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

  •  Isaac Ajayi    


The transport of fallout 137Cs  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.

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