Ships of opportunity have been used to investigate ocean–atmosphere CO2 fluxes in the English Channel and Southern Bight of the North Sea. Continuous underway measurements of the fugacity of seawater carbon dioxide ( fCO2 sw), chlorophyll, temperature and salinity have been performed along 26 transects during the spring and autumn periods. The spatial fCO2 sw distribution along the Channel and Southern Bight is modulated by the photosynthetic activity, temperature changes and water mixing between inputs from the North Atlantic Ocean and riverine discharges. The seasonal variability of fCO2 sw is assessed and discussed in terms of the biology and temperature effects, these having similar impacts. The variation of fCO2 sw shows similar interannual patterns, with lower values in spring. The annual average of air–sea CO2 fluxes places the English Channel as neutral area of CO2 uptake. The spring and autumn data allow differentiating between distal and proximal continental areas. The Southern Bight shows a tendency towards net CO2 uptake on the distal continental shelf, whereas the Scheldt and Thames Plumes show a CO2 source behaviour on the proximal continental shelves.

This work was developed and funded within the ECO project (MCyT REN2002-00503/MAR) and from European Commission (EU FP6 CARBOOCEAN Integrated Project, Contract No. 511176-2). “Diputation de Pontevedra” financed X.A. Padin with a predoctoral grant.

12 páginas, 5 figuras, 3 tablas

Peer reviewed