Pollution Characteristics, Sources, and Risk Assessment of Potentially Toxic Elements in the Soil–Leaf System of an Industrial Park

Industrial parks are hotspots of potentially toxic element (PTE) pollution, yet single-medium assessments fail to capture atmospheric contamination and source-specific risks. This study integrated soil–leaf analysis with quantitative source apportionment to evaluate PTE pollution in a chemical industrial park in China’s lower Yangtze River region. Soil and Photinia serratifolia leaf samples from 31 sites were analyzed for eight PTEs using the Pollution Load Index (PLI), Enrichment Factor (EF), Bioconcentration Factor (BCF), and Foliar Capture Rate (FCR). Principal Component Analysis–Multiple Linear Regression quantified source contributions to concentrations and risks. Results revealed moderate soil contamination (PLI = 1.43) with localized enrichment of As, Cd, Cu, and Zn (EF > 5). Element-specific pathways differed markedly: Cd, Zn, and Cu showed patterns consistent with relatively greater soil-related uptake contributions (BCF = 0.85–1.12; FCR < 25%), whereas As, Cr, Ni, and Pb exhibited patterns suggestive of stronger atmospheric deposition influences (BCF < 0.5; FCR = 54–78%). Four sources were identified, with chemical manufacturing contributing 53% of the ecological risk and 55% of the carcinogenic risk and thermal power generation accounting for 67% of the non-carcinogenic risk. Ecological risk was low (Risk Index = 113) and non-carcinogenic risk was negligible (Hazard Index = 0.0646), but carcinogenic risk was non-negligible (Carcinogenic Risk = 1.43 × 10−5). This study demonstrates that foliar bioindicators can provide indicative evidence of atmospheric contamination and that source contributions to risk differ substantially from mass contributions, providing a methodological framework for targeted pollution control.