If symbols do not display correctly change your browser character encoding to unicode CRUISE REPORT: A12 (Updated JAN 2012) 1. HIGHLIGHTS CRUISE SUMMARY INFORMATION WOCE Section Designation A12 Expedition designation (ExpoCodes) 06AQ200211_2 Chief Scientists Eberhard Fahrbach/AWI Dates 2002 NOV 24 - 2003 JAN 23 Ship R/V Polarstern Ports of call Cape Town, South Africa 39°3.35'S Geographic Boundaries 0°6.74'W 25°14.03'E 69°53.08'S Stations 100 Floats and drifters deployed 9 RAFOS floats deployed Moorings deployed or recovered 9 moorings recovered & re-deployed Recent Contact Information: Eberhard Fahrbach Alfred Wegener Institute für Polar- und Meeresforschung Bussestrasse 24 • D-27570 Bremerhaven (Building F-214) • GERMANY Phone: +49(471)4831-1820 • Fax: +49(471)4831-1797 Email: Eberhard.Fahrbach@awi.de 2. THE EXPEDITION ANTARKTIS-XX/2 Cape Town - Cape Town November 24, 2002 to January 23, 2003 2.1 SUMMARY AND ITINERARY Dieter K. Fütterer The second leg of RV POLARSTERN expedition ANT-XX was devoted to a multidisciplinary research programme in the eastern Weddell Sea and Riiser Larsen Sea. It focused on oceanographical, geochemical and sedimentological projects carried out along two transects, from north to south along the Prime Meridian and from south to north along 23° longitude east (Figure 2.1-1). Apart from the scientific programme, the - as early as possible in the season - supply of Neumayer and Kohnen stations and the logistic support of AWI polar aircrafts as well as research projects at Neumayer played an important role on this leg. Its scheduling was done on site absolutely depending on sea-ice conditions. A major goal of the hydrographic investigations was the recovery (after two years of deployment) and redeployment of nine mooring systems along the Prime Meridian in the framework of the WECCON project (Weddell Sea convection control) which was started already in 1996. This project was complemented by a complete CTD (conductivity, temperature, depth) and water sampling programme along the Prime Meridian and along 23° longitude east for Carbon dioxide investigations, CFC tracers, naturally radionuclide tracers and chlorophyll and particle flux investigations as well as for a small biological project dealing with virioplankton and oligotrophic bacteria. The marine geological investigations concentrated mainly to sediment coring and sampling of a channel-levee system on the continental slope of the southern Riiser Larsen Sea (see GeoBox in Figure 2.1-1). Swath sonar bathymetric measurements with the Hydrosweep system planned to contribute to the AWI Bathymetric Chart of the Weddell Sea (BCWS) and subbottom echosounding profiling with the Parasound system in support of the sedimentological project were only partially successful due to very specific obligations by the German Federal Office for the Environment (UBA) for operating all hydro acoustic devices, e.g. echosounding systems. However, extensive experience was gathered on the efforts and needs to run a permanent passive acoustic and visual monitoring of marine mammals while doing acoustic profiling (see Chapter 2.4). RV POLARSTERN set sail in the evening of November 24, 2002 with an international team of 51 scientists and technicians from seven countries, PR China, Germany, Greece, Mexico, The Netherlands, South Africa, United Kingdom, and 43 crew and left the harbour of Cape Town (South Africa) on a south westerly course heading for the Prime Meridian at 51 degree latitude south (Figure 2.1-1). Fine weather and calm sea conditions during the first days of the cruise enabled POLARSTERN to make good progress. After leaving the South African EEZ, a continuous en-route bathymetric and acoustic sediment profiling survey was started using the ship's swath sounding Hydrosweep system and the Parasound system, respectively. On November 26, a test station for the CTD/rosette system at 39°33'S, 11°05'E and a towing test at different speed of the hydrophone streamer system for acoustic mammals monitoring were carried out successfully. Figure 2.1-1: Cruise track of RV POLARSTERN during ANT-XX/2 Regular hydrographic station work started on November 27, along the TOPEX / POSEIDON ground track #133 along which two pressure inverted echosounders (PIES) were deployed. At regular distance of about 70 nautical miles a CTD (Conductivity, Temperature, Depth) sonde and attached rosette water sampler were used to provide the various projects with hydrographic data and water samples. Strong gale during these days, lasting until December 04, caused difficult working conditions. Two CTD stations had to be cancelled because of heavy sea state. The Prime Meridian was reached on November 30, to continue CTD and rosette sampling at regular distances of half degree latitude or 30 nautical miles from 50°S to 69°S as part of the WECCON (Weddell Sea Convection Control) project. As a major component of WECCON, nine mooring systems deployed two years ago along the Prime Meridian were to be recovered and redeployed. The first mooring system was recovered under extremely difficult sea state conditions on December 01. The first attempt to deploy the new system had to be stopped. It was successfully deployed only later the next day when sea state conditions had improved slightly. First icebergs were sighted in the morning of December 04, and the ice edge consisting of dense but loosely packed drift-ice was met unexpectedly far north, at about 56°30'S during the afternoon of the same day. Ice coverage intensified and increased from 5-7 tenths to 8-9 tenths while CTD station work progressively moved south. Wind force decreased, and together with moderately strong coverage of relatively soft and thin one-year ice, working conditions changed considerably to the better. On December 07, crossing 60° south latitude, POLARSTERN entered the area under the Antarctic Treaty legislation. To perform the special requirements laid down by the German Federal Office of the Environment (UBA) for operating the swath sonar Hydrosweep and sediment echosounder Parasound systems and all other hydroacoustic devices scientists set up a passive acoustic as well as a visual monitoring of marine mammals. Once marine mammals, seals or whales, were sighted or recorded, the ship's sonar systems (Hydrosweep swath sounder and Parasound subbottom echosounder) had to be shut down for a certain period and reactivated only if no other mammal had been sighted meanwhile. Especially the visual monitoring increased the general watch keeping duties for all scientists tremendously. CTD station work was continued until December 10, at 64°S, west of Maud Rise where a mooring system was recovered and deployed before POLARSTERN at almost midnight shaped course for Atka Bay and Neumayer Station. Very convenient ice conditions, 4/10 of ice coverage and wide open water made good headway. Ice conditions changed to the worse during December 11, when thick flows of strongly ridged multi-year ice with a thick snow cover became more and more predominant. Tough ice conditions prevailed until the next morning when the dense pack ice opened slowly and POLARSTERN reached the wide open coastal polynya stretching from 5°W to 15°W (see Figure 2.3-la). Late in the evening of December 12. POLARSTERN arrived at Atka Iceport which - according with the early season - was completely covered by a complete and intact ice cover. By midnight the ship came alongside the exposed "Nordanleger" in the lee of a huge grounded iceberg where the ice-edge reaches a height of approximately 12 m. Cargo operations started early in the morning of December 13, and - meeting fine weather conditions - were finished in the late afternoon of December 14. While the vessel stayed at the "Nordanleger" satellite transmitters were mounted during helicopter flights on three suitable icebergs for tracking them during melting Supported by helicopter, two hydroacoustic experiments to record seal songs from open leads in the sea ice cover of Atka Bay were carried out as well. Other scientists and crew that had riot visited Neumayer Station before took the chance of a helicopter shuttle to the station. Late in the evening of December 14, POLARSTERN left Atka Bay and steamed through the widely open waters of the polynya on northeasterly course along the ice edge for the Prime Meridian at about 69°S, slightly north of Trolltunga. Shortly before midnight POLARSTERN met with the Russian research vessel ACADEMIC FEDOROV which passed nearby on her way for Neumayer Station. Between December 15 and 20 intensive CTD station work and sediment sampling along the Prime Meridian from 69°20'S to 64°S in the western Lazarev Sea was carried out. Additionally, four mooring systems were recovered and deployed and a 19 m long piston core was recovered at 61°S. Improving ice conditions changed from heavy pack and 8-10 tenths coverage in the south to almost open water in the north, and made station work increasingly easier. By means of a number of helicopter flights four icebergs between 69°S and 64°S were marked by satellite transmitters. From December 21 through December 26 a transect of hydrographic CTD stations and geological multi-corer stations was sampled at regular distances of 38 nautical miles each, from the Prime Meridian at 61°S, north of Maud Rise, to 66°26'S, 15°55'E east of the Astrid Ridge in the western Riiser Larsen Sea. A sound-source mooring was deployed at 64°31'S, 09°50'E and at 64°53'S, 10°57'E use of the in-situ pump system was made for sampling large volume samples for natural radionuclide tracers. Regular sampling was interrupted from December 24 to 25 to celebrate the Christmas Eve. From December 26 to January 06 Hydrosweep bathymetric swath sonar profiling for areal mapping of erosional channels and Parasound sediment profiling for mapping the thickness of the sedimentary cover and identifying suitable sediment coring sites were carried out in parallel with sediment sampling by gravity corer and multi-corer (MUC) in the so called GeoBox in the southern Riiser Larsen Sea. Regular CTD station work was continued to extend the hydrographic transect started at the Prime Meridian to the southeast as far as to 69°55'S, 25°30'E near the ice shelf edge of the Prinsesse Ragnhild Kyst. There, ice surveys by helicopter along the shelf ice edge revealed 8-9 tenths coverage of thick multi-year ice extending far to the west in the direction for the Astrid Ridge. Therefore, it was decided on December 30, not to take direct course to Erskinebukta in the west but to choose a more northerly course where thinner one-year ice eased the ice conditions, as experienced the days before. The New Year's Eve was celebrated while transiting from the eastern to the western part of Riiser Larsen Sea. On January 02, 2003 an acoustic experiment to record and distinguish sounds of marine mammals, e.g. seals, without the strong background noise of RV POLARSTERN was carried out using one of POLARSTERN's life boats in the drift-ice zone of the northern Riiser Larsen Sea. Sediment profiling in the GeoBox in general but specifically in the densely ice covered area of the southern Riiser Larsen Sea near the shelf ice edge was severely hampered by complying with the specific environmental restrictions of the German Federal Environmental Office (UBA) for the use of active acoustical devices. From January 07 through the afternoon of January 15 intensive hydrographic as well geoscientific sampling was carried out along 23° east longitude. CTD/rosette and fluorometer casts were taken regularly each half degree latitude or 30 nm in distance, Long piston cores and surface samples by multi-corer were taken on selected sites at 60 to 90 nm distance, precise locations identified from existing Hydrosweep and Parasound records or from online surveys where available according to environmental injunctions. Station work was generally favoured by calm weather conditions. However, piston coring in greater water depths, deeper than 5000 m, was substantially hampered by high swell during January 10 to 12. Hydrosweep swath sounding and Parasound sediment profiling was carried out continuously north of 60°S. An exceptional event occurred on January 15 when during station work for several hours altogether more than 20 Humpback whales played around the vessel showing not dread of the vessel itself and of ongoing sampling activities or of active sonar systems. During the night from January 15 to January 16 the hydrographic transect along 23°E was finished at 53°S In the same night a large low pressure system caused fresh gale and heavy sea preventing POLARSTERN from further piston coring. A fundamental decision was required how to spend the remaining station time of the cruise, to wait on site for increasing weather conditions to proceed with piston coring along 23°E or to escape as fast as possible to the north to sample the Agulhas system around 40°S with CTD and in-situ pumps for a hydrographical-geochemical project and to sample additional piston cores en route where feasible. POLARSTERN left the area around 52°S and sailed north assisted by strong southerly winds and swell astern. During daytime of January l8 to January 2l the waters of the Agulhas Retroflection and associated gyre system of the Agulhas Rings at 40 to 36°S and 20 to 14°E were sampled on four long-lasting stations by in-situ pumps and CTD while night-time was used for transit between stations. Refreshing winds and swell and strong currents during January 19 caused difficult working conditions on station, cancellation of CTD casts and delayed beginning of station work on January 20. Bright sunshine and calm sea saw the final station work of this cruise when the last CTD came on board in the late afternoon of January 21, After 60 days at sea and a distance of about 8100 nautical miles, RV POLARSTERN arrived on schedule in Cape Town in the early morning of January 23, 2003. 2.2 WEATHER CONDITIONS DURING ANT-XX/2 Hans-Arnold Pols Shortly after leaving Cape Town RV POLARSTERN encountered a narrow line of strong winds reaching gale force; caused by a pressure gradient between the South Atlantic subtropical high and a small low off the coast of Namibia. During the first night at sea. wind increased up to force 9 Bft. On November 26, following a calm passage of the subtropical high, the ship entered the zone of westerly winds between 40 and 60°S. From that time on it was affected on several occasions by intense depressions, rapidly moving eastward in the zonal flow. On November 30 POLARSTERN reached the Greenwich Meridian. On that day a cyclone, with a pressure of 960 hPa at its centre, crossed the vessel's course. At the back of this low the wind increased up to force 10 to 11 Bft, with gusts of force 12 Bft. The wind remained at force 8 for several days after the passage of this storm, with continued westerly cyclonic flow. On December 03 another intense low pressure system passed the ship. Near the centre of that low a measurement of 945 hPa was recorded. This proved to be the lowest pressure reading of the cruise. However, the wind at force 9 Bft did not reach the same intensity as before. When this depression moved eastward, a region with weak pressure gradients was entered. In this region the ship was affected by winds with mean values of force 5 Bft, and the swell reduced proportionally. On December 04 POLARSTERN reached the sea-ice edge off the Antarctic coast. The sea ice considerably damped the swell. In the following weeks the ship faced continuous pack-ice conditions. These were coped with successfully. Intensive depressions, moving on a Northerly path, were met but these did not affect the work on POLARSTERN. Wind speed reached force 6 to 7 Bft for some periods. In mid December, the Neumayer-Station was supplied under a weak high pressure influence and nearly moderate winds. The following week POLARSTERN headed back northwards following the Prime Meridian. Between a ridge of high pressure, reaching from the South Atlantic to the Weddell Sea, and a westward moving depression at the Riiser Larsen Sea, wind increased up to force 8 Bft. on December 21. The ship then found open water in a polynya close to 62°S. Altering course to south east for the Riiser Larsen Sea, and making for the GeoBox working area, a ridge of high pressure crossed the route. Weak pressure differences then prevailed until the beginning of January. In the first week of the New Year, air pressure varied only 8 hPa between low and high. During that time wind only rarely reached force 6 Bft. The easterly flow prevailed with force 4 to 5 Bft. during Christmas and from January 4 to 6 calm conditions was observed with the sea as smooth as a mirror. This coincided with periods of low ceiling and poor visibility, occasionally accompanied by fog and snowfall. Dense multi-year sea-ice made work more difficult on reaching Prinsesse Ragnhild Kyst. By January 10, 2003 RV POLARSTERN had reached 63.5°S, 23.5°E. Now in open water and heading northwards again, the course was affected by a low which then developed into a dominating feature. About evening the wind had increased up to force 8 to 9 Bft. with associated wave-heights of 4-5 m. For the next few days, and into the third week of January, the ship stayed near to the centre of that low. Although wind strengths decreased, wave heights of 4 m were still prevalent. On January 15 an intense low developed from a wave disturbance and passed to the north of the ships cruise. Wind increased from force 2 Bft, at noon to force 9 to 10 Bft, by midnight. The south-westerly storm lasted until the evening of the following day. Later, the wind decreased a little, due to a weak ridge of high pressure, but another intense depression then approached from the west. For the rest of its continuing cruise to the north RV POLARSTERN met stormy northerly winds. The cold-front of a low was trailing in the north and several wave disturbances developed. The low's influence extended up to the latitude of 35°S. Ahead of the front, on January 18 north-westerly winds of force 8 Bft., with gusts reaching gale force, were observed. After the passage of the front, RV POLARSTERN entered the trough of the same intense low. Here the ship was affected by wind speeds of force 9 to 10 Bft., and with gusts up to force 12. Wave heights of 8 m and more were encountered, with very short wave-periods. During January 20 these conditions improved only slowly. However, bright sunshine and calm sea prevailed during station work the following days and on arrival in Cape Town in the morning of January 23, 2003. Figure 2.2-1: Time series of wind speed and directions during RV POLARSTERN cruise ANT-XX/2. 