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: 2123333
• 负责人: Jessica Fitzsimmons
• 金额: $ 41.02万
• 依托单位: Texas A&M University
• 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=2123333&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项目的目标是了解海洋中痕量化学元素及其同位素（TEIs）的分布。许多微量金属，如铁，是生命所必需的，因此被认为是浮游植物生长的营养物，微量金属循环对于影响铁资源有限的南大洋的碳循环尤其重要，在南大洋，来自各种不同外部来源的间歇性铁供应很重要。该项目的主要目标是测量整个阿蒙森海和南极边缘周边地区水柱站的溶解浓度、大小分配和溶解同位素特征，作为GP17-ANT远征的一部分。该项目的第二个目标是分析所有水柱样品中微量金属锰、锌、铜、镉、镍和铅的浓度和大小分配，测量部分水柱样品中锌、镉、镍和铜的同位素比率，并测量气溶胶、孔隙水和颗粒的铁同位素特征。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循环及其对更广泛的南大洋的影响。该项目跨越3个机构，4名研究生，本科生，并将超滤样品和数据作为服务提供给其他pi。美国GEOTRACES GP17 ANT考察计划于2023/2024年夏季进行，旨在确定南极边缘阿蒙森海域（100-135°W）微量元素及其同位素的分布和循环。游轮将沿着阿蒙森海的“传送带”，从南极绕极流到大陆架的水域取样，包括多森和松岛冰架附近、生产丰富的阿蒙森海冰川（ASP）和流出的水域。来自尘埃、冰架、融化的冰和沉积物的溶解铁和其他TEIs的间歇性添加，推动了季节性初级生产力和碳向南极大陆架和南大洋近海的出口。因此，像高产的ASP这样的季节性海岸复殖区是全球碳循环的关键杠杆。然而，这些地区tei的实地观测仍然很少，海洋生物地球化学模型对生物地球化学循环过程的捕捉也很差。研究人员将使用他们的综合分析工具箱，与其他资助小组的诊断化学示踪剂和区域模型合作，解决四个主要目标：1)在向ASP提供铁和其他TEIs时，不同来源的相对重要性是什么？2)这种铁的物理化学形态是什么？它的运输潜力是什么？3) ASP的生物吸收、清除和再生如何影响TEI分布、化学计量和营养限制？4)外运至ACC和南大洋的tei的通量和特征是什么？该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。