Lake Padderudvann, in Asker, Norway, is exposed to pollution from traffic and from road salting. The lake was studied by the University of Oslo and by the Norwegian Institute of Water Research between 1947 and 2003. The investigations involved studying the types of pollution from the road, the effects on plant and animal life and the possible long-term effects. The studies showed that salting of the E18 highway increased salt concentrations in the lake. Specific conductivity increased, particularly in the deeper water, and the circulation depth decreased due to the accumulation of salts. Chemical analysis of water and sediments showed a recent decrease in lead and increases in nickel and copper levels. Levels of total polycyclic aromatic hydrocarbons were lower in 2001 than 1991. Hexachlorobenzene and octachlorostyrene were found in high concentrations. The problems associated with the accumulation of road salt in the deep water are discussed.
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