Plant uptake and soil fractionation of five ether-PFAS in plant-soil systems

Considering the grave concerns caused by conventional per- and polyfluorinated substances (PFAS), production and use of fluoroalkylether compounds (ether-PFAS) have been on the rise. These ether-PFAS are deemed as PFAS replacement chemicals. To understand distribution of ether-PFAS in plant-soil systems, we investigated plant uptake of five selected ether-PFAS (i.e., PFMOPrA, PFMOBA, GenX, ADONA, F53B) by Carex comosa (longhair sedge) and the fractionation of these compounds in soil. Our results demonstrated that all five ether-PFAS in this study were taken up by C. comosa and translocated to plant shoots to different extents. Exposure concentration and time both positively affected plant uptake of ether-PFAS. Unlike the other four ether-PFAS, F53B with the longest carbon chain length and a sulfonic functional group was largely accumulated in C. comosa roots with limited translocation to plant shoots. Results from sequential extractions revealed that the five ether-PFAS had different distributions in soil with regard to extractable by water, basic methanol, acidic methanol and non-extractable. Concentration of ether-PFAS in water-soluble fraction increased with decreasing carbon chain length and logK_ow values and had a positive linear relationship with the mass of ether-PFAS in plant shoots (R² = 0.64) and in whole plants (R² = 0.94). Our results also indicated that the aging process could facilitate ether-PFAS to become non-extractable, hence reducing their mobility in soil and bioavailability to plants.