Phytoremediation of nanoparticle contaminated soil using the fast growing herbaceous plant Solidago altissima

This study investigated the potential of the fast-growing invasive plant Solidago altissima for phytoremediation of nanoparticle-contaminated soils. Plants were grown in soils treated with titanium dioxide (TiO₂) and silver (Ag) nanoparticles at concentrations of 0, 10, 100, 1000, and 5000 mg/kg to evaluate growth performance and nanoparticle accumulation. TiO₂ and Ag nanoparticles were selected due to their widespread industrial use and increasing environmental occurrence, raising concerns about their persistence in terrestrial ecosystems. S. altissima exhibited stable eco-physiological performance, including chlorophyll content, height growth, and biomass production across treatment levels. The plant tolerated TiO₂ nanoparticles up to 5000 mg/kg without significant growth inhibition. In Ag nanoparticle-treated soils, biomass showed a concentration-dependent response: compared with the control (9.70 g), total dry biomass increased at 10 mg/kg (11.74 g) but decreased at higher concentrations (6.72-6.43 g at 1000-5000 mg/kg). Nanoparticle accumulation was predominantly observed in roots, and root concentrations increased with increasing soil nanoparticle levels, indicating strong belowground retention of Ti and Ag. The extensive rhizome system and high biomass production of S. altissima suggest its potential for soil-targeted phytoremediation. Overall, the results indicate that the remediation role of S. altissima is more consistent with root-based phytostabilization than with shoot-based phytoextraction. These findings suggest that utilizing this species in disturbed environments, such as roadside soils where it is already widely established, may provide dual benefits by contributing to nanoparticle stabilization in soils while supporting invasive plant biomass management. Further studies are needed to evaluate long-term ecological impacts and field-scale applicability.