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El-Taher A.,Al Azher University | Madkour H.A.,National Institute of Oceanography and Fisheries of Egypt
Applied Radiation and Isotopes | Year: 2011

Forty-four marine sediment samples were collected in-front of wadis mouth along the Egyptian Red Sea coast: Wadi El-Hamra, Wadi El-Esh, Wadi Abu-Shaar, Wadi El-Gemal and Wadi Khashir (Hamata). Several investigations of natural activity and trace metals of surface sediments were carried out. Distributions of naturally occurring radioactive materials (NORM) of 226Ra, 232Th and 40K in the marine sediments were determined using NaI (Tl) γ-ray spectrometry. The average activities (range) of natural radionuclides in all wadis in the studied areas are 27.38 (18-48)Bqkg-1 for 226Ra, 38.45 (34-110)Bqkg-1 for 232Th and 419.4 (214-641)Bqkg-1 for 40K. These results are in agreement with earlier reported data. A comparison of radionuclide activities in the sediment of the studied areas and in other coastal and aquatic environments is given. The radiation hazard parameters (absorbed dose rate, radium equivalent activity and external hazard index) are calculated and compared with the reported data. The results of measurements will serve as base line data and background reference level for Egyptian coastlines. © 2010 Elsevier Ltd.

El-Taher A.,Al Azher University
Applied Radiation and Isotopes | Year: 2010

Uranium isotopes found in soil, rock, water, plants, air, etc., contribute to the natural radiation exposure of the population. U concentrations in some Egyptian environmental samples like Toshki soil, Aswan iron-ore, and phosphate samples from El-Sibayia in the Nile Valley and El-Quseir in the Red Sea coast were determined using instrumental neutron activation analysis (INAA) and delayed neutron activation analysis (DNAA) in the Mainz TRIGA research reactor. The results showed that the phosphate rocks are rich natural sources of uranium among the other minerals forming the earth crust. © 2010 Elsevier Ltd.

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 7×10 11n/cm 2s 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. © 2010 Elsevier Ltd.

El-Taher A.,Al Azher University | El-Taher A.,Qassium University
Applied Radiation and Isotopes | Year: 2010

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 (1-5min) was used to determine Mg, Ti and Mn. Long time irradiation (6h) 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% Cr 2O 3 and the average of 51Cr 40.2%. © 2010 Elsevier Ltd.

El-Taher A.,Qassium University | El-Taher A.,Al Azher University | Althoyaib S.S.,Qassium University
Applied Radiation and Isotopes | Year: 2012

The present work deals with identifying and determining the activity levels of natural occuring radionuclides, 226Ra and 232Th series, their decay products and 40K, in chemical and organic fertilizers used in Kingdom of Saudi Arabia. A total of 30 samples: 20 phosphatic fertilizers (single super-phosphate SSP and triple super-phosphate,TSP) and 10 organic fertilizers (cow, sheep and chicken) collected from markets and farms. The gamma-ray spectrometer consists of NaI(Tl) detector and its electronic circuit was used for measuring γ-ray spectra. The ranges of radioactivity levels of 226Ra, 232Th and 40K in chemical fertilizers are 51.5±5.2-106.3±7.5, 5.1±1.6-9.9±3.2. and 462.6±21-607.3±14Bqkg -1, respectively. The activities of 226Ra, 232Th and 40K in natural fertilizers (cow, sheep and chicken) are lower than the activities in chemical fertilizers. The obtained data are compared with available reported data from other countries in literature. The Ra eq in chemical fertilizer ranges from 100.37 to 161.43Bqkg -1 and in organic fertilizer ranges from 34.07 to 102.19Bqkg -1, which are lower than the limit of 370Bqkg -1 adopted from NEA-OECD (1979). The average heavy metal (Pb, Cd, Ni, Co and Cr) contents of the fertilizers marketed in the Kingdom of Saudi Arabia are also determined and within the limits of those used worldwide. © 2011 Elsevier Ltd.

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