Résumé
In this paper, field experiments performed in the Bay of Brest on the French Atlantic Coast are presented as a contribution to the French PNEC program. Experiments were done in shallow waters using bcnthic chambers to determine benthic fluxes of mercury species together with major biological activities. Simultaneous determination of mercury compounds was performed by speciated isotope dilution mass spectrometry (SIDMS) allowing excellent precision and low detection limits for in situ benthic chainhers experiments. The results demonstrate that bcnthic fluxes of mercury species in such coastal environment are probably related to biological processes involved in surface sediments with significant time variability. They suggest that sediment-water exchanges of mercury species arc highly dynamic and driven by transient redox change at the sediment water interface.