Assessment of terrestrial naturally occurring radioactive Material in soil and mine tailings of Awo and Ede, Osun-State, Nigeria.

Abstract

The levels of natural radioactivity of ⁴⁰K, ²³⁸U and ²³²Th in soils and mine tailings of Awo and Ede areas of Osunstate, Nigeria have been measured using a portable, advanced survey meter 992 Fluke Victoreen Gamma Scout Model for in-situ investigation and a 1 inch by 1 inch Cesium Iodide detector system. The specific activities of ⁴⁰K varied from 316.67±14.23 Bq kg^-1 to 1487.35±3.03 Bq kg^-1  with a mean value of 620.05±9.57 Bq kg^-1  ; for 238U, 13.11±2.36 Bq kg^-1  to 88.26±3.03 Bq kg^-1 with a mean value of 27.50±3.14 Bq kg^-1 ; and for 232Th, 9.26±1.00 Bq kg^-1  to 55.81±2.99 Bq kg^-1 with a mean value of 18.26±2.17 Bq kg^-1. The mean values obtained for Absorbed Dose rate and External Hazard Index (Hex) were 48.12 nGyhr^-1  and 0.26 respectively. Generally, with the exception of ⁴⁰K, the activity levels of the radionuclide investigated were low and within the world average values. The calculated hazard indices were lower than internationally recommended limits.

 Keywords: Mining, NORMs, Hazards, Gamma Spectrometry