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

向地表水提供铁和其他生物必需的微量元素是南大洋生物生长的关键调节器。海冰体积和南大洋的物理动力学目前正在经历快速变化。了解金属循环的相应变化是必要的，因为这些元素是浮游植物生长所必需的，浮游植物在调节大气CO2中起着重要作用。其中一个主要的知识缺口是了解这些金属的可溶形式是如何产生并运输到海洋表面的。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，使金属保持在溶液中，否则它们会在其来源附近沉淀。目前，人们对这些配体是什么、它们来自哪里、它们如何影响南大洋中金属的反应性和命运知之甚少。本文提出的研究旨在确定与金属结合的有机配体，并确定南极大陆边缘的配体来源和反应性。该项目将调查六种重要的生物微量元素（铁、铜、锌）的分子形态。Ni, Co, Mn)沿着美国GEOTRACES巡航轨道沿着阿蒙森海的南极大陆架，以便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，研究人员将评估生态系统从南极环极流的低生产力缺铁条件向沿上升流大陆边缘的高生产力转变时的生物配体生产，并特别关注阿蒙森海多冰华和下沉的有机物质再矿化带的生产。其次，当水穿过南极大陆架并接受沉积物和冰川融水的输入时，将测量环极深水中配体的积累、饱和度和组成的变化。最后，研究了海冰对金属配体动力学的影响。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，本项目的结果将为这些模型提供提供配体和影响配体浓度的过程的知识。作为该项目的一部分，将支持和培训两名研究生和本科生实习生。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。

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.