ReviewPerfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) in surface waters, sediments, soils and wastewater - A review on concentrations and distribution coefficients

The sorption of perfluorinated compounds (PFCs) to soils and sediments determines their fate and distribution in the environment, but there is little consensus regarding distribution coefficients that should be used for assessing the environmental fate of these compounds. Here we reviewed sorption coefficients for PFCs derived from laboratory experiments and compared these values with the gross distribution between the concentrations of PFCs in surface waters and sediments or between wastewater and sewage sludge. Sorption experiments with perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) suggest that their sorption can be described reasonably well as a partitioning-like process with an average log Koc of approximately 2.8 for PFOA and 3.0 for PFOS. However, median concentrations in sediments (PFOA, 0.27 ng g−1; PFOS, 0.54 ng g−1) or sewage sludge (PFOA, 37 ng g−1; PFOS, 69 ng g−1) in relation to median concentrations in surface water (PFOA, 3 ng l−1; PFOS, 3 ng l−1) or wastewater treatment effluent (PFOA, 24 ng l−1; PFOS, 11 ng l−1), suggest that effective log Koc distribution coefficients for the field situation may be close to 3.7 for PFOA and 4.2 for PFOS. Applying lab-based log Koc distribution coefficients can therefore result in a serious overestimation of PFC concentrations in water and in turn to an underestimation of the residence time of PFOA and PFOS in contaminated soils. Irrespective of the dissipation kinetics, the majority of PFOA and PFOS from contaminated soils will be transported to groundwater and surface water bodies.

► log Koc coefficients for PFOS and PFOA are similar for soils and sewage sludge. ► Field-based distribution coefficients are larger than lab-based coefficients. ► Dissipation times from soils may be underestimated using lab-based coefficients. ► Groundwater and surface waters are the main sinks for PFOA and PFOS.