Superoxide Formation from Aqueous Reactions of Biogenic Secondary Organic Aerosols
Superoxide Formation from Aqueous Reactions of Biogenic Secondary Organic Aerosols
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生物二次有机气溶胶的水反应形成超氧化物
DOI：
10.1021/acs.est.0c07789
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发表时间：
2021
影响因子：
11.4
通讯作者：
Shiraiwa, Manabu
中科院分区：
文献类型：
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作者：
Wei, Jinlai;Fang, Ting;Wong, Cynthia;Lakey, Pascale S.;Nizkorodov, Sergey A.;Shiraiwa, Manabu
活性氧（ROS）在大气气溶胶的水相过程和健康效应中起着重要作用。虽然羟基自由基（·OH）和过氧化氢（H2 O2）被认为是与二次有机气溶胶（SOA）相关的主要氧化剂，但超氧阴离子（O2·-）形成的动力学和反应机制很少被量化，并且了解得很少。在这里，我们证明了O2·-的形成占主导地位的摩尔产率为0.01-0.03%，从生物SOA的水反应产生的异戊二烯，β-蒎烯，α-松油醇，和d-柠檬烯·OH光氧化。·OH和O2·-形成的时间演变是通过级联水反应的动力学模型来阐明的，包括有机氢过氧化物的分解、伯醇或仲醇的·OH氧化以及α-羟基过氧自由基的单分子分解。各种类型的ROS的相对产率反映了SOA中所含的有机氢过氧化物和醇的相对丰度。这些研究结果和机制的理解有重要的影响，大气命运的SOA和颗粒相反应的高度氧化的有机分子，以及呼吸沉积后的氧化应激。
Reactive oxygen species (ROS) play a central role in aqueous-phase processing and health effects of atmospheric aerosols. Although hydroxyl radical (•OH) and hydrogen peroxide (H2O2) are regarded as major oxidants associated with secondary organic aerosols (SOA), the kinetics and reaction mechanisms of superoxide (O2•–) formation are rarely quantified and poorly understood. Here, we demonstrate a dominant formation of O2•–with molar yields of 0.01–0.03% from aqueous reactions of biogenic SOA generated by•OH photooxidation of isoprene, β-pinene, α-terpineol, andd-limonene. The temporal evolution of•OH and O2•–formation is elucidated by kinetic modeling with a cascade of aqueous reactions including the decomposition of organic hydroperoxides,•OH oxidation of primary or secondary alcohols, and unimolecular decomposition of α-hydroxyperoxyl radicals. Relative yields of various types of ROS reflect a relative abundance of organic hydroperoxides and alcohols contained in SOA. These findings and mechanistic understanding have important implications on the atmospheric fate of SOA and particle-phase reactions of highly oxygenated organic molecules as well as oxidative stress upon respiratory deposition.