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Mercury export from Arctic great rivers

March 2, 2020

Land–ocean linkages are strong across the circumpolar north, where the Arctic Ocean accounts for 1% of the global ocean volume and receives more than 10% of the global river discharge. Yet estimates of Arctic riverine mercury (Hg) export constrained from direct Hg measurements remain sparse. Here, we report results from a coordinated, year-round sampling program that focused on the six major Arctic rivers to establish a contemporary (2012–2017) benchmark of riverine Hg export. We determine that the six major Arctic rivers exported an average of 20 000 kg y–1 of total Hg (THg, all forms of Hg). Upscaled to the pan-Arctic, we estimate THg flux of 37 000 kg y–1. More than 90% of THg flux occurred during peak river discharge in spring and summer. Normalizing fluxes to watershed area (yield) reveals higher THg yields in regions where greater denudation likely enhances Hg mobilization. River discharge, suspended sediment, and dissolved organic carbon predicted THg concentration with moderate fidelity, while suspended sediment and water yields predicted THg yield with high fidelity. These findings establish a benchmark in the face of rapid Arctic warming and an intensifying hydrologic cycle, which will likely accelerate Hg cycling in tandem with changing inputs from thawing permafrost and industrial activity.

Publication Year 2020
Title Mercury export from Arctic great rivers
DOI 10.1021/acs.est.9b07145
Authors Scott Zolkos, David P. Krabbenhoft, Anya Suslova, Suzanne E. Tank, James W. McClelland, Robert G. M. Spencer, Alexander Shiklomanov, Alexander V. Zhulidov, Tatiana Gurtovaya, Nikita Zimov, Sergey Zimov, Edda A. Mutter, Les Kutny, Edwin Amos, Robert M. Holmes
Publication Type Article
Publication Subtype Journal Article
Series Title Environmental Science & Technology
Index ID 70211932
Record Source USGS Publications Warehouse
USGS Organization Upper Midwest Water Science Center