School of Energy and Environment and State Key Laboratory of Marine Pollution, City University of Hong Kong, Hong Kong.
Department of Chemistry and State Key Laboratory of Marine Pollution, City University of Hong Kong, Hong Kong.
J Hazard Mater. 2024 Dec 5;480:136314. doi: 10.1016/j.jhazmat.2024.136314. Epub 2024 Oct 28.
Fluoroquinolones (FQs) are widely prescribed antibiotics that are commonly detected in aquatic environments, but the persistence, fates, and ecotoxicities of new generation FQs have yet to be fully investigated. We investigated the direct and indirect (hydroxyl radical (·OH), singlet oxygen (O21), and excited stated of organic matter (CDOM)) photodegradation of three 3rd generation FQs, moxifloxacin (MOX), gatifloxacin (GAT), and sparfloxacin (SPAR). The photodegradation rates and photolytic quantum yields (Φ) of the FQs depended on their dissociation species at different pH in a range of 1×10 to 1×10 M mol-photon. Unlike MOX and GAT whose zwitterions had the highest Φ, the anionic form of SPAR had the highest Φ. The k values were in the order of: k > k ≈ k with the 10Ms order of magnitude. The k values were in the order of: k (∼10Ms) > k (∼10Ms) > >> k (insignificant). Higher k values were observed for MOX (10 to 10Ms) compared to GAT and SPAR (10 to 10Ms). The zwitterions had the highest reactivities with ·OH and the lowest reactivities with O21 and CDOM. Reactions with ·OH enhanced the formation of transformation products (TPs) from decarboxylation and sidechain oxidation pathways, whereas reactions with O21 and CDOM enhanced the formation of TPs from sidechain oxidation pathways. Some of the TPs were predicted to exhibit aquatic ecotoxicity and environmental persistence. The half-lives of the FQs were estimated to be 0.42 to 0.67 h for MOX and SPAR, and 4.6 to 4.9 h for GAT. Their half-lives and main photochemical fates depended on the surface water pH and water column depth. These results highlight the key roles that photodegradation plays in removing new generation FQs from aquatic environments, though this might lead to the formation of TPs that are harmful to aquatic ecosystems.
氟喹诺酮类（FQs）是广泛使用的抗生素，在水环境中经常被检测到，但新一代 FQs 的持久性、归宿和生态毒性仍有待充分研究。我们研究了三种第三代 FQs（莫西沙星（MOX）、加替沙星（GAT）和司帕沙星（SPAR））的直接和间接（羟基自由基（·OH）、单线态氧（O21）和激发态有机物（CDOM））光降解。在 1×10 到 1×10 M mol-photon 的范围内，FQs 的光降解速率和光解量子产率（Φ）取决于它们在不同 pH 下的离解物种。与 MOX 和 GAT 的两性离子具有最高的 Φ 不同，SPAR 的阴离子形式具有最高的 Φ。k 值的顺序为：k > k ≈ k，数量级为 10Ms。k 值的顺序为：k（10Ms）> k（10Ms）> >> k（不重要）。MOX（10 到 10Ms）的 k 值高于 GAT 和 SPAR（10 到 10Ms）。两性离子与·OH 的反应活性最高，与 O21 和 CDOM 的反应活性最低。与·OH 的反应增强了脱羧和侧链氧化途径转化产物（TPs）的形成，而与 O21 和 CDOM 的反应增强了侧链氧化途径 TPs 的形成。一些 TPs 被预测具有水生生态毒性和环境持久性。MOX 和 SPAR 的半衰期估计为 0.42 到 0.67 h，GAT 的半衰期为 4.6 到 4.9 h。它们的半衰期和主要光化学归宿取决于地表水 pH 和水柱深度。这些结果突出了光降解在从水环境中去除新一代 FQs 方面的关键作用，尽管这可能导致对水生生态系统有害的 TPs 的形成。
