Temporal and spatial distribution of inorganic fluoride, total adsorbable organofluorine, PFOA and PFOS concentrations in the Hungarian section of the Danube River

The existing technologies in municipal wastewater treatment plants are ineffective in eliminating persistent fluorine-containing contaminants. At the same time, there is an increasing demand for novel organofluorine compounds, particularly in the production of lithium-ion batteries, as well as in the agrochemical and pharmaceutical sectors for more efficient ingredients. This implies that we must account for ongoing changes in the fluorine levels within riverine environments. To determine the fluorine concentration in the water phase of rivers, it is essential to measure both inorganic fluoride and total organofluorine concentrations. These analytes were measured in water samples collected monthly from twelve locations along the Hungarian section of the Danube River during the period from July to December 2023, applying ion-chromatography and combustion ion-chromatography. The concentration of inorganic fluoride ranged from 28 to 76 µg/L, with a median of 45.3 µg/L. The total adsorbable organofluorine concentrations were between 0.22 and 12.5 µg/L, with a median of 2.43 µg/L. To assess the impact of restrictions on the use of PFOA and PFOS compounds, these substances were quantified using a UHPLC-Q-TOF-MS system. A comparison of our data with previously published concentrations in the Danube River reveals a decreasing tendency, justifying the restricted use of these chemicals. [Display omitted] •Inorganic fluoride, organofluorine, PFOA and PFOS were quantified in Danube River.•Median concentration of fluoride was order of magnitude higher than organofluorine.•Tributaries, industrial factories had only slight influence on spatial distribution.•Temporal distribution of organofluorines harmonized with their increased washout.•Restricted use of PFOA and PFOS is well reflected by their decreasing concentrations.