Evaluation of heat generation by radioactive decay of sedimentary rocks in Eastern Desert and Nile Valley,Egypt

Radioactive heat-production (RHP) data of sedimentary outcrops in Gebel Anz (Eastern Desert) and Gebel Sarai (Nile Valley) are presented. A total of 103 rock samples were investigated, covering all major rock types of the areas. RHP were derived from uranium, thorium and potassium concentrations measured from gamma-radiation originating from the decay of ²¹⁴Bi (²³⁸U series), ²⁰⁸Tl (²³²Th series) and the primary decay of ⁴⁰K, obtained with a NaI (Tl) detector. The heat-production rate of Gebel Anz ranges from 0.94 (Nubai Sandstone ) to 5.22 μW m^?3 (Duwi Formation). In Gebel Sarai it varies from 0.82 (Esna Shale) to 7 μW m^?3 (Duwi Formation). The contribution due to U is about 62%, from Th is 34% and 4% from K in Gebel Anz. The corresponding values in Gebel Sarai are 69.6%, 26.9% and 3.5%, respectively. These data can be used to discuss the effects of the lateral variation of the RHP rate on the heat flux and the temperature fields in the upper crust.     

Determination of chromium and trace elements in El-Rubshi chromite from Eastern Desert,Egypt by neutron activation analysis

Neutron activation analysis (NAA) is one of the most powerful analytical techniques for multielement determination of rocks. In the present work NAA and HPGe detector γ-spectroscopy was used to determine chromium and 15 minor and trace elements qualitatively and quantitatively from chromite rock samples collected from El-Robshi area in the Eastern Desert, Egypt. The samples were properly prepared together with their standards and simultaneously irradiated by thermal neutrons at the TRIGA Mainz research reactor. Short time irradiation (1–5 min) was used to determine Mg, Ti and Mn. Long time irradiation (6 h) was used to determine Na, Ga, As, La, Sc, Cr, Fe, Co, Zn, Zr, Ce, Ce, Yb, Lu, Hf and Ta. In El-Robshi chromite comprises 18 sites, more than 100 lenses of massive chromite, more than 2700 tons averaging 44% Cr₂O₃ and the average of ⁵¹Cr 40.2%.     

Study of natural radioactivity and the state of radioactive disequilibrium in U-series for rock samples, North Eastern Desert, Egypt.

Twenty rock samples collected from North Eastern Desert in Egypt have been investigated. Natural radionuclide contents have been measured by gamma-ray spectrometry employing a shielded HPGe detector. The activities of (238)U, (232)Th and (40)K have been determined in Bq/kg dry weight. The absorbed dose rate of gamma radiation ranged from 100.48 to 22,140.53 nGy/h. The representative external hazard index values (H(ex)) for the corresponding samples were estimated. In the present work, the state of radioactive disequilibrium in the U-series at Wadi Baligh area was studied. The activity ratios between (226)Ra/(214)Pb and (214)Pb/(214)Bi were measured. The thorium-to-uranium concentration ratios (Clark value) were also estimated.     

Elemental content of feldspar from Eastern Desert,Egypt, determined by INAA and XRF

Instrumental neutron activation analysis (INAA) and HPGe detector γ-spectroscopy were used to determine a total of 16 elements qualitatively and quantitatively for the first time from feldspar rock samples collected from Gabel El Dubb, Eastern desert, Egypt. The elements determined are (Na, Mg, K, Sc, Ga, Cr, Fe, Co, Zn, Nb, Ba, Ce, Eu, Hf, Th and U). The samples were properly prepared together with their standard reference material and simultaneously irradiated by thermal neutrons at the TRIGA Mainz research reactor at a neutron flux of 7×10¹¹ n/cm² s. XRF was also used. Comparison of the results obtained by both techniques showed good agreement for such elements as K, Na, Fe, Mg, Ba and Cr.     

Epithermal neutron activation,radiometric, correlation and principal component analysis applied to the distribution of major and trace elements in some igneous and metamorphic rocks from Romania

Six major (Na, Al, K, Ca, Ti, Fe) and 28 trace (Sc, Cr, V, Mn, Co, Zn, Cu, As, Br, Sr, Rb, Zr, Mo, Sn, Sb, Ba, Cs, La, Ce, Nd, Eu, Sm, Tb, Hf, Ta, W, Th and U) elements were determined by epithermal neutron activation analysis (ENAA) in nine Meridional Carpathian and Macin Mountains samples of igneous and metamorphic rocks. Correlation and principal factor analysis were used to interpret data while natural radionuclides radiometry shows a good correlation with ENAA results.     

Evaluation of airborne gamma-ray spectrometric data for the Missikat uranium deposit, Eastern Desert, Egypt.

