Collaborative Research: US GEOTRACES Pacific Zonal Transect: Rates of supply, removal and internal cycling of trace elements and isotopes

GEOTRACES的目标是确定控制海洋中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。 虽然大量TEI的分布将由一个大型GEOTRACES PI团队沿该样带沿着绘制，但如果不同时测量示踪剂，则无法正确解释其分布，这些示踪剂能够提供边界和界面处的内部TEI循环过程和通量的速率。 天然存在的放射性同位素的铀钍系列非常适合于研究源和汇的TEI的时间和空间尺度上必要的解释横向和垂直TEI分布。在这个项目中，来自伍兹霍尔海洋研究所和哥伦比亚的南卡罗来纳州大学的一个研究小组将在前往东热带南太平洋的美国GEOTRACES巡航中对一套铀/钍系列放射性核素进行测量。 该放射性示踪剂套件将包括寿命较短的234 Th和228 Th以及镭四重态（224 Ra，223 Ra，228 Ra，226 Ra），它们共同允许量化水平和垂直传输和混合的速率，以及在海洋边界，表面输出和地下再矿化的去除率。更广泛的影响：PI积极参与本科生和高中生在他们以前的NSF资助的项目，有两个在ASLO会议上获奖，近年来。这一趋势将继续与这一努力，沿着包括一个国际客座学生谁将工作的分析改进测量颗粒228钍。此外，两名WHOI-MIT联合项目的学生将参与使用该项目作为他们关于Th和Ra同位素的博士论文的主要部分。这6种同位素对数据管理方面的贡献是建模界热切期待的，在这些流域尺度上缺乏多个钍同位素数据集，用于参数化所有粒子反应性和生物活性TEI的循环。

The goal of GEOTRACES is to identify processes and quantify fluxes that control the distribution of trace elements and isotopes (TEIs) in the ocean, and to establish the sensitivity of these distributions to changing environmental conditions. While the distribution of numerous TEIs will be mapped by a large team of GEOTRACES PIs along this transect, their distribution cannot be properly interpreted without concurrent measurement of tracers capable of providing rates of internal TEI cycling processes and fluxes at boundaries and across interfaces. Naturally-occurring radioisotopes of the Uranium-Thorium series are well suited for studying the sources and sinks of TEIs on time and space scales necessary to interpret lateral and vertical TEI distributions. In this project, a research team from the Woods Hole Oceanographic Institution and the University of South Carolina at Columbia will carry out measurement of a suite of uranium/thorium series radionuclides on the US GEOTRACES cruise to the Eastern Tropical South Pacific (ETSP) Ocean. This radiotracer suite will include shorter-lived 234Th and 228Th as well as the radium quartet (224Ra, 223Ra, 228Ra, 226Ra), which together allow the quantification of rates of horizontal and vertical transport and mixing, as well as removal at ocean boundaries, surface export, and subsurface remineralization. Broader Impacts: The PIs have actively involved undergraduate and high school students in their prior NSF-funded projects, with two having won awards at ASLO meetings in recent years. The trend will continue with this effort, along with the inclusion of an international guest student who will work on analytical improvements for measuring particulate 228Th. In addition, two WHOI-MIT Joint Program students will be involved using this project as a major part of their PhD theses on Th and Ra isotopes. Contributions to the data management side of the results from these 6 isotopes is eagerly awaited by the modeling community, where there is a lack of multiple thorium isotope data sets on these basin scales for parameterization of the cycling of all particle reactive and biologically active TEIs.