LONG-TERM EFFECTS OF THE USE OF DE-ICING SALT ON THE ROADSIDE ENVIRONMENT. PART II: GROUNDWATER AND SURFACE WATER

A road in operation with its traffic can pose a serious pollutant threat to groundwater and surface water in the vicinity of major roads. Examples of pollutants are salt for deicing and dustbinding; metals from corrosion of vehicles and wear of road surface and tires; and hydrocarbons from the wear of road surface, tires, exhaust, oils, and hazardous goods discharged in the case of an accident. In Sweden about 300,000 tonnes of sodium chloride are used annually by the Swedish National Road Administration for deicing purposes. In addition, the local municipalities also use salt for deicing purposes. The annual amount of road wear was estimated to 300,000 tonnes for the season 1993/94. The use of studs improve the friction but increase the wear and grinding effect on winter roads. The wear of a wet surface is reported to be two to seven times the wear of a dry surface, and hence, the grinding effect may be further increased by the use of deicing salt. The movement of pollutants from the road to the surrounding environment will involve runoff from roads, airborne spreading, and infiltration from road construction and road area. Eventually, all pollutants from roads, which are not subjected to degradation, will be transported either to surface water or groundwater. In Sweden, the major roads are deiced with 10-20 tonnes of sodium chloride per km annually. On the road the effects of the salt are desired and in the sea a high salt concentration is natural, but on its way the salt ions will pass through an environment where the natural concentration of sodium chloride is low, involving an impact. The chloride ion is a good tracer. It is conservative and highly soluble and not subjected to retardation or degradation. A small part of the sodium may be retained in soil but almost all of the deicing salt will be either infiltrated and found in groundwater, or form runoff and be found in surface water. Furthermore several investigations show that heavy deicing salt application increases metal mobilization. The aim of this paper is to discuss the impacts on groundwater and surface waters of deicing salt application and to relate the increased chloride concentrations to natural concentrations.

Language

  • English

Media Info

  • Features: Figures; References; Tables;
  • Pagination: 12p

Subject/Index Terms

Filing Info

  • Accession Number: 00795329
  • Record Type: Publication
  • Report/Paper Numbers: Session F
  • Files: TRIS, TRB
  • Created Date: Jul 19 2000 12:00AM