Laboratory optical measurements in support of assessing PFAS enrichment in natural foams on surface waters within the Delaware River Basin

One phenomenon that has been shown to concentrate and release per- and polyfluoroalkyl substances (PFAS) in surface water is the formation of natural foams. For surface water foams to form, surface active compounds or surfactants must be present in the water along with a source of gas bubbles. Some examples of surface-active compounds include humic and fulvic acids, colloidal particles, and lipids and proteins. The relationship between PFAS and dissolved organic matter (DOM) is important because studies have shown that DOM can affect PFAS fate and bioavailability in aquatic systems and treatment processes. The results from this assessment will improve our understanding of PFAS fate and transport in the environment. Surface water and foam samples were collected from two sub-basins in the Delaware River Basin to compare PFAS, PFAS total oxidizable precursors (TOP), and DOM concentrations and composition in surface water foams to that of underlying bulk water, upstream water, and downstream water. Data were collected in support of the U.S. Geological Survey (USGS) Water Mission Area Integrated Water Availability Assessments program in coordination with the Pennsylvania Department of Environmental Protection (PADEP) and USGS Water Science Centers in Pennsylvania and California.