Comprehensive evaluation of enrofloxacin removal and toxicokinetic dynamics in Typha latifolia L.: Uptake, bioaccumulation, elimination, biotransformation, and plant responses

Animal feeding operation effluents are major sources of veterinary antibiotics in freshwaters. Enrofloxacin (ENRO) is an emerging contaminant of increasing environmental concern. Phytoremediation using wetland macrophytes represents a sustainable and cost-effective mitigation strategy. In this study, a biotransformation kinetic model for ENRO conversion into ciprofloxacin (CIPRO) was systematically established for the first time in Typha latifolia , and the influence of its zwitterionic speciation on uptake, bioaccumulation and translocation was elucidated. Plants were hydroponically exposed to environmentally relevant concentrations (0, 10, and 100 μg/L) for 35 days, including exposure and depuration phases, to evaluate phytotoxicity, removal efficiency, toxicokinetic, and biotransformation. ENRO induced a transient hormetic stimulation of root elongation and increased photosynthetic pigment contents, without detectable morpho-physiological or biochemical toxicity effects. Removal efficiency reached ∼90%, following first-order kinetics ( k r = 0.32 d −1 and 0.44 d ‐1 at 10 and 100 μg/L, respectively). Uptake and elimination kinetics were significant in both roots and leaves, with roots as the dominant accumulation compartment with steady-state bioaccumulation factors BAF ss = 238.88 ± 25.83 L/kg and 13,082.97 ± 1541.29 L/kg, whereas leaf accumulation was markedly lower ( BAF ss = 2.01 ± 0.69 to 168.51 ± 27.11 L/kg). At the experimental pH (5.5), ENRO occurred mainly as zwitterionic and cationic species. Electrostatic attraction to negatively charged functional groups at the root surface likely enhanced outer-layer retention, restricted symplastic diffusion, and limited shoot translocation, mechanistically explaining the preferential root accumulation and slow upward mobility observed. Biotransformation to CIPRO occurred primarily in roots, and kinetic modeling confirmed significant transformation dynamics in leaves, supporting both in situ formation and translocation processes. Overall, T. latifolia exhibited high tolerance and strong phytoremediation capacity for ENRO. This study provides a quantitative and mechanistic framework for the toxicokinetics of ENRO, including uptake, accumulation, elimination, and biotransformation, in T. latifolia , supporting its application in mitigating veterinary antibiotic contamination.