Lead phytoremediation and selective biogas production from Typha latifolia L.: physiological and biochemical responses

Background: Lead (Pb) contamination in aquatic environments is increasing worldwide, yet studies integrating metal uptake, plant tolerance mechanisms, and post-remediation biomass valorization remain limited. Bridging phytoremediation efficiency with sustainable biomass management is essential to advance nature-based solutions. Objectives: This study evaluated the phytoremediation potential of the emergent macrophyte Typha latifolia, integrating Pb uptake and removal efficiency, physiological stress responses, and biogas production from Pb-exposed biomass. Methods: Plants were exposed under controlled hydroponic conditions to Pb concentrations of 50, 100, 1000, and 10,000 µg L⁻¹ for 48 and 168 h. Pb accumulation and translocation were quantified in roots and leaves, along with changes in aqueous Pb concentrations. Morphological traits and oxidative stress biomarkers were assessed in roots and leaves, while photosynthetic pigments were measured in leaves. Multivariate analyses, including the integrated biomarker response (IBR) index and principal component analysis (PCA), were applied. Biogas production assays were conducted using biomass from control plants and selected Pb treatments (1000 and 10,000 µg L⁻¹). Results: Lead accumulated mainly in roots, with limited translocation to leaves. Aqueous Pb concentrations decreased by >60% at the highest exposure after 168 h. Despite substantial Pb accumulation, plants showed minimal morphological changes, indicating high short-term tolerance. Biochemical responses suggested activation of antioxidant defenses, together with a moderate increase in chlorophyll content in leaves at higher Pb concentrations, indicative of a physiological stress response supported by IBR and PCA analyses. Notably, shoots exposed to 1000 µg L⁻¹ Pb produced the highest biogas yield. Conclusions: T. latifolia exhibits strong Pb tolerance, effective phytostabilization capacity, and maintains biomass suitability for energy recovery after exposure. These findings highlight its dual role in Pb-contaminated systems, combining remediation potential with sustainable biomass valorization within a circular bioeconomy framework.