Distribution of Natural Radionuclides in Ama Fatma Oil Shale, Morocco

• Published in: Engineering proceedings 2023-11, Vol.56 (1), p.229
• Main Authors: Samira El Aouidi, Nezha Mejjad, Azzouz Benkdad, Abdelmourhit Laissaoui, Moncef Benmansour, Said Fakhi
• Format: Article
• Language: English
• Subjects: Ama Fatma oil shale; gamma spectrometry; natural radioactivity; specific activities ratios
• ISSN: 2673-4591
• DOI: 10.3390/ASEC2023-15981

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−1 and those of Th-232 fluctuated between 1.48 ± 0.92 and 9.47 ± 1.06 Bq.kg−1. The measured concentrations for Ra-226, Pb-214, and K-40 oscillated between 33 ± 5 and 138 ± 9 Bq.kg−1, 18 ± 1 and 68 ± 3 Bq.kg−1, and between 17 ± 4 and 279 ± 16 Bq.kg−1, 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 232Th/238U and 226Ra/238U allowed an understanding of these radionuclides’ behaviors. The ratios 226Ra/238U 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.