Quantitative Source Apportionment of Groundwater Contamination in the Poyang Lake Recharge Area: Insights from PMF and PCA-APCS-MLR Models

Quantitative source apportionment of groundwater contamination is essential for sustainable water resource management, yet the performance of receptor models in complex hydrogeological settings remains debated. This study employed Positive Matrix Factorization (PMF) and PCA-APCS-MLR (Principal Component Analysis–Absolute Principal Component Score–Multiple Linear Regression) models to analyze 16 hydrochemical parameters from 460 groundwater samples (collected at 339 sites), delineating pollution sources and characterizing the groundwater chemistry in the southern recharge zone of Poyang Lake, China’s largest freshwater lake. Both models consistently identified five primary pollution sources: mixed anthropogenic activities (contributing 13.6% and 8.6%, respectively), natural geological processes (28.9% and 45.6%), sewage discharge (23.5% and 24.4%), industrial effluents (13.3% and 12.1%), and agricultural practices (20.6% and 9.3%). Notably, heightened contamination was observed near industrial parks and urban centers through two models. The integrated analysis revealed that anthropogenic activities—particularly sewage discharge, agricultural practices, and industrial effluents—are the dominant drivers of groundwater quality deterioration. These human-induced inputs account for the vast majority of the pollution load (reaching up to ~71%), fundamentally altering the natural hydrochemical regime. Notably, elevated Mn2+ and NH4+-N concentrations are intricately linked to a combination of industrial effluents and legacy domestic sewage, which exacerbate the mobilization of natural background elements within the aquifer. These findings provide critical mechanistic insights into the complex interplay between human activities and groundwater hydrochemistry, demonstrating how dual-receptor modeling can unravel overlapping natural and anthropogenic inputs. Ultimately, this study offers a scientific basis for targeted pollution control and the sustainable management of global freshwater lake recharge zones.