Contamination of heavy metal(loid)s in groundwater around mining and smelting area: quantitative source-oriented...

The accumulation of heavy metal(loid)s (HMs) in groundwater from mining and smelting industries threatens ecological systems and public health, yet quantitative source-oriented health risks to surrounding residents remain underexplored. This study investigated the pollution characteristics, spatial distribution, source apportionment, and associated health risks of HMs in groundwater at a typical mining-smelting site in China. Sixteen villages near the industrial complex were designated as the exposure area, while three villages 30 km away served as the control area. Fourteen HMs (Mn, Fe, Cu, Zn, Mo, As, Cd, Pb, Sb, V, Cr, Co, Ni, Tl) were detected in the exposure area's groundwater, with a total HM (ΣHMs) mean concentration of 74.07 μg/L-significantly higher than the control area's 37.08 μg/L. Essential HMs (EHMs) dominated the composition, with Zn and Fe as the most abundant elements, whereas non-essential HMs (NEHMs) like Cr and Pb exceeded drinking water standards set by the World Health Organization (WHO) and U.S. Environmental Protection Agency (U.S. EPA). Spatial distribution showed high HM contamination at sites adjacent to the smelting plant. Principal components analysis (PCA) and positive matrix factorization (PMF) models identified mining (34.0%) and smelting (41.3%) as major sources of HMs. Probabilistic health risk assessment via Monte Carlo simulation revealed that 17.9% of adult and 24.7% of child carcinogenic risks in the exposure area exceeded the definite risk threshold value of 10^-4, primarily driven by As and Cr ingestion. Source-oriented health risks were assessed by integrating PMF source apportionment into risk model to evaluate the HM risks from identified sources. Results revealed that smelting activities contributed 43.5% (adults) and 43.6% (children) of total carcinogenic risks, while mining accounted for 36.0% in both populations. These findings highlight smelting operations as the primary driver of groundwater HM contamination and emphasize the need for targeted groundwater remediation to mitigate health risks from industrial activities.