Evaluation of the 137Cs activity-depth profiles by the diffusion-convection model
International Journal of Physical Sciences
Deparment of Physics and Electronics, Adekunle Ajasin University Akungba-Akoko, Ondo State, Nigeria; Department of Physics, University of Cape Town, South Africa
Ajayi, I.R., Deparment of Physics and Electronics, Adekunle Ajasin University Akungba-Akoko, Ondo State, Nigeria; Raji, A.T., Department of Physics, University of Cape Town, South Africa
The diffusion-convection model of 137Cs transport has been used to evaluate the activity-depth profiles of soils in southwestern Nigeria in this study. The experimentally determined depth profiles were fitted into the diffusion-convection equation to obtain the diffusion coefficient D and the convective velocity u. Results obtained showed that the range of the diffusion coefficient was 0.72 - 1.02 cm2 per year while that of the convective velocity was from 0.07 to 0.16 cm per year. It was observed that the diffusion coefficient is higher than the convective velocity in all the sampling points. The low convective velocities obtained in all the locations may imply that convective rates of the radionuclide within the soil layers are insignificant compared to the diffusion rates. © 2010 Academic Journals.
137Cs activity; Convective velocity; Diffusion coefficient; Radionuclide; Soil depth