Rhizosphere horizons are particularly susceptive to heavy metals and organic contamination, including per- and polyfluoroalkyl substances (PFAS), due to their specific biogeochemical processes. The main objective of this project is to evaluate the distribution of PFAS in plants exposed to mixed contaminants, and their effect in the rhizosphere and in planta microbial community, to provide a comprehensive understanding of the mechanisms controlling PFAS effect on plant growth and microbial community changes. Field measurements are combined with hydroponic experiments using the model plant Arabidopsis thaliana and in vitro experiments with Poa reptans to assess the mechanisms of PFAS plant translocation, microbiome changes, and toxicity. This work focuses on the Ringwood/Ford Superfund, NJ site where lead, arsenic, chloroethane, benzene and 1,4-dioxane are the main contaminants of concern. However, PFAS have been measured in surface water downstream a paint sludge disposal area (PFOS 445 ng/L, PFOA 23.78 ng/L, PFNA 25.69 ng/L, sediments (PFOS 2.18 ng/g), rhizosphere (PFOS 2.45 ng/g) and plants (PFOS 0.811 ng/g roots). Hydroponic investigation on PFAS uptake by Arabidopsis thaliana shows PFOA preferred accumulation in shoots and PFOS preferred accumulation in roots, and a direct relationship with PFAS solution concentration. The changes in microbial communities are being evaluated using next-generation DNA Illumina sequencing. In vitro laboratory experiments showed that endophytic microbial community decreased PFAS toxicity to Poa reptans seedlings. PFAS exposure resulted in damage to the root hairs and lack of internal cyclosis only in the absence of bacteria seedlings. Further, the presence of microorganisms seem to prevent PFAS uptake by exposed seedlings. This work is expected to provide a holistic understanding of the fate and transformation of PFAS within the various environmental compartments, it will inform future remediation strategies and exposure prevention alternatives.

PFAS distribution in contaminated soils and impact on rhizosphere and plant microbiota

ACS Spring Meeting 2021

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