The rate of recent sedimentation in Lake Teletskoe according to gamma-spectroscopy (Cs-137) data

A gamma-spectroscopic analysis of the upper (to 20 cm) layer of the Teletsk oe bottom sediments was carried out immediately at the sites of investigati ons. A total of 30 sites were studied for Cs-137 distribution throughout th e bottom section. The content of Cs-137 varies from 1-5 to 130-140 Bq/kg. M aximum 137Cs concentrations are observed at depths of 2-10 cm. The horizon of the maximum 137Cs contamination is dated to 1963. The horizon dated to 1 948 is taken as the upper boundary of the "preatomic" sedimentation period. The known depth and time of formation of these bench marks permitted estim ation of the rate of recent (the last 50 years) sedimentation in the Telets koe basins. On the most part of the lakescape the rate changes by 1-2 mm/ye ar, averaging 1.33 mm/year. The spatial variations in sedimentation rate ar e governed mainly by the dynamics of the lake waters. The modern resources of buried Cs-137 are estimated at 0.2-0.5 Bq/cm(2) and correlate with the s edimentation rate.