Unrine Jason M, McCoy Nina, Christian W Jay, Gautam Yogesh, Ormsbee Lindell, Sanderson Wayne, Draper Ricki, Mooney Madison, Cromer Mary, Pennell Kelly, Hoover Anna G
Department of Plant and Soil Sciences, University of Kentucky, Lexington, Kentucky, United States of America.
Kentucky Water Research Institute, University of Kentucky, Lexington, Kentucky, United States of America.
PLOS Water. 2024;3(3). doi: 10.1371/journal.pwat.0000227. Epub 2024 Mar 4.
To increase our understanding of the factors that influence formation of disinfection byproducts (DBPs) in rural drinking systems, we investigated the spatial and seasonal variation in trihalomethane (THM) and haloacetic acid (HAA) concentrations in relation to various chemical and physical variables in a rural public drinking water system in Martin County, Kentucky, USA. We collected drinking water samples from 97 individual homes over the course of one year and analyzed them for temperature, electrical conductivity, pH, free chlorine, total chlorine, THMs (chloroform, bromodichloromethane, dibromochloromethane, dichlorobromomethane, and bromoform) and HAAs (monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, bromoacetic acid, and dibromoacetic acid). Spatial autocorrelation analysis showed only weak overall clustering for HAA concentrations and none for THMs. The relationship between modeled water age and TTHM or HAA5 concentrations varied seasonally. In contrast, there was strong variation for both HAA and THMs, with concentrations of HAA peaking in mid-summer and THMs peaking in early fall. Multiple regression analysis revealed that THM concentrations were strongly correlated with conductivity, while HAA concentrations were more strongly correlated with water temperature. Individual DBP species that only contained chlorine halogen groups were strongly correlated with temperature, while compounds containing bromine were more strongly correlated with conductivity. Further investigation revealed that increased drinking water conductivity associated with low discharge of the Tug Fork River, the source water, is highly correlated with increased concentrations of bromide. Discharge and conductivity of the Tug Fork River changed dramatically through the year contributing to a seasonal peak in bromide concentrations in the late summer and early fall and appeared to be a driver of brominated THM concentrations. Brominated DBPs tend to have higher toxicity than DBPs containing only chlorine, therefore this study provides important insight into the seasonal factors driving risk from exposure to DBPs in rural drinking water systems impacted by bromide.
为了增进我们对影响农村饮用水系统中消毒副产物（DBPs）形成因素的理解，我们在美国肯塔基州马丁县的一个农村公共饮用水系统中，研究了三卤甲烷（THM）和卤乙酸（HAA）浓度的空间和季节变化，并将其与各种化学和物理变量相关联。我们在一年的时间里从97个独立家庭收集了饮用水样本，并分析了样本的温度、电导率、pH值、游离氯、总氯、THMs（氯仿、溴二氯甲烷、二溴氯甲烷、二氯溴甲烷和溴仿）以及HAAs（一氯乙酸、二氯乙酸、三氯乙酸、溴乙酸和二溴乙酸）。空间自相关分析表明，HAA浓度仅有微弱的总体聚类，而THMs没有聚类。模拟水龄与总三卤甲烷（TTHM）或五卤乙酸（HAA5）浓度之间的关系随季节变化。相比之下，HAA和THMs都有很大变化，HAA浓度在仲夏达到峰值，THMs浓度在初秋达到峰值。多元回归分析表明，THM浓度与电导率密切相关，而HAA浓度与水温的相关性更强。仅含氯卤素基团的单个DBP种类与温度密切相关，而含溴化合物与电导率的相关性更强。进一步调查发现，作为水源的塔格福克河低流量导致饮用水电导率增加，这与溴化物浓度增加高度相关。塔格福克河的流量和电导率全年变化显著，导致夏末和初秋溴化物浓度出现季节性峰值，这似乎是溴化THM浓度的驱动因素。溴化DBPs的毒性往往比仅含氯的DBPs更高，因此本研究为受溴化物影响的农村饮用水系统中接触DBPs所致风险的季节性驱动因素提供了重要见解。
