LARGE areas of western Siberia and the Arctic Ocean are facing threat of conta-mination by deposits of radioactive salts in a Ural Mountains lake, says Yuri Vishnevsky, head of the Russia's Nuclear Supervision Service. The Mayak nuclear power plant has dumped nuclear waste in the ponds in the region. Consequently, a radioactive deposit has been formed in Karachai lake.

Since its inception in the late 1940s, the plant had been processing plutonium for atomic bombs. In this period, it dumped tonnes of raw radioactive waste into local rivers. Though Mayak stopped the production of plutonium in 1992, it continues to reprocess spent fuel and is engaged in the dismantling of nuclear weapons.

The radioactive waste in local water bodies has resulted in the formation of a "lens of radioactive salts" in the lake. The formation is moving towards four Siberian rivers at a speed of 80 metres a year, says Vishnevsky. If this deposit is sucked into the water supply of the Riber Techa, Tobol and Irtysh, all of the western Siberia and the Arctic Ocean could become polluted within a decade.