The Role of Photo-Generated Hydrated Electrons in Determining the Environmental Fate of Short-Chain Chlorinated Paraffins in Surface Waters

光生水合电子在确定地表水中短链氯化石蜡的环境归宿中的作用

• 批准号: 1808054
• 负责人: Christoph Aeppli
• 金额: $ 39.96万
• 依托单位: Bigelow Laboratory for Ocean Sciences
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-08-15 至 2022-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1808054&HistoricalAwards=false
• 关键词: Role; Photo; Generated; Hydrated; Electrons

This award from the Environmental Chemical Sciences Program in the Division of Chemistry supports Dr. Christoph Aeppli at Bigelow Laboratory for Ocean Sciences. The goal of this project is to study how sunlight determines the fate of short-chain chlorinated paraffins (SCCPs) in surface water of lakes and oceans. These compounds have been classified as persistent organic pollutants, but there are insufficient scientific data to assess their fate in the aqueous phase. Specifically, there are knowledge gaps about a process called indirect photolysis of SCCPs. In this project, this process is studied in the laboratory under environmentally relevant conditions. The degradation of SCCPs is mediated by two primary species responsible for indirect photolysis: the so-called hydrated electron and the hydroxyl radical. The mechanisms and rates of these reactions are being determined. There are indications that the pathway mediated by hydrated electrons is highly effective for degrading hydrophobic pollutants, especially in surface water. In such systems, the presence of dissolved organic matter is expected to facilitate the transformation reaction. The anticipated outcome of this research is a better understanding of the loss and persistence of an important class of pollutants in lakes and oceans. Undergraduate students from Colby college participate in this research both in the summer and during the academic year. They gain intense hands-on research experience in laboratory environmental chemistry. A postdoctoral researcher learns about the intersection of photochemistry, high-end analytical techniques, and computational chemistry. This project investigates whether hydrated electrons are the active species for the photolysis of SCCPs in surface water. It is hypothesized that this photochemical degradation with hydrated electrons occurs in dissolved organic matter (DOM) aggregates. Irradiation experiments are conducted using DOM-containing systems as well as clean systems that allow a separate investigation of the SCCP photolysis by hydrated electrons as well as by hydroxyl radicals. Comprehensive two-dimensional gas chromatography is used to quantify degradation of the highly complex mixture of SCCP congeners. To interpret results from the DOM-containing photolysis experiments, the affinity of individual SCCP congeners into the DOM phase is being estimated using quantum chemical-based computational chemistry tools. Overall, this project advances the understanding of the photochemical fate of hydrophobic pollutants in surface waters. The project also improves the fundamental knowledge of a so-far understudied photoreactive species, the hydrated electron. Furthermore, this project trains the next generation of researchers and includes a significant undergraduate education component. Additionally, there is an active outreach program to educate the broader community on the relevance of the research.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.

化学部环境化学科学计划的这一奖项支持毕格罗海洋科学实验室的Christoph Aeppli博士。该项目的目标是研究阳光如何决定湖泊和海洋地表水中短链氯化石蜡（SCCP）的命运。这些化合物已被列为持久性有机污染物，但没有足够的科学数据来评估其在水相中的归宿。具体而言，在短链氯化石蜡的间接光解过程方面存在知识空白。在该项目中，在实验室中在环境相关条件下对这一过程进行了研究。短链氯化石蜡的降解由两种主要的间接光解物质介导：所谓的水合电子和羟基自由基。这些反应的机制和速率正在确定中。有迹象表明，由水合电子介导的途径对于降解疏水性污染物是非常有效的，特别是在地表水中。在这样的系统中，溶解的有机物的存在预计将促进转化反应。这项研究的预期成果是更好地了解湖泊和海洋中一类重要污染物的损失和持久性。科尔比学院的本科生在夏季和学年期间都参加这项研究。他们在实验室环境化学方面获得了丰富的实践研究经验。博士后研究人员了解光化学，高端分析技术和计算化学的交叉点。该项目调查水合电子是否是地表水中短链氯化石蜡光解的活性物质。据推测，这种水合电子的光化学降解发生在溶解有机物（DOM）聚集体中。辐照实验是使用含有DOM的系统和清洁系统进行的，这些系统允许对短链氯化石蜡通过水合电子和羟基自由基的光解进行单独研究。全面的二维气相色谱法被用来量化高度复杂的短链氯化石蜡同系物混合物的降解情况。为了解释含DOM的光解实验的结果，正在使用基于量子化学的计算化学工具来估算单个短链氯化石蜡同系物进入DOM阶段的亲和力。总的来说，该项目促进了对表面沃茨中疏水污染物的光化学命运的理解。该项目还提高了迄今为止研究不足的光反应物质水合电子的基础知识，此外，该项目还培训了下一代研究人员，并包括一个重要的本科教育组成部分。此外，还有一个积极的外展计划，教育更广泛的社区对研究的相关性。这个奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估的支持。

项目成果

Photochemical degradation of short-chain chlorinated paraffins in aqueous solution by hydrated electrons and hydroxyl radicals

• DOI: 10.1016/j.chemosphere.2022.134732
• 发表时间: 2022-05-17
• 期刊: CHEMOSPHERE
• 影响因子: 8.8
• 作者: DiMento, Brian P.;Tusei, Cristina L.;Aeppli, Christoph
• 通讯作者: Aeppli, Christoph