Baseline Measurements of Natural Radioactivity in Soil Samples from the Federal University of Technology, Owerri, South-East, Nigeria

Abstract

Aims: To determine the gamma dose rates and radionuclide concentration levels in soil samples from the Federal University of Technology, Owerri, Nigeria. Study Design: Sixty (60) soil samples were collected at different locations in the Federal University of Technology, Owerri, Nigeria. Each prepared sample was placed symmetrically on top of a lead-shielded NaI (Tl) detector for measurement. Place and Duration of Study: Federal University of Technology, Owerri, Nigeria, between April 2013 and October 2013. Methodology: A γ-ray spectrometry in the Radiation and Health Physics Research Laboratory, University of Ibadan, Nigeria was employed to carry out the radioactivity measurement of the 60 soil samples. The activity concentrations, absorbed dose rate in air as well as annual effective dose equivalent were calculated. Results: The activity concentrations of 40K, 226Ra and 232Th ranged from 21.90±1.62Bqkg-1 – 142.45±1.37Bqkg-1, < 3.65Bqkg-1 - 36.01±2.25Bqkg-1 and <4.43Bqkg-1 – 43.87±0.75Bqkg-1 respectively. The average absorbed dose rate was calculated as 25.99±8.35nGyh-1 while the annual effective dose equivalent ranged between 9.39µSvy-1 and 56.83µSvy-1 with an average of 31.89±10.25µSvy-1. These values are less than the world average values of absorbed and effective doses which are 51nGyh-1 and 70µSvy-1 respectively. Conclusion: Human activities and the presence of radioactive minerals on the campus of the Federal University of Technology, Owerri, Nigeria have not increased the radionuclide concentrations in the University environment beyond safety limit.