Assessment of the Hydrogeochemical Processes Affecting Groundwater Quality in the Eocene Limestone Aquifer at the Desert Fringes of El Minia Governorate, Egypt

Abstract

El Minia Governorate is within the Nile Valley and is surrounded by the Eocene limestone plateaus from the east and west. The present study focuses on the hydrogeochemistry of the Eocene limestone aquifer in both the eastern and western desert fringes of El Minia. Thirty groundwater samples from the Eocene aquifer (east and west of the Nile) and seven samples from post-Eocene aquifers in this area were analyzed to assess the groundwater geochemistry, isotopic compositions and the subsurface hydrology. Samples obtained from depths of 24-120 m were measured for major components, nutrients, oxygen-18, deuterium and carbon-13. The groundwater TDS (total dissolved solids) concentrations ranged from 530 to 2788 and 453 to 1903 mg/l at the western and eastern desert fringes, respectively. Values of Eocene aquifer water d 18 O ranged from -8.31 to -0.44 and -2.07 to 0.55 %, and those of water dD ranged from -63.6 to -2.32 and -9.03 to 5.03 % for the Eocene aquifer at the western and eastern side, respectively. Chemical analysis shows that the main chemical facies of the Eocene water are Ca-Mg-HCO 3 and Ca-SO 4 . The chemical and isotopic data show that water-rock interaction (calcite dissolution and silicate weathering) and mixing between different water types control the major ion chemistry of Eocene aquifer water. The chemical composition of Eocene water has also evolved by evaporation and ion exchange. The present study indicates the need for regional chemical and isotopic study for the Eocene aquifer along the Nile Valley region to delineate the sources of recharge to this important aquifer.

Assessment of Groundwater Quality for Different Uses Case Study: El Minya Governorate, Egypt

“…The high TDS ascribed to groundwater wells of the present study located in the Eocene fractured layers and the groundwater potential depends mainly on the secondary porosity. As well as the relatively low rate of recharge since the recharge sources to the Eocene aquifer include percolation of the modern precipitation, occasional flash floods and local seepage from the quaternary aquifer and probably upward leakage from the Nubian sandstone aquifer (Ibrahim and Lyons (2017). The high values of TDS in the control year (2011) in comparison with the monitoring years are in agreement with US EPA (2013) due to the intrusion of cement grout into the screened intervals during the construction of wells.…”

Utilizing the geological data and remote sensing applications for investigation of groundwater occurrences, West El Minia, Western Desert of Egypt

“…western part reveal a contribution from the paleo-water of the Nubian sandstone aquifer through the upward leakage. This is confirmed by the highly depleted values of stable isotope (−7.7 of δD and −5.46 of δ 1 8O & −63.6 of δD and −8.32 of δ 1 8O, Gameil and Berry Lyons, 2017) (Fig. 5a).…”

“…-The stable isotope values of the groundwater The stable isotope values are ranging between (−17.1 and 22.9 of δD, and −3.31 and 2.70 of δ 1 8O, Gameil and Berry Lyons, 2017) in the groundwater of the Middle Eocene aquifer. These values confirm that groundwater receive recharge from the Nile River where it has an isotopic signature of modern Nile water.…”

Hydrogeologic investigations to determine the sources of groundwater recharge of Samalut carbonate aquifer in some wadis, East El Minia, Egypt

“…The Cl-18 O pattern reflects dissolution of halite (Ibrahim and Lyons 2017;Figure 18). This means that Cl does not conservative.…”