2.3 SHIP-BASED OBSERVATION OF SEA ICE THICKNESS AND CHARACTERISTICS Olaf Klatt, lsmael Nunes, Sandy J. Thomalla and Sebastian Wahl The sea-ice thickness distribution is a fundamental parameter for defining the extent of ocean-atmosphere interaction within the sea ice zone. It cannot be measured remotely; hence the need for in situ measurements to determine the distribution and thickness of different ice types within the pack ice zone. As a contribution to the to the multidisciplinary Antarctic sea ice zone research project ASPeCt (Antarctic Sea ice Processes and Climate) a standard set of observations were made almost hourly from the bridge of RV POLARSTERN. These include the ship's position and an estimate of the aerial ice coverage, thickness, floe size, topography and snow cover of the three dominant ice thickness categories within a radius of approximately 0.5 nautical miles of the ship. The ice thickness classification is shown in Table 2.3-1. Furthermore, the meteorological conditions such as air and water temperature, wind speed and direction, cloud cover and visibility were recorded at every observation. The entire data set, which consists of about 300 single observations, is submitted to ASPeCt. Table 2.3-1: Ice thickness classifications used for the ship-based observations Ice Type Ice Thickness (m) -------------------- ----------------- Classification ⎛ Frazil new | Shuga <0.1 ice | Grease ⎝ Nilas pancakes no defined range young grey ice 0.10-0.15 young grey-white ice 0.15-0.3 first year ice 0.3-0.7 first year ice 0.7-1.2 first year ice >1.2 multi-year ice <10 brash no defined range fast ice <2 At noon on December 4, 2002 RV POLARSTERN reached the ice edge at 56.5°S and 0.0°E. Satellite images showed, at this time almost the whole Weddell Sea was covered with ice (Figure 2.3-la), but two areas of low ice concentrations (polynyas) can be identified at the cruise track. The first is located at the Prime Meridian (64°S), the second at about 10°W 70°S close to the shelf ice off Ekström Ice Shelf. During December the ice has vanished over almost the entire area of investigation and only an ice field at about 10°E in front of the Riiser Larsen Ice Shelf is visible (Figure 2.3-1b). As an example of ship-based observations, the aerial ice coverage and thickness for the Prime Meridian is shown in Figure 2.3-2. At the northern end of the Prime Meridian (56- to 62°S) the mean total ice coverage was roughly 60%. The dominant ice type was first year ice with a thickness of around 50 cm. Both the ice coverage and thickness between 62-64°S were very low and the polynya could be identified (Figure 2.3-1). South of 67°S the first year ice became denser with up to 90% aerial coverage and increased in thickness to 150 cm. RV POLARSTERN left the ice on the afternoon of the January 3, 2003. Figure 2.3-1: Total ice concentration of the Weddell Sea at (a) December 11, 2002 and (b) January 6, 2003 Figure 2.3-2: Ice cover (a) and thickness of ship-based observations at the Prime Meridian 2.4 OBSERVATION AND IDENTIFICATION OF MARINE MAMMALS Wolfgang Dinter and Gerd Kuhn The obligations for marine mammal monitoring and observation as a mitigation measure related to the permissions for high powered acoustic devices as Hydrosweep and Parasound during POLARSTERN research cruise ANT-XX/2 provided the rare possibility to get a widely full-time survey of marine mammals along the ship's track as a byproduct. The spotting rate is believed to be quite high due to the high deployment of manpower even though most observers were initially not experienced in this task. This resulted in a relatively high number of spottings where species initially were not identified but it gave an overlook about abundance and distribution patterns. The visual survey width depended strongly on visibility/visible range (sea state, weather conditions, ice-cover, ridges on ice-floes) and heights of platform but was generally good for identification up to a radius of 500 m around the ship and decreased with distance due to the factors mentioned. Observations began already on November 27, 2002 at 43°37'S 7°60'E for training purposes while steaming SW towards the Prime Meridian transect, although it was obligatory only for the Antarctic Treaty Area south of 60°S which was reached on late December 7. After leaving the Antarctic Treaty Area on January 11, 2003 observations were made only occasionally until reaching Cape Town on January 23, 2003. Additional marine mammal records could be made from >600 nm surveys on six helicopter flights in the region between 67-70°13'S and 14°56'-25°14'E. METHODS Observation was done by scientists and technicians (mainly oceanographers, geologists, and geochemists) besides their other regular duties and work programmes. Each observation turn lasted in general no longer than two hours, to avoid fatigue of observers. Position of the observers was generally on the bridge, ~19 m plus eye's heights above water level, and voluntarily in some cases for one observer on the crows nest, ~28 m plus eye's heights above water level. Numerous binoculars (Steiner 7 x 50) for distant observation were available throughout the bridge area. Initially, marine mammal watch-keeping was conducted with three observers, but according to a change in the observing obligations, after December 21, 14:00 UTC, general observation was made by two observers during transit and by one observer while on station. Observation was cancelled during hours of darkness in more northerly latitudes and on very long stations, where the acoustic devices were shut down. Observation was also cancelled or took place only with a reduced personnel of one observer during times when the acoustic device were shut down on some transit transects due to too many mammals and/or already known sea bottom structure and at times where it was intended to avoid the streamer to be damaged in too heavy ice. ASSESSMENT OF THE OBSERVATION EFFORT Generally it was obvious that the detection rate and observation quality is depending on: A) physical optic: • visibility or visible range (sea state, weather conditions, ice-cover, ridges on ice-floes), • height of platform (seals rested frequently behind ridges on ice floes / whales in wavy seas → detectable from the crows nest but sometimes not from the bridge; • state of windows of bridge and crows nest: in open water frequently covered by spray and salt, B) observers: • motivation (such as personal interest or conflict of interests), • experience, → detection rate, → behavioural documentation, → behavioural assessment, → contrary interpretations; • individual visual ability (e.g. short-sighted vision), • number of observers. EVALUATION OF THE SIGHTINGS IN RELATION TO DISTRIBUTION AND BEHAVIOUR Although there were regions without any marine mammal sightings along the ship's track it was obviously, that there are patterns of abundance and distribution clearly correlated with patterns of ice-cover and therefore with the seasonal variation. General Antarctic marine mammal abundance and distribution patterns could be confirmed for the surveyed area through this intense observation. Most whales enter Antarctic waters with the seasonal breaking up of the pack-ice and further melting of the drift-ice and thus are found in higher numbers at ice-edges and along fringes of open water areas even though some whales are reported to over-winter at polynyas and leads. There are only few records of young or juvenile whales in Antarctica. Therefore, it was surprising to spot one juvenile humpback whale (Megaptera novaeangliae) together with two adults already on December 3 at 54°01.5'S, 0°06.7'W relatively close to the northern ice-edge. Whales (Minke, Humpback) approached R/V POLARSTERN exclusively only on station but all sighted species showed a behaviour range from being unaffected over avoidance to flight responses during transit cruise of the ship. This corresponds well with the general behaviour of Minke whales described at Richardson et al. (1995, p: 272 and references therein). Flight responses could not be related to the use of the different hydroacoustic systems because these were immediately shut down with any spotting. Those Minke whales that approached the ship could clearly be identified as belonging to the southern species Antarctic minke whale (Balaenoptera bonaerensis). Even though there were spotted many Minke whales or like Minke whales" alone (Table 2.4-1), the mean sighting number was 2.44 whales per sighting Weddell seals (Leptonychotes woddellii) were most numerous in colony-like assemblages on fast ice and pack-ice along coastal polynyas. Leopard seals (Hydrurga leptonyx) appeared to be mostly at the outer ice-edge or at the fringe of coastal polynyas and larger open water patches while Ross seals (Ommatophoca rossii) were seen in areas of denser ice-cover. Crabeater seals (Lobodon carcinophagus) were spread throughout the entire ice-belt and were as well as the two species mentioned last mostly encountered alone (mean sighting rate of all seal species 1.36) and resting/sleeping behind ice-ridges. All seals of all species resting on ice reacted to the ship passing by either by no reactions at all or by waking up and sometimes associated with a threatening gesture (raising head and open mouth) or by a short flight response on the ice. Short range (2-7 m) flight response was nearly exclusively on ice and from 358 shipboard sightings only three times into the water. On the other hand a few (three) seals fled out of the water onto ice-floes in the immediate vicinity of the ship when it approached. The assumption related to this behaviour is that Antarctic seals during evolution never had terrestrial (on ice) predators but in the water in contrast to all northerly seals that typically flee into the water due to their main enemies (humans, polar bears) on land (on ice). REFERENCE Richardson, W.J., Greene, C.R., Malme, C.J. & Thomson, D.H. (1995): Marine Mammals and Noise.- Academic Press, San Diego. Table 2.4-1: Summary of marine mammals observations. Shipboard sightings Watchkeeping. 27.11.02 10:00 - 10.01.03. 15:40; 333 sightings from shipboard, it was always counted the higher number when not indicated exactly; (d = definitely, pr = probably, po = possibly | | | | t | | | | | | | | | | | S l | A | | | | | | | U | | M | o e | m | | U | | | | | n | L | i | u n | o | | n | C | | | | i | i | n | t o | u | H | i | r | W | | L | d w | k w | k | h s | x' w | u w | d s | a s | e s | R s | e s | e h | e h | e | e e | s h | m h | e e | b e | d e | o e | o e | n a | a | | r | a | p a | n a | e a | d a | s a | p a | t l | M l | w | n w | B l | b l | t l | a l | e l | s l | a l | i e | i e | h | h | e e | a e | i s | t s | l s | s | r s | f s | n s | a | B a | a s | c s | f | e | l | | d | i | k | l | o l | k | k | i | r | | | | e | e | e | t- e | e | | e | | | | | d | | s | s | d | | d | | | | | | | | | | | | | | | | |(pr, | |(d,pr,|(d,pr,|(d,pr,| |(d,pr,|(d,pr,|(d,pr,|(d,pr | | po) |(d)| po)| po)| po)| | po)| po)| po)| po) -----------|------|------|---|------|------|------|------|------|------|------|------ on ice | | | | | | | 124 | 194 | 23 | 7 | 3 in water | 25 | 59 | 56| 13 | 7 | 9 | 2 | 2 | 1 | | | | | | | | | 128 | 196 | 24 | | | 171 | | | | | | 358 | | | | | 529 | | | | | | | | | | 171 Whales in 70 sightings (171/70, average 2.44); 358 Seals in 263 sightings (358/263, average 136); 529 Marine Mammals sighted from shipboard (529/333, average 159) Sightings on 6 helicopter transectflights/triangular courses Minke uniden- Crabeater Weddell Ross Leopard lengths whales tified seals seals seals seals of survey Flight (d) seals (d,pr,po) (d,pr,po) (d,pr,po) (d,pr,po) flight waypoints ---------- ------ ------- --------- --------- --------- --------- --------- ---------------------- 27.12.02 13 1 1 1 134,04 nm 67°18'S 14°59'E ice-survey 68°18,84'S 14°56,6'E 67°18,73'S 14°52,03'E 67°19,96'S 15°25,75'E 28.12.02 6 3 1 109,01 nm 68°01,79'S 20°34,53'E snow samples 68°61,56'S 20°56,44'E 68°35,61'S 21°28,32'E 68°54,47'S 21°54,68'E 68°11,31'S 21°18,17'E 29.12.02 43 7 1 2 117,24 nm 68°50,75'S 22°26,8'E snow samples 69°10,38'S 22°27,43'E 69°30,85'S 22°26,5'E 69°50,72'S 22°29,45'E 68°53,58'S 22°39,17'E 30.12.02 22 63 29 1 1 ~120 nm 69°53,19'S 25°13,62'E acoustic 70°00,91'S 25°01,20'E sample at 70°12,15'S 24°03,87'E coastal 69°53,2'S 25°13,62'E polynya 31.12.02 32 26 1 68,12 nm 68°53,9'S 21°30,74'E snow samples 68°44,09'S 20°42,9'E 68°33,43'S 21°33,68'E 68°15,19'S 21°34,99'E 68°50,75'S 21°9,72'E 02.01.03 1 2 6 1 53,21 nm 68°34,1'S 17°12,88'E snow samples 68°35,22'S 17°10,98'E 68°35,53'S 16°17,8'E 68°11,84'S 16°42,75'E 68°18,18'S 16°44,27'E 7 115 103 30 6 3 7 257 264 Overall helicopter survey length: ~602 nm = 1115 km; Effective flight survey width = ± survey width from shipboard due to flight velocity CONCLUSIONS The high number of recorded seals from helicopter is related to the area but even more to the heights of the platform, where many seals behind ice-ridges might not be detectable from shipboard. The habitat relevance for Weddell seals and the general biological importance of the coastal polynya was evident. The low number of whales was most probably due to the early season and to the related dense ice-cover at this region. Overall marine mammal sightings during ANT XX-2 | | | | t | | | | | | | | | | | S l | A | | | | | | | U | | M | o e | m | | U | | | | | n | L | i | u n | o | | n | C | | | | i | i | n | t o | u | H | i | r | W | | L | d w | k w | k | h s | x' w | u w | d s | a s | e s | R s | e s | e h | e h | e | e e | s h | m h | e e | b e | d e | o e | o e | n a | a | | r | a | p a | n a | e a | d a | s a | p a | t l | M l | w | n w | B l | b l | t l | a l | e l | s l | a l | i e | i e | h | h | e e | a e | i s | t s | l s | s | r s | f s | n s | a | B a | a s | c s | f | e | l | | d | i | k | l | o l | k | k | i | r | | | | e | e | e | t- e | e | | e | | | | | d | | s | s | d | | d | | | | | | | | | | | | | | | | |(pr, | |(d,pr,|(d,pr,|(d,pr,| |(d,pr,|(d,pr,|(d,pr,|(d,pr | | po) |(d)| po)| po)| po)| | po)| po)| po)| po) ---------------------|------|------|---|------|------|------|------|------|------|------|------ sightings from | | | | | | | 124 | 194 | 23 | 7 | 3 shipboard on ice | | | | | | | | | | | | | | | | | | | | | | sightings from | 25 | 59 |56 | 13 | 7 | 9 | 2 | 2 | 1 | | shipboard in water | | | | | | | | | | | | | | | | | | 128 | 196 | 24 | | | 171 | | | | | | 358 | | | | | | | | | | | | | | | 6 sighting events | | | | | | ~42 | | | | | from shipboard | | | | | | | | | | | after 10.01.03 | | | | | | | | | | | | 213 | | | | | | 358 | | | | | | | | | | | | | | | 6 helicopter | | 7 | | | | | 115 | 103 | 30 | 6 | 3 surveys | | | | | | | | | | | | | 220 | | | | | 615 | | | | | | | | | | | | | | | overall sighted | | 835 | | | | | | | | | marine mammals | | | | | | | | | | | | | | | | | | | | | | animals approaching | | 11/7 | | | | 3/1 | 1/1 | 2/2 | 1/1 | | the ship on station | | | | | | | | | | | 27.11.02-10.01.03 | | | | | | | | | | | | | | | | | | | | | | animals approaching | | | | | | 34/3 | | | | | the ship on station | | | | | | | | | | | after 10.01.03 | | | | | | | | | | | 2.5 MAX-DOAS MEASUREMENTS OF ATMOSPHERIC TRACE GASES FOR SCIAMACHY GROUND TRUTH Magdalirii Halasi On RV POLARSTERN cruise ANT-XX/2, as also on the cruises Ant-XX/1 and /3, Heidelberg University runs a MAX-DOAS measurement programme. The main objective of these measurements is the identification and concentration of minor gases such as BrO, SO2, HCHO, H2O, JO, O3, NO2, OClO, O4 and others. The South Polar Region and the Atlantic are areas of rare atmospheric measurements. That is why the measurements take place in the whole cruise of RV POLARSTERN. A very important fact of the measurement is the validation of the SCIAMACHY-instrument on the European ENVESAT satellite which started during March 2002. One can use the satellite's information only by comparing with real measured values. During 1990, 1993 and 2001/2 similar measurements were done with great success The method used for the detection of the different gases is the DOAS (differential optical absorption spectroscopy). This method makes it possible to measure different tropospheric gases in the different heights. On this cruise, due to the fact that there was a big oceanographic activity, the measurements were concentrated to a relatively small region. For this experiment this fact is a pity but due to the fact that this area is of so rare atmospheric observation, the data are of great worth. 2.6 MARINE SOURCES OF REACTIVE ORGANO-IODINES AND BROMINES David Wevill The aim of this project was to investigate the sources of reactive halogen radicals such as 0 and BrO. Air monitoring was carried out using an automated Perkin Elmer Turbomass GC-MS, The sampling interval was -70 mins and the instrument was running 24 h a day excluding blanks and calibrations. Of the thirteen species monitored (species include CH3l, CHBr3, CH2Cll and CH212) only nine were detected so far and will be measuring for the next leg of the cruise. The species not detected were the very short-lived compounds which last only 5-20 mins at noon. A few water samples were also taken from 50, 20 and 11 m (the former pair from CTD and the latter from the seawater pump on board). The results obtained need further scrutiny due the possible presence of algae in the Millipure water used for blanks. Later it is hoped that a combination of our data with ocean colour information from the SeaWIFFs satellite as well as sea / air temperature can help to determine the role of the open ocean as a source or sink for the compounds of interest. Continuous CO measurements were also taken during the cruise with an Aerolaser instrument and showed the expected drop in concentration once we had moved below the polar circle. Bottle samples were also taken each day around noon UTC on the transit to Neumayer for post analysis of non-methane hydrocarbons. 