Characterization of aragonite and calcite solubility products in seawater using modern CO2 system measurement techniques

使用现代 CO2 系统测量技术表征海水中文石和方解石溶解度产物

• 批准号: 1947489
• 负责人: Robert Byrne
• 金额: $ 40.59万
• 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: 2020
• 资助国家: 美国
• 起止时间: 2020-02-15 至 2025-01-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1947489&HistoricalAwards=false
• 关键词: Characterization; aragonite; calcite; solubility; products

Calcium carbonate is a mineral (solid) produced by economically and environmentally important types of marine organisms (including clams and oysters) for structural support and protection from predation. Calcium carbonate, the structural mineral of coral reefs, is becoming increasingly susceptible to dissolution (chemically-induced decomposition) due to the ocean’s uptake of carbon dioxide from the atmosphere. This project is devoted to improving the accuracy of predictions and interpretations of the stability of different forms of calcium carbonate that are uniquely important to the oceanic ecosystem. The stability or instability of solid calcium carbonate in seawater is routinely evaluated from (a) measurements of the concentrations of dissolved chemical components in collected seawater samples and (b) calculations (mathematical models) of the amounts of dissolved calcium and dissolved carbonate in seawater that are required to prevent solid calcium carbonate from dissolving. The necessary calculations for modeling calcium carbonate stability are generated from experiments in which solid calcium carbonate particles are added to seawater samples and the particles are allowed to dissolve until dissolution ends and no further changes in the particles are observed thereafter. The models of calcium carbonate stability in seawater produced through such experiments are important to the shellfish industry and are important to understanding the natural chemical cycles of carbonate-bearing organisms that serve as food for economically-important marine organisms. Over the past decade, the economic interests of the shellfish industry have stimulated monitoring efforts to assess day-to-day changes in the stability of calcium carbonate in hatchery waters. It is also recognized that models of calcium carbonate stability are important to understanding the availability of very small organisms in the surface ocean that serve as an essential food for early-life-stage salmon. Current models of the stability of solid calcium carbonate in seawater are more than thirty-five years old and were generated using measurement techniques that are considered antiquated by modern standards. Modern state-of-the-art methods will be used in this project to determine the chemical conditions required for stability of solid calcium carbonate in seawater, and these measurements will then be used to create quantitative models of calcium carbonate stability over a wide range of salinities and temperatures. For outreach activities, the scientist plans to communicate results from the study to the public via interactive modules at the St. Petersburg Science Festival and the Oceanography Camp for Girls, as well as prepare a presentation for the St. Petersburg SciCafe series about this project and how it relates to ocean acidification. This research will support the dissertation research of one graduate student and an undergraduate summer intern. This project is a state-of-the-art investigation of the solubility of calcium carbonate (CaCO3), a uniquely important mineral in the global ocean. Weathering of terrestrial CaCO3 minerals adds alkalinity to seawater in the form of bicarbonate (HCO3-) and carbonate [CO3(2-)]. Marine calcifiers at the ocean surface precipitate solid CaCO3 for structural support and protection from predation. The biogenic CaCO3 produced by marine calcifiers settles into and dissolves within deeper waters. These processes, sometimes called the calcium carbonate pump, are important for transferring carbon from the surface ocean to depth. As such, calcium carbonate, in both its solid form and dissolved components, plays an integral role in the global carbon cycle. Assessments of marine CaCO3 solubility are essential for a quantitative understanding and interpretation of transformations between solid CaCO3 and its dissolved components. CaCO3 solubility is quantitatively expressed in terms of the product (Ksp) of the dissolved Ca2+ and CO3(2-)concentrations (mol/kg seawater) in seawater at equilibrium with a specified crystalline polymorph of CaCO3. Ksp is influenced by seawater temperature (T), salinity (S), and pressure (P) and is used to quantify saturation state (Ω), the degree to which seawater is under- or over-saturated with dissolved Ca2+ and CO3(2-). In view of the decreasing saturation states of CaCO3 in the global ocean, a consequence of ocean acidification, accurate quantitative assessments of Ksp are essential. In addition to the importance of Ksp characterizations in models of oceanic carbon cycling, Ksp parameterizations are essential to assessments of water chemistry in the shellfish industry. Over the past decade, the economic interests of shellfish growers have stimulated research into the effects of Ω on shellfish health. CaCO3 solubility is also important to assessing the economics of certain fisheries. Models of calcium carbonate stability are important to understanding the availability of carbonate-bearing organisms in the surface ocean that serve as an essential food for early-life-stage salmon. Current models of the stability of solid calcium carbonate in seawater are more than thirty-five years old and were generated using measurement techniques that are considered antiquated by modern standards. In this project, Ksp will be determined using modern state-of-the-art procedures for measurements of pH, alkalinity, and carbonate ion concentrations. These measurements will then be used to create quantitative models of Ksp over a wide range of salinities and temperatures.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.

