PAPER TITLE :EVALUATION OF NATURALLY OCCURRING RADIONUCLIDE IN SOIL SAMPLES FROM SARKIN PAWA MINING SITES IN NIGER STATE, NIGERIA.

JOURNAL OF EARTH AND ATMOSPHERIC RESEARCH | VOLUME 1 NUMBER 1 2018

Paper Details

  • Author(s) : 1Suleiman, I. K., 1AGU, M. N. and 1Onimisi M. Y.
  • Abstract:

This study presents results of Activity Concentrations, Absorbed dose rate and the Annual Effective dose
rates of naturally occurring radionuclides (40K, 232Th and 226Ra) absorbed in 8 soil samples collected from
different areas within the Sarkin Pawa mining sites in Niger State, North Central Nigeria. A laboratory γ-ray
spectrometry NaI (Tl) at the Centre for Energy Research and Training (CERT), Ahmadu Bello University
Zaria, was used to carry out the analysis of the soil samples. The values of Activity Concentration for 40K
ranged from 27.9938 ± 1.3997 to 986.4697 ± 10.5754; for 226Ra it ranged from 22.7115 ± 2.2016 to 128.6210
± 4.9826 BqKg-1 and for 232Th the ranged is from 16.3056 ± 1.7104 to 74.4583 ± 3.8769 Bq.Kg-1. While the
Absorbed Dose for 40K ranged from 1.1673±0.0647 to 41.1358 ± 0.4410 ?Gy.h-1, for 226Ra the range is from
10.4927 ± 1.0171 to 59.4229 ± 2.3020 ?Gy.h-1 and for 232Th range from 9.8486 ± 1.0331 to 44.9728 ± 2.3416 ?
Gy.h-1. The total average Absorbed Dose rate of the 7 soil samples collected is 96.6375 ?Gy.h-1 and the
estimated Annual Effective Dose for the sampled areas range from 0.0264- 0.1425 mSvy-1 (i.e. 26 – 143
μSv.y-1), with an average Annual Effective Dose of 0.1185 mSv.y-1 (i.e. 118.5μSv.y-1). These results show's
that the radiation exposure level reaching members of the public in the study areas is lower than the
recommended limit value of 1 mSv.y-1 (UNSCEAR, 2000). Also, the mean Radium Equivalents obtained
ranged from 48.1840 BqKg-1 (SP1) to 247.5553 BqKg-1 (SP3). These results show that the recommended
Radium Equivalent Concentration is < 370 BqKg-1 which is the requirement for soil materials to be used for
dwellings, this implies that the soil from this site is suitable use for residential buildings. The mean External
Hazard Index (H ) ranged from 0.1302 Bqkg-1 (SP1) to 0.6686 Bqkg-1 (SP3). While the maximum allowed ext-value
of (H = 1) corresponds to the upper limit of Ra (370 BqKg-1) in order to limit the external gamma ext eq
radiation dose from the soil materials to 1.5mGy y-1. That is, this index should be equal to or less than unity
(H ) ranged from 0.1916 Bqkg-1 (SP1) to 0.9766 Bqkg-1 (SP2) .Finally, the mean value of the Excess Alpha ext
Radiation (I ) ranged from 0.1136 Bq.Kg-1 (SP1) to 0.6431 Bq.Kg-1 (PA1). All these values for I are below the α α
maximum permissible value of I = 1 which corresponds to 200 Bq.Kg-1. It can, therefore, be said that no α radiological hazard is envisaged to dwellers of the study areas and the miners working on those sites area.

JOURNAL OF EARTH AND ATMOSPHERIC RESEARCH