Phytoremediation of road salt affected soils in the Toronto region using native halophytes

Freshwater salinization is a growing concern in areas of the world experiencing freezing winter temperatures. Winter salt applied to roads can flow directly to surface water and groundwater, but can also be stored in roadside soil for months or years after application. Halophytes (i.e. salt-tolerant plants) remove excess salt from soil and can assist with remediation of saline soils. This study aimed to determine the ability of native halophytes to remediate road salt contaminated sites over two growing seasons.

Four halophytes native to the Toronto, Canada region were planted in experimental plots next to a road that receives salt in the winter months. Two accumulator halophytes (Panicum virgatum and Sporobolus cryptandrus) and two recretohalophytes (Sporobolus michauxianus and Bouteloua curtipendula) were selected. Each species was planted in its own 2 × 6 m plot according to literature recommended planting densities. Plant and soil samples were collected at the end of each growing season to evaluate the amount of salt removed from soil and the amount of salt taken up by the plants.

The accumulator, P. virgatum, and the recretohalophyte, S. michauxianus demonstrated the greatest potential for short remediation timelines (< 2 years after their second growing season). S. michauxianus and P. virgatum extracted approximately 22,000 mg/m² and 17,000 mg/m² of chloride over a single growing season, respectively.

This is the first multi-year in situ study to examine the potential for halophytes to remediate road salt contamination. Halophytes provide a unique nature-based solution for the remediation and mitigation of road salt contamination.

The online version contains supplementary material available at 10.1007/s11104-025-07873-x.