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Arctic Sea-Ice Controls the Release of Mercury

January 23, 2011 1 comment

Mercury is the most high profile atmospheric contaminant entering the Arctic because it is a potent neurotoxin that biomagnifies in food webs. In the troposphere (lower atmosphere) it is primarily present in the form of gaseous elemental mercury. Photochemical reactions during the Arctic spring (Figure 1) combine salts from sea ice and the gaseous mercury in the air to create an oxidized reactive form of mercury. This mercury is then deposited to snow and ice. These deposition events require salty sea ice and snow crystal surfaces so they are widespread in the Polar Regions.

Mercury (Hg) is the only heavy metal that is essentially found in gaseous form in the atmosphere. Since the industrial revolution, emissions of anthropogenic Hg resulting from the combustion of fossil fuels have exceeded natural emissions. Both anthropogenic emissions and natural emissions (which mainly stem from the oceans and gases released by volcanoes) reach the Polar Regions under the action of atmospheric currents. In this way, fallout from global atmospheric pollution contributes to depositing mercury in Arctic ecosystems, even though these are far away from major anthropogenic emission sources. Read more…