a + b * Stationnumber
with:
a = 0.242 
b = -00019

The final corrected CTD oxygen reading for station 97 to 178 is:

OXY(corr) = OXY+ ∆OXYl + ∆OXY2

The following correction was applied for the second part form station number 187 
to 252:

1. Step: Linear correction of the oxygen sensor drifts
∆OXYl = a + b * Stationnumber
with: 
a =  2.975 
b = -0.01625

2. Step: High order polynomial fit to correct the pressure effect of the oxygen 
sensor
∆OXY2 = a+b*PRES+c*PRES(^2)+d*PRES(^3)+e*PRES(^4)+f*PRES(^5)+g*PRES(^6)
with:
a = -0.1744698393 
b =  0.0007819713073 
c = -8.445337449E-007 
d =  3.882443376E-010 
e = -9.007417652E-014 
f =  1.034638749E-017 
g = -4.679330148E-022 
and pressure given in decibar.

The final corrected CTD oxygen reading for station 187 to 252 is:
OXY(corr) = OXY + ∆OXYl + ∆OXY2


Fig. 2.30 shows the remaining oxygen difference between the measured samples and 
the corrected reading from the CTD oxygen sensor. The sensor from the NIOZ CTD 
shows a little higher noise than the AWI CTD oxygen sensor which reflects the 
sensor problems which were already visible in the plot of the uncorrected data.

The standard deviation for the AWI CTD is 0.04 and 0.07 for the NIOZ CTD. From 
there the accuracy for all CTD oxygen is better than ±0.1 ml/l.


Fig. 2.30: Oxygen difference between the measured samples and the reading from 
           the CTD's oxygen sensor after applied corrections versus station 
           number for the AWI and NIOZ system.


The oxygen profiles of the CTD were constantly compared with the results of the 
titration along the expedition. The profiles were roughly corrected by shifting 
them horizontally (adding or subtracting an offset) until they optimally matched 
the titration results by minimal quadratic differences (Fig. 2.31 shows station 
244 as an example). Fig. 2.32 shows the offset between each CTD profile and the 
corresponding titration values against the station number.

The authors of this report wrote also an succinct manual about oxygen sampling 
and measuring. This manual is available under request.


Fig. 2.31: Comparison of the oxygen profile of the CTD sensor of Station 244 
           (black continuous line) and the titration values (stars). To monitor 
           the results (and not as calibration procedure), the CTD profile has 
           been shifted adding an offset until it matched by minimum quadratic 
           differences the titration values (grey dashed line).


Fig. 2.32: Offset between the CTD oxygen profiles and the titration results for 
           the AWI CTD (red) and the NIOZ CTD (black) as a function of the 
           station number. The offset is defined as the amount of oxygen added 
           or subtracted to the profile as to match the titration values by 
           minimum quadratic differences.



3.  GEOTRACES IN THE INTERNATIONAL POLAR YEAR DURING ANT-XXIV/3 EXPEDITION

General objectives
One major aim of international GEOTRACES (http://www.geotraces.org) is:

  "To determine global ocean distributions of selected trace elements and 
  isotopes, including their concentration, chemical speciation, and 
  physical form, and to evaluate the sources, sinks, and internal cycling 
  of these species to characterise more completely the physical, chemical 
  and biological processes regulating their distributions".

The International Polar Year (IPY) is an excellent opportunity to study Trace 
Elements and Isotopes in the Arctic and Antarctic Oceans. An international suite 
of vertical sections in the polar oceans is integrated in the IPY project No. 35
(http://www.ipy.org/development/eoi/proposal-details.php?id=35) entitled:
"International Polar Year GEOTRACES: An international study of the 
biogeochemical cycles of Trace Elements and Isotopes in the Arctic and Southern 
Oceans". In context of this IPY-GEOTRACES, two Polarstern cruises have been 
implemented, in the Arctic Ocean (ARK-XXII/2; 2007) and the current expedition 
in the Antarctic Ocean (ANT-XXIV/3; 2008), respectively.

Organization

The GEOTRACES research of ANT-XXIV/3 pivots around three research teams 
of Royal NIOZ, IFM-GEOMAR and AWI led by Principal Investigators (PI) 
Hein de Baar, Peter Croot and Michiel Rutgers van der Loeff, 
respectively. Moreover there are several participants of other 
institutes CNRS-LEGOS, Stanford University and University of Groningen 
taking part in one or another of these teams.

Data management

All data of Isotopes and Trace Metals will be reported into the 
worldwide database of the GEOTRACES programme. Within the GEOTRACES 
Scientific Steering Committee, Dr. Reiner Schlitzer (AWI) is the SSC-
member responsible for the database, and will be able to correspond 
regularly with the other SSC members Michiel Rutgers van der Loeff 
(AWI) and Hein de Baar (NIOZ) which had organized the ANT-XXIV/3 
GEOTRACES component.



3.1  Trace elements during ANT-XXIV/3 expedition: NIOZ team

     Anne-Carlijn Alderkamp(3), Hein de Baar(1),  (1)NIOZ
     Babette Bontes(2), Loes Gerringa(1),         (2)University of Groningen
     Maarten Klunder(1), Patrick Laan(1),         (3)Stanford University/ 
     Rob Middag(1), Ika Neven(2), Sven Ober(1),      University of Groningen
     Jan van Ooijen(†1), Willem Polman(1), 
     Cornelis van Slooten(2), 
     Charles-Edouard Thuroczy(1)

In GEOTRACES we have defined 6 key trace metals (Tab. 3.1) which, 
together with additional metals Co, Ni, Ag will be investigated in IPY-
GEOTRACES subprojects. The distribution and biological availability of 
Fe (3.1.1) is strongly controlled by its physical-chemical speciation 
(3.1.2) within seawater, where colloids and Fe-organic complexes are 
dominant actors. The external sources of Fe into the oceans are either 
from above (dust) and below (sediments) and will be constrained by Al 
and Mn (3.1.3) for aeolian dust input and sedimentary redox cycling 
sources, respectively. For phytoplankton growth, Cu (3.1.4) at the cell 
wall acts in reductive dissociation of Fe-organic complexes, hence 
facilitates Fe uptake. This may partly explain the nutrient-type 
distribution of Cu in the oceans. The Fe enhances phytoplankton growth, 
which in turn strongly controls the biological pump for uptake of CO2 
from the atmosphere into polar oceans (4.). The increasing CO2 in polar 
ocean waters may affect phytoplankton ecophysiology (3.1.7), with key 
links of metals Fe (3.1.1) in the overall photosynthetic apparatus and Zn 
(3.1.4) in carbonic anhydrase and respectively, where Cd and Co (3.1.4) 
may substitute for Zn in the latter carbonic anhydrase.


Tab. 3.1: The 6 trace metals with high priority in GEOTRACES. Many more 
          trace metals are measured during GEOTRACES, yet these 6 were measured 
          or sampled on all sections. Moreover Co, Ni, Ag of subproject 3.1.4.

Fe Iron       Most important essential micronutrient
Al Aluminium  Tracer of Fe inputs (from mineral dust and elsewhere)
Zn Zinc       Second important micronutrient; co-factor in carbonic
              anhydrase; toxic at high concentrations; environmental 
              pollutant worldwide
Mn Manganese  Tracer of Fe inputs and redox cycling; Fe-Mn in 
              superoxide dismutase
Cd Cadmium    Essential micronutrient; paleoproxy for phosphate in 
              seawater; toxic at high concentrations; environmental 
              pollutant worldwide
Cu Copper     Essential micronutrient (toxic at high concentrations); 
              toxic at high concentrations; environmental pollutant worldwide
Co Cobalt     Essential micronutrient; co-factor vitamin 131 2
Ni Nickel     Essential micronutrient; in urease
Ag Silver     Analog of both Cu and Si; paleoproxy for nutrient silicate;
              environmental pollutant



3.1.1  Distributions, sources, sinks of dissolved Fe in Polar Oceans

       Patrick Laan, Maarten Kiunder 
       NIOZ

Very little data exists on Fe in waters of the Antarctic Ocean. There 
is some data for Fe (or other trace metals) in surface waters of the 
Arctic Ocean, and very little at depths below ca. 1000 metres. Since 
the 1988 European Polarstern Study the role of Fe in ecology of the 
Southern Ocean has been investigated, including the Fe distributions, 
speciation, sources and sinks. Nevertheless in an exhaustive synthesis 
of all then existing ocean Fe data uncertainty remained as to the 
actual, correct, concentration of Fe in ocean waters. Therefore total 
dissolved Fe is a top priority in GEOTRACES. ANT-XXIV/3 aimed for two 
complete sections on distributions of Fe (and other trace metals) in 
the Antarctic Ocean.

Work at sea

Dissolved iron was measured directly on board by Flow Injection 
Analysis (FIA) after De Jong et al. 1998 in a cleanroom container. In a 
continuous FIA system the acidified pH 1.8, filtered (0.2 µm) seawater 
is buffered to pH 4.0. The iron is concentrated on a column which 
contains the column material aminodiacetid acid (IDA). This material 
binds only transition metals and not the interfering salts. After 
washing of the column with ultra pure water (MO) the column is eluted 
with diluted acid. After mixing with luminol, peroxide and ammonium the 
oxidation of Iuminal with peroxide is catalysed by iron and a blue 
light is produced and detected with a photon counter. The amount of 
iron is calculated using a standard calibration line, where a known 
amount of iron is added to low iron containing seawater. Using this 
calibration line a number of counts per nM iron is obtained.

All 23 stations on the prime meridian and corresponding depths have 
been analyzed on board. The values of DFe measured varied from below 50 
pM in the surface waters up to more then 2 nM. The standard deviation 
varied between 0% and 7% (exceptional), but was generally lower than 
4%. The standard deviation of the values is determined of a triplicate 
measurement of the same sample bottle. To correct for contamination 
during the process or in the sample bottle a duplicate sample was taken 
of every station depth. The daily consistency of the system was 
verified using a drift standard. Regularly a certified SAFe standard 
(Johnson et al. 2007) for the long term consistency and absolute 
accuracy was measured.

Next to the 23 stations also the amount of dissolved iron in the 1000 
kDa filtered fraction was measured for 7 casts. The corresponding 02 pm 
filtered fraction of the same casts was also measured. The 1,000 kDa 
filtered fraction generally contained a lower amount of dissolved iron.

Although all ultraclean CTD casts were sampled for the determination of 
dissolved iron on board only the samples from the prime meridian were 
measured. Due to the accident at Neumayer station we were not able to 
measure all the station taken and all the primaire goal was to finish 
the prime meridian.

Preliminary results

The preliminary data shown in Fig. 31, show that the concentrations of 
dissolved iron in South Atlantic Sector of the Southern Ocean are 
comparable to the concentrations found in the North Atlantic Deep 
Waters, 0.6 -0.7 nM. (Martin et al., 1993).

Elevated DFe values were observed around 55°S and are most probably 
related to hydrothermal activity from the area where the Mid Atlantic, 
the Southwest Indian and the America-Antarctic Ridges meet. The lowest 
DFe concentrations were observed in the surface of the most southerly 
located stations. Fig. 3.2 shows a typical profile of the DFe as 
observed in the Southern Ocean.


Fig. 3.1: Distribution of DFe on a section along the Greenwich meridian 
          for
Fig. 3.2: Depth profile of dissolved Iron


References

Johnson et al., 2007. Developing standards for dissolved iron in 
    Seawater. Eos, Vol 88, n. 11.

Martin J.H., Fitzwater, SE., Gordon, R.M., Hunter, C.N., and Tanner, 
    S.J. (1993), Iron, primary production, and carbon- nitrogen flux 
    studies during the JGOFS North Atlantic Bloom Experiment. Deep sea 
    Research II. 40, 115-134.

De Jong, JIM, den Das, J., Bathmann, U., Stoll, M. H.C., Kattner, G., 
    Nolting, R.F., and de Baar, H.J.W. (1998). Dissolved iron at 
    subnanomolar levels in the Southern Ocean as determined by shipboard 
    analysis. Analytica Chimica Acta, 377, 113-124.



3.1.2  Physical and chemical speciation of iron in seawater

       Charles-Edouard Thuroczy and Loes Gerringa 
       NIOZ

Objectives

The distribution and biological availability of Fe is strongly 
controlled by its physicalchemical speciation within seawater, where 
colloids and Fe-organic complexes are dominant factors. In order to 
study the distribution and the biological availability of Fe the 
natural Fe organic complexes over the whole water depth were determined 
in three different size fractions. Special attention was given that 
distinct water masses present were sampled as well.

Samples were collected by an ultraclean sampling system using 24 Go Flo 
bottles fixed on an all-titanium frame and with a Kevlar cable. The 
concentration of iron binding ligands (organic compounds which strongly 
bind Fe) and their binding strength (conditional stability constant) 
are studied in 3 size classes here: unfiltered water, 0.2 µm filtered 
water and smaller than 1,000 KDa ultra-filtrated water.

Methods

General

Under ultraclean conditions the 0.2 µm filtered seawater was ultra-
filtrated using polyethylene hollow-fiber filters as to make an 
operational defined distinction between large colloidal and small 
colloidal Fe including the "truly dissolved" Fe (1,000 KDa nominal 
weight, Stereapore, Mitsubishi-rayon Co. Ltd, Nishioka and al., 2005). 
The dissolved organic iron (0.2 µm filtered) as well as the truly 
dissolved iron (< 1000 KDa) were analysed by Maarten Klunder and 
Patrick Laan using a chemo luminescence method (FIA) with acidified 
samples (pH 1.8). Total iron will be measured 6-12 months after the 
acidification of the unfiltered sample. The natural ligand 
characteristics were determined by doing a complexing ligand titration 
with addition of iron (between 0 and 8 nM of Fe added) in buffered 
seawater (mixed NH3/NH4OH borate buffer, 5 mM). The competing ligand 
'TAC' (2-(2-Thiazolylazo)-pcresol) with a final concentration of 10 µM 
was used and the complex (TAC)2-Fe was measured after equilibration (> 
15 h) by cathodic stripping voltammetry (CSV) (Croot and Johansson, 
2000). The electrical signal recorded with this method (nA) was 
converted as a concentration (nM), then the ligand concentration and 
the binding strength were estimated using the non-linear regression 
of the Langmuir isotherm (Gerringa and al., 1995).

The voltammetric equipment consisted of a µAutolab potentiostat (Type 
I, II and III, Ecochemie, The Netherlands), a mercury drop electrode 
(model VA 663 from Metrohm). All equipment was protected against 
electrical noise by a current filter (Fortress 750, Best Power).

Extra experiment

Instability with time of the unfiltered seawater was observed during 
the ARK-XXII/2 cruise in 2007 and made the estimation of the ligand 
characteristics difficult. This raised the question how long samples 
could be kept before analysis ("expiration") because life (algae, 
bacteria, viruses) modified the equilibrium in the sample.

Three experiments were performed in order to establish the "expiration 
date" of the unfiltered seawater samples. These experiments want to 
explain what causes the perturbations in the samples.

For this, four size fractions were analysed after different conditions 
of conservation (temperature and light). The four fractions were 
unfiltered water, 1 pm filtered water (without the big algae), 02 µm 
filtered water (without the pico-eucaryotes) and 1,000 KDa filtered 
water. With the collaboration of Claire Evans and Erwin Frijling, the 
total chlorophyll fluorescence of the algae was measured by Phyto-PAM 
(Pulse Amplitude Modulation) and followed in time (between 5 and 10 
days), as well as the amount of living small algae (pico-eucaryotes) 
measured by flow-cytometry. Samples for bacteria analyses were also 
taken and will be analysed at NIOZ. The dissolved iron concentration 
was measured by FIA and the ligand concentrations and binding strength 
were measured on board by voltammetry.

Another experiment was performed in order to establish a mass balance 
of the ligands before and after the ultrafiltration. Four classes of 
size were then analyzed, the unfiltered fraction, the 0.2 µm filtered 
fraction the 1,000 KDa ultrafiltered fraction, but also the fraction 
left after the ultrafiltration (size between 0.2 µm and 1,000 KDa).

Sampling statistics

Seven stations were sampled on the Greenwich meridian transect with a 
maximal depth of 4,500 m. A total of 140 samples on 56 depths were 
sampled (28 of unfiltered, 56 of 02 µm filtered and 56 of 1,000 KDa 
ultra-filtered). Among them, 11 depths characterizing the most 
important water-masses were sampled twice and kept frozen for later 
analyses while back at NIOZ (for the study of kinetic exchange between 
the different forms of iron).

Two profiles were sampled in the Weddell Sea for a total of 46 samples 
(8 of unfiltered, 19 of 0.2 µm filtered and 19 of 1000 KDa ultra-
filtered). 8 depths were also sampled twice to characterize important 
water-masses. Two other depths were also taken on a third station to 
start the mass balance experiment.

In the Drake Passage one station was sampled for a total of 30 samples 
(10 depths). A second station was used to continue the masse balance 
experiment.

Preliminary results

Only results of the fraction smaller than 0.2 µm could be calculated at 
the time of this report. The following figures (33, 3.4 and 3.5) show 
the vertical profiles of iron and of the ligands in the fraction 
smaller than 0.2 µm. These 3 profiles are 3 stations along the 
Greenwich meridian. The concentration of the ligand is expressed in 
nanoequivalents of mol Fe (nEq of MFe), meaning sites present at the 
ligand molecules at which Fe can be bound in such a way as described by 
the determined binding strength (conditional stability constant). The 
conditional stability constant ranged from 10(^21.87) to 10(^23.35), and 
a mean value of 10(^22.44).

The excess ligand concentration is calculated by subtracting the 
dissolved Fe concentration from total ligand concentration, resulting 
in the concentration of empty ligand sites (not filled with Fe) of the 
sample. In all samples, except one, the excess ligand concentration was 
larger than zero, implicating that more than 99% of the dissolved Fe 
was bound to the ligands. It is possible that the sample in station 107 
at 2,500 m depth (Fig. 3.5) was contaminated with Fe.

The results of the extra experiments indicate that unfiltered samples 
stored correctly (4°C) can be kept for 1 or 2 days before changes 
occur. However, as soon as the algae die, changes occur in the ligand 
concentration as well as in the binding strength of the ligand.


Fig. 3.3: Station PS 71-101/2, concentration of iron and ligands with
          the depth
Fig. 3.4: Station PS 71-103/1,  concentration of iron and ligands with
          the depth
Fig. 3.5: Station PS 71-107/3, concentration of iron and ligands with
          the depth


References

Croot P.L., Johansson M. (2000). Determination of iron speciation by 
    cathodic stripping voltammetry in seawater using the competing ligand 
    2-(2-Thiazolylazo)-p-cresol (TAC). Electroanalysis. 12, No.8, 565-576.

Nishioka J., Takeda S., de Baar H.J.W., Croot P.L., Boye M., Laan P., 
    Timmermans K.R. (2005). Changes in the concentration of iron in the 
    different size fractions during an iron enrichment experiment in the 
    open Southern Ocean. Marine Chemistry. 95, 51-63.

Gerringa, L.J.A., P.M.J. Herman, T.C.W. Poortvliet (1995). Comparison 
     of the linear Van den Berg/Ruzic transformation and a non-linear fit of 
     the Langmuir isotherm applied to Cu speciation data in the estuarine 
     environment. Marine Chemistry. 48, 131-142.



3.1.3  Dissolved Al and Mn as source tracers for iron

       Rob Middag and Cornelis van Slooten 
       NIOZ

Objectives

For the world oceans, the initial hypothesis of Fe coming from above 
has been challenged by upwelling supply from below where reducing 
marine sediments are the ultimate Fe source. Dissolved Al in surface 
waters is a tracer of aeolian dust input and indeed very high in the 
Mediterranean where dissolved Fe is also high due to dust supply from 
the adjacent Sahara and Egypt arid regions. The dissolved Al and 
dissolved Fe also co-vary on a transect from the Canary Basin to 
Gibraltar. Data of Al is scarce in polar seas, and IPY GEOTRACES aims 
to fill this gap for better assessment of dust input. Elevated 
dissolved Mn and Fe in reducing environments render dissolved Mn a 
source tracer for Fe from below, i.e. from reducing sediments. Our 
combined Mn-Fe data, also with natural radiotracers will quantify the 
Fe from below source.

Work at sea

Dissolved Al and dissolved Mn were measured directly using shipboard 
FIA measurements. In a continuous FIA system, the acidified pH 1.8, 
filtered (0.2 µm) seawater is buffered to pH 5.5 and 85 for Al and Mn, 
respectively. The metals are concentrated on a column which contains 
the column material aminodiacetid acid (IDA). This material binds only 
transition metals and not the interfering salts. After washing of the 
column with ultra pure water (MO) the column is eluted with diluted 
acid.

The Al is determined using lumogallion after Brown and Bruland (2008). 
Lumogallion is a fluorometric agent and reacts with aluminium. The 
change in the fluorescence detected by a fluorometer is used as a 
measure for the dissolved Al concentration.

In order to verify the consistency of the analysis, every day a sample 
was measured from a 25 liter tank that was filled in the beginning of 
the cruise. Also a duplicate sample was taken every cast and this 
sample was analysed with the samples of the next cast to further check 
for inter daily variation. Furthermore, SAFe seawater samples were 
analysed daily and the values are consistent with those found by 
Brown and Bruland (2008).

The Mn is detected using the chemoluminescence method of Doi et al. 
(2004). The oxidation of luminol by hydrogen peroxide produces a blue 
light. This oxidation reaction is catalyzed by manganese and the 
increase in the production of blue light is detected by a photon 
counter and used as a measure for the dissolved Mn concentration.

Also for Mn similar consistency checks as for Al have been performed 
with samples from the 25 liter tank and duplicate samples. Also SAFe 
seawater was analysed which was consistent with the values found 
previously in the lab and by Mendez (pers. com). The daily consistency 
of the system was verified using a so-called drift standard.

Preliminary results

The preliminary data shows that the values in the surface for dissolved 
aluminium are low over the Greenwich meridian (Figs. 3.6 and 3.7). The 
increase of Al with depth as observed in the Arctic and North Atlantic 
oceans is far less profound in the Southern Ocean. Higher deep values 
of up to 6 nM were found closest to the African continent while close 
to the Antarctic continent the deep values where below 2 nM. The 
section over the Greenwich meridian consisted of 22 stations and a 
total of 486 samples were analysed for dissolved Al over the Greenwich 
meridian. Another 8 stations were sampled in the Weddell Sea and 10 
more in the Drake Passage bringing the total number of samples to 915. 
The Weddell Sea bottom water appears to be somewhat enriched in 
dissolved Al and some elevated values were found just under the surface 
going into the Drake Passage.

The Mn values are quite low throughout the water column (Figs. 3.8 and 
3.9), except for areas with suspected hydrothermal input enriching the 
deep waters with Mn. Going from deep to surface the Mn values start to 
increase towards the surface as is generally observed for Mn, but the 
values drop sharply in the last 25 to 50 metres indicating a depleted 
surface layer. The section over the Greenwich meridian consisted of 22 
stations and a total of 496 samples were analysed for dissolved Mn. 
Another 8 stations were sampled in the Weddell Sea and 10 more in the 
Drake Passage bringing the total number of samples to 926. These 
sections showed Mn input from the Peninsula and Antarctic islands.


Fig. 3.6: Distribution of dissolved Al on a section along the Greenwich 
          meridian
Fig. 3.7: DAI profile station 167 Greenwich meridian
Fig. 3.8: Distribution of dissolved Mn on a section along the Greenwich 
          meridian
Fig. 3.9: DMn profile station 167 Greenwich meridian


References

Doi, T., Obata, H., Maruo, M., 2004. Shipboard analysis of picomolar 
    levels of manganese in seawater by chelating resin concentration and 
    chemiluminescence detection. Analytical Bioanalytical Chemistry 378 
    (5), 1288-1293.

Brown, MT., Bruland, K.W., 2008. An improved flow-injection analysis 
    method for the determination of dissolved aluminum in seawater. 
    Limnology and Oceanography Methods 6,87-95.



3.1.4  Involvement of Co, Ni, Cu, Zn, Ag, Cd in biological cycles in 
       Polar Oceans

       Patrick Laan, NIOZ
       not on board: E. Achterberg, NOC

Objectives

The first row of transition metals (Mn, Fe, Co, Ni, Cu, Zn) are 
essential for every living cell, in the sea and on land. Co is co-
factor in vitamin B12, which most phytoplankton cannot synthesize 
hence needs to be provided in ocean waters. Zinc is in carbonic 
anhydrase for CO2 fixation by algae. Substitution of cobalt Co or 
cadmium Cd in carbonic anhydrase may occur under Zn deficiency stress. 
Also a specific Cd-based carbonic anhydrase exists in a certain diatom. 
These enzyme functions may partly explain the co-variance in the oceans 
of Zn with silicate (see 3.1.5), and Cd with phosphate. Also nickel Ni 
co-varies with both phosphate and silicate, and copper Cu resembles 
silicate, albeit less due to deep ocean Cu removal (akin to deep ocean 
Fe removal, see 3.1.2). The second row metal silver (Ag), despite 
having no biological function, also correlates with silicate. The thus 
far small (Cd, Ni, Cu) or very small (Zn, Ag) ocean data sets suggest 
interaction of Zn and Ag with the diatoms-and-Si cycle, and all (Ni, 
Cu, Zn, Ag, Cd) with the general ocean carbon cycle. The parallel 
measurements of nutrients (nitrate, phosphate, silicate) and alkalinity 
allows our study of metal-nutrient co-variances. With regards to the 
trace metals Cd, Cu, Ni and Zn this allows synergy and internal 
consistency with the project of Dr. Peter Croot (lfM-GEOMAR).

Work at sea

At each ultraclean station cast sample bottles of one litre each were 
filled with filtered seawater for measurements afterwards in the home 
laboratory of Co, Ni, Cu, Zn, Cd as well as dissolved Fe. Latter 
dissolved Fe as a duplication hence confirmation/verification of the 
direct shipboard detection. The home laboratory measurement of this 
suite of trace metals will be done by High-Resolution Inductively 
Coupled Plasma Mass Spectrometry (HR-ICP-MS) with preceding in-line 
column preconcentration of the metal elements from seawater. Another 
set of small 60 ml bottles was collected and stored for measurements 
afterwards of dissolved silver Ag in the laboratory of collaborator Dr. 
Eric Achterberg, National Oceanography Centre, Southampton, UK.

Expected results

Within two years we hope to have analysed in all samples the first row 
of transition metals. With these results we hope to get a better 
understanding of the trace metal distributions throughout the world 
oceans and especially in the "High Nutrient Low Chlorophyll" region of 
the Southern Ocean.


3.1.5  Fractionations of the stable isotopes of cadmium

       Patrick Laan, Rob Middag, Cornelis van Slooten, Charles-Edouard 
       Thuroczy, Hein de Baar, NIOZ 
       not on board: Wafa Abouchami (MPI Chemie, Mainz), Mark Rehkamper (DESE, 
       London)

Objectives

Within the oceans the trace metal cadmium (Cd) exhibits a close 
correlation with the nutrient phosphate. This suggests an involvement 
of Cd in the ocean biological cycle. This in turn has been suggested to 
serve as a paleoceanographic indicator of past concentrations of 
phosphate in the oceans. Here the elemental ratio of cadmium versus 
calcium (Cd/Ca ratio) in the calciumcarbonate of microfossils, notably 
foraminifera, would serve as a proxy tracer for paleo-phosphate. One 
implicit assumption of this paleo-application is that the Cd/PO4 
proportions in seawater do not change significantly when the ocean 
changes, for example from a glacial period ocean into an interglacial 
period ocean.

The involvement of Cd in the ocean biological cycle (de Baar et al., 
1994; Loscher et al., 1998) may be due to two different processes. On 
the one hand Cd may have true biological uptake in plankton, and a true 
biological function inside the living cell. Until recently Cd was 
deemed to have no biological functionality. However now there is 
evidence of Cd sometimes serving as substitute for zinc (Zn) in the 
enzyme carbonic anhydrase. Moreover there is another line of evidence 
suggesting a truly Cd-based carbonic anhydrase enzyme in some diatoms. 
On the other hand Cd may become adsorbed by, in principle abiotic, 
chemical processes, on the outside of plankton material. When this 
plankton becomes debris and settles into the deep oceans where it is 
remineralized by bacterial consumption, the Cd may be released again 
and return into seawater solution in the deep sea.

In general a true involvement in biological processes implies 
involvement in a large sequence of many biochemical reactions. Each 
reaction giving rise to slight mass fractionation, heavier isotopes 
tend to be left behind somewhat. The overall suite of many biochemical 
reactions will give rise to a significant, detectable, isotopic 
fractionation. This is well known for isotopes of biological elements 
carbon (C) and nitrogen (N). Similarly a significant isotopic 
fractionation of Cd isotopes in marine biota would cause major 
variation of the Cd isotope signal in the seawater from which the biota 
had derived its Cd. Therefore the Cd isotope ratio in various water 
masses will serve to indicate whether or not Cd is truly involved in 
biochemical processes. Moreover once Cd isotope ratio values can indeed 
be measured accurately in seawater, this will also serve as a tool for 
enhancing our understanding of the use of Cd as a paleo-indicator of 
phosphate.

Work at sea

Samples of seawater were collected both with the ultraclean CTD system 
for vertical profiles and with the clean torpedo and pumpline system 
for underway surface waters. Both type of samples were filtered over 
0.2 micron nominal size cutoff filter cartridges and collected into 
pre-cleaned bottles. Sample volumes ranged from 1 L for deep waters 
(where Cd concentrations are deemed to be high), to 5 L in intermediate 
waters, 10 L in upper water column, and 20 L for water collected from 
35 m depth with the torpedo.

At the Greenwich meridian we obtained four vertical profiles of 8-10 
sampling depths each at stations and hydrocasts PS71-104-2, PS71-113-2, 
PS71-138-2 and PS71-163-1 as well as 25 underway samples of 20 L each 
with the IFISH torpedo. In the Weddell Sea two vertical profiles were 
obtained at stations and hydrocasts PS71-198-2 and PS71-216-4, due to 
sea ice cover it was impossible to sample with the torpedo. In Drake 
Passage one vertical profile was obtained at station and hydrocast 
PS71-249-3 and one underway sample of 20 L with the IFISH torpedo. See 
the corresponding hydrocast sheets of A1. Ultraclean CTD for depths 
etc. of the vertical profile samples, and the Zero & Drake folder H. 
Iron Fish Cd Isotopes for fact sheets of the 26 underway surface 
samples with positions, S, T, and nutrients values.


