Fate of 6:2 fluorotelomer sulfonic acid in pumpkin (Cucurbita maxima L.) based on hydroponic culture: Uptake, translocation and biotransformation
By Shuyan Zhaoa. Tiankun Lianga, Lingyan Zhub, Liping Yangb, Tianqi Liua, Jia Fua, Bohui Wanga, Jingjing Zhana, and Lifen Liua
July 22, 2019
6:2 fluorotelomer sulfonic acid (6:2 FTSA) is currently used as an alternative to perfluorooctanesulfonate (PFOS) and is widely detected in the environment. The uptake, translocation and biotransformation of 6:2 FTSA in pumpkin (Cucurbita maxima L.) were investigated by hydroponic exposure for the first time. The root concentration factor (RCF) of 6:2 FTSA was 2.6–24.2 times as high as those of perfluoroalkyl acids (PFAAs) of the same or much shorter carbon chain length, demonstrating much higher bioaccumulative ability of 6:2 FTSA in pumpkin roots. The translocation capability of 6:2 FTSA from root to shoot depended on its hydrophobicity. Six terminal perfluorocarboxylic acid (PFCA) metabolites, including perfluoroheptanoic acid (PFHpA), perfluorohexanoic acid (PFHxA), perfluoropentanoic acid (PFPeA), perfluorobutanoic acid (PFBA), perfluoropropionic acid (PFPrA) and trifluoroacetic acid (TFA) were found in pumpkin roots and shoots. PFHpA was the primary metabolite in roots, while PFBA was the major product in shoots. 1-aminobenzotriazole (ABT), a cytochromes P450 (CYPs) suicide inhibitor, could decrease the concentrations of PFCA products with dose-dependent relationships in pumpkin tissues, implying the role of CYP enzymes involved in plant biotransformation of 6:2 FTSA. This study indicated that the application of 6:2 FTSA can lead to the occurrence of PFCAs (C2–C7) in plants.
• Pumpkin root accumulated 6:2 FTSA efficiently and prone to acropetal translocation.
• The translocation capability of 6:2 FTSA was dependent on its hydrophobicity.
• 6:2 FTSA could be transformed to PFHpA, PFHxA, PFPeA, PFBA, PFPrA and TFA in plant.
• PFHpA was the main metabolite in root, while PFBA was the major product in shoot.
• ABT inhibited the formation of PFCAs in pumpkin via the inhibition of CYP enzymes.