Impact of airborne pollution on the drainage area of subarctic lakes and fish.

Within the period from 1989 to 1993, the impact of heavy metals and acid oxides on lakes, more than 100 km distant from the nearest source of pollution (enterprises of the copper-nickel industry), has been investigated. On the basis of complex investigations (chemical composition of snowpack and lake sediments, state of fish organisms and populations), it was discovered that there is intensive precipitation of heavy metals and acid oxides within the catchment of the lake Kochejavr. The catchment is characterized by a natural buffer capacity to neutralize acid precipitation. Active accumulation of heavy metals is observed in lake sediments. Metal accumulation causes subtoxic effects on the lake fish. The levels of precipitation of nickel and copper of 0.9 mg/m2 per year over long periods was found to be dangerous for biological systems of freshwater catchments.