References

De Baar, H.J.W., Saager, P.M. Nolting, R.F. ' Van der Meer, J. (1994) 
    Cadmium versus Phosphate in the World Ocean. Mar. Chem., 46: 261-281.

Löscher, B.M., J.T.M. de Jong and H.J.W. de Baar (1998) The distribution and 
    preferential biological uptake of cadmium at 6°W in the Southern Ocean. 
    Marine Chemistry, 62, 259286.


3.1.6  Trace metal input by aerosols

       Maarten Klunder, Charles-Edouard Thuroczy and Rob Middag 
       NIOZ 
       not on board: Alex Baker, University of East Anglia

Objectives

The input of airblown dust particles (aerosols) into surface waters is 
known to be a source of trace metals in seawater. In order to be able 
to quantify this source an aerosol collector from Dr Alex Baker 
(University of East Anglia) was placed on top of Polarstern's Peildeck. 
Shipboard collection of the aerosols was done by Maarten Klunder, 
Charles-Edouard Thuroczy and Rob Middag. Dr. Alex Baker will analyse 
the aerosols for trace metals in his laboratory.

There is a close link with 3.1.3 where distributions of Al in surface 
waters are determined as independent tracer for aerosol input.

Work at sea
Every 50 to 72 hours a new filter was placed in the aerosol collector, 
depending on daylight and weather conditions. Unfortunately some 
sampling days were lost due to breaking down of the engine of the 
aerosol collector which had to be replaced. In total 21 filters were 
collected. The filters stayed on Polarstern till Bremerhaven in the 
-20°C freezer room.


3.1.7  Dynalife: Dynamic light conditions and iron limitation

       Anne-Carlijn Alderkamp University of Groningen, Stanford University 
       not on board: Kevin R. Arrigo, Stanford University

Objectives

The DYNALIFE project is funded by the US-IPY programme and focuses on 
the interactions between DYNAmic light conditions and Fe limitation 
experienced by Antarctic phytoplankton. In addition to the availability 
of iron, light plays a major role in defining where and when the 
different phytoplankton taxa bloom. The light climate phytoplankton 
experience can be highly dynamic, as a result of diel cycles, changes 
in cloud cover and wind driven mixing of the upper layer of the ocean. 
These alternations between low and high light require regulation and 
acclimation of light harvesting, photosynthesis, and photoprotective 
pigments in the phytoplankton. In response to low light algae maximize 
their light harvesting capacity and photosynthetic efficiency. Yet, 
high light may cause damage to the photosystems leading to 
photoinhibition and therefore requires synthesis of protective 
pigments. Southern Ocean ecosystem model results indicate taxon-
specific differences in photoinhibition may be a key factor in 
determining the distribution of a taxon. And, indeed, experiments with 
Antarctic phytoplankton in the laboratory have identified taxon-
specific differences in photoacclimation and photoinhibition at 
different light conditions that contribute to explaining the observed 
distribution. In addition, iron (Fe) limitation of the algal 
communities in the Southern Ocean is now well documented, and directly 
affects the quantity and efficiency of the photosystems. Thus, 
Felimitation directly affects photoaccl imation and photoinhibition.

The objective of the ANT-XXIV/3 cruise is to determine 1) if Antarctic 
phytoplankton experience photoinhibition when residing near te surface, 
2) if photoinhibition is related to the depth of the mixed layer, and 
3) the importance of repair of photodamage versus photoprotection.

Work at sea

To assess the ratio of photoprotective and light harvesting pigments, 
at 10 stations on the Greenwich meridian and 5 stations on the Weddell 
Sea transect, samples from the upper 100 m of the water column were 
filtered onto GF/F filters under low vacuum pressure, in-situ 
temperature and low light levels. Filters were snap-frozen in liquid 
nitrogen and stored at -80°C for pigment analysis by HPLC at the 
University of Groningen.

To assess the extent of photoinhibition Antarctic phytoplankton receive 
when residing near the surface, short-term deck incubations were 
carried out at 9 stations on the meridian of Greenwich, 8 stations on 
the Weddell Sea and 5 stations on the Drake Passage transect. The depth 
of the mixed layer was determined based on the CTD profile. Samples 
containing in-situ phytoplankton were collected from surface water and 
the chlorophyll maximum. Subsamples were fixed for microscopic analysis 
of phytoplankton species and samples were filtered and stored at -80°C 
for analysis of photosynthetic and -protective pigments as described above. 
The photosynthetic efficiency of phytoplankton (Fv/Fm) was analyzed with a 
PAM fluorometer. Samples were incubated for 20 mins at incident light 
levels in deck incubators. The effect on the photosynthetic efficiency 
was determined by PAM fluorometer and subsequently, recovery of 
photosynthetic efficiency was measured during incubation at in-situ 
temperatures and low light levels. In parallel experiments the repair 
of photodamage was prevented by addition of the inhibitor lincomycin. 
Lincomycin inhibits transcription of chloroplast encoded proteins, such 
as the Dl protein, which is a crucial component of photosystem II and 
one of the first proteins to become damaged by high light.

Preliminary data

Significant photoinhibition was observed as a decrease in efficiency of 
photosynthesis (Fv/Fm) after incubating in-situ phytoplankton samples 
in deck incubators at incident light levels (see Fig. 3.10 for a typical 
example), both for samples from the surface as well as the chlorophyll 
maximum. Part of the decrease in photosynthetic efficiency was 
reversible during 120 mins of recovery under low light conditions. The 
inhibition of repair by the addition of lincomycin did not affect the 
decrease in photosynthetic efficiency during the in-situ incubation, 
but reduced the recovery in almost all experiments. Experiments 
conducted early in the morning, or at low incident light levels showed 
the least photoinhibition, which was rapidly reversed. Experiments 
conducted at higher light levels showed strong photoinhibition, that 
was not (completely) reversed during 120 mins of recovery. In these 
cases, lincomycin prevented recovery completely, as shown in Fig. 3.10.


Fig. 3.10: A typical example of photosynthetic efficiency (Fv/Fm) 
           dynamics during a deck incubation followed by recovery under low 
           light conditions. Means and standard deviations are shown for 
           triplicate incubations of water collected at 10 m and 50 m depth, 
           without and with (+) the addition of lincomycin, an inhibitor of 
           repair of photosystem II.


Future work

The characteristics of photoinhibition and recovery observed during 
incubation experiments will be related to species composition 
(microscopy), the ratio of photosynthetic and -protective pigments 
(HPLC analysis, University of Groningen), the characteristics of the 
mixed layer and the incident irradiance in the experiments.


3.1.8  Southern Ocean primary productivity in a high-CO2 world

       Babette Bontes(1), Ika Neven(1),         (1)University of Groningen
       Stevenvan Heuven(1), Hans SIagter(1),    (2)NIOZ
       Jan van Ooijen(2)

Objectives

Since the beginning of the Anthropocene, atmospheric CO2 levels have 
risen from 280 ppm to 370 ppm. This is higher than any CO2 
concentration experienced on Earth in at least 400,000 years and a 
further increase up to 750 ppm by the year 2050 becomes increasingly 
inevitable. Along with rising atmospheric CO2 comes a continuing 
invasion of CO2 into the world oceans (particularly in polar areas), 
which is predicted to cause a drop of pH by 03 - 0.4 units. As a result 
only half of the preindustrial carbonate ion concentration [C032] might 
remain (Feely et al. 2004). With the biological pump overriding CO2 
outgassing from upwelling deep waters, the Southern Ocean is an 
important sink for anthropogenic CO2. Thus, making the local 
phytoplankton community an important player within the global climate 
system.

Surface ocean pH and CO2 changes in turn might have large impact on 
representatives of the major bloom forming taxonomic classes: diatoms, 
nanoflagellates, and haptophytes (mainly Phaeocystis antarctica) in the 
Antarctic Ocean proper (>50°S), and coccolithophorids in the sub-
Antarctic region (<50°S) of the Southern Ocean. We are going to study 
the effects of different pCO2 in Southern Ocean seawater on the growth, 
vitality and carbon metabolism of the in-situ algal community.

Work at sea
CO2 manipulation experiments

Five CO2 manipulation experiments were conducted. The first examined 
the influence of CO2 under Fe limited and Fe replete conditions; in the 
following experiments, CO2 was alternated only under Fe replete 
conditions. Seawater inoculums were collected from the chlorophyll 
maximum by the NIOZ ultraclean CTD and incubated in 10 L Polycarbonate 
carboys (Nalgene) at ambient temperature under 50 µEinstein m(^2)s(^-1) 
16h: 8h light: dark cycle in a laboratory container. The following CO2 
scenarios were mimicked in a semi-continuous set-up and monitored for 
10 days

    - 190 ppm (Last Glacial Maximum)
    - 370 ppm (Present)
    - 750 ppm (Future 2050 A.D)

Phytoplankton were daily enumerated and identified using flow 
cytometry, for species smaller than 20 pm, and microscope counts for 
large species. Algal viability and photosystem II (PS II) efficiency 
was measured daily on dark-adapted samples by the PhytoPAM fluorometer. 
In addition, nutrient dynamics have been monitored every day. On TO, T 
5 days, T 7 days and T 10 days samples were collected for Fe, 
determination of particulate organic carbon (POC), dissolved organic 
carbon (DOC) and pigment composition. Dissolved organic carbon (DIC) 
and total alkalinity were monitored every other day throughout the 
experiments with methods described in sections 3.4.1 and 4.1. of this report.

Short-term 14CO2/H14C03 disequilibrium experiments (Elzenga et al. 
2000) were carried out on TO, 1 5 days and 1 10 days of the experiments 
to measure the extent external carbonic anhydrase (eCA), an enzyme 
which catalyses the dehydration of bicarbonate (HC03) to CO2 and vice 
versa in the boundary layer of phytoplanktonic cells, contributes to 
the uptake of inorganic carbon. In this way it was possible to 
distinguish between the inorganic carbon species taken up by cells.

Transect

To estimate the extent of bicarbonate uptake and the role of eCA in 
inorganic carbon uptake of Southern Ocean phytoplankton, short-term 
14CO2/H14C03 disequilibrium experiments were carried out. In total 9 
stations were assessed on the Greenwich meridian transect, 10 on the 
Weddell Sea transect and 6 on the Drake Passage transect.

Preliminary results

Measurements of DIC revealed that it took approximately 2 days of 
continuous aeration to reach the required levels of pCO2 in the 
experimental vessels. Subsequently the pCO2 remained reasonably stable 
during the experiment (data not shown).

Fluorescence parameters, growth (Fig. 3.11), viability and 
photosynthetic efficiency (Fig. 3.12) were not affected by the 
different CO2 or Fe treatments. The dynamics of phosphate, silicate and 
nitrate (Fig. 3.13) suggest that neither Fe addition nor differences in 
CO2 concentration affected the nutrient uptake rates of the algae.

14C disequilibrium experiments revealed that communities cultured under 
190 ppm make extensive use of the bicarbonate pool by eCA-mediated 
conversion to CO2This distinct pattern decreased under present CO2 
conditions and ceased totally under future high CO2 conditions. 
Differences were already visible after the short incubation time of 5 
days (Fig. 3.14). After analysis of pigment composition, POC and 
microscope samples a quantitative approach will be possible.

In consistence with the experimental data, preliminary results of the 
Greenwich meridian and Weddell Sea transect suggest that the majority 
of phytoplankton makes only modest use of the bicarbonate pool under 
present CO2 conditions.

The existence of a Carbon Concentrating Mechanism such as eCA that is 
quickly induced under low CO2 conditions implies that the majority of 
phytoplankton is well adapted to changing CO2 conditions. External CA-
mediated conversion of bicarbonate to CO2 may have been beneficial in 
the past during changes in CO2 concentrations over geological 
timescales as well as during fast occurring CO2 shifts, for example 
during a phytoplankton bloom. However, under future high CO2 scenarios 
this once evolutionary advantageous trait might become redundant.


Fig. 3.11: Phytoplanktonic growth during experiment 1
Fig. 3.12: Photosynthetic efficiency of phytoplankton during experiment 1
Fig. 3.13: Dynamics of nitrate, phosphate and silicate during experiment 1
Fig. 3.14: Differences in bicarbonate utilization by the in-situ 
           phytoplankton community cultured for 5 days under different pCO2 
           conditions (l9Oppm, 38Oppm, 75Oppm)


References

Elzenga, J.T.M., Prins, H.B.A. and Stefels, J. (2000). The role of 
    extracellular carbonic anhydrase activity in inorganic carbon 
    utilization of Phaeocystis globosa (Prymnesiophyceae): a comparison 
    with other marine algae using the Isotopic Disequilibrium Technique. 
    Limnology and Oceanography. 45: 372 - 380.

Feely, R.A., Sabine, C.L., Lee, K., Berelson, W., Kleypas, J., Fabry, 
    V.J. and Millero, F.J. (2004). Impact of anthropogenic CO2 on the 
    CaCO3 system in the oceans. Science. 305: 362-366.



3.1.9  Ultraclean CTD and sampling system

       Sven Ober(1), Willem Polman(1)              (1)NIOZ
       (deceased 2 March 2008), Mihael Stimac(2)   (2)Heli Service
		
This CTD and sampling system was operated by Sven Ober (CTD operator 
and electronics) and Willem Polman (winch operator and overall 
mechanics). Due to the tragic loss of Willem Polman, the kind offer of 
Michael Stimac to continue as winch operator was gratefully accepted. 
This and the much appreciated extra support of the shipboard CTD team 
allowed the system to be operational again from 9 March onwards.

During the cruise a special CTD system was used to sample for trace 
elements and isotopes. This CTD system consists of 3 major modules: a 
winch with a super-aramide CTD cable, a box-shaped titanium CTD frame and a 
clean air container that is designed to hold the CTD frame in order to enable 
subsampling and filtration under clean air conditions. The CTD frame is 
made of pure titanium and was equipped with a Seabird SBE9+ CTD 
underwater unit, a double SBE3/SBE4 temperatureconductivity-sensor set 
each with a separate SBE5 underwater pump, an SBE43 DOsensor, a Chelsea 
MK-111 fluorometer, a Seapoint OBS and a special sampling system. This 
sampling-system consists of a Multivalve hydraulic multiplexer and 24 
GoFlo sampling bottles each with its own hydraulic release unit. (De 
Baar et al, 2007 and Ober et al, 2002). The temperature sensors were 
in-situ calibrated with an SBE35 reference thermometer. Salinity 
samples were analysed using an Guildline Autosal 8400B for the 
calibration of the conductivity sensors (See 211). The pressure sensor, 
mounted inside the SBE9+, was monitored using Electronic Reversing 
Pressure Meters, (Brand SIS, type 6000X). Winkler titrations were 
carried out in order to calibrate the SBE43 DO-sensor.

In total 56 casts were carried out with the Ultraclean CTD system (Type 
Al: 41, type B2: 7, type D: 2, type G: 5, type F: 1) including an 
intercalibration cast with the CTD system operated by AWL This cast 
proved that both systems had a sufficient level of data quality 
enabling interchangeability during the cruise.

Throughout the whole cruise the system worked very reliably, although 
some technical problems occurred. The primary conductivity sensor had 
to be exchanged after station 135, cast 1 for a spare because of 
erratic behavior due to a broken cell and the secondary sensor pair 
showed for still unknown reasons a noisy signal. The DO-sensor showed 
some drift in time and some depth dependency.

As part of the processing of the CTD all available pre-cruise, post-
cruise and in-situ calibration data were used to correct for the sensor 
imperfections. The way how the calibration values are obtained and processed 
are described in detail in chapter 2.1.1 of this report. Overall the data 
quality of the salinity is better than +1- 0002 and for temperature better than 
± 0.001 K. The accuracy of the CTD oxygen is better than ± 01 ml/l.

The hydraulic bottle control system worked perfectly (100%) and the 
GoFlo samplers worked very well (better than 99%). The analysis of 
dissolved Fe and dissolved Al showed very low concentrations in the 
surface water. The concentrations of dissolved Mn were very low at 
depth. These low concentrations proved that the sampling system did not 
contaminate the samples. The status of "Ultraclean" was confirmed 
conclusively.


References

De Baar, H.J.W., K.R. Timmermans, P. Laan, H.H. De Porto, S. Ober, J.J. 
    Blom, M.C. Bakker, J. Schilling, G. Sarthau, M.G. Smit and M. Klunder 
    (2008) Titan: A new facility for ultraclean sampling of trace elements 
    and isotopes in the deep oceans in the international Geotraces program, 
    Marine Chemistry, 111, 4-21.

Ober, S., Groenewegen, R.L., Boekel, H.J., Keijzer, E.J.H., Derksen, 
    J.D.J., Laan, M., 2002. A new way of oceanographic watersampling. Abstract 
    of presentation at Inmartech, 8 October 2002, Yokusuku, Japan.
    http ://www.jamstec.go.jp/jamstec-e/whatsnew/inmartech2002/program.pdf.



3.1.10  Ultraclean sub-sampling and filtrations

        Patrick Laan(1), Maarten Klunder(1),             (1)NIOZ
        Rob Middag(1), Cees van Slooten(1),              (2)IFM-GEOMAR
        Charles-Edouard Thuroczy(1), Oliver Baars(2)

Upon the evacuation of Maarten Klunder from Neumayer station, Oliver 
Baars kindly joined the team during the remaining period of subsampling 
from 9 March onwards to the end of the expedition.

Once the ultraclean frame with 24 GOFLO samplers was placed inside the 
clean laboratory van an extensive programme of sub-sampling and 
filtrations was done, typically lasting 3 - 4 hours.

Unfiltered seawater samples have been collected into various pre-
cleaned bottles for the projects 3.1.8, 3.2.5, 3.3.6 (Barium only), 
34.1, 5.1, as well as by the respective analists themselves for 
projects 25 and 4.1.

Filtrations have been done with a 0.2tm Sartorius Sartobran 300 
cartridge filter for the projects 3.1.1, 3.1.2, 3.1.3, 3.1.4, 3.1.5; 
321, 322, 3.2.3; 3.3.6 (Rare Earths only) and 3.3.7.

Moreover filtrations have been done for project 3.3.7 in another 
approach over a suite of two filter membranes of 5 micron and 0.45 
micron nominal size cutoff respectively, placed in-line such that the 
first 5 micron filter takes out the larger size class marine particles, 
and next the finer 0.45 micron filter removes the smaller size class 
particles. In this manner not only the filtered seawater is collected, 
but also the filters for later analysis of the particles on the 
filters.


3.2  Trace elements during ANT-XXIV/3 expedition: IFM-GEOMAR team

     Peter Croot(1) and Rob SherreII(2)       (1)IfM-GEOMAR
                                              (2)Rutgers University

Background and general objectives

In the High Nutrient Low Chlorophyll waters of the Southern Ocean the 
supply of iron controls primary productivity and thus the cycling of 
other key bio-elements (Co, Ni, Cd and Zn). While recent work has 
focused on the role of iron, it is now clear, mostly through at sea 
incubation experiments and laboratory studies, that other elements may 
also play a role in controlling the species composition of the 
phytoplankton and importantly the rates at which macronutrients are 
consumed by phytoplankton. These changes in rates of uptake are then 
reflected as differences in the nutrient ratios, or metal to nutrient 
ratios, of the phytoplankton themselves. A further complicating factor 
is that the chemical speciation and bioavailability of these bio-
elements may also undergo changes as a function of phytoplankton growth 
fuelled by the supply of iron. Understanding of these processes is then 
critical for investigations into primary productivity of the Southern 
Ocean and the sources and sinks for major nutrients. Unfortunately at 
the present time there have been only a limited number of studies on 
the distribution of these elements in the Southern Ocean, and even less 
studies examining the chemical speciation of these elements. Recent 
studies have also indicated that sub-optimal Zn concentrations may 
greatly influence Si and N uptake rates by phytoplankton while the Co 
containing vitamin B12 may be present in the Southern Ocean at 
potentially limiting concentrations for some diatom species however for 
both elements direct evidence is still missing. Thus presently we 
urgently require a comprehensive study encompassing the chemical 
speciation and distribution of the already identified key bio-elements 
(Co, Ni, Cd and Zn) over a range of different Fe and macronutrient 
conditions. Overall such a study will not only improve our 
understanding of trace metal biogeochemical cycling in the Southern 
Ocean but also greatly increase our understanding as a whole of 
nutrient biogeochemistry in this key climatic region.

As part of the GEOTRACES contribution to ANT-XXIV/3 the lfM-GEOMAR 
Aqueous Trace Oxidant and Metal Speciation Laboratory (ATOMSLab) has 3 
main research areas funded by the DFG:

1. Does Fe control the biogeochemical cycling, speciation and 
   distribution of Cd, Zn, Ni and Co in the Southern Ocean?
2. Development of a budgetary scheme for Cd, Zn, Ni and Co in the 
   Southern Ocean, including both concentrations of various inorganic 
   and organic pools, size ranges and the fluxes between them.
3. What controls trace metal solubility (Fe, Al and Ti) in the ocean?

The overall aim of this work is to combine the results of the 
objectives listed above into a comprehensive model of the key processes 
affecting the biogeochemistry of the Cd, Zn, Co, Ni and Ti in the 
Southern Ocean.



3.2.1  Cadmium, cobalt, nickel and zinc speciation in the Southern Ocean

       Oliver Baars and Peter Croot
       IfM-GEOMAR

Objectives

Our main objective during ANT-XXIV/3 was to examine the speciation and 
biogeochemistry of other bio-relevant elements (Cd, Co, Ni and Zn) in 
the iron limited Southern Ocean. While Fe is the primary control for 
phytoplankton productivity in this region, the elements we are 
investigating have also been identified as being important for 
structuring the phytoplankton community and the macronutrient drawdown 
during bloom situations. The interplay between the Fe biogeochemical 
cycle and the physical oceanography of the region with the elements we 
are studying is important for understanding their global cycling. By 
comparison of the chemistries and distributions of Cd, Zn, Co and Ni 
this IPY GEOTRACES study is aiming to improve our knowledge of the 
processes effecting trace metal distributions in the ocean with 
emphasis on the iron limited Southern Ocean.

Introduction

Zn Biogeochemistry - zinc is an element that is required for many 
enzymatic processes and from a marine prospective chief amongst these 
are its role in carbonic anhydrase (Lane and Morel, 2000b) and in zinc 
finger proteins for DNA transcription (Armbrust et al., 2004). Vertical 
profiles of Zn show a strong nutrient like profile (Bruland et al., 
1979; Nolting and De Baar, 1994), with strong similarity to silicate. 
In surface waters Zn is present as weak organic complexes (Bruland, 
1989; Ellwood, 2004; Ellwood and van den Berg, 2000) that lower the 
free zinc concentrations to sub pM levels which based on laboratory 
studies could be potentially limiting for phytoplankton (Brand et al., 
1983; Buitenhuis et al., 2003; Shaked et al., 2006; Sunda and Huntsman, 
1992; Sunda and Huntsman, 1995; Sunda and Huntsman, 2005). However 
deckboard incubation experiments in HNLC regions (Coale, 1991; Coale et 
al., 2003; Crawford et al., 2003) have yet to clearly show any strong 
effect on productivity but have shown differences in N and Si 
assimilation rates (Franck et al., 2003).

There have been a few published studies on Zn distributions in the 
Southern Ocean; Ross Sea (Fitzwater et al., 2000), Drakes Passage and 
Gerlache Strait (Martin et al., 1990) and in the Weddell Sea (Nolting 
and De Baar, 1994; Westerlund and Ohman, 1991). There have been no 
studies of Zn speciation reported yet from Southern Ocean waters.

Cd Biogeochemistry - It is yet to be demonstrated that cadmium is an 
essential element for phytoplankton growth and normally it is toxic at 
levels just above ambient seawater (Brand et al., 1986). However 
recently it has been shown that there is a cadmium containing isoform, 
found in some marine diatoms, of the usual zinc containing enzyme 
carbonic anhydrase (Lane and Morel, 2000a; Lane et al., 2005). This 
apparent biological utilization of Cd (Lee and Morel, 1995; Lee et al., 
1995; Price and Morel, 1990) may explain why this element has a strong 
nutrient like profile in seawater with strongest similarity to phosphate. 
The Cd-phosphate relationship in the global ocean has been studied 
extensively particularly with regard to the Southern Ocean (Frew and 
Hunter, 1992; Löscher et al., 1998; Nolting and De Baar, 1994). The 
true nature of the relationship between Cd and phosphate in the 
Southern Ocean is an important area of study as Cd:Ca ratios in forams 
are commonly used as a paleotracer for P043 (Boyle, 1988; Boyle et al., 
1995).

Iron and Zn bioavailabilty along with CO2 concentrations may influence 
the Cd:P ratio in phytoplankton (Cullen et al., 2003; Cullen et al., 
1999; Cullen and Sherrell, 2005). During the Southern Ocean iron 
enrichment experiments SOIREE (Frew et al., 2001) and EIFeX (Croot in 
prep) there was a considerable conversion of dissolved Cd into 
particulate forms with an apparently high Cd:P ratio, while Zn remained 
mostly in the dissolved phase. This phenomena is currently difficult to 
explain though it may be due to differences in the bioavailabilty of Cd 
compared to Zn, due to weak Cd organic complexation (Bruland, 1992; 
Ellwood, 2004).

There have been no published studies to data of Cd speciation in the 
main Southern Ocean water masses, with studies limited to the coastal 
Ross Sea (Biesuz et al., 2006; Capodaglio et al., 1991; Capodaglio et 
al., 2002) and the subantarctic waters close to New Zealand (Ellwood, 
2004). None of the studies published so far have included the important 
effects of Fe limitation on the Cd speciation.

Co Biogeochemistry - Cobalt is present in seawater at low pM 
concentrations (Jickells and Burton, 1988) and shows depletion in 
surface waters with typically a maximum in intermediate waters. Recent 
work has shown that Co can replace Zn in carbonic anhydrase (Lane and 
Morel, 2000b; Price and Morel, 1990; Yee and Morel, 1996) and that this 
Co-Zn inter-replacement may determine the dominance of either diatoms 
or coccolithophorids (Sunda and Huntsman, 1995), though other studies 
have shown that not all phytoplankton can utilise Co instead of Zn 
(Timmermans et al., 2001). Co is also the central metal atom in several 
key vitamins such as Bi 2, but not all phytoplankton apparently require 
B12 (Swift, 1981). In surface seawater Co(l1) is believed to be 
strongly organically complexed (Ellwood and Berg, 2001; Ellwood et al., 
2005; Saito and Moffett, 2001; Zhang et al., 1990) though a recent 
study suggested that some of this apparently complexed Co(II) may be 
inert Co(III) (van Leeuwen et al., 2005) based on the expected 
dissociation kinetics for Co(II) complexes.

Only one speciation study has been carried out in the vicinity of the 
Antarctic Polar Front (APF) on samples obtained during the Polarstern 
cruise ANT-XVI/3 (Ellwood et al., 2005). In this study Co speciation 
was found to be dominated by inorganic complexes north of the APF, 
while to the south organic complexation was more important, giving rise 
to a large gradient in the free Co concentration in the southern 
surface waters. How this change in Co bioavailabilty may affect 
phytoplankton productivity or community structure was not immediately 
clear though the authors noted that south of the APF the system was 
dominated by diatoms who may have a lower Co requirement than other 
phytoplankton species.

There are few measurements of Co from the Southern Ocean: low levels 
for Co (2040 pM) in the Drake Passage (Martin et al., 1990) with 
similarly low levels (20-40 pM) in the adjacent Weddell Sea (Westerlund 
and Öhman, 1991) and in the Ross Sea (Fitzwater et al., 2000) though a 
more recent study found elevated levels close to the Antarctic 
Peninsula and Deception Island in the Weddell Sea (Sanudo-Wilhelmy et 
al., 2002).

Ni Biogeochemistry - nickel is a required element for the enzyme 
urease, which phytoplankton use to break down urea into ammonia. 
Laboratory studies have shown that Ni deficiency can affect N uptake in 
the form of urea (Price and Morel, 1991). Ni also has a nutrient like 
vertical distribution in the ocean and studies (Donat and Bruland, 
1988; Donat et al., 1994; van den Berg and Nimmo, 1987) have indicated 
it to be weakly organically complexed with up to 20 % in some 
unreactive form (Wen et al., 2006). The kinetics of Ni(II) water loss 
are slow (Hudson and Morel, 1993; Morel et al., 1991) and so 
equilibrium with organic complexes can take many hours to come to 
completion, much longer than the duration of many of the published 
experiments leaving the possibility that the "unreactive" Ni is only 
very slowly exchangeable but not necessarily inert.

There are no published reports on Ni speciation from the Southern Ocean 
and only a handful of studies on its distribution; high levels for Ni 
(4-8 nM) in the Ross Sea (Fitzwater et al., 2000) with similar levels 
in the Weddell Sea (Nolting and De Baar, 1994; Westerlund and Öhman, 
1991).

Work at sea

Water Sampling

In the present work we obtained vertical profiles for these elements 
along the transects in the different regions of the Southern Ocean 
surveyed during ANT-XXIV/3 as part of the IPY GEOTRACES ZERO and DRAKE 
research programme (Fig. 3.15). Depth resolved sampling was performed 
using water collected the NIOZ ultraclean (Al cast) winch.

Trace metal sampling for zinc and cadmium speciation

Samples for zinc (Bruland, 1989) and cadmium (Bruland, 1992) speciation 
were measured at sea in the lfM-GEOMAR Class 100 Clean room container 
using anodic stripping voltammetry (ASV) with a mercury film electrode 
plated on a rotating disk electrode (MFE-RDE). Pseudo polarograms were 
also made from selected stations to examine the Zn and Cd speciation 
further.

Trace metal sampling for total zinc, cadmium, nickel and cobalt

Samples were collected for total dissolved concentration and acidified 
on board for later analysis in Kiel using standard methods for trace 
metals.

Speciation sampling for nickel and cobalt

Samples were collected for dissolved speciation analysis of Ni and Co 
for later in Kiel. Samples were immediately frozen and will be thawed 
only immediately prior to analysis. Laboratory work will focus on kinetic 
aspects of the speciation of these elements at the ambient temperatures 
found in Southern Ocean waters. These measurements were not made at sea due 
to the slow kinetics of these two metals which then requires several days 
of experimental time to make the required measurements.

