The Solid Speciation of 90Sr, 137Cs, 226Ra, 238U and 239,240Pu in Surface Soils from Sites of Special Radiological Interest in Kazakhstan

The solid speciation of some radiologically important radioelements has been examined in soils sampled at the former Semipalatinsk (Nuclear) Test Site (STS) and at Kurdai, the site of a former major uranium mining operation − both situated in Kazakhstan. Specifically, the partitioning of radiostrontium, radiocaesium and plutonium has been examined using sequential extraction on selected soils from the test site, while the partitioning of radium and uranium has been evaluated in soils at Kurdai. The data show that at the STS, in general, little (if any) of the radiostrontium, radiocaesium and plutonium is in an exchangeable form, with the great bulk of the radiostrontium and radiocaesium in a strongly bound or refractory form. In the case of plutonium, the proportion in a strongly bound or refractory form varies from 40% to 95% depending on site and appears to be a function of the explosive yield involved. At the Kurdai ore deposit, less than 5% of the uranium and radium is in an exchangeable form, with some 35-60% of the uranium and the bulk of the radium in a strongly bound or residual form.