الفهرس | Only 14 pages are availabe for public view |
Abstract Components of natural environmental such as soils, rocks, sediments, vegetation, air and water include some naturally occurring radioactive materials (NORM). These radionuclides give rise to internal and external radiation exposures both indoor and outdoor .so, the measurements of radon exhalation rates of soil and rocks are helpful to study health hazard. According to the plan of Nuclear Materials Authority, that is based on radiation survey in various regions of the Arab Republic of Egypt. It have been developing a national program for radioactive mineral exploration, especially uranium mineralization Wadi Sahu as a part of Sinai area is inhabited by Migrant Bedouins which used natural materials in building. Also, there is a quarry and manganese mine in this region that cause significant environmental and occupational radiological impacts. The study area lies between longitude 33 º 25 `00 and 33 º 22` 19 ”East and latitude 28 º 58` 54 ”5 and 28 º 58` 00 North. The aim of the present work is to determine the environmental radioactivity hazards indices and the exposure dose rate for the public and workers from collected samples of rocks and soil, using Solid State Nuclear Track Detector (SSNTDs) of CR-39 as a tool to study 222Rn emanation for 238U prospection of the subsurface of rocks and soil distributed in the area , measure the radon exhalation rate and estimation of 222Rn and radioelement measurements in well water & plants in the investigated area. The techniques used in measurements have been carried out as follows: direct gamma dose measurements using (RDS-100) gamma survey meter, radon gas concentration in subsurface soil using closed cup technique, radon exhalation rate using closed can technique, Abstract xvi radiometric measurements for soil and plants using NaI(Tl) gamma spectrometry, radon gas concentration in water using Alpha spectroscopy (SARAD GmbH RTM1688 ) and finally analysis of environmental pollutants by Atomic absorption spectrophotometer. The results obtained from this work is useful for establishing a data baseline on the radon and gamma background radiation levels in Wadi Sahu, and represent a basis to assess any further changes in the radioactivity background levels due to various geological processes or any artificial influences around the area under considerations . Also,to prepare radioelement maps for geological study and mineral resource assessment. The results showed that ; - The average results of gamma dose rate was (0.9)μSv/h which did not exceed the recommended action limit (10) μSv/h . - The average radon concentration in the four regions were higher than the permissible limit for radon in the air outside (1-100( Bq/m3 as the first region (R1) were higher than other regions (19.84) KBq/m3. - The radon exhalation rate in the first region (R1) is higher than the rest of the other regions, -The average dose rate was (164.71 n Gy /h). and that average is greater than the world dose rate(70 n Gy /h). - The Average effective dose rate was (0.21 m Sv /y) and it is less than the world effective dose rate (0.5 mSv / y). - The average value of Raeq was (482.52) and it is higher than the recommended maximum value (370 Bq / kg). -The average External Hazard was (1.3) and it is greater than the world internal hazard (unity (1)). - The average Internal Hazard was (2.33) and it is greater than the world internal hazard (unity (1)). Abstract xvii -The average level index I-gamma was (3.27) and it is less than the world level index I-gamma (6). - The average (ELCR) was (0.73 × 10-3) and it is greater than the standard (ELCR) value (0.29 × 10-3) . - The average P-factor was (0.92) and it is less than the allowable limit (1). It has been observed that, without exception the first region (R1) was higher than the permissible values in all the hazard indices. - - The average radon concentration in well water was (86.6 Bq/m3) and it is lower than the maximum contaminant level (MCL) of (11.1 k Bq m-3) for public water supplies . - The concentration of cadmium was with value of (1.51 mg/l) higher than the permissible limit of cadmium in drinking water (0.01 mg/l) that present cadmium hazards to humans. - The concentration of lead was with value of (0.28 mg/l) higher than the permissible limit for lead in drinking water (0.05 mg/l). Form present data one may conclude; 1- Radon gas concentration and radon exhalation rate in region (R1) was higher than the other regions so we advised that the soil of this region are not safe to be used in the construction and paving works and recommend further studies on this region in the coming periods. 2- Well water in Wadi Sahu is not safe for drinking or irrigation because they contain high levels of lead and cadmium concentrations that have hazard effects to humans, animals and plants. 3- The soil to plant transfer factor data obtained from this study, could be possibility used as a natural bio-indicator for radioactive contamination in cases of accidents of unplanned releases of radioactivity to the environment. |