Europe-wide estuarine export and surface water concentrations of PFOS and PFOA.

The STREAM-EU model was used to predict the water concentrations, estuarine export and retention of perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) in the eleven most populated European river catchments to provide a European-wide perspective on the contamination by these substances. Emissions of PFOS and PFOA to those catchments were calculated based on population, wealth and wastewater treatment plant (WWTP) coverage and efficiency using a previously published method and used as model input. Our estimated emissions showed the lowest values for the Thames catchment (PFOS: 0.4 ton/y; PFOA: 0.2 ton/y) and the highest values for the Rhine for PFOS (1.6 ton/y) and for the Dnieper for PFOA (1.7 ton/y). The model predicted concentrations agreed reasonable well with the existing range of measurements, apart from for PFOA in the River Po, where there is a known historical industrial contamination, and PFOS in the Rhone River, where results were much higher than the few measurements available. It was concerning that the model predicted that the surface water EQS for PFOS (0.65 ng/L) was exceeded by a wide margin in all the eleven studied European river catchments. The total calculated riverine export to the seas from the eleven catchments was 4.5 ton/y of PFOS and 3.7 ton/y of PFOA with highest exported quantities from the Rhine (PFOS: 1.0 ton/y; PFOA: 1.0 ton/y) and Danube estuaries (PFOS: 0.9 ton/y; PFOA: 0.7 ton/y). For the seas where the rivers discharge, riverine discharge of PFOS was estimated to be 2.5-30 times more important as an input than atmospheric deposition, whereas for PFOA the opposite was true (atmospheric deposition was 2-10 times more important) except for very small seas.