Collaborative Research: US GEOTRACES GP17-ANT: Dissolved concentrations, isotopes, and colloids of the bioactive trace metals

合作研究：美国 GEOTRACES GP17-ANT：生物活性痕量金属的溶解浓度、同位素和胶体

• 批准号: 2123491
• 负责人: Seth John
• 金额: $ 39.8万
• 依托单位: University of Southern California
• 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: 2021-10-01 至 2024-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2123491&HistoricalAwards=false
• 关键词: Collaborative; Research; US; GEOTRACES; GP17

The goal of the international GEOTRACES program is to understand the distributions of trace chemical elements and their isotopes (TEIs) in the oceans. Many trace metals such as iron are essential for life and thus considered nutrients for phytoplankton growth, with trace metal cycling being especially important for influencing carbon cycling in the iron-limited Southern Ocean, where episodic supply of iron from a range of different external sources is important. The primary goal of this project is to measure the dissolved concentrations, size partitioning, and dissolved isotope signature of Fe on a transect of water-column stations throughout the Amundsen Sea and surrounding region of the Antarctic Margin, as part of the GP17-ANT Expedition. The secondary goal of this project is to analyze the concentrations and size partitioning of the trace metals manganese, zinc, copper, cadmium, nickel, and lead in all water-column samples, measure the isotope ratios of zinc, cadmium, nickel, and copper in a subset of water column samples, and measure the Fe isotopic signature of aerosols, porewaters, and particles. Observations from this project will be incorporated into regional and global biogeochemistry models to assess TEI cycling within the Amundsen Sea and implications for the wider Southern Ocean. This project spans three institutions, four graduate students, undergraduate students, and will provide ultrafiltered samples and data to other PIs as service.The US GEOTRACES GP17 ANT expedition, planned for austral summer 2023/2024 aims to determine the distribution and cycling of trace elements and their isotopes in the Amundsen Sea Sector (100-135°W) of the Antarctic Margin. The cruise will follow the Amundsen Sea ‘conveyor belt’ by sampling waters coming from the Antarctic Circumpolar Current onto the continental shelf, including near the Dotson and Pine Island ice shelves, the productive Amundsen Sea Polynya (ASP), and outflowing waters. Episodic addition of dissolved Fe and other TEIs from dust, ice-shelves, melting ice, and sediments drive seasonal primary productivity and carbon export over the Antarctic shelf and offshore into Southern Ocean. Seasonal coastal polynyas such as the highly productive ASP thus act as key levers on global carbon cycling. However, field observations of TEIs in such regions remain scarce, and biogeochemical cycling processes are poorly captured in models of ocean biogeochemistry. The investigators will use their combined analytical toolbox, in collaboration with the diagnostic chemical tracers and regional models of other funded groups to address four main objectives: 1) What is the relative importance of different sources in supplying Fe and other TEIs to the ASP? 2) What is the physiochemical speciation of this Fe, and its potential for transport? 3) How do biological uptake, scavenging and regeneration in the ASP influence TEI distributions, stoichiometry, and nutrient limitation? 4) What is the flux and signature of TEIs transported offshore to the ACC and Southern Ocean?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 GEOTRACES 计划的目标是了解海洋中微量化学元素及其同位素 (TEI) 的分布。许多微量金属（例如铁）对于生命至关重要，因此被认为是浮游植物生长的营养物质，尤其是微量金属循环。对于影响铁有限的南大洋的碳循环非常重要，该项目的主要目标是测量溶解浓度、尺寸分配和铁的分布。作为 GP17-ANT 探险的一部分，该项目的第二个目标是分析整个阿蒙森海和南极边缘周边地区水柱站横断面的铁溶解同位素特征。所有水柱样品中的痕量金属锰、锌、铜、镉、镍和铅，测量锌、镉、镍、该项目的观测结果将纳入区域和全球生物地球化学模型，以评估阿蒙森海内的 TEI 循环及其对更广泛范围的影响。南大洋。该项目横跨三个机构，四名研究生、本科生，并将向其他PI提供超滤样本和数据作为服务。美国GEOTRACES GP17 ANT探险队，计划于 2023/2024 年夏季进行，旨在确定南极边缘阿蒙森海区（西经 100-135°）的微量元素及其同位素的分布和循环。该巡航将沿着阿蒙森海“传送带”进行采样。来自南极绕极流流入大陆架的水域，包括靠近多特森和派恩岛冰架、多产的阿蒙森海冰间湖 (ASP) 以及来自灰尘、冰架、融化的冰和沉积物的溶解铁和其他 TEI 的间歇性添加推动了南极大陆架和近海到南大洋的季节性初级生产力和碳输出。由于高产的 ASP 因此成为全球碳循环的关键杠杆，然而，这些地区的 TEI 的实地观测仍然很少，而且海洋模型中很难捕捉到生物地球化学循环过程。研究人员将使用他们的组合分析工具箱，与其他资助团体的诊断化学示踪剂和区域模型合作来实现四个主要目标：1）不同来源在向 ASP 提供铁和其他 TEI 方面的相对重要性是什么。 2) 这种铁的物理化学形态是什么，及其运输潜力是什么？ 3) ASP 中的生物吸收、清除和再生如何影响 TEI 分布、化学计量和营养物质？ 4) 海上运输到 ACC 和南大洋的 TEI 的通量和特征是什么？该奖项反映了 NSF 的法定使命，并通过使用基金会的智力优点和更广泛的影响审查标准进行评估，被认为值得支持。