Spatial distribution, sources and health risk assessment of heavy metals in shallow groundwater in a typical coal mining area in Huainan, China

The availability of uncontaminated groundwater is of pivotal significance for the sustainable sustenance of human development. High concentrations of heavy metals in groundwater can pose substantial risks to human health. This study explores the spatial distribution patterns, sources of pollution, and health risk assessment of heavy metals (Mn, Ni, U, Zn, V, Cu, Cr, Cd and Pb) in the shallow groundwater of the Huainan coal mining area in China. The concentrations of Mn and Ni were found to be relatively high. The spatial distribution characteristics of the heavy metals were analyzed using inverse distance weighting, revealing that the spatial distribution of V, Ni, Cd, Pb and U was similar, suggesting characteristics of typical point source pollution. The PMF model indicated that mining activities, industrial sources and local geogenic processes were the main factors affecting groundwater quality, with contributions of 42.76%, 440.78% and 16.46%, respectively. The health risk assessment results demonstrate that the non-carcinogenic risk of each heavy metal is within the safety threshold; however, the carcinogenic risk posed by Ni should not be overlooked. It is observed that the carcinogenic risk and non-carcinogenic risk values for children exceed those for adults. Consequently, groundwater in the study area must undergo specific purification measures before utilization. The findings of this study offer a scientific foundation for ensuring the quality of groundwater and the safety of drinking water in plain areas affected by coal mining.