Collaborative Research: US GEOTRACES GP17-ANT: Constraining the Neodymium (Nd) Isotope and Rare Earth Element Cycles near the Amundsen Sea Continental Margin

合作研究：美国 GEOTRACES GP17-ANT：限制阿蒙森海大陆边缘附近的钕 (Nd) 同位素和稀土元素循环

• 批准号: 2049554
• 负责人: Xinyuan Zheng
• 金额: $ 47.29万
• 依托单位: University of Minnesota-Twin Cities
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-06-15 至 2025-05-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2049554&HistoricalAwards=false
• 关键词: Collaborative; Research; US; GEOTRACES; GP17

Trace elements in seawater are relevant to climate and human society, because they can act as essential nutrients for marine ecosystems or useful chemical fingerprints for a variety of oceanographic processes. The international GEOTRACES program is intended to identify processes and quantify fluxes that control the distributions of key trace elements and their isotopes in the global ocean, and to establish how these distributions could respond to changing environments. Neodymium (Nd) isotopes and rare earth elements (REEs) are notable examples of such key elements because of their utility in tracing past and present ocean mixing and sources of trace elements to the ocean. In this project, investigators will participate in the US GEOTRACES science expedition GP17-ANT to the Amundsen Sea sector of the Antarctic continental margin, and analyze Nd isotope ratios and REE concentrations in samples collected from this expedition. This region of the ocean is of particular significance because it is experiencing rapid environmental changes in the past few decades, including the fastest melting of ice shelves around the entire Antarctic. Measurements from this project will advance our understanding of ocean processes that cause melting of local ice shelves, and also will shed new light on nutrient sources that sustain the unusually high biological productivity in the upper ocean of this region. This project will contribute to support the development of diverse involvement in Antarctic research, teaching and outreach efforts across career levels. The outreach activities will provide ample opportunities to engage K-12 students, students from underrepresented groups, and general public in discussions of ocean sciences and the Antarctic environment in both formal and informal settings.The US GEOTRACES GP17-ANT cruise to the Amundsen Sea provides an exceptional opportunity to study marine biogeochemical cycles of trace elements and their isotopes in relation to the Antarctic continental margin, fast iceshelf melting, productive polynyas, and water mass processes in an area especially susceptible to ongoing climate change. This project will study sources and processes that regulate the distribution of Nd isotopes and REEs in seawater in this region. Specific sources and processes that will be studied, and quantified where possible, include: (1) water mass transport and mixing; (2) slope exchange; (3) aerosols; (4) sea ice; (5) subglacial meltwaters; (6) sediments and shelf exchange; (7) particle interactions. Nd isotope and REE concentration analyses will be conducted on a suite of carefully selected seawater, particulate, sediment, aerosol, and sea ice samples to constrain the nature and relative significance of these different controls, providing a comprehensive understanding of Nd isotope and REE cycling in the Antarctic margin. These results will not only provide critical constraints on water mass processes and lithogenic inputs that are directly relevant to understand all other trace element biogeochemical cycles in this region, but also improve the utility of Nd isotopes and REE patterns as useful tracers for studies of modern and ancient oceans.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.

海水中的微量元素与气候和人类社会相关，因为它们可以作为海洋生态系统的必需营养素或各种海洋过程的有用化学指纹。国际GEOTRACES计划旨在识别控制全球海洋中关键微量元素及其同位素分布的过程和量化通量，并确定这些分布如何响应不断变化的环境。钕 (Nd) 同位素和稀土元素 (REE) 是此类关键元素的著名例子，因为它们可用于追踪过去和现在的海洋混合以及海洋微量元素的来源。在该项目中，研究人员将参加美国GEOTRACES科学考察GP17-ANT前往南极大陆边缘阿蒙森海段，并对本次考察采集的样本中的Nd同位素比率和稀土元素浓度进行分析。这个海洋区域具有特别重要的意义，因为它在过去几十年里经历着快速的环境变化，包括整个南极洲周围冰架融化最快的情况。该项目的测量结果将增进我们对导致当地冰架融化的海洋过程的理解，并且还将为维持该地区上层海洋异常高的生物生产力的营养源提供新的线索。该项目将有助于支持各个职业层面对南极研究、教学和外展工作的多元化参与。外展活动将为 K-12 学生、来自弱势群体的学生和公众提供充足的机会，让他们在正式和非正式场合参与海洋科学和南极环境的讨论。美国 GEOTRACES GP17-ANT 前往阿蒙森海的巡航提供了一个绝佳的机会，可以快速研究与南极大陆边缘相关的微量元素及其同位素的海洋生物地球化学循环。 特别容易受到持续气候变化影响的地区的冰架融化、生产性冰间湖和水团过程。该项目将研究调节该地区海水中 Nd 同位素和稀土元素分布的来源和过程。将进行研究并在可能的情况下进行量化的具体来源和过程包括： (1) 水质量输送和混合； (2)坡度交换； (3) 气溶胶； (4) 海冰； (5) 冰下融水； (6)沉积物和陆架交换； (7)粒子相互作用。将对一系列精心挑选的海水、颗粒物、沉积物、气溶胶和海冰样本进行 Nd 同位素和 REE 浓度分析，以限制这些不同对照的性质和相对重要性，从而全面了解南极边缘的 Nd 同位素和 REE 循环。这些结果不仅将为了解该地区所有其他微量元素生物地球化学循环直接相关的水团过程和成岩输入提供关键约束，而且还将提高 Nd 同位素和 REE 模式作为现代和古代海洋研究的有用示踪剂的效用。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进行评估，被认为值得支持 标准。

项目成果

Reversible scavenging and advection – Resolving the neodymium paradox in the South Atlantic

可逆清除和平流 — 解决南大西洋的钕悖论

• DOI: 10.1016/j.gca.2021.09.015
• 发表时间: 2021
• 期刊: Geochimica et Cosmochimica Acta
• 影响因子: 5
• 作者: Wang, Ruixue;Clegg, Josephine A.;Scott, Peter M.;Larkin, Christina S.;Deng, Feifei;Thomas, Alexander L.;Zheng, Xin-Yuan;Piotrowski, Alexander M.
• 通讯作者: Piotrowski, Alexander M.