Effects of long‐term coal gangue dumping on soil chemical environment and microbial community in an abandoned mine

Abstract

Coal gangue hill, a significant anthropogenic interference, can cause various forms of land degradation. The promoting effect of coal gangue on soil qualities has also been discovered. However, few studies investigated the soil properties and microbiome of prolonged gangue hills. Here, we investigated soil microbial communities and chemical properties in a vegetated gangue hill and adjacent cropland and wasteland (regarded as gangue‐free lands). We did not find any significant differences in the content of organic matter, total nitrogen, and total phosphorus between the gangue hill and the cropland (Kruskal–Wallis test, p > 0.05). The content of all metals we investigated (Pb, Ni, Sb, Fe, and Al) did not exceed the risk control values (GB 15618‐2018; GB 36600‐2018). The content of Fe and soil electrical conductivity of the gangue hill was significantly higher than the gangue‐free lands (about 2 times and 20 times, respectively), which were also the key factors shaping microbial communities (Mantel's test, p < 0.05). There were no significant differences in the composition of the bacterial communities between the gangue hill and gangue‐free lands. The random‐forest model identified four species belonging to Actinobacteria and Ascomycota as the unique species in the gangue hill. Functional annotation revealed that the significant differences between the two land types were in bacterial nutrition types, fungal saprophytic types, and nitrogen cycling. Our study provided a theoretical foundation for land management and sustainable utilization in abandoned mining areas.