Preliminary results

During ANT-XXIV/3 we sampled 15 stations at sea for Cd and Zn 
speciation and an equal number for total dissolved metal concentrations 
(Cd, Co, Cu, Fe, Ni, Zn) which will be analysed later in the laboratory 
in Kiel. Samples from 6 stations were also frozen for later analysis 
for Ni and Co speciation. At all stations we observed strong gradients 
in electroactive (labile) Zn and Cd, by which the labile metal 
concentration increased with depth (Fig. 3.16). It also appeared that 
Cd and Zn ligands were present mostly in the surface waters and were 
not so abundant at depth with Cd ligands more important in controlling 
the speciation. Pseudopolarography also confirmed this interpretation 
as for zinc only a single inorganic wave was observed while for Cd two 
distinct waves could be seen suggesting the presence of a reducible 
organic species in the seawater. Further laboratory work should help to 
confirm these original findings. Later work will also involve examining 
the metal :nutrient ratios found in the different water masses during 
ANT-XXIV/3.


Acknowledgments

The authors would like to show their deep thanks and appreciation to 
the crew of the Polarstern, for all their efforts in helping us 
throughout ANT-XXIV/3. Thanks to the winch operating and tapping crew 
of the Ultraclean Al cast who provided all the samples for this study - 
in particular Michael Stimac for taking on a second job at short 
notice. Thanks also to the Chief Scientist, Dr Eberhard Fahrbach and to 
the AWI Logisitics Department for making this cruise possible. Funding 
for participation in this cruise was provided by the DFG (CR145/10) and 
lfM-GEOMAR.


Fig. 3.15: Location of the stations during ANT-XXIV/3 where measurements 
           were made for Cd and Zn speciation. (left) Greenwich meridian, 
           (centre) Weddell Sea and (right) in Drake Passages.
Fig. 3.16: Cd and Zn vertical profiles from the Drake Passage (Station 230)


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3.2.2  Copper speciation in the Southern Ocean: Implications for reactions 
       with superoxide

       Maija Heller and Peter Croot
       IfM-GEOMAR

Objectives

Our primary objective during ANT-XXIV/3 was to examine the chemical 
speciation of copper in the water column of the Southern Ocean and to 
determine whether Cu speciation played a significant role in superoxide 
reactivity. Superoxide is difficult to measure in the ocean because it 
is extremely reactive, particularly with trace metals, and has a short 
half-life. It is however important in metal cycling as it can shuffle 
metals between different redox states with differing biogeochemical 
properties. This is most evident in the case of Cu and Fe where the 
oxidized forms are thermodynamically favored in seawater but are less 
soluble and less reactive than the reduced forms - thus Fe(II) is more 
bioavailable and soluble than Fe(lII). Amongst the biogeochemically 
important trace metals Cu has the fastest kinetic reactivity and is 
thus the main candidate for controlling superoxide reactivity in 
seawater.

Introduction

Importance of copper to oceanic productivity

Copper is an important component of respiratory proteins and oxidases 
(Baron et al., 1995) and as such is a required element for 
phytoplankton. However even at the low level of free copper (Cu2 ) 
concentrations found in the environment (pM to nM), cell
division rates of phytoplankton in culture have been shown to be 
dramatically reduced, particularly for cyanobacteria (Brand et al., 
1986). Elevated free Cu2 in phytoplankton cells can decrease 
photosynthetic rates (Baron et al., 1995), competitively inhibit the 
uptake of other essential metals such as Mn (Sunda et al., 1981; Sunda 
and Huntsman, 1983; Sunda and Huntsman, 1998) and disrupt enzyme 
function through binding to thiol groups(-SH) or from reactions with 
oxygen species to from the damaging hydroxyl radical (Stauber and 
Florence, 1987).

Copper speciation in seawater

Dissolved copper in seawater has been found to be efficiently complexed 
by strong organic ligands, of unknown functionality, but believed to be 
biologically produced (Coale and Bruland, 1988; Moffett et al., 1990; 
van den Berg, 1984). This organic complexation of Cu greatly reduces 
the free copper concentration to below 1 pM in most open ocean waters 
and unpolluted coastal waters (Moffett, 1995; Moffett et al., 1997), a 
level at which most phytoplankton are not Cu stressed (Brand et al., 
1986).

Copper redox speciation

In oxygenated seawater the thermodynamically favoured redox state of Cu is 
Cu(ll), however there are several important redox reactions involving Cu(II) 
that could see cycling between Cu(l) and Cu(II) with significant concentrations 
of Cu(l) present in surface waters (Moffett and Zika, 1988). Most notably Cu(l) 
could be produced by processes including:

  (i) Photochemical reduction of Cu organic complexes (Ferraudi and
      Muralidharan, 1981; Wu et al., 2000).
 (ii) Reduction of Cu (11) by H202 (Moffett and Zika, 1987; Moffett and Zika,  
      1988).
(iii) Biologically mediated reduction of Cu(II) to Cu(l) (Hassett and Kosman, 
      1995; Jones et al., 1987; Jones et al., 1985).

There have been several studies into the oxidation of Cu(l) in seawater (Moffett 
and Zika, 1987; Sharma and Millero, 1988a; Sharma and Millero, 1988b; Sharma and 
Millero, 1989) and in general Cu(l) oxidation in the open ocean is controlled 
through oxidation by 02 as the reaction with H202 is significantly slower under 
typical open ocean conditions.

A generalised mechanism for the oxidation of Cu(I) has been proposed:

        Cu(^+) + O(2) → Cu(^2+) + O(2)(^-)          slow
    Cu(^+) + O(2)(^-) → Cu(^2+) + H(2)O(2)          fast
    Cu(^+) + H(2)O(2) → Cu(^2+) + OH˙ + OH(^-)      slow
         Cu(^+) + OH˙ → Cu(^2+) + OH(^-)            fast
  

For the reduction of Cu(II) by H(2)O(2) the following mechanism has also been proposed:

           H(2)O(2) ↔ H(^+) + HO(2)(^-)             fast
Cu(^2+) + HO(2)(^-) → Cu(^+) + HO(2)                slow
              HO(2) → H(^+) + O(2)(^-)              fast
 Cu(^2+) + O(2)(^-) → Cu(^+) + O(2)                 fast

The Cu(II) reduction rate increases in the presence of strong Cu(I) 
binding ligands. At low concentrations of Cu, the 02 formed may react 
via different pathways, notably that of reactions with Fe(II/III) and 
CDOM (Goldstone and Voelker, 2000; Voelker et al., 2000).

Superoxide

Superoxide is produced in seawater by predominantly photochemical 
pathways, though biological production may also be important. Model 
studies suggest that superoxide would be found in seawater at sub nM 
levels due to its rapid reactions with metals (Cu, Fe) and organic 
matter. However at present there are no direct measurements of 
superoxide in seawater published to confirm this and initial reports 
suggest steady state superoxide levels may be in the tens of nMs in 
sunlit open ocean seawater. The half-life of superoxide is relatively 
short (Millero, 1987) due to a combination of the dismutation reaction 
to form peroxide and reactions with metals such as Cu and Fe. In the 
present work we examined the influence of Cu speciation on superoxide 
half-lifes in seawater as a tool to probe metal redox reactivity in 
seawater.

Water sampling

In the present work we obtained vertical profiles for total Cu along 
the transects in the different regions of the Southern Ocean surveyed 
during ANT-XXIVI3 as part of the IPY GEOTRACES ZERO and DRAKE research 
programme. Depth resolved sampling was performed using water collected 
the NIOZ Ultraclean (Al cast) winch. Speciation measurements were only 
performed in the Weddell Sea and in the Drake Passage (Fig. 3.17).

Copper speciation determination

Copper speciation measurements were made using the ligand 
Salicylaldoxime (SA) with the voltametric method of Cam pos and van den 
Berg (1994). For each station 6 samples from throughout the water 
column were analysed using two detection windows (1 µM and 2 µM SA). 
The data was analysed using a non-linear optimization of a Langmuir 
isotherm (Gerringa et al., 1995).

Superoxide determination using MCLA

In order to determine superoxide at nM concentrations in seawater we 
employed the reagent MCLA ([2-methyl-6-(4-methoxyphenyl)-3,7-
dihydroimidazo[1, 2-a]pyrazin-3-one, HCl]) which is a commonly used 
chemiluminescent technique for the determination of superoxide in 
aqueous solutions. A FIA (Waterville Analytical Maine, USA) system was 
used to follow the reaction of the MCLA with an addition of an aliquot 
of superoxide to seawater samples from different depths, which had been 
amended with either DTPA (to observe only the superoxide dismutation 
reaction), Fe or Cu (both added at nM levels).

Preliminary results

Speciation measurements for Cu were made at 8 stations during ANT-
XXIV/3. In general we found stronger complexation in surface waters 
than in deeper waters. This relationship was also reflected in the 
superoxide reactivity experiments where deep samples had reduced 
superoxide lifetimes and this was further reduced upon addition of Cu 
(Fig. 3.18) and to a lesser extent Fe. Surface water samples had an 
excess of metal complexing ligands and no change in superoxide 
reactivity was seen for the metal additions. The complete data set will 
be analysed once the samples for Total Cu are analysed in the 
laboratory in Kiel.

Acknowledgements

The authors would like to show their deep thanks and appreciation to 
the crew of the Polarstern, for all their efforts in helping us 
throughout ANT-XXIV/3. Thanks also to the Chief Scientist, Dr Eberhard 
Fahrbach and to the AWI Logistics Department for making this cruise 
possible. Funding for participation in this cruise was provided by the 
DFG (CR145/15) and lfM-GEOMAR.


Fig. 3.17: Map of the station locations at which samples were analysed for 
           Cu speciation and reactivity with superoxide
Fig. 3.18: Depth profiles of superoxide kinetics in seawater. (left) 1st 
           order rate constants for the destruction of superoxide in seawater 
           amended with Cu. (right) 1st order rate constants for the
           destruction of superoxide in seawater amended with Fe.


References

Baron, M., Arellano, J.B. and Gorge, J.L., 1995. Copper and photosystem 
    II: A controversial relationship. Physiologia Plantarum, 94: 174-180.
Brand, L.E., Sunda, W.G. and Guillard, R.R.L., 1986. Reduction of 
    Marine Phytoplankton Reproduction Rates by Copper and Cadmium. Journal 
    of Experimental Marine Biology and Ecology, 96: 225-250.
Campos, M.L.A.M. and van den Berg, C.M.G., 1994. Determination of 
    copper complexation in sea water by cathodic stripping voltammetry and 
    ligand competition with salicylaldoxime. Analytica Chimica Acta, 284: 
    481-496.
Coale, K.H. and Bruland, K.W., 1988. Copper complexation in the 
    northeast Pacific. Limnology and Oceanography, 33: 1084-1101.
Ferraudi, G. and Muralidharan, 5., 1981. Photochemical properties of 
    copper complexes. Coordination Chemistry Reviews, 36: 45-88.
Gerringa, L.J.A., Herman, P.M.J. and Poortvliet, T.C.W., 1995. 
    Comparison of the linear van den Berg/Ruzic transformation and a non-
    linear fit of the Langmuir isotherm applied to Cu speciation data in 
    the estuarine environment. Marine Chemistry, 48: 131-142.
Goldstone, J.V. and Voelker, B.M., 2000. Chemistry of Superoxide 
    Radical in Seawater: CDOM Associated Sink of Superoxide in Coastal 
    Waters. Environmental Science and Technology, 34:1043-1048.
Hassett, R. and Kosman, D.J., 1995. Evidence for Cu(II) Reduction as a 
    Component of Copper Uptake by Saccharomyces cerevisiae. The Journal of 
    Biological Chemistry, 270: 128-134.
Jones, G.J., Palenik, B.P. and Morel, F.M.M., 1987. Trace Metal 
    Reduction by Phytoplankton: the role plasmalemma redox enzymes. Journal 
    of Phycology, 23: 237-244.
Jones, G.J., Waite, T.D. and Smith, J.D., 1985. Light-Dependent 
    Reduction of Copper(II) and its effect on Cell-Mediated, Thiol-
    Dependent Superoxide Production. Biochemical and Biophysical Research 
    Communications, 128:1031-1036.
Millero, F.J., 1987. Estimate of the life time of superoxide in 
    seawater. Geochimica et Cosmochimica Acta, 51: 351-353.
Moffett, J.W., 1995. Temporal and Spatial Variability of Copper 
    Complexation by Strong Chelators in the Sargasso Sea. Deep Sea 
    Research, 42: 1273-1295.
Moffett, J.W., Brand, L.E., Croot, P.L. and Barbeau, K.A., 1997. Cu 
    speciation and cyanobacterial distribution in harbors subject to 
    anthroprogenic Cu inputs. Limnology and Oceanography, 42: 789-799.
Moffett, J.W. and Zika, R.G., 1987. Reaction Kinetics of Hydrogen 
    Peroxide with Copper and Iron in Seawater. Environmental Science and 
    Technology, 21: 804-810.
Moffett, J.W. and Zika, R.G., 1988. Measurement of copper(I) in surface 
    waters of the subtropical Atlantic and Gulf of Mexico. Geochimica et 
    Cosmochimcia Acta, 52: 18491857.
Moffett, J.W., Zika, R.G. and Brand, L.E., 1990. Distribution and 
    potential sources and sinks of copper chelators in the Sargasso Sea. 
    Deep-Sea Research, 37: 27-36.
Sharma, V.K. and Millero, F.J., 1988a. Effect of Ionic Interactions on 
    the rates of Oxidation of Copper(l) with 02 in Natural waters. Marine 
    Chemistry, 25: 141-161.
Sharma, V.K. and Millero, F.J., 1988b. Oxidation of Copper(l) in 
    Seawater. Environmental Science & Technology, 22: 768-771.
Sharma, V.K. and Millero, F.J., 1989. The oxidation of Cu(l) with H202 
    in natural waters. Geochimica et Cosmochimica Acta, 53: 2269-2276.
Stauber, J.L. and Florence, TM., 1987. Mechanism of toxicity of ionic 
    copper and copper complexes to algae. Marine Biology, 94: 511-519.
Sunda, W.G., Barber, R.T. and Huntsman, S.A., 1981. Phytoplankton 
    growth in nutrient rich seawater: importance of copper-manganese 
    cellular interactions. Journal of Marine Research, 39: 567-586.
Sunda, W.G. and Huntsman, S.A., 1983. Effect of competitive 
    interactions between manganese and copper on cellular manganese and 
    growth in estuarine and oceanic species of the diatom Thalassiosira. 
    Limnology and Oceanography, 28: 924-934.
Sunda, W.G. and Huntsman, S.A., 1998. Interactive effects of external 
    manganese, the toxic metals copper and zinc, and light in controlling 
    cellular manganese and growth in a coastal diatom. Limnology and 
    Oceanography, 43:1467-1475.
van den Berg, C.M.G., 1984. Determination of the complexing capacity 
    and conditional stability constants of complexes of Cu(II) with natural 
    organic ligands in seawater by cathodic stripping voltammetry of 
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Voelker, B.M., Sedlak, D.L. and Zafiriou, O.C., 2000. Chemistry of 
    Superoxide Radical in Seawater: Reactions with Organic Cu Complexes. 
    Environmental Science and Technology, 34: 1036-1042.
Wu, C.-H., Sun, L. and Faust, B.C., 2000. Photochemical Formation of 
    Copper(I) from Copper(I 1)-Dicarboxylate Complexes: Effects of Outer-
    Sphere versus Inner -Sphere Coordination and of Quenching by Malonate. 
    Journal of Physical Chemistry A, 104: 49894996.



3.2.3  Iron solubility in the Southern Ocean

       Maija Heller and Peter Croot
       IfM-GEOMAR

Objectives

In collaboration with the group of Hein de Baar from NIOZ we examined 
the solubility of iron in water samples from the Southern Ocean. This 
study seeks to determine the processes (complexation, scavenging, redox 
state) that contribute to the distribution of iron in deep waters and 
in the long term transport of iron through the deep ocean. The main 
goal of this work is to determine what controls the solubility of 
dissolved iron in deep waters.

Introduction

Iron is poorly soluble in seawater and careful laboratory measurements 
of inorganic iron solubility (cFes) by Byrne et al. (2005), Kuma et al. 
(1996) and a Fe solubility model of Liu and Millero (1999; 2002) 
suggest that cFes depends on salinity, temperature, pH, with higher 
concentrations of soluble Fe possible at lower temperatures, lower pHs, 
and higher salinities. Fe solubility in both UV irradiated and 
artificial seawater (i.e. seawater containing no dissolved organic 
matter (DOM)), at 0.01 nM between pH 7.5 and 9, has been shown to be 
lower than in untreated seawater (cFes = 0.5 nM) (Liu and Millero, 
2002). This difference can be explained by the existence of natural 
organic ligands (Kuma et al., 1996; Liu and Millero, 2002) which 
enhance the Fe solubility in seawater by organic complexation of the 
trace metal.

More recently iron solubility in deep waters has been found to be 
linearly correlated to the concentrations of macronutrients (e.g., NOR) 
(Kuma, 2002; Tani et al., 2003) possibly due to the release of organic 
ligands during the microbial decomposition of sinking particulate 
organic matter (POM). The regeneration of fluorescent humic substances 
has been observed during organic matter decomposition (and consistent 
with the correlation of nutrients and apparent oxygen utilization 
(AOU)) in the water column (Hayase and Shinozuka, 1995; Hayase et al., 
1988). Some humic substances, such as humic acid, can function as Fe 
binding ligands, increasing Fe solubility at pH 8 by organic 
complexation. Alternatively, Fe binding ligands are released by 
bacteria (Haygood et al., 1993; Martinez et al., 2000; McCormack et 
al., 2003), and could be associated with the growth of the population 
of heterotrophic bacteria decomposing the organic matter. In the 
present work we undertook to examine Fe solubility in deep waters from 
the Southern Ocean for the first time to see if the same apparent 
processes were occurring there as in the North Pacific (Studies of Kuma 
et al., 2002). This work also follows up previous work conducted during 
ANT-XXIII/9 which focused solely on surface waters.

Work at sea

Sampling of subsurface seawater

Seawater samples were obtained throughout the water column using the 
NIOZ ultraclean rosette during ANT-XXIV/3 (Fig. 3.19). The seawater was 
filtered through 0.2 pm membrane filters (Sartorius) under nitrogen 
overpressure (0.2 - 0.3 bar) into 125 mL acid cleaned LDPE bottles 
(Kartell). All sample handling was performed under Class 100 Clean room 
conditions. The samples were frozen at -20°C and transported back with 
Polarstern to Germany for later analysis in the laboratory in Kiel.

Sample treatment

Fe solubility measurements will be performed on thawed aliquots of the 
previously frozen samples using the radioisotope 55 Fe (Hartmann 
Analytics, Braunschweig, Germany). The experimental setup (described 
below) is adapted from Kuma et al. (2002) and is briefly described: An 
addition of 20 nM 55 Fe (to = Oh; pH 7.9) is made to each sample, and a 
small subsample (roughly 9 mL) is filtered through a 0.02 pm Anotop 
syringe filter (Whatman) previously flushed and rinsed with MO water. 
The first 6 - 7 mL of the filtrate is discarded in order to avoid dead 
volume artifacts. The next 1 - 2 mL of filtrate is placed in a 60 mL 
acid cleaned Teflon bottle and acidified with OD-HCI, to keep the Fe 
from adsorbing to the bottle walls (Fischer et al., 2007).

Duplicates of unfiltered and 002 pm filtered samples (400 pL) are 
transferred into 6 mL counting vials to which 4.5 mL of scintillation 
fluid (Lumagel Plus(r)) are then added. The same procedure is repeated 
for subsamples taken after 3, 6, 24, 48 and 72h. After filtration and 
cocktail addition, vials are capped and placed in a liquid 
scintillation counter (Packard, Tri-Carb 2900TR) where each sample is 
counted for 30 minutes. Counts per minute are then converted to soluble 
Fe concentrations, taking into account the activity of the added 
isotope solution and the dissolved Fe concentration of each sample.

Preliminary results

There are no results at present as the samples still need to be 
analysed in the laboratory in Kiel. We anticipate however that the 
results will be complementary to data recently obtained during ANT-
XXIIII9 in the Weddell Sea and Kerguelen Plateau. Using this approach 
we will obtain information about iron solubility in this region and 
data on the kinetics of Fe exchange between soluble and particulate 
forms. This study is a comparison study with work performed within the 
BMBF project SOPRAN (D-SOLAS) which examines iron cycling in the 
surface ocean under the Saharan dust plume.

Acknowledgements

The authors would like to show their deep thanks and appreciation to 
the officers and crew of Polarstern, for all their efforts in helping 
us throughout the duration of ANTXXIV/3. Thanks also to the Chief 
Scientist, Dr Eberhard Fahrbach and to the AWI for making this cruise 
possible. Special thanks to our GEOTRACES colleagues from the 
Netherlands who operated and performed the sampling programme with the 
Ultraclean winch during this cruise. This work was made possibly 
specifically through funding from the DFG (CR145/lU and CR145/iS) and 
lfM-GEOMAR.


Fig. 3.19: Locations during ANT-XXIV/3 where vertical profiles were 
           taken for iron solubility measurements (left) Greenwich 
           meridian and (right) Drake Passage. One further station 
           was sampled in the centre of the Weddell Sea.


References

Byrne, RH., Yao, W., Luo, Y. and Wang, B., 2005. The dependence of 
    Fe(III) hydrolysis on ionic strength in NaCI solutions. marchem, 97: 
    34- 48.
Fischer, AC., Kroon, J.J., Verburg, T.G., Teunissen, 1. and Wolterbeek, 
    HI., 2007. On the relevance of iron adsorption to container materials 
    in small-volume experiments on iron marine chemistry: 55Fe-aided 
    assessment of capacity, affinity and kinetics. Marine Chemistry, 
    107(4): 533-546.
Hayase, K. and Shinozuka, N., 1995. Vertical distribution of 
    fluorescent organic matter along with AOU and nutrients in the 
    equatorial Central Pacific. Marine Chemistry, 48(3-4): 283290.
Hayase, K., Tsubota, H., Sunada, I., Goda, S. and Yamazaki, H., 1988. 
    Vertical distribution of fluorescent organic matter in the North 
    Pacific. Marine Chemistry, 25(4): 373.
Haygood, MG., Holt, P.D. and Butler, A., 1993. Aerobactin production by 
    a planktonic marine Vibrio sp. Limnol. Oceanogr., 38(5): 1091-1097.
Kuma, K., 2002. Variation in iron(III) solubility and iron 
    concentration in the northwestern North Pacific Ocean. Limnol. 
    Oceanogr., 47(3): 885-892.
Kuma, K., Nishioka, J. and Matsunaga, K., 1996. Controls on iron(III) 
    hydroxide solubility in seawater: The influence of pH and natural 
    organic chelators. Limnol. Oceanogr., 41(3): 396-407.
Liu, H. and Millero, F.J., 1999. The solubility of iron hydroxide in 
    sodium chloride solutions. Geochim. Cosmochim. Act., 63(19/20): 3487-
    3497.
Liu, X. and Millero, F.J., 2002. The solubility of iron in seawater. 
    Mar. Chem., 77: 43-54.
Martinez, J.S. et al., 2000. Self-Assembling Amphiphilic Siderophores 
    from Marine Bacteria. Science, 287:1245-1247.
McCormack, P., Worsfold, P.J. and Gledhill, M., 2003. Separation and 
    Detection of Siderophores Produced by Marine Bacterioplankton Using 
    High-Performance Liquid Chromatography with Electrospray Ionization 
    Mass Spectrometry. Anal. Chem., 75: 26472652.
Tani, H. et al., 2003. Iron(III) hydroxide solubility and humic-type 
    fluorescent organic matter in the deep water column of the Okhotsk Sea 
    and the northwestern North Pacific Ocean. Deep Sea Research Part I: 
    Oceanographic Research Papers, 50: 1063-1078.



3.2.4  Titanium in the Southern Ocean

       Peter Croot and Maija Heller
       IfM-GEOMAR

Objectives

As part of the IPY GEOTRACES ZERO and DRAKE programme we planned to 
take the first deep water measurements of titanium from the Southern 
Ocean. This information should allow us to better constrain the 
residence time of Ti in the ocean and to examine the fluxes and 
important processes occurring between the different oceanic basins.

Introduction

While it is established now that Fe can be a (co)limiting nutrient for 
phytoplankton in High Nutrient Low Chlorophyll (HNLC) regions of the 
world we still know little about the processes by which Fe is supplied 
to the ocean and how processes in the ocean scavenge/uptake or 
remineralize dissolved Fe. In many cases examination of other elements 
similar in chemistry to iron reveals more information on the key 
processes involved - such elements include Ti(IV), AI(III) and Mn(ll). 
By comparison of the concentrations of these strongly hydrolysed 
elements in the soluble, dissolved and particulate phases we hope to be 
able to better understand the processes affecting dust dissolution and 
particle scavenging in the surface ocean.

Titanium biogeochemistry in seawater has been studied very little in 
the open ocean, with only a single deep-water profile from the Pacific 
(Orians and Boyle, 1993; Orians et al., 1990) which showed picomolar 
concentrations in surface waters and increasing to -300 pM in deep 
waters. There have been a few more studies in enclosed seas (van den 
Berg et al., 1994) and estuaries (Skrabal, 1995; Skrabal and Terry, 
2002; Skrabal et al., 1992) but overall there is little information on 
the global Ti distribution in the ocean. Based on the work of Orians et 
al. (1990) Ti has a short residence time in the ocean and is enriched 
with depth due to remineralisation processes, there are presently no 
measurements from the Southern Ocean. For the Southern Ocean, the small 
data set from other regions hints that there may be significant 
differences in Ti concentrations between the different water masses 
present. In the present study, through the use of a new voltametric 
technique, developed at lfM-GEOMAR, that allows shipboard determination 
of pM levels of Ti, we were set to test this hypothesis.
By comparison of the chemistries and distributions of Ti, Al, Mn and Fe 
this GEOTRACES study in cooperation with NIOZ colleagues is aiming to 
improve our knowledge of the processes effecting trace metal 
distributions in the ocean with emphasis on dust deposition. The work 
performed during ANT-XXIV/3 was part of the German contribution for 
GEOTRACES and is also a continuation of similar earlier work performed 
on the Polarstern (ANT-XVIII/1 and ANT-XXIII/1) (Bowie et al., 2003; 
Sarthou et al., 2003) and the Meteor (M55) (Croot et al., 2004).

Work at sea

Water sampling

In the present work we obtained vertical profiles for Ti along the 
transects in the different regions of the Southern Ocean surveyed 
during ANT-XXIV/3 as part of the IPY GEOTRACES ZERO and DRAKE research 
programme. Depth resolved sampling was performed using water collected 
with both the regular CTD (Bl cast) and the NIOZ Ultraclean (Al cast) 
winch.

Trace metal sampling - analysis and examination of storage protocols
Samples were analysed for Ti(IV) using a new voltametric method 
developed at lfMGEOMAR (Croot, in preparation). All samples were 
analyzed unfiltered and within 24 hours of collection. Archive samples 
were also taken for later analysis in the laboratory in Kiel to examine 
possible storage artefacts as Ti is a ubiquitous component of the 
conventional trace metal sampling bottles as it is used a whitening 
agent (Ti02) or as a catalyst in the preparation of plastics (similar 
problems exist for Al).

Preliminary results

During ANT-XXIV/3 we made on board analysis of 15 stations for Titanium 
(Fig. 3.20) with 3 in the Drake Passage and 12 along the Greenwich 
meridian. Problems were encountered with the 3 stations taken from the 
ultraclean rosette, presumably due to its titanium construction but 
this may also have been due to sampling artefacts. The normal CTD (Bi 
cast) seemed to be fine for Ti sampling as was found in past cruises on 
the Polarstern. In general Ti increased with depth at all stations 
(Fig. 3.21) and further work will examine if there are discernable 
differences in the Ti content between the different deep water masses 
present along the transects.

Acknowledgements

The authors would like to show their deep thanks and appreciation to 
the crew of the Polarstern, for all their efforts in helping us 
throughout ANT-XXIV/3. Thanks also to the Chief Scientist, Dr. Eberhard 
Fahrbach and to the AWI Logistics Department for making this cruise 
possible. Funding for participation in this cruise was provided by the 
DFG (CR145/15) and lfM-GEOMAR.


Fig. 3.20: Bathymetrical map of the Atlantic sector of the Southern Ocean
           showing the location of stations sampled (blue triangles) during
           ANT-XXIV/3, the cruise track is also shown as a thin blue line.
Fig. 3.21: Profile of labile Ti in the water column near the shelf edge 
           close to Neumayer Station


References

Bowle, A.R. et al., 2003. Shipboard intercomparison of dissolved iron 
    in surface waters along a north-south transect of the tropical Atlantic 
    Ocean. Marine Chemistry, 84:19-34.
Croot, P.L., Streu, P. and Baker, AR., 2004. Short residence time for 
    iron in surface seawater impacted by atmospheric dry deposition from 
    Saharan dust events. Geophysical Research Letters, 31: L23S08, 
    doi.1029/2004GL020153.
Orians, K.J. and Boyle, E.A., 1993. Determination of Picomolar 
    Concentrations of Titanium, Gallium and Indium in Sea-Water by 
    Inductively-Coupled Plasma-Mass Spectrometry Following an 8-
    Hydroxyquinoline Chelating Resin Preconcentration. Analytica Chimica 
    Acta, 282(1): 63-74.
Orians, K.J., Boyle, E.A. and Bruland, K.W., 1990. Dissolved titanium 
    in the open ocean. Nature, 348: 322-325.
Sarthou, G. et al., 2003. Atmospheric iron deposition and sea-surface 
    dissolved iron concentrations in the East Atlantic. Deep-Sea Research, 
    50: 1339-1352.
Skrabal, S.A., 1995. Distributions of Dissolved Titanium in Chesapeake 
    Bay and the Amazon River Estuary. Geochimica Et Cosmochimica Acta, 
    59(12): 2449-2458.
Skrabal, S.A. and Terry, CM., 2002. Distributions of dissolved titanium 
    in porewaters of estuarine and coastal sediments. Marine Chemistry, 77: 
    109-122.
Skrabal, S.A., UlIman, W.J. and Luther, G.W., 1992. Estuarine 
    distributions of dissolved titanium. Marine Chemistry, 37: 83-103.
van den Berg, C.M.G., Boussemart, M., Yokoi, K., Prartono, 1. and 
    Campos, M.L.A.M., 1994. Speciation of aluminium, chromium and titanium 
    in the NW Mediterranean. Marine Chemistry, 45: 267-282.



