冬季不同尾水受纳河道水环境变化特征分析

VARIATION CHARACTERISTICS IN WATER ENVIRONMENT OF DIFFERENT TAILWATER RECEIVING RIVERS IN WINTER

为探究不同污水厂尾水受纳河道水环境变化特征,分别采集4组受纳河道的33个样品,测定COD_(Mn)、TN、TP、NH_(3)-N、Chl-a 5项指标,结合高通量测序,分析沿程水质变化、富营养化特征及细菌群落结构变化。结果表明:尾水排口处引起的污染物浓度变化在距离排口50~100 m恢复至背景值,但TN始终高于背景值;尾水补充使细菌丰富度及多样性增加,但优势门类占比下降且相对丰度改变,距离排口50~100 m处占比回升,Proteobacteria成为绝对优势菌门;属水平上,背景断面优势菌属相对丰度随着尾水排入均出现下降,Rhodovulum、Pseudoalteromonas、Massilia占比与富营养化指数显著负相关(P<0.05);当排放比例≥50%时,距离排口100 m处细菌群落结构与尾水排口处相似度更高。此外,尾水可能带来大量其他菌种,增加河道生态风险。

To study the characteristics of water environment changes in different tail water receiving rivers,33 samples were collected from 4 groups of the rivers,and five indicators,COD_(Mn),TN,TP,NH_(3)-N and Chl-a,were determined. Combined with high-throughput sequencing,the water quality changes,eutrophication characteristics and bacterial community structure were analyzed along the distance. Results showed that: the change of pollutant concentration caused by tailwater would recover to background value within 50~ 100 m except TN. The supplement of tailwater increased the bacterial richness and diversity,but the proportion of dominant species decreased and their relative abundance changed. After 50 ~ 100 m,the proportion began to increase and Proteobacteria became the absolute dominant phylum. At the level of genus,the relative abundance of dominant bacteria in background section all decreased with supplement of tailwater, while the abundance of Rhodovulum,Pseudoalteromonas,Massilia were significantly negative correlated to river eutrophication index( P<0. 05). When the discharge ratio was ≥ 50%,the similarity of bacterial community structure between downstream and tailwater outlet was higher. In addition,tailwater may bring a large number of other microbial species,causing an increase in ecological risk of river.