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- and long-chain PFAAs, generating a "U-shaped" relationship with chain-length. In the present study we 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. We therefore introduce a novel term, the Sorption Normalized Concentration Factor (SNCF), to describe PFAA accumulation in plants: due to their hydrophobicity, sorption is the determining factor for long-chain PFAAs, while 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. This article is protected by copyright. All rights reserved.