Degradation and Plant Transfer Rates of Seven Fluorotelomer Precursors to Perfluoroalkyl Acids and F-53B in a Soil-Plant System with Maize (Zea mays L.)

Abstract

Fluorotelomer precursors in soil constitute a reservoir for perfluoroalkyl acids (PFAAs) in the environment. In the present study, precursor degradation and transfer rates of seven fluorotelomer precursors and F-53B (chlorinated polyfluoroalkyl ether sulfonates) were investigated in pot experiments with maize plants (Zea mays L.). The degradation of fluorotelomer precursors to perfluoroalkyl carboxylic acids (PFCAs) and their uptake spectra corresponded to those of fluorotelomer alcohol (FTOH) in terms of the number of perfluorinated carbon atoms. Short-chain PFCAs were translocated into the shoots (in descending order perfluoropentanoic, perfluorobutanoic, and perfluorohexanoic acid), whereas long-chain PFCAs mainly remained in the soil. In particular, fluorotelomer phosphate diesters (diPAPs) were retained in the soil and showed the highest degradation potential including evidence of α-oxidative processes. F-53B did not degrade to PFAAs and its constituents were mainly detected in the roots with minor uptake into the shoots. The results demonstrate the important role of precursors as an entry pathway for PFCAs into the food chain.

Investigating rate-limited sorption, sorption to air–water interfaces, and colloid-facilitated transport during PFAS leaching

“…Hence, it is highly plausible that the observed long-term leaching at t > 600 d in the lysimeter is attributable to the transformation of PFOA precursors, such as 8:2 diPAP. This is consistent with Guelfo et al ( 2020 ), who stated that precursor transformation may be more important than rate-limited leaching at field scale, and other studies (Röhler et al 2021 ; Schaefer et al 2022a ; Just et al 2022 ).…”

Evaluation of the Transformation and Leaching Behavior of Two Polyfluoroalkyl Phosphate Diesters in a Field Lysimeter Study

“…Hence, the high PFAS concentrations in the plant make up less than 0.1% of the overall detected PFAS mass and consequently only have a small influence on the total PFAS balance. A similar result was found by Just et al 30 for the uptake of 6:2 diPAP degradation products into maize plants with a recovery rate of 1.4% of the initially applied PFAS amount in the aboveground plant compartments.…”

“…Atmospheric deposition is assumed to be negligible, as no PFAS were detected in the system compartments (soil, leachate, and grass) of the control variant. Studies by Bizkarguenaga et al 33 and Just et al 30 demonstrated evidence of minimal diPAP uptake into plants. Mass Balance.…”

“…on diPAP degradation over time was not considered. In a study by Just et al, 30 a DT 50 of 33 days was calculated for the degradation of 6:2 diPAP in a soil-plant system. Here, maize plants were cultivated on 6:2 diPAP-applied soil in Mitscherlich pots under semi-outdoor conditions, clearly limiting the comparability of the different DT 50 values.…”

Phytoremediation of soil contaminated with per- and polyfluoroalkyl substances (PFAS)

“…Subsequently, instrumental analysis is performed most commonly using liquid chromatography (LC) coupled with tandem mass spectrometry (MS/MS) (Felizeter et al 2012; or high-resolution mass spectrometry (HRMS) (Just et al 2022). These techniques allow for identifying and quantifying specific PFAS in plant samples, providing insights into their presence and levels in different plant tissues.…”