Patterns and controls of mercury accumulation in sediments from three thermokarst lakes on the Arctic Coastal Plain of A
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Aquatic Sciences
RESEARCH ARTICLE
Patterns and controls of mercury accumulation in sediments from three thermokarst lakes on the Arctic Coastal Plain of Alaska S. M. Burke1 · C. E. Zimmerman2 · B. A. Branfireun3 · J. C. Koch2 · H. K. Swanson1 Received: 10 May 2017 / Accepted: 14 November 2017 © Springer International Publishing AG, part of Springer Nature 2017
Abstract The biogeochemical cycle of mercury will be influenced by climate change, particularly at higher latitudes. Investigations of historical mercury accumulation in lake sediments inform future predictions as to how climate change might affect mercury biogeochemistry; however, in regions with a paucity of data, such as the thermokarst-rich Arctic Coastal Plain of Alaska (ACP), the trajectory of mercury accumulation in lake sediments is particularly uncertain. Sediment cores from three thermokarst lakes on the ACP were analyzed to understand changes in, and drivers of, Hg accumulation over the past ~ 100 years. Mercury accumulation in two of the three lakes was variable and high over the past century (91.96 and 78.6 µg/ m2/year), and largely controlled by sedimentation rate. Mercury accumulation in the third lake was lower (14.2 µg/m2/year), more temporally uniform, and was more strongly related to sediment Hg concentration than sedimentation rate. Sediment mercury concentrations were quantitatively related to measures of sediment composition and VRS-inferred chlorophyll a, and sedimentation rates were related to various catchment characteristics. These results were compared to data from 37 previously studied Arctic and Alaskan lakes. Results from the meta-analysis indicate that thermokarst lakes have significantly higher and more variable Hg accumulation rates than non-thermokarst lakes, suggesting that certain properties (e.g., thermal erosion, thaw slumping, low hydraulic conductivity) likely make lakes prone to high and variable Hg accumulation rates. Differences and high variability in Hg accumulation among high latitude lakes highlight the complexity of predicting future climate-related change impacts on mercury cycling in these environments. Keywords Mercury · Thermokarst · Paleolimnology · Alaska · Lake · Sediment
Introduction
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00027-017-0553-0) contains supplementary material, which is available to authorized users. * H. K. Swanson [email protected] S. M. Burke [email protected] 1
Department of Biology, University of Waterloo, Waterloo, ON, Canada
2
US Geological Survey, Alaska Science Center, Anchorage, AK, USA
3
Department of Biology and Centre for Environment and Sustainability, University of Western Ontario, London, Canada
Mercury (Hg), in an organic, methylated form (monomethylmercury; MeHg), is a neurotoxicant that bioaccumulates and biomagnifies through aquatic food webs (see Kidd et al. 1995; Atwell et al. 1998; Lockhart et al. 2005), and can reach concentrations in fish that are harmful to fish-eating wildl
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