CAS Key Laboratory of Urban Pollutant Conversion, Fujian Key Laboratory of Watershed Ecology, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China.
University of Chinese Academy of Sciences, Beijing 100043, China.
Environ Sci Technol. 2024 Jul 2;58(26):11661-11674. doi: 10.1021/acs.est.4c01141. Epub 2024 Jun 14.
This study addresses existing gaps in understanding the specific involvement of dissolved organic matter (DOM) fractions in antibiotic photolysis, particularly under natural conditions and during DOM photobleaching. Employing fluorescent, chemical, and molecular analysis techniques, it explores the impact of extracellular and intracellular organic matter (EOM and IOM) on the photodissipation of multiclass antibiotics, coupled with DOM photobleaching under natural solar radiation. Key findings underscore the selective photobleaching of DOM fractions, propelled by distinct chemical profiles, influencing DOM-mediated antibiotic photolysis. Notably, lipid-like substances dominate in the IOM, while lignin-like substances prevail in the EOM, each uniquely responding to sunlight and exhibiting selective photobleaching. Sunlight primarily targets fulvic acid-like lignin components in EOM, contrasting the initial changes observed in tryptophan-like lipid substances in IOM. The lower photolability of EOM, attributed to its rich unsaturated compounds, contributes to an enhanced rate of indirect antibiotic photolysis (0.339-1.402 h) through reactive intermediates. Conversely, the abundance of aliphatic compounds in IOM, despite it being highly photolabile, exhibits a lower mediation of antibiotic photolysis (0.067-1.111 h). The triplet state excited DOM* plays a pivotal role in the phototransformation and toxicity decrease of antibiotics, highlighting microbial EOM's essential role as a natural aquatic photosensitizer for water self-purification. These findings enhance our understanding of DOM dynamics in aquatic systems, particularly in mitigating antibiotic risks, and introduce innovative strategies in environmental management and water treatment technologies.
本研究旨在解决现有理解中存在的问题，即溶解有机质（DOM）各组分在抗生素光解过程中的具体作用，特别是在自然条件下和 DOM 光解过程中。本研究采用荧光、化学和分子分析技术，探索了细胞外和细胞内有机质（EOM 和 IOM）对多类抗生素光解的影响，以及在自然太阳辐射下 DOM 的光解。研究结果表明，DOM 各组分具有选择性光解，其驱动力是不同的化学特征，影响着 DOM 介导的抗生素光解。值得注意的是，脂质类物质在 IOM 中占主导地位，而木质素类物质在 EOM 中占主导地位，它们各自对阳光有独特的响应，并表现出选择性光解。阳光主要靶向 EOM 中的富里酸样木质素成分，与 IOM 中最初观察到的色氨酸样脂质物质的变化形成对比。EOM 的低光解性归因于其丰富的不饱和化合物，这导致了通过反应中间体增强的间接抗生素光解（0.339-1.402 h）的速率。相比之下，尽管 IOM 具有很高的光解性，但其中丰富的脂肪族化合物的光解性较低，对抗生素光解的介导作用较低（0.067-1.111 h）。三重态激发的 DOM*在抗生素的光转化和毒性降低中起着关键作用，突出了微生物 EOM 作为天然水生光敏剂在水自净化中的重要作用。这些发现提高了我们对水生系统中 DOM 动力学的理解，特别是在减轻抗生素风险方面，并为环境管理和水处理技术引入了创新策略。
