Site Remediation of Multiple Heavy Metals Contaminated Iron Tailings by Compound Bacterial Flora Combined with Peganum harmala

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 iron tailings. This study aimed at investigating the effects and mechanisms of compound bacterial flora combined with peganum harmala 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 preliminary experiment was conducted in the laboratory to obtain data that should be compared with the tailings data. Compared with the control, 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 7.18, the 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. The improvement of soil parameters was more evident in the treatment groups inoculated with compound bacterial flora and Peganum harmala. The results of high-throughput sequencing at different remediation stages showed that the structure of the soil microbial community changed after inoculation with compound bacterial flora, but the dominant species remained unchanged, only their relative abundance changed. At the phylum level, the dominant species in T (total tailings soil treatment groups) were Proteobacteria, Bacteroidota and Actinobacteriota, while the dominant species in 3:1 (H: add yellow cinnamon soil treatment groups) were more than Chloroflexi and Acidobacteriota. According to the analysis of Heatmap, the environmental factors such as pH, WHC, EC, Pb, Cd and Mn have evinced a significant impact on the bacterial community structure. This study provides a reference basis for the remediation approach to the soil polluted by different heavy metals.