Concentration Characteristics, Source Apportionment, and Health Risk Assessment of Groundwater Contaminants in a Karst Coal Mining Area (Guizhou Province, China)

Abstract

The contamination of groundwater in karst coal mining areas presents a unique environmental challenge due to the interplay between fragile hydrogeology and intensive anthropogenic activity. This study investigated the concentrations, sources, and health risks of characteristic contaminants in groundwater from a karst coal mining area, aiming to provide a scientific basis for groundwater pollution control. Thirty-two groundwater samples were analyzed for nine target contaminants. Principal component analysis (PCA) and a health risk assessment model were integrated to identify pollution sources and evaluate health risks. Results showed that the concentrations of Fe, Mn, Fluoride, Pb, and Sulfate exceeded the Class III limits of the “Standard for Groundwater Quality” (GB/T 14848-2017), with maximum exceedance multiples of 3.60, 1.51, 1.08, and 1.22 times the standard limits, respectively. The maximum concentrations of Mn, Fluoride, and Pb exceeded the WHO guidelines by factors of 4.75, 0.67, and 1.00, respectively. Furthermore, the Pb concentration also surpassed the USEPA standard by a factor of 0.33. PCA identified three principal components, which together explained 71.065% of the total variance and were attributed to mining activities (PC1), mixed natural and anthropogenic sources (PC2), and natural geological processes (PC3), respectively. The health risk assessment reveals significant risks: arsenic poses a carcinogenic risk (CR > 10−4), while both arsenic and Fluoride contribute to non-carcinogenic risks (HI > 1). The cumulative exposure from these contaminants demands immediate attention.