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TitleClimate change and mercury in the Arctic: Abiotic interactions
AuthorChételat, J; McKinney, M A; Amyot, M; Dastoor, A; Douglas, T A; Heimbürger-Boavida, L -E; Kirk, J; Kahilainen, K K; Outridge, P MORCID logo; Pelletier, N; Skov, H; St. Pierre, K; Vuorenmaa, J; Wang, F
SourceScience of the Total Environment vol. 824, 153715, 2022 p. 1-17, Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20210697
Mediapaper; on-line; digital
File formatpdf
Subjectsmercury; mercury geochemistry; climate; permafrost; Climate change
Illustrationsphotographs; diagrams
ProgramEnvironmental Geoscience Program Management
Released2022 02 09
AbstractDramatic environmental shifts are occuring throughout the Arctic from climate change, with consequences for the cycling of mercury (Hg). This review summarizes the latest science on how climate change is influencing Hg transport and biogeochemical cycling in Arctic terrestrial, freshwater and marine ecosystems. As environmental changes in the Arctic continue to accelerate, a clearer picture is emerging of the profound shifts in the climate and cryosphere, and their connections to Hg cycling. Modeling results suggest climate influences seasonal and interannual variability of atmospheric Hg deposition. The clearest evidence of current climate change effects is for Hg transport from terrestrial catchments, where widespread permafrost thaw, glacier melt and coastal erosion are increasing the export of Hg to downstreamenvironments. Recent estimates suggest Arctic permafrost is a large global reservoir of Hg, which is vulnerable to degradation with climate warming, although the fate of permafrost soil Hg is unclear. The increasing development of thermokarst features, the formation and expansion of thaw lakes, and increased soil erosion in terrestrial landscapes are increasing river transport of particulate-bound Hg and altering conditions for aquatic Hg transformations. Greater organic matter transport may also be influencing the downstream transport and fate of Hg. More severe and frequent wildfires within the Arctic and across boreal regions may be contributing to the atmospheric pool of Hg. Climate change influences on Hg biogeochemical cycling remain poorly understood. Seasonal evasion and retention of inorganic Hg may be altered by reduced sea-ice cover and higher chloride content in snow. Experimental evidence indicates warmer temperatures enhance methylmercury production in ocean and lake sediments as well as in tundra soils. Improved geographic coverage of measurements andmodeling approaches are needed to better evaluate net effects of climate change and long-term implications for Hg contamination in the Arctic.
Summary(Plain Language Summary, not published)
Current evidence indicates climate change is significantly influencing certain aspects of mercury cycling in the Arctic. Arctic permafrost contains a globally-significant mercury reservoir, vulnerable to degradation and release into waterways. Permafrost thaw, glacier melt, and coastal erosion are increasing mercury export into lakes, rivers and ultimately the Arctic Ocean. More severe and frequent wildfires within the Arctic and across boreal regions may be contributing to the atmospheric concentration of mercury. Experiments show warmer temperatures increase methylmercury production in Arctic sediments and soils, which suggests the possibility of higher mercury concentrations in fish and wildlife. However, the overall net effects of climate change on Arctic mercury contamination remain poorly resolved.

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