Influence of Reclaimed Water on Bacterial Community structure of Sediment from 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 lowestproportions 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.