NSFGEO-NERC: A Thermodynamic Chemical Speciation Model for the Oceans, Seas, and Estuaries

NSFGEO-NERC：海洋和河口的热力学化学形态模型

• 批准号: NE/P012361/1
• 负责人: Simon Clegg
• 金额: $ 46.9万
• 依托单位: University of East Anglia
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2017
• 资助国家: 英国
• 起止时间: 2017 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FP012361%2F1
• 关键词: NSFGEO; NERC; Thermodynamic; Chemical; Speciation

Ocean acidification due to the dissolution of anthropogenic CO2, and the effects of cumulative stressors (including acidification, pollution, warming, and anoxia) are among the top priorities for ocean research, requiring accurate and consistent measurements across the globe to monitor and understand present effects, and modelling to evaluate future scenarios and methods of remediation. The work of observational scientists and modellers is linked by the need for an accurate knowledge of the chemical speciation of the inorganic carbonate system, pH, and nutrient and contaminate trace metals, in both natural waters and the reference materials and solutions used for instrument calibration.Chemical speciation is defined as the distribution of a chemical element between different molecular and ionic forms in seawater, and determines its reactivity and bioavailability. Speciation depends on the value of the relevant thermodynamic equilibrium constant, and on the activities of each of the dissolved ions and molecules. These are complex functions of temperature, pressure, and salinity (or, more generally, solution composition), and cannot be predicted from theory. Many of the important reactions in seawater involve acid-base equilibria, which introduces pH as an additional variable. Despite the importance of chemical speciation, the available calculation tools are often only simple empirical equations that yield equilibrium constants for reactions as functions of salinity and temperature. Such equations cannot be used for many important natural waters whose composition differs from that of normal seawater (e.g., polar brines, estuaries, pore-waters, enclosed seas, and paleo-oceans). Furthermore, human-driven changes in seawater pH and carbonate chemistry in shelf seas and estuaries are complicated by the effects of eutrophication, upwelling, the dissolved solutes contained in river water, and changes in metal toxicity accompanying pH change. Consequently, despite the best efforts of physical chemists over the last several decades, there is not yet the ability to calculate the equilibria controlling the chemical factors impacting shellfish and a broader range of marine fauna in the brackish/mesohaline environments typical of many estuaries and coasts.We will create a step change in the capability of marine scientists to measure, interpret, and predict chemical speciation and pH in natural waters of varying composition by creating a speciation model based upon the Pitzer equations for the calculation of solute and water activities. The approach has a long track record of success in geochemistry. The equations are based upon the concept that interactions between pairs and triplets of dissolved solute species control activities. The values of the parameters for these interactions are determined from a wide range of measurements of solution properties. Work in this project will include measuring activities and heat capacities, and using recent literature data, to improve and test the model; the computer coding and validation of the model and the development of methods to quantify the relationship between uncertainties in model-predicted speciation and those in the underlying measurements; and engagement with oceanographers internationally to help design practical speciation modelling tools and associated guidance for specific applications. The completed model will enable the activities and speciation of all seawater components to be calculated within a unified framework that, (i) includes the major and trace elements in seawater and its mixtures with freshwaters, (ii) includes other saline environments of differing composition, and (iii) encompasses the buffers that are used to calibrate pH and other instruments, and. Our results will this advance the quantitative understanding of chemical speciation - from ocean measurements to ecosystem models - for an expanded range of natural water bodies and marine environments.

