Characterization of the distribution and properties of inert copper in seawater

铜是一种重要的营养物质，但在高浓度和某些化学形式下对水生生物也是有毒的。因此，了解海水中铜的化学形态对于了解其对海洋生态系统的影响非常重要。首席研究员之前对北太平洋和北大西洋中铜的研究结果表明，海洋中溶解的大多数铜（Cu）是惰性的，可能不会与海水中的其他化合物进行化学交换。铜似乎只在地表水中以惰性形式释放出来，在那里它被光介导的反应分解。在这个项目中，研究小组将确定太平洋和哥伦比亚河样本中海水中惰性和不稳定形式铜的交换速率和过程。该项目还旨在了解海水中溶解的有机物如何在海洋环流的时间尺度上与铜发生反应。该项目包括通过南加州大学青年研究人员计划为洛杉矶中南部地区的高中生提供夏季研究机会，该计划在整个夏季为学生提供导师。研究机会将提供给本科生从事实验室为基础的交换动力学工作。该研究项目挑战了目前的范式，即铜在海水中的形态和分布是由强大的、不稳定的有机配合物主导的，这些有机配合物可以通过热力学平衡来表征。该项目的目标包括：1)确定惰性池和不稳定池之间的Cu交换速率；2)表征太平洋和哥伦比亚河样品中惰性和惰性Cu的稳定同位素组成；3)了解惰性Cu与溶解有机质的关系。该团队将努力重新评估对海水中铜的化学性质的理解，并确定控制其循环和生物可用性的过程和机制。这项工作将扩大以前使用的方法，以分离惰性铜在反相柱加上色谱分离。研究结果将为更详细的结构表征提供基础，并为将基于物种的天然同位素丰度数据纳入Cu生物地球化学模型提供基础。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。

Copper is an important nutrient but also toxic to aquatic organisms at high concentrations and in certain chemical forms. Understanding the chemical forms of copper in seawater is therefore important to understanding its effect in ocean ecosystems. Results from the principal investigator’s previous research investigating copper in the North Pacific and North Atlantic Oceans indicated that most dissolved copper (Cu) in the ocean is inert and likely does not undergo chemical exchange with other compounds in seawater. It appears that Cu is only released from the inert form in surface waters, where it is decomposed by light-mediated reactions. In this project, the team will determine the rates and processes of exchange between inert and labile forms of copper in seawater in samples from the Pacific Ocean and Columbia River. The project also aims to understand how dissolved organic matter in seawater will react with copper over the timescales of ocean circulation. The project includes summer research opportunities for high school students in the South Central Los Angeles Area through a program known as USC Young Researchers Program that provides students with a mentor throughout the summer. Research opportunities will be provided to undergraduate students to work on laboratory-based exchange kinetics work. This research project challenges the current paradigm that copper speciation and distribution in seawater is dominated by strong, labile organic complexes that can be characterized by thermodynamic equilibria. The objectives of this project include: 1) determining rates of exchange of Cu between inert and labile pools, 2) characterizing the stable isotope composition of labile and inert Cu from samples collected from the Pacific Ocean and Columbia River, and 3) understanding the relationship between inert Cu and dissolved organic matter. The team will work to reassess the understanding of the chemistry of copper in seawater and determine the processes and mechanisms that control its cycling and biological availability. The work will expand the methodology utilized previously to isolation of inert Cu on reverse phase columns coupled with chromatographic separation. The results will provide a basis for more detailed structural characterization and provide a basis for including speciation-based natural isotope abundance data into models of Cu biogeochemistry.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.