3.2.5  Elemental ratios in particulate samples from the Atlantic sector of
       the Southern Ocean

       Peter Croot(1), Oliver Baars(1) and        (1)IfM-GEOMAR
       Rob Sherrell(2), not on board              (2)Rutgers University

Objectives

Our goal during ANT-XXIV/3 was to obtain samples for particulate metals 
from along the surveyed transects in order to have material from a 
variety of different oceanic environments in the Southern Ocean. 
Particulate samples were taken simultaneously, and in cooperation with 
the Dutch and German teams on board sampling in the dissolved phase in 
order to facilitate interpretation of the collected samples.

Introduction

Trace element ratios in particulate matter from surface waters reflect 
the nature of the particles themselves and can provide information on 
the processes that formed them. In particular in regions of high 
productivity the content of the mostly organic particles reflect the 
concentrations of the bioavailable fraction of the metals in seawater; 
this may include changes in the Cd:P or Zn:P ratio or in the Fe:P 
ratio. In contrast in shallow coastal regions, the particles may 
reflect more the inorganic/crustal signature of the nearby land or 
underlying sediments. The Rutgers group of Prof. Rob Sherrell have a 
strong history of developing and applying ICPMS techniques to the 
problem of element ratios in particulate matter (Berman-Frank et al., 
2001; Cullen and Sherrell, 1999; Cullen et al., 1999; Cullen et al., 
2003; Field et al., 1999; Sterner et al., 2004).

By measuring elemental ratios in particles collected during ANT-XXIV/3 
we hope to gather further information on the way in which particle 
supply and production, scavenging and dissolution controls dissolved 
metal concentrations in the open ocean and in turn how this may affect 
primary productivity.

Work at sea

Sampling Methodology

In the present work we obtained surface and near surface samples along 
the transects in the different regions of the Southern Ocean surveyed 
during ANT-XXIV/3 as part of the IPY GEOTRACES ZERO and DRAKE research 
programme. Sampling was conducted in two modes:

 (i) Occasional surface sampling from the Iron-FISH. This involved 
     collecting 24 L of seawater into a trace metal clean carboy and 
     filtering through either 13 mm quartz or polycarbonate filters. 
     All sample manipulations and filtration took place in a class 100 
     laminar flow bench. The filters were then later frozen and stored 
     until shipping for later analysis at Rutgers.
(ii) Depth resolved sampling was performed using water collected with 
     the NIOZ ultraclean roseefteAl cast. This involved filtering in 
     duplicate 2 L aliquots of seawater through; (1) a sandwiched pair 
     of 13 mm -1.0 pm pore size quartz fiber filter (QMA) and (2) a 
     sandwiched pair of 25 mm 0.45 pm and 50 pm Supor and Poretics plastic 
     filters fibre filters. All filtering was performed with a gentle 
     vacuum over pressure in a Class 100 laminar flow bench. Typically 
     samples were obtained from 25, 50, 100 and 200 m. The filters were 
     then frozen and stored until shipping for later analysis at Rutgers.

The collected samples will be analysed by ICP-MS in the laboratory at 
Rutgers. The present study is an extension of a pilot study examining the 
feasibility of combining this type of sampling with work on the dissolved 
metals in the water column carried out by the trace metal group at the lfM-
GEOMAR. This is an ongoing international collaboration between Germany and 
the USA as a contribution to GEOTRACES.

Work at sea

During ANT-XXIV/3 we collected over 60 samples from along the Greenwich 
meridian, in the Weddell Sea and through the Drake Passage for particulate 
metals from the Al casts and from the fish.

Preliminary results

As analysis of the collected samples is yet to be performed we have no 
preliminary results at this time.

Acknowledgements

The authors would like to show their deep thanks and appreciation to 
the crew of the Polarstern, for all their efforts in helping us 
throughout ANT-XXIV/3. Special thanks to the ultraclean winch team from 
NIOZ for their help with the sampling. Thanks also to the Chief 
Scientist, Dr Eberhard Fahrbach and to the AWI Logistics Department for
making this cruise possible. Funding for participation in this cruise 
was provided by the DFG (CR145/10) and lfM-GEOMAR.


References

Berman-Frank, I., Cullen, J.T., Shaked, Y., Sherrell, R.M. and 
    Falkowski, P.G., 2001. Iron availability, cellular iron quotas, and 
    nitrogen fixation in Trichodesmium. Limnology and Oceanography, 
    46:1249-1260.
Cullen, J.T. and Sherrell, R.M., 1999. Techniques for determination of 
    trace metals in small samples of size-fractionated particulate matter: 
    phytoplankton metals off central California. Marine Chemistry, 67: 233-
    247.
Cullen, J.T., Lane, 1W., Morel, F.M.M. and Sherrell, R.M., 1999. 
    Modulation of cadmium uptake in phytoplankton by seawater CO2 
    concentration. Nature, 402:165-167.
Cullen, J.T., Chase, Z., Coale, K.H., Fitzwater, S.E. and Sherrell, 
    R.M., 2003. Effect of iron limitation on the cadmium to phosphorous 
    ratio of natural phytoplankton assemblages from the Southern Ocean. 
    Limnology and Oceanography, 48: 1079-1087.
Field, M.P., Cullen, J.T. and Sherrell, R.M., 1999. Direct 
    determination of 10 trace metals in 50 uL samples of coastal seawater 
    using desolvating micronebulization sector field ICPMS. Journal of 
    Analytical Atomic Spectrometry, 14:1425-1431.
Sterner, R.W. et al., 2004. Phosphorus and trace metal limitation of 
    algae and bacteria in Lake Superior. Limnology and Oceanography, 49: 
    495-507.



3.2.6  The distribution of H202 in surface and deep waters of the Southern Ocean

       Maija Heller, Katrin Bluhm and Peter Croot
       IfM-GEOMAR

Objectives

H202 is a short lived photochemically produced trace oxidant found 
throughout the water column but predominantly in sunlit surface waters. 
Information on H202 concentrations allows us to constrain the oxidation time 
of reduced metal species (e.g. Cu(l), Fe(ll)) in the ocean where H202 can be 
the principal oxidant, this information is important for understanding the 
biogeochemical cycling of these metals. Furthermore H202 can be used as 
a tracer for vertical mixing in surface waters and/or a tracer of recent (last 
few days) rain or snow events. For ANT-XXIV/3 our objective was to make a 
synoptic survey of H202 throughout the Atlantic sector of the Southern Ocean and 
examine the influence of different biogeochemical provinces on its formation and 
decay.

Introduction

Hydrogen peroxide (H202) is the most stable intermediate in the four-
electron reduction of 02 to H20 and may function as an oxidant or a 
reductant. H202 is principally produced in the water column by 
photochemical reactions involving dissolved organic matter (DOM) and 02 
(Cooper et al., 1988; Scully et al., 1996; Yocis et al., 2000; Yuan and 
Shiller, 2001). Open ocean H202 concentrations show a distinct 
exponential profile with a maximum at the surface consistent with the
photochemical flux. Concentrations can reach up to 300 nmol Li in 
Equatorial and Tropical regions with high DOM concentrations such as in 
the Amazon plume in the Atlantic (Yuan and Shiller, 2001). In regions 
with low DOM and low sunlight, surface H202 levels are much lower with 
values in the Southern Ocean of 10-20 nmol L (Sarthou et al., 1997). 
Rainwater is a major potential source for H202 to surface seawater as it is 
preferentially removed from the atmosphere, relative to other peroxides, during 
convective events (Croot et al., 2004b). Due to its high solubility in water, 
scavenging of H202 in deep convection is around 55 - 70 % (Cohan et al., 1999). 
Mixing ratios of H202 in the marine troposphere show a strong latitude 
dependence with a maximum over the equator, suggesting that the air to 
surface flux at the equator should be high (Weller and Schrems, 1993).

H202 is also produced by biological processes in the ocean with 
observations from the Sargasso Sea (Palenik and Morel, 1988) and in 
phytoplankton cultures (Palenik et al., 1987) of production in the 
dark. Most studies to date have suggested that the major production 
pathway in the water column for H202 is from photochemical production, 
however in a few cases in the Southern Ocean, distinct H202 maxima at 
depth, corresponding to the chlorophyll maximum, suggest a significant 
biological source of H202 (Croot et al., 2004a). The 'dark decay life-
time' of H202 can vary from hours to weeks in the ocean (Petasne and 
Zika, 1997), but typically may be around 4 days in the open ocean 
(Plane et al., 1987). Overall the decay rate of H202 is apparently 
controlled by several factors: H202 concentration, colloid 
concentration, bacteria/cyanobacteria numbers and temperature (Wong et 
al., 2003; Yuan and Shiller, 2001).

Methods

H202 measurements in surface waters

Seawater samples were obtained using Niskin bottles on a standard CTD 
rosette. Samples were drawn into 100 mL low density brown polyethylene 
bottles which were impervious to light. Samples were analyzed within 1-
2 hours of collection where possible and were not filtered. In the 
present work H202 was measured using a flow injection chemiluminescence 
(FIA-CL) reagent injection method (Yuan and Shiller, 1999). In brief, 
the chemiluminescence of luminol is catalysed by the reaction of H202 
present in the sample with Co2 at alkaline pH. H202 standards were made 
by serial dilution from a primary stock solution (30 % Fluka - Trace 
Select). The concentration of the primary standard was determined by 
direct spectrophotometry of the solution (c = 40.9 mol L cm', (Hwang 
and Dasgupta, 1985)). Secondary standards were analysed with a 
spectrophotometric method using Cu(II) and 2,9-dimethyl-
1,10phenanthroline (Kosaka et al., 1998). Seawater samples were 
measured directly by FIA-CL, while rainwaters were diluted, up to 
1:100, with ultrapure water (18 MO). Sample concentrations were 
corrected for a small reagent blank (Yuan and Shiller, 1999). Samples 
were analyzed using 5 replicates: typical precision was 2-3 % through 
the concentration range 1-100 nM, the detection limit (3o) was 
typically 02 nmol Li.

Work at sea

During ANT-XXIV/3 samples were taken for H202 throughout the water 
column in connection with the normal Bi hydrocast as part of the IPY 
GEOTRACES ZERO & DRAKE programme. H202 profiles were measured at 38 
stations during the course of ANT-XXIV/3 from a wide range of upper 
ocean environments (Fig. 3.22). On previous research cruises we have 
concentrated exclusively on surface waters, however during ANT-XXIV/3 
we undertook full depth profiles to examine more closely the 
concentration of H202 in deep waters. As H202 is a short lived chemical 
species all sample analysis was performed at sea.

Preliminary results

Results gathered from ANT-XXIV/3 showed in general surface water 
concentrations of H202 were relatively low (20 - 40 nM) with one 
interesting exception in a high productivity region between 65° and 67° 
S (see Fig. 3.23). Where a major phytoplankton bloom was occurring, in 
this area H202 concentrations were elevated in the surface waters up to 
90 nM which is more typical of values found in Tropical regions. The 
possible reasons for this include (1) release of large amounts of 
photolabile DOC by the phytoplankton due to senescence or (2) direct 
biological production of H202 by phytoplankton cells. Deep water 
profiles often showed the presence of two distinct regions of elevated 
H202: at approximately 300 and 1,000 m and it is thought that these may 
be related to enzymatic reactions associated with the rem ineralization 
of organic matter that occurs at this depth.


Fig. 3.22: The location of stations sampled for H202 during ANT-XXIV/3: 
           (left) Greenwich meridian, (centre) Weddell Sea and (right) Drake 
           Passage.


Later work will include comparing the H202 profiles with measurements 
of other chemical and physical parameter made at each station. Using 
this approach it should be possible to determine the major processes 
(e.g. active mixing, rain inputs of H202, production via photolysis or 
phytoplankton production of H202) controlling the distribution of H202 
in both the surface and deep waters in the Southern Ocean along the 
ANT-XXIV/3 transects.


Fig. 3.23: The vertical distribution of H202 from some representative 
           stations during ANT-XXI V/3: top left: Near surface distribution 
           of H202 along the Greenwich meridian in a region impacted by a 
           large phytoplankton bloom. Top right: Full water column profile 
           from the same station. Bottom left: Typical profile for Polar 
           waters not impacted by phytoplankton blooms. Bottom right: H202 
           profile from the edge of the ice shelf showing the deeper mixing 
           that occurs here.


Acknowledgements

The authors would like to show their deep thanks and appreciation to 
the crew of the Polarstern, for all their efforts in helping us 
throughout ANT-XXIV/3. Thanks also to the Chief Scientist, Dr. Eberhard 
Fahrbach and to the AWI Logistics Department for making this cruise 
possible. Funding for participation in this cruise was provided by the 
DFG.


References

Cohan, D.S., M.G. Schultz, D.J. Jacob, B.G. Heikes, and D.R. Blake, 
    Convective injection and photochemical decay of peroxides in the 
    tropical upper troposphere: Methyl iodide as a tracer of marine 
    convection, Journal of Geophysical Research-Atmospheres, 104 (D5), 
    5717-5724, 1999.
Cooper, W.J., R.G. Zika, R.G. Petasne, and J.M.C. Plane, Photochemical 
    Formation of H202 in Natural Waters Exposed to Sunlight, Environmental 
    Science and Technology, 22, 11561160, 1988.
Croot, PL., P. Laan, J. Nishioka, V. Strass, B. Cisewski, M. Boye, K. 
    Timmermans, R. Bellerby, L. Goldson, and H.J.W. de Baar, Spatial and 
    Temporal distribution of Fe(II) and H202 during EISENEX, an open ocean 
    mesoscale iron enrichment, submitted to Marine Chemistry, 2004a.
Croot, PL., P. Streu, I. Peeken, K. Lochte, and A.R. Baker, Influence 
    of ITCZ on H202 in near surface waters in the equatorial Atlantic 
    Ocean, Geophysical Research Letters (accepted), 2004b.
Hwang, H., and P.K. Dasgupta, Thermodynamics of the Hydrogen Peroxide-
    Water System, Environmental Science and Technology, 19, 255-258, 1985.
Kosaka, K., H. Yamada, S. Matsui, S. Echigo, and K. Shishida, 
    Comparison among the methods for hydrogen peroxide measurements to 
    evaluate advanced oxidation processes: Application of a 
    spectrophotometric method using copper(II) ion and 2.9 dimethyl-
    1,10-phenanthroline, Environmental Science & Technology, 32 (23), 3821-
    3824, 1998.
Palenik, B., and F.M.M. Morel, Dark production of H202 in the Sargasso 
    Sea, Limnology and Oceanography, 33, 1606-1611, 1988.
Palenik, B., O.C. Zafiriou, and F.M.M. Morel, Hydrogen peroxide 
    production by a marine phytoplankter, Limnology and Oceanography, 32, 
    1365-1369, 1987.
Petasne, R.G., and R.G. Zika, Hydrogen peroxide lifetimes in south 
    Florida coastal and offshore waters, Marine Chemistry, 56 (3-4), 215-
    225, 1997.
Plane, J.M.C., R.G. Zika, R.C. Zepp, and L.A. Burns, Photochemical 
    modeling applied to natural waters, in Photochemistry of environmental 
    aquatic systems, edited by R.G. Zika, and W.J. Cooper, pp. 215-224, 
    American Chemical Society, Washington D.C., 1987.
Sarthou, G., C. Jeandel, L. Brisset, D. Amouroux, T. Besson, and O.F.X. 
    Donard, Fe and H202 distributions in the upper water column in the 
    Indian sector of the Southern Ocean, Earth and Planetary Science 
    Letters, 147, 83-92, 1997.
Scully, N.M., D.J. McQueen, D.R.S. Lean, and W.J. Cooper, Hydrogen 
    peroxide formation: The interaction of ultraviolet radiation and 
    dissolved organic carbon in lake waters along a 43-75 degrees N 
    gradient, Limnology and Oceanography, 41(3), 540-548, 1996.
Weller, R., and 0. Schrems, H202 in the Marine Troposphere and Seawater 
    of the Atlantic Ocean, Geophysical Research Letters, 20, 125-128, 1993.
Wong, G.T.F., W.M. Dunstan, and D.B. Kim, The decomposition of hydrogen 
    peroxide by marine phytoplankton, Oceanologica Acta, 26(2), 191-198, 
    2003.
Yocis, B.H., D.J. Kieber, and K. Mopper, Photochemical production of 
    hydrogen peroxide in Antarctic Waters,, Deep Sea Research Part I : 
    Oceanographic Research, 47(6), 10771099,2000.
Yuan, J., and A.M. Shiller, Determination of Subnanomolar Levels of 
    Hydrogen Peroxide in Seawater by Reagent-Injection Chem ilum inescence 
    Detection, Analytical Chemistry, 71, 1975-1980, 1999.
Yuan, J., and A.M. Shiller, The distribution of hydrogen peroxide in 
    the southern and central Atlantic ocean, Deep-Sea Research II, 48, 
    2947-2970, 2001.


3.2.7  Iodide and iodate speciation in the Southern Ocean

       Katrin Bluhm and Peter Croot
       IfM-GEOMAR

Objectives

Iodine is potentially a key element for climate change as iodine 
emissions from the ocean strongly influence the formation of new 
aerosol particles with impacts on cloud formation and radiative 
balances. The source and mechanism of iodine emissions from the ocean 
is poorly understood, as are other more fundamental aspects of iodine 
biogeochemistry in seawater such as the cycling between the major 
iodine species; iodate and iodide. In the proposed work we will 
investigate the biogeochemistry of iodine in the poorly studied waters 
of the Southern Ocean. Central to this work will be investigations into 
the underlying mechanism behind the distribution and speciation of 
iodine species in the Atlantic sector of the Southern Ocean. During the 
Polarstern cruise ANT-XXIV/3 ZERO&DRAKE the speciation and distribution 
of iodine species were examined across gradients of iron concentration 
and phytoplankton abundance in seawater; ranging from an open ocean 
region along the prime meridian, the Weddell Sea and Drake Passage and 
near several Antarctic islands.

Introduction

Dissolved iodine is ubiquitous and quasi-conservative in seawater and 
exists predominantly as iodide () and iodate (103), with a total 
dissolved concentration of about 470 nM (Salinity 35). In fully 
oxygenated seawater (pH 8.0, pG 12.5) 103 is the thermodynamically 
stable form of iodine (Wong, 1991). Molecular iodine (12) is only a 
transient species due to its fast reactivity with organic matter 
(Truesdale, 1974) and loss to the atmosphere (Leblanc et al., 2006). In 
surface waters r concentrations reach 50-150 nM, probably through 
biological reduction of 103 and this occurs to the greatest extent in 
tropical and subtropical waters (Jickells et al., 1988). In deep 
waters, below the euphotic zone, iodide decreases to low levels (< 5 
nM), while iodate increases to a relatively constant level of about 450 
nM. Attempts to explain iodate reduction in the euphotic zone have 
linked it to phytoplankton growth, microbial respiration (Truesdale and 
Bailey, 2002), photochemistry (Spokes and Liss, 1996), and sediment- 
water interactions (Anschutz et al., 2000).

The biogeochemistry of iodine in the Southern Ocean is relatively 
unknown at present with only a single published study from the WeddeD 
Sea (Campos et al., 1999) which ran along the WOCE A23 transect from 
the Weddell Sea at 75°S to about 25°S in March-May 1995. In this work 
Campos et al. (1999) found a systematic increase in iodide in surface 
waters (0-100 m) from south to north. The lowest values of about 20 nM 
iodide in surface waters were observed at stations south of the Polar 
Front. North of the Polar and Subtropical Front values increased up to 
100 nM of iodide, where at depth greater than 100 m iodide 
concentrations dropped down again to less than 20 nM and continue to 
decrease rapidly with depth until the detection limit of the method 
(0.08 nM with a precision better than ±5 %).

Campos et al. (1999) interpreted their results from north to south as a 
lower iodide production south of the Polar Front where surface waters 
contained high nitrate concentrations, a surprisingly similar 
conclusion to Mclaggart et al. (1994) made for the Tropics, this is 
however based on the assumption that iodate reduction is related to 
nitrate reduction via the action of nitrate reductase. They also 
suggested that the cycling of iodine was different in the various 
sectors of the Southern Ocean resulting in different nitrate: iodide 
ratios in the surface waters. Unfortunately Campos et al. had no 
supporting productivity or chlorophyll data for their work.

Truesdale et al. (2003) followed the iodate and total iodine 
concentrations in a mesocosm experiment in Antarctica. They only found 
lithe or no change in the iodate concentrations and their results do 
not support the belief that changes in iodine speciation is only due to 
phytoplankton growth. These results are somewhat contradictory to 
laboratory studies made by Wong et al. (2002) and Chance et al. (2007) 
in which both researchers found a change in iodine speciation during 
the growth of Antarctic species. Globally iodide production has been 
suggested as both an indicator of new production (Campos et al., 1996) 
and of regenerated production (Tian et al., 1996) and the 
interpretation hinges on whether iodide production is related to 
nitrate uptake as suggested by Wong (Wong, 2001) or is related to other 
decomposition processes. It is thus unclear at present exactly what 
processes control lodate biogeochemistry in the Southern Ocean.

The presence of iodide in seawater is a necessary precursory for the 
production of iodinated organic compounds, many of which are volatile. 
Iodine chemistry in the atmosphere is also important as iodine released 
from the ocean is believed to be a major source of new particles to the 
atmosphere (ODowd et al., 2002) which may alter the radiative forcing 
in the atmosphere by acting as cloud condensation nuclei. The main flux 
from the ocean is from the air-sea gas exchange of iodinated organic 
compounds such as methyl iodide (CH3I) or diodomethane (CH212). These 
iodinated compounds may be formed in seawater by reactions between 
organic compounds and iodine species via photolysis reaction (Moore, 
2006; Richter and Wallace, 2004) or bacterial action (Amachi et al., 
2001; Manley, 2002). Gases such as CH3I and CH212 are relatively short-
lived in the atmosphere as sunlight readily breaks the C-I bond 
producing I radicals (Martino et al., 2006) which form particulate 
aerosol iodine species (Baker et al., 2000). Thus there has been 
considerable interest in the flux of methyl iodide from Southern Ocean 
waters with this area being identified as a major source to the 
atmosphere (Cox et al., 2005) with large fluxes being observed at the 
Antarctic Peninsula (Reifenhauser and Heumann, 1992) and more recently 
in the Weddell Sea (Carpenter et al., 2007). Enhanced production of 
some iodinated gases was also observed during the recent Southern Ocean 
iron enrichment experiments: EisenEx (Chuck et al., 2005) and SOFeX 
(Wingenter et at., 2004).

Work at sea

Analytical Measurements

Seawater samples (unfiltered) were obtained using Niskin bottles on the 
standard CTD rosette from all depths during the Bi cast of the IPY 
GEOTRACES ZERO & DRAKE programme. Samples were drawn into 100 mL low density 
brown polyethylene bottles which were impervious to light. Samples for iodide 
were analyzed by cathodic stripping square wave voltammetry (Luther et 
al., 1988), using a pAutolab Ill (Ecochemie) combined with a VA663 
electrode (Metrohm), within 3-4 hours of collection. lodate was 
analyzed by spectrophotometry (Truesdale, 1978; Truesdale and Smith, 
1979), by conversion to l3, using 10 cm cells with an Ocean Optics 
USB4000 spectrophotometer. All analysis was performed under clean 
conditions in the Class 5 clean room container from the lfM-GEOMAR.

Iodide profiles were measured at 30 stations during the course of ANT-
XXVI/3 (Fig. 3.24). This included 15 stations on the transect to and 
along the Greenwich meridian, 2 stations in the coastal waters close to 
Neumayer, 6 in the Weddell Sea and 7 in the Drake Passage. Sea ice 
samples were also collected in the coastal waters close to Neumayer, 
melted and analysed on board. All sample analysis was performed at sea.

Preliminary results

Iodide concentrations were relatively low (0-40 nM) along the Greenwich 
meridian, and a typical profile for this region is shown in Fig. 3.25. 
The highest concentrations for iodide during this cruise were found 
along the coastal shelf of South America at the end of the transect 
across the Drake Passage. Initial comparisons with macronutrient data 
suggest that iodide was weakly related to primary production and that 
physical mixing appeared to play a strong role in shaping the iodide 
profile. Of most interest however, was the discovery of elevated iodide 
at depths below the euphotic layer, which strongly suggests that 
regeneration processes are responsible for the iodide production at 
these depths. The iodate data gathered on board also supported this 
view and indicated that overall iodine was conservative in these 
waters.


Fig. 3.24: The location of stations sampled for iodine speciation 
           (iodide & iodate) during ANT-XXIV/3: (left) Greenwich meridian, 
           (centre) Weddell Sea and (right) Drake Passage
Fig. 3.25: A representative profile for iodide in Polar waters from 
           along the Greenwich meridian


Acknowledgments

The authors would like to show their deep thanks and appreciation to 
the crew of the Polarstern, for all their efforts in helping us 
throughout ANT-XXIV/3. Thanks also to the Chief Scientist, Dr Eberhard 
Fahrbach and to the AWI Logistics Department for making this cruise 
possible. Funding for participation in this cruise was provided by
the DFG and lfM-GEOMAR.


References

Amachi, S., Kamagata, Y., Kanagawa, 1. and Muramatsu, Y., 2001. 
    Bacteria Mediate Methylation of Iodine in Marine and Terrestrial 
    Environments. AppI. Environ. Microbiol., 67(6): 2718-2722.
Anschutz, P., Sundby, B., Lefrancois, L., Luther III, G.W. and Mucci, 
    A., 2000. Interactions between metal oxides and species of nitrogen and 
    iodine in bioturbated marine sediments. Geochimica et Cosmochimica 
    Acta, 64: 2751-2763.
Baker, AR., Thompson, D., Campos, M.L.A.M., Parry, S.J. and Jickells, 
    ID., 2000. Iodine concentration and availability in atmospheric 
    aerosol. Atmospheric Environment, 34: 4331-4336.
Campos, M., Farrenkopf, AM., Jickells, T.D. and Luther, G.W., 1996. A 
    comparison of dissolved iodine cycling at the Bermuda Atlantic Time-
    Series station and Hawaii Ocean Time-Series Station. Deep-Sea Research 
    Part li-Topical Studies In Oceanography, 43(23): 455-466.
Campos, M., Sanders, R. and Jickells, T., 1999. The dissolved iodate 
    and iodide distribution in the South Atlantic from the Weddell Sea to 
    Brazil. Marine Chemistry, 65(3-4): 167-175.
Carpenter, L.J., Wevill, D.J., Palmer, C.J. and Michels, J., 2007. 
    Depth profiles of volatile iodine and bromine-containing halocarbons in 
    coastal Antarctic waters. Marine Chemistry, 103(3-4): 227.
Chance, R., Malm, G., Jickells, T. and Baker, AR., 2007. Reduction of 
    iodate to iodide by cold water diatom cultures. Marine Chemistry, 
    105(1-2): 169-180.
Chuck, AL., Turner, S.M. and Liss, P.s., 2005. Oceanic distributions 
    and air-sea fluxes of biogenic halocarbons in the open ocean. Journal 
    Of Geophysical Research-Oceans, 1 10(C10).
Cox, ML., Sturrock, GA., Fraser, P.J., Siems, S.T. and Krummel, PB., 
    2005. Identification of regional sources of methyl bromide and methyl 
    iodide from AGAGE observations at Cape Grim, Tasmania. Journal Of 
    Atmospheric Chemistry, 50(1): 59-77.
Jickells, ID., Boyd, 5.5. and Knap, AH., 1988. Iodine Cycling in the 
    Sargasso Sea and the Bermuda Inshore Waters. Marine Chemistry, 24: 61-
    82.
Leblanc, C. et al., 2006. Iodine transfers in the coastal marine 
    environment: the key role of brown algae and of their vanadium-
    dependent haloperoxidases. Biochimie, 88(11): 17731785.
Luther, G.W., Swartz, C.B. and UlIman, W.J., 1988. Direct determination 
    of Iodide in Seawater by Cathodic Stripping Square Wave Voltammetry. 
    Analytical Chemistry, 60: 1721-1724.
Manley, S.L., 2002. Phytogenesis of halomethanes: A product of 
    selection or a metabolic accident? Biogeochemistry, 60(2): 163-180.
Martino, M., Liss, P.S. and Plane, J.M.C., 2006. Wavelength-dependence 
    of the photolysis of diiodomethane in seawater. Geophysical Research 
    Letters, 33(6).
Mclaggart, AR., Butler, E.C.V., Haddad, P.R. and Middleton, J.H., 1994. 
    Iodide And lodate Concentrations In Eastern Australian Subtropical 
    Waters, With Iodide By Ion Chromatography. Marine Chemistry, 47(2): 
    159-172.
Moore, R.M., 2006. Methyl halide production and loss rates in sea water 
    from field incubation experiments. Marine Chemistry, 101(3-4): 213.
O'Dowd, C.D. et al., 2002. Marine aerosol formation from biogenic 
    iodine emissions. Nature, 417: 632-636.
Reifenhauser, W. and Heumann, KG., 1992. Determinations Of Methyl-
    Iodide In The Antarctic Atmosphere And The South Polar Sea. Atmospheric 
    Environment Part AGeneral Topics, 26(16): 2905-2912.
Richter, U. and Wallace, D.W.R., 2004. Production of methyl iodide in 
    the tropical Atlantic Ocean. Geophysical Research Letters, 31(23).
    Spokes, L.J. and Liss, P.S., 1996. Photochemically induced redox 
    reactions in seawater.2. Nitrogen and iodine. Marine Chemistry, 54(1-2): 
    1-10.
Tian, R.C. et al., 1996. Iodine speciation: A potential indicator to 
    evaluate new production versus regenerated production. Deep-Sea 
    Research Part I-Oceanographic Research Papers, 43(5): 723-738.
Truesdale, V.W., 1974. The chemical reduction of molecular iodine in 
    seawater. Deep Sea Research and Oceanographic Abstracts, 21(9): 761.
Truesdale, V.W., 1978. The Automatic Determination of lodate and Total-
    Iodine in Seawater. Marine Chemistry, 6: 253-273.
Truesdale, V.W. and Bailey, G.W., 2002. Iodine distribution in the 
    Southern Benguela system during an upwelling episode. Continental Shelf 
    Research, 22(1): 39-49.
Truesdale, V.W., Kennedy, H., Agusti, S. and Waite, T.J., 2003. On the 
    relative constancy of iodate and total-iodine concentrations 
    accompanying phytoplan kton blooms initiated in mesocosm experiments in 
    Antarctica. Limnology And Oceanography, 48(4): 1569-1574.
Truesdale, V.W. and Smith, C.J., 1979. A Comparative Study of Three 
    Methods for the Determination of lodate in Seawater. Marine Chemistry, 
    7: 133-139.
Wingenter, OW. et al., 2004. Changing concentrations of CO, CH4, C5H8, 
    CH3Br,CH3I, and dimethyl sulfide during the southern ocean iron 
    enrichment experiments. Proceedings Of The National Academy Of Sciences 
    Of The United States Of America, 101(23): 85378541.
Wang, G.T., Piumsamboon, A.U. and Dunstan, W.M., 2002. The 
    transformation of iodate to iodide in marine phytoplankton cultures. 
    Marine Ecology Progress Series, 237: 27-39.
Wang, G.T.F., 1991. The Marine Geochemistry Of Iodine. Reviews In 
    Aquatic Sciences, 4(1): 45-73.
Wong, G.T.F., 2001. Coupling iodine speciation to primary, regenerated 
    or 'new' production: a re-evaluation. Deep-Sea Research Part I-
    Oceanographic Research Papers, 48(6): 1459-1476.



