再生水补水对河道底泥细菌群落结构的影响

以北京市永定河麻峪湿地再生水补水口附近河道底泥为研究对象,应用末端限制性片段长度多态性(Terminal Restriction Fragment Length Polymorphism,T-RFLP)技术探究再生水补水口附近底泥细菌群落结构的空间差异特征以及环境因子所产生的影响,并借助典范对应分析(Canonical Correspondence Analysis,CCA)方法分析麻峪湿地底泥细菌群落结构空间差异特征的形成原因。分析结果表明:河道底泥微生物群落对再生水的净化主要发生在距补水口1200m的范围内,随着再生水与上游来水径向混合净化渐变过程,在补水口2000m处河道底泥微生物群落结构与河道再生水补水口上游趋于相似。基于样点聚类结果的群落结构多样性分析表明随着再生水净化过程的实现微生物综合多样性指数呈现下降的趋势,从均匀度指数的变化趋势看,再生水补水口具有最高均匀度指数,补水口下游1200米处由于非优势菌群所占相对丰度最低以及偶见菌群缺失,导致群落结构比较单一、群落多样性和均匀度指数都最低。CCA方面分析结果表明再生水补水口上游细菌群落与因累积效应形成的重金属有密切关系,补水口出口底泥细菌群落则主要受到总磷和总有机碳的影响较大,而再生水补水与上游来水汇水径向渐变过程可能与氨氮净化具密切关系。研究区的主要优势菌种为假单胞菌属、贪食菌属和芽孢杆菌属,是与再生水中有机碳、氮降解具有密切关系的菌属。

Influence of reclaimed water on the bacterial community structure of sediment from an urban river

We investigated changes in bacterial community structure and diversity in urban river sediment in a Mayu wetland upon addition of reclaimed water. We employed a range of analytic procedures, including terminal restriction fragment length polymorphism (T-RFLP), hierarchical clustering, the diversity index, and canonical correspondence analysis (CCA), to provide a general framework for the estimation and statistical testing of effects on local biological communities. As expected, our results showed that water purification occurred over the 1200 m range downstream of the reclaimed water outfall. The bacterial community structure found in sediment beyond 2000 m downstream of the outfall was similar to that of sediment found upstream. Shannon-Wiener index values declined from the outfall to 1200 m downstream, along the area of reclaimed water purification. This was consistent with the observed decline in the evenness index, which was at a maximum at the outfall and reached its minimum value at the 1200 m point, a section characterized by the lowest proportions of non-dominant bacteria and a lack of rare bacteria. In contrast, CCA results revealed a close relationship between the bacterial community in the upstream sample and the accumulation of heavy metals. The bacterial community at the outfall was mainly influenced by total phosphorus and organic carbon, suggesting a crucial role for the biological purification of ammonia during mixing of reclaimed water and upstream river water. In addition, we found that the major genera occurring in the studied areas (Pseudomonas, Variovorax, Streptomyces, and Bacillus) were implicated in the biodegradation of organic carbon and nitrogen in reclaimed water.