THE INTERNAL CONSISTENCY OF CO2 MEASUREMENTS IN THE EQUATORIAL PACIFIC

During a recent NOAA JGOFS Equatorial Pacific cruise all four analytic al parameters of the carbonate system were measured-pH, total alkalini ty (TA), total carbon dioxide (TCO2), and the fugacity of carbon dioxi de (fCO(2)). The measurements made during leg 2 on surface waters have been used to examine the internal consistency of the carbon dioxide s ystem in these waters. The internal consistency of the measurements wa s examined by using various inputs of the measured parameters (pH-TA, pH-TCO2, pH-fCO(2), fCO(2)-TA, fCO(2)-TCO2 and TA-TCO2) to calculate t he components of the CO2 system. The results indicate that the measure ments have an internal consistency of +/-0.003-0.006 in pH, +/-5-7 mu mol kg(-1) in TA, +/-5-7 mu mol kg(-1) in TCO2 and +/-6-9 mu Atm in fC O(2) if reliable constants are used for the dissociation of carbonic a cid in seawater. These results indicate that our present understanding of the thermodynamics of the carbonate system in seawater is close to the present accuracy in measuring the various parameters of the syste m (+/-0.002 in pH, +/-4 mu mol kg(-1) in TA, +/-2 mu mol kg(-1) in TCO 2 and +/-2 mu Atm in fCO(2)).