title: Competing mechanisms for perfluoroalkyl acid accumulation in plants revealed using an Arabidopsis model system.
abstract: Perfluoroalkyl acids (PFAAs) bioaccumulate in plants, presenting a human exposure route if present in irrigation water. Curiously, accumulation of PFAAs in plant tissues is greatest for both the short-chain and long-chain PFAAs, generating a U-shaped relationship with chain length. In the present study, the authors decouple competing mechanisms of PFAA accumulation using a hydroponic model plant system (Arabidopsis thaliana) exposed to a suite of 10 PFAAs to determine uptake, depuration, and translocation kinetics. Rapid saturation of root concentrations occurred for all PFAAs except perfluorobutanoate, the least-sorptive (shortest-chain) PFAA. Shoot concentrations increased continuously, indicating that PFAAs are efficiently transported and accumulate in shoots. Tissue concentrations of PFAAs during depuration rapidly declined in roots but remained constant in shoots, demonstrating irreversibility of the translocation process. Root and shoot concentration factors followed the U-shaped trend with perfluoroalkyl chain length; however, when normalized to dead-tissue sorption, this relationship linearized. The authors therefore introduce a novel term, the "sorption normalized concentration factor," to describe PFAA accumulation in plants; because of their hydrophobicity, sorption is the determining factor for long-chain PFAAs, whereas the shortest-chain PFAAs are most effectively transported in the plant. The present study provides a mechanistic explanation for previously unexplained PFAA accumulation trends in plants and suggests that shorter-chained PFAAs may bioaccumulate more readily in edible portions.
authors.affiliation: Re-Inventing the Nation's Urban Water Infrastructure Engineering Research Center (ReNUWIt), Stanford University, Stanford, California, USA.|Department of Civil & Environmental Engineering, Stanford University, Stanford, California, USA.
authors.forename: Claudia E
authors.initials: CE
authors.lastname: Müller
authors.affiliation: Re-Inventing the Nation's Urban Water Infrastructure Engineering Research Center (ReNUWIt), Stanford University, Stanford, California, USA.|Department of Civil & Environmental Engineering, Stanford University, Stanford, California, USA.
authors.forename: Gregory H
authors.initials: GH
authors.lastname: LeFevre
authors.affiliation: Institute of Environmental Engineering, Swiss Federal Institute of Technology, Zürich, Switzerland.
authors.forename: Anca E
authors.initials: AE
authors.lastname: Timofte
authors.affiliation: Re-Inventing the Nation's Urban Water Infrastructure Engineering Research Center (ReNUWIt), Stanford University, Stanford, California, USA.|Department of Civil & Environmental Engineering, Stanford University, Stanford, California, USA.
authors.forename: Fatima A
authors.initials: FA
authors.lastname: Hussain
authors.affiliation: Re-Inventing the Nation's Urban Water Infrastructure Engineering Research Center (ReNUWIt), Stanford University, Stanford, California, USA.|Department of Chemical Engineering, Stanford University, Stanford, California, USA.
authors.forename: Elizabeth S
authors.initials: ES
authors.lastname: Sattely
authors.affiliation: Re-Inventing the Nation's Urban Water Infrastructure Engineering Research Center (ReNUWIt), Stanford University, Stanford, California, USA.|Department of Civil & Environmental Engineering, Stanford University, Stanford, California, USA.
authors.forename: Richard G
authors.initials: RG
authors.lastname: Luthy
mesh_terms: D017360:Arabidopsis / Q000737:chemistry* / Q000378:metabolism; D005466:Fluorocarbons / Q000032:analysis* / Q000378:metabolism; D018527:Hydroponics; D018517:Plant Roots / Q000737:chemistry / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000378:metabolism
chemical_list: D005466:Fluorocarbons; D014874:Water Pollutants, Chemical
keywords: Bioaccumulation; Environmental fate; Perfluoroalkyl substance; Plant