由于人为CO2溶解造成的海洋酸化以及累积压力源（包括酸化、污染、变暖和缺氧）的影响是海洋研究的首要任务，需要在全球范围内进行准确和一致的测量，以监测和了解当前的影响，并建立模型以评估未来的情景和补救方法。观测科学家和建模人员的工作与需要准确了解天然水体和用于仪器校准的参考物质和溶液中无机碳酸盐系统的化学形态、pH值和营养物质和污染微量金属的需求有关。化学形态被定义为一种化学元素在海水中不同分子和离子形态之间的分布，并决定其反应性和生物利用度。物种形成取决于相关的热力学平衡常数的值，以及每一个溶解的离子和分子的活性。这些是温度、压力和盐度（或者更一般地说，溶液组成）的复杂函数，不能从理论上预测。海水中的许多重要反应都涉及酸碱平衡，这就引入了pH值作为附加变量。尽管化学形态的重要性，可用的计算工具往往只是简单的经验方程，得出反应的平衡常数作为盐度和温度的函数。这种方程不能用于许多组成不同于正常海水的重要天然水（如极地盐水、河口、孔隙水、封闭海和古海洋）。此外，由于富营养化、上升流、河水中溶解溶质的影响以及pH变化带来的金属毒性的变化，使得陆架海和河口的海水pH和碳酸盐化学的人为变化变得复杂。因此，尽管在过去的几十年里物理化学家尽了最大的努力，但在许多河口和海岸典型的半咸水/中盐环境中，仍然没有能力计算控制影响贝类和更广泛的海洋动物的化学因素的平衡。我们将创建一个基于计算溶质和水活动的Pitzer方程的物种形成模型，从而使海洋科学家在测量、解释和预测不同组成的自然水中的化学物种形成和pH值的能力发生一步变化。这种方法在地球化学领域有着长期的成功记录。这些方程是基于溶质对和三组溶质之间的相互作用控制活性的概念。这些相互作用的参数值是根据对溶液性质的广泛测量确定的。该项目的工作将包括测量活动和热容，并使用最近的文献数据来改进和测试模型；模型的计算机编码和验证，以及开发量化模型预测的物种形成的不确定性与基础测量的不确定性之间关系的方法；并与国际海洋学家合作，帮助设计实用的物种建模工具和相关的具体应用指南。完成后的模型将能够在一个统一的框架内计算所有海水成分的活动和形态，该框架包括：(i)包括海水及其与淡水的混合物中的主要和微量元素，（ii）包括其他不同成分的盐环境，以及（iii）包括用于校准pH值和其他仪器的缓冲液，以及。我们的研究结果将促进对化学物种形成的定量理解——从海洋测量到生态系统模型——用于扩大自然水体和海洋环境的范围。

项目成果

Modelling seawater carbonate chemistry in shellfish aquaculture regions: Insights into CO2 release associated with shell formation and growth

• DOI: 10.1016/j.aquaculture.2018.11.028
• 发表时间: 2019-02
• 期刊: Aquaculture
• 影响因子: 4.5
• 作者: J. Morris;M. Humphreys

Solid–Liquid Equilibria in Aqueous Solutions of Tris, Tris-NaCl, Tris-TrisHCl, and Tris-(TrisH) 2 SO 4 at Temperatures from 5 to 45 °C

5 至 45 °C 温度下 Tris、Tris-NaCl、Tris-TrisHCl 和 Tris-(TrisH) 2 SO 4 水溶液中的固液平衡

• DOI: 10.1021/acs.jced.0c00744
• 发表时间: 2021
• 期刊: Journal of Chemical & Engineering Data
• 作者: Lodeiro, Pablo;Turner, David R.;Achterberg, Eric P.;Gregson, Florence K.;Reid, Jonathan P.;Clegg, Simon L.
• 通讯作者: Clegg, Simon L.

Chemical speciation models based upon the Pitzer activity coefficient equations, including the propagation of uncertainties. II. Tris buffers in artificial seawater at 25 °C, and an assessment of the seawater ‘Total’ pH scale

基于 Pitzer 活度系数方程的化学形态模型，包括不确定性的传播。

• DOI: 10.1016/j.marchem.2022.104096
• 发表时间: 2022
• 期刊: Marine Chemistry
• 影响因子: 3
• 作者: Clegg, Simon L.;Humphreys, Matthew P.;Waters, Jason F.;Turner, David R.;Dickson, Andrew G.
• 通讯作者: Dickson, Andrew G.

Chemical speciation models based upon the Pitzer activity coefficient equations, including the propagation of uncertainties. III. Seawater from the freezing point to 45 °C, including acid-base equilibria

基于 Pitzer 活度系数方程的化学形态模型，包括不确定性的传播。

• DOI: 10.1016/j.marchem.2022.104196
• 发表时间: 2023
• 期刊: Marine Chemistry
• 影响因子: 3
• 作者: Clegg S

Chemical speciation models based upon the Pitzer activity coefficient equations, including the propagation of uncertainties: Artificial seawater from 0 to 45 °C

基于 Pitzer 活度系数方程的化学形态模型，包括不确定性的传播：0 至 45°C 的人造海水

• DOI: 10.1016/j.marchem.2022.104095
• 发表时间: 2022
• 期刊: Marine Chemistry
• 影响因子: 3
• 作者: Humphreys, Matthew P.;Waters, Jason F.;Turner, David R.;Dickson, Andrew G.;Clegg, Simon L.
• 通讯作者: Clegg, Simon L.