An investigation into the long-term binding and uptake of PFOS, PFOA and PFHxS in soil - plant systems

This study investigated the potential aging and plant bioaccumulation of three perfluoroalkyl acids (PFAAs), perfluorosulphonic acid (PFOS), perfluorooctanoic acid (PFOA) and perfluorohexanesulphonic acid (PFHxS) in 20 soils over a six-month period. Sorption coefficients (Log K-d) ranged from 0.13-1.28 for PFHxS, 0.17-1.06 for PFOA and 0.98-2.03 for PFOS, respectively, and bioaccumulation factors (Log BAFs) ranged from 0.29-1.24, 0.22-1.46 and 0.05-0.65 for PFHxS, PFOA and PFOS, respectively. Over the six-month period, K-d values significantly increased for PFHxS and PFOA but the magnitude of the increase was very small and did not translate into differences in plant PFAA-concentrations between aged and freshly spiked treatments. The K-d and BAF values were modelled by multiple linear regression (MLR) to soil physico-chemical properties and by partial least squares regression to soil spectra acquired by mid-infrared spectroscopy (DRIFT PLSR). Modelling of each PFAA was influenced by different soil properties, including organic carbon, pH, CEC, exchangeable cations (Ca2+, Mg2+, Na+ and K+) and oxalate extractable Al. BAF values were not strongly correlated to any soil property but were inversely correlated to K-d values. Our results indicate that limited aging occurred in these soils over the six-month period.

Automated summary

This study investigated the aging and bioaccumulation of three perfluoroalkyl acids in 20 soils over a six-month period. Results showed limited aging in the soils during the study period, with small changes in PFAA concentrations in plants. The models developed for each PFAA were influenced by different soil properties, highlighting the complex interactions between PFAAs and soil characteristics.