3.2.8  Measurements of AOT (Aerosol Optical Thickness) over the Southern Ocean

       Peter Croot and Maija Heller, IfM-GEOMAR
       not on board: A. Smirnav, NASA/Goddard Space Flight Center

Objectives

There is a currently a lack of ground truth information for 
measurements of AOT (Aerosol Optical Thickness) from the Southern 
Ocean. While satellite measurements of AOT are possible at present 
through a number of dedicated satellites (MODIS AQUA and TERRA) data 
interpretation is reduced due to persistent cloud cover and reflections 
from sea ice and waves. Direct measurements of AOT from the surface 
using the sun as a light source are possible using small handheld 
devices such as the MICROTOPS and provide a useful dataset to validate 
retrieval algorithms for satellite estimation of AOT as well as 
providing instantaneous information for shipboard users. For ANT-XXIV/3 
we undertook measurements of AOT when the weather permitted to provide 
baseline data for improving satellite retrievals and for assessment of 
any contribution from Patagonian dust to the aerosol loading over the 
Southern Ocean.

Transport of airborne dust from the continents provides a route by 
which Fe and other trace elements can enter remote surface ocean 
waters. This transport can be of particular importance for supplying 
iron to HNLC regions where Fe is the limiting nutrient. For the 
Atlantic sector of the Southern Ocean and the Weddell Sea it is 
suspected that much of the iron supplied to surface waters originates 
from Patagonia but the supply is extremely episodic (Erickson Iii et 
al. 2003; Gaiero et al. 2004; Gasso and Stein 2007).

Work at sea

During ANT-XXIV/3 discrete AOT measurements were made using a MICROTOPS 
II kindly loaned by the NASA/Goddard Space Flight Centre as part of the 
AERONET Maritime Aerosol Network programme
(http :llaeronet. gsfc. nasa. gov/new_web/mariti me_aerosol_network. 
html).

The MICROTOPS Ills a handheld instrument that is well characterised for 
AOT measurements (Ichoku et al. 2002) and is capable of being used on 
moving platform such as a ship at sea (Porter et al. 2001), though the 
data does require some corrections because of ship movement 
(Knobelspeisse et al. 2003).

Over 1400 individual measurements were collected during the course of 
ANT-XXIV/3 corresponding to the periods when the sun was visible and 
not obscured by clouds. Problems were encountered with rough sea states 
and high winds but in general observations were easily made.

Preliminary results

The preliminary data indicated extremely low AOT over the course track 
most of the time suggesting there was little dust encountered during 
the cruise as might be expected for this remote region. Slightly 
elevated AOT was found along the Greenwich meridian at the location of 
the phytoplankton bloom and this may be due to increased biogenic 
aerosol production during the bloom though this must be confirmed by 
later comparison with satellite data collected at the same time. 
Further Satellite data relayed to us during the cruise (Santiago Gasso 
- NASA) indicated that there were some minor dust events from Patagonia 
occurring during the duration of ANT-XXIV/3 but back trajectories 
indicated a mostly easterly course which did not intersect with the 
ships position at any time. The collected AOT data will be further 
processed before release to the web.

References

Erickson Iii, D. J., J. L. Hernandez, P. Ginoux, W. W. Gregg, C. 
    Mcclain, and J. Christian. 2003. Atmospheric iron delivery and surface 
    ocean biological activity in the Southern Ocean and Patagonian region. 
    Geophysical Research Letters 30: 1609, doi:1 610.1 02912003GL01 7241.
Gaiero, D. M., P. J. Depetris, J. L. Probst, S. M. Bidart, and L. 
    Leleyter. 2004. The signature of river- and wind-borne materials 
    exported from Patagonia to the southern latitudes: a view from REEs and 
    implications for paleoclimatic interpretations. Earth And Planetary 
    Science Letters 219: 357-376.
Gasso, S., and A. F. Stein. 2007. Does dust from Patagonia reach the 
    sub-Antarctic Atlantic Ocean? Geophysical Research Letters: L01801, doi 
    :01810.01 029/02006G L027693.
Ichoku, C. and others. 2002. Analysis of the performance 
    characteristics of the five-channel Microtops II Sun photometer for 
    measuring aerosol optical thickness and precipitable water vapor. 
Journal of Geophysical Research 107: 4179, doi:4110.1029/2001JD001302.
    Knobelspeisse, K. D., C. Pietras, and G. S. Fargion. 2003. Sun-
    Pointing-Error Correction for Sea Deployment of the MICROTOPS II 
    Handheld Sun Photometer. Journal of Atmospheric and Oceanic Technology 
    20: 767-771.
Porter, J. N., M. Miller, C. Pietras, and C. Motell. 2001. Ship-Based 
    Sun Photometer Measurements Using Microtops Sun Photometers. Journal of 
    Atmospheric and Oceanic Technology 18: 765-774.



3.3  ISOTOPES BY THE AWI-TEAM

     Ingrid Stimac(1), Celia Venchiarutti1,       (1)Alfred -Wegener-Institut
     Maya Robert(1), Pinghe Cai(3),               (2)IFM-GEOMAR
     Torben Stichel(2), Elizabeth Sweet(1).       (3)Xiamen University, China
     Not on board: 
     Michiel Rutgers van der Loeff(1)
     Martin Frank 2) Michael Staubwasser 
     (Univ. Cologne), Christina de la Rocha(1), 
     Dieter Wolf-Gladrow(1)

Background and general objectives

Uranium-series radionuclides are powerful tracers for the rate of 
transport processes in the ocean. We wish to measure the distribution 
of U-series isotopes along the Greenwich meridian and in the Drake 
Passage. The sampling will be coordinated with sampling of other trace 
elements. This joint sampling allows us to directly apply the 
information on particle dynamics (aggregation, disaggregation and 
particle sinking rates) and terrigenous input that we will obtain from 
the distribution of thorium isotopes and 231Pa, to the transport of 
other tracers. Similarly, we will be able to confront the results on 
water mass ventilation and upwelling, as we will derive from 
230Th/231Pa and 227 Ac distributions, with hydrographic data and the 
conclusions drawn from other tracers described in parallel proposals 
(Nd/Hf isotopes; freons). The data will be interpreted along with other 
tracer data in (inverse) GCM models. We expect that this approach will 
improve our ability to use a set of tracers as more reliable proxies 
for past ocean climate.



3.3.1  234Th as tracer of export production of POC

       Ingrid Stimac(1), Pinghe Cai(2),           (1)Alfred-Wegener-Institut
       Michiel Rutgers van der Loeff(1)           (2)Xiamen University, China

Objectives

The objectives of the project are:

1) to acquire accurate estimates of upper ocean POC export fluxes in 
   the Southern Ocean;
2) to infer the export fluxes of some particle-reactive 
   elements/compounds (i.e., Fe, Al, Mn, Cu, Cd, Ni, Zn, and Ag) that will 
   be measured by other researchers in the same regions (see section on 
   trace metals above; and
3) to carry out the intercomparison of POC export studies between 
   234Th/238U and 210Po/210Pb methods.

Work at sea

1) A total of 20 depth profiles of total 234Th in 4-L water samples 
   have been collected with the CTD.
2) Deployment of in-situ pumps in order to obtain size-fractionated 
   samples of suspended particles and determine the POC/234Th ratio in 
   those size fractions.

In parallel to the sampling in Rosette casts we have used our automated 
234Th analyser to obtain the distribution of particulate and dissolved 
234Th in the surface water at higher spatial resolution. Samples were 
drawn every 4 hours from the ships seawater supply.

The distribution of particulate 234Th gave a consistent picture. We 
have the experience that particulate 234Th is an indirect 
representation of the suspended load in seawater. Plankton blooms are 
e.g. usually reflected in an increase of particulate 234Th As we 
approached the shelf ice a prominent drop in particulate 234Th showed 
the presence of very clear water.

The automated analysis of dissolved 234Th involves a coprecipitation of 
Th with Mn02. The efficiency of this coprecipitation has been monitored 
by a continuous intercalibration programme with the manual 4-L method 
described above. The results of this programme will only be available 
after the measurement of a 230Th yield tracer at AWL Dissolved and 
total 234Th data from the automated analysis were therefore not yet 
available on board.


Preliminary results

The depth profiles of total 234Th show that 234Th deficit varied 
substantially over the upper Southern Ocean (Fig. 326). This indicates 
remarkable variations in POC export in the Southern Ocean.


Fig. 3.26: Depth profiles of total 234That Station 101, 118 and 178 in the 
           Southern Ocean. Note that the recovery for 234 Th is yet to be
           determined.



3.3.2  Analysis of multiple thorium isotopes and 231pa

       Ingrid Stimac(1), Celia Venchiarutti(1),   (1)Alfred-Wegener-Institut
       Pinghe Cai (2), Michiel Rutgers van der    (2)Xiamen University, China
       Loeff(1)

Objectives

230Th and 231Pa are both the decay products of soluble and 
conservatively distributed uranium isotopes (234U and 235U). Th and Pa 
are produced at a fixed known rate in the ocean and are both sensitive 
to scavenging. The distributions of 231Pa and 230Th are controlled by 
particle flux and boundary scavenging. Thus, changes in the water 
column distribution of these isotopes can be interpreted as indication 
of changes in water mass ventilation and in particle flux. If no 
scavenging and/or recent ventilation of water masses occurs, the 
production rate of Th and Pa along the water column is constant, 
resulting in a distribution that increases with increasing depth. With 
a residence time of 50 to 100 years, 230Th is more reactive than 231Pa 
(residence time in seawater of approximately 200 years) and will trace 
more rapid and recent processes.

We wish to determine 231Pa and 230Th in filtered seawater and 
suspended particulate matter along the Greenwich meridian and in the 
Drake Passage.

The distribution of multiple Th isotopes over particulate and dissolved 
phase can be used to derive adsorption and desorption rates. When the 
particles are separated according to grain size before analysis (e.g. 
with a 50 µ screen), then the isotopes can be used to constrain the 
settling velocity of small and large particles in the upper 1000 m of 
the water column. If the distribution of Th isotopes is obtained over 
various size fractions it is possible to derive aggregation and 
disaggregation rates.

Work at sea

Dissolved

231Pa and 230Th analysis requires collection of 20 L of filtered (<1 
pm) seawater. The 20 L are collecting using the Niskin bottles into 
acid-cleaned collapsible cubitainers, filtered through a 142 mm 
diameter Supor(r)-450 filter of 0.45 µm pore size (Pall). Then, all 
seawater samples are stored acidified (with concentrated distilled 
HNO3), without addition of any tracers. The Supor(r)-450 filters are 
stored wet in special plastic bags and stored at 4°C. All the samples 
will be further processed at the home laboratory (addition of the 
tracers, coprecipitation, chromatographic extraction and spectrometric 
measurements).

About 8-11 samples are collected at each super station, giving a full 
water column profile with a good resolution. Therefore, 13 profiles were 
realised, 6 along the Greenwich meridian (Fig. 3.27) 2 in the Weddell Sea 
(Tab. 3.2) and 5 at Drake Passage. At some stations, duplicates were 
achieved. Thus, in the scope of GEOTRACES intercalibration and the 
BONUS-GOODHOPE expedition, 3 duplicates were collected at Station 113 
(20/02/08, at 1,000 m, 500 m and 380 m for the 231Pa and 230Th 
analysis that will be achieved at LEGOS in Toulouse (Catherine Jeandel 
and Matthieu Roy-Barman). Three duplicates were also collected at the same 
location (on 12/03/08 at 52°59'S and 0°0'E) by the BONUS-GOODHOPE 
expedition. An extra station was realised near the ice shelf at 70°34'S 
and 8°7'E on 5/03/08. Surface samples were collected with the IFISH and 
filtered like the other samples on Supor(r)-450 filters.


Tab. 3.2: List of all the 20 L samples collected for the Nd, Th and Pa 
          analysis at the different stations with the indicated depths (from 10 
          Feb. 08 to 16 Apr. 08). Values followed by an "@" are depths that 
          need to be checked for precision, by a "#" are the duplicated samples 
          for the GEOTRACES intercomparison and a "*", the duplicated 
          depth/samples.


11/02/2008  13/02/2008  13/02/2008  17/02/2008  20/02/2008  24/02/2008  05/03/2008  09/03/2008  12/03/2008
 Test stn    Test stn     4513m       2189m       2462m       4177m        131m       4487m       1961m
  Stn 97      Stn 99     Stn 101     Stn 104     Stn 113     Stn 131      Stn 154    Stn 161     Stn 178
   100@        2000     Bottom-100  Bottom-100  Bottom-100  Bottom-100    Bottom    Bottom-100   Bottom
               1000        3000        2500        1500        3800         10         3400        1500
                           2000        2000        1000        3000                    2400        1000*
                           1000        1250        1000#       2000                    1200         800
                            750         750         750        1000                     800         500*
                            500         500         500         500                     440         200
                            200         200         500#        250                     200         100*
                             75          75         380         100                     100          50
                                     surface        380#     surface
                                                    150      surface
                                                     70      surface                            duplicates*

                        18/03/2008  29/03/2008  2-3/04/2008  5/04/2008  7/04/2008   9/04/2009   11/04/2010
                          4897m        380m@       3475m       3785m      3490m       3999m        3800m
                         Stn 193      Stn 222     Stn 230     Stn 236    Stn 241     Stn 244      Stn 250
                         Bottom       Bottom      Bottom      Bottom     Bottom      Bottom       Bottom
                           4000         280        3000        2800       2800         3500        3000
                           3200         180        2500        1750       2000         3000        2200
                           2200         100        2000        1000       1250         2500        1600
                           1200         50         1500         400        750         1750         900
                            800                    1000         250        480         1250         500
                            500                     500         120        150          750         300
                            200                     400          50         50          500         150
                             50                     250                                 200*      
                                                    150                                  75      
                                                     50                                  25      

                                                                                    duplicates*


So far, 119 samples were collected for the dissolved 231Pa and 230Th analysis. 
13 super stations have been realised, 2 test stations, a small station close to 
the Antarctic ice shelf and some surface samples collected from the IFISH.


Fig. 3.27: Sampling location and depths along the Greenwich meridian


Particulate

Due to the 231Pa and 230Th low concentrations in particles (10 times less than 
in the dissolved phase), their analysis requires large volumes of filtered 
seawater of about 500-1,000 L.

Size-fractionated particulate material sampling was achieved, using 6 
"Challenger" in-situ pumps. The filter holders of these pumps are set up with a 
stack of 3 different filters of 142 mm diameter and separated by grids. The 
lower filter is a Supor(r)-800 filter (Pall) of 0.80 pm pore size on which the 
small particle fraction (0.8 - 10 μm) is collected. Then, above the Supor(r)-
800, a Nitex filter of 10 pm pore size is mounted and will allow the recovery of 
the intermediate size particles. Another Nitex filter of 50 pm pore size is 
added on the upper part to collect the large particle fraction. This size-
fractionated particulate study is always achieved at 100 m depth for the on 
board 234Th analysis with beta counting. Then, 5 other samples are collected for 
231Pa and 230Th analysis at different depths so as to get a full water column 
profile. The on-board 234Th analysis was further extended during the cruise to 
other depths of the profile, so as to combine both information on the export 
with 234Th and 230Th. The 231Pa, 230Th and 232Th analysis in the 3 size-
fractionated particles requiring clean-lab chemistry and high resolution mass 
spectrometry measurements will be realised at the home laboratory.

The pumping time is ca. 3 hours for most of the deep stations and the entire 
procedure (deployment and recovery) ranges from 5 to 7 hours. In 3 hours about 
400 - 500 L of seawater were typically filtered at very high particle flux 
stations and between 600-800 L at stations with lower biological productivity.

Briefly, once collected on the Nitex filters, the size-fractionated particulate 
material (50 and 10 pm) was recovered by sonication (leaching in ultrasonic bath 
with 100 - 200 ml of 0,2 pm filtered bottom seawater) and the resulting solution 
filtered  through a 47 mm Supor(r)-450 filter. The 47 mm filters, representing 
both size-fractionated particles (50 and 10-50 µm), were then stored in clean 
petri dishes. If any sample has to be counted for 234Th, the 47 mm was dried at 
50°C in the oven and then folded in order to be measured with beta counting. 
Otherwise they were stored wet in the fridge at 4°C. In this latter case, a 
part of the Supor(r)-800 filter (small particles) was cut under clean conditions 
(flow hood in clean container, cleaned material) and punched (with a 22 mm 
diameter punch) to enable a 234Th counting for the small fraction size 
particles. The other part of the Supor(r)-800 filter was folded in half and 
stored in special plastic bags at 4° C.

Tab. 3.3 sums up the particulate sampling, realised with the ISP, during the 
expedition. For stations 131, 161 and 178, the 234Th was counted on the large 
and intermediate size-fractionated particles. At stations 193, 222 (Weddell 
Sea), 230 and 241 (Drake Passage), a part of the Supor(r)-800 filters was cut 
and punched to allow 234Th beta counting for the small particle fraction as 
well. Therefore, at these 4 stations, a full particulate 234Th profile was 
achieved. The major part of the filters was then stored in the special plastic 
bag and frozen.


Tab. 3.3: Summary of the size-fractionated particulate samples (50 µm, 10 µm and 
          0.8 µm) collected with the in-situ pumps from 10.02.08 to 16.04.08. 
          Highlighted in green the 100 m sample for Pinghe Cai. The low filtered 
          volumes (when pumping did not work well) are noted in red*.

Depth (m)   Volume (L)  Depth (m)   Volume (L)  Depth (m)   Volume (L)  Depth (m)   Volume (L)
----------  ----------  ----------  ----------  ----------  ----------  ----------  ----------
13/02/2008              17/02/2008              20/02/2008              24/02/2008
Stn 101                 Stn 104                 Stn 113                 Stn 131
    l00    did not work     100       2831          100       1731          100       2406
    200        358          200    did not work      50        282          250        719
    500        494          500        631          200        453          500        658
    750        537          750       1932          500        547         1000        666
   1000         90*        1250         79*         750        374         2000       1278
   2000        524         2500        517         1000       1352         3800        634

09/03/2008              11/03/2008              18/03/2008
Stn 161                 Stn 178                 Stn 193                 Stn 222
    100        953          100        762          100        840          100        532
    200        416          200        354          200        409          180        271
    440        419          500       1123          500        482          280        481
   1200        596          800        445         1200        631          380        281
   2400        450         1000        321         3200        182*              
   3400        568         1500        425        bottom       503              

02/04/2008              05/04/2008              07/04/2008              07/04/2008
Stn 230                 Stn 236                 Stn 241                 Stn 244
    100        733          100        584          100        336          100        160*
    250       1251          250       1392          120        162*         200        325
    500        417          400        386          750        421          750        499
   1000        636         1000        644         1250        634         1250        702
   2000        440         2800        279         2800       1551         2400        663
   3000        483         3500        397         3300        413         3500        391

11/04/2008
Station 250
    100        378
    150        222
    500        382
    900        606
   2200        466
   3700        368


Sediment

Activities stored in marine sediments can help to reconstruct particle flux 
patterns in the past and surface sediments to evaluate patterns of particle flux 
and boundary scavenging. Therefore, it is a required complementary study to 
investigate the particle dynamics and the winnowing and focusing processes 
occurring on the seafloor in an area submitted to strong currents as the Drake 
Passage.

In this frame, sediment cores were collected with the minicorer (Fig. 3.28) at 
three super stations in the Drake Passage (241, 244 and 250). The minicorer was 
deployed under the normal AWI CTD, 20 m below the CTD frame. The altimeter 
signal gave an estimate of the moment when the minicorer had reached the bottom. 
Enough sediment cores were obtained with the minicorer at Station 241 and were 
sliced and stored in plastic containers. At first sight, it seems that this 
sediment was constituted of clays or silts, with a sandy aspect and overlied by 
numerous Mn crusts (Fig. 3.29).


Fig. 3.28: Minicorer deployment during ANT-XXIV/3 	Fig. 3.29: Mn crust at 
           station 241


Further analyses

In the vicinity of the Antarctic Peninsula, Ra samples, 228Th and further 227Ac 
samples were included in the analyses.

Preliminary results

There are no preliminary results for the 231Pa and 230Th analysis since it 
requires clean-room work and further processes such as mass spectrometric 
techniques that cannot be realised on board and will be done back at the home 
laboratory.

However, the 234Th counting on the particles was achieved on board. Thus, 
Figures 3.30 and 3.31 represent the coarse profiles obtained for the 234Th for 
the large and intermediate size particles at stations 131, 161 and 178 and for 
the total particulate phase at stations 193, 222, 230 and 241.

On Fig. 330, even without the small fraction size particle measurement, a 
"normal" 234Th pattern can be clearly noticed with decreasing particulate 234Th 
with depth at most of the stations, except the maximum observed at station 178 
at 1000 m. Close to the bottom, at stations 222 and 230, the particulate 234Th, 
as expected, increases, likely due to sediment re-suspension.

Moreover, the range of the 234Th particulate concentrations in both fractions is 
in agreement with what can be expected (personal comm. Pinghe Cai) confirming 
that the sonication step efficiently worked.

Fig. 3.31 displays the total particulate 234Th at 4 stations: 193 and 222 in the 
Weddell Sea, 230 and 241 in the Drake Passage. On most of these profiles, the 
characteristic trend of the particulate 234Th can be seen with higher 
concentrations at the surface and near the bottom. To the exception of some 
surface values, all along the water column, the mean total particulate 234Th 
concentrations are ca. 0.05 dpm/L. The maximum values are found at the surface 
and for the station 222 near the Antarctic

Peninsula where the profile follows once more the general pattern with a high 
value near the surface, decreasing with depth and increasing again close to the 
seafloor.


Fig. 3.30: 234Th concentrations (in dpm/L) in 10 and 50 pm combined particle 
           fractions, i.e. for particles >10 pm. The error bars represent a 10 %
           error on the final value.
Fig. 3.31: Total particulate 234Th concentrations (in dpm/L) in all 3 size 
           fractions (L e. particles > 0.8 gm). The error bars represent a 10 %
           error on the final value.



3.3.3  Importance of marine polysaccharides for radionuclides cycling

       Maya Robert Alfred-Wegener-Institut 
       not on board: J. Friedrich, Alfred-Wegener-Institut

Background

Dissolved organic matter (DOM) forms the largest pool of material in 
the marine environment. The colloidal fraction of the DOM is highly 
reactive and thus, plays a large role in biological, physical and 
chemical processes. Due to their high molecular weight, polysaccharides 
belong to the colloidal organic matter (COM). These substances are 
mainly released by marine phytoplankton and bacteria. Some of these 
exopolymers can abiotically aggregate to form particles called 
transparent exopolymer particles (TEP). TEP are very sticky and 
consequently a key controlling factor in vertical fluxes as they glue 
together diverse particles. This occurs via aggregation and leads to 
the formation of large marine aggregates. The sticky nature of TEP is 
linked to the presence of a high fraction of acidic polysaccharides 
with sulphate ester groups, which give the ability to form cations 
bridges and hydrogen bounds, especially with trace elements.

Thorium-234 (234Th), lead-210 (210Pb) and polonium-210 (210Po) are 
produced by radioactive decay of uranium-238 in seawater. 234Th (24 
days half life), 210Po (138 days half life) and 210Pb (22.3 years half 
life) are known for their high affinities to particles and aggregates. 
In seawater these radionuclides occur both in dissolved form and 
adsorbed onto particles. In the COM pool, the polonium (P0) 
distribution differs from thorium (Th) and lead (Pb). Whereas Th and Pb 
seem to have a higher partitioning coefficient in polysaccharide-
enriched COM than in the bulk COM, Po seems to have a much higher 
partitioning coefficient in bulk COM than in polysaccharide-enriched 
COM. This selective complexation points out the importance of the 
chemical composition of marine particles in controlling the scavenging 
of particle reactive radionuclides in particular and trace elements in 
general in the ocean.

Objectives

During the GEOTRACES activities of ANT-XXIV/3 we want to:

1) get a better insight into binding affinities of Th, Pb and Po for 
   polysaccharide-like particles and protein-like particles.
2) Investigate to which extend TEP can play a role in extending 
   210Po as a proxy for particulate organic carbon (POC) transport.

Work at sea

1) At the superstations 210Po and 210Pb have been sampled at different 
depths in the water column (25, 100, 200, 500, 750, 1000 m) on the 
three transects (from CTD rosette Niskin bottles) in 30-40 L samples 
for particulate and dissolved fractions (over 1pm and truly dissolved 
respectively). Additional samples (10-20 L) were used to determine the 
concentrations of TEP and protein-like particles (CSP) in the
particulate and dissolved fractions (filtration over 1 µm then through 
0.4 µm respectively). POC has also been sampled at each depth studied 
(filtration onto precombusted GF/F filters). The filters retaining the 
particulate phase for the radionuclides have been measured on board in 
order to determine the 234Th/238U ratio. Back at the AWI, the same 
filters will be analyzed for 210Pb/210Po determination.

So far, 7 depths profiles can have been sampled.

2) Whenever high volumes of water (ca. 100 L from the chlorophyll 
maximum depth) have been available from the CTD, aggregation 
experiments have been conducted. After determination of the same 
parameters as described above, the seawater is incubated in 5 L 
container that are maintained in rotation (3 rpm) in the dark, at 2°C, 
for different time scale (from 24 h up to 15 days). These experiments 
aim at monitoring the transfer of radionuclides (234Th, 210Po, 210Pb) 
between the dissolved and he particulate fractions and try to correlate 
these changes to those that could be observed for POC, DOC, TEP and /or 
CSP.

So far, 3 aggregation experiments have been conducted.

Preliminary results
All the samples will be later analyzed either in the Geochemie or the 
Biogeochemie groups of the AWL

In Fig. 3.32, the 234Th profiles show different 234Th deficit patterns.


Fig. 3.32: Profile of 234Th in the particulate phase (over 1um) for the 
           200 upper meters N.B.: Errors bars have not been calculated yet. 
           The error can vary from ca. 5 to 10%.



3.3.4  Radium isotopes and 227 Ac

       Ingrid Stimac 
       Alfred-Wegener-Institut 
       not on board: M. Rutgers van der Loeff, C. Hanf land 
       Alfred-Wegener-Institut

Objectives

Four radium isotopes are supplied to the ocean by contact with the 
continent or (deep-sea)-sediments: 223 Ra, (half-life 11.4 d) ; 224 Ra 
(3.7 d), 226 Ra (1620 y) and 228 Ra(5.8 y). The distribution of these 
isotopes in seawater has been shown to be most helpful to evaluate 
shelf-basin exchange and water residence times. On the Greenwich meridian 
we expected extremely low concentrations of all but the longlived 226 Ra. 
We have concentrated the Radium sampling programme in the area around the 
Antarctic Peninsula where Ra isotopes are most informative on shelfwater 
interaction (Hanfland, PhD thesis 2002; Dulaiova, pers. comm.). Like Ra 
isotopes, 227 Ac is released from sea sediments, but its main source is 
in deep-sea sediments. This tracer is therefore especially useful to 
study deep water mixing and ventilation.

Work at sea

Radium

During 13 deployments of in-situ pumps a set of two MnO2 -coated 
polypropylene fiber cartridges was used to adsorb dissolved 
radionuclides. (On station 279 loose MnO2-fiber was used instead to 
allow immediate measurement of 224 Ra with the RaDeCC system, but the 
adsorption efficiency turned out to be unsatisfactory). The 228Ra/226Ra 
isotope ratio will be quantified in the home laboratory by Soxhlet acid 
leaching and subsequent gamma spectroscopy; 226 Ra will be derived from 
the relationship established on earlier expeditions between 226 Ra and 
dissolved silicate.

For the analysis of short-lived radium isotopes, surface water from the 
ship's seawater intake was cartridge-filtered at 31 stations and 
transferred into 250 L tanks in the fishlab. At four shelf stations 
(154, 155, 216, and 221) additional 60-L subsurface samples were 
collected with the Rosette and treated similarly. Each sample was 
pumped at max.1 L/min through Mn02-impregnated acrylic fiber to 
scavenge radium isotopes. Fibers were dried using compressed air, and 
short-lived 223 Ra and 224 Ra measured at-sea using RaDeCC detectors.

Actinium

227 Ac has been sampled in two ways. First, it is collected along with 
radium on the Mn02-coated cartridges during in-situ pump deployments. 
Due to the absence of a second isotope that could serve as yield tracer 
to correct for insufficient absorption of Ac on the fiber, this 
procedure leaves an appreciable uncertainty. The second procedure used 
the discrete approx. 60-L samples from Rosette casts collected in 
cooperation with Torben Stichel for the combined analysis of Hf 
isotopes and 227 Ac (see section on Nd and Hf isotopes). Samples were 
filtered and Hf and Ac were coprecipitated with Fe(OH)3. After return 
to Germany these samples will be separated with ion-exchange procedures 
and analysed in the Kiel and Bremerhaven labs.

Expected Results

From the analysis of radium isotopes we expect to derive signals of 
shelf input which can be related to parallel studies on trace metals 
(Mn, Al: Rob Middag; Fe: Maarten Kiunder) and 232Th (Celia 
Venchiarufti). The 227 Ac data will enlarge the very sparse dataset of 
this isotope. After correction for activity that is supported by 
production from 231Pa in the water column (from the study of Celia 
Venchiarutti) the excess concentrations (227 Ac) will be used to 
estimate upwelling rates of deep water.


