Spectrophotometric Determinations of Carbonic Acid Dissociation Constants for Estuarine Conditions

河口条件下碳酸解离常数的分光光度测定

• 批准号: 2042935
• 负责人: Robert Byrne
• 金额: $ 33.96万
• 依托单位: University of South Florida
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-02-01 至 2025-01-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2042935&HistoricalAwards=false
• 关键词: Spectrophotometric; Determinations; Carbonic; Acid; Dissociation

Human health and well-being are linked in many ways to the health of our estuaries and coastal ocean waters. Yet surprisingly, we know less about some aspects of these important waters than we do the more distant waters of the deep ocean. This project will use state-of-the-art spectrophotometric methods (that is, light- and color-based methods) to advance our understanding of the fundamental and ever-changing chemistry of these waters and, eventually, the effects of these changes on marine life. The focus of this study will be to understand the chemistry of carbon dioxide in seawater. The new tools we will use are recently characterized pH indicators — chemicals that change color in seawater depending on the acidity of that water. These specially selected, purified indicators can be used to measure pH with unsurpassed precision and accuracy. We will use the indicators in laboratory experiments to determine how a critical parameter of the carbon dioxide system (a dissociation constant known as “K2”) changes depending on the temperature and salinity of the water. Characterizing K2 has been a goal of marine chemists for more than 50 years. The better we know K2, the better we can understand and predict how carbon moves through and cycles within natural waters. These measurements will expand our understanding of not only K2 but also the many other seawater characteristics that can be calculated from K2. Ultimately, this work will facilitate the interpretation and prediction of many ocean processes relevant to human health and coastal economies, such as ocean acidification (the lowering of ocean pH due to increasing carbon dioxide in the atmosphere) and calcium carbonate dissolution (the resulting dissolution of seashell material). The results will thus lay the groundwork for new perspectives on how ocean acidification affects the various shelled organisms that serve as food for economically important marine animals/fisheries and for people. The results of this work will also help to improve models of carbon dioxide dynamics in lakes, rivers, underground pore waters, and physiological fluids. As regards broader impacts, this work will help the PI continue to transfer his knowledge on this important topic to the next generation via his training of graduate, undergraduate, and high school students. This project would support one graduate and one undergraduate student, as well as help the current research projects of two minority doctoral students. Lastly, the PI plans to continue his involvement in the Bridge to the Doctoral Program aimed at getting minority students involved in the sciences.In seawater, two carbonic acid dissociation constants (K1 and K2) describe the relationship between solution pH and the relative concentrations of dissolved carbonate ions, bicarbonate ions, and dissolved carbon dioxide. Accurate characterization of these CO2-system constants over broad ranges of environmental conditions has been a much sought-after goal for more than 50 years because knowledge of these terms is essential for quantitatively interpreting and predicting the biogeochemical cycling of carbon in all natural aqueous systems. The accuracy of CO2-system calculations is especially sensitive to uncertainties in K2, the equilibrium constant that describes the dissociation of bicarbonate ions to produce hydrogen ions and carbonate ions. This research project is designed to use spectrophotometric pH measurements (solely) to characterize this important constant. The purified pH indicators to be used in this work provide seawater pH measurements of unsurpassed precision and accuracy. Using select indicators whose properties have recently been characterized over freshwater-to-seawater ranges of salinity and temperature, we will determine K2 over similar ranges so as to improve the accuracy of CO2-system calculations in estuaries and coastal ocean waters. The resulting insight into equilibrium characteristics will facilitate interpretations and predictions of pH buffering in aqueous systems, provide an improved understanding of calcium carbonate solubility behavior, and lead to improved models of CO2-system behavior in freshwater lakes, rivers, soil and sediment pore waters, and physiological fluids. The longer-term benefits of this project will extend to assessments of the influence of ocean acidification on the life cycles of carbonate-bearing organisms that serve as food for economically important marine organisms.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.

人类健康和福祉与我们的河口和沿海海水的健康有许多联系。然而，令人惊讶的是，我们对这些重要水域的某些方面了解少于我们在深海中更独特的水域。该项目将使用最先进的分光光度法方法（即基于浅色和颜色的方法）来促进我们对这些水域的基本和不断变化的化学的理解，最终，这些变化对海洋生物的影响。这项研究的重点是了解海水中二氧化碳的化学。我们将使用的新工具最近是pH指标的表征 - 根据水的酸度，可以在海水中改变颜色的化学物质。这些专门选择的纯化指标可用于以无与伦比的精度和准确性测量pH。我们将使用实验室实验中的指标来确定二氧化碳系统（称为“ K2”）的关键参数如何根据水的温度和盐度而变化。特征K2一直是海洋化学家的目标已有50多年了。我们知道K2越好，我们就越能理解并预测碳如何通过自然水域的移动和周期。这些测量值不仅会扩大我们对K2的理解，而且还将扩展我们对K2可以计算的许多其他海水特征。最终，这项工作将促进与人类健康和沿海经济相关的许多海洋过程的解释和预测，例如海洋酸化（由于大气中增加二氧化碳而导致的海洋pH降低）和碳酸钙溶解（导致盐材料的溶解）。因此，结果将为海洋酸化如何影响各种壳的生物，这些生物是经济上重要的海洋动物/渔业和人们的基础。这项工作的结果还将有助于改善湖泊，河流，地下孔隙水和物理烟道中二氧化碳动力学模型。关于广泛的影响，这项工作将通过培训毕业生，本科生和高中生，帮助PI继续将他对这一重要主题的知识转移到下一代。该项目将支持一名毕业生和一名本科生，并帮助两名少数族裔博士生的当前研究项目。最后，PI计划继续参与他的博士课程桥梁，旨在使少数族裔学生参与科学。这些二氧化碳系统常数在环境条件的广泛范围内的准确表征已成为50多年来的一个有意义的目标，因为这些术语的知识对于在所有天然水性系统中的定量解释和预测碳的生物地球化学循环至关重要。二氧化碳系统计算的准确性对K2中的不确定性特别敏感，K2的不确定性描述了碳酸氢盐离子以产生氢离子和碳酸盐离子的解离。该研究项目旨在使用分光光度法测量值（仅）来表征此重要常数。在这项工作中使用的纯化pH指标提供了无与伦比的精度和准确性的海水pH测量。使用盐至盐度和温度的淡水到盐水范围的特性的精选指标，我们将确定K2在相似范围上，以提高河口和沿海海水中二氧化碳计算的准确性。从而洞悉平衡特征将促进水性系统中pH缓冲的解释和预测，提供对碳酸钙溶解度行为的改进的理解，并改善淡水湖泊，河流，泥浆和沉积物孔隙水的CO2系统行为模型，并进行物理液体。该项目的长期益处将扩展到对海洋酸化对碳酸盐含量生命生命周期的影响的评估，这些生物是经济上重要的海洋生物的食物。该奖项反映了NSF的法定任务，并通过使用基金会的知识分子和更广泛的影响来审查审查标准来通过评估来诚实地通过评估来诚实地支持。