Collaborative Research: US GEOTRACES PMT: Sources and Rates of Trace Element and Isotope Cycling Derived from the Radium Quartet

合作研究：美国 GEOTRACES PMT：源自镭四重奏的微量元素和同位素循环的来源和速率

• 批准号: 1736321
• 负责人: Willard Moore
• 金额: $ 11.3万
• 依托单位: University of South Carolina at Columbia
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-02-01 至 2024-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1736321&HistoricalAwards=false
• 关键词: Collaborative; Research; US; GEOTRACES; PMT

The goal of the international GEOTRACES program is to understand the distributions of trace chemical elements and their isotopes in the oceans. Naturally occurring radioactive isotopes of the element radium can be used to measure the rates of important processes in the ocean. In turn, making these rate measurements at the same time as other trace element and isotope data are collected enables a more complete interpretation of these data. The investigators propose to measure the four isotopes of radium -- Ra-223, Ra-224, Ra-226, and Ra-228 -- on a U.S. GEOTRACES expedition from Alaska to Tahiti in 2018. The radium isotope data will be particularly useful in investigating trace element input and removal processes associated with ocean boundaries (rivers, continental shelves, and the ocean bottom) and with mid-ocean ridge hydrothermal vents and the long-range dispersal of their neutrally buoyant plumes. The investigators will also investigate the processes controlling the internal cycling of the longest-lived isotope, Ra-226, compared to the element barium, which has a very similar chemistry to radium. The proposed work would address a number of key questions regarding trace element inputs from ocean boundaries and their potential impact on ocean productivity and biogeochemistry. As iron is an important nutrient for marine phytoplankton, the investigators will quantify the rates of lateral trace element transport from the Gulf of Alaska margin out to and including the offshore High Nutrient Low Chlorophyll region of the subarctic Northeast Pacific Ocean. In the ocean subsurface, they will seek to understand the trace element fluxes associated with high temperature hydrothermal venting, and the rate at which trace elements and isotopes are removed via scavenging along the hydrothermal plume. Lastly, the work will lead to an improved understanding of a marine carbonate sediment dating technique via an investigation of Ra-226 and barium fractionation processes in the upper ocean. The project will involve collaboration between two U.S. institutions and a partner in France who will analyze some of the samples. Two graduate students will participate in the project. Moore will supervise an undergraduate student through the South Carolina Alliance for Minority Participation, and will encourage this student to develop a senior thesis based on their participation in this project.

国际地理计划计划的目标是了解痕量化学元件及其同位素在海洋中的分布。元素辐射的天然放射性同位素可用于测量海洋重要过程的速率。反过来，收集其他痕量元素和同位素数据的同时进行这些速率测量值，可以对这些数据进行更完整的解释。调查人员建议在2018年在美国从阿拉斯加到塔希提岛的美国地理位置探险进行radium的四个同位素 - RA-223，RA-224，RA-226和RA-228 - 在美国的地理位置探险中。它们中性浮力羽毛的远距离散布。研究人员还将研究控制最长的同位素RA-226内部循环的过程，与元素钡相比，该过程与半径非常相似。拟议的工作将解决有关海洋边界中痕量要素投入的许多关键问题及其对海洋生产力和生物地球化学的潜在影响。由于铁是海洋浮游植物的重要营养素，研究人员将量化从阿拉斯加缘延伸到近海的横向痕量元件运输速率，包括近海的高营养高营养低营养低叶绿素叶绿素。在海洋地下，他们将寻求了解与高温水热通风相关的痕量元件通量，以及通过沿热液羽流清除去除微量元件和同位素的速率。最后，这项工作将通过RA-226的投资和上海上的钡分馏过程提高对海洋碳酸盐沉积物约会技术的了解。该项目将涉及两家美国机构与法国合作伙伴之间的合作，他们将分析一些样本。两名研究生将参加该项目。摩尔将通过南卡罗来纳州联盟（South Carolina Alliance）进行少数派参与的本科生监督，并鼓励该学生根据他们参与该项目的高级论文。