US GEOTRACES GP17-ANT: Dissolved Gallium, Barium, and Vanadium as interface, process, and circulation tracers in the Amundsen Sea

国际 GEOTRACES 计划的目标是了解海洋中微量化学元素和同位素的分布。通过在协调的探险中测量微量元素和同位素，海洋学家可以了解控制其输入、输出和在海洋中运动的过程。美国国家科学基金会正在支持 2023 年至 2024 年在南大洋和阿蒙森海进行的美国 GEOTRACES 采样考察。该项目将重点关注溶解的镓、钡和钒的测量，以推断多个过程，例如不同水类型的分布（如冰川融水或温暖的海水）、微量元素的沉积物供应，以及生物生产力对该采样不足区域的金属循环的影响。该项目将支持一名早期职业调查员和一名本科生研究员，并将通过几项计划外展活动与公众分享结果。本研究将利用过滤的海水和海冰样本，使用同位素稀释和 ICP-MS 方法来确定溶解的镓、钡和钒的浓度。利用溶解的镓、钡和钒与其他感兴趣参数（例如铁和铝）的相对比例的分布，本研究将研究：（1）海冰过程如何通过物质供应、吸收和再矿化与水柱微量元素循环相交叉； (2) 局部沉积过程（还原性沉积物与非还原性沉积物）如何影响微量元素的区域分布； (3)除了历史上使用的示踪剂之外，是否可以使用线性混合方法（除了历史上使用的示踪剂之外还加入溶解的镓）来限制该地区不同水类型的循环。因此，这项研究将评估阿蒙森海水与近海区域的连通性、冰间湖对地球化学循环的影响，以及来自陆地、冰冻圈、沉积物和海洋输入的微量元素的相对供应。这些观点在阿蒙森海尤其重要，因为阿蒙森海是气候引起的该地区冰盖快速不稳定的场所，而且阿蒙森海与形成深水的罗斯海和影响全球水团化学的多产区域环极地流相连。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 isotopes in the oceans. By measuring trace elements and isotopes on coordinated expeditions, oceanographers can learn about processes that control their inputs, outputs, and movement through the ocean. The National Science Foundation is supporting a U.S. GEOTRACES sampling expedition in the Southern Ocean and Amundsen Sea in 2023-2024. This project will focus on the measurement of dissolved gallium, barium, and vanadium to infer several processes such as the distribution of different water types – like glacial meltwater or warm ocean water – sediment supply of trace elements, and the effects of biological productivity on metal cycling in this under-sampled region. The project will support an early career investigator and an undergraduate student researcher and results will be shared with the public through several planned outreach activities.Utilizing filtered seawater and sea ice samples, this study will use isotope-dilution and ICP-MS methodology to determine concentrations of dissolved gallium, barium, and vanadium. Leveraging distributions of dissolved gallium, barium, and vanadium in their relative ratios with other parameters of interest (e.g., iron and aluminum) this study will investigate: (1) how sea ice processes intersect with water column trace element cycling through material supply, uptake, and remineralization; (2) how local sedimentary processes (reductive versus non-reductive sediments) influence the regional distribution of trace elements; and (3) if a linear-mixing approach, with dissolved gallium in addition to historically used tracers, can be used to constrain circulation of different water types in this region. This study will thus assess the connectivity of Amundsen Sea waters to the off-shelf region, the influence of polynyas on geochemical cycles, and the relative supply of trace elements from terrestrial, cryosphere, sedimentary, and oceanic inputs. These points are particularly pertinent in the Amundsen Sea as a locus of rapid, climate-induced destabilization of the region’s ice sheets and since the Amundsen Sea has connectivity with the Ross Sea, where deep waters are formed, and the circumpolar current, a productive region that influences the chemistry of global 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.