Characterization and source apportionment of heavy metal contamination in agricultural soils in the complex genesis region of western Yunnan

The genesis of heavy metal contamination in arable soils is complex, and scientifically identifying risks and precisely analyzing contamination sources are essential for safely using contaminated arable land. In this study, we systematically evaluated the pollution characteristics of Cu, Zn, As, Hg, Cd, Pb, Ni, and Cr in soil, and then applied the APCS-MLR and PMF models to jointly analyze pollution sources and their contributions. The results showed that the concentrations of the eight heavy metals were significantly higher than the background values for soils in Yunnan Province, exhibiting clear spatial heterogeneity. The overall pollution level ranged from mild to severe, with Cd and Pb being the most critical contaminants. Four major pollution sources (industrial transportation, parent material, agriculture, and mining) were identified through the dual modeling approach. The results of both models corroborated each other, and the accuracy of the analysis was significantly improved compared to using a single method. This study not only provides a scientific basis for the safe utilization of contaminated arable land in western Yunnan, an area with a complex genesis of soil contamination, but also offers a generalized framework for source analysis in areas affected by geological-anthropogenic composite pollution.