Effect of road salt on soil and water properties in Halifax, Nova Scotia

Abstract

Road salt is a crucial public safety tool to protect people on winter roads, but it disperses from roads and impacts the environment. Increased salinity affects both soil and water systems with adverse effects observed on vegetation, nutrient cycling, and aquatic organisms. Nova Scotia applies the most road salt of all the Canadian provinces per unit area with a total of 230,182 tonnes. I compiled and analyzed water conductivity data for the Halifax Regional Municipality (HRM) from datasets provided by the Department of Fisheries and Oceans and Halifax Water to determine the spatial and temporal trends in conductivity. Conductivity has been increasing in most HRM lakes since at least 1980, but seasonal trends were inconsistent. To better understand salinity of soil and lakes, fieldwork was conducted at five lakes in Dartmouth, Nova Scotia that represented sites exposed to or protected from road salt. At each lake, we sampled water and soil on a side that was closer to roads/road salt application, and on another side further away. Statistical analysis showed no significant effect of proximity to road salt application on water conductivity (P = 0.834). There was a significant difference between protected and exposed sites (P = 0.0187). Soil electrical conductivity was also measured on both sides of the lakes at distances of 0, 10, and 20 m from the lake before (fall) and after (winter) road salt application. Soil conductivity was significantly higher at 0 m (compared to 10 m, P = 0.020, and compared to 20 m, P < 0.001) and before road salt application (P = 0.014). There was no significant effect of protection (P = 0.079) or proximity to road salt application (P = 0.184) on soil conductivity. Based on these results, I concluded that road salt is negatively impacting many lakes in the HRM.