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.

该项目采用了一种新的方法，用于测量使用碳和氧三重同位素的过氧化物和碳酸盐的原位形成，以帮助阐明气溶胶表面的非均相化学转化。臭氧分子在同位素上是独特的，因为它在氧的较重同位素中具有最高的富集度（70-120%），并且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上形成的，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的O-三重同位素测量表明，从臭氧到碳酸盐的异常转移是通过过氧化物进行的。该项目采用夜间和白天的气溶胶采样（12小时采样）的环境空气中的拉霍亚加利福尼亚州，寻找白天/夜间的差异，在13 C和氧三重同位素组成（17 O和18 O）的大气碳酸盐和过氧化氢的粗和细的气溶胶部分。本项目的同位素分析将有助于阐明气溶胶表面非均相反应机制的分子水平细节，这一努力将增进我们对气溶胶辐射特性、氧同位素在冰芯数据中的作用、气溶胶输送对生态系统的影响以及气溶胶对健康的影响的理解。这些结果将解决气溶胶表面薄膜的问题，同时在基础物理化学的重要领域取得进展。