Phytoremediation of Road Salt-Impacted Soils by Local Roadside Plant Species: Comparative Study and Field Evaluation

In snowy regions across North America, road salt (sodium chloride, NaCl) is widely applied as a deicing agent but can infiltrate adjacent soils and water systems, leading to salinization and ecological degradation. The phytoremediation potential of roadside plant species commonly exposed to deicing salts remains insufficiently characterized. This study assessed the NaCl phytoremediation potential of five roadside plant species, creeping red fescue, tall fescue turfgrass, big bluestem, western wheatgrass, and common sunflower (Helianthus annuus L.), by analyzing Na and Cl accumulation across different growth stages. Plants cultivated in the greenhouse were harvested at different days after NaCl spiking, with soil, root, and shoot samples collected for Na and Cl concentration analysis. H. annuus exhibited the highest salt accumulation capacity. At 90 days, H. annuus accumulated 13.4 ± 3.5 mg Na and 16.4 ± 2.6 mg Cl in roots, and 209.2 ± 43.3 mg Na and 411.5 ± 70.8 mg Cl in shoots, corresponding to approximately 42% and 52% of the estimated reference Na and Cl inventories, respectively. More than 90% of the absorbed salts were stored in shoot tissues, indicating effective translocation and storage in harvestable biomass. A highway-roadside field evaluation with controlled NaCl addition supported the potential of H. annuus for roadside salt phytoaccumulation, with area-normalized biomass accumulation of 0.35–0.42 g/m2 for Na and 9.9–10.1 g/m2 for Cl. These findings suggest that incorporating H. annuus into roadside vegetation systems could potentially simultaneously reduce soil salinity and generate harvestable biomass with potential for secondary utilization, supporting sustainable management of salt-impacted environments.