Dissolved black carbon (DBC) can generate reactive oxygen species (ROS), playing significant roles in contaminants degradation and chemical stresses to microorganisms. However, little is known regarding the photoproduction sites to ROS generation, mainly because of its extremely complicated composition. Herein, the ROS generation and photoexcited alteration of DBC were investigated. The generation mechanisms of hydroxyl radical (•OH), superoxide anion (O), and singlet oxygen (O) were inferred by employing various model chemicals. Results showed that the photo-excited aliphatic carbonyls greatly contributed to ∙OH, O, and O generation. Ether groups were identified as the main structural source of HO-dependent ∙OH generation. The novel non-electron transfer process involved carbonyl, ether, alcohol, and ester groups to produce O was proposed. These findings reveal the vital role of oxygenated functional groups within DBC in the photoactive generation of ROS, and thus provides new theoretical information for DBC’s environmental geochemical behavior.

中文翻译：

---

识别溶解黑碳中活性氧的光产生位点：含氧官能团的显着作用

溶解的黑碳（DBC）可以产生活性氧（ROS），在污染物降解和微生物化学应激中发挥重要作用。然而，人们对ROS产生的光产生位点知之甚少，主要是因为其组成极其复杂。在此，研究了 ROS 的产生和 DBC 的光激发改变。通过使用各种模型化学品推断了羟基自由基（·OH）、超氧阴离子（O）和单线态氧（O）的生成机制。结果表明，光激发的脂肪族羰基极大地促进了∙OH、O和O的生成。醚基团被确定为 H2O 依赖性 ∙OH 生成的主要结构来源。提出了涉及羰基、醚、醇和酯基团产生 O 的新型非电子转移过程。这些发现揭示了DBC中含氧官能团在ROS光活性生成中的重要作用，从而为DBC的环境地球化学行为提供了新的理论信息。