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

CRUISE REPORT 
Repeat hydrography on Line PR6
A.	 Cruise narrative
A.1.	 Highlights
a.	 WOCE designation: 	PR6
b.	 Expedition designation: 	18DD9505/1
c.	 Chief scientist: 	Frank Whitney
Institute of Ocean Sciences
P.O. Box 6000
9860 West Saanich Road
Sidney, B. C. V8L 4B2
Telephone: 604-363-6816
Telefax: 604-363-6476
Internet: whitney@ios.bc.ca
d.	 Ship: 	John P. Tully
e.	 Ports of call: 	Patricia Bay, B.C.;  Ucluelet, B.C.
f.	 Cruise dates: 	May 8 to May 26, 1995
A.2.	 Cruise Summary Information
a.	 Geographic boundaries: 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). 

b.	 Stations occupied: The stations occupied on the cruise are 
tabulated by type in Table 1.

Table 1.

No. of Stations


shallow rosette/CTD
15
200 m casts on return leg

deep rosette/CTD
6
4000 m maximum depth

CTD only
21
3000 m maximum depth

Uncontaminated Sea Water
29
4 m deep intake

Moorings
5
sediment traps, 5 sites

c.	 Floats and drifters deployed:  A drifting sediment trap line was 
deployed and recovered after 3 days at Station PRS1. At PRS1 an in situ 
drifter was deployed for half the daylight period to measure 
primary production rates.

d.       Moorings deployed or recovered:  Sequential sediment traps,
each holding 21 sample cups were deployed for one year at stations
 P4, P12, P16, P20 and P26. Traps were recovered from P4 and P26 after
 one year in the ocean.

A.3.	 List of Principal Investigators

Principal Investigator 	Parameters	Institution
Howard Freeland	Ocean circulation 	IOS
C. S. Wong	Carbonate chemistry	IOS
Frank Whitney	Coordinator	IOS
Philip Boyd	Plankton ecology, JGOFS	UBC

A.4.	 Scientific Programme and Methods
A CTD survey along Line PR6 was completed except for 2 stations near PRS1.  
Salinity, oxygen, CFCs and nutrients (NO3 + NO2, PO4 and Si) were analyzed 
onboard ship from rosette casts at 6 stations. 
JGOFS participants sampled water at several stations for phytoplankton studies.  
Incubated samples from P12 and PRS1 were enriched with iron and
incubated under natural light to further test the importance of Fe on
phytoplankton growth.  Preliminary Results: Slightly lower nutrient
levels than in February and a marked increase in the amount of material
in the final cup of our sediment trap indicate that spring growth had
recently begun at PRS1.  Sea water pCO2 was consistently below
atmospheric levels along Line PR6, much more so nearer the coast.
Surface waters characterized by a mixed layer depth of less than 50 m,
salinity of less than 32.4 and no nitrate extended about 200 km
offshore.  Goals Achieved:  repeat hydrography line completed except
for 2 CTD stations near PRS1.  Sediment traps recovered and deployed at
several stations.  Onboard chemistries all were successful.  JGOFS
studies were completed as planned.

A.5.     Major Problems and Goals Not Achieved 
A winch failure restricted our water sampling at PRS1 to 3000 m.  
A.6.	Other Incidents of Note
A.7.	List of Cruise Participants
Participant
Institute
Participant
Institute

Frank Whitney
IOS
Philip Boyd
UBC

Tim Soutar
IOS
John Berges
Brookhaven

John Love 
IOS
Hugh Maclean
UBC

Reg Bigham
IOS
Sarah Thornton
volunteer

Wendy Richardson
IOS
Kate Read
volunteer






B.	 Underway Measurements
B.1.	 Navigation and bathymetry 
A SAIL (Standard ASCII Interface Loop) system onboard ship poles several 
sensors at 2 min intervals.  Data is stored on a micro computer and is 
subsequently processed in a format that is accessible for general use.  
ShipÕs speed, heading and position are logged.
B.2.	 Acoustic Doppler Current Profiler (ADCP) 
A hull mounted current profiler logged upper layer currents every 5 min 
throughout the cruise
B.3.     Thermosalinograph and underway dissolved gasses Temperature
and conductivity sensors are installed near the intake of a sea water
line that is used as a scientific supply in the laboratory.  Data is
logged on SAIL.  Sea and air pCO2 concentrations were measured hourly
throughout the cruise.


B.4.	 Expendable bathythermograph and salinity measurements 
None.
B.5.	 Meteorological observations 
Logged on SAIL are wind speed, atmospheric pressure and air temperature.

B.6.	 Atmospheric chemistry 
None.
C.	 Hydrographic Measurements
C.1.	 CTD profiles
For most stations, when rosette sampling was not required, a Guildline
8705 CTD was used to measure T, S and P to a maximum depth of 3000 m.
A rosette mounted Guildline 8737 measured T, S, P and transmissivity at
6 stations along Line PR6.  At station PRS1, profiles with each CTD
were taken for comparison.
C.2.	 Water sampling
Two rosette holding 23 or 11-10 L polycarbonate bottles were used for
all hydrographic sampling. Go-Flo bottles clamped on Kevlar hydro line
were used to collect clean water for plankton studies and iron
measurements.  At each station outbound on Line PR6, samples for
chlorophyll, salinity and nutrients were collected from the ship's sea
water loop (Uncontaminated Sea Water or USW) which pumps water from
about 4 m continuously into the laboratory.  Duplicate Niskin bottles
were tripped on 12 occasions, and analyses performed on both.  The
standard deviation for pairs from this sample set is calculated by sp
=  {Sd2/2k}0.5 where k is the number of pairs and d is the difference
between pairs.


T
C
S
O2
uM/kg
Si
uM/kg
NO3&NO2
uM/kg
PO4
uM/kg
F11
pM/kg
F12
pM/kg

sp
0.0047
0.0011
0.61
0.2
0.28
0.007
0.076
0.049

k
12
12
12
12
12
12
8
8


C.3.	 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.
C.4.	 Oxygen 
Samples were preserved and titrated according to the method of Carpenter (1965).  
A Brinkman Dosimat and Colorimeter were used to automate the titration.  
Standards were prepared as outlined in WOCE Report 73/91. 
C.5.	 Nutrients
Samples from hydrographic casts were collected in polystyrene tubes, and 
refrigerated for a maximum of 20 hours before being analyzed. Loop samples 
(USW) were stored up to 2 days at 4oC before being analyzed.   NO3+NO2, PO4 and 
Si were  measured 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 prepared freshly the week before the cruise
started from oven-dried (80oC) 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).
C.6.	 TCO2, 13C and Alkalinity
A single profile was collected at PRS1 for all 3 parameters. Samples were fixed 
with HgCl2 and refrigerated.
C.7.	 JGOFS sampling
Go-Flo bottles were used to collect water for POC/N, DOC/N,
chlorophyll, nano- and microplankton and incubation experiments.
Sedimentation rates were measured over a 3 day period using a series of
9 drifting sediment traps to 1000 m.  Moored sediment traps measure the
yearly flux of particles to deep ocean.  Iron enrliched samples were
incubated in natural light for up to 8 days to continue work on the
importance of Fe in controlling phytoplankton growth in the N.E.
Pacific.
D.	 Acknowledgements
This program is funded by Department of Fisheries and Oceans (DFO), National 
Science and Engineering Research Council (NSERC) and Panel for Energy Research 
and Development (PERD), Canada.  The cooperation and enthusiasm of the crew of 
John P Tully add greatly to the success and enjoyment of this work.
E.	 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.
