Distribution of surface water partial CO2 pressure in the English Channel and in the Southern Bight of the North Sea

The concentrations of dissolved CO2 dissolved oxygen and chlorophyll have been determined in the surface seawater of the English Channel and of the Southern Bight of the North Sea in June 1992, April–May 1993 and September–October 1993. The partial pressure of CO2(PCO2) displays large spatial and temporal variations ranging from 100 ppm up to 670 ppm. The relationship between seawater pCO2 and chlorophyll distribution is discussed and compared with data recently obtained in the North Atlantic by A. J. Watson, C. Robinson, J. E. Robertson, P. J. le B. Williams and J. R. Fasham (1991)Nature, 350, 50–53. Air-sea CO2 fluxes have been calculated from wind speed and pCO2 data and, due to the combined effect of both of those parameters, the flux can be as high as about 150 mmol m−2 d−1. This implies that shelves could play an appreciable role in the global C budget. Further extended C02 level measurements should be made to improve flux estimations for the coastal zone on a global basis.