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

在这个项目中，参加2015年美国GEOTRACES北极考察队的一组调查人员将测量北冰洋中大气汞的浓度。与国际地质足迹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，并确定这些分布对不断变化的环境条件的敏感性。有些微量元素是生命所必需的，有些是已知的生物毒素，还有一些很重要，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大量生物积累并影响人类和野生动物神经功能的元素，因此了解汞对该地区的输入至关重要。作为这项研究的一部分，教育活动包括培训和指导本科生和研究生以及一名博士后研究员。研究人员还将开展有关汞对北极当地社区影响的公共宣传活动。在北冰洋，当地渔民和一些北极野生动物，如白鲸、海豹和北极熊，体内的甲基汞含量普遍偏高。大气沉降是汞进入海洋环境的主要途径，包括湿沉降和干沉降（气溶胶和气态离子汞）。因此，测量汞和更好地了解其在北冰洋的循环是至关重要的。这项研究将进一步了解空气和地表水（包括雪/冰、融化池和地表水）中汞物种形成的驱动因素，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。要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，这些测量将与同期和历史上的沿海测量以及模型研究进行比较。总体而言，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甲基汞暴露方面的作用。

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.