MODELING OF THE LIMESTONE AQUIFER USING ...isotopes, major and trace elements. D and 18O...

Fourteenth International Water Technology Conference, IWTC14 2010 Cairo, Egypt

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MODELING OF THE LIMESTONE AQUIFER USING ISOTOPES, MAJOR, AND TRACE ELEMENTS IN THE WESTERN RIVER

NILE BETWEEN BENI SUEF AND EL MINIA

Mohamed El Kashouty

Geology Department, Faculty of Science, Cairo University, Cairo, Egypt E-mail: [email protected]

ABSTRACT A robust classification scheme for partitioning groundwater chemistry into homogeneous groups was an important tool for the characterization of Eocene limestone aquifer. The aquifer locally composed of chalky limestone with thin clay intercalated (Samalut Fm.), the fissures, the joints, and the fractures represent the conduits of the aquifer system. The flow patterns are conditioned by karstification processes which develop a conduit network and preserve low permeability microfractured blocks. The aquifer is mainly recharge by surrounding aquifers and agricultural wastewaters. The groundwater flows in the eastern part (due the Bahr Yossef and River Nile), which is a discharge areas rather than a recharge. Twenty-eight groundwater samples were collected from the Eocene aquifer and analyzed for isotopes, major and trace elements. �D and �18O concentrations ranged widely due to geology, infiltration of different surface waters, evaporation, and hydrogeology. The concentration of �D and �18O isotopes depleted due the northern zone of the northern part and western zone of the central and southern part of the study area. They enriched due the eastern area of the central and southern part of the study area. �D vs. �18O delineate the Pleistocene aquifer has a strong influence than other waters on aquifer hydrogeochemistry, confirmed by the AquaChem outputs of the mixing proportions of different water types included in the aquifer system. Cl-�D and Cl-�18O relationships indicate the role of evaporation especially due the eastern area of the central and southern part of the study area. It test the performance of the many available graphical and statistical methodologies used to classify water samples. R-mode clustering, correlation analysis, and principal component analysis were investigated. All the methods were discussed and compared as to their ability to cluster, ease of use, and ease of interpretation. Nearly most low salinity water is in equilibrium to supersaturated with respect to both carbonate minerals, while it is shift to undersaturated with salinity. The inverse modeling findings clarify that the calcite, gypsum, and anhydrite dissolution increased due the northeastern area, middle zone, and southern corner of the northern, central, and southern part of the study area, respectively. The latter areas also were characterized by the lowest precipitation of the dolomite. Such areas are distinguished by much more enhancement for aquifer permeability and therefore transmissivity. The latter areas can be used as injection zone by fresh water. It can be a triple function, firstly recharge the saline Eocene limestone aquifer through the most enhancement hydraulic conductivity and dilute it. Secondly, it enhances much more the aquifer permeability and therefore the


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transmissivity. The Eocene limestone aquifer can be improved in quality and quantity by using such model and exploit as alternative water resource with Quaternary aquifer and Nile water. Thirdly, it irrigates more areas to increase the income/capita. The dedolomitization represent the main hydrogeochemical process in the aquifer system. The geomedia (limestone, clay, marl, shale, and sand deposits) in contact to water, therefore the rock/water interaction, mixing, and ion exchange were estimated by the geochemical evolution of the groundwater systems. Keywords: Eocene limestone aquifer, Statistical analyses, PHREEQC, Geochemical

evolution of the aquifer, Isotopic compositions 1. INTRODUCTION The chemical composition of groundwater controlled by different factors such as the precipitation, the aquifer lithology, the climate, the topography, and the land use application especially agricultural and industrial activities. The groundwater samples from the area of study (Fig. 1) could potentially represent a variety of water types providing an opportunity to test the performance of many of the available graphical, hydrogeochemical, hydrogeological, and statistical techniques. The use of the major ions as natural tracers (Back [1]) has become a very common method to delineate flow paths in aquifers, besides the toxic and the isotopic elements. Generally, the approach is to divide the samples into hydrochemical facies that is groups of samples with similar chemical characteristics that can then be correlated with location.

