Influence Pathways of Vanadium Stress to Microbial Community in Soil-Tailings-Groundwater Systems

The large-scale exploitation of vanadium (V) bearing minerals has led to a massive accumulation of V tailings. Although the mechanism of V stress to the microbial community have been reported, how V stress on the microbial communities at the same geographical location but in different depth of environmental media (e.g., groundwater and soil) is unknown and its influence pathway is also unclear. The dynamic redox conditions and substance exchange within the soil-tailings-groundwater system exhibited complex V stress on the regional microbial communities. In this study, the influence pathways of vanadium stress to microbial community in the soil-tailings-groundwater system were first investigated via geochemical and biological analysis. The results showed that V, Mn, and Fe were the primary metal contaminants in the groundwater and soil. The concentrations of most metals were higher at low elevations. Distinct microbial composition was observed among soils, tailings, and groundwater, in which soils had the highest level of microbial community diversity and richness. These phyla, including Firmicutes, Proteobacteria, Actinobacteria, and Acidobacteria, were dominant in all the three environmental media. Microbial communities could be affected by a variety of environmental factors including V, Cr, Fe, Mn, pH, OM, TOC, TN, and TP, among which V was the key driver. The pathways of V affecting microbial diversity and abundance in diverse environmental media were different. Groundwater microbial communities were influenced by V through Cr, DO, and TN, while Fe, Mn, and TP were the key mediators in soils. V was demonstrated as the key variable affecting the tailings reservoir microbial community by influencing metabolic pathways related to carbonaceous matter, which was involved in the establishment of survival strategy for metal stress. This study provides novel insights into the influencing pathway of V on the microorganisms in tailings reservoir and potential V reducing bacteria for pollution bioremediation.