Environmental Radiology of Southern Part of Zamfara State, Nigeria

The activity concentrations of the naturally occurring radionuclide for the soil samples collected from Southern Zamfara State were measured using Hyper-pure Germanium detector (HPGe). The terrestrial gamma radiation doses were measured using inspector alert, model 35448 manufactured by U.S.A from 250 locations across southern Zamfara. The mean activity concentrations of²²⁶Ra, ²³²Th and ⁴⁰K in the soil samples were found to be 55 Bqkg^-1, 35 Bqkg^-1 and 267 Bqkg^-1, respectively. The activity concentration of²³²Th, and ⁴⁰K obtained are within the recommended values of 45 Bqkg^-1 and 420 Bqkg^-1, while ²²⁶Ra concentration 55Bqkg^-1is higher than the world average value of 32 Bqkg^-1. The annual effective dose (AED), external  and internal  hazard index and Gamma representative index were computed as 0.07 μSvy^-1, 0.33, 0.98 and 0.81, respectively. The values are within the recommended safe limit of unity. Other parameters such as annual gonadal dose equivalent, radium equivalent activity  and excess lifetime cancer risk were also computed as 390.61 μSvy^-1, 123.73 Bqkg^-1 and 0.34. The values obtained for annual gonadal dose equivalent and excess lifetime cancer risk are higher than the recommended values of 300 μSvy^-1 and 0.29, while radium equivalent activity  is lower than the safe limit 370 Bqkg^-1. The result implies that the gonadal values may have some effects on the reproductive organs of the people in the study area. But other radiation hazard parameters show that it is safe to use the soil in the study area for farming and other activities.