RADIOECOLOGICAL STATE OF LAKES IN THE SOUTHERN URAL IMPACTED BY RADIOACTIVITY RELEASE OF THE 1957 RADIATION ACCIDENT

This paper is concerned with the distribution of Sr-90 and Cs-137 in l ake ecosystems in the southern Urals which were affected by the 1957 r adiation accident. In 1992, the levels of Sr-90 in the most highly con taminated lakes, which were removed from economic usages, were as foll ows: 17-120 Bq l(-1) in water, 70-110 kBq kg(-1) in fish and 2.9-5.2 k Bq kg(-1) in aquatic plants. In the lakes which are used in the fisher y, the levels of Sr-90 are 0.05-0.5 Bq l(-1) in water and 4-550 Bq kg( -1) in fish. The levels of Cs-137 in these lakes are 0.03-0.6 Bq l(-1) in water and 2-33 Bq kg(-1) in fish. In the first few years following the accident, a dose rate level of 10(-2) Gy day(-1) to molluscs, bot tom-dwelling fish and aquatic plants could be exceeded in the most hig hly contaminated lakes of Uruskul' and Berdyanish. In 1992, the backgr ound exposure level for fish from these lakes was still exceeded by a factor of 1000. In the other lakes, the doses to aquatic organisms wer e considerably lower. Doses to the population from lake fish consumpti on do not exceed 10(-3) Sv year(-1). Copyright (C) 1996 Elsevier Scien ce Limited.