Assessment of natural and anthropogenic radioactivity levels in rocks and soils in the environments of Juban town in Yemen

The natural radioactivities of K-40, Ra-226, and Th-232 and the fallout of Cs-137 in rock and soil samples collected around Juban town in Yemen (south west of Asia) were measured. Concentrations of radionuclides in samples were determined by gamma-ray spectrometer using HPGe detector with specially designed shield. The average radioactivity concentrations of Ra-226, Th-232, and K-40 were determined expressed in Bq/kg. The results show that these radionuclides were present in concentrations of (53.6 +/- 4, 127 +/- 6.7, and 1742.8 +/- 62 Bq/kg), (55 +/- 4, 121 +/- 6.6, and 2341 +/- 78 Bq/kg), (212.8 +/- 8.7, 109 +/- 5.5, and 32.4 +/- 4.7 Bq/kg), and (32.1 +/- 3, 22.3 +/- 2.9 and 190.9 +/- 15 Bq/kg) for granite, gneiss, siltstone, and sandstone rocks, respectively. For soil the corresponding values were 44.4 +/- 4.5, 58.2 +/- 5.1, and 822.7 +/- 31 Bq/kg. Low deposits of Cs-137 were noted in investigation area, where the activity concentrations ranged from 0.1 +/- 0.1 to 23.2 +/- 1.2 Bq/kg. Also the radiological hazard of the natural radionuclides content, radium equivalent activity, total dose rates, external hazard index, and gamma activity concentration index of the (rocks/soils) samples in the area under consideration were calculated. The data were discussed and compared with those given in the literature. (C) 2011 Elsevier Ltd. All tights reserved.