Natural Isotopic Activity Ratios as Evidence of Migration and Leaching of Uranium in Egyptian Granitic Rocks

Abstract Gamma-spectrometry was utilized to analyse radionuclides in granitic rocks from the El Eridiya area through radiometric measurements. The activity concentration of 238 U ranges from 3493±83 to 5209±104 Bq kg −1 , while for 234 U and its isotope ( 235 U), it varies from 957±32 to 1012±34 Bq kg −1 and 153.0±4.5 to 256.0±5.5 Bq kg −1 , respectively. However, for the isotopes 230 Th and 232 Th, the range is from 11217±254 to 16291±305 Bq kg −1 and 31.0±1.1 to 85.3±0.5 Bq kg −1 , respectively. The activity concentration of 40K ranged from 67.9±1.6 to 109.0±2.1 Bq kg −1 . The ratios of 234 U/ 238 U in the studied granitic rock samples vary from 0.21±0.01 to 0.54±0.03. Due to the current oxidising conditions, most of the rock samples show a higher presence of 234 U compared to 238 U, with 234 U/ 238 U activity ratios below one. Additionally, the activity ratios of 232 Th/ 238 U range from 0.006 to 0.019 in the granitic rock samples from the El Eridiya area. Figures 3 and 4 display uranium enrichment, with all samples showing 232 Th/ 238 U ratios below one for the earth’s crust. Additionally, all samples showed 230 Th/ 238 U and 230 Th/ 234 U activity levels above one, suggesting preferential leaching of uranium in an oxygen-rich setting. Similarly, the 234 U/ 238 U and 230 Th/2 38 U activity ratios are below and above one, indicating U-leaching and U-accumulation, respectively. Figure 3 and 4 show uranium enrichment, with all samples having 232 Th/ 238 U activity ratios below one for the earth’s crust. There were benefits to uranium leaching in an environment with oxidation in all samples, with 230 Th/ 238 U and 230 Th/ 234 U activity ratios exceeding one. If the 234 U/ 238 U activity ratio is lower than one but the 230 Th/ 238 U activity ratio is higher than 1, it suggests U-leaching; if the 234 U/ 238 U activity ratio is greater than one and the 230 Th/ 238 U activity ratio is less than 1, it suggests U-accumulation.