|Distribution and fluxes of calcium carbonate along the continental margin in the Gulf of Biscay|
Wollast, R.; Chou, L. (1998). Distribution and fluxes of calcium carbonate along the continental margin in the Gulf of Biscay. Aquat. Geochem. 4(3-4): 369-393
In: Aquatic Geochemistry. Springer/Springer Science+Business Media: London; Dordrecht; Boston. ISSN 1380-6165, more
Compositions of major components in suspended matter, collected by centrifugation, in situ pumping and sediment traps, in the Gulf of Biscay during the OMEX project were determined and compared. The results show a strong and rapid decrease in the concentration of biogenic fraction in the upper 200 m of the water column which may be attributed to the preferential removal of this component due to the production of faecal pellets and to the formation of marine snow. Concurrent decrease with depth of the organic and inorganic carbon contents demonstrate the importance of the respiration of organic matter and the dissolution of calcium carbonate in the oceanic carbon cycling. Lithogenic and carbonate fluxes across the continental slope in the Goban Spur area were evaluated based on sediment trap records. The rate of production of calcium carbonate in the surface waters (100 g CaCO3 m(-2)y(-1)), deduced from the primary production measurements, is much larger compared to the fluxes of this component observed in the sediment traps (5-21 g CaCO3 m(-2)y(-1)) and to its rate of burial (9-31 g CaCO3 m(-2) y(-1)). It strongly suggests the occurrence of carbonate dissolution, even in waters oversaturated with respect to the mineral phase considered. This is likely to be associated with the respiration of organic matter within the faecal pellets, or at the surface of biogenic calcite or aragonite.