文献类型：期刊文献

英文题名：Aqueous photodegradation of the benzophenone fungicide metrafenone: Carbon-bromine bond cleavage mechanism

作者：Hong, Minghui[1];Yang, Xuerui[1];Zhang, Xuewei[1];Ji, Yuefei[2];Zhou, Lei[1];Xiu, Guangli[1];Ni, Zhigang[3];Richard, Claire[4]

机构：[1]East China Univ Sci & Technol, Sch Resources & Environm Engn, State Environm Protect Key Lab Environm Risk Asse, Shanghai 200237, Peoples R China;[2]Nanjing Agr Univ, Coll Resources & Environm Sci, Nanjing 210095, Peoples R China;[3]Hangzhou Normal Univ, Coll Mat Chem & Chem Engn, Hangzhou 311121, Peoples R China;[4]Univ Clermont Auvergne, CNRS, Inst Chim Clermont Ferrand, Sigma Clermont, F-63178 Aubiere, France

年份：2021

卷号：206

外文期刊名：WATER RESEARCH

收录：;EI(收录号：20214311078204);WOS:【SCI-EXPANDED(收录号:WOS:000713293000010)】；

语种：英文

外文关键词：Metrafenone; Photolysis; Debromination; Homolytic cleavage; Bond dissociation energy

摘要：Metrafenone (MF), as a new type of benzophenone fungicide, has been widely used in agriculture and is persistent in the environment. Understanding its photochemical fate is essential for the comprehensive evaluation of its ecological risk. In the present work, we reported a detailed study on the photochemical transformation of MF in aqueous solution under irradiation (at lambda > 290 nm using a high pressure mercury lamp). MF was relatively photo-reactive showing a low polychromatic quantum yield of photolysis (1.06 x 10(-4), 20 mu M) counterbalanced by a significant light absorption above 290 nm. A series of photoproducts were identified by high resolution mass spectrometry (HR-MS) analysis, and three different pathways, including oxidation of the methyl group, debromination and replacement of bromine by hydroxyl group were proposed. Among them, debromination was identified as the dominating process that could be achieved via homolytic C-Br bond cleavage from singlet and triplet MF, as confirmed by laser flash photolysis (LFP) experiments and density functional theory (DFT) calculations. Toxicity assessment revealed that photochemical degradation reduced the ecotoxicity of MF efficiently. Nitrate ions and humic acid promoted the MF photolysis, while bicarbonate exhibited no effect. Results obtained in this work would increase our understanding on the environmental fate of MF in sunlit surface waters.