This database
presents measurements of total carbon dioxide
(TCO2), total alkalinity
(TALK), and
radiocarbon (
14C), as
well as hydrographic
and chemical data,
taken during the
Research Vessel
Thomas Washington
Expedition TUNES-1
in the Equatorial
Pacific Ocean (Section
P17C) as part of the World Ocean
Circulation Experiment (WOCE). The cruise
began in San Diego,
California, on May 31,
1991, and ended in
Papeete, Tahiti, on
July 11, 1991. WOCE
Meridional Section
P17C, along 135°W
and between ~5°S and
36°N, was completed during the 42-day
expedition. All 123 hydrographic stations
(including nine large-volume stations) were
completed to the full water column depth.
Spacing between stations was 30 nautical miles,
except between 3°N and 3°S, where it was 10
nautical miles. At 30 stations, CO2
measurements were provided for the
U.S. Department of Energy's carbon dioxide
research. Hydrographic and chemical
measurements made along WOCE Section P17C
included pressure, temperature, salinity and
oxygen (measured by conductivity, temperature,
and depth sensor), as well as bottle
measurements of salinity, oxygen, phosphate,
nitrate, nitrite, silicate, chlorofluorocarbons
CFC-11 and CFC-12, carbon-14, Total Carbondioxide (TCO2), and
total alkalinty (TALK). In addition,
potential temperatures
were calculated from
the measured
variables.
The TCO2
concentration in 1022
seawater samples was
determined by
semiautomated
coulometry using an
improved version of
the instrument. The
precision of these
measurements was
estimated to be better
than ±0.01%. The
desired accuracy was better than 4 
mol/kg.
The TALK concentration in 323 seawater samples was determined by an automated potentiometric acid titration system. The precision of the measurements was estimated to be better than 0.1%.
Fifty replicate samples were also collected for later shore-based reference analyses of TCO2 and TALK by vacuum extraction and manometry in the laboratory of C. D. Keeling of Scripps Institution of Oceanography.
