The multiple reactive oxidants produced during chlorine photolysis effectively degrade organic contaminants during water treatment, but their role in disinfection byproduct (DBP) formation is unclear. The impact of chlorine photolysis on dissolved organic matter (DOM) composition and DBP formation is investigated using lake water collected after coagulation, flocculation, and filtration at pH 6.5 and pH 8.5 with irradiation at three wavelengths (254, 311, and 365 nm). The steady-state concentrations of hydroxyl radical and chlorine radical decrease by 38–100% in drinking water compared to ultrapure water, which is primarily attributed to radical scavenging by natural water constituents. Chlorine photolysis transforms DOM through multiple mechanisms to produce DOM that is more aliphatic in nature and contains novel high molecular weight chlorinated DBPs that are detected via high-resolution mass spectrometry. Quenching experiments demonstrate that reactive chlorine species are partially responsible for the formation of halogenated DOM, haloacetic acids, and haloacetonitriles, whereas trihalomethane formation decreases during chlorine photolysis. Furthermore, DOM transformation primarily due to direct photolysis alters DOM such that it is more reactive with chlorine, which also contributes to enhanced formation of novel DBPs during chlorine photolysis.

中文翻译：

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氯光解过程中活性卤素物质在消毒副产物形成中的作用。

氯光解过程中产生的多种活性氧化剂可有效降解水处理过程中的有机污染物，但它们在消毒副产物 (DBP) 形成中的作用尚不清楚。氯光解对溶解有机物 (DOM) 组成和 DBP 形成的影响使用在 pH 6.5 和 pH 8.5 下经过三个波长（254、311 和 365 nm）的照射后收集的湖水进行了研究。与超纯水相比，饮用水中羟基自由基和氯自由基的稳态浓度降低了 38-100%，这主要归因于天然水成分的自由基清除。氯光解通过多种机制转化 DOM，以产生本质上更脂肪族的 DOM，并含有通过高分辨率质谱法检测到的新型高分子量氯化 DBP。淬灭实验表明，活性氯物质是形成卤代 DOM、卤代乙酸和卤代乙腈的部分原因，而氯光解过程中三卤甲烷的形成减少。此外，主要由于直接光解引起的 DOM 转化会改变 DOM，使其与氯的反应性更强，这也有助于在氯光解过程中增强新型 DBP 的形成。淬灭实验表明，活性氯物质是形成卤代 DOM、卤代乙酸和卤代乙腈的部分原因，而氯光解过程中三卤甲烷的形成减少。此外，主要由于直接光解引起的 DOM 转化会改变 DOM，使其与氯的反应性更强，这也有助于在氯光解过程中增强新型 DBP 的形成。淬灭实验表明，活性氯物质是形成卤代 DOM、卤代乙酸和卤代乙腈的部分原因，而氯光解过程中三卤甲烷的形成减少。此外，主要由于直接光解引起的 DOM 转化会改变 DOM，使其与氯的反应性更强，这也有助于在氯光解过程中增强新型 DBP 的形成。