Depleted uranium residues, NORMs and 137Cs in the coastal zone soil of Musandam Peninsula, Hurmuz strait region, Sultanate of Oman

Abstract

Musandam peninsula located at one of the most important marine strait overlooking the Arabian/Parisian Gulf. Environmentally, this area is characterized by its primitivistic status and vulnerable to any natural or manmade disturbances. This work presents the second phase of a comprehensive radiation measurement in Musandam Peninsula environment amid to investigating the presences of depleted uranium (DU) residues and assessing the current levels of 226Ra, 228Ra, 40K and 137Cs in surface soil of coastal area. For this purpose, thirty representative soil samples were collected and analyzed for 235U using gamma rays spectrometry and for total U using ICP-OES techniques. Results revealed that the range of isotopic abundance of 235U was (0.70%–0.77%) with an average of 0.72%, confirming the detected uranium is naturally originated from the geological formations of investigated soil. Additionally, the values of Th/U ratios were calculated to be ranged from 0.37 to 1.95 with an average of 1.5 indicating the dominant geological formations are metamorphic sedimentary rocks that contain low levels of Th. The averages of radioactivity levels of NORMs indicated 16.02 Bqkg−1, 7.83 Bqkg−1 and 174.03 Bqkg−1 for 226Ra, 228Ra, and 40K respectively. The average of areal concentrations for 137Cs was 2481.5 Bqm−2 ranges from 1040 Bq/m2 to 9225 Bqm−2. The total external annual effective dose from all measured radionuclides was 23 μSv 237Cs contribution is 1% while 238U, 232Th series and 40K radionuclides contributions are 32%, 28% and 39% respectively. Radium equivalent, external, and internal radiation hazard indices indicate no radiological anomaly.