Development of Methods for Direct Determinations of Carbonate Ion Concentrations in Seawater

该奖项是根据2009年《美国复苏和再投资法案》(公法111-5)资助的。过去两个世纪大气中二氧化碳浓度的上升导致海洋对二氧化碳的吸收增加。这一过程降低了上层海洋的pH值，降低了海洋碳酸盐离子浓度，从而降低了碳酸钙的饱和程度。如果这一趋势持续下去，将对珊瑚和一些浮游生物等关键海洋生物造成严重负面影响。鉴于碳酸盐离子浓度对海洋快速演化的碳酸盐系统的重要性，因此非常需要从派生的二氧化碳系统变量的等级转移到主要测量变量的列表。因此，南佛罗里达大学的一位科学家将开发一种新方法，直接在实验室、船上或现场测定碳酸盐离子浓度。当碳酸铅和一系列氯化铅络合物的相对浓度随溶解碳酸盐浓度的变化而变化时，该方法将通过对铅(II)吸收光谱的紫外光谱观察来获得碳酸盐离子浓度。此外，这位科学家计划通过船载分析来改进和提高碳酸盐离子分光光度测量的准确性。在船载分析中，除了传统最先进的总溶解无机碳、二氧化碳逸度和pH测量外，还使用紫外吸收光谱来计算碳酸盐离子浓度。至于更广泛的影响，该方法将为海洋科学界提供另一种更容易、更准确的方法来确定海水饱和状态(这既影响钙化速度，也影响碳酸盐溶解速度)。作为该项目的一部分，一名博士后和一名研究生将得到支持和培训。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Rising atmospheric carbon dioxide concentrations over the past two centuries have led to increasing carbon dioxide uptake by the oceans. This process, which is decreasing the pH of the upper ocean, is reducing oceanic carbonate ion concentrations and thus the level of saturation of calcium carbonate. If the trend continues, it will have a seriously negative impact on key marine organisms such as corals and some plankton. In view of the importance of carbonate ion concentrations to the oceans' rapidly evolving carbonate system, it is then highly desirable to move from the rank of derived carbon dioxide system variables to the list of primary measured variables. As such, a scientist from the University of South Florida will develop a new method to directly determine the carbonate ion concentrations in the laboratory, shipboard, or in-situ. The method would obtain carbonate ion concentrations with ultraviolet spectroscopic observations of Pb(II) absorbance spectra as the relative concentrations of lead carbonate and an ensemble of lead chloride complexes change in response to varying concentrations of dissolved carbonate. In addition, the scientist plans to refine and improve the accuracy of spectrophotometric carbonate ion measurements via shipboard analyses wherein carbonate ion concentrations are calculated using UV absorbance spectroscopy in addition to conventional state of the art measurements of total dissolved inorganic carbon, carbon dioxide fugacity, and pH.As regards broader impacts, the method will provide the ocean science community with another, perhaps easier and more accurate means of determining seawater saturation states (which influence both calcification rates and carbonate dissolution rates). One postdoc and one graduate student would be supported and trained as part of this project.