Arsenic (As) and antimony (Sb) are toxic metalloids with similar physicochemical properties, and their microbial transformation is closely linked to carbon (C), nitrogen (N), and sulfur (S) cycling. Mining-related anthropogenic activities substantially alter the bioavailability of As/Sb and microbial metabolism, but the specific impacts of sequential mining, dressing, and smelting processes on microbial communities and C, N, S, and As/Sb cycling remain unclear. In this study, we systematically investigated soil physicochemical properties, microbial communities, and functional potentials in an abandoned Sb mine area. The results showed that different mineral processing stages significantly altered soil nutrient status and heavy metal distribution, and induced distinct shifts in microbial diversity, composition, and metabolic potential. The mining area exhibited the lowest bacterial α-diversity, whereas the smelting area supported the highest diversity. Metal-tolerant taxa, including Proteobacteria, Actinobacteria, and Firmicutes, were enriched in the mining area, with dominant genera such as Pseudomonas, Bacillus, and Bradyrhizobium. Functional analyses indicated clear stage-specific differentiation of microbial metabolism: the dressing area was characterized by enhanced iron-related respiratory potential, the smelting area by increased methyl compound utilization, and the mining area by stronger sulfur oxidation and organic matter degradation potential. Metagenomic analysis further revealed that the reductive citric acid cycle was the dominant carbon fixation pathway, while smelting activities increased the relative abundance of genes involved in nitrate transformation, sulfur metabolism, and As/Sb resistance. Core taxa including Streptomyces, Sphingopyxis, Sphingomonas, and Pseudomonas were broadly associated with C, N, S, and As/Sb cycling across all sites. This study provides new insights into how sequential mining, dressing, and smelting activities shape microbial community assembly and biogeochemical functions in metalloid-contaminated soils. The findings have broader relevance for understanding microbial adaptation and for developing site-specific bioremediation strategies in similar mining-impacted environments worldwide.
Zhang et al. (Fri,) studied this question.