DIURNAL-VARIATION IN SURFACE PCO2 AND O2 AT 60-DEGREES-N, 20-DEGREES-W IN THE NORTH-ATLANTIC

A method for rapid determination of the partial pressure of carbon dioxide at the sea-surface is described. The method was employed along with a pulsed oxygen electrode to monitor daily changes in surface pCO2 and O2 close to a drifting buoy deployed at approximately 59-degrees-N, 20-degrees-W. During a 4 day period a gradual rise in oxygen saturation and corresponding fall in pCO2 was observed in the surface layer. Corrections are made for gas exchange of O2 using wind speed data, the correction being an important fraction of the supersaturation observed in the water. Estimates of net community production and photosynthetic quotients are derived, giving a range of PQs from 0.9 to 1.5. Though variations in the local hydrography reduce the accuracy of these estimates, the potential of this approach to estimate productivity appears promising.