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TitleChanges in Arctic mercury levels - Processes affecting Hg transformations and biotic uptake
AuthorNerentorp, M; Wang, F; Jonsson, S; Cairns, W R L; Chetelat, J; Lescord, G; Ukonmaanaho, L; Outridge, PORCID logo; St Pierre, K; Obrist, D; Douglas, T A; Zdanowicz, C; Bravo, A G
SourceAMAP 2021 Arctic Mercury Science Assessment; Nature Reviews Earth & Environment 2020 p. 1-56 Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20200697
PublisherArctic Monitoring and Assessment Programme, Tromso, Norway
Mediapaper; on-line; digital
File formatpdf
Lat/Long WENS-180.0000 -1.0000 90.0000 60.0000
Subjectsmercury; mercury geochemistry; mineral deposits; glaciers; oceanography; Arctic Basin
Illustrationsschematic diagrams; location maps; distribution diagrams; tables
ProgramEnvironmental Geoscience Program Management
Released2020 09 17
Summary(Plain Language Summary, not published)
Large amounts of Hg, primarily as gaseous elemental Hg, are transported to the Arctic environment annually via the atmosphere, while even larger amounts of inorganic Hg are brought into the Arctic Ocean via ocean currents and rivers. Globally significant amounts of mostly natural Hg are also stored within the Arctic in permafrost soils. These permafrost stocks of Hg are now at risk of being remobilized into the modern biogeochemical cycle as the Arctic warms and thaws. Thus, the majority of Hg in the Arctic environment exists in inorganic forms. A small fraction of the inorganic Hg is converted to monomethylmercury (MeHg) in ocean waters, coastal sediments, and wetland soils. After uptake of MeHg at the base of aquatic food webs, MeHg can biomagnify up food webs to concentrations of toxicological concern. The potential risk Hg pollution poses to Arctic ecosystems is thus not only controlled by the amounts of inorganic Hg transported into the system and cycling within the Arctic environment, but also to what extent the Hg pool is methylated and accumulated in aquatic food webs. In this chapter, key processes are described that link the Hg transported to, and mobilized within, the Arctic environment to the Hg accumulated in Arctic biota, including the wildlife important as northern wild foods. Processes covered include Hg methylation pathways, methylating genes, the role of organic matter in controlling the amounts of Hg methylated, Hg demethylation pathways, and the potential role of dimethylmercury in the Arctic Hg cycle. Uptake and subsequent biomagnification of MeHg in aquatic food webs is then described. Finally, a first-order mass balance estimate of MeHg in the Arctic environment is provided.

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