Radioactivity measurements and radiation dose assessments in soil of Al-Qassim region, Saudi Arabia

Abstract

The activity concentration and the gamma absorbed dose rates of the terrestrial naturally occurring radionuclides ( 226 Ra, 232 Th and 40 K) have been determined in soil samples collected from seven different locations of Qassim region in Saudi Arabia. These were performed using a NaI(Tl) gamma-ray spectrometer. The typical concentrations of 226 Ra, 232 Th and 40 K were found in surface soil samples ranged from 1.4 Bq/kg (Al Asyah) to 35.3 Bq/kg (Al Badaea), from 2.5 Bq/kg (Al Maznib) to 39 Bq/kg (Al Badaea) and from 212 Bq/kg (Al Maznib) to 915 Bq/kg (Al Badaea) Bqkg -1 , respectively. The mean radium equivalent (Ra eq ) and outdoor radiation hazard index (H ex ) for the area under study were determined as 68.1 Bq/kg and 0.18, respectively. The total absorbed dose rate due to three primordial radionuclides lies in the range 18.6-55.5 nGyh -1 with a mean of 35.2 nGyh -1 , which yields total annual effective dose of 0.37 mSvy -1 . Excess lifetime cancer risk was calculated as 0.2010 -3 . When life expectancy was taken as 70 years, the lifetime outdoor gamma radiation was calculated as 3.02 mSv which yielded a mean lifetime cancer risk of 0.0910 -3 which is below the world average (0.2910 -3 ). The measured values are comparable with other global radioactivity measurements and found to be safe for public and environment. The baseline data of this type will almost certainly be of importance in making estimations of population exposure.