THE CARBON-DIOXIDE SYSTEM IN THE ATLANTIC-OCEAN

During the National Oceanic and Atmospheric Administration's Ocean Atm osphere Carbon Exchange Study expedition in the eastern North Atlantic in summer 1993, measurements of four CO2 parameters, along with hydro graphic properties, were made: fugacity of CO2, fCO(2) (measured at 20 degrees C and in situ); pH (measured at 20 degrees C); total inorgani c carbon, TCO2; and total alkalinity, TA. The major objective of this cruise was to establish a benchmark against which future measurements of the transient invasion of CO2 can be made. The large-scale distribu tions of surface water CO2 parameters were related to temperature and salinity in this region. The subsurface TA and TCO, measurements were fitted to multiple linear functions of salinity, in situ temperature, apparent oxygen utilization, and silicate. The measurements of the ino rganic carbon system were also used to examine the internal consistenc y of the carbonate system in this area. The measurements were internal ly consistent to +/- 1,3 % in fCO(2), +/- 0.006 in pH, +/- 3 mu mol kg (-1) in TCO2, and +/- 3 mu mol kg(-1) in TA if proper carbonic acid di ssociation constants are used for different input combinations. The th ermodynamic constants of Goyet and Poisson [1989], Roy et al. [1993], Millero [1995], and Lee and Millero [1995] were most consistent with t he measurements of pH (at 20 degrees C), TCO2, and TA. However, if fCO (2) (at 20 degrees C) is used in thermodynamic calculations, the const ants of Mehrbach et al. [1973] gave the best representation of measure ments. The constants of Lee and Millero [1995] were also reasonable ag reement with these measurements.