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The study measured the activity concentrations of various radionuclides (238U, 234U, 230Th, 226Ra, 222Rn, 232Th, 40K, and 235U) using γ-ray spectrometry in 11 black shale samples from three trenches and a wall in Budaa area, southwestern Sinai, Egypt. The samples were taken from different parts of Magharet El Meyiah Formation (top, middle, and base) to understand radionuclide migration processes. The average activity concentrations of 238U, 232Th, and 226Ra in all samples were higher than the worldwide averages, while 40K levels were lower. Isotopic ratio relationships showed accumulation of radionuclides in most samples except one sample lies in uranium leaching sector from the base layer of the wall. Uranium–Thorium (U–Th) dating revealed varying ages of uranium deposition: 42.43–119.90 ka in trench 1, 40.09–85.37 ka in trench 3, 63.92 ka in trench 2, and 106.50 and 325.80 ka in the top of wall, suggesting differential mobility of uranium. Hazard parameters like external radiation hazards (Hex < 1) were minimal and annual effective dose rates within acceptable limits, while, internal radiation hazards (Hin > 1) were a concern for samples from the top layers. All samples had absorbed dose rates higher than the global average, indicating elevated background radiation levels. [ABSTRACT FROM AUTHOR]

Yellow ochre is the basic material used in the manufacture of yellow oxide (a commercial product). Yellow ochre samples were taken from three different formations in southwestern Sinai: Abu Hamata, Um Bogma, and Abu Zarab. Yellow ochre occasionally exists in Abu Hamata Formation particularly in El Ferah area, associated with Fe–Mn ore in Wadi El Sahu (Um Bogma Formation) and in Himayer area (Abu Zarab Formation). The XRD analysis of the raw material reveals that they are mainly composed of goethite, which is associated with quartz and kaolinite in El Ferah area, hematite, kaolinite and quartz in Himayer area, and kaolinite, gypsum and quartz in Wadi El Sahu. The commercial product is mainly composed of goethite, quartz, and calcite. The heavy mineral investigation shows that some yellow ochre samples contain zircon and rare earth sulfate which may be responsible for the radioactivity of ochre due to their thorium and uranium content. The average values of specific radio-activities of most radionuclides in the samples of Himayer area I and II, and El Sahu I are higher than the respective world averages, while their activities are lower in El Ferah and El Sahu II. Th/U and Ra/U ratios exhibit vigorous changes in physico-chemical conditions during uranium leaching and deposition. Most of the radiological parameters in the ferruginous sediment and commercial product samples from El Ferah, El Sahu II, and Himayer II are lower than the recommended international values but higher than those from Himayer I and El Sahu I samples. The plotted hierarchical cluster analysis (HCA) exhibits that the main contributors for the hazards of these sediments and their commercial product are 238U, 232Th and 226Ra in Himayer I &II, commercial products, and El Ferah area, 232Th and 226Ra in El Sahu II , 232Th, 40K and 226Ra in El Sahu I. [ABSTRACT FROM AUTHOR]

With the wide use of radioactive materials, it is important to look for locally available and inexpensive materials to serve as efficient absorbers, suitable for shielding against radiation hazards. Due to its widespread availability and affordability, natural bentonitic shale is a viable option for use as a nuclear shielding material. In this study, natural bentonitic samples were cut into cylindrical pellets of varying thicknesses. The chemical composition of the natural bentonitic shale samples was determined through the use of X-Ray Fluorescence (XRF) spectroscopy. The linear and mass attenuation coefficients of bentonitic samples were evaluated using a NaI(Tl) scintillation detector at 662 keV energy of 137Cs, as well as at 1,173 keV and 1,332 keV energies of 60Co, gamma-ray sources. The experimental results indicated that bentonitic samples B3 and M2 exhibited superior shielding parameters compared to other bentonitic samples, attributable to their elevated densities. These two samples are distinguished by a high CaO content and a low AL2O3 content. Furthermore, the Half Value Layer (HVL), Tenth Value Layer (TVL), and mean free path thicknesses were calculated at these energies using linear attenuation coefficients. The theoretical mass attenuation coefficient, calculated with the assistance of the XCOM program and experimental estimates, was found to be in good agreement with the theoretical value. [ABSTRACT FROM AUTHOR]

Humans benefit from nuclear technology, but it also generates nuclear radiation that is bad for both the environment and human health. The serious issue of radiation leakage affects many technological applications. Shielding is required to protect both users and the environment from negative side effects. This work describes the radioactive attenuation properties of some natural rocks, such as claystone, bentonitic claystone, bentonitic shale, sandstone, and basalt using a NaI(Tl) detector. The mass attenuation coefficients μ m of these rocks at various photon energies, half-value layer (HVL), tenth-value layer (TVL), and mean free path (MFP) were determined. The validation of obtained values of μ m was carried out against the theoretical calculations from the XCOM program, and the correlation factor and relative deviation between the two methods were evaluated. It was noted that basalt samples exhibit superior shielding parameters when compared to other rock samples. Also, the concentrations of naturally occurring radioactive elements (238U, 226Ra, 232Th, and 40K) were measured, allowing for the calculation of environmental hazard indices and assessment of attenuation (%) efficiency for certain natural rocks, such as bentonite, sandstone, and basalt. The results revealed that increasing the thickness of Basalt-AZ from 1.5 cm to 2 cm results in an approximate 11% rise in attenuation percentage, with values reaching 77.12%, 67.2%, 67.65%, and 59.8% for NMA-U, IAEA-Th, IAEA-Ra, and IAEA-K, respectively. [ABSTRACT FROM AUTHOR]

The main concern of this study is to test the ability of some fungi isolated from Sinai Peninsula carbonaceous shales to perform microbial leaching of rare earth elements (REEs) from these rocks. Two methods of REEs bioleaching were tested using both direct (active) and indirect (passive) processes. Direct bioleaching process of carbonaceous shale samples was found to be more effective than indirect process for all tested microorganisms. Bioleaching efficiency of REEs using different fungal strains increases with decreasing REEs concentrations when their growth rate decreases. Strains of Aspergillus (A. niger and A. flavus) were found to be the most efficient organisms. The maximum extraction yield of total REEs was 86% at 7days incubation time, 1% pulp density, and 30 °C incubation temperature. A. niger and A. flavus exhibit good potential in generating a variety of organic acids (citric and oxalic) effective for REEs solubilization. Citric and oxalic acids contents produced by A. niger was higher than by A. flavus interpreting higher REEs bioleaching efficiency of A. niger than A. flavus. From properly prepared pregnant bio-leach liquor, the leached REEs were recovered in the form of REEs oxalate product using classical chemical technique. [ABSTRACT FROM AUTHOR]