Hg Stable Isotope Time Trend in Ringed Seals Registers Decreasing Sea Ice Cover in the Alaskan Arctic

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• 作者：J茅r茅my Masbou ; David Point ; Jeroen E. Sonke ; Fr茅d茅ric Frappart ; Vincent Perrot ; David Amouroux ; Pierre Richard ; Paul R. Becker
• 刊名：Environmental Science & Technology
• 出版年：2015
• 出版时间：August 4, 2015
• 年：2015
• 卷：49
• 期：15
• 页码：8977-8985
• 全文大小：438K
• ISSN：1520-5851

文摘

Decadal time trends of mercury (Hg) concentrations in Arctic biota suggest that anthropogenic Hg is not the single dominant factor modulating Hg exposure to Arctic wildlife. Here, we present Hg speciation (monomethyl-Hg) and stable isotopic composition (C, N, Hg) of 53 Alaskan ringed seal liver samples covering a period of 14 years (1988鈥?002). In vivo metabolic effects and foraging ecology explain most of the observed 1.6 鈥?variation in liver 未²⁰²Hg, but not 螖¹⁹⁹Hg. Ringed seal habitat use and migration were the most likely factors explaining 螖¹⁹⁹Hg variations. Average 螖¹⁹⁹Hg in ringed seal liver samples from Barrow increased significantly from +0.38 卤 0.08鈥?(卤SE, n = 5) in 1988 to +0.59 卤 0.07鈥?(卤SE, n = 7) in 2002 (4.1 卤 1.2% per year, p < 0.001). 螖¹⁹⁹Hg in marine biological tissues is thought to reflect marine Hg photochemistry before biouptake and bioaccumulation. A spatiotemporal analysis of sea ice cover that accounts for the habitat of ringed seals suggests that the observed increase in 螖¹⁹⁹Hg may have been caused by the progressive summer sea ice disappearance between 1988 and 2002. While changes in seal liver 螖¹⁹⁹Hg values suggests a mild sea ice control on marine MMHg breakdown, the effect is not large enough to induce measurable HgT changes in biota. This suggests that Hg trends in biota in the context of a warming Arctic are likely controlled by other processes.