Nanoglass toxicity in Eichhornia crassipes : uptake, photosystem II disruption, and redox imbalance

Anthropogenic pollutants increasingly threaten aquatic ecosystems, with emerging contaminants such as nanoglass (NG) particles raising concerns regarding their environmental persistence and potential ecological effects. This study provides experimental evidence of NG accumulation and associated phytotoxic responses in the aquatic macrophyte Eichhornia crassipes. FTIR, XRD, energy-dispersive X-ray spectroscopy (EDS), and field-emission scanning electron microscopy (FE-SEM) provided evidence of NG accumulation and distribution within leaf tissues. NG exposure altered leaf surface architecture, with increased surface irregularity and roughness, indicating structural perturbation. Exposure to NG (0–50 mg L−1) induced concentration-dependent morphological alterations, pigment loss, and oxidative stress. Chlorophyll fluorescence analysis revealed impairment of photosystem II (PSII), reflected by alterations in O–J–I–P transients and fluorescence parameters. Declines in F0, Fₘ, and Fᵥ/F0, together with increased F0/Fₘ, indicated impaired PSII photochemical performance. Energy flux parameters showed reductions in absorption (ABS/CSₘ), trapping (TR0/CSₘ), and electron transport (ET0/CSₘ), accompanied by altered energy dissipation (DI0/CSₘ), indicating disturbance of PSII energy utilization. Increased non-photochemical quenching (Kₙ) and decreased photochemical quenching (Kₚ) further suggested enhanced energy dissipation. Quantum yields and performance indices declined at higher NG concentrations, indicating progressive impairment of photosynthetic efficiency. SOD, CAT, and POD activities increased at moderate exposure but declined above 30 mg L−1, suggesting compromised antioxidant capacity under severe stress. Overall, NG exposure induced structural, photosynthetic, and redox disturbances in E. crassipes, highlighting its potential as an emerging stressor in aquatic plant systems.