ASSESSING SORPTION OF SHORT CHAIN PERFLUOROALKYL SUBSTANCES TO CARBONACEOUS MATTER IN SEDIMENT

Perfluoroalkyl substances (PFAS) are a group of emerging contaminants used in Aqueous Film Forming Foam (AFFF). Historically, long chain PFAS, having a carbon chain length of 8 or greater have been used in AFFF. After regulation of several long chain PFAS, including perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), it is expected that the detection of short chain PFAS (C<8) in groundwater will increase in the coming years as long chain PFAS have been phased out of AFFF formulas and replaced with their short chain counterparts. The fraction of organic carbon (foc) in sediment has been identified as an important factor controlling the sorption of long chain PFAS to sediment, but there is less of a consensus on the mechanisms important for the sorption of short chain PFAS. The goal of this research is to assess the relationship between sorption of short chain PFAS to sediment and the quality and quantity of carbonaceous matter (CM) in sediment. Initial batch experiments were conducted using PFOS, perfluorobutanesulfonic acid (PFBS), and shale from the former Naval Air Warfare Center in Trenton, New Jersey. Preliminary interpretation of the data suggests that sorption is greater in shale containing vials versus the ashed shale and sand control treatments which suggests that foc is an important determinant of sorption for PFBS, as well as PFOS. For sites contaminated with short chain PFAS, the foc of sediment will be a dominant factor for understanding fate and transport. Ongoing research is examining the behavior of additional PFAS, including perfluorohexanesulfonic acid (PFHxS) and will determine the relationship between sorption and organic matter maturity.