2.7 CARBON DIOXIDE INVESTIGATIONS IN THE ANTARCTIC CIRCUMPOLAR CURRENT AND EASTERN WEDDELL GYRE Mario Hoppema and Dorothee C.E. Bakker Modifications of the global carbon cycle, by the burning of fossil fuel and changes in land use, have led to an increase in atmospheric carbon dioxide (CO2) which has the potential to increase the greenhouse effect of the atmosphere, in turn leading to increased global temperature. The deep oceans are, in principle, able to take up almost all of this excess CO2, but only on a time scale which is much longer than the one associated with the anthropogenic perturbations. This is related to the typical mixing and residence times of the deep and bottom waters of the oceans, which are of the order of 1000 years. Thus studies in areas where interactions between the deep and the surface ocean occur, such as the Southern Ocean with the Weddell Sea, are extremely useful for the study of CO2 uptake and its distribution. While the atmospheric CO2 increase is well documented, the oceanic increase is hard to monitor due to the high natural variations and the large amount of CO2 present in the oceans. Our overall objective is to trace the anthropogenic CO2 in the deep and surface waters of the Antarctic Ocean and to investigate what factors exert influence on the CO2 distribution. Substantial progress in these issues can only be made when data series become available. Data from this cruise will extend the longest combined oceanic time series (since 1984) of CO2 and transient tracers, hydrography, nutrients and oxygen at the prime meridian. WORK AT SEA CO2 parameters have been investigated along a latitudinal section at the Prime Meridian, one section northeast to southwest across the Weddell Sea from the Prime Meridian to about 23°E, and one quasi-latitudinal section along 23°E crossing the entire Weddell Gyre at that location (see Figure 2.1-1). Parameters that were measured include the total inorganic carbon content (TCO2) and the partial pressure of CO2 (pCO2 ). Vertical TCO2 profiles of the entire water column were determined from discrete water samples taken from the rosette sampler. About 2000 water samples were analyzed, i.e. at almost all hydrographic stations, where generally a triplicate analysis was made for each sample. The pCO2 was determined in the surface water quasi-continuously from the sailing ship. TCO2 was determined by a high-precision coulometric method using an automated sample stripping system. Briefly, the method is as follows. A sample of seawater is acidified with phosphoric acid and stripped with high-purity N2 gas. The extracted CO2 is, with the N2 carrier gas, passed through a solution containing ethanolamine and an indicator. This solution is electrochemically back-titrated to its original colour and the amount of coulombs generated is equivalent to the amount of CO2 in the sample. The measurements are calibrated and corrected against an internationally recognized TCO2 standard (obtained from Prof. Dickson of Scripps, U.S.A.). Continuous measurements of the pCO2 in water and marine air were done using an infra-red analyzer (Li-Cor). A continuous water supply is passed through an equilibrator, where every minute the headspace gas is analyzed for its CO2 content, thus giving pCO2 in the surface water. Marine air was pumped continuously from the crow's nest into the laboratory and sub-sampled every three hours. The measurements are calibrated with standard NOAA gases. As the pCO2 is strongly dependent on temperature changes, final data will only be available pending corrections for the temperature increase of the water while flowing from the ship's keel into the laboratory. Analyses of TCO2 and online pCO2 were performed using equipment put at our disposal by the Royal Netherlands Institute for Sea Research (NIOZ, Texel). At a few stations pCO2was measured at samples throughout the water column as drawn from the rosette. This was done using a discrete pCO2 analysis system of the University of East Anglia. PRELIMINARY RESULTS Total carbon dioxide Unfortunately, we cannot as yet present final results for TCO2 and PCO2. Some general patterns can be discerned, though. A general feature of the TCO2 distribution is that, although the TCO2 values in the Southern Ocean surface water are high compared to other surface ocean regions, they are low in comparison with the deep and bottom water. The TCO2 minimum in the surface water is due to phytoplankton which utilises CO2. Below the thermocline, a TCO2 maximum is found associated with the temperature maximum of the Warm Deep Water (WDW). Near the bottom relatively low TCO2 values were measured in Weddell Sea Bottom Water (WSBW). This water mass originates partly from the shelf waters of the Weddell Sea, which are low in TCO2. Partial pressure of CO2 The measurement of pCO2 during the entire cruise period resulted in a large, high spatial resolution data set. Mostly modest under- and over-saturation were observed in the area of investigation. However, two regions fall outside this trend. At the Prime Meridian the region contiguous to the Antarctic continent showed dramatic undersaturation. This includes not only the coastal area, but also the region further offshore. The other large region with large under-saturation is the northeastern Weddell Gyre along 23°E. Such strong under-saturation can only be caused by intense phytoplankton primary production in these regions. 2.8 INVESTIGATIONS ON PHYSICAL HYDROGRAPHY: WEDDELL SEA CONVECTION CONTROL - WECCON Since 1996 moorings were deployed along the Prime Meridian (Figure 2.8-1) and redeployed every two years, as was done during this cruise. The two southernmost moorings covered the area of the coastal current. Westward of Maud Rise there are three moorings equipped with temperature-conductivity recorders from approximately 250-750 m depth to monitor the change in the stratification. This data are imported to study the possible pre-conditioning for the occurrence of a polynya. The four northern moorings are at the westward flowing branch of the Weddell Gyre and the transition into the Antarctic Circumpolar Current (ACC). This region is characterized by fronts, which also effect the elevation of the sea surface. Thus bottom pressure recorders in the three northernmost moorings are used to record the change of the sea surface elevation and from these records the shift of the ACC can be determined. The sea surface elevation was compared with the satellite sea surface height measurements from TOPEX/Poseidon. The ACC was also described with the full coverage of temperature conductivity recorders in this region. Inverted echo sounders are placed on top of the six southern moorings to measure the sea-ice draft and the variability of the yearly sea ice coverage. The instrumentation of the deployed moorings (Table 2.8-2) has not changed compared to the instrumentation of the recovered moorings (Table 2.8-1) but in addition two sound sources have been attached in mooring 229 and 231 at 850 m depth each. A third sound source was deployed as a single sound source mooring near 10°E Figure 2.8-1: Vertical section along the Prime Meridian with the moored instruments. Mooring AWI227 to AWI239 are the moorings which have been replaced. In addition sound sources were attached in moorings AWI229, AWI231, and in AWI240 which is a newly deployed one at 10 °E. The mooring work started with mooring AWI239 and the first part ends with mooring AWI229 before steaming on direct course to Neumayer Station. After the supply activities the mooring work was continued from the south, starting with mooring AWI233 towards mooring AWI230. The sound source mooring AWI240 was deployed on the south-east transect to the GeoBox (see Figure 2.1-1). The two northern moorings were replaced in open water. Due to rough weather conditions the deployment of AWI239 was stopped. The next day conditions became slightly better and the deployment could be finished. The sea ice edge was found north of AWI227 and at the mooring position the ice coverage ranged from 8/10 to 9/10. All further moorings were recovered under extremely closed ice cover with only a few small leads. Because the prototype of an acoustic unit (TT801) failed, the Posidonia positioning system was used. The successful recovery of all moorings during this cruise suggests that Posidonia may warrant a complete recovery even under difficult ice conditions. It was the first successful use of Posidonia for mooring recovery, therefore the following section exemplifies the recovery routine of one of our moorings. 2.8.1 MOORING RECOVERY WITH POSIDONIA Posidonia is an acoustic ultra short baseline positioning system of the IXSEA OCEANO company (France). The transducer array is fixed on a platform to be installed in the ships moon pool. The moon pool is locked when breaking through the ice. Thus the transducer array can only be installed on station and further ice breaking is not possible. Only cautious maneuvering of the ship within leads is possible once the transducer array is installed. The installation of the transducer array occupies approximately 45 minutes. The Posidonia processing unit is connected to the ships navigation system as well to the pitch and roll sensors. The system was operated from a PC with special positioning software. The system is able to track acoustic transponders which can be placed on underwater vehicles or in moorings. These transponders must be Posidonia compatible transmitting multi frequency shifted key (MFSK). One of the moorings double releases can transmit MFSK and also one transponder at the moorings top. Thus it was possible to position and track at least one unit. The release command can be generated for Posidonia compatible releases. The PC was placed on the bridge and therefore one can directly communicate with the navigation officer during the mooring positioning and release. The transducer array was installed when RV POLARSTERN had reached a lead close to the mooring location. Afterwards the positioning software was started and the transponder/releaser set-ups were loaded into the program from the configuration file, which is needed for Posidonia compatible transponders. Before the transponders can reply on their specific interrogate frequency for positioning, an enable command has to be transmitted. When this command is confirmed, the main positioning routine starts. It shows two graphs for plotting the horizontal and vertical distances between the ship and the transponder. Another window displays the calculated transponder position in latitude, longitude and depth in meters. There is also a status window, showing which of the four receivers detected a signal from the transponder. An interrogate signal was transmitted every five seconds. As soon as all four receivers have detected a reply from the transponder, its position is displayed. For moorings that have been deployed with the anchor first, the position measured with Posidonia was the same as being noticed after the deployment. For moorings that have been deployed in open water with anchor last, it was found that the position was not very far off the calculated position. Once Posidonia has found the position of the mooring the navigation officer sets a marker from this position or the radar screen, which shows the surrounding sea ice field. If the mooring was in a region of heavy sea-ice coverage the mooring was not released. Instead the ice drift was observed to find a lead passing the mooring. As soon as a lead has reached the mooring position a release command was send. This can be done directly from the Posidonia software. After the release positioning was continued and the Posidonia PC-display shows decreasing transponder depth. It occurred that the moorings top-floats appeared directly in the assumed 50 m wide lead. Because the mooring will drift with the current, which may set differently than the drifting sea ice, the mooring can miss the lead. In this case the positions from the Posidonia system help to fix the region to search for float packages, which may appear between the ice flows. Even in open water Posidonia helps to improve the mooring recovery. It was found that release commands being transmitted with the standard deck units (TT301 and TT801) and the 30 m cable hand-held-transducer failed if the release is placed in very deep water (greater 4000 m). During this cruise it could be verified that the release did not fail if the ship's noise was reduced disconnecting the propellers. But Posidonia transmitted release codes are able to release deep moorings even with running propellers or thrusters. 2.8.2 ICEBERG TRACKING To estimate the fresh water transport by icebergs, 10 satellite tracked transmitters were deployed there upon. These iceberg markers were manufactured by the "Denk Manufaktur" company, Gr. Kneten, Germany. The markers determine their 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 six hours once a week only, 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. Three markers are equipped additionally with an air pressure sensor. The ARGOS transmitters of these markers are operating in a 90 seconds continuous mode, providing three hourly air pressure data to the GTS. 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 without using additional floats. 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 is excessive. A helicopter was used to deploy markers on icebergs. Figure 2.8-2 shows the locations of the marked icebergs. The icebergs were chosen along the cruise track with a maximum flight distance of 20 nautical miles. Three markers were deployed during the supply activities at Neumayer Station. 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. Table 2.8-3 gives a summary of all icebergs marked. Snow was sampled for the tracer group from IUPB. Figure 2.8-2: Map of the ice bergs with deployed ARGOS transmitters. Numbers are the ARGOS Ids. Underlined Ids indicate the transmitters that are additionally equipped with air pressure sensor. The drift is shown for the period given in Table 2.8-3. Data collection from CLS via direct computer link and to do the data processing and validation is assigned to Optimare company, Bremerhaven, Germany. Daily updated iceberg tracks are available from Gerd Rohardt (grohardt©awi-bremerhaven.de). 2.8.3 DEPLOYMENT OF PRESSURE INVERTED ECHO SOUNDERS - PIES To monitor the Antarctic Circumpolar Current (ACC) transport, two Pressure Inverted Echo Sounders (PIES) were purchased from the University of Rhode Island and deployed across the ACCs. The instruments are located on the TOPEX/Poseidon ground track number 133 (Figure 2.8-3), complementing a PIES array between the South African coast and about 40°S, which is currently being deployed by Deidre Byrne, University of Maine along the same satellite ground track. PIES deliver bottom pressure and travel times of sound signals from the bottom to the sea-surface, effectively providing a measure of average temperatures, bottom pressure variations and sea surface height. After the planned recovery of the instruments in austral summer 2004/2005, the data shall be used to extract baroclinic and possibly barotropic transport variations within the gap spanned by the PIES. A high resolution bathymetric profile between Cape Town and the two PIES was recorded with the Hydrosweep System (Figure 2.8-4 and Figure 2.8-5). Figure 2.8-3: Map of Pressure Inverted Echo Sounders (PIES) deployment positions (square boxes near 45° and 50°S at the crossover points of TOPEX/Poseidon tracks 133, 98 and 48) together with selling positions often freely drifting ARGO/APEX floats. Bottom topography from Smith & Sandwell. Figure 2.8-4: Bathymetry around deployment position of PIES-1 at 44°39.75'S, 7°05.03'E. The bathymetry was recorded by Hydrosweep during cruise ANT-XX/2. Isobaths are spaced by 50 m. Figure 2.8-5: Bathymetry around deployment position of PIES-I at 50°15.O1'S, 1°25.00'E. The bathymetry was recorded by Hydrosweep during cruise ANT-XX/2. Isobaths are spaced by 50 m. 2.8.4 DEPLOYMENT OF ARGO/APEX FLOATS The international ARGO (Array of Real Time Global Oceanography) project aims to set on the order of 3000 profiling floats into the world ocean to establish a real-time operational data stream of upper (<200D rn) ocean temperature and salinity profiles. Since 2001 the AWI contributes to this program with nine APEX floats, roving primarily between 50-60°S, which cycle every seven days between the sea surface and their drift depth near 800 m. This year the fleet that was augmented by another ten floats, set south of 60°S and cycling at ten days intervals (Figure 2.8-3). 2.8.5 DEPLOYMENT OF RAFOS FLOATS AND SOUND SOURCE MOORINGS AT MAUD RISE The Ranging and Fixing of Sound (RAFOS) technology has been used widely in moderate latitudes to provide high-resolution trajectories of neutrally buoyant floats by means of underwater acoustics. It is based on travel time measurements of a coded sound signal between a moored sound source and the moving float. However, at high latitudes, this technique is expected to work at considerable shorter ranges only, and the Maud Rise RAFOS Experiment (MARE) is designed as a first test to explore the ranges to be expected, while simultaneously trying to unveil the mesoscale circulation patterns around Maud Rise. To this end, three sound sources were moored and nine floats were launched in the vicinity of Maud Rise (Figure 2.8-6, Table 2.8-6 and Table 2.8-7). Figure 2.8-6: Map of Sound Source moorings and RAFOS float deployment sites around Maud Rise. Asterisks mark the sound source mooring positions, with circles indicating 100 and 200 km ranges. Dots mark the setting positions of nine RAFOS (Ranging and Fixing of Sound) floats. Bathymetry according to Smith & Sandwell. The sources are refurbished sources, with some major problems that could only provisionally be fixed in Bremerhaven before shipment. Sound source 21 showed signs of previous leakage at the high voltage feed-through, which was provisionally fixed with Scotch Fill. Sound source 19 and 21 could only be addressed through the internal interface and hence could not be vacuum checked before deployment. Sound source 49/14 had the high voltage feed-through replaced and spliced to the external cable leading to the transducer. 