Mercury in the Atlantic Ocean: factors controlling air–sea exchange of mercury and its distribution in the upper waters

To understand further the cycling of mercury at the earthʹs surface we discuss the results of recent measurements of Hg concentration and speciation in the upper ocean and marine boundary layer of the Atlantic Ocean. In water, dissolved gaseous Hg (DGHg) and total Hg measurements are reported; for the atmosphere, total gaseous Hg, reactive gaseous Hg (RGHg) and particulate Hg measurements were made. These measurements allow estimation of gas evasion to the atmosphere and deposition to the ocean. In conjunction with the field collections, incubation experiments both on board ship and in the laboratory have examined further the processes controlling the oxidation and reduction of Hg species in water. Our results suggest that dry deposition of RGHg. could be significant.