Distribution, source and health risk assessment based on the Monte Carlo method of heavy metals in shallow groundwater in an area affected by mining activities, China

Mining activities exert a far-reaching impact on the quality of groundwater, and health problems caused by heavy metal pollution have attracted global attention. In this study, inductively coupled plasma-mass spectrometry (ICP-MS) was employed to determine the contents of 8 heavy metals (Cd, Cr, As, Fe, Mn, Cu, Zn, and Pb) in shallow groundwater samples retrieved from a mining area in northern Anhui. Multivariate statistical methods were adopted to analyze the distribution and source of pollution and to evaluate 5% and 95% health risks based on Monte Carlo simulation. Fe, As and Cr significantly exceeded the safe drinking water standards of the World Health Organization (WHO). The average concentrations of As and Cr were as high as 46.45 μg/L and 133.96 μg/L, respectively. The correlation analysis and principal component analysis (PCA) results revealed that heavy metals are affected by complex factors, the main factor being human activities. The total carcinogenic health risks of Cr and As in adults were 2.49 × 10^-3 and 3.43 × 10^-4, respectively, which exceeded the maximum acceptable risk value (1 × 10^-4) recommended by the United States Environmental Protection Agency (USEPA), affecting human health. According to the USEPA classification of hazardous ingestion (HI), at HI < 1, the impact of non-carcinogenic heavy metals on human health is negligible. These results indicate that local residents should strengthen the monitoring of Cr and As pollution in shallow groundwater.