2.8.6 MEASUREMENTS WITH THE VESSEL MOUNTED ACOUSTIC DOPPLER CURRENT PROFILER VM -ADCP AWI, OPTIMARE A 150 kHz ADCP is mounted in the ship's hull and monitors continuously the velocity profile in the upper water column. Navigation is provided by the Marine Inertial Navigation System (MINS). Due to problems with one of the four transducers the ADCP was run in the 3-beamsolution mode for the whole cruise up to January 3, 2003, when it was switched off for repair. The decision to switch the VM-ADCP off that early, was made to take the opportunity to demount the instrument in calm weather conditions near the ice edge. The instrument will be sent to the manufacturer RD Instruments for repair after the cruise. A preliminary scan through the data indicates no problems. The final processing will be done with the CODAS software at home. Table 2.8-1: Moorings recovered at the Prime Meridian. ADCP = RDI Inc. self contained acoustic doppler current profiler. ACM-CTD = Falmouth Scientific Inc. three-dimensional acoustic current meter with CTD head (CTD = Conductivity, Temperature, Depth). 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 SBE16 recording temperature, conductivity, and pressure, ULS = Christian Michelsen Research Inc. upward looking sonar to measure the sea ice draft. SBE26 = Seabird Electronics SBE26 bottom pressure recorder. CT = Seabird Electronics SBE37 recording temperature and conductivity. CT-P = Seabird Electronics SBE37 recording temperature, conductivity, and pressure. Date Water time Record Latitude depth of 1st Instrument Serial Instrument length Mooring Longitude (m) record type number depth (m) (days) -------- ---------- ----- ------- ---------- ------ ---------- ------ AWI233-5 69°23.73'S 1916 20-12-0 ULS 42 191 725 00°04.04'W 16:00 ACM 1569A 220 (1) AVT 9186 717 725 ACM-CTD 1387A 1873 725 AWI232-5 68°59.49'S 3337 21-12-00 ULS 46 166 724 00°02.18'W 16:00 ACM 1565A 225 (1) AVTCP 9214 732 5(2) AVT 9182 1778 724 ACM-CTD 1447A 3284 724 AWI231-4 66°30.00'S 4515 23-12-00 ULS 47 179 724 00°01.80'W 10:00 ACM-CTD 1456A 198 (1) CT 237 250 724 CT 238 300 724 CT 239 350 724 CTD 245 400 724 CT 240 450 724 CT 435 500 724 CT-P 1231 550 (3) CTD 247 600 724 CT-P 1232 650 724 ACM-CT 1442A 705 724 AVT 10003 1811 724 ACM-CTD 1472A 4472 (1) AWI230-3 66°00.34'S 3447 23-12-00 ULS 36 170 724 00°10.38'E 20:00 ADCP 1600 187 (4) AVTP 9204 195 724 CT 236 295 724 CTD 243 395 724 CTD 244 495 724 CT-P 1230 595 724 ACM-CTD 1474A 705 724 AVT 9785 1598 724 ACM-CTD 1470A 3404 (1) AWI229-4 63°57.86'S 5167 26-12-0 ULS 24 127 713 00°02.40'E 18:00 ACM-CTD 1450A 170 (1) CT 228 220 713 CT 230 270 713 CT 232 320 713 CTD 241 370 713 CT 233 420 713 CT 235 470 713 CT-P 1288 520 713 CTD 242 570 713 CT-P 1229 620 713 ACM-CTD 1443A 677 713 AVT 9391 1973 74(2) ACM-CTD 1451 5117 (1) AWI227-7 59°04.20'S 4620 29-12-00 ULS 08 148 (4) 00°04.40'E 14:00 AVTCP 9194 252 707 AVTCP 9998 679 707 SBE16 2422 680 637 AVT 9179 1986 707 AVT 9211 4596 707 SBE16 631 4597 (4) AWI228-5 56°57.61'S 3712 30-12-00 ACM 1553A 205 (1) 00°01.40'E 16:00 SBE16 2416 206 551 Micro-J 1324F 256 411 CT-P 1235 306 704 CT 224 356 704 AVTP 10541 413 704 SBE16 630 414 (4) SBE16 319 575 (4) AVT 9180 741 704 CT 229 742 704 CT-P 1603 992 704 CT-P 1604 1242 704 AVT 9190 1948 704 RCM11 20 3649 704 SBE26 227 3712 (4) AWI238-3 54°30.60'S 1700 31-12-00 ACM 1567A 176 701 00°0170'E 16:00 SBE16 2415 187 625 CT 231 227 701 CT-P 1234 327 701 AVTP 9193 383 701 SBE16 1167 384 701 CT-P 1237 550 701 AVTP 10926 730 701 SBE16 1979 731 697 CT-P 1605 981 701 CT-P 1606 1231 701 RCM11 25 1610 701 SBE26 228 1700 (4) AWI239-2 52°00.66'E 2460 03-01-01 ACM 1558A 218 697 00°00.93'E 02:00 SBE16 2414 219 496 CT-P 1233 269 697 CT 216 319 697 CT 225 369 697 AVTP 10927 426 697 SBE16 1977 427 566 CT-P 1236 597 697 AVTP 10928 773 697 SBE16 1978 774 584 CT-P 1607 1024 697 CT 269 1274 697 AVTP 12325 1780 697 CT 227 1781 697 RCM11 26 2407 697 SBE26 276 2460 697 Remarks: Instrument failure no data recorded; Instrument flooded = data lost; Instrument lost during recovery; Memory download failed, has to be done by manufacturer. Table 2.8-2: Moorings deployed at the Prime Meridian and sound source mooring northeast of Maud Rise. 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; SBE16P# = Seabird Electronics SBE16 recording temperature, conductivity, and pressure; here P# indicates the pressure range e.g. P1 for 1000 psi; ULS Christian Michelsen Research Inc. upward looking sonar to measure the sea ice draft; SBE26 = Seabird Electronics SBE26 bottom pressure recorder: SBE37-Seabird Electronics SBE37 recording temperature and conductivity, SBE37Pu = Seabird Electronics SBE37 recording temperature and conductivity with external pump; SBE37PuP# = Seabird Electronics SBE37 recording temperature, conductivity, and pressure with external pump; here P# indicates the pressure range e.g. P1 for 1000 psi; SQ-Sound source for SOFAR-Drifters. Date Water time Latitude depth of 1st Instrument Serial Instrument Mooring Longitude (m) record type number depth (m) -------- ---------- ----- ------- ---------- ------ ---------- AWI233-6 69°23.66'S 1948 15-12-02 ULS 49 165 00°03.98'W 22:48 AVTP 8367 237 AVTCP 8395 738 SBE37 1604 1891 AVT 10499 1892 AWI232-6 68°59.87'S 3369 16-12-02 ULS 50 175 00°00.32' E14:46 AVTP 11887 252 AVTPV 8396 765 AVT 10498 1809 SBE37 1605 3314 RCM11 127 3315 AWI231-5 66°30.56'S 4552 18-12-02 ULS 39 178 00°02.03'W 10:55 AVTCP 8400 220 S3E37 2609 220 SBE37 211 270 SBE37 2610 320 SBE37 214 370 SBE37 215 420 SBE37Pup3 2392 470 SBE37 220 520 S8E37 222 570 SBE37 223 620 S3E37 2234 670 SBE37Pu 2382 720 AVTCP 9215 731 SQ 18/W2 882 AVT 9768 1837 SBE37Pu 2383 4492 RCM11 133 4498 AWI230-4 66°00.30'S 3477 18-12-02 ULS 38 177 00°10.29'E 20:53 AVTCP 8401 220 SBE37Pu 2384 220 SBE37Pu 2385 320 SBE37P3 249 420 SBE37 445 520 SBE37 446 620 SBE37Pu 2386 720 AVTCP 9995 731 RCM11 134 1627 SBE37Pu 2087 3427 RCM11 135 3433 AWI227-8 59°0420'S 4566 07-12-02 ULS 41 162 00°04.47'E 09:01 AVTCP 10004 274 AVT 3570 704 SBE37PuP3 2395 705 AVT 10503 2011 SBE37Pu 2091 4616 RCM11 146 4622 AWI229-5 63°57.23'S 5200 10-12-02 ULS 38 1471 00°00.21'W 18:45 AVTP 8402 193 5BE37P3 2387 200 SBE37 250 250 SBE37 448 300 SBE37 449 350 SBE37Pu 2086 400 SBE37PuP 23933 450 SBE37P 2088u 500 SBE37P 2089u 550 SBE37P 2090u 600 SBE3 26117 700 SBE37PuP 15647 750 AVT 9783P 704 S 14/W1Q 659 RCM1 1441 2005 SBE37P 2388u 5150 RCM1 145 5156 AWI228-6 56°57.64'S 3699 04-12-02 AVTCP 8405 190 00°01.62'E 23:00 SBE16P1 19783 191 SBE37PuP3 2235 241 SBE37Pu 2092 291 SBE37Pu 2093 341 AVTCP 9201 402 SBE37Pu 2391 403 SBE37PuP3 2396666 562 AVT 9389 728 SBE37Pu 2094 729 SBE37Pu 2095 979 SBE37PaP7 1565 1227 RCM11 100 1934 RCM11 101 3635 SBE37Pu 2389 3636 SBE26 276 3699 AWI238-4 54°30.63'S 1718 03-12-02 AVTP 11892 187 00°01.81'E 14:20 SBE16P3 2420 188 SBE37Pu 2096 238 SBE37Pu 2097 288 SBE37Pu 2098 338 AVTP 10491 399 SBE37FuP3 2236 400 SBE37Pu 2099 570 AVT 9390 745 SBE37PuP3 2237 746 SBE37Pu 2100 1000 SBE37Pu 2101 1250 RCM11 102 1651 SBE37Pu 2390 1652 SBE26 257 1718 AWI239-3 53°00.49'S 2483 02-12-02 AVTCP 8419 240 00°01.96'E 18:03 SBE37Pu 2231 241 SBE37Pu 2102 291 SBE37Pu 2103 341 SBE37Pu 2104 391 AVT 9401 441 SBE37PuP3 2394 442 SBE37Pu 2105 613 AVT 9458 797 SBE37PuP3 2238 798 SBE37Pu 2233 1043 SBE37PuP7 1566 1293 RCM11 103 1793 SBE37 2232 1804 RCM11 104 2429 SBE26 261 2483 AWI240-1 64°30.00'S 5200 SQ new 856 10°00.00'E Table 2.8-3: Deployment of ARGOS transmitters on icebergs. ARGOS Date and time of Iceberg Digital identi- - deployment Latitude dimension photo fication - last position Longitude L-W-H (m) Remarks (JPG) -------- ---------------- ---------- ----------- --------------- ------- 9360 11-12-02 / 11:36 65°57.15'S 200-200-25 inclusive air EB1 13-01-03 / 12:00 02°28.89'W pressure sensor 14959 13-12-02 / 15:09 70°20.88'S 1600-750-40 tritium snow EB2 10-01-03 / 12:00 08°20.44'W sample taken 14958 13-12-02 / 15:30 70°13.61'S 380-380-25 tritium snow EB3 10-01-03 / 12:00 07°57.00'W sample taken 14960 14-12-02 / 12:54 70°16.63'S 380-380-40 tritium snow EB4 11-01-03 / 12:00 09°39.85'W sample taken 14956 16-12-02 / 13:25 69°06.05'S 380-380-20 tritium snow EB5a 12-01-03 / 12:00 00°29.81'E sample taken EB5b 8056 18-12-02 / 13:56 66°07.24'S 180-180-10 inclusive air EB6a 13-01-03 / 12:00 00°24.79'E pressure sensor EB6b 14955 19-12-02 / 09:30 64°52.09'S 180-180-50 tritium snow EB7 22-12-02 / 12:00 00°16.97'E sample taken 9835 23-12-02 / 09:00 64°01.33'S 200-100-15 inclusive air EB8a 10-01-03 / 12:00 08°17.02'E pressure sensor EB8b capsized EB8c 14954 29-12-02 / 15:25 69°10.98'S 100-300-30 tritium snow EB9a 12-01-03 / 12:00 22°32.06'E sample taken EB9b 14961 29-12-02 / 16:09 69°24.07'S 300-300-35 Tritium snow 12-01-03 21°34.69'E sample taken Table 2.8-4: PIES mooring positions. Times are set according to GPS time, which was 14 S late (GPS = UTC + 14 s) relative to UTC during this period. Identifiers Start Launch Auto release wt. Depth (m) AWI project - date (DMY) - date - Hydroswe. Latitude Date/ Time Speed URI SN. - time (GPS) - time - PODAS Longitude (UTC) (km/h) ----------- ------------ ------------ ------------- ---------- ---------- ------ PIES-1 26-11-02 26-12-06 4610 44°39.75'S 27-11-02 1.9 67 18:46:37 20:00 4613 07°05.03'E 16:42 PIES-2 28-11-02 26-12-06 3879 50°15.01'S 29-11-02 2.5 69 16:09:55 20:00 3930 01°25.00'E 21:56 Table 2.8-5: ARGOS/APEX profiling float setting positions during ANT-XX/2. All floats feature an ice avoidance software feature, based on measurement of the median temperature between 50 and 20 m water depth. Float times are set according GPS time which was 14 slate (GPS = UTC + 14 s) relative to UTC during this period. Float number Start Launch ----------------------- -------------- ---------------------------------------- Webb Wt. Date AWI ARG ARG Res Date-GPS Depth Latitude Time Wave Wind Ice HEX DEC SN Time-UTC (m) Longitude (UTC) height (m/s) cov --- ----- ----- --- -------- ----- ---------- -------- ------ ----- --- 40 90C64 25649 673 09-12-02 5337 62°37.84'S 09-12-02 0 13 5 09:04:08 00°05.81'W 15:32 41 9F3F1 26575 680 16-12-02 4512 68°00.28'S 17-12-02 0 2 5 16:33:12 00°03.49'W 03:44 42 A1965 26725 681 18-12-02 3757 65°00.32'S 19-12-02 0 5 4 22:48:06 00°00.41'W 11:13 43 A9096 10818 655 21-12-02 5172 62°57.27'S 22-12-02 1 5 0 08:26:04 05°16.46'E 09:54 44 90C91 25650 674 23-12-02 5214 64°29.48'S 23-12-02 0 9 1 08:31:53 09°49.45'E 15:43 45 91DC7 25719 675 25-12-02 3424 66°03.46'S 25-12-02 0 2 3 14:59:45 14°32.98'E 23:07 46 93890 25826 676 27-12-02 4045 67°59.98'S 28-12-02 0 5 2 16:26:23 20°13.58'E 13:33 47 95178 25925 677 06-01-03 4899 65°49.57'S 06-01-03 0 2 0 18:02:00 17°45.57'E 20:12 48 9F3A2 26574 679 08-01-03 5055 64°07.90'S 08-01-03 0 4 0 10:18:32 20°45.40'E 13:23 49 9518D 25926 678 09-01-03 5160 61°59.96'S 09-01-03 0 4 0 19:30:00 22°58.95'E 22:45 Table 2.8-6: RAFOS float setting positions. Float times are set according to GPS time, which was 14 s late (GPS + 14 s) relative to UTC during this period. Float number Start Launch ---------------------------------- ----------------- -------------------------------------- Dive start Water Date AWI ARGO ARG Sea Start Date Expected Depth Latitude Time Wave Wind Ice HEX DEC Scan time GPS surf. date (m) Longitude (UTC) ht (m/s) cov --- ----- ---- ---- ---------- ---------- ----- ---------- -------- ---- ----- --- 01 4938F 4684 262 17-12-02 18-12-02 3497 66°00.27'S 18-12-02 0 0 7 14:52 16-02-04 00°10.30'E 20:28 02 49755 4701 263 17-12-02 18-12-02 3960 65°29.90'S 19-12-02 0 0 5 14:38 16-02-04 00°00.10'E 04:34 03 5FOEB 6083 270 16-12-02 17-12-02 3758 65°00.31'S 19-12-02 0 5 4 18:50 17-02-04 00°00.36'E 11:13 04 498F0 4707 264 17-12-02 18-12-02 4670 64°30.36'S 20-12-02 0 4 4 18:31 16-02-04 00°00.40'E 00:04 05 49E14 4728 265 17-12-02 18-12-02 5200 64°00.18'S 20-12-02 0 6 0 18:21 16-02-04 00°00.30'E 03:04 06 49E47 4729 266 20-12-02 21-12-02 5414 62°33.87'S 22-12-02 2 8 0 18:12 17-02-04 04°11.42'E 03:22 07 49EE1 4731 268 21-12-02 22-12-02 5383 63°17.97'S 22-12-02 1 3 0 10:13 16-02-04 06°15.10'E 18:43 08 5F101 6084 271 21-12-02 22-12-02 4926 63°43.23'S 23-12-02 0 5 3 15:37 16-02-04 07°32.18'E 02:05 09 49F0B 4732 269 22-12-02 23-12-02 5028 64°07.30'S 23-12-02 0 8 2 08:42 17-02-04 08°38.93'E 09:22 Table 2.8-7: Position of sound source moorings. Identifiers Start Deployments -------------------------------- ----- ----------------------------------------- Sound Ping Water AWI source Electr. AWI time Depth Latitude Date UTC Wave Wind project SN SN mooring (GPS) (m) Longitude Time UTC height (m/s) ------- ------ ------ ------- ----- ----- ---------- -------- ------ ----- W1 49 14 229-5 00:35 5200 63°57.23'S 10-12-02 0 13 00°00.21'W 18:45 W2 19 19 231-5 01:05 4542 66°30.56'S 18-12-02 0 5 00°02.03'W 10:41 W3 21 21 240-1 01:35 5173 64°29.49'S 23-12-02 0 9 09°49.53'W 15:40 2.9 TRACER MEASUREMENTS Hendrik Sander and Martha Schattenhofer CFCs and Tritium are transient tracers of anthropogenic origin. Measured distributions of these tracers provide information on the renewal of subsurface water from the ocean surface layer on decadal time scales. Sections on the Greenwich Meridian investigated during ANT-X/4 (1992), ANT-XIII/4 (1996) and ANT-XV/4 (1998) were repeated to evaluate the increase of the tracer concentrations in time. The comparison between the atmospheric and the in-situ increase will be used to study transport processes. In addition new sections in the east will provide information of the inflow from the east into the Weddell Sea. All samples taken during the cruise will be analyzed in the laboratory after the cruise. The waters samples for CFCs were taken from the rosette water sampler and were stored in flame-sealed ampoules for later analysis. Along the Greenwich Meridian 36 stations were sampled, along the section between 0° and the GeoBox thirteen stations, in the GeoBox six stations and along 23°E 14 stations. Overall 1007 water samples for CFCs were taken. They will be extracted after the cruise and analyzed with a mass spectrometer. Snow samples for tritium measurements were taken at 25 locations along the entire cruise. This includes eight samples from icebergs, four samples from the shelf-ice and thirteen samples from ice floes. All gases will be extracted from the Tritium samples which will then be stored or half a year. After this time a sufficient amount of Tritium will have decayed to 3He and can be measured by the mass spectrometer. This will help to improve the global Tritium input function and give more details about the local precipitation. 2.10 NATURALLY OCCURRING RADIONUCLIDES AS TRACERS FOR WATER MASS CHARACTERIZATION Claudia Hanfland, Walter Geibert, Ingrid Vöge and Olaf Boebel Natural radioactivity in the oceans originates mainly from three sources: cosmogenic nuclides, 40K and decay products of the naturally occurring decay chains 238U, 235U and 232Th, Especially isotopes of the latter find a wealth of applications in the study of oceanic reaction and transport processes taking place on time scales from hours and days to years. According to their geochemical behaviour in sea water, the radionuclides can be grouped after their respective particle-reactivity. For example, given, radium and actinium tend to stay in solution while thorium or protactinium are quickly scavenged by particles and subsequently transported to the seafloor. Disequilibria between parent and daughter nuclides are the consequence of this partitioning. While particle transport processes are investigated by means of adsorption-prone isotopes, water mass studies rely on elements having a soluble behaviour. The supply of the rather mobile elements to the water column is mostly by diffusion from sediments through decay from a particle- reactive parent while their distribution in the water column is governed by their respective half-lives. During expedition ANT-XX/2, 234Th, 226Ra, 228Ra and 227Ac have been sampled in surface waters and on selected vertical profiles. 234Th has been measured in order to estimate the export production from the upper water column into deeper water layers and will be presented in further detail in the chapter 2.11.5. SYNPART Project. 226Ra AND 228Ra SAMPLING PROGRAM Both 226Ra and 228Ra (half-lives 1600 yrs and 5.5 yrs, respectively) are released to the water column from the sediment through decay of thorium isotopes, but in consequence of a difference in parent distribution and half-life, the release of 226Ra is strongest from deep-sea sediments while 228Ra accumulates to high activities in shallow water regions. Sampling for 226Ra has been carried out with regard to two objectives: (1) the quantitative determination of 226Ra provides a simple means to convert 226Ra/228Ra activity ratios into absolute 228Ra activities (see below). (2) It is the most abundant of the radium isotopes in open ocean waters and is best suited to study the biogeochemistry of radium in the marine environment, i.e. its behaviour as a biointermediate element. Radium has been considered as a water mass tracer with a nutrient-like distribution (Broecker et al. 1967). Based on the similarity of vertical water column profiles of 226Ra and Si, it was hypothesized that siliceous tests act as a main carrier phase for 226Ra (Ku et al. 1970, Ku & Lin 1976). Given the pre-dominance of diatoms over other phytoplankton species in the Southern Ocean, the relation should hold especially in circumpolar waters. However, results from previous cruises have indicated that the uptake of 226Ra continues north of the Polar Front after the near depletion of Si, pointing to a decoupling of both parameters. Besides the sub sampling necessary for the 228Ra analysis, 226Ra was sampled on three selected vertical water column profiles (Figure 2.10-1) in conjunction with nutrient analysis in order to get a better idea of the biogeochemical processes governing the distribution of 226Ra in southern circum polar waters. 