Total organic chlorine (TOCl), bromine (TOBr) and iodine (TOI) species and collectively total organic halide (TOX) concentrations were quantified quarterly at 11 US drinking water treatment plants (WTPs) and distribution systems. TOCl was the dominant halogen-specific TOX species in most plants. TOBr concentrations varied with source water bromide (Br⁻) concentrations at WTPs. TOI was always below the minimum reporting level even though iodine species were present at >1 μg L⁻¹ in some source waters. Ratios of TOCl to TOBr varied seasonally. TOCl increased as intake DOC increased in some plants. Seasonal changes in raw water Br⁻ concentration did not lead to the corresponding variations in TOBr concentrations for most WTPs. For WTPs practicing chloramination, TOCl and TOBr concentrations did not increase significantly from the effluent into their distribution systems. Chlorine contact time for both pre-oxidation and post-chlorination prior to ammonia addition was the most important factor affecting the TOX formation in WTPs. On the other hand in distribution systems with free chlorine residuals, TOCl and TOBr concentrations increased as long as residual chlorine was available. Despite seasonal variations, the ratios of regulated brominated disinfection by-products to TOBr (i.e., Br-DBP/TOBr) were lowest for chloraminated plants treating groundwater and generally higher for WTPs utilizing free chlorine. We observed TOBr levels as high as 116 μg L⁻¹ in one distribution system, while the ratio of regulated brominated DBPs to TOBr was as low as 15% in some systems indicating that the major portion of TOBr in the finished water is unidentified and unmeasured. Given the higher toxicity of brominated DBPs than their chlorinated analogs, it is important to develop treatment and/or operational strategies to reduce the formation of TOBr in distribution systems in order to minimize exposure of the public to such DBPs.

中文翻译：

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饮用水分配系统中不同位置的总有机卤素（TOX）物种形成

在美国的11家饮用水处理厂（WTP）和分配系统中，每季度对总有机氯（TOCl），溴（TOBr）和碘（TOI）种类以及总有机卤化物（TOX）浓度进行定量。在大多数植物中，TOCl是主要的卤素特异性TOX物种。TOBr浓度的源水溴化物（BR变化^- ）的浓度在水厂。即使在某些水源水中碘的含量> 1μgL ^-1，TOI始终低于最低报告水平。TOCl与TOBr的比例随季节变化。随着一些植物中DOC的摄入量增加，TOC1增加。季节变化在原水中溴^-对于大多数污水处理厂来说，浓度没有导致TOBr浓度的相应变化。对于采用氯化法的污水处理厂，从废水进入其分配系统后，TOCl和TOBr的浓度并未显着增加。加入氨之前，预氧化和后氯化的氯接触时间是影响WTP中TOX形成的最重要因素。另一方面，在具有游离氯残留物的分配系统中，只要有残留氯存在，TOCl和TOBr的浓度就会增加。尽管季节性变化，但受管制的溴化消毒副产物与TOBr的比率（即（Br-DBP / TOBr）在处理地下水的加氯工厂中最低，而在使用游离氯的污水处理厂中通常更高。在一个分配系统中，我们观察到TOBr含量高达116μgL ^-1，而在某些系统中，溴化DBP与TOBr的比例低至15％，这表明最终水中TOBr的大部分未被识别和测量。鉴于溴化DBP的毒性比其氯化类似物更高，因此重要的是制定治疗和/或操作策略以减少分配系统中TOBr的形成，以最大程度地减少公众对此类DBP的接触。