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Distribution of Natural Radionuclides in Ama Fatma Oil Shale, Morocco
oleh: Samira El Aouidi, Nezha Mejjad, Azzouz Benkdad, Abdelmourhit Laissaoui, Moncef Benmansour, Said Fakhi
Format: | Article |
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Diterbitkan: | MDPI AG 2023-11-01 |
Deskripsi
The present work aims to analyze the distribution of radionuclides naturally occurring in the oil shale of the Ama Fatma coastal zone. For this purpose, using gamma-ray spectrometry, we analyzed the activity concentrations of uranium (U), thorium (Th) series, and potassium-40 (K-40) in oil shale samples retrieved from the study area. The concentrations of U-238 ranged from 45 ± 36 to 194 ± 50 Bq.kg<sup>−1</sup> and those of Th-232 fluctuated between 1.48 ± 0.92 and 9.47 ± 1.06 Bq.kg<sup>−1</sup>. The measured concentrations for Ra-226, Pb-214, and K-40 oscillated between 33 ± 5 and 138 ± 9 Bq.kg<sup>−1</sup>, 18 ± 1 and 68 ± 3 Bq.kg<sup>−1</sup>, and between 17 ± 4 and 279 ± 16 Bq.kg<sup>−1</sup>, respectively. The obtained values variation appears to be related to the deposit nature and assimilation processes of appropriate radionuclides rather than the retrieved samples’ related depth. The analysis of <sup>232</sup>Th/<sup>238</sup>U and <sup>226</sup>Ra/<sup>238</sup>U allowed an understanding of these radionuclides’ behaviors. The ratios <sup>226</sup>Ra/<sup>238</sup>U ranged from 0.56 to 0.74 with a mean value of 0.70 which indicates the existence of disequilibrium in the investigated oil shale samples. This disequilibrium can be attributed to significant differences in the mobility of these radionuclides.