Fate of per- and poly-fluoroalkyl Substances (PFASs) in soils affected by plant and rhizosphere microbial community

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Per- and polyfluoroalkyl substances (PFAS) represent a class of over 3,000 synthetic compounds that have been widely used in industry. PFASs are increasingly detected in humans, drinking water, soils, plants, and wildlife. These findings have raised significant concern because PFASs are persistent thus accumulate in the environment. PFAS have been implicated in increased cancer rates, interference with cholesterol metabolism, and disruption of endocrine function in humans. A major environmental source of PFASs are aqueous film-forming foams (AFFFs) released during fire-fighting events and training exercises. Once AFFFs are released to soils, PFAS can be taken up and potentially transformed by microorganisms in the soil. While this can lead to removal of PFAS from soil, much is not known about the fate of PFAS in the rhizosphere environment (i.e., the soil around plant roots). Primary among these is the question whether plants, soil microbes, or both are responsible for the biodegradation. The focus of this project is to answer these questions and identify which factors control the transformation processes. Better understanding of the mechanisms controlling the fate of PFAS in soils will enable the development of cost-effective remediation technologies for PFAS-contaminated soils. Results from this work will form the basis of an educational outreach program focused on under-represented groups to increase the diversity of the Nation's STEM workforce.The goal of this study is to identify key factors affecting the fate of per- and polyfluoroalkyl substances (PFAS) in soils for the development of effective strategies to mitigate risks of PFAS soil contamination. The focus of the proposed study is to delineate the roles of soil microbes, plants and their root exudates, and the synergic interactions between plants and soil microbes on the fate of PFAS in soils. The specific research objectives are to: i) determine the role of soil microbiota in PFAS biotransformation in AFFF-impacted soils; ii) investigate the reciprocal impacts of root exudates on the fate of PFAS in soils; and iii) examine the potential effects of plant/bacterial synergisms in PFAS biotransformation in soils. The results of the proposed study will advance fundamental knowledge on the underlying mechanism mediating PFAS biotransformation by both rhizosphere and non-rhizosphere associated microbes. This research will provide insight into effective phytoremediation strategies for mitigating PFAS contamination in soils. An effective treatment strategy that integrates knowledge of both plants and their associated microbial communities would be a scientific breakthrough, leading to the reduction of PFAS and their potential precursors from the environment. The proposed research serves as a fertile ground for interdisciplinary training of graduate and undergraduate students at the interface of microbiology, plant science, and environmental engineering. Broader impacts will result from the engagement and outreach to under-represented groups, dissemination of research results to the scientific community, and from presentations at local, national and/or international conferences.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.