ASSESSMENT OF NATURAL RADIATION LEVELS IN SIWA OASIS, WESTERN DESERT

Abstract

A survey was conducted to determine the activity concentrations of 226Ra, 232Th (228Ra) and 40K and related external and internal radiation health hazard indices in water and soil of Siwa Oasis, Western Desert of Egypt. A total of 59 water and 58 soil samples were collected. The presence of natural radionuclides subsequently being assessed by HPGe γ-ray spectrometry. The obtained data were statistically treated by applying regression analysis, Pearson correlation and cluster analysis to investigate the influence of physico-chemical parameters on the distribution of the examined radionuclides in water and soil samples. It was found that all the Nubian Sandstone Aquifer System (NSAS) water samples have 226Ra and combined 226Ra and 228Ra activity concentrations values higher than the recommended level for drinking water. On the other hand, the activity concentrations of 40K in 67.79 % of the collected samples higher than recommended level for safe drinking water. For cultivated and uncultivated soil types, the activity concentrations of the radionuclide have the order of 40K > 226Ra > 232Th. The mean values of 226Ra, 232Th and 40K were 27.55 ± 1.79, 16.24 ± 2.49 and 254.22 ± 13.44 Bq kg-1; respectively for the cultivated soils and 15.08 ± 1.03, 10.32 ± 0.70 and 130.20 ± 6.90 Bq kg-1; respectively for the uncultivated soils.