Evaluation of Naturally Occurring Radionuclide Materials in Soil Samples Collected From Some Mining Sites in Zamfara State, Nigeria
A. J. Innocent
Department of Physics, Nigerian Defence Academy, Kaduna, Nigeria.
M. Y. Onimisi *
Department of Physics, Nigerian Defence Academy, Kaduna, Nigeria.
S. A. Jonah
Centre for Energy Research and Training, Ahmadu Bello University, Zaria, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Aims: To identify and quantify prominent gamma emitting-NORMs associated with mining activities in Zamfara State, Nigeria.
Study Design: Soil samples were collected from 10 different mine sites in Zamfara State, northwest-Nigeria for gamma spectroscopy analysis.
Place and Duration of Study: Department of Physics, Nigerian Defence Academy Kaduna, Nigeria, between June 2012 and October 2012.
Methodology: A laboratory based γ-ray spectrometry NaI(Tl) at the Centre for Energy Research and Training (CERT), Ahmadu Bello University Zaria, Nigeria was employed to carry out the analysis of the soil samples.
Results: The values of activity concentration found for 40K, 238U and 232Th range from 227.10±7.54 – 590.44±10.57, 4.68±3.52 – 18.98±0.84 and 40.58±1.85 – 94.92±2.75 Bq.kg-1 respectively, while absorbed dose rate in the soil samples for 40K, 238U and 232Th range from 9.47±0.31 – 24.62±0.44, 2.16±1.62 – 8.77±0.39 and 24.51±1.12 – 57.33±1.66 nGy.h-1 respectively. The total average absorbed dose rate of the soil samples collected is 59.70 nGy.h-1 and the estimated annual effective dose for the study areas range from 52 – 106 μSv.y-1, with an average annual effective dose of 73 μSv.y-1.
Conclusion: The radiation exposure level for members of the public in the study areas is within the safety limit.
Keywords: Radionuclides, soil, mining, activity concentration, absorbed dose, Zamfara