Aerosol-bound organic radicals,including environmentally persistent free radicals(EPFRs),are key components that affect climate,air quality,and human health.While putative structures have been proposed,the molecular c...Aerosol-bound organic radicals,including environmentally persistent free radicals(EPFRs),are key components that affect climate,air quality,and human health.While putative structures have been proposed,the molecular characteristics of EPFRs remain unknown.Here,we report a surrogate method to characterize EPFRs in real ambient samples using mass spectrometry.The method identifies chemically relevant oxygenated polycyclic aromatic hydrocarbons(OxPAH)that interconvert with oxygen-centered EPFR(OC-EPFR).We found OxPAH compounds most relevant to OC-EPFRs are structurally rich and diverse quinones,whose diversity is strongly associated with OC-EPFR levels.Both atmospheric oxidation and combustion contributed to OC-EPFR formation.Redundancy analysis and photochemical aging model show pyrolytic sources generated more oxidized OC-EPFRs than photolytic sources.Our study reveals the detailed molecular characteristics of OC-EPFRs and shows that oxidation states can be used to identify the origins of OC-EPFRs,offering a way to track the development and evolution of aerosol particles in the environment.展开更多
基金supported by the National Natural Science Foundation of China(92143301 and 91843301)the National Key Research and Development Program of China(2020YFF01014504)the Chinese Academy Sciences Youth Innovation Promotion Association projects。
文摘Aerosol-bound organic radicals,including environmentally persistent free radicals(EPFRs),are key components that affect climate,air quality,and human health.While putative structures have been proposed,the molecular characteristics of EPFRs remain unknown.Here,we report a surrogate method to characterize EPFRs in real ambient samples using mass spectrometry.The method identifies chemically relevant oxygenated polycyclic aromatic hydrocarbons(OxPAH)that interconvert with oxygen-centered EPFR(OC-EPFR).We found OxPAH compounds most relevant to OC-EPFRs are structurally rich and diverse quinones,whose diversity is strongly associated with OC-EPFR levels.Both atmospheric oxidation and combustion contributed to OC-EPFR formation.Redundancy analysis and photochemical aging model show pyrolytic sources generated more oxidized OC-EPFRs than photolytic sources.Our study reveals the detailed molecular characteristics of OC-EPFRs and shows that oxidation states can be used to identify the origins of OC-EPFRs,offering a way to track the development and evolution of aerosol particles in the environment.
