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

IF 6.1 2区 环境科学与生态学 Q2 ENGINEERING, ENVIRONMENTAL
Linke Ge, Jinshuai Zheng, Crispin Halsall, Chang-Er Chen, Xuanyan Li, Shengkai Cao, Peng Zhang
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Abstract

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 (λ > 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 ∼ 8–10) were more reactive toward hydroxyl radicals (•OH), while TCs2− (pH ∼ 10) reacted the fastest with singlet oxygen (1O2). 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 1O2 and •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 •OH and 1O2 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.

Abstract Image

可离子化四环素抗生素的水生光转化和光诱导毒性增强
大多数抗生素都含有可离子化的基团,这些基团会发生酸碱解离,从而在水生系统中产生多种解离形式,具体取决于系统的 pH 值。在日照充足的地表水中,光化学转化在决定抗生素归宿方面起着至关重要的作用。本研究全面考察了三种广泛检测到的四环素(TC):四环素(TC)、土霉素(OTC)和金霉素(CTC)的光转化降解动力学、途径和光诱导毒性。在模拟太阳光(λ > 290 nm)下,它们的表观光解遵循伪一阶动力学,速率常数从 H2TCs0 到 TCs2- 显著增加。通过竞争动力学实验和矩阵计算发现,阴离子 HTCs- 或 TCs2-(pH ∼ 8-10)对羟自由基(-OH)的反应性更强,而 TCs2-(pH ∼ 10)与单线态氧(1O2)的反应速度最快。考虑到解离物种,测定了 TCs 的总环境光变半衰期,结果表明其与水的 pH 值和阳光的季节性变化有很大关系。一般来说,表观光解是最主要的光化学过程,其次是 1O2 和 -OH 氧化。根据使用 HPLC-MS/MS 确定的主要光反应产物,确定了这三种反应的不同转化途径。毒性测试和 ECOSAR 软件计算证实,-OH 和 1O2 光氧化过程产生的中间产物比母体化合物毒性更大。这些发现大大提高了我们对水体环境中三氯甲烷复杂的光化学归宿和相关风险的认识。
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来源期刊
Frontiers of Environmental Science & Engineering
Frontiers of Environmental Science & Engineering ENGINEERING, ENVIRONMENTAL-ENVIRONMENTAL SCIENCES
CiteScore
10.90
自引率
12.50%
发文量
988
审稿时长
6.1 months
期刊介绍: Frontiers of Environmental Science & Engineering (FESE) is an international journal for researchers interested in a wide range of environmental disciplines. The journal''s aim is to advance and disseminate knowledge in all main branches of environmental science & engineering. The journal emphasizes papers in developing fields, as well as papers showing the interaction between environmental disciplines and other disciplines. FESE is a bi-monthly journal. Its peer-reviewed contents consist of a broad blend of reviews, research papers, policy analyses, short communications, and opinions. Nonscheduled “special issue” and "hot topic", including a review article followed by a couple of related research articles, are organized to publish novel contributions and breaking results on all aspects of environmental field.
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