Uptake, Acropetal Translocation, and Enantioselectivity of Perfluorooctane Sulfonate in Maize Coexisting with Copper

Plant uptake and translocation of perfluorooctane sulfonate (PFOS) are critical for food safety and raise major concerns. However, those processes are associated with many undisclosed mechanisms, especially when PFOS coexist with heavy metals. In this study, we investigated the effect of copper (Cu) on PFOS distribution in maize tissues by assessing the PFOS concentration and enantioselectivity. The presence of <100 mu mol/L Cu exerted a limited effect on PFOS bioaccumulation, while >100 mu mol/L Cu damaged the root cell membrane and increased root permeability, resulting in a higher PFOS concentration in roots. The suppression of acropetal translocation might be attributed to Cu inhibition of carrier proteins. The enantiomer fraction (EF) of lm-PFOS at <100 mu mol/L Cu was higher than that in a commercial product (0.5). Racemic PFOS was detected at >100 mu mol/L Cu in roots and the EF variation changed from positive to negative in shoots. These EF results evidenced the existence of a protein-mediated uptake pathway. Besides, this study indicated the challenge of chiral signature application in PFOS source identification, given the effects of heavy metals and plants on PFOS enantioselectivity. The findings provide insight into PFOS bioaccumulation in plants cocontaminated with Cu and will facilitate environmental risk assessment.

Automated summary

The study found that the presence of different concentrations of copper (Cu) had varying effects on PFOS, with low concentrations causing an increase in PFOS concentration in roots and high concentrations damaging root cell membranes and increasing root permeability. It was also observed that Cu inhibition of carrier proteins could lead to the suppression of acropetal translocation of PFOS, and the presence of a protein-mediated uptake pathway was evidenced by enantiomer fraction (EF) results.