WHP Line No.: PR6
Last Updated: Jaunuary 28, 1997

CRUISE REPORT: Repeat Hydrography on Line PR6:
WOCE Cruise No. 18DD9609/1

Chief Scientist: Philip Boyd
Ship: John P. Tully
Ports of Call:  none
Cruise Dates: May 6 to May 30, 1996
Expedition Designation: 18DD9609/1

Cruise Narrative
Our repeat hydrography section continues to be a joint program with Canadian JGOFS.

A CTD survey along Line PR6 was completed.  Salinity, oxygen and
nutrients (NO3 & NO2, PO4 and Si) were analyzed onboard ship from
rosette casts to 400 m and B-20 (bottom depth minus 20 m) at 5 stations
(MP 04, MP12,  MP 16, MP 20, and PRS1). DMS was analyzed in sea water
at the same stations to a depth of 400 m. and at three different time
periods at station PRS1.  DOC/N was sampled in sea water at the same
stations to 600 m and several deeper samples at station PRS1.  The DON
samples were analyzed onboard.
  
Free drifting sediment traps were deployed at MP04 to 300 m and PRS1 to
1000 m. and recovered two and six days later respectively.  Sequential
sediment traps were recovered and redeployed at stations MP04, MP12,
MP16, MP20 and PRS1.

 A transition zone survey was carried out north to south of line P from
 P11 to P09.  Ten stations were sampled to 200 m by rosette and
transmissometer.  Samples were collected to 100 m for salinity,
chlorophyll and nutrients.

JGOFS participants collected samples for biomass estimates at 5
stations, and incubated water to measure growth and grazing rates of
various groups of plankton.  A large volume in situ pumping system (J.
Bishop) was successfully deployed at 6 stations.

Cruise Summary Information
Cruise track
Line PR6 starts at the mouth of Juan de Fuca Strait on the west coast
of Canada, and heads almost due west for 900 n mi.  The terminal
station is PRS1, formerly designated Ocean Weather Station Papa (50 N,
145 W).

Table of Stations by type

Sample type:
No. stations:
Max. depth (m):

CTD casts
28
3000 db

Rosette/Hydro casts
14
4250

Loop samples
31
5

Surface drifter
1
1000 m

Moorings
1
4300 m




Floats, Moorings and Drifters deployed
A mooring with an optical package and S4 current meter, both in the
mixed layer, was recovered and redeployed.  A surface drifter that
collects temperature and barometric pressure data was deployed at
station PRS1 for AES.  Sequential sediment traps were recovered and
redeployed at 5 stations.  A free drifting string of sediment traps was
deployed at P04 and P26.

Principal Investigators  
Howard Freeland
Ocean circulation 
IOS

C.S. Wong
Climate chemistry
IOS

Frank Whitney
WOCE coordinator
IOS

Philip Boyd
JGOFS coordinator
UBC


Goals Achieved
CTD survey of Line PR6. 
Successful Rosette casts at 5 stations on Line P.
Completion of JGOFS sampling for plankton and productivity measurements.
Six large volume pump stations on Line P for particulates.
Recovery of sediment trap samples from 6 traps.

Problems and Goals not Achieved
None.

Cruise Participants & Affiliations

Tim Soutar
Mooring coordinator
IOS

John Love
Watch coordinator
IOS

Bernard Minkley
Oxygens, watch
IOS

Ron Bellegay
Moorings, pC02, watch
IOS

Wendy Richardson
DMS, DOC/N
IOS

Janet Barwell-Clarke
Nutrients, WOCE files
IOS

Ken Morgan
Bird, mammal Observer, Watch
IOS

Philip Boyd
Phytoplankton
UBC

Robert Goldblatt
Zooplankton biomass
UBC

Hugh Maclean
Watch, plankton sampling
UBC

Nelson Sherry
Bacteria
UBC

Maureen Soon
particulate 13C & 15N
UBC

Delphine Thibault
Zooplankton excretion
Rimouski U.

Ken Crocker
Mesozooplankton grazing
Memorial U.

Paul Matthews
Bacterial production 
Memorial U.

Jennifer Putland
Micro-zooplankton
Memorial U.

