From flood peaks to drinking-water wells: River-level dynamics and the transport of PFAS during riverbank filtration along the Danube
Drinking-water supply along the Danube depends heavily on riverbank filtration (RBF), yet recent monitoring shows that per- and polyfluoroalkyl substances (PFAS) move through the subsurface largely unattenuated. In this seminar, I will present an overview of Ali Obeid’s PhD work, combining a one-year monitoring campaign at four RBF transects in Vienna and Budapest, column experiments on PFAS transport in saturated porous media, and 3D reactive transport modelling.
The central question is how river-level fluctuations and flood events govern infiltration, travel times and the mixing of bank filtrate with ambient groundwater — and therefore how, when and where PFAS reach the production wells. Field observations show that most PFAS pass from the Danube into the adjacent aquifer with little concentration reduction, while two Budapest sites reveal inland PFAS sources (PFOA, PFOS, GenX) that emerge most clearly under specific hydrological conditions.
I will then briefly present Ali’s saturated soil column experiments with a mixture of ten PFAS, which reveal four distinct sorption-type categories ranging from near-conservative transport to nearly complete retention, with sorption controlled by molecular descriptors beyond chain length and significant desorption during extended flushing. I will conclude with implications for setback distances and protection zones under upcoming EU regulatory limits.
Based on Obeid et al. (2023) and ongoing PhD work · A. Obeid, T. Oudega, O. Zoboli, M. Zessner, J. Derx
