Assessment of Radiological Hazards Associated with Zumba Mining Sites in Niger State, Nigeria

Abstract

The assessment of radiological associated with Zumba mining sites in Niger State was was carried out using NaI(Tl)  gamma ray spectroscopy. The results shows mean activity concentrations ⁴⁰K ²²⁶ , Ra and ²³²Th is  197.2449 Bq.Kg^-1; 48.4357 Bq.Kg^-1 and 40.6581 respectively. The total mean for the absorbed dose rate of  all the 7 soil samples analysed is 46.0830 ŋGy.h^-1 and also the annual effective dose in the study areas ranged from 0.0342 - 0.0893 mSvy^-1 (i.e 34 – 89 μSv.y^-1), which had an mean annual effective dose of 0.0646 mSv.y^-1 ( ie 65μSv.y^-1). These results shows that the radiation exposure level for members of the public in the study areas is lower than the recommended limit value of 1 mSv.y^-1 (UNSCEAR, 2000). Furthermore, the mean external hazard index (H_ext) is 0.1694 Bqkg^-1 (ZB3) to 0.4269 Bqkg^-1 (ZB7), while its maximum allowed value is (H_ext = 1) which corresponds to upper limit of Ra_eq (370 BqKg^-1) in order to limit the external gamma radiation dose from the soil materials to 1.5 mGy y^-1. The accepted index value should be equal to or less than unity (H_ext  = 1). Therefore,  it can be deduce said that no radiological hazard is conceptualize to dwellers in the  study areas and the miners working on those mining sites. The entire environment is within the permissible dose limit for the workers of the mining sites and also for the agriculture and construction buildings. Therefore, the mining site is safe in terms of radiological hazards.