IDENTIFYING EFFECTIVE FARMING PRACTICES TO REDUCE RISKS OF PER- AND POLYFLUOROALKYL SUBSTANCES (PFAS) IN FOOD CROP PRODUCTIONS

The overall goal of the proposed study is to increase our understanding of the distribution and transport of per- and polyfluoroalkyl substances (PFAS) in agroecosystems, and to further identify the best management practices for reducing their risks on food production if recycled municipal wastewater (or reclaimed water) is used for irrigation, e.g., semi-arid regions. The proposed work addresses two important food safety questions related to the fate and transport of contaminant of emerging concerns (CEC) when reclaimed water is used as a source water for irrigation.Q1. What are the environmental factors and farming practices controlling the distribution and transport of PFAS in agricultural ecosystems? Q2.Could we mitigate the impacts of PFAS in reclaimed water through effective irrigation and soil amendment practices?Due to an increasing demand on freshwater supply, recycled or treated municipal wastewater have been considered an alternative source water for agricultural irrigation, especially in highly populated and/or semi-arid regions. However, significant levels of PFAS often found in municipal wastewaters have raised a health concern if these reclaimed waters are used for agricultural food production. A number of studies have already observed that crops and plants could take up PFAS from reclaimed waters. Until now, the application of biosolids has been widely studied as the main pathway for the introduction of PFAS into soil . Despite the existence of PFAS in reclaimed water, there has been no study examining their distribution and remediation in agroecosystems under field environmental factors when using reclaimed water for irrigation. Importantly, the occurrence of earthworms can adsorb hydrophobic PFAS, resulting in the change of their distribution and increase of their chemical persistence in the environment for a long time. We thus hypothesize that field environmental factors affect the distribution and transport of PFAS greatly and the in-situ strategies of irrigation methods and soil amendment are affordable and efficient for risk reduction in agricultural ecosystems using reclaimed water for irrigation.Obj 1 - Occurrence and distribution of PFAS in agricultural ecosystems - Distribution of short and long chain PFAS is different across agricultural ecosystems, depending on soil properties, soil organic matter content, soil microbiomes (i.e., earthworms), and farming practices.Obj 2a -Risk Reduction through Irrigation strategies - The fate and transport of PFAS depends on water movement, which is mainly controlled by irrigation methods. Selecting an optimal irrigation method for a special crop species under field conditions is a strategy for reducing the PFAS risks by treated wastewater irrigation.Obj 2b- Risk Reduction through soil amendment strategies - Soil amendments adsorbs PFAS on their surface, resulting in the reduction of their concentration and bioavailability in agricultural soils. Sub-surface irrigation coupled with soil amendments around laterals is a great strategy for reducing the introduction of PFAS from treated wastewater.