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

Abstract Five soil profiles from a site about 8 km SE of the Chernobyl NPP were investigated for the vertical distribution of radionuclides. The average 137 Cs-inventory at the site is about 2.6 MBq/m 2 (reference date 1 May 1986). Apart from 137 Cs, the following radionuclides have been identified (their activity ratios to 137 Cs in brackets): 134 Cs (0.537), 125 Sb (0.068), 60 Co (0.0022), 154 Eu (0.016), 155 Eu (0.020), 94g Nb (9.5E-5), 239/240 Pu (0.0088), 238 Pu (0.040), 90 Sr (0.30) and 241 Am (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 cm 2 /a. The rankings of the velocities v for different radionuclides are (Sr, Cs, Sb, Co, Pu) D , the following rankings have been found: (Nb, Sr, Cs) p =0.1 level).