Distribution and Variation of Soil Bacterial Community of Two Lead-Zinc Tailings in Qinling Mountains

MiSeq high-throughput sequencing methods were used to study the bacterial diversity and community structure composition of Pb-Zn tailing soils in the Qinling Mountains (in the case of Bijiashan and Yanzibian), and to analyze their correlation between soil chemical properties and heavy metal concentrations. The differences between the two mine tailings were compared to summarize and analyze the main influencing factors on the soil bacterial community structure of the tailings. The results showed that the soils of the two tailings were polluted by heavy metals to different degrees, and the polluted degree of the tailings in Bijiashan was significantly higher than that of Yanzibian. Proteobacteria, Actinobacteria, Acidobacteria, Chlorella, and Firmicutes were the main dominant phyla in tailing soils. Specifically, the relative abundance of bacterial communities of Proteobacteria and Acidobacteria in the polluted soil showed a general upward trend compared with the control. On the contrary, the relative abundances of Actinobacteriota and Chloroflexi showed a decreasing trend in the contaminated soil compared with the control. Redundancy analysis (RDA) and Variance Partitioning Analysis (VPA) showed that soil chemical properties and heavy metal concentrations affected bacterial community structure jointly. Specifically, soil organic matter (SOM), total organic carbon (TOC), total potassium (TK), total phosphorus (TP), and total nitrogen (TN) are the positive influencing factors of bacterial community structure, while heavy metals Cd, Pb, Zn, Cu is a negative factor affecting bacterial community structure. We further concluded that the main influencing factors of tailing soil bacterial community structure were pH, SOM, TN and heavy metals Cd, Zn, and Pb. In addition, the effects of heavy metal contamination did not exceed the effects of soil physicochemical properties on tailing soil bacterial community structure in these two tailings.