Residence half-times of 137Cs in undisturbed surface soil in Nigeria based on measured soil concentration profiles.

摘要

The transport of fallout 137 Cs ? within the Nigerian soil has been studied in this paper by a compartment ? model. The measured concentrations of the radionuclide in the soil layers were examined by the model in order to estimate the transport parameters of residence half-time and the migration velocity of the radionuclide in the soils. The residence half-times were observed to be short and decreased with soil depth with a ? mean ranging from 0.3 years at 0 – 2cm soil depth in Akure site to 1.4 years at 10-15cm depth in Igbeti site. ? The migration velocity ? , calculated from the residence times with the consideration of the different thicknesses of the layers were observed to decrease slowly with depth at all the sampling sites with a range from 3.62 cm y -1 at Igbeti site to 8.21 cm.y -1 at Ikogosi site. The migration velocities obtained are quite higher than those reported in literature for global fallout.