A study on soil basic characteristics, main microbial flora and typical metal fraction surrounding coal gangue dump in Xiangtan Hunan Province, south of China

Abstract

During the coal ore mining and utilization process, coal and its associated minerals have been discharged as coal gangue. Upon interacting with the water, air and microbial oxidation, the harmful metals and sulfides in coal gangue will cause serious pollution. In present work, the basic chemical characteristics, main microbial flora and typical metal speciation of the soil around coal gangue dump in Liejiaqiao coal mine, xiangtan mining area, Hunan province south of China were analyzed with several methods including XRF, XRD, microbial plate culture count and Tessier’s sequential extraction scheme. Correlation, cluster and principal component analysis (PCA) were used to estimate the possible main factors of coal gangue dump’s effect on surrounding soil and their correlation with microbial flora. Research results showed that the soil surrounding the coal gangue dump had low pH and microbial abundance (including bacteria, fungi and actinomycete). The soil samples contained high levels of metals especially for Mn, Fe and Cr. Tessier’s sequential extraction results showed that Fe, Mn and Cr were mainly associated residual fraction. Risk assessment revealed that Fe and Cr had lower risk than Mn to the surrounding environment. Based on PCA and cluster analysis results, the obtained ten samples can be divided into three groups. Among of them, mobile fraction of metals, microbial abundance could be the main factor reflecting the soil pollution around the coal gangue dump. Furthermore, correlation analysis showed that the abundance of bacteria and actinomycete had significant relationship (at 0.05 levels) with mobility factor of Fe and pH condition of the soil samples, respectively.