碳酸钙是由经济和环境上重要类型的海洋生物（包括蛤和牡蛎）产生的矿物质（固体），用于结构支持并保护预测。碳酸钙是珊瑚礁的结构性矿物质，由于海洋从大气中吸收了二氧化碳，因此越来越容易受到溶解（化学诱导的分解）的影响。该项目致力于提高预测的准确性和对海洋生态系统非常重要的不同形式碳酸钙稳定性的解释。从（a）测量收集的海水样品中溶解化学成分的浓度以及（b）计算（数学模型）的溶解化学成分的浓度（数学模型），对海水中碳酸钙固体的稳定性或不稳定进行了评估。建模碳酸钙稳定性的必要计算是通过实验产生的，在该实验中，将固体碳酸钙颗粒添加到海水样品中，并允许颗粒溶解直到溶解末端并且此后未观察到颗粒的进一步变化。通过此类实验生产的海水中碳酸钙稳定性的模型对贝类工业很重要，对于理解含碳酸盐生物的天然化学循环非常重要，这些化学循环是作为经济上最重要的海洋生物的食物。在过去的十年中，贝类行业的经济利益刺激了监测工作，以评估孵化场水中碳酸钙稳定性的日常变化。还认识到，碳酸钙稳定性模型对于理解表面海洋中非常小的生物的可用性很重要，这是早期生命阶段鲑鱼的重要食物。海水中碳酸钙稳定性的当前模型已有35年以上，是使用现代标准被认为过时的测量技术生成的。该项目将使用现代最先进的方法来确定碳酸钙在海水中稳定所需的化学条件，然后将使用这些测量值来创建碳酸钙稳定性的定量模型。对于外展活动，科学家计划通过圣彼得堡科学节和女孩海洋学训练营向公众传达研究结果，并为圣彼得堡Scicafe系列介绍有关该项目及其与海洋酸化的关系。这项研究将支持一名学生和一名本科暑期实习生的论文研究。该项目是对碳酸钙（CACO3）的溶解度的最新研究，这是全球海洋中独特的矿物质。陆生CaCO3矿物质的风化以碳酸氢盐（HCO3-）和碳酸盐和碳酸盐[CO3（2-）]的形式增加了碱度。海面的海洋钙化剂沉淀固体CACO3，以进行结构支撑和防止制备。海洋钙化器生产的生物caco3沉降到更深的水域中。这些工艺有时称为碳酸钙泵，对于将碳从地面海洋传递到深度很重要。因此，碳酸钙以其固体形式和溶解成分都起着不可或缺的作用。海洋CACO3溶解度的评估对于对固体CACO3及其溶解成分之间转换的定量理解和解释至关重要。 CACO3的溶解度按照溶解的Ca2+和Co3（2-）浓度（2-）浓度（Mol/kg海水）在海水中的溶解度（KSP）进行定量表达，并在同等的海水中使用CACO3的特定结晶多晶型物。 KSP受海水温度（T），盐度（S）和压力（P）的影响，并用于量化饱和状态（ω），这是海水与溶解的Ca2+和CO3（2-）的水平不足或过饱和的程度。鉴于全球海洋中CACO3的饱和状态的降低，这是海洋酸化的结果，对KSP的准确定量评估至关重要。除了KSP字符在海洋碳循环模型中的重要性外，KSP参数对于评估贝类工业的水化学也至关重要。在过去的十年中，贝类种植者的经济利益激发了对ω对贝类健康的影响的研究。 CACO3溶解度对于评估某些渔业的经济学也很重要。碳酸钙稳定性模型对于理解地表海中碳酸盐生物的可用性很重要，这是早期生命鲑鱼的必要食物。海水中碳酸钙稳定性的当前模型已有35年以上，是使用现代标准被认为过时的测量技术生成的。在该项目中，KSP将使用现代的最先进程序来确定pH，碱度和碳酸盐离子浓度的测量。然后，这些测量将用于在广泛的盐度和温度下创建KSP的定量模型。该奖项反映了NSF的法定任务，并使用基金会的智力优点和更广泛的影响评估标准，被视为通过评估来获得珍贵的支持。