Radionuclide distributions in vertical soil cross sections of the Chernobyl NPP 30-kilometer zone along the western fallout track. III. Soddy-podzolic soil, turf

Radionuclide distributions in vertical cross sections taken in soddy-podzolic soil and in turf along the western fallout track 5 km from the fourth block of the Chernobyl NPP are studied. The decrease of the content of all radionuclides with depth in the soddy-podzolic soil in the range 1-2 cm is constant with time (1987-1990) and is described to a first approximation by a semilogarithmic dependence of the specific activity on depth. The vertical radionuclide distributions change with increasing depth depending on the nature of the radionuclide. The main portion of the radionuclides (≥90%) are concentrated in the range 0-2 cm. In turf, the decrease of the radionuclide contents in the cross-sectional layers with depth deviates from the semilogarithmic dependence. Each radionuclide exhibits a unique change with depth of its content in the cross-sectional layers. The radionuclides penetrate to greater depths than in cross sections taken in soddy-podzolic soil. Thus, only 40% of the radionuclides of their amount in the whole cross section is contained in the 0-2 cm layer in 1990