The examination of gamma-ray spectrometric data of the Missikat area was found to be useful in locating areas worth exploring for uranium occurrence. The statistical treatment of these data shows that the uranium threshold level is 13 ppm. Such a value represents indirectly the presence of uranium mineralization and identifies anomalous areas on the eU contour map in the northern border of the Missikat-Ria El Gerra granitic plutons. This area should be of prime concern in uranium exploration of these plutons. The interpretation of the variation in the eU/eTh ratio with eU and eTh suggests that uranium redistribution has occurred within the Missikat-Ria El Gerra granitic plutons. Uranium may be reconcentrated in silicification, sericitization and kaolinization alterations which are geologically evident. eU, eTh and their ratio eU/eTh for the Missikat-Ria El Gerra granites exhibit a lognormal distribution which is in agreement with the general distribution of trace elements, whereas the K content tends towards a normal distribution.     

Uranium-series disequilibrium dating of secondary uranium ore from the south Eastern Desert of Egypt

The secondary uranium ore of Um Ara mining area, south Eastern Desert of Egypt, is composed mainly of uranophane and β-uranophane. They occur in the oxidized zone as idiomorphic crystals filling cavities and as coatings on the fracture surfaces of the alkali-feldspar and albitized granites. The activity ratios ²³⁴U/²³⁸U and ²³⁰Th/²³⁴U of the secondary uranium ore and host rocks indicate that there were two main phases of uranium mobility in recent geological time. An earlier precipitation of uranium from solutions forming the secondary ore and a subsequent mobilization resulted in adsorption of uranium to the host granitic rocks. The ²³⁰Th/²³⁴U age of secondary uranium ore varies from (50±10) to (159+69/−45) ka whereas, the age of uranium adsorption to the rocks ranges from (18±6) to (38±5) ka. The time of secondary uranium ore precipitation can be attributed to the Saharan II pluvial period which prevailed in Egypt during humid oxygen isotope climatic stage 5. The later uranium mobility and subsequent adsorption by the rocks took place during Kubbaniyan and Nabtian pluvial periods that coincided with oxygen isotope stages 3 and 1, respectively.     

Estimation of heat generation by radioactive decay of some phosphate rocks in Egypt

Radiogenic heat production data for phosphate rocks outcropping on the three main areas Eastern Desert, Western Desert and Nile Valley are presented. They were derived from uranium, thorium and potassium concentration measurements of gamma radiation originating from the decay of ²¹⁴Bi (²³⁸U series), ²⁰⁸Tl (²³²Th series) and the primary decay of ⁴⁰K. A low radioactive heat production rate (0.32±0.1 μW m⁻³) was found for Wadi Hegaza, whereas the highest value (19±4.1 μW m⁻³) was found for Gabel Anz, Eastern Desert of Egypt.     

Uranium mineralization in the two mica granite of Gabal Ribdab area, South Eastern Desert, Egypt

Among the different rock units in the Gabal Ribdab area, the two-mica leucogranite and muscovite pegmatitic granite are the most favourable host rocks for uranium and thorium mineralization. The muscovite pegmatitic granite shows evidence of post-magmatic alteration, e.g. Na- and K-metasomatism, whereas the two-mica leucogranite could be regarded as being fresh. The spectrometric survey revealed the presence of three enriched zones with a maximum eU content of 140 ppm and the maximum eTh is 36 ppm. Uranophane, zippeite and becquerelite are the most abundant uranium minerals. The origin of these secondary minerals is mainly related to alteration of primary minerals by the action of oxidizing fluids, mobilization of uranium and then redeposition in other forms. Redistribution by circulating meteoric waters might have taken place.     

Estimation of radiation hazard indices from sedimentary rocks in Upper Egypt.

The radiological effects from 103 samples of sedimentary rocks from Upper Egypt were estimated. The mean values of radium equivalent and representative level indices in G. Sarai area are 315.3 Bq/kg and 2.2 while in G. Anz area are 299.4 Bq/kg and 2.1, respectively. The average absorbed dose rate are 136 and 141.4 nGy/h for G. Anz and G. Sarai, respectively. These average values give rise to a mean effective dose 166.8 and 173.5 microSv/y which are just about 16.7% and 17.4% of the 1.0 mSv/y recommended by the International Commission on Radiological Protection (Radiation Protection: 1990 Recommendations of the International Commission on Radiological Protection, Pergamon Press, Oxford, 1990) as the maximum annual dose to members of the public. The results indicate no radiological anomaly. The data presented here will serve as a baseline survey for primordial radionuclide concentrations in rocks of the areas.     

