[Health Risk Assessment of Heavy Metals in Agricultural Soils Around the Gangue Heap of Coal Mine Based on Monte Carlo Simulation].

Abstract

To analyze the pollution characteristics of heavy metals in the soil of farmland surrounding the gangue heap of a coal mine in Chongqing, the Nemerow, Muller, and Hakanson indices were used. Meanwhile, to investigate the health risks of heavy metals in soil, a health risk assessment model was employed using Monte Carlo simulation. The results revealed that the average contents of Cd, Hg, As, Pb, Cr, Cu, Ni, and Zn were higher than their soil background values, and the Muller index (Igeo) from high to low was as follows:Cd>Hg>Cu>As>Ni>Zn>Cr>Pb. The Nemerow index (PN) demonstrated that the results of the assessment indicated mainly light pollution (1<PN ≤ 2). The single factor index (Pi) from high to low was as follows:Cd>Cu>Ni>Cr>Zn>As>Pb>Hg. The Hakanson index (RI) demonstrated that the results of the assessment indicated mainly moderate ecological risk (150 ≤ RI<300). The single ecological risk index (Eri) from high to low was as follows:Cd>Hg>As>Cu>Ni>Pb>Cr>Zn. The health risk assessment of heavy metals revealed that the non-carcinogenic health risks of children and adults could be ignored, but carcinogenic health risks existed, with an average total carcinogenic risk index (TCR) of 1.04E-5 and 3.94E-6, respectively. The major carcinogenic factors were As and Cd. Sensitivity analysis of non-carcinogenic health risks revealed that the ingestion rate of soil (Ringest) was the most sensitive, followed by the contents of As. Meanwhile, sensitivity analysis of carcinogenic health risks indicated that the content of As was the most sensitive, followed by the ingestion rate of soil (Ringest). In general, the health risks of children, including non-carcinogenic and carcinogenic risks, were higher than those of adults.