Dynamic Changes of Soil Parameters and Bacterial Communities during Bioremediation of Multiple Heavy Metals Contaminated Tailings by Compound Bacterial Flora

Abstract

Abstract Many researchers have paid attention to solving the problem of multiple heavy metals pollution in the tailings area. However, the studies only stay at the laboratory level, which cannot completely demonstrate an efficient approach to remediate polluted environment due to tailings. This study aimed at investigating the effects of compound bacterial flora we constructed to remediate the tailings area of Linze County, Zhangye City, Gansu Province due to the accumulation of numerous heavy metals such as Pb, Cd and Mn. The remediation effects of different treatment groups were evaluated by monitoring the physical and chemical properties of soil and studying the bacterial community structure during the remediation process. Compared with the control (TCK), after 84 days of restoration, parameters of the tailings soil inoculated with the compound bacterial flora were improved, pH was decreased from 7.74 to 7.02, EC (electrical conductivity) was decreased by 21.15% ~70.49%, and activities of alkaline phosphatase, sucrase and urease were increased by 95.94%~99.64%、88.42%~98.43%、83.28%~86.95% respectively. Among the 43 identified core optional taxonomic units (OTUs), Proteobacteria (44.9%), Actinobacteriota (21.7%), Bacteroidota (17.9%) were the dominant bacterial phyla, and Sphingobacterium (20.2%), Arthrobacter (8.5%), Sphingomonas (6.1%) were the dominant bacterial genus. The results of alpha diversity showed that the bacterial diversity and richness of the treatment groups inoculated with compound bacterial flora were significantly higher than controls (TCK and HCK). The correlation analysis of RDA, VPA and Spearman showed that soil pH, WHC, EC, POR, TEMP and heavy metals had significant effects on the composition and distribution of bacterial communities. Our study monitored the changes of soil physical and chemical properties and bacterial community structure during the whole remediation process, which will provide a reference basis for the remediation approach to the soil polluted by multiple heavy metals.