Effect of industrial plants on adsorbable organofluorine concentrations in water and surface sediments of the Danube River in Hungary

The effect of industrial facilities, including Li-Ion Battery (LIB) manufacturing plants, a wrapping paper factory, and an oil refinery, along the Hungarian section of the Danube River, was assessed by measuring adsorbable organofluorine (AOF) concentrations in both water and surface sediment samples. Sediment samples exhibited similar grain size distributions (0.5-500 µm, peak around 100 µm) and mineral compositions (quartz 40–45%, mica 17–25%, and plagioclase-dolomite ~10%). AOF compounds were extracted using methanol and ultrasonic treatment, and concentrations were determined via granular activated carbon adsorption and combustion ion-chromatography. Mean AOF concentrations ranged from 0.17-19.7 μg/L in water and 98.8-602.9 μg/kg in sediments, with sediment enrichment attributed to biofilms on mineral grains, resulting in concentrations nearly two orders of magnitude higher than those in the water phase. Sediment total organic carbon (TOC) showed a strong positive correlation with AOF levels, especially near the wrapping paper factory (r=0.98), which predominantly uses long carbon chain PFAS, and a slightly weaker correlation (r=0.77) near LIB factories, where short carbon chain PFAS dominate. Lowest sediment AOF concentrations were observed near the oil refinery, coinciding with the highest TOC concentrations. Notably, flood events caused considerable redistribution of AOF in sediments, highlighting the dynamic influence of hydrological disturbances on PFAS transport. By comparing multiple industrial sources and accounting for hydrological variability, this study provides new insights into source-specific contributions and environmental fate of organofluorines in a major European river. These results underscore the potential of the sum-parameter AOF method for rapid and routine monitoring of industrial PFAS contamination in aquatic systems. • AOF conc. in surface sediments were ~2 orders of magnitude higher than in the water. • LIB and wrapping paper factories emitted comparable amounts of AOF compounds. • Flood considerably reduced the organofluorine content of surface sediments. • Low AOF and high TOC conc. were typical of surface sediments near oil refinery. • Strong positive AOF-TOC correlation existed near LIB and wrapping paper factories.