3D slicing of radiogenic heat production in Bahariya Formation,Tut oil field,North-Western Desert,Egypt

A 3D block of radiogenic heat production was constructed from the subsurface total gamma ray logs of Bahariya Formation, Western Desert, Egypt. The studied rocks possess a range of radiogenic heat production varying from 0.21 μWm⁻³ to 2.2 μWm⁻³. Sandstone rocks of Bahariya Formation have higher radiogenic heat production than the average for crustal sedimentary rocks. The high values of density log of Bahariya Formation indicate the presence of iron oxides which contribute the uranium radioactive ores that increase the radiogenic heat production of these rocks. The average radiogenic heat production produced from the study area is calculated as 6.3 kW.The histogram and cumulative frequency analyses illustrate that the range from 0.8 to 1.2 μWm⁻³ is about 45.3% of radiogenic heat production values. The 3D slicing of the reservoir shows that the southeastern and northeastern parts of the study area have higher radiogenic heat production than other parts.     

Radioelement distributions in the Proterozoic granites and associated pegmatites of Gabal El Fereyid area, Southeastern Desert, Egypt.

Lithologically, the rock types in the Gabal El Fereyid area are dominantly granites with minor amounts of pegmatites. The granites range in composition from tonalite to granite-adamallite with minor acidic dikes, quartz and pegmatite veins. The granite-adamallite is peraluminous and formed as a result of partial melting of amphibole-bearing rocks at depths of approximately 24-30 km and at temperatures of 800-950 degrees C. Among the different rock types, the muscovite-rich pegmatites had the highest U and Th contents (66 and 38 ppm on average, respectively). The high level of radioactivity in pegmatites is attributed to the presence of the radioactive minerals thorianite, uranophane and allanite as confirmed by XRD analysis. Binary relations of Zr/U, Zr/Th, Ce/U and Ce/Th against either U or Th in the granite-adamellite exhibit significant negative correlations indicating that both elements are not preferentially hosted in the accessory minerals phases such as zircon and monazite, but could be associated with major forming minerals such as biotite, muscovite, plagioclase and quartz, or U is situated within labile sites within granite. The uranium and thorium enrichment in the pegmatites is a two-stage process. The primary stage is magmatic whereas the secondary enrichment is from hydrothermal concentration. The magmatic U and Th are indicated by the presence of thorianite and allanite, whereas evidence of hydrothermal mineralization is the alteration of rock-forming minerals such as feldspar and the formation of secondary minerals such as uranophane and pyrite.     

Rare earth elements content in geological samples from eastern desert,Egypt, determined by instrumental neutron activation analysis

Twenty representative geological samples (tonalite, granodiorite, adamellite, syenogranite, rapakivi syenogranite, alkali feldspar granite and monzogranite) were collected from G. Kattar area in Eastern Desert, Egypt, for analysis by instrumental neutron activation as a sensitive nondestructive analytical tool for the determination of 14 rare earth elements (REEs) and to find out the following: (1) what information could be obtained about the REEs and distribution patterns of REEs in geological samples under investigation, (2) to estimate the accuracy, reproducibility and detection limit of the INAA method in case of the given samples. The samples were properly prepared together with standard reference material and simultaneously irradiated in a neutron flux of 7×10¹¹ n/cm² s in the TRIGA Mainz research reactor facilities. The gamma spectra were collected by an HPGe detector and the analysis was done by means of a computerized multichannel analyzer. The choice of the nuclear reaction, irradiation and decay times, and of the proper gamma radiation in counting are presented and discussed. The results are found to be in good agreement with certified values.     

Behavior and environmental impacts of radionuclides during the hydrometallurgy of calcareous and argillaceous rocks, southwestern Sinai, Egypt

The hydrometallurgy of radionuclides means getting the radioelements from the rocks into solution by leaching, getting the radionuclides from the solution by extraction process, and then precipitation of the desired elements to obtain concentrate. The follow-up of the radionuclides during these processes is the main target of this work to identify the identity of the original samples, pregnant solutions (leachates), residuals and the concentrate. Six samples were chosen to achieve this work. The leaching process was carried out under the conditions; 20-30% acid (H(2)SO(4)) concentration, 1:3 solid/liquid ratios, 60 min stirring time at room temperature. The activity concentrations of (238)U, (235)U, (234)U, (226)Ra, (214)Pb, (214)Bi, (232)Th and (40)K were measured in the original samples, residuals and U-concentrate (Bq/kg), and leachates (Bq/?). The results indicate that, the radionuclides before (226)Ra in the (238)U decay series are more leachable (released) than those from (226)Ra to (214)Bi in the order; (234)U>(238)U=(235)U > (226)Ra>(214)Pb>(214)Bi. (232)Th and (40)K are immobile under the present conditions. The radiological hazards of natural radioactivity in the original samples, leachates, residuals and U-concentrate were calculated and compared with the internationally recommended values and were found to be much higher than the world average values.     

