Evaluating heavy metal pollution and potential risk of soil around a coal mining region of Tai’an City, China

Monitoring the spatial distribution characteristics of heavy metal pollution and evaluating its potential risks in the soil is essential for promoting regional socioeconomic development and maintaining the safety of the ecological environment. In this study, a representative coal mining region in Tai'an City, Chinas was selected as the study area, eight typical heavy metal elements (HMEs), i.g. Cu, Pb, Zn, Cd, Cr, As, Hg, Ni in the topsoil (0–20 cm) of 59 randomly generated sample sites were measured and monitored through sampling, testing and statistical analysis, and their spatial distribution patterns were analyzed accordingly. The single factor pollution index(SFPI) method, comprehensive pollution index (CPI) method and potential ecological hazard index (PEHI) method were employed to systematically computed and analyzed the single factor, comprehensive pollution and potential ecological risks of the selected HMEs in the soil. Results found that: (1) the average measured content of these elements all exceeded the referenced background value. The Cr element pollution was the lowest (3.39%), while the pollution of Ni, Cd and Hg elements were the highest (86.44%, 83.05 % and 81.36%, respectively). (2) The comprehensive pollution level was above mild pollution at all sample sites, and the comprehensive pollution was mainly ranged in the mild pollution level (59.32%); The moderate pollution level of comprehensive potential ecological risk accounted for 64.41%, and the spatial distribution was annular from northwest to southeast. (3) The values of potential ecological risk index indicated that Hg and Cd were the main pollution elements in this coal mining region, and Cd had the highest pollution rate. The findings of this study can be used to evaluate the pollution in other coal regions, and provide reference for the decision-making of soil heavy metal pollution control.