Thallium accumulation and ecological restoration mechanisms in brake ferns (Pteris vittata L.) from wastewater

This study systematically investigated the accumulation and detoxification mechanisms of brake ferns ( Pteris vittata L. ) in thallium (Tl) contaminated wastewater. Under Tl concentrations of 1–20 μg·L⁻¹ , the brake fern exhibited good Tl tolerance‌, achieving bioconcentration factors of 64–202 with over 89 % removal efficiency. Kinetic experiments demonstrated that under prolonged exposure conditions, the Tl uptake rate in brake fern was 0.043 μg·g⁻¹ ·d⁻¹ . Competitive absorption between Tl and potassium (K) was observed in brake fern. The dominant form of Tl in the plant tissues was monovalent. Subcellular analysis revealed tissue-specific transport pathways. In the roots, Tl transport was dominated by the apoplastic pathway, with Tl largely retained in the cell walls. In contrast, translocation to the shoots relied on the transmembrane transport pathway, ultimately resulting in Tl storage in the organelles (such as chloroplasts), cytoplasm and vacuoles. The fern employed coordinated detoxification through nutrient regulation, transport pathway switching, and intracellular complexation. These findings demonstrate brake fern's potential for phytoremediation of Tl-contaminated water, providing insights into its metal accumulation mechanisms and tolerance strategies. • Brake ferns had a good remediation effect on Tl-contaminated wastewater. • The highest absorption and removal rate of brake ferns was 92.76 %. • Under 1–20 μg·L −1 of Tl, the BCF was in the range of 64.35–202.04. • Tl was primarily transported via the apoplastic pathway in root cells. • Tl was primarily transported via the transmembrane pathway in shoot cells.