Natural Radioactivity in Carbonate Rocks Outcropping at Al-Lajjun Region, South Jordan by Gamma-Ray Spectroscopy

Author(s): Mahmoud Abu-Kharma, Sokainah Rawashdeh, Tayel El-Hasan

Soil samples were collected from the Al-Lajjun area near the dam and analyzed for activity concentrations of primordial radionuclides using gamma-ray spectrometry. A low background configuration pure germanium (HPGe) detector was used for this purpose. The mean activity concentrations for ⁴⁰K, ²²⁶Ra (²³⁸U), ²³²Th, ²³⁸U, and ²³⁵U at the location of Al-Lajjun Dam at Al-Karak Governorate in central Jordan were found to be in the range of 12-560, 234-6037, 4.3-28.4, 459-54147, and 43102- 3656 Bq/Kg, respectively. Some of the obtained values were much higher than the world average values, except for ⁴⁰K and ²³²Th.

To assess the radiological risk, radium equivalent activity, absorbed dose rate, and annual effective dose equivalent were calculated. The external hazard value (Hex) ranged from 0.638 to 16.316, which indicates significant activity in certain locations. In this study, the concentration of ²³⁸U was found to be much higher than the acceptable value reported by UNSCEAR-2000. Therefore, cautionary measures with intense and continuous monitoring should be implemented for the dam site and water. Therefore, cautionary measures with intense and continuous monitoring should be implemented to the dam site and water.