Heterogeneous Chemistry of Gas-Phase Intermediates in the OH-oxidation of Dimethyl Sulfide

二甲硫醚 OH 氧化中气相中间体的多相化学

• 批准号: 2304886
• 负责人: Timothy Bertram
• 金额: $ 37.63万
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-01 至 2026-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2304886&HistoricalAwards=false
• 关键词: Heterogeneous; Chemistry; Gas; Phase; Intermediates

With support from the Environmental Chemical Sciences Program of the Division of Chemistry, Professor Timothy Bertram and his students at the University of Wisconsin, Madison are studying sulfur chemistry related to the atmosphere. Volatile organic compounds, emitted from the surface ocean, are oxidized in the earth atmosphere resulting in the formation of low volatility molecules that can nucleate new aerosol particles or condense onto existing aerosol particles. Dimethyl sulfide (DMS) is the most abundant source of reduced sulfur to the marine atmosphere and plays a central role in the formation and growth of aerosol particles in marine environments. Despite the importance of DMS in climate on earth, a comprehensive understanding of the intermediate products in the oxidation of DMS is limited, leading to large variability in estimates of sulfuric acid and methanesulfonic acid (MSA) yields; the key endpoints of DMS oxidation. This project will investigate the heterogeneous kinetics of key intermediates in the oxidation of DMS and how they regulate the production of sulfuric acid and MSA. This project will support the PhD thesis for one chemistry graduate student and multiple undergraduate thesis projects. The research team will continue to be involved the UW Madison chemistry recruitment program (CHOPS, CHemistry OPportunitieS) and the Bridge to the Chemistry Doctorate program designed to support underrepresented students in chemistry. Additionally, the research team will partner with local K-12 schools on the measurement and assessment of indoor air quality in public schools.This project will use laboratory measurements to: 1) quantify the rate of heterogeneous and multiphase reactions of key intermediates in the OH-oxidation of DMS and 2) determine the product yields and chemical mechanism for the condensed phase reaction of hydroperoxymethyl thioformate (HPMTF) in aerosol and cloud water. Specifically, using an entrained aerosol flow reactor coupled to a chemical ionization mass spectrometer, the team will determine the reactive uptake coefficient of dimethyl sulfoxide (DMSO), methanesulfinic acid (MSIA), MSA and HPMTF to representative marine aerosol mimics (e.g., sea spray, ammonium sulfate) as a function of relative humidity and particle acidity. Using a combination of online and offline sampling techniques, the product yields for the condensed phase reactions of HPMTF in cloud water and marine aerosol mimics will be determined. This is expected to permit a more accurate assessment of the fraction of DMS emitted that forms sulfate aerosol.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.

在化学系环境化学科学项目的支持下，威斯康星大学麦迪逊分校的 Timothy Bertram 教授和他的学生正在研究与大气相关的硫化学。从表层海洋排放的挥发性有机化合物在地球大气中被氧化，导致形成低挥发性分子，这些分子可以使新的气溶胶颗粒成核或凝结到现有的气溶胶颗粒上。二甲硫醚 (DMS) 是海洋大气中最丰富的还原硫来源，在海洋环境中气溶胶颗粒的形成和生长中发挥着核心作用。尽管 DMS 对地球气候很重要，但对 DMS 氧化过程中中间产物的全面了解有限，导致硫酸和甲磺酸 (MSA) 产量的估计存在很大差异； DMS 氧化的关键终点。该项目将研究 DMS 氧化过程中关键中间体的非均相动力学以及它们如何调节硫酸和 MSA 的生产。该项目将支持一名化学研究生的博士论文和多个本科论文项目。研究团队将继续参与威斯康星大学麦迪逊分校化学招聘计划（CHOPS、化学机会）和化学博士桥梁计划，旨在支持化学领域代表性不足的学生。此外，研究团队将与当地 K-12 学校合作，对公立学校的室内空气质量进行测量和评估。该项目将利用实验室测量来：1）量化 OH 中关键中间体的异相和多相反应速率-DMS 的氧化和 2) 确定气溶胶和云水中氢过氧甲基硫代甲酸酯 (HPMTF) 的凝聚相反应的产物收率和化学机理。具体来说，使用与化学电离质谱仪耦合的夹带气溶胶流反应器，该团队将确定二甲亚砜 (DMSO)、甲亚磺酸 (MSIA)、MSA 和 HPMTF 对代表性海洋气溶胶模拟物（例如海浪喷雾）的反应吸收系数，硫酸铵）作为相对湿度和颗粒酸度的函数。结合在线和离线采样技术，将确定 HPMTF 在云水和海洋气溶胶模拟物中的凝聚相反应的产物产率。预计这将能够更准确地评估形成硫酸盐气溶胶的 DMS 排放比例。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。