Assessment of radiological hazards from soil samples in the Northeastern area of Burkina Faso

Abstract

The activity concentrations of main naturally occurring radionuclides were determined with the aim of assessing the radiation hazards in the Northeastern part of Burkina Faso. Soil samples were taken and analyzed by the gamma-ray spectrometry method. The ranges of specific activity of 238U, 232Th and40K are 15.25 pm 2.59 , text{Bq} cdot {text{kg}^{-1}} to 109.57 pm 3.21 , text{Bq} cdot {text{kg}^{-1}}, 19.56 pm 1.65 , text{Bq} cdot {text{kg}^{-1}} to 44.88 pm 2.49 text{Bq} cdot {text{kg}^{-1}} and 125.74 pm 4.40 , text{Bq} cdot {text{kg}^{-1}} to 705.85 pm 10.79 , text{Bq} cdot {text{kg}^{-1}} respectively. Three high background radioactivity areas have been identified for Uranium, Thorium and Potassium on different places in the study area. The radiological hazards indices vary from 62.87 , text{Bq} cdot {text{kg}^{-1}} to 189.47 , text{Bq} cdot {text{kg}^{-1}} for the Radium equivalent activity (Ra_{eq}), 29.5 , eta text{Gy} cdot {text{h}^{-1}} to 86.65 , eta text{Gy} cdot {text{h}^{-1}} for the absorbed dose rate (D_R), 0.18 , text{mSv} cdot {text{y}^{-1}} to 0.53 , text{mSv} cdot {text{y}^{-1}} for the annual effective dose rate (AEDE), 0.21 to 0.81 for the internal hazard index (H_{in}), 0.17 to 0.51 for the external hazard index (H_{ex}), 1.27 times 10^{-4} to 3.73 times 10^{-4} for the Excess Lifetime Cancer Risk (ELCR) and 209.01{mkern 1mu} mu , 0.18{mkern 1mu} Sv cdot y^{{ - 1}} to 594.21 , mu text{Sv} cdot {text{y}^{-1}} for the annual gonadal dose equivalent. The average values of indices are well below their permissible limit. However, at Niapsi the obtained values for absorbed dose rate, annual effective dose rate and excess lifetime cancer risk are little above their permissible limit.