Laboratory of Basin Hydrology and Wetland Eco-restoration, School of Environmental Studies, China University of Geosciences (Wuhan), Wuhan, 430074, People's Republic of China.
Engineering Research Center of Nano-Geo Materials of Ministry of Education, China University of Geosciences (Wuhan), Wuhan, 430074, People's Republic of China.
Environ Sci Pollut Res Int. 2018 Dec;25(36):36368-36380. doi: 10.1007/s11356-018-3499-4. Epub 2018 Oct 27.
Rainfall is a highly effective and important carrier that can remove a majority of aerosol mass into land and marine ecosystems. The photochemically formed reactive species in the rainwater are likely dominant oxidants for organic and inorganic substances. Here, we collected rainwater samples from Oct. 2016 to Dec. 2016 in CUG campus (Wuhan, Hubei, China) and measured their formation rates, lifetimes, steady-state concentrations, and apparent quantum yields of reactive photoinduced species, including hydroxyl radical (HO•), HO, singlet oxygen (O), and chromophoric dissolved organic matter triplet state (CDOM*) in the laboratory. Results showed that rainwater samples contained photochemical sources, like DOM, nitrate, heavy metals, etc. Quantification of HO• showed that r (the photogeneration rate of HO•) were in the range of 1.05 × 10-4.56 × 10 M s, and [•OH]ss (the steady-state concentrations of OH•) were of 4.06 × 10-2.97 × 10 M for the three samples. Further investigations revealed that 10-24% of r was attributed to nitrate photolysis, suggesting DOM was possibly the prevailing source of HO•. Apparent quantum yields of HO (Φ) correlated negatively with E/E (the ratio of absorption at 250 and 365 nm), while Φ and Φ increased with elevated E/E.
降雨是一种非常有效且重要的载体，可以将大部分气溶胶物质转移到陆地和海洋生态系统中。雨水中光化学形成的活性物质很可能是有机和无机物质的主要氧化剂。在这里，我们收集了 2016 年 10 月至 2016 年 12 月期间在 CUG 校园（中国湖北武汉）的雨水样本，并在实验室中测量了它们的生成速率、寿命、稳态浓度和活性光诱导物种（包括羟基自由基 (HO•)、HO、单线态氧 (O) 和发色溶解有机物质三重态 (CDOM*)）的表观量子产率。结果表明，雨水样本中含有 DOM、硝酸盐、重金属等光化学来源。HO•的定量分析表明，r（HO•的光生成速率）在 1.05×10-4.56×10 M s 的范围内，而[•OH]ss（OH•的稳态浓度）在三个样本中分别为 4.06×10-2.97×10 M。进一步的研究表明，r 的 10-24%归因于硝酸盐光解，这表明 DOM 可能是 HO•的主要来源。HO 的表观量子产率（Φ）与 E/E（250nm 和 365nm 处吸收的比值）呈负相关，而Φ和Φ随着 E/E 的升高而增加。
