Biochar had been widely used to improve the activity of photocatalysts, the biochar-based photocatalysts had more potential for environmental pollution remediation, but their effect on the sediment remained unknown. To understand these, the typical photocatalyst g-C3N4 was modified by biochar to develop g-C3N4/biochar with enhanced photocatalytic ability. Riverbed sediment was exposed to g-C3N4 and g-C3N4/biochar respectively for 30 days, and Illumina sequencing was utilized to examine the changes in the bacterial community in the sediment. The results showed that in riverbed sediment, g-C3N4 exposure had a concentration-dependent effect on the diversity of bacteria, while g-C3N4/biochar exposure had a slight influence on the bacterial diversity and the diversity almost maintained stable with different g-C3N4/biochar concentration. The application of g-C3N4 exhibited an inhibition influence on the growth of Acidobacteria, Gemmatimonadetes, and Rokubacteria in sediment, whose relative abundance increased when g-C3N4 was 25 mg/kg, and then decreased when g-C3N4 beyond this concentration. The presence of g-C3N4/biochar increased the relative abundance of Cyanobacteria in sediment and showed no obvious impact on other dominant phyla. Both g-C3N4 and g-C3N4/biochar could alter the levels of TP, NN, and AN in the sediment, but the magnitude of the changes of these physicochemical factors caused by g-C3N4/biochar was much smaller than those caused by g-C3N4. In addition, the complexity of the bacterial community network was reduced in a high concentration of g-C3N4, while it remained stable with different concentrations of g-C3N4/biochar treatments. Totally, this study demonstrated that, compared to g-C3N4, g-C3N4/biochar was able to maintain the relative stability of the bacterial community in riverbed sediment and mitigate the negative effects of photocatalysts to some extent, making biochar an ecological remediation agent with great potential for application.
Keywords: Bacterial community; Biochar; Network analysis; Riverbed sediments; g-C3N4/biochar.
© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.