US JGOFS Antarctic Environments Southern Ocean Process Study (AESOPS)

Revelle Leg KIWI09, APFZ Process 2, 13 Feb.-19 Mar., 1998

Documentation for: THE TRACE METAL ROSETTE HYDROGRAPHIC BOTTLE DATA 

L.A. Codispoti (lou@ccpo.odu.edu)
Old Dominion University,  April, 1999

General Comments:

This "readme" file pertains to the salinity, dissolved oxygen,
and nutrient data taken from sampling bottles with the trace
metal rosette that was equipped with 8 ~30-liter teflon coated
"Go-Flo"  bottles made mostly of PVC and equipped with orange
silicone o-rings during Revelle leg RR09 (13 February - 13 March
1998).  This rosette system was equipped with a Sea-Bird  SBE-19
CTD.  Dr. Wilford Gardner of the Department of Oceanography at
Texas A & M University (wgardner@ocean.tamu.edu) was the chief
scientist during this leg.  This cruise was the second process
leg on the R/V Roger Revelle during the U.S. JGOFS program in the
Southern Ocean (AESOPS).  The Revelle legs focused on the Polar
Front region and complemented several AESOPS cruises on board the
R/V Nathaniel Palmer that focused on the Ross Sea.  Many casts
with a hydrographic rosette equipped with 24, 10-l Bullister
bottles and a higher resolution CTD system were also taken during
this leg. These hydrographic data are of "WOCE" quality and have
been submitted as a separate file because of the different
capabilities of the two CTD/rosette systems.   The user should
also be aware that underway hydrographic data were also collected
during this leg and that these data are not included in this
report.  

Some questionable data are not included in this report. These
data are available upon request.  

No units are given for salinity in this report because the most
recent definitions of salinity define it as a dimensionless
number.  To accommodate every preference, Winkler oxygen values
are reported in ml/l, micromolar and micromoles per kg.  The
latter values can only be calculated with a knowledge of the
oxygen sample temperatures when the samples were drawn.  These
"draw temperatures" are not reported here, but can be obtained by
contacting lou@ccpo.odu.edu.  Nutrient values are reported in
micromolar.  The nutrient values in micromolar can be converted 
to micromoles per kg, by combining a temperature of 21 deg. C and
the salinity of the sample to compute density and then dividing
the value in micromolar by this number.

Methods:

In general, the methods employed for the bottle salinity, Winkler
dissolved oxygen, and nutrient analyses did not differ
significantly from those described in the JGOFS protocols that
were distributed in 1994 (UNESCO, IOC Manual and Guide #29).
Minor differences included the following:  1) The protocols give
one a choice of adjusting nutrient methods so that calibration
curves are strictly linear, or opting for more response and
taking into account non-linearities.  We chose the latter method. 
2) No corrections were made for "carryover" between nutrient
samples run on the Technicon Autoanalyzer.  Carryover effects in
our nutrient analyses are generally less than ~2% of the
concentration difference between adjacent samples, and were
minimized by arranging samples in depth order and by running some
samples twice.  3) Calibration and re-calibration of volumetric
ware were not exactly as described in the JGOFS protocols, but
all volumetric flasks, maxipettors, and dosimats were 
calibrated.  4) Duplicate oxygen samples were not routinely
drawn.  5) The JGOFS protocols do not describe an automated
technique for the analysis of ammonium concentrations.  We
employed the Berthelot reaction  using a method somewhat similar
to the method described by Whitledge et al. (1981, Whitledge,
T.E., Malloy, S.C., Patton, C.J. and Wirick, C.D. Automated
Nutrient Analyses in Seawater. Brookhaven National Laboratory
Rept.  BNL 51398, 216pp.). 

Temperature:

The temperature data associated with each bottle depth were taken
by the CTD system during the bottle tripping process.  Consult
the companion CTD data report for this cruise to learn more about
the CTD system.     

Sampling:

The samples in this report were taken from ~30 liter Go-Flo
bottles.  Because there is little or no lag time between
triggering a bottle and bottle  closure with the new Sea-Bird
rosette systems, our sampling protocols request that bottles be
held at the sampling depth for at least 30 seconds before
tripping.

NOTE THAT THE MID-POINTS OF THE SAMPLING BOTTLES WERE ~ O.5 METER
ABOVE THE CTD SENSORS.  THE DATA HAVE NOT BEEN CORRECTED FOR THIS
OFFSET.  

Salinity:

Salinities were determined with Guildline Autosal salinometers. 
New vials of  standard sea-water were used to standardize before
and at the end of every run.  Agreement between bottle salinities
and the  sensors  on the Sea-Bird SBE-19 CTD  was usually better
than 0.015.  Some larger differences occurred in gradients
because of the response time characteristics of the sensors in
this system which did not produce high quality data in gradients
during the cruise. See the companion CTD report for additional
information. 

Dissolved oxygen:

The Winkler dissolved oxygen apparatus was built under the
direction of Bob Williams (bob@odf.ucsd.edu) and supplied by the
Scripps Institution of Oceanography's (SIO) Ocean Data Facility
(ODF) group.  This system is computer controlled and detects the
end-point photometrically.  Temperatures of the thiosulfate and
standard solutions are automatically monitored by this system.  

Nutrients:

Note that the terminology used to describe nutrients has become
somewhat loose over the years and that silicate = silicic acid,
dissolved silicon or reactive silicate, and phosphate = reactive
phosphorus.  Nutrient analyses were performed on a 5-channel
Technicon II AA system that was modified and provided by Doug
Masten (doug@odf.ucsd.edu) of the ODF group at the Scripps
Institution of Oceanography.  

Queries:

Questions about these data may be addressed to:

Dr. L. A. Codispoti
CCPO
Old Dominion University
Norfolk, VA 23529
lou@ccpo.odu.edu