Precursors, Novel and Ultrashort PFAS in Soils and Leachates

PFAS is a group of contaminants for which the picture is complex in terms of occurrence, composition, tools for risk assessment and remedial actions. In this work a comprehensive characterization of PFAS in five AFFF polluted soils was performed. This included known “regular” PFAS (34), a range of “novel” PFAS e.g. ethers, sulphonamides (SA), ultrashort and the known AFFF constituent 6:2 FTAB. TOPA (including ultrashort) was used as a tool for determining precursors and gain information on their (basic) structures. Leaching tests (EN12457-2; L/S=10) were carried out; novel and PFAS34 were determined in leachates before TOPA and PFAS34 after. The pattern of formed PFCA and branched/linear (Br/L) isomers before/after TOPA were evaluated to distinguish between ECF vs fluorotelomerization (FT) production. Results showed that the PFAS composition reflected AFFF used and was mirrored in both soils and leachates. Regular PFAS34 made up <5-100% in soil/leachate of the sum after TOPA, a fraction not possible to assess on beforehand. Formation of ultrashort PFAS, especially PFPrA after TOPA was highly significant corresponding to 23-47% on a molar basis. 6:2 FTAB was found in all soils and was the dominant PFAS in two. Patterns of PFCA formed indicated origin of the precursors, primarily 6:2 but also 8:2 FT based. Br forms suggested minor contributions of C6/C8 SAs. Measured precursors, in particular 6:2 FTAB could explain some of total PFCA formed but the major part remained unknown.

We will conclude the session with audience driven questions and answers. Please email me at elearning@landandgroundwater.com with any detailed aspects of the subject you would like addressed.

Patrick van Hees works at Eurofins Environment in Sweden with business development and technical support, and is also a part-time senior adjunct lecturer at Örebro University (SE). Patrick is an Assoc Prof in the field of analytical soil chemistry, and research has concerned clean-up of contaminated soil as well as more basic soil processes. Besides Sweden, Patrick has also worked at universities in the UK and Japan. Current interests include analytical development for soil, waste and other environmental matrices, both inorganic and organic compounds. Patrick is also the company’s representative at the Swedish Standards Institute (SIS) since 13 years.