Determination of natural radioactivity in irrigation water of drilled wells in northwestern Saudi Arabia

The levels of natural radiation in bedrock groundwater extracted from drilled wells in selected farms in the northwestern part of Saudi Arabia were addressed. The investigated waters form a source of irrigation for vegetables, agricultural crops, wheat, and alfalfa to feed livestock consumed by the general public Information about water radioactivity in this area is not available yet. Therefore, this study strives to contribute to the quality assessment of the groundwater of these wells that are drilled into the non-renewable Saq sandstone aquifer. Hence, gross alpha and beta activities as well as the concentrations of Ra-224, Ra-226, Ra-228, U-234, U-238, and U-total were measured, compared to national and international limits and contrasted with data quoted from the literature. Correlations between the activities of the analyzed radionuclides were discussed. The concentrations of gross alpha and beta activities as well as Ra-228 were identified by liquid scintillation counting whereas alpha spectrometry was used to determine Ra-224, (22)6Ra, U-234 and U-238 after separation from the matrix by extraction chromatography. The mean activity concentrations of gross alpha and beta were 3.15 +/- 0.26 Bq L-1 and 5.39 +/- 0.44 Bq L-1, respectively. Radium isotopes (Ra-228 and Ra-226) showed mean concentrations of 3.16 +/- 0.17 Bq L-1 and 1.12 +/- 0.07 Bq L-1, respectively, whereas lower levels of uranium isotopes (U-234 and U-238) were obtained. (C) 2015 Elsevier Ltd. All rights reserved.