Aquatic photo-transformation and enhanced photoinduced toxicity of ionizable tetracycline antibiotics

作     者：Ge, Linke Zheng, Jinshuai Halsall, Crispin Chen, Chang-Er Li, Xuanyan Cao, Shengkai Zhang, Peng 

作者机构：Shaanxi Univ Sci & Technol Sch Environm Sci & Engn Xian 710021 Peoples R China Univ Lancaster Lancaster Environm Ctr Lancaster LA1 4YQ England South China Normal Univ Environm Res Inst Sch Environm Guangzhou 510006 Peoples R China 

出 版 物：《FRONTIERS OF ENVIRONMENTAL SCIENCE & ENGINEERING》 (Front. Environ. Sci. Eng.)

年 卷 期：2024年第18卷第11期

页      面：139页

核心收录：

学科分类：0830[工学-环境科学与工程（可授工学、理学、农学学位）] 081704[工学-应用化学] 07[理学] 070304[理学-物理化学(含∶化学物理)] 08[工学] 0817[工学-化学工程与技术] 0703[理学-化学] 

基　　金：Key Research and Development Program of Shaanxi Province [2024SF-YBXM-567] National Natural Science Foundation of China [21976045, 22076112] China Scholarship Council (CSC) Scholarship Shaanxi Key Laboratory of Environmental Monitoring and Forewarning of Trace Pollutants [SHJKFJJ202318] 

主　　题：Tetracyclines Dissociation Photodegradation kinetics Reactive oxygen species Transformation products Risks 

摘      要：Most antibiotics contain ionizable groups that undergo acid-base dissociation giving rise to diverse dissociated forms in aquatic systems depending on the pH of the system. In sunlit surface waters, photochemical transformation plays a crucial role in determining the fate of antibiotics. This study presents a comprehensive examination of the photo-transformation degradation kinetics, pathways and photoinduced toxicity of three widely detected tetracyclines (TCs): tetracycline (TC), oxytetracycline (OTC), and chlortetracycline (CTC). Under simulated sunlight (lambda 290 nm), their apparent photolysis followed pseudo-first-order kinetics, with rate constants significantly increasing from H2TCs0 to TCs2-. Through competition kinetic experiments and matrix calculations, it was found that the anions HTCs- or TCs2- (pH similar to 8-10) were more reactive toward hydroxyl radicals (center dot OH), while TCs2- (pH similar to 10) reacted the fastest with singlet oxygen (O-1(2)). Considering the dissociated species, the total environmental photo-transformation half-lives of TCs were determined, revealing a strong dependence on the water pH and seasonal variation in sunlight. Generally, apparent photolysis was the dominant photochemical process, followed by O-1(2) and center dot OH oxidation. Different transformation pathways for the three reactions were determined based on the key photoproducts identified using HPLC-MS/MS. Toxicity tests and ECOSAR software calculations confirmed that the intermediates produced by the center dot OH and O-1(2) photo-oxidation processes were more toxic than the parent compounds. These findings significantly enhance our understanding of the complex photochemical fate and associated risks of TCs in aqueous environments.