Collaborative Research: GEOTRACES Arctic Section: Determination of atmospheric wet and dry deposition and air-sea exchange of mercury species from coastal to offshore waters

在该项目中，一组参加2015年美国GEOTRACES北极考察的调查人员将测量北冰洋大气中汞的浓度。与国际GEOTRACES计划中的其他多国倡议一样，美国北极考察的目标是确定控制海洋中关键微量元素和同位素分布的过程和量化通量，并确定这些分布对环境条件变化的敏感性。一些微量元素是生命所必需的，另一些是已知的生物毒素，还有一些是重要的，因为它们可以用作海洋中各种物理，化学和生物过程的示踪剂。汞，主要是甲基汞，是一种通过水生食物网进行大量生物累积的元素，并影响人类和野生动物的神经功能，因此，了解汞对该区域的输入至关重要。作为本研究的一部分，教育活动包括培训和指导本科生和研究生以及博士后研究人员。研究人员还将向当地北极社区开展有关汞影响的公共宣传活动。在北冰洋，自给性当地渔民和几种北极野生动物，如白鲸、海豹和北极熊，其体内的甲基汞含量通常较高。大气沉降是汞以湿沉降和干沉降（气溶胶和气态离子汞）形式进入海洋环境的主要途径。因此，测量汞并更好地了解其在北冰洋的循环至关重要。这项研究将进一步了解空气和表面沃茨（包括雪/冰、融化池和表面海水）中汞形态形成的驱动因素，以及这些浓度和其他物理和生物因素如何影响海气界面的沉积速率。将进行的主要测量包括从船上对开放水域和北冰洋海冰环境进行汞测量的基线，并将其与同期和历史沿海测量以及模型研究进行比较。总体而言，研究结果将提供必要的关键数据和信息，以了解人类活动和气候变化在加剧或改善北冰洋人类和野生动物接触甲基汞方面的作用。

In this project, a group of investigators participating in the 2015 U.S. GEOTRACES Arctic expedition will measure concentrations of atmospherically-derived mercury in the Arctic Ocean. In common with other multinational initiatives in the International GEOTRACES Program, the goals of the U.S. Arctic expedition are to identify processes and quantify fluxes that control the distributions of key trace elements and isotopes in the ocean, and to establish the sensitivity of these distributions to changing environmental conditions. Some trace elements are essential to life, others are known biological toxins, and still others are important because they can be used as tracers of a variety of physical, chemical, and biological processes in the sea. Mercury, primarily as methylmercury, is an element that substantially bioaccumulates through aquatic food webs and impacts neurological functions in humans and wildlife, and it is therefore critical to understand the inputs of mercury to the region. Educational activities as part of this study include training and mentoring of undergraduate and graduate students and a postdoctoral researcher. Researchers will also conduct public outreach activities about mercury impacts to local Arctic communities. In the Arctic Ocean, subsistence local fishermen and several species of Arctic wildlife, such as beluga whales, seals and polar bears, commonly have elevated levels of methylmercury in their system. Atmospheric deposition is the major pathway of mercury input to the marine environment as both wet and dry (aerosol and gaseous ionic mercury) deposition. Therefore, measurements of mercury and a better understanding of its cycling in the Arctic Ocean are critical. This study will provide further understanding of the drivers of mercury speciation in air and surface waters, including snow/ice, melt ponds, and surface seawater and how these concentrations, and other physical and biological factors, impact deposition rates at the air-sea interface. The primary measurements to be made include a baseline of mercury measurements over the open water from the ship, and over sea-ice environments of the Arctic Ocean, which will be compared to simultaneous and historic coastal measurements, as well as model studies. Overall, results will provide the crucial data and information necessary to comprehend the role of human activity and climate change in exacerbating or ameliorating the exposure of humans and wildlife to methylmercury in the Arctic Ocean.