3.3.5  Neodymium (Nd) and hafnium (Hf) isotopes

       Torben Stichel 
       IFM-GEOMAR 
       not on board: M. Frank, IFM-GEOMAR

Objectives

The subject of our study is a detailed investigation of the 
distribution of neodymium (Nd) and hafnium (Hf) isotopes in dissolved 
and particulate form in the water column and in the seawater-derived 
fraction of surface sediments of the Atlantic sector of the Southern 
Ocean. Nd isotopes have been shown to be a powerful geochemical tracer 
for present and past water mass mixing and source provenance tracing in 
the ocean. The combination with Hf isotopes was applied successfully 
for the characterization of continental weathering regimes, i.e. it has 
been suggested that coupled Nd-Hf isotope analyses of Hf and Nd allow 
to distinguish weathering regimes dominated by chemical weathering from 
those dominated by physical weathering (van de Flierdt et al., 2002). 
Both isotope systems have been used for the reconstruction of water 
masses in the Southern Ocean on various time scales in the past from 
marine sediments. So far there are, however, nearly no data for the 
water column of the Southern Ocean, which severely restricts the 
reliable application of this combination of tracers for present day 
studies and reconstructions of the past. In the frame of the 
international GEOTRACES programme we collected large volume water 
samples from the surface ocean and from depth profiles at selected 
stations during ANTXXIV/3.


Work at sea

Greenwich meridian

On the Greenwich meridian we have collected 25 samples (8 surface 
samples taken with the towed fish and 17 deep samples by the CTD 
rosette; Tab. 34) with a total volume of about 1500 liters for Nd and 
Hf isotope measurements. The samples were collected under trace metal 
free conditions in acid cleaned 20 liter holding collapsible 
cubitainers. The Hf concentration in seawater ranges from 02 to 1 
pmol/kg and is thus very low (Godfrey et al., 1996; McKelvey and 
Orians, 1998). For meaningful Hf isotope measurements on a multi 
collector inductively coupled mass spectrometer (MC-ICPMS) in the home 
laboratory, Hf from at least 50-60 liters (5-10 nanograms Hf) were 
needed for each sample taken below 100-200 meter. Due to the even lower
Hf concentration in the surface waters, samples taken by the towed fish, 
had to be even larger (100-120 liters). After collection, the samples were 
filtered through a filter of 0.45 pm mesh width, which was kept for later 
particle analysis. In order to avoid adsorption of Nd and Hf onto the walls 
of the cubitainers, the samples were acidified to pH 2 by addition of double 
distilled concentrated acid. For every large volume sample we filtered, 
acidified, and stored a 2 liter aliquot to determine the concentration of Nd 
and Hf by isotope dilution in the home lab. To the rest of each sample 05 ml 
of a FeCI3 solution containing 200 mg Fe per ml were added to each 20 liter 
sample. After this step the pH was titrated back to 7-8 by addition of a 
suprapure ammonia solution to co-precipitate FeOOH, which scavenged the 
dissolved trace metals in the sample. After 24-48 h most of the supernatant 
was discarded. Afterwards the samples were transferred into 2 liter acid 
cleaned wide mouth bottles. Additionally, at each Super Station shared 20 
liter samples were taken for Nd, thorium (Th), and protactinium (Pa) 
isotope measurements (see subsection 3.32) to have a total of 59 Nd samples 
inclusive duplicates.


Tab. 3.4: List of samples from hydro-casts (a) and surface waters (b) 
          with corresponding depths in meters for each station.

a)
   Stat.:    71/101       71/104      71/131     71/161     71/181
   LAT:    42°20.3'S    47°39.3'S    58°59'S    66°30'S    69°36'S
   LONG:    8°59.6'E     4°16.2'E      0°E        0°E        0°E
   ---------------------------------------------------------------
              750          400         400        440       1465
                           750         900        800
                          1200        1500       1200
                          2000        2500       2400
                          4500        4070       3400
b)
   Stat:       I           II         71/105       71/116      71/133       
   LAT:    34°53.1'S    38°38'S      47°39.3'S    54°21'S    59°14.4'S
   LONG:   16°40.7'E    11°35.8'E    4°16.16'E     0°01'E     0°02.9'E

b) continued
   Stat:     71/142     71/151    GvN-Fish     71/156
   LAT:     62°20'S    65°19'S    68°31.8'S    67°08'S
   LONG:     0°E         0°E       4°39'W       0°24'E


Weddell Sea and Drake Passage

On the transect from Neumayer Station (Atka Bay, Antarctica) to Punta 
Arenas (Chile) a total of 39 water samples for Hf and Nd analyses were 
collected in the Weddell Sea and the Drake Passage. 12 of these samples 
were taken from surface waters and 27 samples from hydro cast CTD 
profiles (Tab. 3.5). In addition, 50 shared samples in total were taken 
for Nd, Th and Pa isotope measurements on all Super Stations (see 
subsection 3.32).


Tab. 3.5: List of samples from hydro-casts (a) and surface samples (b) 
          recovered in the Weddell Sea and the Drake Passage with 
          corresponding depths in meters.
a)
   Stat.:   71/193      71/222      71/236      71/241      71/250
   LAT:     66°36'S     63°21'S     59°00'S     57°38'S     55°45'S
   LONG:    27°17'W     52°51'W     58°09'W     60°53'W     64°26'W
   ----------------------------------------------------------------
              500         450         500         480         500
             1200                    1000         750         900
             2200                    1500        1250        1600
             3200                    2500        2800        2500
             4800                    3700        3550        3800

b)
   Stat.:    III      71/186     71/191       IV          V         VI
   LAT:    60°02'S    69°03'S    67°21'S    65°34'S    64°59'S    64°20'S
   LONG:   15°42'W    17°25'W    23°38'W    36°46'W    42°00'W    46°04'W

   Stat:    71/210    71/222       VII      71/223      VIII       71/244
   LAT:    64°03'S    63°21'S    62°08'S    63°17'S    60°03'S    56°53'S
   LONG:   48°15'W    52°51'W    57°31'W    53°14'W    55°24'W    62°31'W


Expected results and further processing

We will determine the isotope composition of Nd and, for the first time 
of Hf, in both dissolved and particulate form to characterize the 
isotopic composition of the different Southern Ocean water masses, 
their sources, and mixing relationships. This will enable new insights 
into the influence of weathering processes of the Antarctic continental 
landmass on the geochemical composition of the Southern Ocean, as well 
as a detailed isotopic characterization of the water masses prevailing 
in the Atlantic sector of the Southern Ocean and the Weddell Sea. The 
new data will allow a more reliable application of the Nd/Hf isotope 
systems for reconstructions of past weathering regimes and ocean 
circulation.

In the home laboratory, the FeOOH precipitates of the samples will be 
centrifuged and separated from the remaining supernatant. To remove 
most of the organic matrix, the samples will be treated with aqua regia 
after drying. The next step will be the separation of the Hf and Nd 
from Fe of the FeOOH-precipitate, which will either be carried out by 
backextraction* or large volume (40 ml resin) cation separation 
columns. "Hf" and "Nd" cuts will then be collected separately. The "Nd" 
cuts will be further purified through additional cation column steps to 
separate the REEs from Ba and achieve a pure rare-earth-element (REE) cut. 
To separate Nd from other REEs, a Ln-SPEC resin will be used. The "Hf" cut
 will be further purified by a one step column chemistry modified after 
(Münker et al., 2001). The isotopic composition will then be measured on 
a Nu-Instruments multi-collector-inductively coupled plasma mass spectrometer 
(MC-ICPMS). For the measurements of the Nd and Hf concentrations of each 
sample, a Nd and Hf spike will be added to each 2 L aliquot to determine the 
concentrations by the isotope dilution method on the MC-ICPMS.

*: Trace elements, which are adsorbed on the FeOOH-precipitate, are 
dissolved in 6M HCI together with the precipitate. Iron forms a HFeCI4-
complex which is taken up by di-ethylether (Nachtrieb and Conway, 1948; 
Nachtrieb and Fryxell, 1948). The residual trace elements stay in the 
aqueous solution and can be separated.


References

Godfrey, L.V., White, W.M. and Salters, V.J.M., 1996. Dissolved 
    zirconium and hafnium distributions across a shelf break in the 
    northeastern Atlantic Ocean. Geochimica et Cosmochimica Acta, 60(21): 
    3995-4006.
McKelvey, B.A. and Orians, K.J., 1998. The determination of dissolved 
    zirconium and hafnium from seawater using isotope dilution inductively 
    coupled plasma mass spectrometry. Marine Chemistry, 60(3-4): 245-255.
Münker, C., Weyer, S., Scherer, E. and Mezger, K., 2001. Separation of 
    high field strength elements (Nb, Ta, Zr, Hf) and Lu from rock samples 
    for MC-ICPMS measurements. GEOCHEMISTRY, GEOPHYSICS, GEOSYSTEMS, 2.
Nachtrieb, N.H. and Conway, J.G., 1948. The Extraction of Ferric 
    Chloride by Isopropyl Ether. I. J. Am. Chem. Soc., 70(11): 3547-3552.
Nachtrieb, N.H. and Fryxell, RE., 1948. The Extraction of Ferric 
    Chloride by Isopropyl Ether. II. J. Am. Chem. Soc., 70(11): 3552-3557.
van de Flierdt, 1., Frank, M., Lee, D.-C. and Halliday, AN., 2002. 
    Glacial weathering and the hafnium isotope composition of seawater. 
    Earth and Planetary Science Letters, 201(3-4): 639-647.



3.3.6  Rare earth elements and barium

       Ingrid Stimac 
       Alfred-Wegener-Institut 
       not on board: M. Rutgers van der Loeff, Alfred-Wegener-Institut

Objectives

The varying REE-pattern is transferred to the ocean via processes such 
as riverine inputs, dust inputs, or leaching of shelf sediments and ice
drifted sediments. In addition to selective weathering, elemental 
fractionation may also occur during aqueous transport, where natural 
particles and colloids are of great importance. The REE concentrations 
coupled with the Nd isotopic ratios (subproject 3.3.5) are powerful tracers 
to investigate scavenging processes and to predict the fate of elements 
brought from the continent. The REE's residence times on the order of 1000
years make them ideal tracers for water masses as it allows for long 
distance transport while preventing complete homogenisation.

The geochemistry of barium is closely linked to that of radium. For the 
interpretation of our measurements of radium it is important to know 
the barium and silicate as well.

Work at sea

Samples were collected for REE in dissolved and particulate form. For 
dissolved REE 1 L of seawater was collected in surface waters and at 
deep stations using the NIOZ Titanium-Rosette. Such samples were 
obtained at all superstations along with the sampling for 231Pa and 
230Th and barium.

Particulate REE in surface waters has been collected by the ship's 
seawater pump and a continuous flow centrifuge. At each superstation, 
2,500 - 5,800 L of seawater was centrifuged at a rate of about 500 - 
1,000 L per hour at 16,000 g. The combined centrifugate, a brown-green 
paste with a high content of phytoplankton and sea-salt, was stored 
frozen. It will be freeze dried and analyzed for its elemental 
composition at AWL



3.3.7  Iron isotopic fractionation near the Antarctic Peninsula

       Patrick Laan, C. Thuroczy, Cornelis van Slooten, Hein de Baar
       NIOZ
       not on board: M. Staubwasser (University Köln), M. Rutgers van der 
       Loeff, D. Abele Alfred-Wegener-Institut

Objectives

On the occasion of approaching the Antarctic Peninsula towards Jubany 
the objective is to collect seawater samples to complement the IPY 
project CIicOPEN (Doris Abele; Eol#1 93; full proposal #34) on the 
issue of iron stress on near-shore ecosystems of the Antarctic 
Peninsula. Briefly it is planned to assess the ratio of stable isotopes 
of iron (Fe) to link the high coastal Fe concentrations with semi 
continuous surfacewater profiles to the growth-limiting concentrations 
far offshore. Such a transect is especially interesting for studies of 
Fe isotopic composition, which can be measured at far better precision 
at these elevated concentrations and thus will allow to identify any 
isotope fractionation during early Fe uptake. Samples for Fe isotopic 
composition studies are to be collected (cooperation with Michael 
Staubwasser, University Köln).

Work at sea

We have done five shallow casts with the ultraclean Rosette, at overall 
five stations on the approach towards the Antarctic Peninsula. At three 
to five depth horizons samples of 20 to 50 liters were collected for 
iron isotope analysis. The seawater samples were all filtered, some on 
membrane filters, others over a filter cartridge (0.2 micron Sartorius 
Sartobran 300). Moreover filtrations have been done in another approach 
over a suite of two filter membranes of 5 micron and 045 micron nominal 
size cutoff respectively, placed in-line such that the first 5 micron 
filter takes out the larger size class marine particles, and next the 
finer 045 micron filter removes the smaller size class particles. The 
membrane filters were stored in the freezer for isotope analyses as well. 
In parallel for selected stations and selected depths the distribution of 
dissolved trace metals Fe, Mn and Al was sampled, and analyzed in context 
of projects 3.1.1. and 3.1.3, respectively. For exact information on 
sampling, filtrations and ancilliary samples for Fe, Mn Al, see the Excel 
sheet of each station hydrocast Gi to G5.



3.3.8  δ 13C of particulate organic material in the Southern Ocean

       Elisabeth Sweet 
       Alfred-Wegener-Institut 
       not on board: D. Wolf-Glad row, U. Passow, C. De La Rocha, 
       Alfred-Wegener-Institut

Objectives

The Southern Ocean may have been essential for the drawdown of 
atmospheric CO2 during glacial periods. In order to reconstruct the 
state of the Southern Ocean during glacial periods and the processes 
responsible for altered states various paleo-proxies including δ13C(org), 
δ15N, δ°30Si, have been proposed and applied. A major problem for the 
application of δ13C(org), as a paleo-proxy is its large variation in the 
Southern Ocean and the unknown origin of isotopically very light 
organic material (δ13C(org) below -30%). Our goal is to identify the 
phytoplankton species responsible for this light material, to look for 
variations under various growth conditions, and to investigate the 
relationships between δ13C(org) to other paleo-proxies based on 
consistent data sets. The work will contribute to the international 
programme GEOTRACES (2006).

Work at sea
Samples containing in-situ phytoplankton were collected from the 
chlorophyll maximum at 5 stations and 6 super stations on the Greenwich 
meridian transect. The depth of the mixed layer was determined based on 
the CTD profile and where no clear chlorophyll maximum peak was 
present, a depth of 50 m was used as a standard depth.

In order to separate different plankton groups the suspended 
particulate material was fractionated sequentially into 5 size classes: 
0.2 - 1.2 µm, 1.2 - 5 µm, 5 - 20 µm, 20 100 µm and > 100 µm. The 
particulate material collected from each size fraction was resuspended 
immediately after sampling in 0.2 µm filtered sea water from the 
previous station, by rigorous shaking in a glass bottle in a similar 
procedure as that suggested by Rau et al. (1999). To evaluate the 
collected species composition and further characterize the particulate 
material sampled 20 ml of the suspension were transferred into a 25 ml 
screw capped scintival and chemically fixed for later microscopic 
investigation. The remaining suspension was filtered through a 
precombusted glass fibre filter (GF/F 25 mm diameter) for the four 
larger size fractions and through a precombusted silver filter (25 mm 
diameter) for the 0.2 pm size fraction. These filters were frozen for 
isotopic analysis, which will be conducted at the Alfred Wegener 
Institute.

The large diatoms (Corethron sp., Fragilariopsis kerguelensis) common 
in the Southern Ocean will be collected in the > 100 µm fraction, 
whereas the smaller diatoms like Pseudonitzschia sp. and many protozoa 
will be collected in the 20 - 100 µm fraction. Copepods caught in the 
large size fractions will be hand picked off the filters. Flagellates 
of Phaeocystis antarctica and other flagellates will dominate the 5 - 20 
µm fraction. Bacterio-plankton (0.2 -1.2 µm) and picoplankton (1.2 - 5 
µm) will dominate the two respective smallest fractions.

A minimum of 50 - 80 µg of carbon per filter is required for the 
measurement of δ13C(org). At a chlorophyll concentration of 0.5-2 µg L(^-1) 
and a carbon: chlorophyll ratio of 40 g g(^-1) filtration of 20 to 40 L of 
seawater will collect enough material for δ13C(org) measurements of 
samples fractionated into 5 size classes. This has been confirmed by 
measurements performed within an earlier fractionation experiment. The 
amount of water filtered was determined at each station according to 
the chlorophyll concentration, which is measured online as fluorescence 
and the amount of particulate material present in the sample during 
filtration. Smaller volumes of water were required for filtration 
through the smaller size fractions.

Preliminary results

Isotopically extremely light values (δ13C(org) < -28 ‰) were consistently 
observed at stations south of the Polar Front, with values δ13C(org) < -30 ‰ 
in at least one size fraction at 4 stations. The fractionations εp indicate 
that the produced organic carbon was appreciably lighter (+ 14 to 20 ‰) than 
the source DIC implying that biology is a key factor responsible for the 
isotope ratios.



3.3.9  Mapping the distribution of Si isotopes in Southern Ocean waters

       Elisabeth Sweet 
       Alfred-Wegener-Institut 
       not on board C. L. De La Rocha, Alfred-Wegener-Institut

Objectives

The Silicon isotopic composition of sedimentary diatoms is a key proxy 
for reconstructing nutrient cycling in the Southern Ocean and its 
impact on atmospheric CO2 over past climate cycles. It is considered to 
reflect the extent to which the nutrient, silicic acid, is removed from 
the euphotic zone in support of primary production. The extent of CO2 
uptake during primary production relative to the upwelling of CO2-rich 
deep waters in the Southern Ocean, in turn, has a strong influence on 
atmospheric concentrations of CO2.

To date paleoceanographic reconstructions of silicic acid draw down in 
the Southern Ocean, south of the present day Antarctic Polar Front 
(APF), has produced conflicting results with that of nitrate draw down. 
The Si isotopic composition of diatoms has suggested that silicic acid 
is more completely consumed during interglacials, and is utilized to a 
significantly lesser extent during glacials, especially the last 
glacial maximum (LGM) and the maximum of the penultimate glacial cycle. 
The nitrogen isotopic composition of organic matter trapped within the 
siliceous framework of diatoms, however, suggests the opposite pattern 
for nitrate utilization.

The objective of this work is to map both the distribution of Si 
isotopes in dissolved nutrients in surface waters in the Southern 
Ocean, providing information as to the range and variability of the 
variations (especially of the isotopic composition of nutrients) over a 
fine spatial scale and to examine the Si and composition of seawater 
and diatoms in the Southern Ocean.

Work at sea

Samples were collected at 4 stations on the Greenwich meridian transect 
and 2 on the Weddell Sea transect. 16 depths per cast were sampled to 
construct a complete depth profile on these stations from depths 
ranging from 10 meters at the shallowest down to 5000 meters at the 
deepest (although most sites were shallower than this). At Station 
PS71/115-2 a reduced 7 depth profile was sampled to enable an 
intercalibration with the Marion Dufresne:

Once the samples were collected the water was filtered throught 0.6 pm 
polycarbonate filters to obtain biogenic (BSi) and lithogenic (LSi) 
silica concentrations; and δ30Si of dissolved silicon. The parameters 
sampled for will be measured back at the AWL

Preliminary results

70 depths were sampled from 6 different CTD casts on the first part of 
the cruise ANT-XXIV/3. These samples fall along a cruise track that 
covered temperate to polar regimes, crossed over the Antarctic 
Divergence, the Antarctic Polar Front, and the Subantarctic Front, 
regions of low Fe availability as well as those (down wind of land 
masses or on the Kerguelen Plateau) where Fe may be abundant, and both 
open and coastal waters. The samples taken should allow for 
documentation of shifts in isotope values over a broad range of 
conditions. This will help us to improve Si isotope-based 
paleoceanographic reconstructions of nutrient utilization and CO2 
removal. The data sets produced, in addition to enhancing our 
understanding of a proxy fundamental to reconstructions of Southern 
Ocean paleoceanography, falls under the auspices of the IPY umbrella 
project, BIPOMAC, and will also contribute to the trace metal and 
isotope mapping efforts of GEOTRACES.



3.3.10  Uranium isotopes

        Ingrid Stimac(1), Hein de Baar(2)   (1)AIfred-Wegener-Institut
        not on board: B. Moran(3),          (2)NIOZ
        M. Rutgers van der Loeff(1)         (3)University of Rhode Island

Objectives

New methods are now available for more accurate determination of the 
isotopic composition of uranium (U) in seawater. This allows better 
insight in the geochemistry of U in the oceans. One important aspect is 
to be able to distinguish the U isotopic signal of different water 
masses.

Work at sea

In an effort to capture the core water masses of Antartic Intermediate 
Water (AAIW), the underlying water of North Atlantic Deep Water origin, 
and the Antarctic Bottom Water, 10 samples of 4 L each have been 
collected at a station situated north of the Polar Front, as to be able 
to sample AAIW which forms at the Polar Front, and does not exist South 
of the Polar Front. The station positioned at 44°39.69'S, 7°5.59'E (PS71-
102-2 at 15.02.2008) was sampled at depths of 300, 400, 500, 750, 1,000, 
1,500, 2,000, 2,500, 4,000 and 4,500 m. Each sample was acidified with 
1 ml/liter of Seastar 12M HCI baseline grade (this acid was available 
in context of project 3.15. on Cd isotopes) and then stored for future 
analysis by Brad Moran.



3.4  Nutrient measurements during ANT-XXIV/3

     Jan van Ooijen
     NIOZ

Background

On this cruise samples were analysed on phosphate, silicate, nitrate 
and nitrite.

At the end of the cruise there will be about 18,000 analysis (4,500 
samples) accomplished on a Bran and Luebbe Traacs800 Autoanalyser 
connected to an autosampler. The different nutrients were determined 
colorimetrical as described by Grashoff (1983).

Methods

Samples were obtained from a CTD rosette sampler, an ultraclean CTD and 
of algae growth experiments. All samples were obtained in a 
polyethylene vial and the samples of the algae growth experiment were 
filtered over a 020 pm acrodisc filter. They were all stored dark at 
4°C. CTD samples were analysed within 12 hours all other samples within 
24 hours on a Technicon TrAAcs 800 autoanalyzer.

Standards were prepared fresh every day by diluting the stock solutions 
of the different nutrients in nutrient depleted surface ocean water. 
This water is also used as baseline water. Each run of the system ha,d 
a correlation coefficient for 9 calibrant points of at least 0.9999. 
The samples were measured from the lowest to the highest concentration 
in order to keep the carry over effects as small as possible.

In every run a mixed nutrient standard containing silicate, phosphate 
and nitrate in a constant and well known concentration, a so called 
antarctic nutrient-cocktail, was measured in duplicate. This cocktail 
is used as a guide to check the performance of the analysis and used to 
make a correction at the end of a transect obtaining the final data.

Over the last 20 years this cocktail has proven to be stable for at 
least 10 years and has also been used and monitored in many 
intercomparisment tests (ICES, Quasimeme). The reduction efficiency of 
the cadmium column on the NO manifold was as least 97 % and measured in 
each run.

Chemistry

Silicate reacts with ammoniummolybdate to a yellow complex, after 
reduction with ascorbic acid the obtained blue silica-molybdenum 
complex was measured at 800 nm. Oxalic acid was used to prevent 
formation of the blue phosphatemolybdenum.

Phosphate reacts with ammoniummolybdate at pH 1.0, and 
potassiumantimonyltartrate was used as an inhibitor. The yellow 
phosphate-molybdenum complex was reduced by ascorbic acid and measured 
at 880 nm.

Nitrate plus nitrite (NOx) was mixed with a buffer imidazol at pH 7.5 
and reduced by a copperized cadmium column to nitrite. This was 
diazotated with sulphanylamide and naphtylethylenediamine to a pink 
colored complex and measured at 550 nm.

After subtracting the nitrite value of the nitrite channel the nitrate 
value was achieved.

Nitrite was diazotated with sulphanylamide and naphtylethylenediamine 
to a pink colored complex and measured at 550 nm.

Statistics after corrections for the Greenwich meridian transect
The standard deviation of reference material within a run:


P04: 0.006 uM  0.16% of full scale value 
Si:  0.084 uM  0.06% of full scale value 
NOx: 0.063 uM  0.13% of full scale value 
NO2: 0.001 uM  0.05% of full scale value

The standard deviation of reference material between the runs are:

P04: 0.009 uM  0.27% of full scale value
Si:  0.464 uM  0.33% of full scale value
N0:  0.222 uM  0.24% of full scale value
NO2: 0.006 uM  0.39% of full scale value

Suspicious bottles

Bottles which seem not to have closed at the right depth at the 
Greenwich meredian transect are:

CTD 106-1-1
CTD 127-1-2
CTD 134-1-4 or CTD 134-1-1

Preliminary results

An overlook of the results of the nutrient analysis on the Greenwich 
meridian transect is plotted in ODV (Fig. 333).


Fig. 3.33: Vertical transects of SI and NO along the Greenwich meridian



3.5  Silicate measurements with cyclic voltammetry

     Marielle Lacombe and Veronique Garcon CNRS/LEGOS

Background and General Objectives

Real time, long-term in-situ monitoring of the ocean, leading to the 
acquisition of repeated measurements without having a ship at sea 
permanently, constitutes a crucial step to increase our knowledge of 
the ocean. Chemicals in the ocean play an essential role and 
particularly nutrients controlling photosynthesis. Electrochemistry 
seems a well adapted method for in-situ measuring of bioactive 
components in extreme conditions found in the ocean. The potentialities 
of the voltammetric methods for the analysis of various chemical 
species in the marine environment have already been demonstrated. They 
allow to measure several species simultaneously and this down to very 
low concentrations and without reagent (Luther et al., 2007). Moreover, 
microelectrode techniques are particularly adapted to high pressure 
environments. In this context, we developed a new method for silicate 
determination in the ocean using no reagent (Lacombe et al., 2008). 
Silicates are non-electroactive species. The method involves complexing 
molybdenum salt in acidic medium with silicate to make it 
electroactive. This method was compared during Drake ANT-XXIIII3 Cruise 
(Polarstern, PI C. Provost) with the classical colorimetric one in 
Drake Passage, and showed excellent results (Lacombe et al., 2007). The 
variability of the different water masses of this key passage was also 
studied using hydrographic parameters.

The Drake Passage is an important entry point for several water masses 
from the Pacific into the Atlantic Ocean. They are carried by the 
Antarctic Circumpolar Current (ACC) around the Antarctic continent and 
thus can enter in the South Atlantic and the Weddell Sea. Our objective 
is to compare the present picture of water mass mixing with that of the 
Drake Cruise in 2006 (ANT-XXIIII3), and in particular the SPDW (South 
Pacific Deep Waters) spreading. We will also document water mass mixing 
along the Greenwich meridian.

Work at sea

We sampled for silicate determination along Greenwich meridian-Drake 
transects (along the Greenwich meridian and in the Weddell Sea). The 
samples were analyzed on board by cyclic voltammetry with a glassy 
carbon electrode, with an Ag/AgCI reference electrode and a carbon 
counter electrode. The detection method was developed on new working 
electrodes to avoid the manual polishing that is required with the 
glassy carbon one for a complete autonomous measurement. 
Electrochemical measurements were carried out with a Metrohm 
potentiostat and with a newly developed autonomous submersible 
potentiostat.

Preliminary results

The new electrochemical detection method was developed and tested on 
board on gold and platinum electrodes during the Greenwich meridian 
transect, and the Weddell Sea section allowed us to test the stability 
of the response. The oxide
formed at the electrode surface appears not to be very stable and more 
experiments are needed to yield a fully satisfying method. The 
autonomous submersible potentiostat had electronic problems and was out 
of use. One of the mains problem encountered was the leaking of the 
measurement cell. This problem will be easily solved back in the 
laboratory.

The profiles obtained will be compared with the classical silicate 
determination carried out by colorimetry by the NIOZ team along the 
Weddell Sea transect. The study of the stability of the measurements 
will allow us to conclude on the potentialities to adapt this new 
method on a autonomous in-situ sensor.
The distribution of silicate concentrations will document the different 
water masses along the Greenwich meridian and in the Weddell Sea.


References

Lacombe M., Garcon V., Comtat M., Oriol L., Sudre J., Thouron D., 
    LeBris N., Provost C., 2007. Silicate determination in sea water: 
    toward a reagentless electrochemical method. Marine Chemistry. 106, 
    489-497.
Lacombe M., Garcon V., Thouron D., Le Bris N., Comtat M., 2008. A new 
    electrochemical reagentless method for silicate measurement in 
    seawater. Talanta. submitted.
Luther G.W., Glazer B.T., Ma S., Trouwborst RE., Moore IS., Metzger E., 
    Kraiya C., Waite T.J., Druschel G., Sundby B., Taillefert M., Nuzzio 
    D.B., Shank TM., Lewis B.L., Brendel P.J., 2008. Use of voltammetric 
    solid-state (micro) electrodes for studying biogeochemical processes: 
    Laboratory measurements to real time measurements with an in-situ 
    electrochemical analyzer (ISEA). Marine Chemistry. In Press, -.



3.6  Intercomparison of GEOTRACES variables with BONUS-GOODHOPE

     Hein de Baar(2), Patrick Laan(2),           (1)Alfred-Wegener-Institut
     Elisabeth Sweet(1), Celia Venchiarutti(1),  (2)NIOZ
     Ingrid Stimac(1),	
     not on board: M. Rutgers van der Loeff(1),  (3)LEMAR, CNRS-UMR
     C. de la Rocha(1)                           (4)Vrije Universiteit Brussel
     On board Marion Dufresne: Marie Boye(3),    (5)Royal Museum for Central Africa
     Frank Dehairs4, Matth ieu Roy-Barman(6)     (6)CNRS
     Damien Cardinal(5),	
     not on board: C. Jeandel


For the sections from Cape Town to the Greenwich meridian, and from 
there along Greenwich meridian to Antarctica, the CASO-GEOTRACES 
programme of Polarstern ANT-XXIV/3 was complementary to the BONUS-
GOODHOPE programme aboard Marion Dufresne. Towards an overall 
integrated database of both expeditions, some intercomparison between 
both programmes had been envisioned.

Before departure from Cape Town, where Marion Dufresne was also in 
port, there had been a meeting on board Polarstern for organizing the 
intercom parison. This had to be modest for following reasons:

- departure of both vessels from Cape Town was delayed with many days for 
  various reasons, at expense of scientific stations time,
- adverse weather conditions in the Southern Ocean caused more time losses, 
- the extensive research objectives of both expeditions were very ambitious, 
- the number of pre-cleaned sample bottles on board both ships was limited.

