CONTINUOUS PCO(2) MEASUREMENTS IN SURFACE-WATER OF THE NORTHEASTERN TROPICAL ATLANTIC

The partial pressure of CO2 in the area of the northeastern tropical Atlantic influenced by the Mauritanian upwelling is highly variable in time and space. Partial pressures between 300 and 450 mu atm were observed in autumn 1991 and spring 1992. In the oceanic region off the Mauritanian coast, the range of spatial variations in pCO(2) was low (between 365 and 395 mu atm, in autumn, and between 332 and 353 mu atm in spring). In this area, the seasonal pCO(2) variations were mainly due to temperature effects. Even in the upwelling region, where the biomass was high, there was not a single relationship valid for the whole area between chlorophyll fluorescence and pCO(2). On the other hand, pCO(2) at a constant temperature was, on an average, decreasing with temperature. A comparison with older data shows that pCO(2) in the surface seawater of the open ocean has evolved as the atmospheric pCO(2) the last twenty years.