[Source Apportionment and Ecological Risk Assessment of Soil Heavy Metals in the Mohe River Basin Based on...

The spatial differentiation and driving mechanisms of multi-source heavy metal pollution at the watershed scale represent a core scientific challenge for ecological risk management in mining areas. Focusing on the mining-agriculture coupled system in the Yellow River Basin (Mohe River Basin, Henan Province), this study integrated the positive matrix factorization (PMF) model, potential ecological risk index (RI), and Geodetector method to systematically reveal the spatial heterogeneity of soil heavy metal pollution, ecological risk patterns, and driving mechanisms in open-pit mining areas. The results demonstrated that: ① Heavy metal pollution exhibited a significant gradient distribution, with contributions from traffic emissions (28.5%), mining activities (27.1%), agricultural non-point sources (24.3%), and natural sources (20.1%) decreasing sequentially. The spatial differentiation characteristics were strongly correlated with land use types and industrial layout. ② Cd and As contributed over 50% to the comprehensive ecological risk due to their high biotoxicity, driving the concentration of 12.3% high-risk zones along the mining-agriculture transitional belt. The intensity of their ecological risk showed a significant negative correlation with soil pH and organic matter content. ③ GeoDetector quantification identified elevation (q=0.42), population density (q=0.35), and distance from mines (q=0.21) as the core driving factors. Their interactions exhibited nonlinear enhancement, dominating the spatial differentiation of risks, which indicates a synergistic amplification effect between natural geographical mutation interfaces and anthropogenic disturbances.