Distribution and air-water exchange of carbon dioxide in the Scheldt plume off the Belgian coast

In the present paper we report partial pressureof CO2 (pCO2) data obtained off theBelgian coast during 24 cruises. The temporaland spatial resolution of this data set allowsus to discuss satisfactorily seasonal andinter-annual variability of pCO2 in thestudy area. The dynamics of pCO2 aredescribed using two approaches: fixed referencestations and area survey cruises. The air-waterfluxes of CO2 in the Scheldt estuarineplume and in the outer-plume region areestimated quantitatively, showing that theseareas correspond respectively to a net annualsource and sink of atmospheric CO2. Theannually integrated air-water fluxes for theScheldt estuarine plume range between +1.1 and+1.9 mol m−2 year−1 as a function ofthe formulation of the exchange coefficient ofCO2. The annual net emission of CO2from the estuarine plume to the atmosphere isestimated to be between +2.3 to +4.0 Gmolyear−1 which represents 17 to 29% of theestimate reported in the literature for the Scheldtinner estuary.