The agreed strategy was twofold. Firstly the initial cruise tracks of 
Polarstern and Marione Dufresne had been scheduled to be overlapping, and 
that, in principle, allowed the positioning of stations and sampling depths 
at the same place. That was the strategy of choice for intercomparison of 
CO2 system measurements, see further section 43, and for major 
nutrients. Secondly for a limited number of variables, it had been 
decided that both ships would take a small number of duplicate samples 
to be exchanged after the expeditions were completed, for final 
analyses at the home laboratories. These variables are barium, 
dissolved trace metals, neodymium I thorium-Isotopes I protactinium 
(NdfTh/Pa), and silicon isotopes.

Once at sea, Polarstern, due to its earlier departure, was further south than 
Marion Dufresne. On 26 February the positions and sampling depths of 
Polarstern stations completed up to then (then until 59°S, 0°W) were 
communicated to Marion Dufresne to allow their re-occupation of selected 
mutual stations, their overall research programme, weather permitting.

Moreover 12 duplicate samples (Ingrid Stimac) for barium at 46°S, 5°53'E 
(PS71103-1 at 16.02.2008) were collected on Polarstern, 10 duplicate 
filtered seawater samples (Patrick Laan) for trace metals at 47°40 5 
4O.7l E (PS71-104-2 at 16.02.2008); 3 duplicate samples (Celia 
Venchiarufti) for Nd/Th/Pa at 52°59.58S 0°2.39E (PS71/113-4 at 
20.02.08); and 7 duplicates (Elizabeth Sweet) for Si isotopes at 53°31'S, 
0°0.30'E (PS71-115-2 at 21.02.2008).

Similarly the BONUS-GOODHOPE team aboard Marion Dufresne collected 
several replicate samples (Marie Boye) for trace metals at 10 depths at 
43°33.16' S, 4°22.36'E (their station GF-19 cast S3 on 04.03.2008), and 
3 replicate samples (Matthieu Roy-Barman) for Nd/Th/Pa at 52°59'S, 0°E. 
Damien Cardinal agreed to take replicates for Si isotopes at same 
location as above for such replicates taken on Polarstern, actual 
sampling yet to be confirmed.




4.  DISSOLVED CARBON DIOXIDE IN THE SOUTHERN OCEAN

4.1  Deep-ocean carbondioxide chemistry (DIC, TAlk)

     Steven van Heuven(1),(2), Hans Slagter(1),(2)   (1)NIOZ
     not on board: H. Zemmelink(1),                  (2)University of Groningen
     M. Hoppema(3)                                   (3)AWI

Objectives

In the last 250 years large amounts of CO2 have been emitted to the 
atmosphere as a result of human activity. A significant fraction (50%) 
of this 'anthropogenic CO2 has subsequently been taken up by the 
oceans, which by doing so, are having a dampening effect on the speed 
of the climate change predicted to result from the increasing 
atmospheric CO2 concentration.

The total amount of anthropogenic CO2 taken up, current and past rates 
of uptake, the potential decline in uptake due to saturation of the 
surface ocean and the deleterious effect on marine life resulting from 
the acidification associated with the increasing amount of dissolved 
inorganic carbon (DIC) of the oceans are current focusing points of the 
fields of marine chemistry, biogeochemistry and biology.

Next to laboratory and field studies aimed at conceptual and 
mechanistic understanding of the many processes involved, a large 
effort is being made to investigate the state of the carbonate system 
in the world's oceans. This is performed almost exclusively through 
research cruises since no remote sensing or automated profiling systems 
are currently available for this task.

In order to be able to calculate the exact state of the carbonate 
system (i.e., the precise concentrations of all substances constituting 
DIC), one additional of the four measurable parameters of the carbonate 
system (pH, pCO2, DIC, total alkalinity) must be determined. The setup 
that was used here measures TAlk and DIC of each sample simultaneously.

Work at sea

High-precision measurements were made of the dissolved inorganic carbon 
(DIC) content and total alkalinity (TAlk) of samples collected at 126 
oceanographic stations. This yielded at total of 2,400 unique samples 
of which a subset (400) was analyzed on both machines to allow for 
intercalibration.

Analysis of DIC was performed using the coulometric method (Johnson et 
al., 1993; DOE, 1994). TAlk analysis was carried out with acid 
titration (Gran, 1952; Bradshaw et al., 1981; DOE, 1994). Both analyses 
were performed using a single integrated system: the VINDTA (Versatile 
Instrument for Determination of Titration Alkalinity; MARIANDA: Marine 
Analytics and Data, Kiel, Germany). Drift control and accuracy of the 
analyses were maintained through extensive use of labstandards and 
certified reference material (CRM, supplied by Dr. A. Dickson, Scripps 
Institution of Oceanography).

Technical details on methods used

Two VINDTA setups were used concurrently, often running a sample 
'together' drawing from the same sample bottle at the same moment. 
These 'duplicates' are used to ensure system intercomparability.

As to the determination of DIC by coulometry: a precisely known amount 
of sample (20 ml) is dispensed from an automated, thermostated pipette 
into a stripper. The sample is acidified here, converting the two 
carbonate species into dissolved CO2(aq). The evolving CO2 is rapidly 
removed from the sample by sparging with N2. The CO2-enriched N2 stream 
is led through the solution in the coulometric cell, which absorbs the 
CO2 and becomes more transparent. The coulometer subsequently 
electrically titrates the solution back to its original opacity. The 
required amount of charge is a linear measure of the amount of CO2 
absorbed.

Total alkalinity is mathematically derived from a titration curve, 
fitted in an electrochemically consistent manner along data of 
electrode potential derived from an acid-titration of an accurately 
known amount of sample (100 ml), dispensed with an automated, 
thermostated pipette. Titration is performed in a thermostated cell. 
With knowlegde of the sample's volume and density, the concentrations 
of the DIC and total alkalinity in the sample are easily calculated.

Samples, collected without headspace in 600 ml Duran bottles, where 
brought to analysis temperature (25°C) by flowing through a heat 
exchanger on their way from the sample bottle to the VINDTAs. Samples 
were injected into the system under a slight overpressure (0.4 bar), 
which fully suppressed the bubble formation often associated with the 
drawing of sample into the VINDTA using a peristaltic pump.

Lab standard was prepared on board in batches of 60 L by filtering and 
poisoning water collected with the CTD from around 2,000 m deep, or 
simply from the ship's surface water tap. For the later batches, the 
pCO2 of the batch was, prior to use, brought to 1.4 times the 
atmospheric value (thus 550 patm) by sparging, so that upon headspace 
pressurization no significant CO2 exchange with the lab standard 
headspace would occur. The sparging process was monitored with a LiCor 
7000 infrared gas analyzer.

Approximately every 5th analysis was followed by analysis of this 
labstandard, and CRM was analyzed 3 or 4 times per day in order to set 
accuracy and to detect and be able to correct for measurement drift. 
Every CRM-sample was run on both machines at the same time. A definitive 
way of application of corrections is still to be decided upon.

Measurements were performed in a thermostated container, with the 
components most sensitive to sudden temperature drops (caused by the 
turning on of the air conditioning unit), being thermally insulated in 
order to smooth out those peaks.

Examples of the obtained data are displayed in figures 4.1 and 4.2.


References

Bradshaw, A.L., Brewer, P.G., Shafer, D.K., Williams, R.T., 1981. 
    Measurements of total carbon dioxide and alkalinity by potentiometric 
    titration in the GEOSECS programme. Earth and Planetary Science Letters 
    55, 99-115.
DOE, 1994. Handbook of methods for the analysis of the various 
    parameters of the carbon dioxide system in sea water. Version 2, A. G. 
    Dickson & C. Goyet, eds. ORNL/CDIAC-74
Gran, G., 1952. Determination of the equivalence point in potentiometric 
    titrations. Analyst, 77, 661-671.
Johnson, KM., Wills, K.D., Butler, D.B., Johnson, W.K., Wong, CS., 
    1993. Coulometric total carbon dioxide analysis for marine studies: 
    maximizing the performance of an automated gas extraction system and 
    coulometric detector. Marine Chemistry, 44, 167-187.


Fig. 4.1: Preliminary results for the section along the Greenwich meridian for 
          DIC. These data are quite close to being final.
Fig. 4.2: Preliminary results for the section along the Greenwich meridian for 
          TAlk. Please note that additional correction of these data has yet to 
          be performed.



4.2  Surface water carbondioxide chemistry (DIC, pCO2)

     Steven van Heuven(1),(2), Hans Slagter(1),(2)    (1)NIOZ
     not on board: H. Zemmelink(1),                   (2)University of Groningen
     C. Nei11(3)                                      (3)University of Bergen


Objectives

The increase in the atmospheric CO2 content is not equal to the 
cumulative emissions from human activities because about half of these 
emissions are taken up by the world's oceans. This leads to the 
increase in DIC which is the subject of the research described in the 
previous paragraph (deep-ocean carbonate chemistry). However, these 
oceanic inventory changes are not the only measure of the processes 
involved in the distribution of this anthropogenic CO2 between the 
ocean and atmosphere. Since exchange of CO2 between these two 
compartments necessarily takes place across the sea surface, global 
quantification and (temporal and spatial) integration of these fluxes 
should yield an independent measure of DIC accumulation in the world's 
oceans.

Quantification of these fluxes requires accurate knowledge of the 
partial pressure of CO2 (pCO2) of both the atmosphere and surface 
ocean. Determination of the atmospheric concentrations is now common 
practice around the world, but the determination of the highly variable 
sea surface pCO2 has historically proven to be much more complicated. 
However, several research groups around the world are involved in major 
efforts to fill in this gap, using highly specialized (though now 
standardized) equipment. Already these investigations have resulted in 
global, seasonal pCO2 maps, from which, with information of wind speed 
and atmospheric pCO2 fields, fluxes can be calculated with reasonable 
accuracy. The monitoring of the sea-surface carbonate system will 
contribute to this effort.

Work at sea

A fully autonomous, continuous surface water pCO2 system has been 
permanently installed on Polarstern since 2007. This system draws water 
from the ship's seawater supply. A steady flow of this water is led 
through a plastic 'equilibrator' vessel, filling it almost halfway 
before flowing out into the ship's drain. The air in the headspace of 
this equilibrator is circulated through a LiCor 7000 infrared gas 
analyzer. Because the air after a short while takes on the pCO2 value 
of the water, the pCO2 of the analyzed air is identical to that of the 
water. By using several sensors and methods, all measurements are 
corrected for vapour pressure and temperature effects, which may cause 
significant deviations of the equilibrated pCO2. Four calibration gases 
(0, 175, 350 and 700 patm) are available for hourly recalibration of 
the gas analyzer. Atmospheric air is measured every hour. pCO2 values 
as well as diagnostic and auxiliary data (mainly GPS and meteorological 
observations), are logged and automatically sent to the home laboratory 
through email. Operation of the pCO2 system consisted of little more 
that turning it on and keeping an eye on reference gas availability and 
the different diagnostic indicators.

In order to fully determine the state of the carbonate system in the 
surface ocean, a second of the four measurable parameters of the 
carbonate systems (DIC, TAlk, pCO2 and pH) has to be determined. From 
the work done by Craig Neill during the previous cruise leg ANT-XXIV/2, 
a continuous surface water DIC analyzer was available, which we have 
used to continue his work. This system is built up around the heart of 
the SOMMA system, but now equipped with an automatic intake and the 
capacity to measure continuously, unattended, until the coulometer 
chemicals need to be replenished. This setup allowed for the 
determination of 3 - 4 samples every hour, for a cruise-leg total of 
4500, which should allow us to determine the exact state of the 
carbonate system to an exacting degree.

The ~20 ml sampling pipette was thermostated to the temperature of the 
sample, using a second line from the sea water tap. This means that the 
pipette volume changes with the sample temperature, as does - of course 
- the sample's density. Corrections for all these effects will be 
applied after the cruise.

For the calibration of the SOMMA system (and as a means of checking the 
pCO2 system as well), the VINDTA-analyses (see 'deep-ocean carbonate 
chemistry') of the uppermost samples of the regular hydrocasts (from 
circa 10 meters depth) were used. Whenever no hydrocasts were being 
performed for a significant amount of time, samples tapped from the 
ship's seawater supply (from which the SOMMA get its water as well) 
were analyzed. The assumption that the water from 10 m depth resembles 
the water from 5 m depth (at the ships sea water supply inlet) will be 
tested for validity.



4.3  Intercomparison of carbondioxide variables with BONUS-GOODHOPE

     Steven van Heuven(1), Hans Slagter(1),     (1)NIOZ
     Hein de Baar(1)                            (2)Université de Liege
     On board Marion Dufresne:                  (3)Universidad de Las Palmas de
     Bruno Delille(2),                             Gran Canaria
     Nicolas-Xavier Geilfus(2),
     Meichior Gonzalez-Davila(3), 
     J. Magdalena Santano-Casiano(3)

For the sections from Cape Town to the Greenwich meridian, and from 
there along zero meridian to Antarctica, the CASO-GEOTRACES programme 
of Polarstern ANT-XXIV-3 was complementary to the BONUS-GOODHOPE 
programme aboard Marion Dufresne. Towards an overall integrated database 
of both expeditions, some intercomparison between both programmes had been 
envisioned.

The initial cruise tracks of Polarstern and Marione Dufresne had been 
scheduled to be overlapping, and that in principle allowed the 
positioning of stations and sampling depths at the same place. This was 
the strategy of choice for intercomparison of CO2 system measurements, 
which had already been calibrated routinely on both ships by the 
shipboard use of certified reference material (CRM, supplied by Dr. A. 
Dickson, Scripps Institute of Oceanography).

Once at sea, Polarstern, due its earlier departure, was further south 
than Marion Dufresne. On 26 February 2008 the positions and sampling 
depth horizons (pressure, salinity, temperature at 22 - 24 depths per 
station) of 21 stations with CO2 system data aboard Polarstern (then 
until 59°S, 00) which had been completed up to then were communicated to 
Marion Dufresne. These were twenty-one (21) ANT-XXIV/3 stations PS71-101 
until PS71-131 from positions 42.3379°S, 8.9946°E (101) to 59.00°S, 
0.00° (131). This allowed re-occupation of selected same stations by 
BONUS-GOODHOPE, its overall research programme, weather permitting. 
Indeed BONUS-GOODHOPE was able to occupy sixteen (16) stations BGH-44 
to BGH-78 from 46.0242 5, 5.865 E (BGH-44) to 57.5°S, 0.0365°E (BGH-78) 
with their respective CTD hydrocast numbers CTD-57 to CTD-106. Among 
these BONUS-GOODHOPE stations were ten (10) stations within 5 nautical 
miles of most nearby ANT-XXIV/3 stations of Polarstern. The listing of 
exact stations positions is available in an excel sheet.




5.  MARINE BIOLOGY

In addition to the marine biological projects 5.1. and 5.2. described 
below, one is referred to two other projects with strong biological 
focus:

3.1.7.  The effect of dynamic light conditions and iron limitation on 
        phytoplankton abundance
3.1.8.  The Southern Ocean in a high-CO2 World


5.1  The significance of viruses for polar marine ecosystem functioning
     
     Claire Evans, E. Frijling, NIOZ 
     not on board: C. Brussaard, NIOZ

Background and Objectives

Microbial communities (phytoplankton, bacteria, Achaea, heterotrophic 
protozoa and viruses) comprise the majority of the biomass in the 
oceans and drive nutrient and energy cycling, and are thereby important 
components of polar food webs. With the emergent awareness that viruses 
are major players influencing biodiversity and biogeochemical processes 
the need to elucidate their role in polar ecosystems has been 
underlined as, despite their likely importance, their quantitative 
significance has barely been studied. We aimed to complete a 
comprehensive study of the viruses and viral mediated processes of the 
Antarctic marine habitats encountered during ANT-XXIV/3. The objectives 
of this study were; 1) To examine the abundance and composition of 
viruses and their prokaryotes and eukaryotic hosts, 2) To determine 
viral induced mortality on both prokaryotic and eukaryotic microbial 
hosts alongside host growth rates and mortality due to grazing. 3) To 
gather a data set allowing comparison of the viruses and viral mediated 
processes of the Southern and Northern Polar regions. 4) To collect 
sample from which viruses might be isolated and therefore available for 
laboratory experiments.

Work at sea

Daily profiles were made of algal abundances (cyanobacteria, 
picoeukaryotes and nanoeukaryotes) by flow cytometry of fresh samples. 
Additionally samples for viral and bacterial abundance were fixed with 
glutaraldehyde, snap frozen and stored at -80°C for later analysis at 
NIOZ by flow cytomtery and SYBR Green. On experimental stations 
measurements of abundance, growth rate, diversity, grazing rate and 
viral-induced mortality were performed on the bacterial community at 
surface, chlorophyll maximum and 200 m or both the algal and bacterial 
community at the chlorophyll maximum. Details of the stations sampled 
are given in table one. At all experimental stations, samples were 
taken for viral diversity by concentrating 10 L volumes by 30 kDa 
ultrafiltration. These samples will be stored at -80°C until analysis 
by pulse field gel electrophoresis at the NIOZ. Samples for algal and
bacterial diversity were collected by filtration of approximately 1 L 
volumes of whole seawater onto 1 and 0.2 µm polycarbonate filters 
respectively which were snap frozen and stored at -80°C and will be 
analyzed at the NIOZ by denaturing gradient gel electrophoresis.

Growth rates, viral lysis and grazing of the cyanobacteria, 
picoeukaryote, and nanoeukaryote communities present were determined by 
a dilution technique whereby whole water is combined with either 30 kDa 
filtered water (virus and grazerfree) or 0.4 um filtered water (grazer-
free) in triplicate over a dilution series and incubated at in-situ 
temperature and light conditions (deck incubator). Samples for algal 
enumeration were taken from all incubations at the start of the assay 
and after 24 h, allowing the calculation of growth rate. By plotting 
observed growth rate against the level of dilution the theoretical 
growth rate in the absence of mortality was calculated along with 
coefficients of grazing and viral induced mortality.

Rates of viral induced mortality of bacteria were determined by viral 
reduction assay. Briefly, the bacterial community was concentrated by 
tangential flow filtration and resuspended in viral free water 
generated by 30 kDa ultrafiltration. The production of viruses was 
followed by sampling for bacterial and viral abundance over a 12 h 
period (subsampling every 3 h). Rates of lysogenic infection of the 
bacteria were determined in identical experiments with the addition of 
Mitomycin C, inducing lytic production of any lysogenic phage. In 
addition, rates of viral infection of bacteria will be elucidated by 
determining the frequency of infected cells which will be performed at 
the NIOZ on samples preserved with glutaradehyde. Grazing of bacteria 
was assessed by an exclusion assay whereby bacterial numbers within 
incubations filtered to remove grazers 0.8 um were compared with whole 
water incubations containing grazers. Secondary production was 
determined using the radiolabelling Leucine incorporation technique. 
Live and dead (fixed) subsamples of whole water were incubated for 4 
hours in the dark at in-situ temperature the presence of 20 pCi. After 
the incubation period the samples will be killed with the addition of 
formalin and stored until later analysis by liquid scintillation at the 
NIOZ.

Samples for virus isolation were collected from the chlorophyll maximum and will 
be screened against potential hosts at the NIOZ.


Tab. 5.1: Stations sampled

Station Type      Station       Date    Time      Lat         Long     Depth   Gear
                                                                        [m]
---------------  -----------  --------  -----  ----------  ----------  ------  -------------------------
Abundance        PS71/101-2   13.02.08  16:02  42°20.22'S   8°59.88'E  4543.0  CTD, Ultra Clean
Algal Bacterial  PS71/101-5   14.02.08  02:49  42°20.54'S   8°59.54'E  4560.0  CTD/rosette water sampler
Abundance        PS71/102-2   15.02.08  07:55  44°39.62'S   7°5.82'E   4619.0  CTD/rosette water sampler
Bacterial        PS71/102-4   15.02.08  10:33  44°39.51'S   7°5.62'E   4618.0  CTD/rosette water sampler
Abundance        PS71/104-2   16.02.08  22:44  47°39.58'S   4°16.95'E          CTD, Ultra Clean
Algal Bacterial  PS71/104-8   17.02.08  14:13  47°38.45'S   4°16.43'E  4549.2  CTD/rosette water sampler
Bacterial        P571/106-1   18.02.08  03:48  48°54.68'S   2°48.11'E  4101.4  CTD/rosette water sampler
Abundance        PS71/107-3   18.02.08  19:57  50°16.13'S   1°26.71'E  3855.0  CTD, Ultra Clean
Abundance        PS71/108-2   19.02.08  10:41  51°29.91'S   0°0.21'E   2771.7  CTD/rosette water sampler
Abundance        PS71/113-2   20.02.08  11:02  52°59.90'S   0°0.89'E   2530.3  CTD, Ultra Clean
Algal Bacterial  PS71/113-4   20.02.08  13:27  52°59.58'S   0°2.39'E   2544.2  CTD/rosette water sampler
Abundance        P571/116-1   21.02.08  06:44  54°0.07'S    0°0.01'W   2529.5  CTD, Ultra Clean
Bacterial        PS71/121-2   22.02.08  05:02  55°30.01'S   0°0.03'E   3750.3  CTD/rosette water sampler
Abundance        P571/122-1   22.02.08  14:05  56°0.03'S    0°0.23'E   3682.3  CTD, Ultra Clean
Algal Bacterial  P571/125-1   23.02.08  06:06  57°0.11 5    0°0.17'W   3837.3  CTD/rosette water sampler
Abundance        P571/127-1   23.02.08  12:05  57°30.02'S   0°0.30'E   3936.8  CTD/rosette water sampler
Abundance        PS71/131-4   24.02.08  17:49  59°0.04'S    0°0.07'W   4600.7  CTD/rosette water sampler
Algal Bacterial  PS7I/131-10  25.02.08  09:05  58°59.99'S   0°0.22'E   4608.6  CTD/rosette water sampler
Abundance        P571/137-1   26.02.08  08:06  60°30.00'S   0°0.08'W   5355.5  CTD/rosette water sampler
Abundance        PS71/141-1   27.02.08  05:34  62°0.01'S    0°0.02'W   5359.5  CTD, Ultra Clean
Bacterial        PS71/141-2   27.02.08  09:00  61°59.96'S   0°0.05'E   5359.5  CTD/rosette water sampler
Abundance        PS71/147-3   28.02.08  18:03  63°57.99'S   0°0.81'W   5193.2  CTD, Ultra Clean
Algal Bacterial  P571/150-1   29.02.08  08:11  64°59.94'S   0°0.27'E   3721.8  CTD/rosette water sampler
Abundance        PS71/150-2   29.02.08  08:34  64°59.93'S   0°0.12'E   3723.0  CTD, Ultra Clean
Abundance        P571/157-S   07.03.08  22:04  66°28.57'S   0°1.95'W   4495.0  CTD/rosette water sampler
Abundance        PS71/159-4   08.03.08  12:59  66°1.88'S    0°8.68'E   3460.5  CTD/rosette water sampler
Abundance        P571/163-1   09.03.08  14:04  66°59.94'S   0°0.18'W   4701.5  CTD, Ultra Clean
Algal Bacterial  PS71/167-2   10.03.08  07:09  68°0.04'S    0°0.00'W   4506.7  CTD/rosette water sampler
Abundance        P571/171-1   10.03.08  16:13  68°44.96'S   0°0.06'W   3629.5  CTD/rosettewater sampler
Abundance        PS71/175-3   11.03.08  08:34  68°59.77'S   0°0.23'E   3418.2  CTD, Ultra Clean
Abundance        P571/178-1   11.03.08  18:34  69°23.98'S   0°0.05'W   2011.7  CTD/rosette water sampler
Abundance        P571/184-1   13.03.08  10:54  69°0.09'S    6°59.81'W  2954.5  CTD/rosette water sampler
Abundance        P571/186-1   15.03.08  10:00  69°5.27'S   17°17.22'W  4763.5  CTD/rosette water sampler
Algal Bacterial  PS71/186-3   15.03.08  15:03  69°3.76'S   17°26.03'W  4766.2  CTD/rosette water sampler
Abundance        P571/187-1   15.03.08  20:38  68°48.20'S  17°57.61'W  4791.5  CTD, Ultra Clean
Bacterial        PS71/191-2   17.03.08  10:05  67°21.18'S  23°38.85'W  4871.2  CTD/rosette water sampler
Abundance        PS71/191-3   17.03.08  10:32  67°20.95'S  23°38.21'W  4871.7  CTD, Ultra Clean
Abundance        P571/193-6   18.03.08  20:30  66°36.44'S  27°9.39'W   4864.7  CTD, Ultra Clean
Bacterial        PS7I/193-10  19.03.08  11:44  66°35.16'S  27°20.59'W  4863.5  CTD, Ultra Clean


Preliminary results

Flow cytomtery of the algal populations revealed that with increasing 
latitude there was a change in the composition of the phytoplankton 
community shifting away from a dominance of cyanobacteria towards 
picoeukaryote cells. In addition, overall abundance of the microbial 
community was observed to decrease. Preliminary interpretation of the 
dilution experiments indicated that prior to crossing the Polar Front, 
viral lysis was a significant factor in the control of the 
picophytoplankton community (Fig. 5.1). However, viral lysis was not 
detected on any of the stations examined after this point, indicating 
that viruses play only a minor role or are not implicated in the 
control of these polar communities. Whereas, significant rates of 
grazing were routinely recorded indicating that in the Southern Ocean 
herbivory is a major process controlling primary production. Further 
work will be needed to finalize this data set and it is expected that 
this will be completed by the end of 2008.


Fig. 5.1: Growth grazing and viral lysis rate of the dominate components 
          of picophytoplankton community as determined by preliminary 
          interpretation of the dilution experiments.



5.2  Phytoplankton measurements

     Veronique Garcon, Marielle Lacombe 
     CNRS/LEGOS, Toulouse

Objectives

The ocean is getting acidified in response to atmospheric CO2 increase. 
The impact of such an acidification on primary producers is usually 
investigated through laboratory experiments or coupled 
physical/biogeochemical modeling. What is the insitu state of the ocean 
with respect to pH conditions and distribution of the various 
phytoplanktonic groups? This knowledge is a prerequisite for both 
carrying out proper models outputs validation, and establishing the 
present state.

We are interested in the Polar frontal region of Drake Passage by two 
major phytoplanktonic functional types: diatoms (siliceous 
phytoplankton) and coccolithophorids (calcareous phytoplankton). Our 
main objective is to investigate the relationship between the 
variations of acidification level (pH and alkalinity) and distribution 
of these two groups.

Work at sea

We have sampled across the Polar Front from the upper six Niskin 
bottles of all B1 CTD stations casts. Depths sampled were 10, 25, 50, 
75, 100 and 150 m. Two liters (for pigments determination) and one 
liter sample (for phytoplankton speciation) were collected and then 
filtered on board right after in the cold container. Filters for 
pigments are stored in the -80°C freezer, membrane filters for 
speciation were dried at 50°C for a couple of hours and stored in a dry 
place. Duplicates were performed all along the section. A total of 27 
CTD5 stations were sampled and 324 filters collected. All filters will 
be analyzed back in the laboratory for further determination of 
pigments composition by HPLC and for further identification and 
quantification of diatoms and coccol ithophorids biomass by microscopy.

Expected results

The distribution of the two phytoplanktonic groups will be established 
in the Polar Frontal region. By comparing with the pH and alkalinity 
conditions of the surface water masses, it will be possible to derive a 
relationship linking chemistry of seawater and the phytoplanktonic 
speciation.



6.  AUTOMATIC DETECTION OF MARINE MAMMALS

    Olaf Boebel, Carmen Böning and Olaf Klatt 
    Alfred-Wegener-Institut

Objectives

The automated detection of marine mammals has a broad range of 
applications. Population ecologists focussing on whale distributions 
and migratory patterns are interested in effective methods for 
conducting marine mammal censuses. Users of hydroacoustic instruments 
are interested in implementing reliable and effective mitigation 
methods in case adverse reactions of marine mammals are to be 
apprehended. Whales spend considerable periods of time at the surface 
as well as submerged. Diving, vocalizing mammals may be detected by 
passive sonar while surfaced whales might be recognized by means of 
their warm blow, which stands out against the cold Antarctic 
environment. The objectives of this cruises' projects were to:

a) determine the range at which the new IR lenses are capable of 
   detecting marine mammals;
b) deploy and recover acoustic recorders (PODs and Aurals) for the 
   detection of whale and seal vocalizations to be used in the context of 
   environmental suitability models;
c) test the technology and deployment procedure of a mobile, automated 
   listening station, PALAOA-S.


Work at sea

Infrared Cameras

Two infrared (IR) cameras and a visual camera, contained in protective 
housings are mounted in the crow's nest of Polarstern (Tab. 6.1). The 
cameras are oriented coaxially but view different angular segments due 
to different lenses. The IR cameras provide a resolution of 320 x 240 
pixels with 25 frames per second. The visual camera operates at 640x480 
pixels. The cameras are connected to two PCs in the scientific work 
room via an optical FireWire link. The image stream is displayed on the 
PCs and 10 second long snippets are stored every 3 minutes (typically) 
by the Matlab TM based programme WaiBlas.


Tab. 6.1: Camera system configuration

CAMERA                  label in video  lense  location
----------------------  --------------  -----  -------------------------
visual                        VIS        24°   top (+04 m)
FLIR ThermoVision A4OM        CAM1       12°   middle (28.5 above water)
FLIR ThermoVision A4OV        CAM3        7°   bottom (-04 m)


When preparing the system in Bremerhaven during Polarstern's docking 
time, a power supply cable for the A4OV camera was identified as 
broken. Temporal constraints prohibited an immediate exchange of this 
cable (which involves significant efforts to open and reseal two water 
tight feedthroughs). To solve this problem in the highly exposed area 
of the crow's nest prior to Polarstern's departure from Cape Town, two 
of us arrived early to use the time in port for an exchange of this 
cable. The work was finished successfully before Polarstern left port.

The camera system was modified with regard to its previous 
configuration as to be able to rotate it in the horizontal to be able 
to point it in the direction of whales which might eventually be 
sighted visually. Generally, however, the system was fixed, pointing in 
the direction 100 starboard from the ships heading.

Starting on 13 March 2008 the IR system was operated almost 
continuously for 360 hours, until 28 March 2008, generating some 80 
GByte of video data. Interruptions resulted mainly from hang-ups of the 
video stream, all of which could simply be solved by rebooting the 
computer or cameras. On a daily basis, both IR cameras' video data of 
the previous day were searched manually for events such as whale blows, 
seals, icebergs or birds. Interesting events were noted in event log 
files.

