干湿季节下再生水补给河流的溶解性有机物组成特征及其与致病菌基因的相互关系

Characteristics of dissolved organic matter and its correlation with pathogenic genes for river replenished by reclaimed water in wet and dry seasons

水体中溶解性有机物(DOM)对各种类型污染物的迁移转化具有重要影响.为了考察干湿季节下再生水补给水体的DOM分子多样性变化及其主要成分对致病菌分布及迁移的影响,本研究以北京两个典型的再生水补给水体(清河和沙河水库)为对象,分别在旱季和雨季采集水样,采用三维荧光光谱(3D⁃EEM)、平行因子分析(PARAFAC)、光谱指数(FI、HIX和BIX)和1H⁃NMR等方法分析水样的DOM,并采用定量PCR测定目标致病菌基因(ecfX、mcr1、gltA、tcpA和23S rDNA)的相对丰度.结果发现,清河和沙河水库水样的DOM分别为5个和4个组分,主要以自生源为主,且微生物活性较高,降雨会导致腐殖酸类有机质的输入.1H⁃NMR分析表明,清河和沙河水库水样中DOM有6个氢核基团,旱季以烷氧基和脂肪族羟基基团为主,雨季则以羧基或芳香环氢核基团为主.相关性分析结果表明,旱季致病菌基因的相对丰度与DOM特征组分的相关性较弱;雨季DOM更利于与致病菌表面吸附,致病菌基因的相对丰度与CH3、CH、CHO/N、HAr、Hp和CH⁃α呈显著相关性(p<0.05).

Dissolved organic matter(DOM)is widely distributed in the aquatic environment in which fluvial networks are globally pertinent to the processing of DOM,and plays an important role in the migration and transformation of various types of contaminants,such as heavy metals,organic pollutants,endocrine disrupters(EDC)and bacterial or pathogens.To investigate the diversity and molecular characteristics of DOM in the river replenished by reclaimed water and compare the change of DOM composition at different seasons,one river and one reservoir receiving effluent from the typical reclaimed water treatment plants were selected to take samples in dry and wet seasons.Spectral index(FI,HIX and BIX),EEM⁃PARAFAC,and 1H⁃NMR were applied to determine the DOM.And quantity PCR was applied to measure the relative abundance of the pathogenic genes including ecfX,mcr1,gltA,tcpA and 23S rDNA to study their correlation with DOM.The results showed that DOM for the Qinghe River and Shahe Reservoir were divided into five and four components,respectively,which were mainly composed of microbial endogenous metabolites with high bioavailability and low degree of humidity.A positive correlation was found between DOM components(CH3,CH,CHO/N,HAr,Hp and CH⁃α)and relative abundance of pathogenic genes(p<0.05)in the Shahe Reservoir during the wet season.