基于指示菌的温榆河微生物健康风险评估

城市河流是城市重要的生态景观组分,发挥着一定的景观娱乐功能,但污水处理厂出水和流域分散性污水等非常规水源补给逐渐成为越来越多城市河流补给的常态.本研究在典型的非常规水源补给河流—北京市温榆河布设采样点,系统评估了2015年间河流的粪大肠菌、大肠埃希氏菌、肠球菌3种指示微生物的污染状况,运用定量微生物风险评价方法考查了非常规水源补给对河流微生物污染状况和微生物的人体健康风险的影响.研究结果显示,温榆河作为景观娱乐水体时,以不同表征方式表征的单次暴露微生物健康风险值为0.1~0.5,从风险角度考虑其作为景观娱乐水体是不可接受的;受非常规水源补给影响严重的下游河段单次暴露的健康风险可能比上游高出50%.从温榆河不同微生物表征的单次暴露健康风险来看,上下游暴露途径皆以游泳引起的风险为最高;从微生物年暴露健康风险来看,对河道保洁人员、游船驾驶人员这两类常年频繁接触温榆河水体的人群风险值最高.

Health risk assessment based on indicator microorganisms in Wenyu River

The urban river in North China are mostly replenished with unconventional water supplies. E.g. effluent from wastewater treatment plant and decentralized wastewater. Meanwhile, urban rivers are important ecological parts of the city and play a significant role in landscape/recreational function. Thus, the risk of effluent replenished urban river is needed to be evaluated. This study monitored sampling points set along Wenyu River-a typical unconventional river and systematically studied the indicator bacteria including fecal coliform(FC), Escherichia coli(EC), and enterococcus(ENT) in 2015. The influence of unconventional water on microbial pollution status and health risk is assessed by Quantitative Microbial Risk Assessment Method(QMRA). The results show that:1calculated with different dose-response equations, the value of the single exposure microbial risk of Wenyu River is in the range of 0.1 to 0.5, indicating most are unacceptable. The health risk of a single exposure by contacting downstream water that is heavily affected by unconventional replenished water may be as much as 50% higher than the upstream water. The results of risk assessment obtained from different dose-response relationships have some similarities.2Considering the one-time exposure health risk characterized by different microbes in Wenyu River, the exposure risk caused by swimming in both upstream and downstream was the highest in the four exposure pathways discussed in this study. By the one-year health risk characterization, river cleaning staff and cruise drivers who frequently contacted the water are faced with higher health risks.