NATURAL RADIOACTIVITY AND ASSOCIATED RADIATION HAZARDS IN SOIL OF PIMAK AND FARIN-DUTSE TIN MINES, WESTERN NASARAWA STATE, NIGERIA

Abstract

Radiological effects were carried out in the soil of the Farin-Dutse and Pimak mining sites in western Nasarawa State as a result of both internal and external exposure to radiation from natural sources related to 226Ra, 232Th, and 40K radionuclides. The activity concentrations of Ra, Th, and K activities in soil samples were measured using the sodium iodide thallium activated (NaI(Tl)) gamma detector. The activity concentrations of Ra, Th, and K for Farin-Dutse and Pimak were found to be within the range of 11 - 57 Bq kg^-1, 9 - 40 Bq kg^-1, and 434 - 856 Bq kg^-1; 12 - 42 Bq kg^-1, 27 - 63 Bq kg^-1, and 186 - 2086 Bq kg^-1 respectively; the potassium concentrations were found to be increasing with depth in all the locations and higher than the recommended limit except for Pimak1(0ft) and Pimak1 (1ft) respectively as reported by United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR 2000). The annual gonadal dose equivalent (AGDE), annual effective dose rate (AEDE), radium equivalent (Raeq), and absorbed dose rate (DR) were the radiological health hazards indicators for Farin-Dutse and Pimak were found to be within the range of 0.21- 0.56 mSv yr-1, 0.35 – 0.97 mSv yr-1, 338 - 752 Bq kg^-1, and 29 - 79 nGy hr-1; 0.34 – 0.83 mSv yr-1,0.60 – 1.39 mS yr-1, 237 - 1657 Bq kg^-1, and 49 - 113 nGy hr-1  respectively.