Changes in Salinity and Toxicity of Soil Contaminated with De-icing Agents during Growing Season

Abstract

De-icing agents (ice and snow control materials) are applied to prevent ice and snow deposits on the roads in winter period. The extensive use of de-icing agents in countries with cold climate creates problems for the environment. In this study, the dynamics of de-icing salt concentrations in sod-podzolic soil was revealed in laboratory and field experiments. Twelve de-icing agents of different chemical groups (chlorides, acetates and formates) were studied. Under laboratory conditions, application of high doses of chloride reagents led to an increase of salt concentration in soil up to a level of slightly saline soils. Contaminated soils had salt levels high enough to be toxic to plants and soil microorganisms. However, under field conditions, soil salinity eventually decreased due to salt washout by atmospheric precipitation. By the end of the growing season, salt concentration corresponded to a background level. The decrease in salt concentration was accompanied by a decrease in soil toxicity. Acetate and formate de-icing agents demonstrated the least environmental effect. Our results suggest that magnesium chloride was the least harmful among the de-icers of chloride group while the most commonly used road de-icing salt sodium chloride was the most persistent and toxic to terrestrial plants and soil microbiota.