Pollution Characteristics and Health Risks of Heavy Metals in the Groundwater of a Chemical Industrial Park

Abstract This study investigated the heavy-metal pollution characteristics of a chemical industrial park in southern China and conducted a health risk assessment on the groundwater. A total of 127 groundwater samples were collected at the site, and the concentrations of 11 heavy metals were systematically determined. The single-factor pollution index, the Nemero comprehensive pollution index and Pearson correlation analysis were used to explore the pollution characteristics, spatial distribution and source relationships of the heavy metals, and the health risk assessment was conducted by coupling the United States Environmental Protection Agency model with the Monte Carlo simulation method to account for uncertainty. Amongst the heavy metals, Fe had the highest mean concentration followed by Mn, Al, Zn, Co, Ni, Pb, Cu, Cd, As and Tl.All heavy metals exceeded the Class III values specified in the GB/T 14848 − 2024 standard for drinking water (i.e. suitable with minimal treatment) except for Cu. According to Nemero comprehensive pollution indices, the Fe, Al, Tl, Pb and Ni concentrations corresponded to severe pollution while the Cd and Co concentrations corresponded to slight pollution. Industrial activities were found to have a notable impact on the concentrations of all heavy metals. In terms of spatial distribution, Al, Mn, Fe and Tl were found throughout the study area while Cd, Co, Ni and Pb had hotspots in the north-central part and lower concentrations in the southern and eastern parts. Pearson correlation analysis identified strongly positive correlations amongst Zn, Al, Cd, Ni and Co. Mn had a significant correlation with most elements while Pb was relatively independent. The health risk assessment indicated that the mean non-carcinogenic hazard index exceeded the safety threshold for both adults and minors. Mn and Co were the core driving factors, and adults faced a higher risk. The mean total carcinogenic risk values for adults and minors were 0.501 and 0.210, respectively, falling within the ‘attention-required’ range. Depending on the exposure level, the risk to adults exceeded the safety threshold, and Al was the core driving factor. This study provides a scientific basis for targeted prevention, management, and remediation of regional groundwater pollution by heavy metals.