基于FIB的北京温榆河流域粪便污染物分布特征和源解析

目前,北京市温榆河流域存在着较为严重的粪源微生物污染问题,对流域周边暴露人群的健康带来了潜在的威胁.为了明确温榆河粪便污染的分布特征及宿主来源,本研究采用传统培养法与定量聚合酶链式反应(qPCR)分别对常规粪便指示细菌(Fecal indicator bacteria, FIB),包括粪大肠菌群(Fecal Coliform, FC)、大肠杆菌(Escherichia coli, EC)与肠球菌(Enterococcus,ENT)和溯源FIB,包括不同宿主来源的特异性生物标记进行检测,并探究其相关性.研究结果表明,流域内粪源微生物污染较为严重,常规FIB浓度介于0～4.38×10~7 CFU·L~(-1)之间,溯源FIB处于1.37×10~6～4.29×10~(10) copies·L~(-1)之间.从时空分布来看,由于来水中各大支流及污水处理厂的贡献,从温榆河起点沙河闸至终点北关闸,所有的指示菌浓度呈现出大幅度的升高趋势.其中,龙道河为干流来水中粪便污染的首要地域,污水处理厂的尾水可能是清河河口及坝河处微生物污染的主要来源;降雨径流对粪源微生物含量的时空变化存在着非常显著的影响,使得FIB最高可达2个数量级的增长.微生物溯源结果显示温榆河流域内的粪源微生物来源主要为人类粪便污染,而非畜禽粪便污染,这同北京市近年来有关畜禽养殖管控密切相关.相关性分析表明,虽然FC与EC、ENT之间皆存在着统计学意义上的显著正相关性,但传统的FIB指标与拟杆菌及人源拟杆菌指标之间不存在显著相关性.本研究通过传统FIB培养和微生物溯源方法结合,明确了北京温榆河粪源污染程度及其主要来源,为北京温榆河污染防控提供了新的思路.

Occurrence and source analysis of fecal pollutants in Wenyu River basin of Beijing based on FIB

The Wenyu River has been suffered from serious fecal microbial contamination, which poses a potential health threat. To identify the distribution characteristics and source of fecal contamination, the traditional microbial culture enrichment method and qPCR method were employed to detect conventional fecal indicator bacteria (FIB) including Fecal Coliform (FC), Escherichia coli (EC) and Enterococcus (ENT), as well as the source tracking FIB including specific biomarkers from different sources, respectively. In addition, the correlation between these two indicators was explored. The results show that there existed serious fecal contamination in Wenyu River Basin. The concentrations of conventional FIB ranged between 0~4.38×10⁷ CFU·L^-1; and the amplified copies of the source tracking FIB were between 1.37×10⁶~4.29×10¹⁰ copies·L^-1. From the perspective of temporal-spatial distribution, the concentration of all indicator bacteria increased significantly from Shahe Sluice at the origin of the Wenyu River to Beiguan Sluice at the ending point of Wenyu River, which was mainly contributed by major tributaries and wastewater treatment plants (WWTPs). Among them, Longdao River was the primary area of fecal pollution to the mainstem Wenyu River, and WWTPs appear to be the main source of microbial pollution in the Qinghe and Bahe Rivers; Rainfall runoff had a significant impact on the spatial and temporal variation of these fecal indicator, which increased FIB up to two orders of magnitude. The results of microbial source tracking show that the pollution of FIB in this basin were mainly from human feces instead of animal feces. Relevance analysis shows that there was a significant positive correlation between FC and EC, FC and ENT, but no significant correlation between traditional FIB and Bacteroides (include human Bacteroides). This study clarified the pollution degree of FIB and its source through the combination of conventional FIB culture and source tracking method, which provides a novel path forward for pollution control in the Wenyu River basin.