PFAS: Sources and Source Identification

Regulatory activity related to per- and poly-fluoroalkyl substances (PFAS) has increased substantially in the last several years. PFAS are persistent and widespread in the environment due to usage in myriad industries and products, low degradation and sorption rates, and low environmental regulatory standards (in the parts per trillion range). However, PFAS differ from other recalcitrant contaminants in that the term encompasses thousands of chemicals, many of which degrade to one of dozens of “terminal compounds” (such as PFOS and PFOA) that are the focus of recent regulatory attention. Recognized PFAS sources include fire-fighting foams, industrial and manufacturing facilities (e.g., electronics, semi-conductors, metal plating), oil and gas production, pesticides/herbicides, and mining. PFAS are present in ski wax, and studies have even indicated PFAS impacts in ski-area snowmelt. Due to the use of PFAS in consumer products, PFAS sources also include landfills, wastewater treatment discharge, biosolids associated with wastewater treatment, and septic systems. This talk will present the relative concentration of PFAS in each of these various sources and the “fingerprint” associated with each (i.e., the relative contribution of various perfluorocarboxylates, perfluorosulfantes, and PFAS precursors). The presence of PFAS from so many potential sources must be accounted for in site investigations, and this talk will explore forensic techniques used to differentiate releases from different sources including one case-study example. In addition, the talk will compare the extent of PFAS occurrence in soils, sediments and groundwater from an environmental release as compared to potential co-contaminants as impacted by contaminant transport processes including interfacial partitioning.