Collaborative Research: US GEOTRACES GP-17-ANT: Molecular speciation of trace element-ligand complexes in the Southern Ocean and Antarctic shelf

向表层沃茨提供铁和其他生物必需微量元素是南大洋生物生长的重要调节因素。南大洋的海冰量和物理动态目前正在经历迅速变化。需要了解金属循环的相应变化，因为这些元素对浮游植物的生长至关重要，而浮游植物在调节大气CO2中起着重要作用。主要的知识差距之一是了解这些金属的可溶形式是如何产生和运输到海洋表面的。许多微量元素不溶于海水，除非它们与溶解的有机分子或配体结合，否则会在其来源附近沉淀。目前对这些配体是什么，它们来自哪里，或者它们如何影响南大洋金属的反应性和命运知之甚少。本研究的目的是确定与金属结合的有机配体，并确定配体的来源和反应性沿着南极大陆边缘。 该项目将调查六种生物重要微量元素（Fe，Cu，Zn）的分子形态。镍，钴，锰）沿着美国GEOTRACES巡航轨道沿着阿蒙森海的南极大陆架，以更好地了解该地区的微量元素循环。GEOTRACES考察的目标是确定控制微量元素及其同位素向南大洋分布的过程和量化通量。作为这项工作的一部分，研究人员将评估生物配体的生产，因为生态系统从南极绕极流的低生产力铁饥饿条件转变为沿着上升大陆边缘的高生产力，特别关注评估阿蒙森海冰间湖水华和下沉有机物矿化带内的生产。第二，在环极深水中的配体的积累，饱和度和组成的变化将被测量的水穿过南极大陆架，并从沉积物和冰川融水接收输入。最后，海冰对金属配体动力学的作用将进行研究。金属配体是预测和估计金属分布的数值海洋模型的中心参数，该项目的结果将为这些模型提供有关供应配体和影响配体浓度的过程的知识。作为该项目的一部分，两名研究生和本科生实习生将得到支持和培训。该奖项反映了NSF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。

The supply of iron and other biologically essential trace elements to surface waters is a critical regulator of biological growth in the Southern Ocean. Sea ice volume and the physical dynamics of the Southern Ocean are currently experiencing rapid changes. An understanding of the corresponding changes in metal cycling is needed as these elements are essential for the growth of phytoplankton which plays an important role in modulating atmospheric CO2. One of the major knowledge gaps is understanding how soluble forms of these metals are generated and transported to the surface ocean. Many trace elements are insoluble in seawater and precipitate close to their sources unless they are bound to a dissolved organic molecule, or ligand, that keeps the metal in solution. Little is currently known about what these ligands are, where they come from, or how they affect the reactivity and fate of metals in the Southern Ocean. The study proposed here is designed to identify the organic ligands that bind to metals and determine the ligand sources and reactivity along the Antarctic continental margin. The proposed project will survey the molecular speciation of six biologically important trace elements (Fe, Cu, Zn. Ni, Co, Mn) along the US GEOTRACES cruise track along the Antarctic shelf in the Amundsen Sea in order to better understand trace element cycling across the region. The goal of the GEOTRACES expedition is to identify processes and quantify fluxes that control the distributions of trace elements and their isotopes to the Southern Ocean. As part of this effort, the investigators will assess biological ligand production as the ecosystem shifts from low productivity iron-starved conditions in the Antarctic Circumpolar Current to higher productivity along the upwelling continental margin, with a particular focus on assessing production within the Amundsen Sea polynya blooms and sinking organic matter remineralization zones. Second, changes in the accumulation, saturation, and composition of ligands in Circumpolar Deep Water will be measured as the water passes across the Antarctic shelf and receives inputs from sediments and glacial meltwaters. Finally, the role of sea ice on metal-ligand dynamics will be investigated. Metal ligands are a central parameter of numerical ocean models that predict and estimate metal distributions, and results from this project will provide those models with knowledge of the processes that supply ligands and affect ligand concentrations. Two graduate students and undergraduate interns will be supported and trained as part of this project.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.