228Ra has been used widely (e.g. Kaufmann et al. 1973, Reid et al. 1979, Moore et al. 1986, Rutgers van der Loeff et al. 1995) as a tracer for prolonged contact of water masses with continental shelf areas. It is a daughter product of 232Th, which is common in most sediment types but nearly absent in sea water due to its particle reactive behaviour. In contrast, radium is soluble in sea water and can accumulate to high activities over fine-grained sediment. According to its half-life of 5.8 years, the activity of 228Ra will decrease with distance from the source and is extremely low in the open ocean. Dependant on the geographic region, the sampling for 228Ra during ANT-XX/2 was performed under different aspects (Figure 2.10-1): Figure 2.10-1: sampling chart for radium and actinium during ANT-XX/2. Numbers refer to official stations, full labeling should read: PS63-xxx. Polar Frontal Region In the context of iron as a growth-limiting factor for the primary productivity of the Southern Ocean, the oceanic fronts within the Antarctic Circumpolar Current (ACC) and especially the Polar Front have been suggested as effective transport mechanisms for iron released from continental shelf sediments and transported eastwards with ACC (de Baar et al. 1995, Löscher at al. 1997). If the shelf areas represent indeed important source areas of iron for the open South Atlantic, this should be mirrored by increased 228Ra activities. Results from previous cruises indicate an ambiguous picture, pointing to rather sporadic inputs that are highly variable in both space and time. Hence, high resolution sampling of the Polar Frontal Region along 0° and 23°E was done in order to get a better picture of the variability of possible shallow water inputs with the Polar Front. South-Eastern Weddell Gyre Inflow of North Atlantic Deep Water into the Weddell Gyre takes place in its southeastern corner (Orsi et al. 1993), a region where currently only very few natural radionuclide data are available for (Geibert et al. 2002, Hanfland 2002). The determination of 228Ra will help to demarcate the extension of coastal waters into the Weddell Gyre. Agulhas (Return) Current Intense mixing of subtropical and subantarctic water masses takes place in the region south of South Africa. Occlusion of the retroflecting Agulhas Current generates rings that move northwestwards into the Atlantic while perturbations in the flow of the Agulhas Current lead to the spawning of both cyclonic and anticyclonic eddies (Lutjeharms 1996, Boebel et al. 2003). The mixing waters carry very distinct 228Ra signals, a feature that should help especially in a better distinction of the origin of cyclonic eddies. While waters moving north from the Antarctic zone are typically low in 228Ra, cyclones developing along the South African coast in the course of a Natal Pulse can be expected to carry a strong coastal signal. Four stations had been sampled for 228Ra within the Aguihas Retroflection Area (Figure 2.10-2): PS 63-182. cyclonic eddy PS 63-197: Agulhas Retroflection PS 63-199: cyclonic eddy PS 63-216: Agulhas ring A highly variable, mesoscale flow field dominates the Agulhas Region. To obtain samples as close as possible to the end-members of each regime, an identification of these mesoscale features during the cruise was mandatory. Using steric sea-surface height anomalies (SSH data) from MODAS (Modular Ocean Data Assimilation System), the location of cyclones and anticyclones was achieved in real-time. Daily MODAS SSH fields were uploaded to RV POLARSTERN by the Stennis Space Center at the Naval Research Lab, Mississippi in real time. MODAS-SSH data have recently been shown to provide a highly reliable view of the overall distribution of the mesoscale flow field (Boebel & Barron 2003) in this region. Modulations in the SSH field are directly related to ocean currents, which flow along SSH isolines with higher SSH values to their left when looking downstream (Figure 2.10-2). Figure 2.10-2: Steric sea-surface height (SSH) from MODAS from January 18, 2003. Similar plots were produced for each day and the cruise track adjusted as to sample the water in each feature's centre. The reliability of the actual MODAS SSH fields was tested during the cruise by monitoring the depth of the 10°C isotherm. The latter should be located at depths around 800 m when an anticyclone is traversed, or alternatively, at 300-500 m when encountering cyclones. This was indeed the case when XBT casts succeeded, though between P563-197 and PS63-199 only few XBT profiles were collected due to bad weather. Figure 2.10-2 shows the situation on January 18, 2003. The first eddy sampled near 40°37'S (PS63-182) shows a local SSH minimum and hence represents a cyclonic circulation pattern, which we traced back in time to a subantarctic origin. PS63-1, on the other hand, is located at the local SSH maximum indicative of the Agulhas Retroflection proper. A cyclone north of the Agulhas Retroflection might have subantarctic (Atlantic) or subtropical/Indian origin (a Natal Pulse) or might have been formed locally (Boesel et al. 2003). One such cyclone has been probed during PS63-199. In contrast to the previous two locations, this feature is not expected to display end-members but a mix of Indian and Atlantic water types. The same holds true for the last station in a matured Agulhas Ring (anticyclone) sampled during PS63-216. While travelling north, these features have been shown to entrain surrounding waters, which could be of subantarctic and/or subtropical origin. 227Ac SAMPLING PROGRAM 227Ac (half-life 21 yrs) is almost exclusively released from deep-sea sediments into bottom waters. Any excess activity over its parent nuclide 231Pa in the upper water column indicates rapid upwelling of deeper water masses (Geibert et al. 2002). Sampling for 227Ac at the sea surface follows the same procedure as described for 228Ra (see below). Determination of the 227Ac activity will be done on all surface water samples in the Weddell Gyre and on the vertical stations PS63-64, PS63-83 and PS63-121. The combined analysis of 227Ac and 228Ra will allow a better distinction of deep upwelling versus lateral input of water masses in the southeastern Weddell Gyre. Additional sampling Samples for the determination of 231Pa and 230Th in the water column were taken on three selected vertical profiles. These samples will be analyzed by the University of Kiel (group Scholten/Fietzke). Additionally, three samples of Weddell Sea Deep Water were taken for the analysis of the isotopic composition of Cadmium (analysis by Rehkamper, ETH Zürich). Methods 226Ra 20 l of sea water were taken either directly from the ships sea water supply or sampled from the CTD. Surface water samples were run through a 1µm-prefilter to remove particulate matter. Particle concentrations from samples taken below the mixed layer were so low that filtering was not necessary. The samples were then weighed to determine the sample size. Even in rough seas, this is accurate to at least 100 g which equals an error of 0.5% for 20 kg. A pre-weighed aliquot (100 ml) of a BaCl2-solution that had been prepared before the cruise was added under constant stirring to every 20 l water sample to precipitate radium as Ba(Ra)SO4, making use of the natural sulfate content in sea water. After at least one hour of further mixing on the magnetic stirrer, the crystals were recovered by decantation and centrifugation and washed several times to remove any interfering ions. At home, the dried and weighed precipitates will be filled in plastic tubes, sealed and set aside for about three weeks to allow the short-lived daughters 214Pb and 214Bi to grow into equilibrium with their parent 226Ra. After establishment of a secular equilibrium, the sample will be counted by γ-spectrometry. 228Ra and 227Ac sampling was performed with MnO2-coated cartridges that had been prepared before the cruise by immersion overnight at 70°C in a bath of a saturated KMnO4 solution. The radionuclides get adsorbed on the MnO2-coating. For surface water samples, a filter system was connected to the ship's sea water supply. The water sample was run through an uncoated cartridge (1 µm) for removing particulate matter, two MnO2-coated cartridges put in series and a flowmeter for recording the sample volume. Typical sample volumes were between and 3 m3. Sampling on vertical water profiles was performed with six time-programmed pumping units, equally loaded with a prefilter and two coated cartridges. The pumps were let on depth for 2.5 hrs and filtered about 1 m3 of sea water. In the home lab, the coated cartridges will be rinsed with deionised water and dried. Further processing of the samples involves acid-leaching of the cartridges, separation of the different isotope fractions by repeated precipitation and ion-exchange chromatography and determination of the respective activities by alpha- or gammaspectrometry. Due to their extremely low activities, 228Ra and 227Ac will be analyzed via their daughter-nuclides 228Th and 227Th, respectively (Moore 1972, Li et al. 1980, Geibert 2002). As the adsorption of radionuclides on cartridges is seldom quantitaive, the results must be corrected for their efficiency (E). For 228Ra, the cartridges yield 228Ra/226Ra activity ratios that are converted to absolute 228Ra activities by means of the 226Ra subsamples. 227Ac is determined by using the cartridge formula: E = 1 -B/A, where A and B are the two cartridges put in line (Rutgers Van Der Loeff & Moore 1999). For the determination of 227Ac activities on depth profiles, it was planned to use a delayed coincidence counter system (Moore & Arnold 1996). However, when in operation on board, the counting unit proved to have several substantial problems. First, the manganese adsorbers dried within about half an hour, with the effect of large changes in counting efficiency. The counting of test samples showed additionally intervals of increased background activity. These intervals were irregular in time, and the activity too variable to allow reliable counting of the samples. Therefore, a different method of sampling was applied. To the water samples (12-60 l) NH4OH, KMnO4, and MnCl2 were added in small amounts to produce a MnO2 precipitation that adsorbs 227Ac quantitatively. Later, the precipitate was filtered onto 142 mm diameter polycarbonate filters with 1 µm pore size. 234Th was counted on the filters as a yield tracer for the MnO2. Back in the home lab, the samples containing the 227Ac will be dissolved, purified and counted via the more sensitive γ-spectrometric method. REFERENCES Boebel, O. & Barron, C. (2003): A comparison of in-situ float velocities with altimeter derived geostrophic velocities.- Deep-Sea Res. II, 50; 119-139. Boebel, O., Lutjeharms, J., Schmid, C., Zonk, W., Rossby, T. & Barron, C. (2003): The Cape Cauldron: A regime of turbulent inter-ocean exchange.- Deep-Sea Res. II, 50:57-86. Broecker, W.S., Li, Y.-H. & Cromwell, J. (1967): Radium-226 and radon-222: concentration in Atlantic and Pacific Oceans.- Science 158: 1307-1310. de Baar, H.J.W, de Jong, J.T.M., Bakker, D.C.E., Löscher, B.M., Veth, C., Bathmann, U. & Smetacek, V. (1995): Importance of iron for plankton blooms and carbon dioxide drawdown in the Southern Ocean. Nature 373: 412-415. Geibert, W., Rutgers van der Loeff, M.M., Hanfland, C. & Dauelsberg, H.-J. (2002); 227-Actinium as a deep-sea tracer: sources, distribution and applications.- Earth Planet. Sci. Lett. 198: 147-165. Hanfland, C. (2002): Radium-226 and Radium-228 in the Atlantic Sector of the Southern Ocean.- Ber. Polarforsch. Meeresforsch. 431: 1-135. Kaufman, A, Trier, R.M. & Broecker, W.S. (1973): Distribution of 228Ra in the World Ocean.- J. Geophys. Res. 78: 8827-8848. Ku, T.-L. & Lin, M.C. (1976): Ra-226 distributions in the Antarctic Ocean.- Earth Planet. Sci. Lett. 31: 236-248. Ku, T.-L., Li, Y-H, Mathieu, G.G. & Wong, H.K. (1970): Radium in the Indian-Antarctic Ocean South of Australia.- J. Geophys. Res. 75: 5286-5292. Li, Y-H, Feely, H.W & Toggweiler, J.R. (1980): 228Ra and 228Th concentrations in GEOSECS Atlantic surface waters.- Deep-Sea Res, 27A: 545-555. Löscher. B.M., de Baar, H.J.W., de Jong, J.T.M., Veth, C. & Dehairs, F. (1997): The distribution of Fe in the Antarctic Circumpolar Current.- Deep-Sea Res. II, 44; 143-187. Lutjeharms, J.R.E. (1996): The Exchange of Water Between the South Indian and South Atlantic Oceans.- In: G. WEFER, W.H, BERGER, G. SIELDER & D.J. WEBB (Eds.), The South Atlantic: Present and past circulation, Springer Verlag, Berlin, 125-162. Moore, W.S. (1972): Radium-228: Application to thermocline mixing studies.- Earth Planet. Sci. Lett. 16: 421-422. Moore, W.S. & Arnold, R. (1996): Measurement of 223Ra and 224Ra in coastal waters using a delayed coincidence counter.- J. Geophys. Res. 101 (C1): 1321-1329. Moore, W.S., Sarmiento, J.L. & Key, R.M. (1986): Tracing the Amazon component of surface Atlantic water using 228Ra, salinity arid silica.- J. Geophys. Res. 91(C2): 2574-2580. Orsi A.H., Nowlin Jr., W.D. & Whitworth III, T. (1993): On the circulation and stratification of the Weddell Gyre. - Deep-Sea Res. I, 40: 169-203. Reid, D.F., Moore, W.S. & Sackett, W.M. (1979); Temporal variation of 228Ra in the near-surface gulf of Mexico.- Earth Planet. Sci. Lett. 43: 227-236. Rutgers van der Loeff, M.M., Key, R.M., Scholten, J., Bauch, D. & Michel, A. (1995); 228Ra as a tracer for shelf water in the Arctic Ocean.- Deep-Sea Res. II, 42: 1533-1553. Rutgers van der Loeff, M.M. & Moore, W.S. (1999); Determination of natural radioactive tracers.- In: K. GRASSHOFF, K. KREMLING AND M. EHRHARDT, M. (Eds.), Methods of Seawater Analysis. 365-397, Wiley-VCH, Weinheim. 2.11 GEOSCIENTIFIC INVESTIGATIONS 2.11.1 BATHYMETRIC INVESTIGATIONS IN THE EASTERN WEDDELL SEA Sonja Gütz, Alexander Iffland and Anton Obermüller During cruise ANT-XX/2 of RV POLARSTERN the swathsonar system Hydrosweep was used to obtain new bathymetric data from the Larazev and Riiser-Larsen seas. Another important goal for the bathymetry group was to support the other projects especially physical oceanography and marine geology by supplying informations on detailed morphological sea floor structures and updated working charts (Figure 2.11-1). For physical oceanographers several mooring stations surveys were carried out to add necessary information on the ocean seafloor topography. The obtained depth and morphological information is an important prerequisite for the interpretation of current behaviour at mooring stations and fundamental for further station planning before deploying a new mooring. Therefore, collected data were visualized together with previously gathered data sets in large-scale charts and provided for planning activities. Figure 2.11-1: Trackplot of the collected Hydrosweep data during ANT-XX/2 The main area of geological interest during this expedition was the "GeoBox" covering the area between 62-70°S and 13-26°E. Within this area a channel system in the southern Riiser-Larsen Sea was main objective to "partly" systematic measurements. The spatial depth data collected with the swathsonar system were used to correlate with the information retrieved from the measurements by the sedimentsonar Parasound and to identify appropriate locations for sediment sampling. At these sites gravity corer and multicorer were deployed. Finally all "partial" surveys of the Hydrosweep swathsonar system contributed to add more accurate data to the poor data density in the Southern Oceans and to enlarge the range of data available for international bathymetric charts such as the GEBCO (General Bathymetric Chart of the Oceans) and the AWI BCWS (Bathymetric Chart of the Weddell Sea). Most of the measurements have - with respect to areal coverage - to be considered "partly or partially" because due to obligations by the German Federal Environmental Agency (UBA), the Hydrosweep system had to be shut down south of latitude 60°S when marine mammals (i.e. whales and seals) were identified or sighted within a range of 3 km around the vessel. Not before 20 minutes after the last sighting of a marine mammal, the Hydrosweep system could be re-started with a "soft start procedure" in order to avoid harming of marine mammals in the vicinity of the vessel, According to this "procedure", energy was increased over a time period of one hour until full measurements and data acquisition were possible. Technically this "soft start procedure" was subdivided in three separate steps, each of them lasting for 20 minutes. With each step the emitted intensity was slowly increased. Step 1 was a shallow water search mode with a swath width of 200, Step 2 was a shallow water mode with a 1200 swath width and Step 3 was already a deep sea mode with 90° swath width but alternating directions. The full measurement mode of the system was reached not earlier than one hour and 20 minutes after the last sighting of a mammal. Due to these obligations (and restrictions) south of 60°S profiling was very incomplete and as a result areal data coverage was poor as demonstrated at Althoff Seamount. Earlier cruises in 1990 and 2000 discovered a rapidly changing seafloor and rough bottom topography in the waters at 66° to 66°30'S and 16° to 17°E. This led to the assumption of the existence of a larger seamount in that particular area. During ANT-XX/2, therefore, it was planned to carry out a more complete survey of these waters to get a better idea of extend, height and structural position of this feature. Approaching the area several whales were sighted and consequently the swath and sediment penetrating sonar systems (Hydrosweep and Parasound) had to be shut down. Only a single line crossing the structure could be obtained by the DWS echosounder revealing an approximate idea of the structure of this feature (Figure 2.11-2). However, for any more precise scientific interpretation a three dimensional spatial representation is needed, which can only be achieved by multibeam surveys. Nevertheless, by its general outline this feature was classified a seamount and named in April 2003 at a meeting of SCUFN (GEBCO Sub-Committee on Undersea Feature Names) "Althoff Seamount" after Friedrich Althoff (*19/2/1839 †20/10/1909). Althoff was a lawyer and later a Prussian politician for culture and science during the period of 