Atmospheric Chemistry of Methylated Selenium Compounds and Physicochemical Properties of the Resulting Aerosols

甲基化硒化合物的大气化学和所得气溶胶的物理化学性质

• 批准号: 2139848
• 负责人: Roya Bahreini
• 金额: $ 66.73万
• 依托单位: University of California-Riverside
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-04-01 至 2025-03-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2139848&HistoricalAwards=false
• 关键词: Atmospheric; Chemistry; Methylated; Selenium; Compounds

This project involves the study of the fate and distribution of atmospheric selenium (Se). An environmental chamber will be used to quantify the formation of secondary organic aerosol from selenium (Se)-containing organic compounds and determine the major gas and aerosol products generated using a suite of online and offline instrumentation. The results obtained from this project will improve the understanding of how long-term exposure to organic Se compounds, especially in areas with Se-rich soils and sediments such as agricultural valleys in the western US, might negatively influence public health.Systematic studies of gas and aqueous phase oxidation of several methylated Se compounds will be conducted under variable nitrogen oxide levels using various oxidants (OH, NO3 and O3) and oxidation time scales. The objectives of this research are to develop an improved understanding of secondary aerosol formation from gas and aqueous phase oxidation of selected methylated Se species and improve knowledge about the chemical and microphysical properties of the resulting aerosols that control the impacts on human health and environmental chemistry. The hypotheses include the following: (1) Photooxidation and nitrate radical oxidation of the selected organoselenium compounds lead to significant secondary aerosol formation and the formation yields are NOx-dependent; The yield of the nitrate oxidation pathway is expected to be like that of photooxidation in the presence of high NOx; (2) Long oxidation times lead to significant fragmentation of the products and, therefore, a reduction in secondary aerosol mass; and (3) Aqueous phase oxidation of methylated Se intermediate oxidation products under low NOx conditions leads to formation of Se-containing secondary aerosol species and a higher concentration of hydroperoxides, which results in the increased production of reactive oxygen species.This effort involves the training and mentoring of several graduate and undergraduate students and includes outreach and educational activities at local high schools and middle schools.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.

该项目涉及大气中硒 (Se) 的归宿和分布研究。环境室将用于量化含硒 (Se) 有机化合物形成的二次有机气溶胶，并使用一套在线和离线仪器确定产生的主要气体和气溶胶产物。该项目获得的结果将提高人们对长期接触有机硒化合物（尤其是在美国西部农业山谷等富含硒土壤和沉积物的地区）可能对公众健康产生负面影响的理解。 气体的系统研究几种甲基化硒化合物的水相氧化将在不同的氮氧化物水平下使用各种氧化剂（OH、NO3和O3）和氧化时间尺度进行。本研究的目的是加深对选定甲基化硒的气相和水相氧化所形成的二次气溶胶的了解，并提高对所产生的气溶胶的化学和微物理特性的了解，以控制对人类健康和环境化学的影响。假设包括以下内容：（1）所选有机硒化合物的光氧化和硝酸根氧化导致显着的二次气溶胶形成，并且形成产率与NOx相关；硝酸盐氧化途径的产率预计与高 NOx 存在下的光氧化产率相似； (2) 氧化时间长导致产物显着破碎，从而减少二次气溶胶质量； (3)在低NOx条件下甲基化Se中间氧化产物的水相氧化导致含Se二次气溶胶物种和较高浓度的氢过氧化物的形成，从而导致活性氧物种的产生增加。这项工作包括训练该奖项反映了 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。