Long-term leaching of PFAS from contaminated agricultural soils in Germany

By Röhler, Klaus, Alexander Arthur Haluska, Bernd Susset, Binlong Liu, and Peter Grathwohl
J. Contam. Hydrol.
April 19, 2021
DOI: 10.1016/j.jconhyd.2021.103812

Contamination of soils and groundwater aquifers by per- and polyfluoroalkyl substances (PFAS) has become a highly documented problem worldwide. To assess the long-term behavior of PFAS in soils and groundwater and to develop remediation strategies, a better understanding of leaching and mobility of PFAS in soils and groundwater is needed. Many PFAS contaminated sites have been identified over the last decade in Germany, most prominent is currently agricultural land where PFAS contaminated compost material has been applied over the last few decades, resulting in large-scale contamination of soil and groundwater. The specific objectives of this study are to assess the longevity of the PFAS agricultural sources and to compare standardized column percolation tests to long-term leaching of PFAS from contaminated sites. Column leaching tests conducted with PFAS contaminated soil simulated the rapid initial decline but failed to predict the long-term behavior (tailing) observed at the field site over 12 years. Perfluorooctanoic acid (PFOA) leaches more rapidly than perfluorooctane sulfonic acid (PFOS) and topsoils have a higher retention capacity for these compounds than deeper soil horizons as a function of the organic carbon content. Mass balances indicate that leaching time scales of these compounds may amount to many years to decades. Analysis of field data over a time period of 12 years revealed no or slowly decreasing trends as well as seasonal fluctuations, likely due to ongoing transformation of precursors and a seasonal influence on production rates of mobile PFAS.

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