Aström J, Pettersson T J R, Stenström T A
Department of Civil and Environmental Engineering, Water Environment Technology, Chalmers University of Technology, SE-412 96, Göteborg, Sweden.
J Water Health. 2007;5 Suppl 1:67-79. doi: 10.2166/wh.2007.137.
Microbial contamination of surface waters constitutes a health risk for drinking water consumers which may be lowered by closing the raw water intake. We have evaluated microbial discharge events reported in the river Göta älv, which is used for raw water supply to the city of Göteborg. Elevated levels of faecal indicator bacteria were observed during periods of closed raw water intake. High bacteria levels were, however, also occasionally detected during periods of open intake, probably as a result of microbial discharge far upstream in the river which may be difficult to predict and manage by closing the intake. Accumulated upstream precipitations, resulting in surface runoff and wastewater contaminations in the catchment, correlated positively with the levels of total coliforms, E. coli, intestinal enterococci and sulfite-reducing clostridia. Levels of faecal indicator organisms were negatively correlated to the water temperature due to enhanced survival at lower temperatures. Wastewater discharges from a municipality located just upstream of the water intake resulted in elevated E. coli concentrations downstream at the raw water intake for Göteborg. To improve the prediction of microbial contaminations within the river Göta älv, monitoring data on turbidity and upstream precipitation are of particular importance.
地表水体的微生物污染对饮用水消费者构成健康风险，通过关闭原水取水口可降低这种风险。我们评估了哥特河（Göta älv）报告的微生物排放事件，该河为哥德堡市提供原水。在关闭原水取水口期间，观察到粪便指示菌水平升高。然而，在开放取水期间偶尔也检测到高细菌水平，这可能是由于河流上游很远处的微生物排放，通过关闭取水口可能难以预测和管理。集水区内上游累积降水导致地表径流和废水污染，与总大肠菌群、大肠杆菌、肠道肠球菌和亚硫酸盐还原梭菌的水平呈正相关。由于在较低温度下存活率提高，粪便指示生物的水平与水温呈负相关。位于取水口上游的一个市镇排放的废水导致哥德堡原水取水口下游的大肠杆菌浓度升高。为了改进对哥特河内微生物污染的预测，关于浊度和上游降水的监测数据尤为重要。
