Linking microbial community and biological functions to redox potential during black-odor river sediment remediation.

The black-odor phenomenon in polluted urban rivers is a serious environmental problem that has received increasing attention in the recent years. The low redox potential (less than - 100 mV) in the sediment is considered to be the key factor causing the occurrence of black-odor phenomenon. Here, we studied the structure and function of the microbial community during the remediation of urban rivers. Results showed a clear improvement in water quality after undergoing river remediation processes. The on-site treatments showed a succession in the microbial composition and their predicted functions. The primary iron- and sulfur-reducing bacteria (Thiobacillus, Sulfuricurvum, and Sulfursoma) and the related reactions rapidly decreased after the dredging treatment but reappeared after a year. The structure and abundance of nitrogen and methane participants were also affected by river remediation process. These results indicated that although the water quality temporarily improved shortly after a dredging process, a recurrence of the black-odor phenomenon may occur as a result of the rebound in the microbial communities.