Seasonal performance of field bioretention systems in retaining phosphorus in a cold climate: Influence of prolonged road salt application

Jaeleah Goor; Julia Cantelon; Charles Christopher Smart; Clare E Robinson

doi:10.1016/j.scitotenv.2021.146069

Seasonal performance of field bioretention systems in retaining phosphorus in a cold climate: Influence of prolonged road salt application

Sci Total Environ. 2021 Jul 15:778:146069. doi: 10.1016/j.scitotenv.2021.146069. Epub 2021 Feb 26.

Authors

Jaeleah Goor¹, Julia Cantelon², Charles Christopher Smart³, Clare E Robinson⁴

Affiliations

¹ Department of Civil and Environmental Engineering, Western University, London, ON N6A 5B9, Canada.
² Department of Civil and Environmental Engineering, Western University, London, ON N6A 5B9, Canada; Department of Geography and Environment, Western University, London, ON N6A 5B9, Canada.
³ Department of Geography and Environment, Western University, London, ON N6A 5B9, Canada.
⁴ Department of Civil and Environmental Engineering, Western University, London, ON N6A 5B9, Canada. Electronic address: crobinson@eng.uwo.ca.

PMID: 33714832
DOI: 10.1016/j.scitotenv.2021.146069

Abstract

Bioretention systems are popular low impact development stormwater management features designed to remove pollutants, including phosphorus (P), from urban stormwater runoff. While the performance of bioretention systems in retaining P has been well studied, seasonal variability of P retention in field-scale systems installed in cold climates, including the influence of high road de-icing salt (sodium chloride) inputs, remains unclear. Two large field-scale bioretention systems installed in London, Ontario, Canada were monitored over their initial operational period to evaluate the seasonal trends in the retention of different forms of P in bioretention systems and the impact of high salt loading. Over the 12-month monitoring period, a net retention of total P and dissolved organic P, and a net release of soluble reactive P and total dissolved P mass were observed. Reduced hydrological performance and increased effluent P concentrations resulted in high P release from the bioretention systems in early to mid-spring (March and April), with most release occurring during a few individual large precipitation events. Laboratory-scale column experiments were performed using the engineered soil media installed in the field-scale bioretention systems to isolate the effect of high salt loading on P release. Column experiments combined with field data indicate that prolonged high salt loads through winter and spring may have contributed to elevated spring P release, mostly in the form of soluble reactive P, from the field-scale bioretention systems. Findings from this study are needed to better understand the performance of bioretention systems with respect to P retention as required to improve urban stormwater management in cold climates. Results have implications for further investigations of the impact of road salt on P mobility in bioretention systems and more broadly in roadside soils and groundwater systems.

Keywords: Cold climate; De-icing salt; Low impact development; Nutrients; Stormwater management systems.

MeSH terms

Cold Climate
London
Ontario
Phosphorus* / analysis
Rain*
Seasons
Sodium Chloride
Soil

Substances

Soil
Phosphorus
Sodium Chloride