Jim Bishop
pump sampling
U. Victoria

Todd Mudge
pump sampling
U. Victoria

Robert Schultz
pump sampling
U. Victoria

IOS = Institute of Ocean Sciences, Sidney, B.C., Canada.
UBC = University of British Columbia, Vancouver, B.C., Canada


Measurement Techniques and Calibrations

CTD profiles
	At all stations, a Guildline 8715 CTD (S.N. 58483) coupled with
	a transmissometer was lowered to a maximum of 3000 m.

Water sampling
	A rosette holding a Guildline WOCE CTD (S.N. 59607) and 23-10 L
	polycarbonate Niskin bottles was used for most water sampling.
Go-Flo bottles clamped on Kevlar hydro line were used to collect clean
water for plankton studies.

	At each station, samples for surface chlorophyll, salinity and
	nutrients, and O18 were collected from the ship's sea water
loop which pumps water from about 5 m continuously into the
laboratory.
 
Salinity
	Samples were collected in glass bottles and analyzed onboard
	ship using a Guildline Model 8410 Portasal.  The Portasal was
standardized daily with IAPSO standard sea water Batch P128.

Oxygen 
	An automated titration system (Brinkman Dosimat and Fiber Optic
	Probe Colorimeter) using the micro-Winkler method (Carpenter,
1965), titrated samples to the iodine end-point.  Standards were
prepared as outlined in WOCE Report 73/91.
  

Nutrients
	Samples from hydro casts were collected in polystyrene tubes
	and refrigerated for a maximum of 12 h before being analyzed.
Loop samples (USW) were stored up to 2 days at 4oC before being
analyzed.  NO3+NO2, PO4 and Si were analyzed using a Technicon
Autoanalyzer.
	NO3+NO2 samples were reduced with Cd/Cu, then complexed with
	sulfanilamide and N-Naphthylethylene-diamine to form an azo dye
(Technicon Method No. 158-71W/B).  PO4 produces a molybdenum blue
complex in presence of acidic molybdate and ascorbic acid (Technicon
Method No. 155-71W).  Dissolved Si also forms a molybdenum blue complex
and oxalic acid removes PO4 interference (Technicon Method 186-72W).
	Concentrated standards were freshly prepared the week before
	the cruise from oven dried reagents.  Working standards were
made every 1 to 2 days by diluting 1 to 6 mL of various stock solutions
to 250 mL with 3.2% NaCl (w/v in double run Milli-Q water).  Standards
were checked against Acculute Standards (Anachemia Science) with good
agreement (peak heights agreed to within 1%).
	Silicate samples 105 to 95 ( 1000 to 3600 m) from Station MP16
	are flagged Quality 3.  The standards run as samples on this
day were low. The high standard should have been 135 uM and was
actually 129.2 uM and the extra high standard should have been 180 uM
and was actually 175 uM.  Nitrate and phosphate standards were not
affected, indicating a problem with the silicate channel only.

Table.  Laboratory temperatures for nutrients and salinity.
date
temp (C)
date
temp (C)

May 9
24.1 - 26.1
May 13
24.0 - 21.0 

May 16
22.5 - 23.8
May 19
23.5 

May 20
22.7 - 22.3
May  21
22.4 - 23.5

May 24
21.3 - 23.7
May 26
23.1 - 24.1

May 27
27.2 - 27.5
May 28
27.8 - 28.1



TCO2, 13C,  and Alkalinity,  were collected at MP04, MP12, MP16, MP20
and PRS1.  Samples were fixed with HgCl2 and refrigerated.

O18/O16 - samples were collected in 60 mL polyethylene bottles at stations MP04, MP12, MP16, 
MP20, and PRS1 and refrigerated.

JGOFS sampling -  Go-flo bottles were used to collect water for POC/N,
DOC/N, chlorophyll, nano- and micro-plankton and incubation
experiments.  At PRS1, an in situ drifter was deployed for 7 h to
measure primary production rates.  Deck incubations were conducted to
measure growth rates of bacteria, phytoplankton and micro-zooplankton.



References

Carpenter, J.H.  1965. The Chesapeake Bay Institute technique for the Winkler dissolved oxygen 
method.  Limnol. Oceanogr., 10: 141-143.

Technicon Industrial Method No. 155-71W.  1973.  Orthophosphate in water and seawater. 

Technicon Industrial Method No. 158-71W/A.  1977.  Nitrate and nitrite in water and seawater. 

Technicon Industrial Method No. 186-72W/B.  1977.  Silicates in water and seawater.

WOCE Report 73/91.  1991.  A comparison of methods for the determination of dissolved 
oxygen in seawater.