1882-1907 with extraordinary efficacy. He was a professor for civil law before joining the Prussian Ministry for Culture where he became the director in 1897 Althoff was an active promoter or the expansion of German universities and scientific institutions. He focused his energy especially on the famous Valdivia expedition in 1899 which led into the southern Atlantic Ocean. During this expedition, among others, Bouvet Island was discovered. Figure 2.11-2: Topographic map of the Althoff Seamount above and the crossprofile (bottom) 2.11.2 SEDIMENT CHARACTERIZATION BY ECHOSOUNDING AND SAMPLING Gerd Kuhn, Sylvia Brückner, Claudia Didié, Matthias Forwick, Christian Hass, Norbert Lensch, Wolfgang Schmitt, Constanze v, Waldthausen and Thomas Wittling The reconstruction of the paleoclimatic and paleoceanographic development of the late Quaternary Southern Ocean and adjacent continental areas in high temporal and spatial resolution is a main goal of our long-term study. During ANT-XX/2 the sedimentary budget of biogenic and terrigenous components and their variability was investigated in cooperation geochemical projects. Main objectives were the relationships between production of biogenic components and input of terrigenous components and involved nutrients. Therefore in addition to surface samples long sediment cores were recovered on the transects across the Polar Frontal Zone (Table 2.11-1) for the following projects: • Establishment of a high resolution stratgraphy of the obtained sediment sectons (isotope stratigraphy, AMS-14C age determinations, magnetic susceptibility), • Quantification and reconstruction of terrigenous sediment supply and its distribution by paleocurrents (high-resolution granulometry, bulk and clay mineralogy, heavy minerals, geochemical tracers), • Identification and quantification of biogenic and terrigenous components and their variation during glacial and interglacial, periods. • Correlation of the marine sedimentary record with Antarctic ice core records and reconstruction of paleoenvironmental conditions. The ship-mounted Parasound system (Krupp Atlas Electronics, Bremen, Germany) is a sub-bottom echosounder. It generates two primary sound waves at frequencies of 18 kHz and of 20.5-23.5 kHz. As a result of the parametric effect, a secondary frequency between 2.5 and 5.5 kHz is produced at a very narrow angle of 4°. This provides much higher horizontal resolution at a penetration depth comparable to that of other sediment-echosounding devices. The Parasound device is attached to an analogue printer (Atlas DESO 25). The analogue signal is then digitised and post-processed using the PC-based Paradigma software (Spiess 1993). Digital data are stored on hard disk (later on CD) and printed simultaneously on a colour printer. Important data such as time, geographic position, and water depths are continuously plotted on a third printing device. For geological work on board POLARSTERN the Parasound system is the most important tool. Stations for taking geological samples from the seafloor can only be planned properly with information based on Parasound data. The echosounding data recovered during transit between stations are also very important for marine geological work. Therefore, the Parasound survey during ANT-XX/2 should cover the following goals and targets in addition to those relevant for the Riiser Larsen Sea: • Mapping sediment distribution patterns along transects across the Polar Frontal Zone (areas of non deposition and high accumulation), • To interpolate sediment budget and to identify transport processes of terrigenous and biogenic components to the seafloor during past climate periods, • To identify areas showing sedimentary sequences of high temporal resolution, • To provide information for the selection of locations for sediment coring (site surveys for future expeditions). Figure 2.11-3: Cruise track south of 60°S indicating distances with shutdown Hydrosweep and Parasound systems due to seals (S) or whales (W). The distance with measuring systems (black) was only 44% of total distance. In total 5400 nm of the cruise track were measured with the Parasound system. South of 60°S more then 50% of these targets could not been reached because of frequent shutdowns of the acoustic devices related to restrictive obligations by the German Environmental Agency (UBA) with respect to marine mammals protection. Furthermore, scientific interpretation of these data will be severely hampered by the frequent gaps in the data collection or will in many cases not be possible at all. Therefore, the collected profiles are of even less scientific value. With operating Parasound system a total of 58% of the transit tracks were measured (Figure 2.11-3). Because of difficulties during operation and avoiding damage of the towed hydroacoustic mammal monitoring streamer, the Parasound system was switched off on the southern part of the Prime Meridian profile and during very heavy sea ice conditions. Therefore, south of 60°S altogether on only 44% of the total travel distance sediment acoustic data could be collected. To minimize the acoustic emission the pulse length of the transmitted sound was selected to 2. This is equal to a very short pulse length of 0.5 ms at an operating frequency of 4 kHz. After shut down due to marine mammal observation the system was very slowly restarted 20 minutes after last sighting of a marine mammal. This procedure to slowly increase the emitted sound (Table 2.11-2) to scare away marine mammals took one hour and was conducted 98 times during ANT-XX/2 (equal to four days of potential profiling without any scientific data). This frequent on/off operation was very stressful for the system and ruined the inrush current limiter (which was bypassed later). Many problems with the online inkjet printers and errors (wrong position or time and date) in the record headers of the digitised data occurred throughout the whole cruise. This has destroyed data and will make data processing a time consuming work. Therefore, an upgrade of the Parasound system (DS3) is absolutely needed. A software controlled start-up procedure and a software control of sound transmission should be inserted to reduce ping rate and sound emission. Sites for sampling the seafloor were selected according to the Parasound data. All together 58 surface samples were collected with the Multicorer (MUC) or the Minicorer (MIC), the latter installed 20 m below the CTD (Table 2.11-1), a configuration that saved a couple of hours of station time. The water column at the hydrographic CTD stations was sampled for seawater stable isotope composition of dissolved inorganic carbon ∂13CDIC and ∂18O at 43 stations (Table 2.11-3). With the collected surface samples the sediment composition will be mapped and material for the development of micropaleontological transfer functions and trace element and stable isotope analyses of benthic forams and ostracodes is available. 2.11.3 PHYSICAL PROPERTIES OF THE SEDIMENT CORES Gerd Kuhn Sediment cores were taken with a gravity corer (SL) and a piston corer (KOL) on 18 stations during the cruise (Table 2.11-1). Physical properties like sediment density, p-wave velocity, and magnetic suscep-tibility were measured on the collected sediment cores with a GEOTEK multi-sensor core logger (MSCL). For calculation of these values core diameter and temperature were measured in addition (Table 2.11-4). For calibration the following parameter were used in the logger settings of the MSCL software (version 6) or afterwards: • Temperature calibrated with Hg-thermometer: T = 0.003754 x -23.518995 R2 = 0.99968 • Core thickness (displacement) with distance pieces D = 0.0019394 x 1.0001728 R2 = 0.99979 • p-wave travel time with a water core of known temperature and theoretical sound velocity. offset for gravity corer (SL) 7.79 µs and for piston corer (KOL) 8.15 µs (Table 2.11-4) • Gamma ray attenuation measurement and density calculation calculation with equation type y = -Ax2 + Bx + C The coefficients A, B, and C were determined with measurements on calibration cores with defined density steps (GEOTEK calibration software) for the gravity corer with y = 0.0001x2 - 0.0682x + 10.126, R2 = 0.9996, and for the piston corer y = 0.00002x2 - 0.0595x + 10.049, R2 = 0.9998 A and B, the linearity of the detector, were constant during the cruise. C, the sensitivity of the detector (IO drift), was variable (Figure 2.11-4) and determined with a constant attenuation measurement (PVC-core) before each sediment core measurement. The values are stored in the calibration files for each core and the variability of In(Io) for the gravity corers (Figure 2.11-5) and piston corers (Figure 2.11-6) reached maximum -7% deviation (PS63/149-3). • Magnetic susceptibility data were stored as sensor units and calculated for volume magnetic susceptibility (Table 2.11-4). Corrections for sensor drift during measurement and recalculation of core top and bottom data have been applied. Gravity corer sensor units times 6.391 Piston corer sensor units times 14.584 Figure 2.11-4: Stability of the gamma-ray detector: counts over 23 hours Figure 2.11-5: Stability of the IO-gamma attenuation measured during the cruise before measuring the gravity corer sediment cores. Figure 2.11-6: Stability of the IO-gamma attenuation measured during the cruise before measuring the piston corer sediment cores. All data were graphically controlled and bad values at core section boundaries were removed. The data will be stored in the database PANGAEA (www.pangaea.de). First results and comparison with studied sediment cores showed nicely recorded cycles in magnetic susceptibility variations in core PS63/149-3. Low values are characteristic for warm climate periods (Holocene, marine isotope stage 5) with high accumulation of biogenic silicate. During cold climate periods accumulation of terrigenous material was higher and increases magnetic susceptibility values (Figure 2.11-7). Figure 2.11-7: Volume corrected magnetic susceptibility values from sediment core PS63/149-3. 211.4 DYNAMICS OF A CHANNEL-LEVEE SYSTEM IN THE RIISER LARSEN SEA Christian Hass The goal of this part of the marine geological investigations includes the investigation of a broad system of channels and levees on the continental slope of the Riiser Larsen Sea. The major focus of the investigations is placed on mapping the working area in order to get an idea on the extent of this system. Channels form through dense water masses that flow down the continental slope. However, whether turbidity currents or colder and/or more saline waters than the ambient water masses form these dense waters are not known. Thus, the investigations aim at discovering the sources and reconstructing the principal processes that lead to channel formation in this area. A further goal is to investigate whether the channels are presently active pathways or whether they are old and/or pie-designed structures. Levees frame the majority of the channels. Results from an earlier investigation (ANT-XVII/2) suggest adequate sediment accumulation rates for high-resolution climate reconstructions. Levee formation is closely linked to the processes that form the adjacent channels. Thus investigations of the levees provide also information on channel activity and its links to climate development. Mapping was planned to be accomplished by Parasound sediment profiling the structure of the upper sediment layers and Hydrosweep swath sounding for bathymetry. Sediment samples were taken using a gravity corer (SL) and a multicorer (MUC). Parasound profiling The major goals and tasks of the Parasound surveys were: • to provide information on the general acoustic characteristics of the sediments (sediment types). These include penetration, and structure of the sediment; • to provide information on the horizontal extension of different sediment types and distinct reflectors in the sediment column; • to provide information in order to aid selecting core locations (site surveys); • to provide information on acoustic reflectors that shall be identified in sediment cores. • to contribute to a mapping of the sediment characteristics of channels and related levees in the Rilser Larsen Sea. • to classify sediment types that reveal information on sedimentation processes, • to discover areas with sediments of high temporal resolution, • to reconstruct and characterize pathways and processes of sediment-transport Within the working area (western Riiser Larsen Sea) a total track of 2169 nm was accomplished in order to carry out Parasound profiling and Hydrosweep mapping. However, due to the restrictive obligations for the usage of hydroacoustic systems by the Federal German Environmental Agency (UBA) in order to protect marine mammals only a patchy fraction of the track could be measured. Only 969 nm - equivalent to only 45% the total track - were recorded by Parasound and Hydrosweep respectively; 1200 nm (55%) were not recorded (Figure 2.11-8). The sonar systems were shut down very irregularly, sometimes within a channel, on top of a levee or even right before a channel-levee structure. Thus in-depth investigations of sedimentary processes and structural features of channels and levees that require information on entire channellevee systems were largely prevented. The information gained from this survey is of only very limited use since propagation of sedimentary features across channel-levee systems could not be measured in the majority of the cases. Gaps in the profile lines may hide second- or third-order channels that may be small but that can significantly affect sedimentary processes if situated on levee flanks. Figure 2.11-8: Cruise track in the Riiser Larsen Sea where channel/levee systems should be mapped and the acoustic systems were shut down at 55% (dark lines). Despite the incomplete survey data the following results can be extracted: Channel/levee systems form the most common relief structure in this part of the Riiser Larsen Sea. The channels reveal typical structures with very low sound penetration suggesting hard and/or coarse-grained sediments. The western sides of the channels are usually flanked by levees that show up to 200 m of acoustically well-stratified sediments. Within the levees sometimes smaller, second or third-order channels form; building up smaller levees that sit on the large channel levees. Wherever possible the map of the working area that was worked out based on ANT-XVII/2 data (Thiede & Oerter 2002) was updated. Sediment coring The planning was to carry out a precise Parasound survey and then select core locations on the basis of that survey. Since the survey data were not reliable in terms of continuity due to the above-mentioned restrictions all but two positions had to be selected based on data of an earlier expedition (ANT-XVII/2; Thiede & Oerter 2002). During the ANT-XVII/2 expedition a number of important locations had already been sampled, thus, additional sediment cores taken during ANT-XX/2 must be rated of only less importance. Long sediment cores (up to 13.8 m length) were taken using a gravity corer. The gravity corer includes a 2 t weight on the top and a variable number of steel pipes of 5 (3) m length each attached to the weight. Inside the steel pipes are plastic liners (12 cm Ø). Attached to the base of the gravity corer a core catcher is mounted that prevents the sediment core from sliding out of the plastic liners. Once recovered, the 5 (3 m) m plastic liners were cut into 1 m pieces. Subsequently the 1 m pieces were logged using a multisensor core logger. Undisturbed surface samples were recovered using a multicorer equipped with 12 tubes (6 cm Ø, 60 cm tube length). Multicorer lengths were usually around 30 cm. On every geological station within the working area gravity corer and multicorer were deployed. Due to time consuming marine-mammal-watches related to the Parasound and Hydrosweep profiling projects, opening of the sediment cores, core descriptions, sampling, X-radiography, colour scans, photographs, and further analyses could not be carried out on board. A total of 17 locations within the working area were sampled (Figure 2.11-9). Two locations were selected upon new Parasound data, 13 stations were selected on the basis of ANT-XVII/2 data, three stations were sampled upon occasion at a CTD station and during transit. Nine inner-channel locations were sampled. In every case the surface sediments consisted of very soft silty clay and could easily be cored using the multicorer. However, the gravity corer was not able to penetrate deeper than two meters. On five mid-channel locations the gravity corer was recovered empty suggesting that physically very hard sub-surface sediments prevented penetration. On one of these locations the damaged core catcher visibly released a small amount of sediment (i.e. all of the approx. 30-50 cm of sediment that made it up to the sea surface) when the corer came out of the water. Three of the mid-channel locations allowed to recover 147, 148, and 94 cm, respectively, of the sediment column (PS63/099-2, 105-2, 114-1). At two of these locations the coring gear was severely damaged. Cores PS63/099-2 and PS63/105-2 obviously got stuck in very dense and water depleted sediments that included larger stones (several cm Ø) in a yellowish silty-clayey matrix. These sediments significantly differed from all sediments cored in the Riiser Larsen Sea; it is presumably much older than the overlying softer sediments. Core PS63/114-1 went undamaged back on deck but revealed only 147 cm of sediment. The corer was obviously not able to penetrate a convolutedly bedded coarse-sand layer that occurred at the base of the recovered core. One of the cores (PS63/120-4) was taken on transit from the lower northern area of the western channel. It revealed 427 cm of soft sediments. Since the Parasound system had to be shut down no information on the position of this core location relative to the channel axis could be gained. Figure 2.11-9: Core recovery and length in the Riiser Larsen Sea in relation to location. References Thiede, U. & Oerter, H. (2002): The expedition ANTARKTIS XVII/2 of the Research Vessel POLARSTERN in 2000.