Evaluation and Source Apportionment of Potentially Toxic Elements in the Chayuan Reservoir, Guizhou Province Using the Potential Ecological Risk Index (RI) and the PMF Model

< 0.01). Although the overall ecological risk was low (RI = 83.15-106.69), As contributed the highest proportion of risk (28-35%). PCA indicated distinct grouping patterns among elements, while PMF resolved three major sources: domestic sewage and agricultural runoff, agricultural and coal-combustion inputs, and industrial-traffic emissions. Notably, physicochemical parameters (TP, TN, and COD) played important roles in regulating the mobility and partitioning of PTEs by influencing nutrient-associated adsorption processes, organic matter complexation, and redox-related transformations. These findings highlight the multi-source-driven accumulation mechanisms of PTEs in karst reservoirs and provide a scientific basis for targeted pollution control and watershed management in agriculturally impacted regions.