Natural Radionuclides Concentration In Arid Environment: A Case Study

Soil salinity is a widespread environmental problem, particularly in arid and semi-arid regions of the world. Surface soil samples were collected from 14 locations arid environment at the central region of Saudi Arabia. Two samples from each location, one from cultivated land and the second from uncultivated land, of the same origin were collected from each location. This study aims to investigate the different properties of the soil in dry lands and also the concentration and distribution of its naturally occurring radionuclides. The specific activities (in Bq/kg) of 226Ra (238U series), 228Ra (232Th series) and 40 K were measured using calibrated gamma ray spectrometer. The soil physical and chemical properties [pH, EC, particle size distribution (clay, silt and sand percentages), CaCO3 %, soluble cations (Ca, Mg, Na and K) and soluble anions (CO3 , HCO3 , Cl and SO4)] were determined. The radium equivalent activity (in Bq/kg) and absorbed dose rate, one meter above the ground in nGy/y, were calculated. Due to the sandy nature of the soil and the effects of adsorption-filtration processes on the behavior and the distribution pattern of natural radioactivity concentrations in arid environment, there was no noticeable change in soil properties due to agricultural activities or strong correlations between soil properties and specific activities. Therefore, the environmental impacts of different man-made activities on underground resources should be carefully considered due to the possible filtration behavior of different pollutants in dry land environment.