Assessment of radioactivity in Granitoids at Nikeiba, Southeastern Desert, Egypt; radionuclides concentrations and radiological hazard parameters

A review on radionuclide pollution in global soils with environmental and health hazards evaluation

Human populations are being exposed to a wide spectrum of radiation from soils as a result of the availability of radiation sources. Assessing the ecological and health effects of radionuclides in soils is crucial to support the optimal soil management practices but large-scale studies are limited. This study compiled data on radionuclides (226Ra, 232Th, 40K, 238U, and 137Cs) in soils located across the world (44 countries and 159 places) between 2008 and 2022 and applied radiological hazards indices and several multivariate statistical approaches. The average activity concentration (Bq/kg) of 226Ra, 232Th, 40K, 238U, and 137Cs were 408.56, 144.80, 508.78, 532.78, and 83.12, respectively, whereas 226Ra, 232Th, 40K, and 238U exceeded the standard limits. The principal component analysis explained more than 91% of variation in soils. Based on the geoaccumulation index, 40K posed moderately to heavy contamination whereas 238U and 226Ra posed moderate contamination in soils. Moreover, the mean values of radiological hazards evaluation such as radium equivalent activity (487.17 Bq/kg), external radiation hazard indices (1.32), internal hazard indices (2.15), absorbed dose rate (247.86 nGyh-1), annual effective dose rate (1.82 mSvy-1), activity utilization index (4.54) and excess lifetime cancer risk (63.84 × 10-4) were higher than recommended limit suggesting significant radiological risks in study region soils. The findings indicated that the study area soils were contaminated by radionuclides and unsafe for hazards in terms of the health risks linked with studied radioactive contents. The study is valuable for mapping radioactivity across the globe to determine the level of radioactivity hazards.

Assessment of the potential radiation hazards posed by Nubian sandstone, Egypt

The study found that the activity concentrations of the radionuclides 238U, 232Th and 40K in the sandstone are 32 ± 13, 29.6 ± 12.2, and 132.6 ± 86.4 Bq kg-1, respectively. These values are lower than the reported worldwide limits of 33, 45, and 412 Bq kg-1. According to the present study, the absorbed dose rate (Dair), the annual effective dose, and the excess life time cancer were all found to be below the worldwide mean. Pearson correlation, PCA, and HCA were used to analyze the data and identify patterns in the relationship between radionuclides and radiological hazards. A statistical analysis of the sandstones showed that the radioactive elements 238U, 232Th and 40K are the main contributors to the radioactive risk. The study suggests that the sandstone is safe to use. The levels of radioactivity are not high enough to pose a risk to human health.

Environmental risk assessment associated with acidic volcanics in Egypt

The present work aims to study gamma rays emitted by radionuclides such as ²³⁸U, ²³²Th and ⁴⁰K from acidic Monqul volcanics. The studied volcanics are represented by a thick stratified lava flows interbanded with their pyroclastics. They are composed of thick lava flows of andesite and, to a lesser extent of basalt, and acidic volcanics including rhyolite and dacite. The average values of ²³⁸U, ²³²Th and ⁴⁰K are (46 ± 24 Bq kg^-1), (62 ± 11 Bq kg^-1) and (1227 ± 318 Bq kg^-1) in the rhyolite-dacite samples are greater than the worldwide average. The variation of radioactive bearing minerals observed inside granite faults produced the great amounts of radioactivity perceived in the samples. Calculating radiological risks is used to assess the public's radioactive risk from radionuclides revealed in the studied Rhyolite-dacite samples. The acceptable limit for excess lifetime cancer (ELCR) evaluations has been exceeded. As a result, Rhyolite-dacite are inappropriate for apply in building materials.

Natural Radioactivity and Radiological Hazard Effects from Granite Rocks in the Gabal Qash Amir Area, South Eastern Desert, Egypt

The existence of radioactivity linked to the heavy-bearing minerals in building materials—such as granite—has increased attention to the extraction procedure. Granite rocks play an essential economic role in various areas of Egypt. Thus, this study intended to detect the 238U, 232Th, and 40K activity concentrations in the examined granite samples and to determine the corresponding radiological risks associated with the granite. The studied rocks were collected in the Gabal Qash Amir area (south Eastern Desert, Egypt). The obtained results of the activity concentrations for 238U (193 ± 268) Bq/kg, 232Th (63 ± 29) Bq/kg, and 40K (1034 ± 382) Bq/kg indicated that there were moderate concentrations in the investigated samples, which were greater than the worldwide average. The radioactivity levels in the studied granite samples are due to the secondary alteration of radioactive-bearing minerals associated with cracks of granites (secondary minerals in muscovite granites are wolframite, uraninite, uranophane, beta-uranophane, autunite, xenotime, columbite, zircon, and monazite). The radiological risk assessment for the public from the radionuclides that were associated with the studied granite samples was predicted via estimating the radiological hazard factors, such as the radium equivalent content (362 Bq kg−1), compared with the recommended limit. The dosing rate Dair in the air (169.2 nGy/h), the annual effective dose both outdoors (AEDout ~ 0.21 ± 0.17 mSv) and indoors (AEDin ~ 0.83 ± 0.67 mSv), the annual gonadal dose equivalent (AGDE ~ 1.18 ± 0.92 mSv), as well as the external (Hex) and internal (Hin) hazard indices (>1), and another factor were associated with excess lifetime cancer risk. According to the statistical investigation, the studied granites were inappropriate for use in construction and infrastructure fields. They may induce health problems due to the radioactivity levels, which exceed the recommended limits.

Cancer Risk Assessment and Geochemical Features of Granitoids at Nikeiba, Southeastern Desert, Egypt

Different rock types (syenogranite, alkali feldspar granite and quartz syenite intruded by microgranite dikes and quartz veins) were investigated in the Nikeiba region in Egypt. The main components of the studied intrusive rocks, comprised of granites and quartz syenite, are plagioclase, amphibole, biotite, quartz and K-feldspar in different proportions. Ground gamma ray measurements show that syenogranite, quartz syenite and microgranite dikes have the highest radioactivity (K, eU, eTh and their ratios) in comparison with alkali feldspar granite. Geochemically, syenogranite, alkali feldspar granite and quartz syenite are enriched with large-ion lithophile elements (LILE; Ba, Rb, Sr) and high field-strength elements (HFSE; Y, Zr and Nb), but have decreased Ce, reflecting their alkaline affinity. These rocks reveal calc–alkaline affinity, metaluminous characteristics, A-type granites and post-collision geochemical signatures, which indicates emplacement in within-plate environments under an extensional regime. U and Th are increased in syenogranite and quartz syenite, whereas alkali feldspar granite shows a marked decrease in U and Th. The highest average values of AU (131 ± 49 Bq·kg−1), ATh (164 ± 35) and AK (1402 ± 239) in the syenogranite samples are higher than the recommended worldwide average. The radioactivity levels found in the samples are the result of the alteration of radioactive carrying minerals found inside granite faults. The public’s radioactive risk from the radionuclides found in the investigated granitoid samples is estimated by calculating radiological risks. The excess lifetime cancer (ELCR) values exceed the permissible limit. Therefore, the granitoids are unsuitable for use as infrastructure materials.