entering the ocean from drainage and river flows. Tundra soils are a major global mercury sink and the erosion of these soils appears to be the dominant source of mercury entering the Arctic Ocean (Obrist et al., 2018). Sea ice generally acts as a buffer to exchange between the air and the sea and mercury concentrations are higher under ice than in open waters. The loss of sea ice is likely to result in lower concentrations of mercury in some surface waters as more mercury is released into the atmosphere (DiMento et al., 2019). Increased atmospheric and ocean temperatures may also result in higher microbial activity and increased formation of methylmercury, an organic and highly poisonous type of mercury formed when bacteria react with mercury in water,
soil and plants (Angot et al., 2016). However, understanding the impact of climate change on an element as mobile as mercury is very difficult. There are many uncertainties and extensive research is required to understand the implications of predicted climatic changes on the environmental distribution of mercury. The Minamata Convention, together with national climate policies to reduce the use of coal, is expected to cut global mercury emissions (Maas and Grennfelt, 2016). However, any gains may be offset by the release of legacy mercury stored in tundra soils andpermafrost. If thismercury is released andenters the food web, it could result in dangerous contamination levels in the main sources of protein for humans, with devastating effects on food security in the Arctic.
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