MODELIZATION OF THE MERCURY FLUXES AT THE AIR-SEA INTERFACE

Aqueous and atmospheric Hg-degrees concentrations for remote marine areas such as the equatorial Pacific Ocean and for coastal seas such as the North Sea and the Scheldt Estuary are discussed. Biological processes seem to be at the origin of the supersaturated Hg-degrees concentrations in the water. On the other hand, transfer velocities across the air-sea interface were calculated with a classical shear turbulence model and with a wave breaking model. With these data, Hg-degrees fluxes from the sea to the atmosphere were calculated: in the Pacific Ocean they range from 0.43 to 6.5-mu-g Hg.m-2.yr-1 at a wind speed of 2.8 m.s-1 and from 10.3 to 156-mu-g Hg.m-2. yr-1 at a wind speed of 54 m.s-1, but they are still higher when wave breaking is considered (from 11 to 168-mu-g Hg.m-2.yr-1). These transfer fluxes are an order of magnitude higher in the Scheldt Estuary.