Department of Environmental Engineering Sciences, Engineering School of Sustainable Infrastructure and Environment , University of Florida , Gainesville , Florida 32608 , United States.
Environ Sci Technol. 2018 Jul 3;52(13):7496-7504. doi: 10.1021/acs.est.8b00148. Epub 2018 Jun 15.
The atmospheric process dynamically changes the chemical compositions of organic aerosol (OA), thereby complicating the interpretation of its health effects. In this study, the dynamic evolution of the oxidative potential of various OA was studied, including wood combustion particles and secondary organic aerosols (SOA) generated from different hydrocarbons (i.e., gasoline, toluene, isoprene, and α-pinene). The oxidative potential of OA at different aging stages was subsequently measured by the dithiothreitol consumption (DTT, mass normalized). We hypothesized that DTT consumptions by OA were modulated by catalytic particulate oxidizers (e.g., quinones), noncatalytic particulate oxidizers (e.g., organic hydroperoxides and peroxyacyl nitrates) and electron-deficient alkenes. The results of this study showed that the oxidative potential of OA decreased after an extended period of aging due to the decomposition of particulate oxidizers and electron-deficient alkenes. Quinones (GC-MS data) partially attributed to the DTT of fresh wood smoke particles but rapidly dropped with aging. In biogenic SOA, organic hydroperoxides (4-nitrophenyl boronic acid assay) exclusively accounted for DTT and decreased with aging. The DTT of aromatic SOA, mainly comprising organic hydroperoxides and electron-deficient alkenes (FTIR data), was shortly elevated during the early atmospheric process; however, it showed a noticeable decrease (32-75%) for a long period of aging. We concluded that fresh or moderately aged OA are more reactive to a sulfhydryl group than highly aged OA.
大气过程会动态改变有机气溶胶（OA）的化学成分，从而使人们对其健康影响的解释变得更加复杂。在这项研究中，研究了各种 OA 的氧化势的动态演变，包括木材燃烧颗粒和由不同碳氢化合物（即汽油、甲苯、异戊二烯和α-蒎烯）生成的二次有机气溶胶（SOA）。随后通过二硫苏糖醇消耗（DTT，质量归一化）测量 OA 在不同老化阶段的氧化势。我们假设 OA 的 DTT 消耗受到颗粒氧化剂（例如醌）、非颗粒氧化剂（例如有机过氧化物和过氧酰基硝酸盐）和缺电子烯烃的调节。这项研究的结果表明，由于颗粒氧化剂和缺电子烯烃的分解，OA 的氧化势在长时间老化后会降低。醌（GC-MS 数据）部分归因于新鲜木烟颗粒的 DTT，但随着老化迅速下降。在生物源 SOA 中，有机过氧化物（4-硝基苯硼酸测定）专门用于 DTT，并随着老化而减少。芳香族 SOA 的 DTT 主要由有机过氧化物和缺电子烯烃（FTIR 数据）组成，在大气过程的早期会短暂升高；然而，在长时间老化后，它会显著下降（32-75%）。我们得出结论，新鲜或适度老化的 OA 比高度老化的 OA 对巯基更具反应性。
