Characterizing PFAS Enrichment in Naturally Occurring Surface Water Foams

Polyfluoroalkyl Substances (PFAS) in the Environment
Oral Presentation

Prepared by
Eurofins Lancaster Laboratories Environmental, 2425 New Holland Pike, Lancaster, PA, 17601, United States


Contact Information: schwicht@oregonstate.edu; 507-456-2829


ABSTRACT

Foaming surface waters near sites where aqueous film forming foams (AFFFs) and other sources of per- and polyfluoroalkyl substances (PFAS) were released have raised public concern. Accumulation of PFAS at the air-water interface is due to their surface active nature, yet few measurements of PFAS in foam are reported. Foam arises upon agitation of the surface microlayer of surface water bodies (e.g., wind action) that may be enriched in surface active PFAS. After a foaming event in 2018, pairs of foam and the bulk water immediately under the foam were collected. Samples were analyzed by liquid chromatography quadrupole time of flight mass spectrometry for 50 target and >1400 suspect individual PFAS and 12 suspect classes of hydrocarbon surfactants. Concentrations in foam and underlying bulk water were ratioed to generate an enrichment factor for PFAS and hydrocarbon surfactants in each pair of samples. Foams were enriched in long-chain PFAS, including PFNA, PFDA, and PFUnDA, and hydrocarbon surfactants such as linear alkylbenzene sulfonate relative to bulk water. These long-chain PFAS were near detection levels (ng/L) in bulk surface water but were in the µg/L level in foam (when collapsed to a liquid). Analytical challenges regarding the handling of the foam matrix will be discussed.