Geochemical properties, heavy metals and soil microbial community during revegetation process in a production Pb-Zn tailings
Lead-zinc (Pb-Zn) tailings pose a significant environmental threat due to heavy metal (HM) contamination. However, an advanced understanding of the changing characteristics of HMs and evolution of microbial community during revegetation process remain limited. This study investigated the spatial distribution of HMs and the role of soil microbial communities during three-year revegetation in a production Pb-Zn tailings. Field sampling and laboratory analysis revealed distinct enrichment patterns of representative HMs, including Cr, Mn, Pb, and Zn, within the tailings. Prolonged stockpiling of tailings exacerbated Pb contamination, resulting in increased concentrations (from 10.11 g/kg to 11.53 g/kg) in the long-term weathering area. However, the revegetation efforts effectively mitigated Pb contamination, leading to a significant reduction in Pb levels (a reduction of 9.81 g/kg). Through 16S rRNA gene amplicon sequencing, the dominant genera shifted from Weissella (44%) to Thiobacillus (17%) and then to Pseudomonas (comprising 44% of the sequences) during the revegetation process. Pseudomonas emerged as the dominant genus in revegetation area, comprising 44.17% of the sequences. Conversely, Thiobacillus prevailed in weathering area, accounting 16.64% of the sequences. Structural equation modeling indicated that Pseudomonas exhibited significant remediation potential by transforming highly bioavailable Pb into a more stable form. This study provides essential evidence of HM contamination and microbial community dynamics during Pb-Zn tailings revegetation, contributing to the development of sustainable microbial technologies for tailings management.