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Abstract：
Water-based opportunistic pathogens (OPs) are a leading cause of drinking-water-related disease outbreaks, especially in developed countries such as the United States (US). Physicochemical water quality parameters, especially disinfectant residuals, control the (re)growth, presence, colonization, and concentrations of OPs in drinking water distribution systems (DWDSs), while the relationship between OPs and those parameters remain unclear. This study aimed to quantify how physicochemical parameters, mainly monochloramine residual concentration, hydraulic residence time (HRT), and seasonality, affected the occurrence and concentrations of four common OPs (Legionella, Mycobacterium, Pseudomonas, and Vermamoeba vermiformis) in four full-scale DWDSs in the US. Legionella as a dominant OP occurred in 93.8% of the 64 sampling events and had a mean density of 4.27 × 105 genome copies per liter. Legionella positively correlated with Mycobacterium, Pseudomonas, and total bacteria. Multiple regression with data from the four DWDSs showed that Legionella had significant correlations with total chlorine residual level, free ammonia concentration, and trihalomethane concentration. Therefore, Legionella is a promising indicator of water-based OPs, reflecting microbial water quality in chloraminated DWDSs. The OP concentrations had strong seasonal variations and peaked in winter and/or spring possibly because of reduced water usage (i.e., increased water stagnation or HRT) during cold seasons. The OP concentrations generally increased with HRT presumably because of disinfectant residual decay, indicating the importance of well-maintaining disinfectant residuals in DWDSs for OP control. The concentrations of Mycobacterium, Pseudomonas, and V. vermiformis were significantly associated with total chlorine residual concentration, free ammonia concentration, and pH and trihalomethane concentration, respectively. Overall, this study demonstrates how the significant spatiotemporal variations of OP concentrations in chloraminated DWDSs correlated with critical physicochemical water quality parameters such as disinfectant residual levels. This work also indicates that Legionella is a promising indicator of OPs and microbial water quality in chloraminated DWDSs.
摘要：
水基机会病原体（OPs）是饮用水相关疾病暴发的主要原因，特别是在发达国家，如美国（US）。物理化学水质参数,尤其是消毒剂残留物，控制（重新）增长，存在,殖民,以及饮用水分配系统(DWDS)中OPs的浓度，而OPs与这些参数之间的关系尚不清楚。本研究旨在量化物理化学参数，主要是一氯胺残留浓度，水力停留时间（HRT），和季节性，影响了四种常见OPs的发生和浓度(军团菌，分枝杆菌,假单胞菌,和Vermamoebavermiformis）在美国的四个全尺寸DWDS中。军团菌作为显性OP发生在64个采样事件中的93.8％，平均密度为每升4.27×105个基因组拷贝。军团菌与分枝杆菌呈正相关，假单胞菌,和总细菌。4个DWDS数据的多元回归表明，军团菌与总氯残留水平具有显着相关性，游离氨浓度,和三卤甲烷浓度。因此,军团菌是水基OPs的一个有希望的指标，反映氯胺化DWDS中的微生物水质。OP浓度具有强烈的季节性变化，在冬季和/或春季达到峰值，可能是由于用水量减少(即，在寒冷季节增加水停滞或HRT）。OP浓度通常随着HRT而增加，大概是由于消毒剂残留的腐烂，指出了维持DWDS中消毒剂残留物对OP控制的重要性。分枝杆菌的浓度，假单胞菌,vermiformis和V.与总氯残留浓度显着相关，游离氨浓度,pH值和三卤甲烷浓度，分别。总的来说,这项研究证明了氯胺化DWDS中OP浓度的显着时空变化与关键的物理化学水质参数如消毒剂残留水平相关。这项工作还表明，军团菌是氯胺化DWDS中OPs和微生物水质的有希望的指标。
