Collaborative Research: U.S. GEOTRACES GP17-OCE and GP17-ANT: Thorium-230, Thorium-232 and Protactinium-231 tracers of trace element supply and removal

合作研究：美国GEOTRACES GP17-OCE和GP17-ANT：Thorium-230、Thorium-232和Protactinium-231微量元素供应和去除示踪剂

• 批准号: 2048863
• 负责人: Christopher Hayes
• 金额: $ 46.18万
• 依托单位: University of Southern Mississippi
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-07-01 至 2024-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2048863&HistoricalAwards=false
• 关键词: Collaborative; Research; U.S.; GEOTRACES; GP17

The goal of the international GEOTRACES program is to understand the distributions of trace chemical elements and their isotopes in the oceans. Many trace elements are essential for life and are thought to limit biological productivity throughout much of the ocean. This limitation, in turn, partly controls the ability of the ocean to support other marine life as well as the ocean's capacity to absorb carbon dioxide from the atmosphere. This project will provide constraints on the processes that supply and remove trace elements in the South Pacific Ocean and Amundsen Sea which are currently not well quantified. Naturally occurring radioactive isotopes such as thorium-230 and protactinium-231, which will be measured as a part of this work, can be utilized as proxies to provide critical information about the processes that supply iron and other micronutrient elements, as well as the rates of those processes. The isotope thorium-232 will also be utilized as a tracer of the supply of elements that are added to the ocean through the deposition of aerosol dust and from coastal sediments. These rates and fluxes can be used to improve our understanding of the micro-nutrient iron and the sinking fluxes of carbon which are both critical in the global carbon cycle. Outreach and broader impacts will be achieved through undergraduate and graduate teaching, community events such as the Ocean Sciences Bowl and other efforts through the international GEOTRACES program. This project will provide support for four collaborating labs (University of Southern Mississippi, University of Minnesota, Lamont-Doherty at Columbia University and CalTech) to undertake measurements on two US GEOTRACES cruises in the South Pacific, known as GP17 (GP17-OCE running from Tahiti south to the marginal sea ice zone and GP17-ANT focusing on the Amundsen margin). The PIs will measure dissolved and particulate concentrations of Th-230 and Pa-231. In addition, they will measure dissolved and particulate Th-232 concentrations and analyze a limited number of aerosol samples, aerosol leachates, colloidal size fractions and surface sediments for these radionuclides. They will be used to quantify trace element supply, including sedimentary inputs from the Amundsen Sea’s glacial meltwater pump and atmospheric dust inputs in one of the world’s lowest dust input regions. Additionally, the team will be able to quantify trace element removal, including sinking particulate fluxes for carbon, as well as trace elements, and scavenging characteristics of variable particle composition regimes. These goals also contribute to assessing Th and Pa as key palaeoceanographic proxies.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

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。许多痕量元素对生命至关重要，被认为可以限制整个海洋的生物生产力。反过来，这种限制部分控制着海洋支持其他海洋生物的能力以及海洋从大气中吸收二氧化碳的能力。该项目将对供应和删除南太平洋和阿蒙森海的痕量元素的过程提供限制，这些元素目前尚未得到很好的量化。可以将天然存在的放射性同位素（例如Thorium-230和Protectinium-231）作为这项工作的一部分进行衡量，可用作代理，以提供有关提供铁和其他微量营养元素的过程以及这些过程的速度。同位素-232的同位素也将被用作通过气溶胶粉尘和沿海沉积物的沉积中添加到海洋中的元素供应的示踪剂。这些速率和通量可用于提高我们对微营养铁和碳的下沉通量的理解，这在全球碳循环中都是至关重要的。通过本科和研究生教学，海洋科学碗等社区活动以及其他国际地理学计划的努力将实现外展和更广泛的影响。 This project will provide support for four collaborating labs (University of Southern Mississippi, University of Minnesota, Lamont-Doherty at Columbia University and CalTech) to undertake measurements on two US GEOTRACES cruises in the South Pacific, known as GP17 (GP17-OCE running from Tahiti south to the marginal sea ice zone and GP17-ANT focusing on the Amundsen margin). PI将测量Th-230和PA-231的溶解和颗粒浓度。此外，它们将测量溶解和颗粒的Th-232浓度，并分析有限数量的气溶胶样品，气溶胶叶甲酸盐，胶体尺寸的分数以及这些放射线的表面沉积物。它们将用于量化痕量元素供应，包括来自阿蒙森海冰川融水泵的沉积输入，以及世界上最低的灰尘输入区域之一的大气灰尘输入。此外，该团队将能够量化痕量元素的去除，包括碳的颗粒液磁通以及微量元素以及可变粒子组成制度的清除特征。这些目标还有助于评估TH和PA作为关键的古生物学代理。该奖项反映了NSF的法定任务，并通过使用基金会的知识分子优点和更广泛的影响审查标准来评估被认为是宝贵的支持。