Natural radioactivity and radon exhalation rate of soil in southern Egypt

The level of natural radioactivity in soil of 30 mining samples collected from six locations in southern Egypt was measured. Concentrations of radionuclides in samples were determined by γ-ray spectrometer using HPGe detector with a specially designed shield. The obtained results of uranium and thorium series as well as potassium (K-40) are discussed. The present data were compared with data obtained from different areas in Egypt.

Also, a solid state nuclear track detector SSNTD (Cr-39) was used to measure the radon concentration as well as exhalation rate for these samples. The radon concentrations were found to vary from 1.54 to 5.37 Bq/kg. The exhalation rates were found to vary from 338.81 to 1426.47 Bq/m²d. The values of the radon exhalation rate are found to correspond with the uranium concentration values measured by the germanium detector in the corresponding soil samples.     

Child deaths from family violence in Dakahlia and Damiatta Governorates,Egypt

This retrospective study evaluated 41 cases of child deaths child deaths of both sexes from family violence and autopsied at Mansoura Morgue of Forensic Medicine Institute from 1996 to 2005. According to their ages, children were divided into four groups as follow: <3 years; 3–6 years; 6–9 years and 9–12 years. Some socio-demographic parameters concerning the perpetrators were investigated such as level of education of fathers, parent marital status and residence. Also, the cause of violence and the manner of deaths were recorded. Results revealed that the highest incidence of children deaths was between 3 and 6 years (39.0%) and the lowest incidence was between 9 and 12 years (4.9%). The majority of perpetrators were males (75.62%); they comprised children fathers in 60.98%, while female perpetrators represented 24.39%; they comprised the children mothers in 7.32%. Fathers who lived in rural areas represented 75.6% and 24.4% in urban areas. Regarding the level of education of fathers of decedent children, 36.6% were illiterate, 17.1% were highly educated and 46.3% were less than high school education. The marital status of those parents were as follows: separated couples (51.2%), still married couples (22.0%); fathers with multiple wives (26.8%). Blunt trauma in abusive manner was the most common form (63.4%). It was concluded that some socio-demographic parameters are considered risk factors related to intrafamilial violence and it should be considered by Family Planning Programs to estimate the magnitude of this problem in our community on a large scale, offering psychological assessment and assurance for risky perpetrators aiming to prevent such fatal child abuse crimes.     

Health service support in Operations Desert Shield and Desert Storm.

Operations Desert Shield and Desert Storm have brought into focus a number of difficulties with the medical support of U.S. Army tactical forces. These difficulties include inadequate preparation of Medical Corps officers for command, inadequate medical training of field medical unit personnel, and problems utilizing available equipment to support Operation Desert Storm tactical operations. This paper will discuss these difficulties, potential solutions for these difficulties, and some unresolved issues created by or despite these potential solutions.     

Study on the distribution of radioactive trace elements in vitamin D-overloaded rats using the multitracer technique.

The uptake and distribution of radioisotopes of beryllium, calcium, scandium, vanadium, chromium, manganese, iron, cobalt, nickel, zinc, gallium, arsenic, strontium and barium in vitamin D (VD)-overloaded rats were investigated and compared with those in control rats, using the multitracer technique. Each element revealed its characteristic distribution among various organs in control and VD-overloaded rats. For some elements, such as cobalt and chromium, the distribution patterns in them were significantly different. These results are discussed in terms of the metabolism of the elements in rats.     

Dose rate measurements from radiopharmaceuticals: implications for nuclear medicine staff and for children with radioactive parents

Following the introduction of a number of radiopharmaceuticals, we assessed the dose received by staff working in the nuclear medicine department and also by children who may be in close contact with a radioactive parent. We measured departure dose rates (microSv.h-1) at distances of 0.1, 0.5 and 1.0 m from the skin surface at the level of the thyroid, chest and bladder of patients undergoing the following nuclear medicine procedures: MUGA scans using 99Tcm-labelled red blood cells, myocardial perfusion scans using 99Tcm-labelled radiopharmaceuticals, lymphoscintigraphy using colloidal 99Tcm (Re) sulphide, bone scans using 99Tcm-labelled oxidronate, 111In-octreotide scans, 111In-labelled leukocyte studies and cardiac reinjection studies using 201Tl. The maximum dose rates at 0.1 m were those from MUGA studies (167.3 microSv.h-1) and myocardial perfusion studies (one-day protocol = 391.7 microSv.h-1, two-day protocol = 121.8 microSv.h-1). The implications of these dose rates on both technical and nursing staff are assessed. Also, the dose received by an infant in close contact with a parent following a nuclear medicine investigation was estimated.