Arsenic Complexation with Reduced Organosulfur Moieties in Soil Organic Matter: Implications for Arsenic Oxidation via Biotic and Abiotic Pathways

土壤有机质中砷与减少的有机硫部分的络合：对生物和非生物途径砷氧化的影响

基本信息

批准号：
1905175
负责人：
Matthew Reid
金额：
$ 35.51万
依托单位：
Cornell University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2019
资助国家：
美国
起止时间：
2019-09-01 至 2024-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1905175&HistoricalAwards=false
关键词：
Arsenic Complexation Reduced Organosulfur Moieties

项目摘要

Supported by the Environmental Chemical Sciences Program in the Division of Chemistry, Professor Matthew Reid and his students are studying interactions between inorganic arsenic and dissolved organic matter (DOM). DOM is a complex mixture of biomolecules derived from plant residues and microorganisms, and is an important component of all natural environments. DOM binds arsenic to form dissolved complexes with significantly different properties than unbound inorganic arsenic molecules. These reactions influence arsenic concentration in water and uptake into plants, with important implications for human exposure to arsenic, a human carcinogen. However, the functional groups of DOM that react with arsenic are poorly understood. In this project, researchers explore how the structure of DOM affects its reactivity with arsenic, and evaluate how arsenic-DOM binding influences arsenic behavior in soils. Throughout this research, undergraduate and graduate students are trained in experimental methods and characterization techniques to address fundamental problems in environmental chemistry. A graduate student is partnering with outreach staff from the Cayuga Nature Center to develop hands-on activities with a portable X-ray fluorescence instrument. This outreach strengthens the student's science communication skills and engages high school teachers and the public with soil chemistry topics of societal importance. In this project, standard humic substances as well as hydrophobic and hydrophilic DOM fractions isolated from wetland soils with a range of sulfur concentrations are reacted with arsenite (As(III)) in order to explore As(III)-DOM coordination reactions. In the first phase of the research, wet chemical analysis and synchrotron-based XAS are integrated with laboratory dialysis equilibrium experiments to quantify conditional distribution coefficients, characterize sulfur speciation in DOM, and determine the As coordination environment in DOM-bound As. In the second phase of the research, impacts of As(III) binding by DOM on As(III) oxidation kinetics via abiotic and microbial pathways are evaluated using laboratory batch studies. These research activities are designed to test the hypothesis that thiol functional moieties are high-affinity binding sites for As(III), and that As(III) bound with thiol functionalities in DOM will be stabilized in its trivalent oxidation state during oxidizing conditions. Research outcomes are expected to improve geochemical modeling of As speciation in DOM-rich environments and provide new insight into arsenic oxidation reactions in redox dynamic environments.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.

在化学部的环境化学科学计划的支持下，马修·里德（Matthew Reid）教授和他的学生正在研究无机砷和溶解有机物（DOM）之间的相互作用。 DOM是源自植物残基和微生物的生物分子的复杂混合物，并且是所有自然环境的重要组成部分。 DOM结合砷，形成与未结合的无机砷分子具有明显不同特性的溶解复合物。这些反应会影响水中的砷浓度，并吸收植物，这对人类致癌物砷的暴露具有重要意义。但是，与砷反应的DOM的官能团对此知之甚少。在该项目中，研究人员探讨了DOM的结构如何影响其与砷的反应性，并评估砷 - 育约合的结合如何影响土壤中的砷行为。在整个研究中，对本科生和研究生进行了实验方法和表征技术的培训，以解决环境化学的基本问题。一名研究生正在与Cayuga Nature Center的外展人员合作，使用便携式X射线荧光仪器开发动手活动。这种宣传增强了学生的科学沟通技巧，并通过社会重要性的土壤化学主题吸引了高中教师和公众。在这个项目中，从湿地土壤中分离出具有一系列硫浓度的疏水性和亲水性DOM馏分，与砷矿（AS（iii））反应，以探索AS（III） - 协调反应。在研究的第一阶段中，湿化学分析和基于同步加速器的XAS与实验室透析平衡实验集成在一起，以量化条件分布系数，表征DOM中的硫形成性，并确定DOM-BON-BOND AS中的AS协调环境。在研究的第二阶段中，使用实验室批次研究评估了DOM对AS（III）对AS（III）氧化动力学的影响。这些研究活动旨在检验以下假设：硫醇功能部分是AS（iii）的高亲和力结合位点，并且在DOM中与硫醇功能结合的AS（III）将在其在氧化条件下以其三价氧化状态稳定。预计研究结果将改善DOM-RICH环境中AS形成的地球化学建模，并为氧化还原动态环境中的砷氧化反应提供新的见解。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子优点和更广泛的影响审查标准来通过评估来支持的。