Traffic-derived contaminant loading in snow storage facilities during spring melt

Area of Science:

• Environmental Science
• Water Quality Management
• Urban Hydrology

Background:

• Stormwater runoff from urban areas, including snowmelt (SM), often enters water bodies untreated.
• Limited data on snowmelt quality and loading hinders effective management and treatment strategies.
• Urban snow storage facilities accumulate pollutants from roads and mixed land use catchments.

Purpose of the Study:

• To assess the quality and toxicity of snowmelt runoff from urban snow storage facilities in a cold climate, semi-arid Canadian city.
• To identify key pollutants and their concentrations during spring snowmelt events.
• To evaluate the ecotoxicity of snowmelt on aquatic organisms.

Main Methods:

• Sampling of snow piles and snowmelt runoff from four urban snow storage facilities in Saskatoon, Saskatchewan, over two years (2019-2020).
• Analysis of water samples for parameters including pH, EC, TDS, TSS, COD, DOC, metals, chloride, and PAHs.
• Assessment of ecotoxicity using Raphidocelis subcapitata and Vibrio fischeri.

Main Results:

• Significant spikes in TSS, TDS, chloride, and manganese were observed during specific snowmelt events.
• Elevated concentrations of aluminum and PAHs (e.g., pyrene, phenanthrene, anthracene) were detected.
• Pollutant concentrations in snow piles and snowmelt runoff frequently exceeded national aquatic toxicity guidelines.

Conclusions:

• Urban snowmelt is a significant source of various pollutants, including heavy metals and PAHs.
• Snowmelt runoff poses a considerable risk to aquatic ecosystems due to exceeding toxicity thresholds.
• Improved management and treatment strategies for urban snowmelt are necessary to protect water quality.