Quantification of Activity Concentrations and Radiation Hazard Indices in the Solid Minerals Exploration Fields of Benue State, Nigeria with Multivariate Statistical Approach

Abstract

The quantification of activity concentrations of radionuclides and the radiation hazard indices in the exploration fields of Benue State have been carried out. Samples of the environmental matrix (soil and minerals) were collected from five mining sites of barite, limestone, lead, coal and salt in Lessle, Gboko, Anyin, Owukpa and Akuana communities.  The concentrations of radioactivity was analyzed using NaI (Tl) γ-ray spectroscopy. Results showed that the concentrations of activity of the primordial radionuclides 40K, 238U, and 232Th for soil samples obtained ranged from 11.42 (Salt) – 1491.47 (Lead) Bq/kg, 12.87 (Barite) – 452.32 (Coal) Bq/kg and 6.78 (Coal)–108.41 (Barite) Bq/kg respectively. The mean value activity concentration of the radionuclides in the minerals samples at the mining sites were 10.58 – 623.36 Bq/kg, 1.97 – 540.33 Bq/kg and 2.13 – 25.28 Bq/kg for 40K, 238U, and 232Th respectively. The radium equivalent activity (Raeq), external hazard index, Hex, internal hazard index (Hin), representative index (Ig) and excess lifetime cancer risk calculated for soil and minerals samples compared  favourably with the precautionary limits set by UNSCEAR. The excess lifetime cancer risk estimated for soil which was fairly insignificant compared with 0.05 prescribed by ICRP for low level radiation. The multivariate statistical (Pearson’s correlation and cluster) analysis showed some positive significant among 40K, 238U and 232Th, and with other radiological parameters in some mine fields. The study indicated that the minerals and soil samples from the mining sites will pose no major health risk to the public if used for industrial activities except for the salt minerals consumption.