Behavior of uranium series in groundwater of the Wajid Formation, Wadi AdDawasir, Saudi Arabia
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Behavior of uranium series in groundwater of the Wajid Formation, Wadi AdDawasir, Saudi Arabia Y. Y. Ebaid Makhlouf
&
M. M. Nasr & J. K. B. Santos & O.
Received: 24 March 2020 / Accepted: 23 July 2020 # Springer Nature Switzerland AG 2020
Abstract The inventories and the possible mechanisms behind the relative deficiency of both radium and uranium release processes within an elevated gammaanomalous rock were investigated. A field survey was performed on the highest radioactive anomalous zone that was recorded at Jabal Al Alam (20° 13′ 10.06″ N and 44° 14′ 32.13″), with the ferruginous sandstone, iron oxide band, and iron concretions (with uranium content and reaching up to1500 ppm). The chemical analyses and the laboratory’s gamma-ray spectrometric measurements demonstrated high uranium levels in the analyzed rock samples of the Wajid Sandstone (up to 1000 ppm). The borehole geophysical logs further confirmed that the radioactive anomalies are attributed to the sandstone sequence of the Wajid Formation that is often found associated with elevated concentrations of uranium. The groundwater samples taken from the wells tapping the Wajid aquifer showed uranium concentrations ranging from 0.01 to 5.5 ppb (μg/L). The average 226 Ra in groundwater samples was 0.2 Bq L−1. The majority of the 226Ra and 228Ra activities were below the lower limit of detection (LLD). The radiochemical analyses of water samples from the Wajid aquifer display low concentrations of both uranium and 226Ra, with relation to uranium content in host rocks. This
was attributed to the fact that uranium is susceptible to form iron oxide complexes, causing them to precipitate in a more stable form. Furthermore, iron oxides coat the sand grains of the Wajid Formation and accordingly might act as a foundation for re-adsorption for both uranium and radium, resulting in their relative deficiency in the surrounding water. The coating might also act as a physical barrier resulting in hindrance of the recoil nuclei due to its significant thickness (several orders of magnitude) compared with that of the average (120 nm) whole alpha-recoil track (ART). The coating layer thickness was determined via scanning electron microscopy (SEM) and was found to be up to 180 μm.
Y. Y. Ebaid (*) Physics Department, Faculty of Science, Fayoum University, Fayoum 63514, Egypt e-mail: [email protected]
M. M. Nasr Nuclear Material Authority, Cairo, Egypt
e-mail: [email protected]
Keywords Uranium . Radium . Wajid Formation . Groundwater Abbreviations mbgl Meters below ground level API American Petroleum Institute SEMScanning electron microscope with energyEDX dispersive X-ray HPGe Hyper-pure germanium detector ART Alpha-recoil track
J. K. B. Santos : O. Makhlouf Technology Experts Company, Riyadh, Saudi Arabia
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Introduction Uranium and radium exist in the groundwater as a result of the interaction of the groundwater with the uranium series bearing rocks within the aquifer. The occurrence of uranium along with its series member (radium) concent
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