Volume 47, Number 2, Avril-Juin 2012
|Page(s)||243 - 252|
|Published online||04 July 2012|
Gamma radioactivity levels and their corresponding external exposure of soil samples from tantalite mining areas in Oke-Ogun, South-Western Nigeria
Department of Physical Sciences, Bells University of
2 Department of Physics, University of Ibadan, Nigeria
Accepted: 16 January 2012
The radioactivity concentrations of 226Ra, 232Th and 40K were measured using gamma-ray spectroscopy with NaI (Tl) detectors in four tantalite mining sites in the Oke-Ogun area, South-Western Nigeria. The measured values of the activities of 40K, 226Ra and 232Th in the soil samples were found to lie in the ranges 123.7 ± 3.8 – 1372.3 ± 8.6, 16.8 ± 1.6 – 71.1 ± 2.53 and 3.0 ± 0.7 – 31.9 ± 1.0 Bq kg–1, respectively. These samples were also found to have radium equivalent activity in the range 74.2–121.0 Bq kg-1. Values of 0.2–0.3 for the external and 0.3–0.4 for the internal hazard indices were estimated for the samples and the annual effective dose varied from 70.3 ± 13.5 to 100.8 ± 42.8 µSv with a mean of 87.5 ± 18.6 µSv y–1. The annual effective dose is higher than the world average.
Key words: Oke-Ogun / radionuclide / tantalite / natural radioactivity / effective dose
© EDP Sciences, 2012
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