Data Loggers (PODs Aurals and PALAOA-S)

During a previous expedition, ANT-XXII/3, three autonomous data 
loggers, PODs (Porpoise Detectors by Chledonia Inc.) had been deployed 
as part of 3 oceanographic deep sea moorings. The instruments were to 
record click events in the frequency bands around 9, 22, 41 and 70 kHz 
which most probably constitute the centre of frequency bands of 
echolocation clicks of toothed whales. The three devices were 
successfully recovered with the moorings after an operation period of 
over 3 years (Tab. 6.2).


Tab. 6.2: Recovery of PODs

POD    Mooring   Position   Position   Deployment  Recovery    Water   POD
ID        ID       Lat         Lon        Date       Date      Depth   Depth
----  ---------  ---------  ---------  ----------  ----------  ------  ------
A401  AWI 230-5  66°00.66'  00°11.28'  08.02.2005  08.03.2008  3450 m  1557 m
                    S           E         21:00       8:25
B402  AWI 233-7  69°23.60'  00°04.29'  17.02.2005  12.03.2008  1950 m  1700 m
                    S           W         21:06      14:54
0403  AWI 207-6  63°42.20'  50°52.22'  14.03.2005   pending    2500 m  1457 m
                    S           W         02:47


While PODs are designed to record the high frequency clicks of 
odontocetes, many marine mammals vocalize in the 10 Hz to 20 kHz range. 
Detection and identification of such vocalizations requires broadband 
audio recordings. To complement such recordings from the PALAOA 
listening station north of Neumayer (Boebel et al., 2008), two 
underwater recorders (AURAL-M2 by Multi Electronique, Canada) and a 
PALAOA-S (Satellite) listening station were deployed (Tab. 6.3). The 
two Aural-M2s are incorporated in oceanographic deep sea moorings and 
are programmed to record the first 5 minutes out of sound every 4 hours 
(starting at midnight of each day).

Tests prior to deployment however showed that the system will skip 
every 48th record (i.e. the last record of every 8th day).

By contrast, PALAOA-S is designed to collect continuous sound records, 
but for a period of one day only. In a first sea-trial (that is in open 
waters), PALAOA-S was placed on an ice floe of about 2 m freeboard, 
close to the ice shelf edge in the southwestern corner of Atka Bay. The 
hydrophone was lowered over the floe's edge into the water to a depth 
of an estimated 5 m. During the course of the day, the floe drifted 
seawards with the prevailing wind driven and tidal currents away from 
the ice shelf edge. Upon recovery during the next day, PALAOA-S had 
drifted some 366 nm, to a location east of Polarstern's berthing site 
at the ice shelf (70°34.12'S, 008°08.21'W).


Tab. 6.3: Deployments of Aural-M2s and PALAOA-S. For the PALAOA-S 
          deployment, the top row indicates the deployment position, the 
          bottom row the recovery position.

ID         Mooring    Position     Position   deployment date   water   instrument
             ID         Lat          Lon                        depth     depth  
-------  ----------  ----------  -----------  ----------------  ------  ----------
                     70°37.70'S  008°08.19'W  02.03.2008 08:35
PALAOA-S      -      70°34.08'S  008°08.23'W  03.03.2008 10:20  ~200 m      5 m
  #086    AWI 230-6  66°01.13'S   00°04.77'E  08.03.2008        3450 m    189 m
  #085    AWI 232-9  68°59.74'S   00°00.17'E  11.03.2008        3370 m    206 m


Figure 6.1: Positions of AURAL deployments (yellow) and POD recoveries 
            (black). A red diamond indicates the position of the PALAOA 
            station and the two-day deployment of PALAOA-S (at a distance 
            of approximately 6 miles to PALAOA).


Preliminary and expected results

Infrared Cameras

While unobserved (i.e. not directed manually towards a sighted whale), 
the system recorded a few whale blows, seals and birds simply by 
chance, as records are taken in limited angular segments and only every 
10s out of 3 minutes. On 15 March 2008, several whales were observed 
swimming ahead of the ship while following a lead through the ice. 
Then, the camera system was pointed manually towards the lead and 
whales. In this way, 15 whale blow events were recorded. A similar 
event occurred on 24 March 2008 with Polarstern on station and whales 
present in a lead portside-astern of the ship.

Overall, the 12° camera recorded 27 snippets showing blowing whales (as 
identified by manually browsing the data), while the 7° camera recorded 
10 blows. These whales were identified as Minke whales. Earlier 
experiences had showed that Minke whales are difficult to detect with a 
24° lense due to their tendency to keep some distance from the ship and 
their relatively small and faint blow. However, the new high resolution 
(7° and 12°) lenses clearly revealed the blows, even at a distance of 
order 1 km (Fig. 6.2).

The distance d between the ship and an event (at the sea surface) was 
estimated from the number of pixels N, between the horizon and the 
event, avoiding detailed knowledge of the cameras orientation 
(including the ship's pitch, roll and heave).


                                  ⎛      ⎛r(H)⎞      ⎞
                       d = h · tan⎜arctan⎜----⎟-N · φ⎟
                                  ⎝      ⎝  h ⎠      ⎠


                            ____________
                 and  rH = √2r(E)h+h(^2)


i.e. the distance to the horizon as a function of camera height h~ 28.5 m, r(E) 
the earth radius, and φ the instant field of view (or angular segment of a 
single pixel). Errors are estimated by assuming an uncertainty in the camera 
height of ± 1 m.

Analysis of the images showed, that seals and whale blows are detectable up to 
distance of 1.5 km with both the 12° and 7° lenses.


Fig. 6.2: IR images by FL/A Thermacam A4OM with 12° lense prior (left) and 
          during peak (right) of Minke whale blow. The image to the right was 
          taken 0.24 s after image to the left. The blow was visible for the 
          duration of 8 frames, which corresponds to about 0.56 s. The distance 
          to the blow is estimated to be 1164 ±40 m. Dark areas are covered by 
          sea ice, brighter areas represent (partially) open water.
Fig. 6.3: Infrared images showing a group of seals in the far distance. Left: IR 
          CAM1 with 12° lense, the distance is estimated to 1590.4:t 53 m. 
          Right IR camera with 7°, the distance is estimated to 1588.9 ± 53 m.


Further analysis will use the collected set of IR snippets to further develop 
automatic pattern recognition algorithm while avoiding false positives.

Data Loggers (PODs, Aurals, and PALAOA-S)

The recovered three PODs appear to be in good shape and are internally dry, even 
though this was the first deployment of such instruments at depths greater than 
1500 m. The data will however only be accessible in Bremerhaven. Until then the 
instruments are stored upside down in "idle" mode.

Both pressure cases of the new Aural units have been successfully tested to a 
depth of 300 m prior to the instruments deployment at around 200 m depth. The 
deployment of PALAOA-S proceeded without complications, though it is advisable 
to mark every 1 m of the hydrophone cable to be able to estimate the deployment 
depth in the field. The collected acoustic data will be analysed in Bremerhaven 
in conjunction with recording from PALAOA.


References

Boebel, O., Kindermann, L., Klinck, H., Bornemann, H., Plötz, J., Steinhage, D., 
    Riedel, S., Burkhardt, E.(2006).Acoustic Observatory Provides Real-Time 
    Underwater Sounds from the Antarctic Ocean, EOS, 87, 361-372.




7.  WEATHER SITUATION DURING THE CRUISE LEG ANT-XXIV/3

    Wolfgang Seifert and Klaus Bult 
    Deutscher Wetterdienst

Between 5 and 9 February a strong south-easterly gale situation, well known as 
"Cape Doctor", influenced the Cape region. As a consequence the loading 
activities had to be postponed. This was one reason why Polarstern finally sat 
sail not before 10 February.

After crossing the subtropical high we reached the Subtropical Front at 40°S 
with westerly winds force 6 Bft. During the following days several secondary 
lows as part of polar frontal system crossed our course with south-westerly 
gales force 8 - 9 Bft and waves up to 7 m (Fig. 7.1a).

With the beginning of the following week the frontal zone developed in a more 
meridional shape with two dominant low pressure systems: an upper level trough 
with a surface low southwest of the Antarctic Peninsula and a steering low 
pressure system east of 30°E. Between these two systems especially close to the 
Greenwich meridian - our course track - a flat high pressure ridge developed and 
caused wind forces less than 5-6 Bft with wave heights under 2-3m (Fig. 7.1b).

During the following days a new low developed near 20°W with secondary lows 
moving from its northern flank southeast, where theses systems came in a slow 
dipolar rotation. Firstly, near the core afterwards on its southern flank 
Polarstern approached the ice shelf at Atka Bay on 2 March. During this day 
moderate winds were observed (Fig. 7.lc and Fig. 71d).

At this morning a helicopter accident happened in good flight conditions as 
described in a special report(1).
---------------------------------
(1) Report about weather conditions on the occasion of a flight accident for LBA




On 5 March Polarstern left the Atka region in fair weather conditions. During 
the following days two polar lows influenced our course with stormy weather of 
wind force 8 - 9 Bft and increasing waves of about 4 m. This was observed 
several times during the expedition when a cold upper low produced some 
vorticity centres with sheering wind systems at the surface (Fig. 7.2a).

Operating along the Greenwich meridian again Polarstern sailed at the western 
flank of a dominant low east of 15°E with mostly south-eastern winds forces 6 - 
7 Bft (Fig. 72b). By 13 March, we headed west through the Weddell Sea.

New low pressure systems north and northeast of our track showed that we were on 
the cold side of the frontal zone with mostly southerly or south-easterly winds 
force 6 - 7 Bft (Fig. 72c). Sailing along the northern ice edge weather improved 
temporarily. After 18 March a new low pressure system moved from northwest in 
south-eastern direction and caused winds from northeast to east up to force 7 
Bft. Without the shelter of the ice the ship would have experienced the effect 
of higher waves (Fig. 7.2d).

The circulation changed during the following days because of a more unstable 
frontal zone with an increasing wave number from 4 to 5. That's why a new 
cyclone could establish close to 65°N and 30°W with a secondary low moving on 
its eastern flank southwards. Polarstern was affected by several trough centres 
which caused surface lows with wind forces 7 - 9 Bft. However waves only 
increased up to 3 m because of the short fetch. At the western side of this 
system mainly southerly to southeasterly winds with force 5 - 7 Bft prevailed 
but the pacific system developed secondary lows near the northern part of the 
Antarctic Peninsula so that Polarstern was influenced some days by easterly to 
north-easterly winds which affected a compression of the northern ice edge (Fig. 
7.3a). On 30 March Polarstern approached Jubany Station as scheduled. By then 
moderate winds were observed.

Because of strong windward-effects at the South-Shetlands the cloud base lowered 
to 300 ft and fog prevailed at times with strong variations of visibility and 
cloud base. Nevertheless most of the planned flight operations could be done. 
However, the flight to Artigas Station (Uruguay) had to be cancelled dew to 
impossible flight conditions with a cloud base of 100 ft and visibility under 
300 m. Polarstern left King George Island in the afternoon of 31 March heading 
northeast.

During the following days we reached the frontal zone between two dominant long 
wave systems in an area between 100°W und east of 45°W (Fig. 73b). The wind 
situation then was relatively moderate with an average wind force of about Bft 6 
- 7. Only occasionally westerly storms with force 8 - 9 Bft were observed. 
Because of the relatively long fetch the sea state was more influenced by swell 
than by wind sea with significant heights up to 4 m.

In the beginning of the two last weeks at sea Polarstern sailed at the southern 
flank of a low pressure zone reaching from the Bellingshausen Sea to the 
Malvinas and South Georgia (Fig. 73c).

Therefore the predominant wind direction was northeast with wind speed about 20 
kn. This situation remained until 13 April while the ship was heading towards 
Cabo San Diego. At the end of the research operations on 14 April the frontal 
zone established and intensified from the eastern Pacific to southern Patagonia 
(Fig. 7.3d). On board Polarstern a strong wind field from southwest with force 
up to 8 - 9 Bft and waves up to 5 m were observed. The last two days in lee of 
the continent were not influenced by any meteorological event so that Polarstern 
arrived at Punta Arenas on 16 April as scheduled.


Fig. 7.1: Sea surface and air pressure distribution for the periods
          a: 10 - 17 Feb 2008
          b: 18 - 22 Feb 2008
          c: 23 - 27 Feb 2008
          d: 28 - 03 Mar 2008
Fig. 7.2: Sea surface and air pressure distribution for the periods
          a: 04 - 08 Mar 2008
          b: 09 - 12 Feb 2008
          c: 13 - 17 Feb 2008
          d: 18 - 23 Mar 2008
Fig. 7.3: Sea surface and air pressure distribution for the periods
          a: 24 - 28 Mar 2008
          b: 29 - 04 Apr 2008
          c: 05 - 09 Apr 2008
          d: 10 - 14 Apr 2008




8.  ACKNOWLEDGEMENT

ANT-XXVII/3 was the most difficult cruise for all of us. In the course of the 
helicopter accident on 2 March 2008 two cruise participants lost their lives and 
three were injured so that they had to be evacuated. Although overshadowed by 
that dramatic event, we were able to collect extensive data sets and outstanding 
samples during that cruise and we achieved our logistic tasks. This was a 
further proof of the exceptional professionalism and the never ending commitment 
of the Polarstern crew. For that we would like to express our heartfelt and 
sincere thanks to Master Schwarze and his entire crew. We want to thank as well 
all those, even if we are not able to state them all by name, who contributed to 
the success of the cruise by their support on shore during planning, preparation 
and while we had been at sea.



APPENDIX

A.1 PARTICIPATING INSTITUTIONS

A.2 CRUISE PARTICIPANTS

A.3 SHIP'S CREW

A.4 STATION LIST PS71



A.1  BETEILIGTE INSTITUTE/
     PARTICIPATING INSTITUTES ANT-XXIV/3

                            Adresse
                            Address
------------------------------------------------------------------------------
AWI                         Alfred-Wegener-Institut
                            für Polar- und Meeresforschung
                            in der Helmholtz-Gemeinschaft
                            Am Handelshafen 12
                            27570 Bremerhaven / Germany

CNRS LEGOS                  LEGOS Laboratoire d'Etudes en Geophysique et
                            Oceanographie Spatiales
                            Unite Mixte de Recherche CNRS, UPS, CNES, IRD
                            18 avenue Edouard Behn
                            31055 Toulouse / France

DESE                        Dept. of Earth Science & Engineering
                            Imperial College
                            London SW7 2AZ / UK (participating, but not on
                            cruise)

DWD                         Deutscher Wetterdienst
                            Geschäftsbereich Wettervorhersage
                            Seeschifffahrtsberatung
                            Bernhard Nocht Str. 76
                            20359 Hamburg /Germany

Heli Service                Heli Service International GmbH
                            Im Geisbaum 2
                            63329 Egelsbach / Germany

IFM-GEOMAR                  Leibniz-Institut für Meereswissenschaften IFM-
                            GEOMAR
                            Düsternbrooker Weg 20
                            24105 Kiel / Germany

IGM                         Institut für Geologie und Mineralogie
                            Universität zu Köln
                            Zülpicher Strasse 49 a/b
                            50674 Köln / Germany

IUP                         Institut für Umweltphysik (IUP) Ozeanographie
                            Institute of Environmental Physics Oceanography
                            Otto-Hahn-Allee 1
                            D-28359 Bremen I Germany

KORDI                       Korean Ocean Research and Development Institute
                            1270 Sa-dong
                            Sangrok-gu, Asan
                            Kyunggi-do P0 Box 29
                            425-600 Korea

Laeisz                      Reederei F. Laeisz (Bremerhaven) GmbH
                            Brückenstrasse 25
                            27568 Bremerhaven I Germany

LEMAR                       Laboratoire des Sciences de lEnvironnement
                            Mann (LEMAR),
                            CNRS-UMR 6539
                            Institut Universitaire Européen de la Mer (IUEM)
                            Technopole Brest-Iroise
                            Place Nicolas Copernic 29280
                            Plouzané I France

LOCEAN                      LOCEAN (Laboratoire d'Oceanographie et du
                            Cl imat: Experimentation et Analyses N umeriques)
                            Unite Mixte de Recherche CNRS, UPMC, MNHN,
                            IRD
                            Université Pierre et Marie Curie
                            Tour 45-55 5E 4 place Jussieu
                            75252 Paris cedex 05 I France

LSCE                        Laboratoire des Sciences du Climat et de
                            lEnvironnement / Institut Pierre Simon Laplace
                            Domaine du CNRS
                            Bat 12 - avenue de la Terrasse
                            F - 91198 Gif-sur-Yvette Cedex I France

MPI Chemie                  Max- Planck- lnstitut für Chemie
                            Abteilung Geochemie
                            Postfach 3060
                            55020 Mainz / Germany

NIOZ                        Koninklijk Nederlands lnstituut vor Onderzoek der
                            Zee
                            Department for Marine Chemistry and Geology
                            P.O. Box 59
                            1790 AB Den Burg I The Netherlands

OPTIMARE                    OPTIMARE
                            Am Luneort 15a
                            27572 Bremerhaven I Germany

RMfCA                       Section of Mineralogy and Geochemistry
                            Department of Geology
                            Royal Museum for Central Africa
                            Leuvensesteenweg, 13
                            B-3080 Tervuren I Belgium

University Brussels         Vrije Universiteit Brussel
                            Analytical and Environmental Chemistry
                            Pleinlaan 2
                            B-1050 Brussels I Belgium

University Las Palmas       Departamento de QuImica
                            Universidad de Las Palmas de Gran Canaria
                            Campus de Tafira
                            35017 Las Palmas /Spain

University Liege            Chemical Oceanography Unit
                            Astrophysics, Geophysics and Oceanography
                            Department
                            Université de Liege, Belgium
                            Allee du 6 Aoüt, 17
                            4000 Liege I Belgium

University of Groningen     Faculteit Wiskunde en Natuurwetenschappen
                            University of Groningen
                            Nijenborgh 4
                            9747 AG Groningen I The Netherlands

XU                          XU Research Center for Environmental Science
                            Xiamen University
                            Xiamen 361005 I China




A.2  FAHRTTEILNEHMER/
     PARTICIPANTS

Name/         Vorname/       Institut/     Beruf/
Last name     First name     Institute     Profession
------------  -------------  ------------  ---------------------------  -----------
Alderkamp     An ne-Carlijn  University    Biologist
                             of Groningen   
Baars         Oliver         IFM-GEOMAR    PhD student, geochemistry
Beauverger    Mickael        LOCEAN        Engineer, oceanography       From K.G.I.
Bluhm         Katrin         IFM-GEOMAR    PhD student, biology
Boebel        Olaf           AWI           Physicist
Boening       Carmen         AWI           PhD student, oceanography
Bontes        Babette        NIOZ          PhD student, biology
Bult          Klaus          DWD           Technician, weather station  
Cai           Pinghe         XU            Geochemist
Cristini      Luisa          AWI           Physicist
Croot         Peter          IFM-GEOMAR    Marine chemist
de Baar       Hein           NIOZ          Geochemist
Evans         Claire         NIOZ          Biologist
Fahrbach      Eberhard       AWI           Oceanographer
Frijling      Erwin          NIOZ          Chemist
Garcon        Veronique      CNRS LEGOS    Oceanographer                From K.G.I.
Gebler        Madlen         IUP           Student, physics
Gerringa      Loes           NIOZ          Chemist
Gremlowski    Lars           AWI           Student, chemistry
Gronholz      Alexandra      IUP           Student, physics
Heckmann      Hans-Hilmar    HeliService   Pilot
Heller        Maija          IFM-GEOMAR    PhD student, chemistry
Huhn          Oliver         IUP           Physicist
Hwang         San Chui       KORDI         Oceanographer                From K.G.I.
Kartavsteff   Annie          LOCEAN        Engineer, oceanography       From K.G.I.
Klatt         Olaf           AWI           Physicist
Laan          Patrick        NIOZ          Engineer, chemistry
Lacombe       Marielle       CNRS LEGOS    PhD student, oceanography
Lee           Jae-Hak        KORDI         Oceanographer                From K.G.I.
Legoff        Hervé          LOCEAN        Engineer, oceanography       From K.G.I.
Lohse         Charlotte      IPY teacher   Teacher
                             programme
Middag        Rob            NIOZ          PhD student,
                                           biology/geochemistry
Monglon       Thierry        LOCEAN        Technician, oceanography     From K.G.I.
Monsees       Matthias       OPTIMARE      Technician, oceanography
Neven         Ika            University    PhD student, geochemistry
                             Groningen
Nunez-Ribuni  Ismael         AWI           Physicist
Ober          Sven           NIOZ          Engineer, chemistry
Paz Martinez  Andrea                       Observer                     From K.G.I.
Provost       Christine      LOCEAN        Oceanographer                From K.G.I.
Robert        Maya           AWI           PhD student, biology
Rohardt       Gerd           AWI           Oceanographer
Sander        Hendrik        OPTIMARE      Physicist
Seifert       Wolfgang       DWD           Meteorologist
Sennechael    Nathalie       LOCEAN        Oceanographer                From K.G.I.
Slagter       Hans           NIOZ          MSc student, chemistry
Spadone       Aurelie        LOCEAN        PhD student, oceanography
Stichel       Torben         IFM-GEOMAR    PhD student, geochemistry
Stimac        Mihael         HeliService   Helicopter mechanic
Strothmann    Olaf           AWI           Technician, oceanography
Sudre         Joel           LEGOS         Engineer, oceanography
Sweet         Elisabeth      AWI           PhD student, geochemistry
Theisen       Stefan         IPY teacher   Teacher
                             programme
Thuroczy      Charles-       NIOZ          PhD student, geochemistry
              Edouard
Van Heuven    Steven         NIOZ          PhD student, biology
Van Ooijen    Jan            NIOZ          Engineer, chemistry
Van Slooten   Cornelis       NIOZ          PhD student, biology
Venchiarutti  Celia          AWI           Chemist
Stimac        Ingrid         AWI           Technician, chemistry

Two cruise participants lost their lives during the helicopter accident on 
2 March 2008:
    Willem Polman, NIOZ, Technician, geochemistry
    Stefan Winter, HeliService, Pilot

Three cruise participants had to return home from Neumayer station after being 
injured during the helicopter accident on 2 March 2008: 
    Martin Klunder, NIOZ, PhD student, geochemistry 
    Carsten Möllendorf, HeliService, Helicopter mechanic 
    Alice Renault, LOCEAN, PhD student, oceanography




A.3  SCHIFFSBESATZUNG / SHIP'S CREW

     No.  Name                         Rank
     ---  ---------------------------  ---------------------
      1.  Schwarze, Stefan             Master
      2.  Spielke, Steffen             1.Offc. from Neumayer
      3.  Fallei, Holger               1.Offc to Neumayer
      4.  Farysch, Bernd               Ch.Eng.
      5.  Becker, lilo                 2.Offc.
      6.  Peine Lutz                   2.Offc.
      7.  Dugge, Heike                 3.Offc.
      8.  Sokoll, Herbert              Doctor
      9.  Hecht, Andreas               R.Offc
     10.  Minzlaff, Hans-Ulrich        2.Eng.
     11.  Sümnicht, Stefan             2.Eng.
     12.  Schäfer, Marc                3.Eng.
     13.  Scholz, Manfred              Elec.Tech.
     14.  Fröb Martin                  Electron.
     15.  Himmel, Frank                Electron.
     16.  Muhle, Helmut                Electron.
     17.  Nasis, Ilias                 Electron.
     18.  Loidl, Reiner                Boatsw.
     19.  Reise, Lutz                  Carpenter
     20.  Bäcker, Andreas              A. B.
     21.  Guse, Hartmut                A. B.
     22.  Hagemann, Manfred            A. B.
     23.  Schmidt, Uwe                 A. B.
     24.  Stutz, Hein-Werner           A. B.
     25.  Vehlow, Ringo                A. B.
     26.  Wende, Uwe                   A. B.
     27.  Winkler, Michael             A. B.
     28.  Preußner, Uwe                Storekeep.
     29.  EIsner, Klaus                Mot-man
     30.  Hartmann, Ernst-Uwe          Mot-man
     31.  Ipsen, Michael               Mot-man
     32.  Pinske, Lutz                 Mot-man
     33.  Voy, Bernd                   Mot-man
     34.  Müller-Homburg, Ralf-Dieter  Cook
     35.  Martens, Michael             Cooksmate
     36.  Silinski, Frank              Cooksmate
     37.  Jürgens, Monika              1.Stwdess
     38.  Holger, Irene                Stwdss/KS
     39.  Czyborra, Bärbel             2.Stwdess
     40.  Gaude, Hans-Jürgen           2.Steward
     41.  Huang, Wu-Mei                2.Steward
     42.  Möller, Wolfgang             2.Steward
     43.  Silinski, Carmen             2.Stwdess
     44.  Wu, Chi Lung                 Laundryman





REFERENCES

Amachi, S., Kamagata, Y., Kanagawa, T. and Muramatsu, Y., 2001.  Bacteria 
    Mediate Methylation of Iodine in Marine and Terrestrial  Environments. 
    AppI. Environ. Microbiol., 67(6): 2718-2722.

Anschutz, P., Sundby, B., Lefrancois, L., Luther III, G.W. and Mucci, A., 
    2000. Interactions between metal oxides and species of nitrogen and  
    iodine in bioturbated marine sediments. Geochimica et Cosmochimica  Acta, 
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CCHDO DATA PROCESSING NOTES

Date        Person       Data Type   Action          Summary
----------  -----------  ----------  --------------  ---------------------------
2012-07-26  Bob Key      CTD/CrsRpt  Submitted       to go online 
            CTD data file for ANT XXIV/3. This is another of the PANGAEA format 
            files.

            I'm working with German partners on the bottle file. Have requested 
            final version of the cruise report

2012-09-07  CCHDO Staff  CTD         Website Update  Available under 'Files as received' 
            The following files are now available online under 'Files as 
            received', unprocessed by the CCHDO.
               ANT-24-3-cruise-report_PRELIM.pdf
               ANT-XXIV_3_phys_oce.tab.tsv 

2012-09-25  J Kappa      CrsRpt      Submitted       pdf and text versions 
            I've placed 2 new versions of the cruise report:

            a12_06AQ20080210do.pdf
            a12_06AQ20080210do.txt

            into the co2clivar/atlantic/a12/a12_06AQ20080210/directory.

            Both docs include summary pages and CCHDO data processing notes.

            The pdf version also includes a linked Table of Contents and links 
            to figures, tables and appendices.

            Both will be available on the cchdo website following the next 
            update script run.

2013-03-15  Bob Key      CrsRpt      Submitted       to go online 
            Detailed Notes
            Today I'm uploading the final cruise report. Previous version of 
            report was Prelim. Filename is Fah2010a.pdf
            Steven van Heuven has provided me with a final (but incomplete) 
            version of the bottle data. In the next few days I'll translate 
            flags (from ODV) and reformat. 

            If you could reformat the CTD data we can finish this one up in 
            short time. As a separate chore I'll try to obtain the missing 
            isotope data, but we shouldn't wait for that.

2013-03-19  CCHDO Staff  CrsRpt      Website Update  Available under 'Files as received' 
            Detailed Notes
            The following files are now available online under 'Files as 
            received', unprocessed by the CCHDO.
              Fah2010a.pdf

2013-03-19  Bob Key      BTL         Submitted       to go online 
            Detailed Notes
            This is an updated version of the file I previously uploaded for 
            this cruise. There are numerous minor error fixes and all of the 
            included parameters are "final". Still expected are CFC and H3/He 
            data from Bremen. I sent a request for these data earlier today, but 
            expect they will be proprietary for awhile yet. This file completes 
            my work on this cruise until those data are received.

            This file should simply replace (rather than parameter update) 
            previous submission. The full parameter set will be available at 
            BODC as a GEOTRACES file. Given this the previous e-mail regarding 
            BCO=DMO submission an U/Th isotopes is now moot. 

2013-03-19  CCHDO Staff  BTL         Website Update  Available under 'Files as received' 
            Detailed Notes
            The following files are now available online under 'Files as 
            received', unprocessed by the CCHDO.
              06AQ20080210.exc.csv 

2013-03-28  Bob Key      CFCs        Submitted       to go online 
            Detailed Notes
            This file is the same as the other recently submitted version except 
            that this contains the CFC data and the header has been modified 
            accordingly. Oliver Huhn and Monika also supplied an addition for 
            the cruise report (also attached). 

2013-03-29  CCHDO Staff  CFCs        Website Update  Available under 'Files as received' 
            Detailed Notes
            The following files are now available online under 'Files as 
            received', unprocessed by the CCHDO.
              06AQ20080210.exc.csv
            readme_ant24_3_tracer_ohuhn_IUP_bremen_germany.pdf 

2013-04-05  Bob Key      BTL         Submitted       edited header, includes He data 
            Detailed Notes
            This is the same file I uploaded on 3/28/13 except that the header 
            has been edited and the He data from Huhn & Rhein have been added. 

            BCO-DMO will (does?) have a different version of this file that will 
            include trace metals, biologicals, partical isotopes, etc. 

2013-04-05  Bob Key      CrsRpt      Submitted       CFC report to be added to CrsRpt 

2013-04-08  CCHDO Staff  BTL         Website Update  Available under 'Files as received' 
            Detailed Notes
            The following files are now available online under 'Files as 
            received', unprocessed by the CCHDO.
              06AQ20080210.exc.csv 

2013-04-08  CCHDO Staff  CrsRpt      Website Update  Available under 'Files as received' 
            Detailed Notes
            The following files are now available online under 'Files as 
            received', unprocessed by the CCHDO.
              readme_ant24_3_tracer_ohuhn_IUP_bremen_germany.pdf 

2013-04-17  Jerry Kappa  CrsRpt      Website Update  Final pdf version online
            Detailed Notes
            The final pdf version of the cruise report is now online.  Updates include:
            • Final cruise report
            • Final CFC report
            • Updated/expanded data processing notes
            • CCHDO-generated station track figure

            Corrections:
            • Table 3.2, p146 truncated (right hand column missing). 
              Replaced with same table from preliminary report.
            • Step 2, p. 80 formula missing.  Copied formula from preliminary report
            • Step 2, p. 81 formula missing.  Copied formula from preliminary report
            • Step 1, p. 82 formula missing.  Copied formula from preliminary report

2013-04-17  Jerry Kappa  CrsRpt      Website Update  Final text version online
            Detailed Notes
            The final text version of the cruise report is now online.  Updates include:
            • Final cruise report
            • Final CFC report
            • Updated/expanded data processing notes