- Rep. Polar Marine Res. 404, 1-245. Spiess, V. (1992): Digitale Sedirrentechographie- Neue Wege zu einer hochauflösenden Akustostratigraphie.- Ber. Fachber. Geowiss. Univ. Bremen, 35: 1-199. Table 2.11 -1: List of surface sediment samples and sediment cores from ANT-XX/2. Water Station Time depth Recov. Penetr. PS63/ Date (UTC) (m) LatidudeLongit.(S) GEAR (cm) (cm) Remarks Location ----- ---------- ----- ---- -------------------- ------ ----- ------ ----------------- -------------- 024-1 28.11.2002 16:06 4562 47°01.46' 04°52.85'E MIC 23 Cape Basin 025-1 29.11.2002 11:06 4086 49°00.12' 02°50.41'E MIC empty Cape Basin 026-2 29.11.2002 22:59 3918 50°15.00' 01°25.28'E MIC <3 SW-Ind. Ridge 027-2 30.11.2002 7:43 1342 51°00.20' 00°31.31'E MUC 10 SW-Ind. Ridge 028-2 01.12.2002 1:12 3011 52°01.18' 00°06.07'W MUC 35 SW-Ind. Ridge 030-3 01.12.2002 20:56 2581 52°59.55' 00°01.47'E MUC 13 SW-Ind. Ridge 032-2 03.12.2002 6.53 2764 54°00.36' 00°06.56'W MUC 30 SW-Ind. Ridge 033-5 03.12.2002 16:42 1632 54°31.24' 00°00.44'W MUC 20 SW-Ind. Ridge 035-2 04.02.2002 4:53 3427 55°29.45' 00°05.47'W MUC 20 SW-Ind. Ridge 037-4 05.12.2002 2:45 3334 55°55.62' 00°05.92'E MUC 24 SW-Ind. Ridge 033-2 05.12.2002 6:54 4352 56°31.33' 00°03.32'W MUC 33 SW-Ind. Ridge 039-2 05.12.2002 18:39 4018 57°31.38' 00°07.83'W MUC Not released SW-Ind. Ridge 039-3 05.12.2002 20.19 3989 57°31.64' 00°07.37'W MUC 32 SW-Ind. Ridge 041-2 06.12.2002 6:35 3839 58°28.89' 00°05.01'E MUC 33 SW-Ind. Ridge 042-4 07.12.2002 3:15 4667 59°02.70' 00°04.17'E MUC 41 SW-Ind. Ridge 043-2 07.12.2002 15:36 4580 59°27.92' 00°00.39'W MUC 36 SW-Ind. Ridge 047-2 08.12.2002 15:06 5423 60°58.36' 00°00.54'W MUC 37 N Weddell Sea 049-2 09.12 2002 6:51 5383 62°01.29' 00°03.61'W MUC 12 N Weddell Sea 052-2 09.12.2002 22:17 5310 63°00.13' 00°05.50'W MUC 10 N Weddell Sea 054-5 10.12.2002 23.14 5164 64°00.37' 00°01.15'E MUC 9 N Weddell Sea 057-2 16.12.2002 21:34 4220 68°30.67' 00°00.92'W MUC 35 N Weddell Sea 059-2 17.12.2002 10:25 4588 67°29.22' 00°00.48'E MUC 32 N Weddell Sea 061-3 18.12.2002 2:12 4500 66°30.42' 00°00.01'E MUC 26 N Weddell Sea 064-6 19.12.2002 17:43 3698 64°59.65' 00°02.70'E MIC 22 Maid Rise 068-1 25.12.2002 21:48 5427 61°00.27' 00°00.81'E KOL/25 1924 2100 TC=88cm N Weddell Sea 071-1 21.12.2002 12:31 5375 61°46.75' 02°04.50'E MIC 17 N Weddell Sea 073-1 22.12.2002 1:43 5345 62°33.16' 04°12.18'E MIC 12 Enderby Basin 076-2 22.12.2002 14:50 5330 63°17.63' 06°17.18'E MUC 37 Enderby Basin 078-1 23.12.2002 7:36 5190 64°06.85' 08°38.54'E MIC 24 Enderby Basin 080-1 23.12.2002 22:20 5213 64°33.70' 09°48.22'E MIC 24 Enderby Basin 081-3 24.12.2002 7:29 4804 64°53.34' 10°56.62'E MUC 36 Astrid Ridge 082-2 24.12.2002 15:18 4111 65°16.84' 12°11.85'E MUC 37 Astrid Ridge 083-2 25.12.2002 10:09 2612 65°40.29' 13°21.55'E MUC 16 Astrid Ridge 095-1 30.12.2002 12:00 1169 69°53.10' 25°14.00'E MIC 13 Riiser Larsen Sea 095-3 30.12.2002 17:12 1140 69°53.34' 25°12.75'E MUC 8 Riiser Larsen Sea 097-1 01.01.2003 8:46 3130 68°57.56' 17°34.37'E GKG failed Riiser Larsen Sea 097-2 01.01.2003 10:41 3046 68°57.85' 17°35.91'E MUC 37 Riiser Larsen Sea 097-3 01.01.2003 12:16 3068 68°57.71' 17°35.57'E SL/10m 872 1050 Riiser Larsen Sea 098-1 01.01.2003 14:30 2914 68°57.82' 17°41.55'E SL/l5m 1148 1300 Riiser Larsen Sea 098-2 01.01.2003 16:04 2868 68°58.32' 17°41.87'E MUC 36 Riiser Larsen Sea 099-1 01.01.2003 18:25 3625 68°59.25' 18°00.52'E MUC 36 Riiser Larsen Sea 099-2 01.01.2003 20:00 3627 68°59.26' 18°00.62'E SL/10m 94 100 damaged Riiser Larsen Sea 103-1 02.01.2003 12:48 3590 68°13.14' 16°44.67'E SL/15m 1080 1400 Riiser Larsen Sea 103-2 02.01.2003 14:24 3587 68°13.23' 16°44.32'E MUC 37 Riiser Larsen Sea 105-1 02.01.2003 23:59 4350 68°08.08' 18°12.37'E MUC 36 Riiser Larsen Sea 105-2 03.01.2003 1:45 4351 68°07.97' 18°12.78'E SL/15m 147 200 damaged Riiser Larsen Sea 106-1 03.01.2003 5:10 3754 68°06.26' 18°49.14'E SL/15m 1048 1200 Riiser Larsen Sea 106-2 03.01.2003 6:43 3749 68°06.20' 18°49.05'E MUC 37 Riiser Larsen Sea 109-1 03.01.2003 18:24 4494 67°24.04' 19°36.64'E MUC 36 Riiser Larsen Sea 109-2 03.01.2003 20.10 4489 67°25.06' 19°36.73'E SL/5m cc-sample 0 failed Riiser Larsen Sea 110-1 04.01.2003 0:23 4230 67°25.06' 20°40.82'E SL/15m 991 1550 Riiser Larsen Sea 110-2 04.01.2003 2:11 4235 67°25.06' 20°49.14'E MUC 30 Riiser Larsen Sea 111-1 04.01.2003 5:52 4517 67°25.69' 21°31.33'E MUC 35 Riiser Larsen Sea 111-2 04.01.2003 7:39 4509 67°25.69' 21°31.40'E SL/3m 0 0 failed Riiser Larsen Sea 112-1 04.01.2003 1:36 4480 67°04.97' 21°06.29'E SL/15m 1380 1550 Riiser Larsen Sea 112-4 04.01.2003 13:57 4482 67°04.92' 21°06.22'E MUC 38 Riiser Larsen Sea 113-1 04.01.2003 19:26 4459 66°28.52' 21°30.61'E MUC 35 Riiser Larsen Sea 113-2 04.01.2003 21:16 4457 66°28.50' 21°30.76'E SL/15m 1068 1500 Riiser Larsen Sea 114-1 05.01.2003 0:40 4706 66°35.71' 22°05.32'E SL/3m 148 200 Riiser Larsen Sea 114-2 05.01.2003 2:33 4697 66°35.71' 22°05.03'E MUC 37 Riiser Larsen Sea 115-1 05.01.2003 5:17 4744 66°37.71' 22°15.64'E MUC 21 Riiser Larsen Sea 115-2 05.01.2003 7:06 4735 66°37.69' 22°13.30'E SL/3m 0 0 failed Riiser Larsen Sea 117-1 06.01.2003 2:00 4737 66°27.02' 17°10.76'E MUC 36 Riiser Larsen Sea 117-2 06.01.2003 3:52 4733 66°27.06' 17°10.79'E SL/3m 0 100 failed Riiser Larsen Sea 116-1 06.01.2003 8:37 4347 66°24.17' 15°48.27'E SL/15m 235 500 damaged Riiser Larsen Sea 118-2 06.01.2003 10:21 4355 66°24.15' 15°48.34'E MUC 12 Riiser Larsen Sea 120-3 07.01.2003 3:16 4890 66°24.46' 18°29.43'E MUC 40 Riiser Larsen Sea 120-4 07.01.2003 5:18 4890 65°24.34' 18°29.04'E SL/5m 427 550 Riiser Larsen Sea 121-2 07.01.2003 11:25 4977 64°57.43' 19°01.22'E MIC 25 Riiser Larsen Sea 123-3 08.01.2003 10:11 5017 64°08.10' 20°45.44'E MUC 39 Riiser Larsen Sea 123-4 08.01.2003 12:12 5010 64°08.16' 20°45.30'E SL/8m 0 0 failed Riiser Larsen Sea 126-2 09.01.2003 7:59 5089 62°59.56' 22°58.88'E SL/5m 0 0 failed Enderby Basin 126-3 09.01.2003 9:55 5108 62°59.66' 22°58.01'E MUC 40 Enderby Basin 130-2 10.01.2003 5:18 5181 61°29.97' 23°00.05'E MUC 37 Enderby Basin 130-3 10.01.2003 7:20 5131 61°29.84' 22°59.76'E SL/10m 1136 1200 Enderby Basin 132-1 10.01.2003 17:10 5210 60°53.61' 22°59.98'E KOL/25 aborted Enderby Basin 135-2 11.01.2003 12:31 4825 59°29.97' 23°00.53'E MUC empty Enderby Basin 136-1 11.01.2003 17:06 5375 59°19.26' 22°59.54'E KOL/25 1640 1700 Damaged TC=85cm Enderby Basin 136-2 11.01.2003 20:13 5388 59°19.43' 22°59.56'E MUC 29 Enderby Basin 139-1 12.01.2003 11:55 5370 58°18.84' 22°59.76'E KOL/20 empty released EnderbyBasin 139-2 12.01.2033 14:35 5368 58°17.97' 23°00.05'E MUC 33 Enderby Basin 139-3 12.01.2003 17:36 5379 58°17.79' 22°59.86'E KOL/20 empty Released at 5200m Enderby Basin 141-2 13.01.2003 7:12 5412 57°30.91' 22°59.06'E MUC 26 Enderby Basin 143-2 13.01.2003 20:14 4810 56°30.43' 23°00.85'E MUC 35 Enderby Basin 146-1 14.01.2003 10:36 4733 55°19.24' 23°00.01'E MUC 32 Enderby Basin 146-2 14.01.2003 13:16 4730 55°19.26' 23°00.03'E KOL/20 1782 2100 TC=43cm Enderby Basin 149-2 15.01.2003 6:08 3804 53°57.25' 23°02.86'E MUC 31 SW-Ind. Ridge 149-3 15.01.2003 8:43 3805 53°57.32' 23°02.87'E KOL/25 2119 2400 TC=65cm SW-Ind. Ridge Table 2.11-2: Softstart parameter settings of the Parasound system. Minutes Channel Pulse startup Select Gain Mode Angle Length ------- ------- ---- ---- ----- ------ 0 NBS 1 1 20 1 10 NBS 10 1 20 1 20 NBS 100 1 20 1 30 PAR/NBS 100 1 20 1 40 PAR/NBS 100 4 20 1 50 PAR/NBS 100 4 4 1 60 PAR/NBS 100 4 4 2 Table 2.11-3: List of CTD/rosette water sampler, sampled for seawater stable isotope composition. waterdepth, Station Gear Lat. S Long. Pmax or. HS ---------- ---- --------- ---------- ----------- PS63/024-1 CTD 47°01.46' 04°52.85'E 4625 0°-Transect PS63/032-1 CTD 54°00.13' 00°06.42'W 2683 PS63/033-4 CTD 54°31.47' 00°00.24'W 1565 PS63/037-3 CTD 56°56.46' 00°04.96'E 3720 PS63/041-3 CTD 58°28.68' 00°05.77'E 3832 PS63/043-1 CTD 59°28.65' 00°01.74'W 4628 PS63/047-1 CTD 60°59.26' 00°02.86'W 5460 PS63/052-1 CTD 63°00.08' 00°04.87'W 5370 PS63/057-1 CTD 68°30.36' 00°00.77'W 4300 PS63/061-4 CTD 66°30.59' 00°00.04'E 4570 PS63/076-3 CTD 63°17.64' 06°17.18'E 5330 NW-SE-Transect PS63/081-2 CTD 64°53.15' 10°57.54'E 4913 PS63/082-1 CTD 65°16.90' 12°09.57'E 4145 PS63/083-1 CTD 65°40.14' 13°21.22'E 2660 PS63/087-1 CTD 66°27.51' 17°38.36'E 4870 GeoBox South PS63/090-1 CTD 67°59.48' 20°15.17'E 4052 PS63/093-1 CTD 69°15.16' 24°08.95'E 3267 PS63/095-1 CTD 69°53.10' 25°14.00'E 1176 PS63/100-1 CTD 69°13.53' 17°57.86'E 2508 PS63/101-1 CTD 68°49.38' 17°59.27'E 3700 PS63/104-1 CTD 68°14.46' 17°59.82'E 4314 PS63/107-2 CTD 67°39.63' 17°59.92'E 4566 PS63/116-1 CTD 66°48.06' 16°59.51'E 4707 PS63/120-2 CTD 65°24.42' 18°29.45'E 4985 GeoBox North PS63/124-1 CTD 63°44.70' 21°44.10'E 5145 PS63/125-1 CTD 63°30.07' 22°59.56'E 5166 23°E-Transect PS63/126-1 CTD 62°59.78' 22°59.27'E 5196 PS63/127-1 CTD 62°29.93' 23°00.06'E 5222 PS63/131-1 CTD 60°59.90' 22°59.92'E 5272 PS63/133-1 CTD 60°30.00' 23°01.18'E 5163 PS63/134-1 CTD 59°57.66' 22°59.65'E 5034 PS63/135-1 CTD 59°29.94' 23°00.76'E 4900 PS63/140-1 CTD 58°00.93' 22°59.56'E 5303 PS63/141-1 CTD 57°30.35' 22°59.78'E 5250 PS63/142-1 CTD 57°00.58' 22°59.65'E 4717 PS63/143-1 CTD 56°30.25' 23°00.40'E 4880 PS63/144-1 CTD 56°00.23' 22°59.90'E 3736 PS63/145-1 CTD 55°30.37' 23°00.91'E 4358 PS63/147-1 CTD 55°00.59' 23°00.40'E 4534 PS63/148-1 CTD 54°30.18' 22°59.85'E 3567 PS63/149-1 CTD 53°57.01' 23°02.99'E 3857 PS63/150-1 CTD 53°29.42' 23°00.20'E 3123 PS63/152-1 CTD 52°59.90' 22°59.54'E 1942 Table 2.11-4: Sensors and parameter settings for measurements with the GEOTEK multi-sensor core logger. P-Wellengeschwindigkeit und Kerndurchmesser Platten-Transducer-Durchmesser: 4 cm Transmitter Pulsfrequenz: 500 kHz Pulswiederholungsrate: 1 kHz registrierte Pulsauflösung: 50 ns gate: 2800 delay: 10 Ls P-Wellenlaufzeit offset: 7.79 Ls (SL, 2*2.5 mm Wandstarke), 8.15 Ls (KOL, 2*2.7 mm Wandstärke) Temperature = 20°C, Salinity = 35 psu, not corrected for water depth and in situ temperature. Temperatur Bimetall Sensor Density Gammastrahlenquelle: Cs-137 Aktivität: 356 MBq Energie: 0.662 MeV Blendendurchmesser: 5.0 mm (SL+KOL) Gammastrahlendetektor: Gammasearch2, Modell SD302D, Ser. Nr. 3047 , John Caunt Scientific Ltd., 10 s Zählzeit Fractional porosity Mineral grain density = 2.75, water density 1.026 Magnetische Susceptibilität Spulensensor: BARTINGTON MS-2C, Ser. Nr. 208 (SL+KOL) nominaler Spuleninnendurchmesser: 14 cm Spulendurchmesser: 14.8 cm Wechselfeldfrequenz: 565 Hz, Zählzeit 10 s, Präzision 0.1 * 10-5 (SI) Magnetische Feldstärke: ca. 80 A/m RMS Krel: 1.56 (SL, 12 cm Kern-ø), 0.69 (KOL, 8.46 cm Kern-ø) Spulensensorkorrekturfaktor 6.391 (SL) 14.584 (KOL) für 10-6 (SI) Dickenmessung Penny + Giles, Type HLP 190..., Ser.#.Nr. 92730147 2.115 SYNPART SYNOPTICAL INVESTIGATION OF THE PARTICLE FLUX IN THE EASTERN WEDDELL GYRE Walter Geibert, Claudia Hanfland and Regina Usbeck The starting hypothesis for this study was that in the Eastern Weddell Gyre between 0°E and 35°E, a hitherto overlooked region of high productivity, would be found. This assumption was supported by model results derived from nutrient budgets (Usbeck 1999, Usbeck et al. 2002), data of whale abundance (Tynan 1998) as well as by other data from adjacent areas. Satellite data of surface chlorophyll do not show a pronounced anomaly at that region, and a further question was whether such a high productivity region could be overlooked by the satellites due to deep chlorophyll. However, hydrographical and geochemical data from the region of interest itself were extremely sparse. Therefore, a study was initiated which should allow to get an impression of the particle flux. Real-time SEAWIFS-satellite images of the region would allow comparing on-site measurements with remote sensing data. Chlorophyll profiles were measured in order to compare deep and surface chlorophyll, as well as to get a general idea of phytoplankton activity in the region. Oxygen was measured onboard on all CTD profiles, and nutrient samples were taken for later analysis in the home laboratory. 234Th was measured on depth profiles in order to get estimates of export productivity. Surface sediment samples were taken in order to determine accumulation rates when back in the home lab. Thus, an impression of particle flux throughout the whole water column could be obtained. Satellite images The SEAWIFS chlorophyll data for the region show a larger bloom for the eastern part of the Weddell Gyre than in previous years. So far, the results agree with chlorophyll measurements. However, the absolute chlorophyll concentrations given by SEAWIFS for the bloom in the eastern Weddell Gyre do not at all reflect the absolute values obtained by in-situ chlorophyll measurements Whereas satellite data give surface values of 2 µg/l in the eastern Weddell Gyre, yet uncalibrated in-situ fluorometer values are substantially higher (5-15 µg/l), and only part of this discrepancy can be explained by the deep chlorophyll maxima. As there had been very few chlorophyll profiles from the Southern Hemisphere available for calibration of the SEAWIFS data, it seems reasonable to assume that remote sensing data are substantially underestimating the productivity of the Weddell Gyre. However, the calibration of the fluorometer has to be awaited before final conclusions are drawn. Chlorophyll A seapoint fluorometer was deployed with all CTD stations (Figure 2.11-10), except a few in the beginning of the cruise. Additionally, about 150 samples were taken from the CTD bottles for later analysis of pigment concentration, which will allow to calibrate the fluorometer measurements of chlorophyll-a (Chl-a). Three transects of chlorophyll-a were obtained, one N-S at 0°E from about 52°S to the Antarctic coastline (Figure 2.11-11a), one with NW-SE orientation from about 0°E, 64°S to 23°E, 70°S (Figure 2.11-11b) and a further S-N transect, mostly at 23°E (Figure 2.11-11c), covering the core of the region of interest. The three sections shown below (Figure 2.11-11a-c) illustrate that the Weddell Gyre is in general much more productive than could be derived from satellite images. Whereas the blooms in the ACC reach about 2 µg/l Chl-a (all values uncalibrated) and are relatively homogeneous with depth, the profiles in the Weddell Gyre are typically much lower at the sea surface but reach Chl-a concentrations up to 15 µg/l. In the eastern Weddell Gyre, extremely high values of Chl-a were found, sometimes exceeding the fluorometer's range (up to 15 µg/l). Maxima were typically between 7 and 15 µg/l in the eastern Weddell Gyre from about 62.5 to 55°S. These values fully support the starting hypothesis, revealing a huge area of high productivity just where predicted by model results. For final results, the calibration of the fluorometer has to be awaited. Figure 2.11-10: Locations of all CTD-depth profiles including fluorometric determination of chlorophyll a. Figure 2.11-11: Concentration of chlorophyll a (fluorometrically, yet uncalibrated) vs. depth. a: N-S transect along 0°E, b: NW-SE-transect, c: N-S transect along 23°E (see Figure 2.11-9 for details). Thorium-234 234Th (half-life 24.1 days) is a naturally occurring radionuclide that originates from the 238U decay chain. It is very particle reactive, and with increasing particle concentration an increasing part of 234Th is found on particles. Recent observations sugest that acid polysaccharides, a product of phytoplankton, are the main adsorber for 234Th in natural seawater (Quigley et al. 2002) Generally spoken, the fraction of 234Th found on particles may be considered a measure for biogenic particle concentration under open ocean conditions. When particles sink out of the euphotic zone, they carry 234Th with them. Consequently, particle export leads to an export of 234Th, too. As the activity of 234Th is in equilibrium with 238U when no export takes place, the disequilibrium between 238U and 234Th is a measure for particle export (Coale & Bruland 1985). In order to get information on carbon export, 25 vertical profiles of 234Th from the upper water column were measured (Figure 2.11-12) as described in Usbeck et al. (2002). Preliminary results show a good agreement with the chlorophyll data. High fractions of Th on particles are found in regions with high chlorophyll concentrations. On the eastern transect, a strong depletion of Th was found that can be explained by particle export. The subsurface maximum of chlorophyll is often reflected in particulate 234Th. Figure 2.11-12: Locations of the 234Th depth profiles Oxygen Samples for oxygen analysis were the first to be drawn from the Niskin bottle unless chlorofluorocarbon (CFC) samples were taken. Volume calibrated glass bottles of ∼120 mL were used. A piece of Tygon tube was attached to the outlet tap of the Niskin bottle to allow the water to enter the sample bottle with minimum air contact and turbulence. The sample was allowed to overflow up to three times the bottle volume and the temperature of the seawater was then measured. The oxygen was chemically fixed and the bottles were capped and shaken. Samples were analyzed using the standard Winkler method [Grasshoff and Ehrhardt, 1983] within 12 h of collection. Whole bottle titrations were performed as recommended for WOCE [Culberson, 1994]. The titration process was automated and the endpoint calculated using an electronic burette and photometer linked to a computer (SiS GmbH Dissolved Oxygen Analyzer). Duplicate samples were drawn and analyzed for 10% of all the samples. The analytical precision of these duplicates was 0.45%. Nutrients Polyethylene (PE) 50 mL bottles were used to collect subsamples from Niskin bottles for nutrient analysis. The PE bottles were rinsed three times with the sample water. The samples were poisoned with 105 mg/mL mercuric chloride (HgCl2), stored at 4°C and analyzed at the home laboratory 7 months after sampling. This preservation method has been shown to be successful for the storage of nutrient samples for up to 2 years [Kattner, 1999]. A Technicon autoanalyser II was used to measure the concentrations of Si, NOx−, NO2− and NH4+ using standard techniques [Grasshoff and Ehrhardt, 1983]. All the samples were analyzed in duplicate and the average difference of the duplicates from the mean was 0.23% for NO3− and 0.26% for Si. Temperature and salinity Temperature and salinity were recorded with a Seabird SEACAT SBE 19 instrument. Here, we report 5 m averages. Bottle data were related to the salinity and temperature of the nearest 5 m data point. A comparison of the physical data with that from another CTD instrument, which was operated in parallel and continuously calibrated against seawater standards (M. Schröder et al., The structure of the eastern Weddell Sea warm inflow, manuscript in preparation, 2010) yielded excellent agreement. Surface sediment samples From selected samples of the sediment surface, 230Th activities will be determined in the near future in order to obtain sediment accumulation rates that may be compared with production data from the overlying water column. For locations of the sediment samples, see the respective chapters in this cruise report. Preliminary conclusions The obtained dataset gives for the first time a comprehensive insight into the production patterns of the eastern Weddell Gyre. The preliminary results fully support the starting hypothesis of a hitherto overlooked high productivity region in the Southern Ocean. REFERENCES Coale K.H. & Bruland K.W. (1985): 234Th:238U disequilibria within the California Current.