US GEOTRACES GP17-OCE and GP17-ANT: Particulate and biogenic trace elements in the South Pacific and Southern Ocean

国际地学研究计划的目标是了解海洋中痕量化学元素及其同位素的分布。许多微量金属，如铁、锰和锌，是生命所必需的，也是浮游植物的营养物质。然而，太平洋和南大洋区域的铁和锰浓度很低，特别是有时会限制浮游植物的生长。该项目将增进对这些地区浮游植物吸收和去除微量营养素金属的了解。该项目将实现三个主要目标：1)测量从塔希提岛到智利的邮轮期间从南太平洋和南大洋上游区域收集的颗粒中磷和11种痕量金属的浓度；2)直接测量从这些水域收集的浮游植物细胞中这些元素的子集以及碳、硫和硅；以及3)测量从南极沿海水域采集的浮游植物中的相同元素。两名本科生实习生和一名博士后学者将参与该项目。科学成果和研究经验将通过两个班级与其他本科生分享，该项目将通过项目期间制作的虚拟现实游戏和相关活动向更广泛的公众介绍，并通过图书馆和机构外联活动进行介绍。美国地质遗迹GP17-OCE探险计划于2022年底进行，旨在确定横跨对营养和碳循环具有全球重要性的地区的横断面上微量元素和同位素的分布，横跨南太平洋环流、南极绕极流的限铁水域、具有热液输入的太平洋深海以及智利边缘附近的水域。南太平洋环流和南太平洋部分是全球海洋内热量、碳和营养物质转移的气候关键区域，浮游植物的生长通常受到表层海洋中铁(Fe)浓度较低的限制。研究人员将使用电感耦合等离子体质谱和同步加速器x射线荧光显微镜来解决三个主要研究问题，这些问题集中在该地区微量元素的内部生物地球化学循环：1)优势浮游植物类群的微量元素含量如何响应环境中的常量营养素和微量元素梯度？2)各种颗粒物组分的微量元素组成(成岩、自生、3)颗粒物的组成和化学计量如何影响痕量元素循环和微量元素：周围水团的营养化学计量？该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

The goal of the international GEOTRACES program is to understand the distributions of trace chemical elements and their isotopes in the oceans. Many trace metals, such as iron, manganese and zinc, are essential for life and serve as nutrients for phytoplankton. However, regions of the Pacific and Southern Oceans have very low concentrations of iron and manganese, in particular, limiting the growth of phytoplankton at times. This project will improve understanding of the uptake and removal of micronutrient metals by phytoplankton in these regions. This project will accomplish three main objectives: 1) measure the concentrations of phosphorus and eleven trace metals in particles collected from the upper region of the South Pacific and Southern Oceans during a cruise from Tahiti to Chile; 2) measure a subset of these elements, along with carbon, sulfur and silicon, directly in phytoplankton cells collected from these waters; and 3) measure the same elements in phytoplankton collected from coastal Antarctic waters on a subsequent, companion cruise into the Amundsen Sea. Two undergraduate student interns will be involved in the project, along with a postdoctoral scholar. The scientific results and research experience will be shared with additional undergraduates through two classes, and the project will be brought to the broader public through a virtual reality game and associated activities produced during the project and introduced through libraries and institutional outreach events.The U.S. GEOTRACES GP17-OCE expedition, planned for late 2022, aims to determine the distribution of trace elements and isotopes along a transect spanning regions of global importance to nutrient and carbon cycling, crossing the South Pacific Gyre, the iron-limited waters of the Antarctic Circumpolar Current, Pacific Deep Waters with hydrothermal inputs, and waters near the Chilean margin. The South Pacific Gyre and Pacific sector of the Southern Ocean are climate-critical regions for the transfer of heat, carbon, and nutrients within the global ocean, and they are a region where phytoplankton growth is typically limited by low concentrations of iron (Fe) in the surface ocean. The researchers will use inductively-coupled plasma mass spectrometry and synchrotron x-ray fluorescence microscopy to address three primary research questions focused on the internal biogeochemical cycling of trace elements in this region: 1) How do trace element contents of dominant phytoplankton taxa respond to environmental macronutrient and trace element gradients? 2) How does the trace element composition of the various particulate matter fractions (lithogenic, authigenic, biogenic) vary across the section? 3) How does the composition and stoichiometry of particulate material influence trace element cycling and trace element:nutrient stoichiometry of the surrounding water masses?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.