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Tundra uptake of atmospheric elemental mercury drives Arctic mercury pollution

Obrist, Daniel and Agnan, Yannick and Jiskra, Martin and Olson, Christine L. and Colegrove, Dominique P. and Hueber, Jacques and Moore, Christopher W. and Sonke, Jeroen E. and Helmig, Detlev. (2017) Tundra uptake of atmospheric elemental mercury drives Arctic mercury pollution. Nature, 547 (7662). pp. 201-204.

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Official URL: https://edoc.unibas.ch/68585/

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Abstract

Anthropogenic activities have led to large-scale mercury (Hg) pollution in the Arctic. It has been suggested that sea-salt-induced chemical cycling of Hg (through 'atmospheric mercury depletion events', or AMDEs) and wet deposition via precipitation are sources of Hg to the Arctic in its oxidized form (Hg(ii)). However, there is little evidence for the occurrence of AMDEs outside of coastal regions, and their importance to net Hg deposition has been questioned. Furthermore, wet-deposition measurements in the Arctic showed some of the lowest levels of Hg deposition via precipitation worldwide, raising questions as to the sources of high Arctic Hg loading. Here we present a comprehensive Hg-deposition mass-balance study, and show that most of the Hg (about 70%) in the interior Arctic tundra is derived from gaseous elemental Hg (Hg(0)) deposition, with only minor contributions from the deposition of Hg(ii) via precipitation or AMDEs. We find that deposition of Hg(0)-the form ubiquitously present in the global atmosphere-occurs throughout the year, and that it is enhanced in summer through the uptake of Hg(0) by vegetation. Tundra uptake of gaseous Hg(0) leads to high soil Hg concentrations, with Hg masses greatly exceeding the levels found in temperate soils. Our concurrent Hg stable isotope measurements in the atmosphere, snowpack, vegetation and soils support our finding that Hg(0) dominates as a source to the tundra. Hg concentration and stable isotope data from an inland-to-coastal transect show high soil Hg concentrations consistently derived from Hg(0), suggesting that the Arctic tundra might be a globally important Hg sink. We suggest that the high tundra soil Hg concentrations might also explain why Arctic rivers annually transport large amounts of Hg to the Arctic Ocean.
Faculties and Departments:05 Faculty of Science > Departement Umweltwissenschaften
UniBasel Contributors:Jiskra, Martin
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:Nature Research
ISSN:0028-0836
e-ISSN:1476-4687
Note:Publication type according to Uni Basel Research Database: Journal article
Language:English
Identification Number:
Last Modified:13 Feb 2019 09:17
Deposited On:13 Feb 2019 09:17

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