- Limnol. Oceanogr. 30: 22-33. Quigley M.S., Santschi P.H., Hung C.-C., Guo L. & Honeyman B. (2002): Importance of acid polysaccharides for 234Th complexation to marine organic matter.- Limnol. Oceanogr. 47: 367-377. Tynan, C.T. (1998): Ecological importance of the southern Boundary of the Antarctic circumpolar current.- Nature 392: 708-710. Usbeck, R. (1999): Modeling of marine biogeochemical cycles with an emphasis on vertical particle fluxes.- Rep. Polar Marine Res. 332, http://www.awi- bremerhaven.de/GEO/Publ/PhDs/RUsbeck Usbeck, R., Rutgers van der Loeff, M.M., Hoppema, M. & Schlitzer, P. (2002): Shallow remineralization in the Weddell Gyre.- Geochem. Geophys. Geosyst. 3: 10.1029/2001GC000182. 2.12 VIRIOPLANKTON ABUNDANCE AND BACTERIOPHAGE OF OLIGOTROPHIC BACTERIA FROM POLAR SEAS Jifang Yang and Timo Hagemann Viruses are now considered to be an important component of aquatic microbial communities. The re-evaluation of the role of viruses in marine ecosystem is due to the discovery of high numbers of viruses and their abundances, typically numbering ten billions per litre. They probably infect all organisms, undergo rapid decay and replenishment and influence many biogeochemical and ecological processes, including nutrient cycling, respiration system, particle-size distributions and sinking rates, bacterial and algal biodiversity and species distributions, algal bloom control, dimethyl sulphide formation and genetic transfer. The marine bacterial community is responsible for a considerable portion of primary production and regeneration of nutrients in the microbial loop and is associated with a great variety of marine bacteriophages. The phages are parts of the marine virioplankton community and are capable of infecting a large portion of the bacterioplankton. It is assumed that, as part of the marine food web, bacteriophages play important quantitative and qualitative roles in controlling marine bacterial populations. Oligotrophic bacteria have been defined as organisms with the capability to grow on a medium containing 1 mg or less than 1 mg of organic carbon per liter and have been found as the dominant populations in the Pacific Ocean and the polar seas. Occurrence and distribution of oligotrophic bacteria in Antarctic and Arctic seas were investigated and a few hundred of oligotrophic strains were isolated. Although there are a lot of reports about bacteriophages of marine heterotrophic bacteria, no reports of bacteriophages infecting marine oligotrophic bacteria are available. Investigating virioplankton abundance and bacteriophages of oligotrophic bacteria in polar seas are very important for better understanding the interactions between phages and their host organisms and the role of viruses in the polar marine ecosystem. As part of an international cooperation between the AWI and SIO (Second Institute of Oceanography, China) this research cruise served to sample sea water and concentrate virus solution on board. Work at sea At ten stations in the Weddell Sea, seawater samples of about 200 liters were taken with a CTD-Rosette. The normal sample depths were 25 m and at two stations we took an additional sample of 400 m water depth. After separating algae and bacteria cells with a 0.2 µm / 0.45 µm Sartobran Capsule, the bacteriophages and viruses were concentrated thousandfold by tangential-flow-ultrafiltration using three Polyethersulfone Ultrasart Cassettes (0.1 m2 effective filtration area each; 100 kdalton cut off). Twelve host bacteria strains, belonging to the alpha or gamma subclass of proteobacteria or the Cytophaga-Flavobaoterium-Bacteroides group, were infected each with 0.1 ml of the concentrated virus solution and incubated at 8°C to determine the bacteriophage concentration in seawater by counting the number of plaques on the plates. Meanwhile, about three litres seawater sample in every sampling station were filtered through a glasfibre filter for POC/PON measurement. This POC/PON measurement will be done in home laboratory. Preliminary results At each station a 200 ml bottle was filled with sample of the concentrated virus solution (Table 2.12-1). The twelve bottles were collected and stored at 4°C for further studies in home laboratory (morphology observation and DNA sequence analysis of virus). Preliminary results from plaque assay test confirmed the existence of oligobacteriophages in Antarctic Sea (Figure 2.12-1). There were high emergence rates relatively of phage plaque against host strain ARK126 (25%) or ANT43 (37%). Table 2.12-1: Sampling stations Sample Total No Station No Depth plaques ------ ---------- ----- ------- 1 PS63/038-1 25 m 28 2 PS63/042-5 400 m 0 3 PS63/042-7 25 m 3 4 PS63/047-3 25 m 7 5 PS63/054-3 25 m 2 6 PS63/061-2 25 m 4 7 PS63/076-1 25 m 4 8 PS63/081-1 25 m 3 9 PS63/081-4 400 m 3 10 PS63/107-1 25 m 7 11 PS63/120-1 25 m 3 12 PS63/123-1 25 m 3 Figure 2.12-1: Total number of occurred plaques No phage plaque against host strain ARK150 or ARK152 or ARM58 or ARK176 occurred ACKNOWLEDGEMENTS Especially, we want to thank technical assistant Mrs. Susanne Spahic who was involved deeply in preparations for the cruise expedition. This international cooperation project between the Alfred Wegener Institute and the Second Institute of Oceanography, 99 PR China, (CHN 01/034) was supported by the German Federal Ministry of Education and Research (BMBF). Addendum of ANT-XIX/4 2.13 COMMUNITY STRUCTURE AND ABUNDANCE OF OLIGOTROPHIC BACTERIA T.-L. Tan, S. Spahic', C. Germer Objectives Although not integrated in the ANDEEP projects, the aim of our participation is to study the abundance and diversity of oligotrophic, low-nutrient bacteria in south polar seas by using conventional and molecular biological methods. The results will be compared with the results of a similar expedition programme to the north polar region from June to August 2002 (ARK XVIII / la+b). Work on board For the above purpose, we have taken water samples at 10 stations from four depths (25, 100, 200, and 400 m). The water sampler (Rosette) was combined with CTD measurements (conductivity-temperature- salinity) in the water column (Table 2.13-1). Table 2.13-1: Salinity (psu) and temperature (°c) at the bacteriological stations Internal no. PS no. Date Sal.Min. Sal.Max. Temp.Miri. Temp.Max. ------------ -------- ---------- -------- -------- ---------- --------- Bac St 01 61/130-2 03.03.2002 33.842 34.689 -0.18 2.547 Bac St 02 61/131-5 05.03.2002 33.374 34.675 -1.734 0.668 Bac St 03 61/133-2 07.03.2002 34.062 34.674 -1.713 0.601 Bac St 04 61/134-2 08.03.2002 32.845 34.684 -1.554 0.545 Bac St 05 61/135-2 10.03.2002 34.044 34.679 -1.544 0.531 Bac St 06 61/136-2 12.03.2002 34.11 35.662 -1.322 0.963 Bac St 07 61/137-2 14.03.2002 34.004 34.674 -1.218 0.773 Bac St 08 61/138-1 16.03.2002 33.223 35.617 -1.283 0.508 Bac St 09 61/139-2 19.03.2002 33.8812 34.6908 -0.6876 1.932 Bac St 10 61/141-1 22.03.2002 33.8823 34.6711 -1.1257 1.0599 The seawater samples have to be filtered for fluorescence in situ hybridizations (FISH) of the bacteria cells with phylogenetic specific oligonucleotide probes. Unfortunately, the stainless steel 10-fold filtration apparatus for FISH did not work smoothly for getting the amounts of filters needed, because the teflon sealing in the apparatus was damaged. Therefore, we could not get enough bacterial biomass to inspect ten different phylogenetic groups, as planned before. Enrichment cultures in dialysis chambers and in Erlenmeyer-flasks with screw-on caps were kept at 4°C for further attempts to enumerate and isolate oligotrophic bacteria in the home laboratory. Bacterial biomass for clone libraries from 25 and 400 m water depths has to be collected from 50 litres of seawater by means of a tangential flow microfiltration apparatus. However, the tangential flow filtration device did not function satisfactorily, because the desired high speed for the seawater flow of 4 litres per minute with the peristaltic pump was not reached with the Marprene tube delivered by the manufacturer. Silicone tubing was needed to get the high speed necessary for cell concentrations. Bacterial biomass was therefore concentrated on Millipore GP50 filters. Seawater samples were also prepared in glass ampoules for dissolved organic carbon (DOC) and particulate organic carbon / particulate organic nitrogen (POC / PON) determinations on glass-fibre filters. All preparations of seawater samples were kept frozen at -30°C. Note We got surface sediment samples to determine bacterial biomass from the stations 139-4, 139-8, 140-3, 142-4 and 142-5. The results will be of interest for the meiofauna working groups. 3 ANNEX The achievements during the cruise were to a large extent due to the effective and friendly cooperation between the ship's crew and the participating scientific personal. 3.1 BETEILIGTE INSTITUTE/ PARTICIPATING INSTITUTES ANT-XX/1-2 Acronym Adresse Teilnehmerzahl ------- ------------------------------ -------------- Deutschland AWI Alfred-Wegener-Institut 38 für Polar- und Meeresforschung Columbusstraße 27558 Bremerhaven BFN Bundesamt für Naturschutz 1 INA - Insel Vilm 18581 Putbus BIA Berufsgenossenschaftliches 1 Institut für Arbeitssicherheit Mirecourtstr. 9 53225 Bonn DWD Deutscher Wetterdienst 6 Geschäftsfeld Seeschifffahrt Jenfelder Allee 70 A 22043 Hamburg DSMZ Deutsche Sammlung von 1 Mikroorganismen und Zellkulturen GmbH Mascheroder Weg 1b 38124 Braunschweig FIELAX FIELAX 3 Gesellschaft für wissenschaftliche Datenverarbeitung mbH Schifferstraße 10-14, 27558 Bremerhaven GL Germanischer Lloyd AG 3 Vorsetzen 32/35 20459 Hamburg GKSS GKSS Forschungszentrum 2 Institut für Küstenforschung Max-Planck-Straße 21502 Geesthacht HSW Helicopter Service 4 Wasserthal GmbH Flughafen Hamburg Geschäftsfliegerzentrum, Geb. 347 22335 Hamburg IMPG Institut für Mineralogie 1 Petrologie und Geochemie der Universität München Theresienstraße 41/III 80333 München ISITEC ISITEC GmbH 1 Stresemannstr. 46 27570 Bremerhaven IUPB Universität Bremen 5 Institut für Umweltphysik Otto-Hahn-Allee 1 28359 Bremen IUPH Universität Heidelberg 3 Institut für Umweltphysik Im Neuenheimer Feld 229 69120 Heidelberg LAEISZ Reederei F. Laeisz 1 Barkhausen-Str. 37 27568 Bremerhaven OPTIMARE Optimare Sensorsysteme AG 1 Coloradostraße 5 27580 Bremerhaven See-BG Seeberufsgenossenschaft 1 Reimerstwiete 2 20457 Hamburg WERUM Werum Software & Systems AG 1 Wulf-Werum-Str. 3 21337 Lüneburg China SOA Second Institute of Oceanography 1 PO Box 1207 Hangzhou P. R. China Frankreich GENAVIR GENAVIR Zone portuaire de Bregallion B.P. 330 83507 La Seyne-sur-mer cedex IFREMER IFREMER 2 Centre do Toulon Zone portuaire de Bregallion B. P. 330 83507 La Seyne-sur-mer cedex OCEANO OCEANO Technologies 1 Rue Rivoalon, Sainte-Anne du Portzic 29200 Brest Großbritannien CER Centre of Environmental Risk 1 University of East Anglia Norwich NR4 7TJ CHYORK University of York 2 Dept. of Chemistry York, YOlO 5DD lENS Lancaster University 1 Environmental Science Lancaster, LA1 4YQ UMIST University of Manchester 1 Institute of Science and Technology PO Box 88 Manchester M6O 1QD Norwegen LIT Universitetet i Tromsø 1 Institutt for Geologi Dramsveien 201 9037 Tromsø Südafrika UTC University of Cape Town 4 Dept. of Oceanography Rondebosch 7701 Cape Town 3.2 WISSENSCHAFTLICHES PERSONAL / SCIENTIFIC CREW Name Institut ANT-XX/1 ANT-XX/2 ------------------------------ ----------- -------- -------- Ansorge Isabelle Jane UTC X Baier Uli FIELAX X Bakker Dorothee CER X Belier Frederic OCEANO X Bluszcz Thaddus AWI X Boebel Olaf AWI X Brückner Sylvia AWI X Büchner Jürgen HSW X Buldt Klaus DWD X Caba Armando GKSS X Deckelmann Holger AWI X Didié Claudia AWI X Dinter Wolfgang BFN X Durham Louise ENS X El Naggar Saad AWI X Forwick Matthias UIT X Fütterer Dieter Karl AWI X Geibert Walter AWI X Gerchow Peter FIELAX X Giljam Rhys Thomas UTC X Graeser Jürgen AWI X X Graeve Martin AWI X Hagemann Timo AWI X Halasia Magdalini A. UPH X Hanfland Claudia AWI X Hass Christian AWI X Heckmann Hans-Hilmar HSW X Hemmerling Börge UPH X Hoppema Jan Marinus UEB X Jaeneke Matthias DWD X Kattner Gerhard AWI X Klatt Olaf AWI X Kleffel Guido AWI X Knuth Edmund DWD X Krischat Joachim AWI X Kuhn Gerhard AWI X Lakaschus Sönke GKSS X Lehnberg Barbara DSMZ X Lensch Norbert AWI X Max Thomas AWI X Menßen Jens HSW X Mizdalski Elke AWI X Monsees Matthias AWI X Müller Eugen DWD X Niederjasper Frederic AWI X Niehoff Barbara AWI X NN AWI X NN GL X NN GL X NN GL X NN IFREMER X NN IFREMER X Nunez Ismael AWI X Pols Hans-Arnold DWD X Reinke Manfred AWI X Rohardt Gerd AWI X Rohr Harald OPTIMARE X Sablotny Burkhard AWI X Sander Hendrik IUPB X Schattenhofer Martha IUPB X Schiel Sigrid AWI X Schmidt Thomas FIELAX X Schmitt Wolfgang IMPG X Schröder Michael AWI X Schulz Astrid AWI X Seidler Kai HSW X Thomalla Sandy UTC X Usbeck Regina FIELAX X Vöge Ingrid AWI X Wagner Eberhard LAEISZ X Wahl Sebastian AWI X Waldthausen, v. Constanze AWI X Webb Adrian Myles UTC X Wevill David CHYORK X X Williams Paul Ivor UMIST X Wittling Thomas AWI X Yang Jifang SOA X 3.3 SCHIFFSPERSONAL / SHIP'S CREW Rank Name ANT-XX/1 ANT-XX/2 ---------- ---------------- ----------- -------- -------- Master Domke Udo X X 1.Offc. Spielke Stefan X 1 Offc. Schwarze Stefan X Ch. Eng Pluder Andreas X X 2 Offc. Spielke Stefan X 2. Offc. Szepanski Nico X X 2. Offc. Thieme Wolfgang X X R. Offc. Koch Georg X X Doctor Böttcher Herbert X 1. Eng. Delif Wolfgang X X 2. Eng. Ziemann Olaf X X 3. Eng. Zornow Martin X X Electr. Muhle Heiko X X Boatsw. Clasen Burkhard X X Carpenter Reise Lutz X X AB Gil glesias Luis X X AB Pousada Martinez S. X X AB Kreis Reinhard X X AB Schulz Ottmar X X AB Burzan G.-Ekkehard X X AB Moser Siegfried X X AB NN X X AB Hartwig Andreas X X Storek Preußner Jörg X X Mot-man Ipsen Michael X X Mot-man Voy Bernd X X Mot-man Elsner Klaus X X Mot-man Hartmann Ernst-Uwe X X Mot-man Grafe Jens X X Cook Haubold Wolfgang X X Cookmate Völske Thomas X X Cookmate Silinski Frank X X 1. Stwdess Jürgens Monika X X Stwdss/KS Wöckener Martina X X 2. Stwdess Czyborra Bärbel X X 2. Stwdess Silinski Carmen X X 2. Steward Gaude Hans-Jürgen X X 2. Steward Möller Wolfgang X X 2. Steward Huang Wu-Mei X X Laundrym. Yu Kwok Yuen X X CCHDO DATA PROCESSING NOTES Date Person Date Type Event Summary ---------- ----------------- --------- ------------------------------------------------------ 2004-02-17 Witte, Hannelore CTD/SUM Submitted 1999a, 2000a, 2002a Data Submitted Together This is information regarding line: A12 ExpoCode: 06ANTXVI_2, ANTXVIII_3, ANTXX_2 Cruise Date: 1999/01/18 - 2003/01/15 From: WITTE, HANNELORE Email address: hwitte@awi-bremerhaven.de Institution: AWI Country: GERMANY The file: AWICTD.tar - 4248576 bytes has been saved as: 20040217.052429_WITTE_A12_AWICTD.tar in the directory: 20040217.052429_WITTE_A12 The data disposition is: • Public The file format is: • WHP Exchange The archive type is: • Other: Tar/Zip/Tar The data type(s) is: • Summary (navigation) CTD File(s) The file contains these water sample identifiers: • Cast Number (CASTNO) • Station Number (STATNO) WITTE, HANNELORE would like the following action(s) taken on the data: • Merge Data 2004-04-13 Bartolacci, Danie SUM Website Update Notes on sumfile reformatting: 2004.04.13 DMB I have reformatted the A12_2002a sumfile: • Changed expocode from 06ANTXX_2 to 06AQ200211_2 • Changed date format from yyyymmdd to mmddyy • Added event code as UN • Changed position format from DD.dd to DD MM.mm • Added hemisphere alphabetic • Added NAV as UNK • Realigned all columns to conform with WOCE standards • Added name/date stamp • Ran sumchk with no errors file was renamed a12_2002asu.txt and put online. 2004-04-15 Bartolacci, Danie CTD/SUM To go online EXCHANGE Format, No Qual Values CTD files are in .csv format, but at present have no quality bytes associated with values and therefore cannot be converted to netCDF at this time. A directory and web page files have been created for this cruise. All station track and data files link. This cruise will not link to the website until web-generating code is working and run. Notes on sumfile reformatting: 2004.04.13 DMB I have reformatted the A12_2002a sumfile: • Changed expocode from 06ANTXX_2 to 06AQ200211_2 • Changed date format from yyyymmdd to mmddyy • Added event code as UN • Changed position format from DD.dd to DD MM.mm • Added hemisphere alphabetic • Added NAV as UNK • Realigned all columns to conform with WOCE standards • Added name/date stamp • Ran sumchk with no errors file was renamed a12_2002asu.txt and put online. Date Person Date Type Event Summary 2004-04-20 Bartolacci, Danie CTD Website Update • Added quality bytes for all values (2 if valid value was present, -999. if value was missing) and associated comment lines in header. • Added CTDOXY and flag column with missing values and missing value flag. This was done in order to convert files into netcdf (our in-house code requires all columns be present). • Renamed all station files to CCHDO format. • Converted files to netcdf with no apparent errors.