Collaborative Research: MEGA - Mercury biogeochemical cycling and export from Greenland to the Arctic

汞是一种与环境和人类健康有关的有毒元素。由于大气中的汞主要从矿区和工业区向北极输送，北极食物网中的汞含量特别高。北极汞的主要来源被认为是人类向大气排放的汞（例如，金矿开采中的材料加工和化石燃料燃烧），但也可能有大量的自然汞来源，可能随着气候变暖而变化。最近，格陵兰岛的冰川和冰原，大型的冰河，被确定为可能通过冰川物理研磨（当它们在景观中推平时）和融化向北极输送汞的来源，但数据仍然很少，这些现有的数据集突出了重大的不确定性。在MEGA项目中，研究人员将对(i)格陵兰岛的一系列冰川融水河流，（ii）这些融水流入的海洋，以及（iii）水样点附近的空气进行采样，以了解这些天然汞输入是否重要，以及/或是否可能随着气候变暖中冰川融化的增加而变化。这些新数据将提高我们对地球系统中冰川和冰盖重要性的认识，并利用现代测量技术提供关键的过程信息。MEGA项目最终将帮助我们了解汞如何在北极系统中移动和变化。MEGA将资助两名博士生、几名本科生和一些早期职业科学研究人员。它将在美国、丹麦、德国、捷克和格陵兰的研究人员之间建立国际合作，并为西费城资源不足的高中教师提供参与北极研究的独特机会。汞是一种有毒元素，在食物网中积累和放大，使其成为人类特别关注的问题。北极地区的汞浓度是决策者特别关注的问题，因为北极海洋生物中的汞浓度很高。这对于以捕鱼和狩猎为主要饮食来源的北极社区来说非常重要。北极汞的主要来源是低纬度地区人为汞的大气沉积（例如，手工金矿开采和化石燃料燃烧），这些汞通过盛行的大气环流输送到极地地区。最近，汞的自然来源，如永久冻土融化，作为北极汞循环的潜在重要组成部分，在气候变暖的情况下可能发生变化，受到了关注。然而，围绕这些对气候敏感但潜在重要的汞自然来源，特别是冰川和冰原，科学知识存在巨大差距。格陵兰冰盖是迄今为止北半球最大的冰块，覆盖了北极陆地表面的20%以上。最近的研究表明，冰盖可能是周围海洋生态系统中汞的重要来源，但数据有限，需要进一步的研究。MEGA项目将产生第一个完整的汞动员、运动和从源（冰）到汇（海洋）转变的模型。研究人员将通过采样(i)从冰盖流出的融水河流，（ii）这些河流进入的沿海地区，以及（iii）汞可能沉积/运输的大气，为格陵兰的汞制定一个强有力的数值预算。MEGA将使用创新的方法技术，如汞的化学指纹（例如，汞同位素比率）来提供信息，说明格陵兰冰盖过程在北极汞循环中的重要性。MEGA项目将支持各种各样的研究人员，包括本科生、两名研究生、一名早期职业博士后研究员和四名早期职业教师。该项目还将发展美国研究人员/机构与来自格陵兰、丹麦、捷克共和国和德国的研究人员/机构之间的合作、网络和能力建设。MEGA还将安排两名来自费城的K-12教育工作者进行实地考察，培养他们对STEM、北极研究和地球系统科学的兴趣，帮助启发他们的教学课程和学生。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Mercury is a toxic element that is of concern for the health of the environment and humans. There are particularly high amounts of mercury in Arctic food webs due to the transport of mercury in the atmosphere to the Arctic, primarily from mining and industrial regions. The main source of mercury to the Arctic is thought to be human emissions to the atmosphere (for example, from processing of material in gold mining and fossil fuel burning), but there may also be large natural sources of mercury that could change with climate warming. Glaciers and ice sheets, large rivers of ice, have recently been identified in Greenland as possible sources of mercury to the Arctic through glacier physical grinding (as they bulldoze their way through the landscape) and melt, but data is still sparse and these existing datasets highlight significant uncertainty. In the MEGA project, the investigators will sample (i) a range of glacial meltwater rivers across Greenland, (ii) the oceans these meltwaters flow into, and (iii) the air next to the water sampling sites, to understand whether these natural mercury inputs are important and/or are likely to change with increased glacier melting in a warming climate. This new data will improve our knowledge of the importance of glaciers and ice sheets in the Earth System, and provide critical process information using modern measurement techniques. The MEGA project will ultimately help us understand how mercury moves and changes through Arctic systems. MEGA will support two PhD students, several undergraduates, and a number of early career scientific researchers. It will establish an international collaboration between US, Danish, German, Czech and Greenlandic researchers, and provide unique opportunities for teachers from under resourced high schools in West Philadelphia to participate in Arctic research.Mercury is a toxic element that accumulates and magnifies in food webs, making it of particular concern to human populations. Concentrations of mercury in the Arctic region are of particular concern for policymakers because they are high in Arctic marine organisms. This is important for Arctic communities that rely on fishing and hunting for significant proportions of their diet. The major source of mercury to the Arctic is atmospheric deposition of anthropogenic mercury from lower latitudes (for example, from artisanal gold mining and fossil fuel burning), transported to the polar regions by prevailing atmospheric circulation. More recently, natural sources of mercury, such as from permafrost melting, have received attention as potentially important components of the Arctic mercury cycle that could change in a warming climate. However, large gaps in scientific knowledge surround these climatically sensitive but potentially significant natural sources of mercury, particularly glaciers and ice sheets. The Greenland Ice Sheet is by far the largest ice mass in the northern hemisphere, covering over 20% of the land surface in the Arctic. Recent research suggests the ice sheet may be an important source of mercury to surrounding ocean ecosystems, but the data is limited and additional research is needed. The MEGA project will produce the first complete model of mercury mobilization, movement and transformations from source (ice) to sink (ocean). The investigators will develop a robust numerical budget for mercury in Greenland by sampling (i) meltwater rivers flowing from the ice sheet, (ii) the coastal areas these rivers enter, and (iii) the atmosphere from where mercury can be deposited/transported. MEGA will use innovative methodological techniques like the chemical fingerprint of the mercury (e.g., mercury isotope ratios) to provide information that contextualizes the importance of the Greenland Ice Sheet processes in the Arctic mercury cycle. The MEGA project will support a diverse range of researchers, including undergraduate students, two graduate students, an early career postdoctoral researcher, and four early career faculty. The project will also develop collaborations, networking and capacity building between US researchers/institutions and researchers/institutions from Greenland, Denmark, the Czech Republic and Germany. MEGA will also embed two K-12 educators from Philadelphia in fieldwork to cultivate interests in STEM, Arctic research, and Earth systems science, helping inspire their teaching curriculum and their students.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.