Distribution and origin of iron and manganese in groundwater: case study, Balat-Teneida area, El-Dakhla Basin, Egypt
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S. I. SCJGE-1 2019
Distribution and origin of iron and manganese in groundwater: case study, Balat-Teneida area, El-Dakhla Basin, Egypt Hassan Khozyem 1 & Ali Hamdan 1 & Abdel Aziz Tantawy 1,2 & Ashraf Emam 1 & Eman Elbadry 1 Received: 14 May 2019 / Accepted: 31 July 2019 # Saudi Society for Geosciences 2019
Abstract The groundwater contamination problem comes out from the ability of water to dissolve the aquifer materials, where any change in water acidity and alkalinity has an impact on this process. Iron and manganese are very sensitive to the water redox conditions. The present work attempts to characterize distribution and occurrence of Fe and Mn in the groundwater of Dakhla Basin, Western Desert of Egypt, their relationships with the acidity and alkalinity of groundwater, and the potential effect of oxidation-reduction conditions on their mode of occurrence. High concentrations of iron (Fe2+) and manganese (Mn2+) reductively dissolved from soil minerals have been detected in groundwater. Iron and manganese concentrations, as well as alkalinity and pH of groundwater were mapped in the study area. The concentrations of both elements are extremely high in the southern part of the study area (256 and 36 ppm, respectively) due to the high acidic character of groundwater. Two forms of Fe2+ are present (carbonate and sulfides), linked mainly to the level of the water-bearing layer depth. The iron carbonate is linked to the shallow water-bearing interval, whereas in the deep bearing water interval, Fe2+ tends to be in the sulfide form with the presence of sulfur-reducing bacteria (SRB). Mn behaves similarly as Fe but precipitated more rapidly, and the anaerobic bacteria play an effective role in concentration of both Fe and Mn in the studied samples. The long aeration time can help to drawdown the high Fe and Mn contents. Keywords Dakhla . Groundwater . Iron . Manganese . Anaerobic bacteria
Introduction Iron and manganese are commonly found in groundwater with different concentrations and consequently affecting the groundwater quality. They are mostly present in the soluble reduced divalent form as iron (Fe2+) and manganese (Mn2+) ions (Sawyer and McCarty 1967). Presence of dissolved Fe2+ and/or Mn2+ in groundwater generally reflects the anaerobic conditions prevailed due to that water is likely to be devoid of oxygen and may also have a high carbon dioxide (CO2) concentration (Casey 2009). Water containing iron and manganese in solution are colorless, but when exposed to air, it becomes cloudy and turbid This article is part of the Topical Collection on Current Advances in Geological Research of Egypt * Hassan Khozyem [email protected] 1
Geology Department, Faculty of Science, Aswan University, Aswan 81528, Egypt
2
Present address: New Valley University, New Valley, Egypt
due to the oxidation of iron and manganese and form colloidal precipitates. The oxidation rates are slow; therefore, reduced forms can be observed for some time in aerated water (Sawyer and McCarty 1967). The concentrations of iron and mang
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