Background Radiation Measurement and the Assessment of Radiological Impacts due to Natural Radioactivity Around Itakpe Iron-Ore Mines

Mining activity and metal extraction processes have been identified as one of the major pathways through which natural radionuclides are accumulated in the terrestrial environment. Exposure to excessive radiation from natural radionuclides can cause deleterious health hazards to man. In this study therefore, the activity concentrations of primordial radionuclides (K-40, U-238 and Th-232) were measured in rock, soil, tailings and water samples collected from abandoned iron ore mines in order to estimate the radiological impacts associated with the previous mining and metal extraction activities within the environment of abandoned Itakpe iron-ore mines. Gamma spectrometry utilizing a well calibrated NaI(Tl) detector was employed for the measurements. Results show that the average activity concentrations of K-40, U-238 and Th-232 are 1084 +/- 581, 11.0 +/- 7.7 and 5.0 +/- 1.8 Bq kg(-1) respectively for rock samples and 415.6 +/- 197.5, 12.8 +/- 5.7 and 8.8 +/- 5.8 Bq kg(-1), respectively for soil samples. The activity concentrations of the three radionuclides are much lower in water samples compared to rocks and soil. Radiological hazard indices calculated from the activity concentrations show that the mining activities have little or no negative impacts on the environment as the radiological risk indices obtained are all lower than their permissible limits.