Vertical distribution of radionuclides in soil of a grassland site in Chernobyl exclusion zone

Five soil profiles from a site about 8 km SE of the Chernobyl NPP were investigated for the vertical distribution of radionuclides. The average 137Cs-inventory at the site is about 2.6 MBq/m2 (reference date 1 May 1986). Apart from 137Cs, the following radionuclides have been identified (their activity ratios to 137Cs in brackets): 134Cs (0.537), 125Sb (0.068), 60Co (0.0022), 154Eu (0.016), 155Eu (0.020), 94gNb (9.5E-5), 239/240Pu (0.0088), 238Pu (0.040), 90Sr (0.30) and 241Am (0.011). Apparent vertical migration velocities are between 0.14 and 0.26 cm/a, apparent dispersion coefficients range from 0.02 to 0.13 cm2/a. The rankings of the velocities v for different radionuclides are (Sr, Cs, Sb, Co, Pu)<Am<Eu and Sr<(Cs, Nb), for D, the following rankings have been found: (Nb, Sr, Cs)<Am<Eu, Cs<Sb and Nb<Co (all on p=0.1 level)