Evaluation of environmental radioactivity impacts and its associated radiological hazards with monitoring of radon-222 in rock and sand samples collected from some mountains and valleys in sinai area, Egypt

摘要

Determination of the natural radionuclide (~(226)Ra, ~(238)U, ~(232)Th & ~(40)K) contents of soil and rock samples collected from various geological formations in some mountains and valleys in Sinai, Egypt has been carried out using gamma spectrometric techniques. The total average concentrations of radionuclides ~(226)Ra, ~(238)U, ~(232)Th & ~(40)Kwere 51.37, 50.02, 19.34, and 286.66 Bq kg~(-1), respectively. Correlations made among these radionuclides prove there is no existence of secular equilibrium in the investigated soils. The total average absorbed dose rate in the study areas is found to be 47.08 nGy h~(-1) whereas the indoor and outdoor annual effective dose equivalent has an average value of 0.23 and 0.06 mSvy~(-1) respectively. The external and internal hazard indices and the radium equivalent activity associated with the investigated soils do not exceed the permissible limits. Moreover, the radio-elemental concentrations of uranium, thorium and potassium, evaluated for the various geological features in the study areas were calculated to indicate whether relative depletion/enrichment of radioisotopes had occurred. The results of the present study were discussed and compared with internationally recommended values. In the present study some mathematical equations models are used to estimate the activity concentrations of ~(222)Rn in the air with the activities of ~(226)Ra that contents in vegetables, as well as the doses rates that results from the vegetables consumption and from inhalation of radon gas were considered. The range of ~(226)Ra activity was found from 11.15 ± 0.96 to 135.85 ±11.68 Bq/Kg. The concentrations of radon gas in the air was determined as well as the activity concentrations of ~(222)Rn in vegetables.