Jornal de Riscos Ambientais

Natural Radionuclides Levels and their Geochemical Characteristics of Abu Dabbab Albite Granite Mining Area, Central Nubian Shield of Egypt

Abstract

Mohamed Th. S Heikal, Mohamed Abd El Monsef, Saleh R Goma, Medhat M El Mansi and Gulcan Top

The present work addressed the natural radionuclides distribution and their geochemical characteristics for 21 albite granite samples, including surface, adit and subsurface core samples from Gebel Abu Dabbab rare metal-bearing albite granite (650-550 Ma). The measurements are provided by γ-ray spectroscopic analysis, including portable RS-230 model hand-detector and High Purity Germanium (HPGe) spectrometry. Chemical analysis using ICP-OES & ICP-MS have been carried out to determine the concentrations of major oxides and trace elements including U, Th (ppm) and 40K % for the studied rocks. With respect to the field spectrometric measurements, the average radionuclide concentrations for point samples of eU, eTh (ppm) and K% were 10.36, 19.46 and 3.48 respectively. Gamma ray HPGe detector indicates that the average specific activities of 238U, 232Th and 40K were 66.75, 29.97 and 641.68 Bq/kg for surface samples, respectively, 87.6, 57.3 and 329.4 Bq/kg for adit samples respectively, 87.3, 31.6 and 3.9 Bq/kg for subsurface core samples respectively. The average ratio is of 226Ra/ 238U<1 indicating enrichment in 238U due to its redistribution and remobilization. Regarding the chemical analysis for U, Th (ppm) and K%, the average concentrations were 6.90, 17.21 and 1.32 for surface samples as well as 8.33, 27.65 and 1.13 for adit samples, whereas the average concentrations of U, Th (ppm) and K% for the subsurface core samples were 4.85, 9.55 and 1.33 respectively. The radiometric, chemical data and the calculated P and D-factors of the studied radionuclides in Abu Dabbab rare metal-bearing albite granite confirmed that the redistribution of the radionuclides was formed later by hydrothermal Na-metasomatic albitization. All values of the radiation hazard indices in the studied samples of Abu Dabbab mining area are under the health hazard limits.