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

点击翻译按钮获取中文摘要

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.