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Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/9948

Title: Chemical Characteristics of Groundwater and Composition of The Newly Formed Precipitates in Arid Environment
Authors: S. AI-Sewailem
A. S. AI-Mashhady
A. Sh. Sallam
Issue Date: 1999
Publisher: The Third Conference on Desertification and Environmental Studies (Beyond the year 2000). King Saud Unvi.
Abstract: Chemical characteristics of groundwater and the composition of newly formed precipitates are critical in the management of modem irrigated agriculture in arid regions. Water samples representing the main aquifers in Riyadh region, Saudi Arabia, and solid samples from the newly formed precipitates were studied. Results showed that water temperature varied between 30.3 - 69°C, being higher in the deep aquifer and low in the relatively shallow aquifers. Initial water pH ranged from 6.39- 7.92, increasing to 7.65 8.20 at atmospheric conditions. Shallow aquifer waters were categorized into sulfate-type and Cl-or no-dominant type waters, while the deep aquifers were characterized as Cl-type and no-dominant type. Soluble ~Si04, Fe and Mn ranged from 3.15 to 18.82, 0.10 to 17.30, and 0.01 to 0.32 mg L'l, respectively. Calculation of saturation indices from water composition at initial, closed and equilibrium conditions indicated that changes in pH and water temperature cause major chemical changes in the water favoring the precipitation of carbonates and Fe-silicates. Data of total chemical analysis indicated that carbonates are present in all samples and constituted up to 976 g Kg'l of the precipitates formed from the deep aquifer water in the irrigation tubes. Amorphous and/or crystalline Fe compounds were the dominant fractions in the surface crust precipitates, while crystalline Fe compounds was the dominant form in the precipitates found in the irrigation tubes and in the cooling reservoir. XRD data confirmed that aragonite was the dominant carbonate mineral in the precipitates formed from the deep aquifer water. Calcite and Mg-calcite were detected in considerably low quantities. Poorly crystalline Fe-oxide minerals were present in all the precipitate samples.
URI: http://hdl.handle.net/123456789/9948
Appears in Collections:College of Foods And Agricultural Science

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