Variability of the gas transfer velocity of CO2 in a macrotidal estuary (The Scheldt)

We report a large set of 295 interfacial carbon dioxide (CO2) flux measurements obtained in the Scheldt estuary in November 2002 and April 2003, using the floating chamber method. From concomitant measurements of the air-water CO2 gradient, we computed the gas transfer velocity of CO2. The gas transfer velocity is well correlated to wind speed and a simple linear regression function gives the most consistent fit to the data. Based on water current measurements, we estimated the contribution of water current induced turbulence to the gas transfer velocity, using the conceptual relationship of O’Connor and Dobbins (1958). This allowed us to construct an empirical relationship to compute the gas transfer velocity of CO2 that accounts for the contribution of wind and water current. Based on this relationship, the spatial and temporal variability of the gas transfer velocity in the Scheldt estuary was investigated.Water currents contribute significantly to the gas transfer velocity, but the spatial and temporal variability (from daily to seasonal scales) is mainly related to wind speed variability.Bioges

Role of pelagic calcification and export of carbonate production in climate change « PEACE » (SD/CS/03) - Final Report

The overall objective of the PEACE project is to evaluate the role in climate regulation of calcification, primary production and export processes during coccolithophorid blooms. We use a transdisciplinary approach that combines process-oriented field investigations with laboratory experiments and modelling tools. Specific objectives are: 1) to study the net ecosystem dynamics during coccolithophorid blooms, 2) to unravel the link between the bacterial community, grazing, transparent exopolymer particles (TEP) dynamics, carbon export and dimethylsulfide (DMS) cycling during coccolithophorid blooms, 3) to assess the effects of ocean acidification on coccolithophorid metabolism and TEP production, and 4) to model coccolithophorid dynamics and their impact on ocean dissolved inorganic carbon (DIC) chemistry