Source-oriented probabilistic human health risk assessments and priority heavy metal pollution control areas...

Investigation of heavy metals (HMs) in river basins is essential for formulating effective prevention and control strategies. This study presents a comprehensive investigation of ten HMs (Sb, V, Cr, Ni, Cu, Zn, As, Mo, Cd, Pb) in surface sediments of the Laoguan River basin, upstream of the Danjiangkou Reservoir. A total of 1386 sediment samples were collected and analyzed. Single-factor pollution index (P_i), Nemerow pollution index (P_N) and geo-accumulation index (I_geo) are employed to assess contamination levels. The potential ecological risk (RI) value of 676.30 indicates a high ecological risk, predominantly attributed to Sb and Cd. A source-based probabilistic health risk assessment is conducted by integrating positive matrix factorization (PMF), human health risk assessment (HHRA), Monte Carlo simulation (MCS). Children are subjected to higher health risk indices (HI) and total carcinogenic risks (TCR) than adults, with a 33.51% probability of exceeding the acceptable HI threshold. Sb-associated industries are identified as the dominant contributor to HI for children and TCR for all groups. Specifically, Sb and Cr are priority pollutants for HI, while As is the priority concern for TCR. A novel framework involving carcinogenic and non-carcinogenic risks, receptor vulnerability, and population distribution is established to identify priority control areas. Medium- and high-risk areas collectively account for 1.18% of the total area. This study provides a scientific basis for environmental management and health protection decisions in the watershed.