Polyfluorinated compounds (aka “precursors”) are a large group of organic compounds present in aqueous film-forming foams (AFFFs) that were used to extinguish hydrocarbon fires. Previous work using high-resolution mass spectrometry has confirmed the frequent occurrence and high concentrations of precursors within soil and groundwater at AFFF-impacted sites. Recent studies have confirmed in situ abiotic and biotic degradation of precursors in the soil environment; however, the mechanisms of many aspects of precursor abiotic and microbiological transformation still remain elusive. A clear understanding of the in situ precursor biotransformation in the subsurface depends on an understanding of the mechanisms by which genes encoding their metabolism are spread throughout a soil community. To address these knowledge gaps, this proof-of-concept project will pursue the following objectives: (1) identify, characterize, and quantify key abiotic and microbiological processes controlling the transformation and degradation of AFFF-relevant precursors; and (2) develop molecular biological tools (MBTs) to characterize and quantify in situ microbiological transformation and degradation of precursors under ambient field conditions.

This project will identify the major abiotic and microbiological processes and pathways capable of transforming AFFF-relevant precursors. Key biomarkers, state-of-the-art biological tools, and algorithms will be identified and developed to understand the microbiological transformation of precursors. Abiotic and biotic transformation products of precursors will be identified by quadrupole time-of-flight mass spectrometry; an open library with all transformation products will be developed and shared with the scientific community. Lastly, this project will investigate the relationship between biomarker measurements and in situ precursor transformation.

This project will generate new data that will serve to advance the understanding of the environmental fate of precursors. Private and public sector communities will benefit directly or indirectly from the outcomes from this project, which include:

• novel MTB tools for characterizing the abiotic and biotic degradation behaviors of precursors in the soil environment;
• improved predictability of precursors’ fate in the subsurface at AFFF-impacted sites;
• a more thorough understanding of microbial community population, structure, diversity, and transfer of genetic information as it applies to precursor transformation in the field;
• an initial assessment of the persistence, occurrence and mobility of precursors and the potential for impacting microbial communities; and
• recommendations for precursor use, application methods, and region-, and site-specific management practices to minimize environmental contamination caused from precursors.

(Anticipated Project Completion - 2024)