GEOTRACES Arctic Section: Determining the Pathways, Fate, and Flux of Atmospherically Derived Trace Elements in the ocean/ice system

GEOTRACES 北极部分：确定海洋/冰系统中大气衍生微量元素的路径、命运和通量

• 批准号: 1434085
• 负责人: David Kadko
• 金额: $ 36.99万
• 依托单位: Florida International University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-10-01 至 2018-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1434085&HistoricalAwards=false
• 关键词: GEOTRACES; Arctic; Section; Determining; Pathways

In this project, a group of investigators participating in the 2015 U.S. Arctic GEOTRACES expedition will study the areal and depth distribution of Beryllium-7 in the western and central Arctic Ocean. Beryllium-7 (chemical symbol 7Be) is a harmless, naturally-occurring radioisotope (half-life = 53 days) generated worldwide in the upper atmosphere by cosmic ray interaction with certain atmospheric gases. It continuously falls to the Earth's surface, especially during precipitation events, where it can be used as a convenient tracer for a wide variety of environmental processes. It is expected to be very useful in helping to meet the goals of the U.S. Arctic GEOTRACES expedition: namely, 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. Working alongside a multi-institutional team of ocean trace element experts, the work of the 7Be research group should enable the team to determine the importance of atmospheric deposition of aerosols as a pathway for delivering trace elements from the continents to the deep Arctic Ocean and also to study how the presence or absence of surface sea ice influences the behavior of trace elements in the water column. Like many other participants in the expedition, the 7Be researchers plan to train graduate students in their research and to be involved in public educational outreach efforts in coastal communities in Alaska.This project will address three priority tasks formulated within the International GEOTRACES Science and Arctic Implementation Plans. First, it will provide realistic estimates of the underlying transport processes influencing distributions of many trace elements of interest (TEIs). Water column measurements of 7Be will be used as a tracer of physical mixing processes, which redistribute biologically active species in the upper water column. Quantitative knowledge of the circulation, mixing, and ventilation of the water masses within which TEIs reside allows an assessment of the time- and space-integrated in situ biogeochemical behavior of these elements. Secondly, 7Be will be used to trace the partitioning of atmospherically deposited elements within the Arctic catchments. The Arctic is unique to other GEOTRACES basins studied to date. For numerous TEIs, measurement not only in the water column, but also in the additional repositories of ice, snow and melt ponds is critical. The inventory of 7Be within these catchments will be used to trace the partitioning of atmospherically deposited elements within the Arctic ocean/ice system. Thirdly, 7Be data will be used to improve methods for quantifying the atmospheric deposition of TEIs. Measurements of 7Be in the surface waters and in the lower atmosphere will be used to develop estimates of the atmospheric input of relevant TEIs. In the Arctic, aerosol deposition is an important pathway for delivering trace element species, but assessment of this input has heretofore proven to be difficult.

在该项目中，一组参加2015年美国北极GEOTRACES考察的调查人员将研究Bernion-7在北冰洋西部和中部的区域和深度分布。 铍-7（化学符号7 Be）是一种无害的天然放射性同位素（半衰期= 53天），通过宇宙射线与某些大气气体的相互作用在世界各地的高层大气中产生。 它不断福尔斯到地球表面，特别是在降水事件期间，在那里它可以用作各种环境过程的方便示踪剂。 预计它将有助于实现美国北极GEOTRACES考察的目标：即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。 与海洋微量元素专家的多机构团队一起工作，7 Be研究小组的工作应使该团队能够确定气溶胶的大气沉积作为将微量元素从大陆输送到北冰洋深处的途径的重要性，并研究表面海冰的存在与否如何影响水柱中微量元素的行为。 像许多其他参与探险的人一样，7 Be的研究人员计划在他们的研究中培训研究生，并参与阿拉斯加沿海社区的公共教育推广工作。该项目将解决国际GEOTRACES科学和北极实施计划中制定的三项优先任务。 首先，它将提供现实的估计的基本运输过程影响分布的许多微量元素的利益（TEI）。水柱测量7 Be将被用作物理混合过程的示踪剂，该过程重新分配上层水柱中的生物活性物种。定量知识的流通，混合，和通风的水体内TEIs居住允许评估的时间和空间集成在原位地球化学行为的这些元素。 其次，7 Be将被用来跟踪北极集水区内的大气沉积元素的分区。北极是迄今为止所研究的其他GEOTRACES盆地所独有的。对于许多TEI，不仅在水柱中进行测量，而且在冰、雪和融化池的附加储存库中进行测量也是至关重要的。这些集水区内的库存7 Be将被用来跟踪北极海洋/冰系统内的大气沉积元素的分区。 第三，7 Be数据将用于改进量化TEI大气沉积的方法。7 Be在地表沃茨和低层大气中的测量将被用来开发相关TEIs的大气输入的估计。在北极，气溶胶沉积是一个重要的途径，提供微量元素的物种，但评估这一输入迄今已被证明是困难的。