All urban water discharges are potentially hazardous to the environment; however, discharges in cold-climate regions seem particularly severe. This severity arises from the long winter period where an accumulation of pollutants occurs. Common features of both snow and meltwater is that they are complex mixtures of different types of substances, such as heavy metals, hydrocarbons, nutrients, bacteria, oxygen depleting substances, suspended solids and salts. The most common heavy metals in highway runoff are lead, zinc, iron, copper, cadmium, chromium and nickel. Pollutant sources that dominate during the cold period include high emissions from cold car engines, exhaust fumes, heating, tire wear, and abrasion of asphalt due to the use of studded tires. Winter road maintenance, which involves spreading salt and sand, also contributes to pollution by increasing suspended solids in runoff, release of chloride, corrosion of metal surfaces and structures, and higher mobility of metals. During the snowmelt period, urban snow may have a detrimental effect on water, soil, vegetation, wildlife and micro-organisms. The impact depends both on the properties of the melt water, such as concentrations of pollutants, volume, flow and temperature, and on the properties of the receiving water bodies.
The objective of the project is to characterize and study the behaviour and transport of pollutants, i.e., suspended solids, particles and heavy metals, in road runoff from a small urban catchment during snowmelt and rainfall. The result will constitute a basis for essential considerations concerning the selection and design of environmental management practices and techniques in a cold climate. As well, the result will be used for improvements of existing model concepts included in commonly used softwares for the dynamics of total suspended solids (TSS) and heavy metal transport during snowmelt induced runoff.
The project is running from 2005-2007 and is supported by The Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning, FORMAS which is gratefully acknowledged.