Sources and exchanges of mercury in the waters of the Northwestern Mediterranean margin

The Hg from the open sea water is the largest Hg input to the Gulf of Lions (∼5.7 kmol yr−1), whereas inputs from the riverine source account for ∼3.4 kmol yr−1 and atmospheric deposition for less than 0.5 kmol yr−1. The Hg accumulated in the sediments of the shelf is ∼4.5 kmol yr−1, including 0.6-1.7 kmol yr−1 in the Rhône prodelta sediments. The evasion to the atmosphere represents a Hg flux of ∼2.6 kmol yr−1.