Concentrations of natural radioactivity and their contribution to the absorbed dose from water samples from the Western Province, Saudi Arabia

Twenty five samples of drinking water were collected from different areas of the Western province of the Kingdom of Saudi Arabia, from Tabouk north to Abha south, nineteen of wells as well as six samples of bottled and tap water locally used in Jeddah. The collected samples were analyzed for the content of the following elements, in ppm or ppb; Calcium (Ca), Magnesium (Mg), Sodium (Na), Potassium (K), Iron (Fe), Aluminum (Al), Bismuth (Bi), Cesium (Cs), Mercury (Hg), Lead (Pb) and Uranium (U) by atomic absorption spectrometer. Also gamma spectrometer based on HPGe crystal was applied to determine concentrations in Bql of the natural radio nuclides: Uranium-238_ Radium-226 and Thorium-232 series also Potassium-40 in addition to man-made Cesium-137. Results were compared with limits given by the World Health Organization (WHO) to identify samples which are acceptable to be used for drinking purposes, to that needs chemical treatment to be acceptable. The annual absorbed doses were estimated for: ≤ 1 y, 1-2 y, 2-7 y, 7-10 y and 17 y categories from U-238, Ra-226 and Ra-228 in mSv/y. The results showed that, most of the estimated annual dose from samples exceeded the annual limit of the dose allowed by WHO (0.1 mSv/y) for all radio nuclides in drinking water.