Occurrence, Spatial Distribution, and Risk Assessment of PFOA and PFOS in the Henan Section of the Yellow River

To address the environmental evolution and management needs of emerging contaminants in the Yellow River Basin (Henan Section), China, nine typical functional cross-sections, covering industrial outfalls, sewage treatment plant (STP) effluents, human activity-dense areas, and baseline tributaries, were selected to systematically investigate the occurrence, potential sources, and multi-dimensional risks of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) in surface water. The results indicated a 100% detection rate of the target pollutants across all sites, with PFOA (0.45-7.46 ng/L) being the absolute dominant analogue. The spatial distribution exhibited an evident industrial point-source-driven pattern, where the pollution loads at the Jili District industrial outfall (S7) and STP effluent (S5) were significantly higher than those in non-point sources and natural baseline waters. Source apportionment suggested that direct wastewater discharge and secondary release from regional industrial clusters were likely key contributors to PFAS spatial heterogeneity. Multi-dimensional risk assessments revealed that the current ecological risk quotients (RQ < 0.01) for aquatic organisms and the human health risk values (HR < 0.1) via drinking water ingestion for various age groups were well within safe and controllable ranges. However, PFOS contributed significantly more to the ecological risk than PFOA, and children exhibited slightly higher health exposure vulnerability than adults. Although the overall risk is minimal, PFOA concentrations at high-load cross-sections have exceeded the latest stringent maximum contaminant level (4.0 ng/L) mandated by the US EPA in 2024. This study suggests an urgent need to establish a dynamic, life-cycle monitoring network for PFASs in the basin and to prioritize targeted deep-reduction strategies for high-risk industrial point sources.