Risk Assessment and Source Analysis of Heavy Metals in Soil around Nansihu Lake Based on APCS-MLR and PMF Models

Heavy metal pollution in the Nansihu area was evaluated using the geo-accumulation index, pollution load index, and potential ecological risk assessment, with source analysis performed through the absolute principal component-multiple linear regression (APCS-MLR) model and positive definite matrix factorization (PMF) model. The average concentrations of As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn were below standardized background values; however, Hg exhibited significant enrichment, with an average concentration 1.37 times higher than the Jining City soil background, indicating localized point-source pollution driven by anthropogenic activities. Source analysis identified four major contributors: agricultural, natural, transportation, and industrial sources. The APCS-MLR model attributed 34.63%, 29.17%, 25.81%, and 10.39% of the pollution to agricultural, natural, transportation, and industrial sources, respectively, while the PMF model assigned 22.93%, 30.46%, 25.13%, and 21.48%. These results highlight the distinct roles of human activities in heavy metal contamination, particularly Hg, and demonstrate the value of integrating APCS-MLR and PMF models for comprehensive source apportionment and environmental management strategies.