Interpretation of AMAP Assessment Reports:mercury in the Arctic environment
The Arctic Monitoring and Assessment Programme(AMAP)Workgroup released a scientific assess-ment of"Mercury(Hg)in the Arctic"in 2021,which evaluated the contents and storages of Hg over Arctic en-vironmental media and predicted the potential future changes of Hg contents in Arctic environment based on the observational and modelling studies of Hg in Arctic environmental media from recent years.The report stated that global atmospheric Hg emissions originated mainly outside the Arctic(>98%),and some of which could be transported over long distances in the atmospheric circulation and deposited in Arctic ecosystems,where them participated in the biogeochemical cycling of Hg in the Arctic.The 2/3 of the Arctic atmospheric Hg was deposit-ed to terrestrial environments and 1/3 to marine environments.Hg in terrestrial environments was mainly stored in soils,glaciers,and snow,and could be transported to the Arctic Ocean by riverine transport and coastal ero-sion.Hg could also be transported into the Arctic Ocean by ocean currents.Hg stored in the Arctic Ocean could be removed by escaping into the atmosphere,burying on the continental shelf and in deep-sea basins,and out-flowing by ocean currents.The Arctic environmental Hg was predominantly in inorganic form and could be par-tially converted to methylmercury(MeHg)by microbial methylation processes in anaerobic environments.Re-ductions in primary emissions will have a greater impact on future changes of Hg contents in Arctic environment than climate change.And thus stringent and feasible global anthropogenic Hg reduction policies are needed to re-duce the ambient Hg levels in the Arctic over the next 20 years.The report also noted that in the future,better quantification of local Hg releases from the Arctic,enhanced research and modelling of key environmental pro-cesses for Hg,studies of microbial communities carrying Hg methylation and demethylation genes,consistent projections of primary emissions and climate change,and global inventories of anthropogenic Hg emissions are needed to accurately assess Hg cycling in the Arctic environment and predict changes in Arctic environmental Hg levels.
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