Cyanide and metal pollution by urban snowmelt: impact of deicing compounds

Abstract

Highway and road deicing operations provide traffic safety during winter driving conditions in snowbelt areas. Using large quantities of deicing chemicals causes water quality problems that need to be addressed and remediated. Two specific problems are discussed, i.e., presence of cyanides in deicing salt and decreased partitioning of metals in snowmelt resulting from high salt concentrations. Complex ferrocyanide compounds are added to salt to prevent caking. By photodecomposition, these cyanides can be broken down to free toxic cyanide compounds. For toxic metals, salt decreases partitioning between adsorbed (precipitated) and dissolved metals, resulting in an increase in dissolved metals in salt laden snowmelt and consequently increasing toxicity.