Environmental impact and variation analysis of different CaO2 and Ca(NO3)2 dosing modes on microbial community in black-odorous sediment

CaO 2 and Ca(NO 3 ) 2 are commonly used chemicals in the in-situ remediation of black-odorous sediments, but comparative studies on the impact on sediment microorganisms are scarce. This paper aimed to compare the impact of different CaO 2 and Ca(NO 3 ) 2 dosing modes on microorganisms in black-odorous sediments. The results showed that CaO 2 with single-dose in deep sediment performed best in removing nitrogen and phosphorus, while Ca(NO 3 ) 2 with multi-dose in shallow sediment was best in removing organic matter. After remediation, the abundance of sedimentary microbes increased significantly in each group. Microbial diversity in the CaO 2 group decreased while it increased in the Ca(NO 3 ) 2 group. Proteobacteria and Firmicutes were the predominant microbes in black-odorous sediments. The relative abundance of Proteobacteria and Firmicutes raised in each CaO 2 group, whereas Proteobacteria raised and Firmicutes declined in each Ca(NO 3 ) 2 group. Redundancy analysis demonstrated that microbes in black-odorous sediments were primarily influenced by NH 3 -N and COD in water. FAPROTAX functional prediction revealed that the microbial functional gene of thiosulfate-respiration was significantly increased in the CaO 2 group but decreased in the Ca(NO 3 ) 2 group. This research not only compares the impact of common chemicals on the microbial community of black-odorous sediments but also provides new data and findings for future in-situ remediation strategies of black-odorous sediments. • CaO 2 had a better removal effect on pollutants in water and sediment than Ca(NO 3 ) 2. • Ca(NO 3 ) 2 was more conducive to the stability of sedimentary microbes than CaO 2 . • Increased TN in Ca(NO 3 ) 2 group was associated with decreased Proteiniclasticum . • CaO 2 and Ca(NO 3 ) 2 significantly changed the microbial functional genes of thiosulfate-respiration .