Heterogeneous and Photochemical Transformations on Aerosol Surfaces: Understanding the Link between Hydrogen Peroxide and Carbonates Using Carbon and Oxygen Triple Isotopes

气溶胶表面的异质和光化学转化：利用碳和氧三重同位素了解过氧化氢和碳酸盐之间的联系

• 批准号: 1259305
• 负责人: Mark Thiemens
• 金额: $ 43.73万
• 依托单位: University of California-San Diego
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-01 至 2017-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1259305&HistoricalAwards=false
• 关键词: Heterogeneous; Photochemical; Transformations; Aerosol; Surfaces

This project incorporates a novel approach for measuring in-situ formation of peroxide and carbonates using carbon and oxygen triple isotopes to help elucidate heterogeneous chemical transformations on aerosol surfaces. The ozone molecule is unique isotopically as it possesses the highest enrichment (70-120%) in the heavier isotopes of oxygen and serves as a natural tracer of chemical reactions involving ozone interaction. Since hydrogen peroxide is formed on aerosol surfaces, O-triple isotopic measurements of the newly formed peroxide on aerosol surfaces in the laboratory with ozone, water, and CaO indicate that the transfer of anomaly from ozone to carbonates proceeds via peroxide. This project employs both night and daytime aerosol sampling (12h sampling) of ambient air in La Jolla CA to look for day/night differences in 13C and oxygen triple isotopic composition (17O and 18O) of atmospheric carbonates and hydrogen peroxide in coarse and fine fractions of aerosols. The isotopic analyses in this project will help elucidate the molecular-level details of the mechanisms of heterogeneous reactions at aerosol surfaces.This effort will enhance our understanding of the radiative properties of aerosols, the role of oxygen isotopes in ice core data, impacts of aerosol transport to ecosystems, and health impacts of aerosols. The results will address the issue of thin films on aerosol surfaces while at the same time make progress in areas of importance to fundamental physical chemistry.

该项目采用了一种使用碳和氧三重同位素测量过氧化物和碳酸盐原位形成的新方法，以帮助阐明气溶胶表面的异质化学转化。臭氧分子具有独特的同位素，因为它在氧的较重同位素中具有最高的富集度（70-120%），并且可以作为涉及臭氧相互作用的化学反应的天然示踪剂。由于过氧化氢是在气溶胶表面形成的，在实验室中用臭氧、水和 CaO 对气溶胶表面上新形成的过氧化物进行 O 三重同位素测量表明，异常从臭氧到碳酸盐的转移是通过过氧化物进行的。该项目对加利福尼亚州拉荷亚的环境空气进行夜间和白天气溶胶采样（12 小时采样），以寻找气溶胶粗粒和细粒部分中大气碳酸盐和过氧化氢的 13C 和氧三重同位素组成（17O 和 18O）的昼夜差异。该项目中的同位素分析将有助于阐明气溶胶表面异质反应机制的分子水平细节。这项工作将增强我们对气溶胶的辐射特性、氧同位素在冰芯数据中的作用、气溶胶传输对生态系统的影响以及气溶胶对健康的影响的理解。研究结果将解决气溶胶表面的薄膜问题，同时在基础物理化学的重要领域取得进展。