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Radiological and Mineralogical Studies on some Selected Farm Soils and Phosphate Fertilizers |
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PP: 67-76 |
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doi:10.18576/jrna/100110
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Author(s) |
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Shimaa AM Amer,
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Abstract |
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| Recently, using chemical fertilizers, especially phosphates for high productivity of crops increases soil contamination by radionuclides. Soil samples were collected from three governorates (El Sharqia, El Giza, and El Fayoum), and the used fertilizers are represented by superphosphate and phosphogypsum. All these samples were analyzed radiometrically for radionuclides determination (U, Th, Ra in ppm & K in percent) and investigated mineralogically. The concentration of radionuclides in various governorates is lower than the permissible international levels, suggesting unhazardous limits. A significant concentration of radioelements was found in El Sharqia governorate on average, 1.3 ppm for uranium and 5.94 ppm relative to the others. This could be related to the presence of clay minerals montmorillonite-chlorite and kaolinite with gypsum and associated minerals such as rutile and quartz. The radioelements contents in El Giza soil, average uranium (1.03 ppm) and thorium average (4.83 ppm) may be revised to its adsorption on clay mineral kaolinite and montmorillonite. Fayoum soil samples average uranium are 0.66 ppm and thorium 4.83 ppm and characterized by the presence of clay minerals (kaolinite, Chlorite-vermiculite-montmorillonite) with zirconium silicate mineral. The activity concentrations of uranium and radium in all superphosphate samples were higher than the worldwide average, whereas the activity concentrations of thorium and K-40 in most samples were lesser. Phosphogypsum samples have uranium and thorium contents less than the superphosphate fertilizer but with higher radium and potassium contents. The notable high radium concentration in phosphogypsum could be related to its precipitation with calcium and Ba as Ra sulfates.
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