Bioaccumulation and physiological responses of common duckweed (Lemna minor L.) treated with legacy and emerging per- and polyfluoroalkyl substances (PFAS) under acute and chronic exposure conditions.

Per- and polyfluoroalkyl substances (PFAS) are persistent and bioaccumulative contaminants of emerging concern in aquatic ecosystems, yet their uptake dynamics and physiological effects on macrophytes remain poorly understood. This study investigated PFAS bioaccumulation and physiological responses of Lemna minor exposed to seven PFAS compounds under both acute and chronic conditions. Longer exposure durations resulted in detectable accumulation of a greater number of PFAS, particularly at lower exposure concentrations. Concentration-dependent accumulation was observed, although the direction and magnitude of these relationships varied among PFAS types. PFBS showed the highest accumulation, with concentrations up to 8736 ± 5715 ng/g dw detected after 10 days of exposure to 100,000 ng/L. When expressed as bioconcentration factors (BCFs), an inverse relationship with exposure concentration indicated higher uptake efficiency at environmentally relevant concentrations. The highest BCF (6076 ± 898 L/g) was observed for PFBS after 20 days of exposure to 1 ng/L. Differences in accumulation and BCF values were attributed to functional group and chain length, which affect solubility and hydrophobicity. Despite measurable bioaccumulation, physiological responses were generally minor, as neither growth nor photosynthetic efficiency (Fv/Fm and Y(II)) showed consistent impairment. Growth stimulation was observed in a limited number of treatments, suggesting potential hormetic effects. Overall, these findings highlight that both exposure duration and concentration range should be considered when assessing PFAS bioaccumulation in macrophytes, and that integrating time-dependent accumulation into risk assessments is essential for accurately evaluating PFAS behaviour and ecological risks.