Assessment of radioactivity concentration in soil of some mining areas in Central Nasarawa State, Nigeria

Abstract

A study was conducted to determine 226Ra, 232Th, and 40K natural activity concentrations in surface soils/sediments of some mining areas in Central Nasarawa State Nigeria, using Sodium Iodide-Thallium Gamma  Spectroscopy. Seven major sites were identified from the highly mining areas of the zone and a total of twenty (21) samples were collected  throughout the whole accessible areas. From the analyzed samples, mean natural activity concentrations were determined and the results show 403.963±7.29 Bq/kg, 32.52±4.65 Bq/kg and 56.23±2.30 Bq/kg for 40K, 226Ra and 232Th respectively. The results obtained were a bit lower compare to the World average value, except for 232Th which is higher than the World average value with a difference of 20.23 Bq/kg. The evaluated annual mean effective dose is 0.04±2.7 mSv/yr. This is far less than the
annual dose limit for members of the public. The mean Radium equivalent activity is 141.56±7.2Bqkg-1. The average background radiation absorbed doses at the two spots are 5.81 ±0.08 mSv/y and 8.45±0.56 mSv/y. This is higher compare to worldwide average of 1mSvy-1 given by IAEA (1996) and
UNSCEAR (2000). This implies that the people near the mining sites are likely to receive little or no radiation dose when the stay outside or inside their houses.

Keywords: Effective Dose, Background Radiation, Gamma Spectroscopy, Public, Mining Spot.