Exchange of Mercury between the Atmosphere and Snowpack in Western Hudson Bay: Cycles of Oxidation and Reduction

摘要

Wildlife in the western Hudson Bay ecoregion are showing signs of mercury (Hg) contamination. In the spring of 2003 we conducted snow surveys over western Hudson Bay to: 1) determine if atmospheric Hg depletion events are occurring in this sub Arctic region, and 2) determine the fate of deposited Hg(II) in snowpacks. We found that although extremely large quantities of Hg(II) were repeatedly deposited into snowpacks, this Hg(II) was quickly reduced to gaseous elemental Hg(0) and reemitted back to the atmosphere. Therefore, despite numerous springtime atmospheric Hg depletion events occurring in the region, only a very small fraction of the Hg(II) deposited from the atmosphere enters western Hudson Bay in snowmelt.