Enhanced Extraction of AFFF-Associated PFASs from Source Zone Soils

Area of Science:

• Environmental Chemistry
• Contaminant Hydrology
• Analytical Chemistry

Background:

• Poly- and perfluoroalkyl substances (PFASs) from aqueous film-forming foam (AFFF) are significant groundwater contaminants.
• Existing analytical methods often fail to fully extract zwitterionic and cationic PFASs from soils and sediments.
• Understanding the full PFAS composition in AFFF-impacted soils is critical for effective remediation.

Purpose of the Study:

• To develop and validate a sequential extraction method for recovering anionic, cationic, and zwitterionic PFASs from AFFF-impacted soils.
• To assess the contribution of various PFAS types to total contamination in soil.
• To highlight the necessity of comprehensive analytical approaches for AFFF-derived PFASs.

Main Methods:

• Sequential basic and acidic methanol extractions were employed for PFAS recovery.
• Method validation was performed using spike-recovery experiments with soil-water-AFFF mixtures and analytical standards.
• A novel semiquantitation approach was used for PFASs lacking commercial standards, with results compared to the total oxidizable precursor assay.

Main Results:

• The developed method successfully recovered anionic, cationic, and zwitterionic PFASs from field-collected soils.
• In soil cores from former fire-training areas, cationic and zwitterionic PFASs constituted up to 97% of the total PFAS mass.
• Semiquantitation provided estimates for PFASs without commercial standards, aiding in a more complete mass balance.

Conclusions:

• The study demonstrates the significant contribution of cationic and zwitterionic PFASs to AFFF-impacted soil contamination.
• The developed extraction and analytical method is essential for accurately quantifying these previously underrepresented PFASs.
• Comprehensive analysis is required to fully understand and manage PFAS contamination originating from AFFF.