Large subglacial source of mercury from the southwestern margin of the Greenland Ice Sheet
Large subglacial source of mercury from the southwestern margin of the Greenland Ice Sheet
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DOI：
10.1038/s41561-021-00753-w
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发表时间：
2021-05-24
影响因子：
18.3
通讯作者：
Spencer, Robert G. M.
中科院分区：
文献类型：
--
作者：
Hawkings, Jon R.;Linhoff, Benjamin S.;Spencer, Robert G. M.
格陵兰冰盖目前没有计入北极汞预算，尽管每年流入海洋的汞量很大且不断增加，而且北极生物体内的高汞含量引起了社会经济方面的关切。在这里，我们目前的汞浓度从格陵兰冰盖的西南边缘的三个冰川集水区的融水和评估出口的汞下游峡湾的基础上，在夏季消融季节收集的样本。我们发现，溶解汞的浓度是自然沃茨中记录的最高浓度之一，这些冰川集水区的汞产量（521- 3，300 mmol km（-2）年（-1））比北极河流（4-20 mmol km（-2）年（-1））高两个数量级。据估计，格陵兰岛西南部地区的溶解汞通量在全球范围内具有重要意义（15.4-212千摩尔年（-1）），约占全球河流通量的10%，其中包括生物累积性甲基汞的出口（0.31-1.97千摩尔年（-1））。高溶解汞浓度（类似于20 pM无机汞和类似于2 pM甲基汞）被发现持续跨越峡湾的盐度梯度。平均颗粒汞浓度是文献中记录的最高浓度之一（类似于51，000 pM），径流中的溶解汞浓度超过了报告的表面冰雪值。这些结果表明，在冰盖床汞的地质来源。高浓度的汞及其向下游峡湾的大量出口对北极生态系统具有重要影响，这突出表明迫切需要更好地了解全球变暖下冰盖径流中的汞动态。
The Greenland Ice Sheet is currently not accounted for in Arctic mercury budgets, despite large and increasing annual runoff to the ocean and the socio-economic concerns of high mercury levels in Arctic organisms. Here we present concentrations of mercury in meltwaters from three glacial catchments on the southwestern margin of the Greenland Ice Sheet and evaluate the export of mercury to downstream fjords based on samples collected during summer ablation seasons. We show that concentrations of dissolved mercury are among the highest recorded in natural waters and mercury yields from these glacial catchments (521-3,300 mmol km(-2) year(-1)) are two orders of magnitude higher than from Arctic rivers (4-20 mmol km(-2) year(-1)). Fluxes of dissolved mercury from the southwestern region of Greenland are estimated to be globally significant (15.4-212 kmol year(-1)), accounting for about 10% of the estimated global riverine flux, and include export of bioaccumulating methylmercury (0.31-1.97 kmol year(-1)). High dissolved mercury concentrations (similar to 20 pM inorganic mercury and similar to 2 pM methylmercury) were found to persist across salinity gradients of fjords. Mean particulate mercury concentrations were among the highest recorded in the literature (similar to 51,000 pM), and dissolved mercury concentrations in runoff exceed reported surface snow and ice values. These results suggest a geological source of mercury at the ice sheet bed. The high concentrations of mercury and its large export to the downstream fjords have important implications for Arctic ecosystems, highlighting an urgent need to better understand mercury dynamics in ice sheet runoff under global warming.