High-Resolution Source Apportionment and Spatiotemporal Drivers of Per- and Polyfluoroalkyl Substances (PFAS) Across China’s Largest River-Estuary Continuum: Toward Sustainable Management of Emerging Contaminants

Abstract

This study developed and applied a multivariate framework to identify and prioritize key sources and socioeconomic drivers of per- and polyfluoroalkyl substances (PFAS) pollution along the 600-km long Yangtze River downstream to the Estuary continuum. A total of 180 samples, including water, suspended particulate matter (SPM) and sediment, were systematically collected from different river segments, wastewater effluents and drinking water sources along the river. Perfluorobutanoic acid (PFBA) was the dominant PFAS across all matrices, followed by perfluorohexanoic acid (PFHxA) and perfluorodecanoic acid (PFDA). SPM-water partitioning was primarily influenced by compound-specific carbon chain length and salinity gradients. Source apportionment using self-organizing map, geographically weighted regression, and distance-decay analysis identified a riverside fluorochemical manufacturing facility as a primary point source, along with five secondary fluorine-related sources. Structural equation modeling revealed that industrial development had a stronger direct impact on PFAS contamination (path coefficient = 1.637, P < 0.01) than urbanization (path coefficient = 0.347, P < 0.01). Based on socioeconomic indicators, random forest and support vector machine models were employed to project PFAS concentrations from 2015 to 2035 under a rapid urbanization scenario. The average sedimentation rate of Σ₁₂PFAS was estimated at 168 pg/g·y^-1, with projected stabilization after 2025 likely driven by the implementation of new pollutants control policies. These findings provide a practical basis for source-targeted PFAS management in complex estuarine environments.