Collaborative Research: U.S. GEOTRACES North Atlantic Section: Analysis of 230Th, 232Th and 231Pa

合作研究：美国 GEOTRACES 北大西洋剖面：230Th、232Th 和 231Pa 分析

• 批准号: 0927754
• 负责人: Richard Edwards
• 金额: $ 40.5万
• 依托单位: University of Minnesota-Twin Cities
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-04-01 至 2014-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0927754&HistoricalAwards=false
• 关键词: Collaborative; Research; U.S.; GEOTRACES; North

In this project four collaborating labs -- Woods Hole Oceanographic Institution, University of Rhode Island, University of Minnesota and Lamont-Doherty -- will undertake measurements on the US GEOTRACES North Atlantic section of the dissolved and particulate concentrations of 230Th and 231Pa, two isotopes designated as "key" or critical to the success of the GEOTRACES program. In addition, they will measure 232Th concentrations and provide supporting analyses of particle composition. The proposed work fulfills scientific objectives defined in the U.S. GEOTRACES North Atlantic Implementation Plan. These new 231Pa, 230Th and 232Th data are expected to lead to improved models of material exchange between the boundaries and interior Atlantic on a basin-wide scale. This project will permit the research team and the marine radiogeochemical community to test hypotheses regarding the relative importance of regional variations in circulation, particle composition, and particle flux that influence the redistribution of particle-associated elements, including carbon, trace metals and contaminants, between the continental shelf/slope regions and interior basins in the Atlantic. Furthermore, obtaining new water column 231Pa and 230Th data will allow testing of a key hypothesis: that 230Th is largely removed within the North Atlantic, whereas nearly half of the 231Pa produced in-situ is exported with North Atlantic Deep Water. Sedimentary 231Pa/230Th ratios have become the principal proxy used to evaluate past changes in Atlantic Meridional Overturning Circulation (AMOC). Completing the proposed work will characterize the importance of particle composition for 231Pa/230Th fractionation, and thereby constrain the potential bias in using 231Pa/230Th as a kinematic proxy for AMOC. These results, in turn, will lead to a more reliable assessment of the role of AMOC variability in past climate change. Broader Impacts The hypotheses and objectives outlined in this proposal are central to the International GEOTRACES program, whose focus is on the global-ocean distribution of trace elements and isotopes in seawater. 231Pa and 230Th are designated key parameters in the GEOTRACES Science Plan as their measurement on all sections is deemed to be critical to the success of this international ocean science program. The proposed research will provide new opportunities for graduate student (LDEO) and post doc (UMinn) research experience, enhance ocean science interactions between several US institutions (LDEO, URI, UMinn, WHOI), foster collaboration with international GEOTRACES colleagues, and contribute to existing science education programs designed for teachers and the public.

在该项目中，伍兹霍尔海洋研究所、罗德岛大学、明尼苏达大学和拉蒙特-多尔蒂大学等四个合作实验室将在美国 GEOTRACES 北大西洋部分测量 230Th 和 231Pa 的溶解和颗粒浓度，这两种同位素被指定为“关键”或对 GEOTRACES 计划成功至关重要的两种同位素。此外，他们还将测量 232Th 浓度并提供颗粒成分的支持分析。拟议的工作实现了美国 GEOTRACES 北大西洋实施计划中定义的科学目标。这些新的 231Pa、230Th 和 232Th 数据预计将改进全盆地范围内边界和内大西洋之间的物质交换模型。该项目将使研究小组和海洋放射地球化学界能够测试关于环流、颗粒组成和颗粒通量的区域变化的相对重要性的假设，这些变化影响着颗粒相关元素（包括碳、痕量金属和污染物）在大西洋大陆架/斜坡区域和内陆盆地之间的重新分布。此外，获得新的水柱 231Pa 和 230Th 数据将能够检验一个关键假设：230Th 大部分在北大西洋内被去除，而原位产生的 231Pa 的近一半随北大西洋深水输出。沉积物 231Pa/230Th 比率已成为用于评估大西洋经向翻转环流 (AMOC) 过去变化的主要代理。完成拟议的工作将表征颗粒组成对于 231Pa/230Th 分馏的重要性，从而限制使用 231Pa/230Th 作为 AMOC 运动学代理的潜在偏差。这些结果反过来将有助于对 AMOC 变异性在过去气候变化中的作用进行更可靠的评估。更广泛的影响 本提案中概述的假设和目标是国际 GEOTRACES 计划的核心，该计划的重点是海水中微量元素和同位素的全球海洋分布。 231Pa 和 230Th 被指定为 GEOTRACES 科学计划中的关键参数，因为它们在所有剖面上的测量被认为对于这一国际海洋科学计划的成功至关重要。拟议的研究将为研究生（LDEO）和博士后（UMinn）的研究经验提供新的机会，加强美国多个机构（LDEO、URI、UMinn、WHOI）之间的海洋科学互动，促进与国际 GEOTRACES 同事的合作，并为现有的为教师和公众设计的科学教育项目做出贡献。