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Fig. 1 Location map of the study area and the Clusters identified by HCA


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The spatial variability observed in the composition of the natural tracers can provide insight into aquifer heterogeneity and connectivity as well as the physical and chemical processes controlling water chemistry. Several commonly used graphical methods and multivariate statistical techniques are available including Q-mode, R-mode hierarchical cluster analysis (HCA) Judd [2]; Rummel [3]; Berry [4]; Guler et al. [5]; Johnson and Wichern [6]; and Principal component analysis (PCA). To facilitate the interpretation of the factor analysis (loadings), the factor axis was rotated by the normalized varimax method, i.e. the extracted factors were rotated in such a way that the variance of the factor loadings tend to a maximum (Davis [7]). Based on the factor loadings, each factor can be interpreted as a specific or multiple hydrogeochemical processes Usunoff and Guzman [8]; Alyamani et al. [9]; Melloul [10]. Inverse modeling attempts to determine sets of mole transfers of phases that accounted for changes in water chemistry between one or a mixture of initial water compositions and a final water composition. AquaChem (PHREEQC) program is able to include uncertainties in the analytical data that are used in the calculation of inverse modeling. This capability produces more robust inverse models that are less susceptible to large differences in results due to small changes in input data. Inverse model is currently used to assess the geochemical reactions prevailing within aquifer Parkhurst [11]; Vaute et al. [12]; Mireck et al. [13]; Stigter et al. [14]; Breukelen et al. [15]; ELRefaei [16], Abdallah et al. [17], and El Alfy [18]. The majority of PHREEQC simulation capabilities deal with so called forward modeling, you must start a given initial solution(s), which is assumed to be less chemically evolved, add some reactions such as exchanges, mineral solution, etc., and it calculates the chemistry of the initial solution after the reaction processes. The differences in compositions are assumed to be due to reactions between the water, the minerals, and the gases in contact. The object of the inverse modeling is to find sets of minerals and gases that when reacted in appropriate amounts, quantitatively account for the differences in composition between the solutions. If you want to quantify the processes along a flow line you must have a water analysis from the recharge area and from the discharge area. On the other hand, if you want to model the processes that transformed initial water(s) to current groundwater, the Nile water and Pleistocene aquifer samples are considered the initial samples in the investigated Eocene limestone aquifer. Mole transfers of phases in reaction calculations are relative to the phase, not relative to solution; positive values mean an increase in the phase; negative values mean a decrease in the phase. The model results indicate the rate of dissolution or precipitation of selected minerals in the pore spaces of the aquifer system, therefore it affects greatly on the aquifer hydraulic conductivity and therefore the transmissivity, either positively or negatively. 2. THE HYDROGEOLOGY Geomorphologically, the study area is moderately elevated plateau with respect to River Nile and composed of mainly limestone covered with alluvial deposits of sands


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and gravels (Fig. 2). The Eocene rocks constitute the main outcrops, capped by poorly consolidated sand, gravel, and clay (Quaternary aquifer). The Pleistocene sediments is the main aquifer in the Delta and Nile valley, it composed of massive cross bedded fluvial sand with gravel and clay sediments. The overlapping between the Pleistocene and the Eocene sediments at the eastern and western borders of the River Nile was established. According to geological and geophysical data, five layers were identified (Fig. 3) from top to bottom as follows (Abu Heleika and Niesner [20]): a) Unconsolidated sands and gravels (Quaternary aquifer) intercalated with clay lenses. The thickness increases generally eastwards in the direction of Nile Valley. It is partially saturated with groundwater; b) disconnected clay bands (Pliocene), completely absent in the western and northern parts of the study area (Abu Heleika and Niesner [20]). It deposited during the transgression of the Pliocene sea into the old eroded valleys of the Eocene limestone plateau (Said [21]); c) chalky limestone (Samalut Fm.) represents the investigated aquifer. It contains fissures, fractures, and joints, which all construct the conduits of the groundwater system. Total porosity 9-34 % (Fitzer et al. [22]). It detected by the Abu Heleika and Niesner [20] that the Tertiary volcanic basalts sheets intruded into the chalky limestone aquifer that enhance the interconnection of the, fissures, joint and fracture systems. There is a thin clay patches in the aquifer due the northern part of the study area.

Fig. 2 Geologic map of the study area (Conoco Coral Egypt [19] and Abu Heleika and Niesner [20]


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Fig. 3 The geoelectric cross sections a-a', b-b', and c-c' (directions approximately shown in Fig. 4) (modified after Abu Heleika and Niesner [20])

The saturated thickness of the aquifer varies from 10 to 120 m, that increased eastwards, when it becomes deeper and provides a high groundwater yield; d) limestone with shale and marl intercalation (wadi Rayan Fm.) overlying the aquifer and concentrated in the northern part of the study area. The calculated thickness increases in the northern part; e) massive limestone of El Minia and Drunka Formations underlying the aquifer system. The aquifer is mainly recharge by surrounding aquifers through fissures, joints, and fractures systems. The groundwater flows towards the eastern part (due the Bahr Yossef and River Nile) (Fig. 4). The latter is considered as a discharge areas rather than a recharge. The Quaternary and limestone aquifers are hydraulically interconnected and the former is also interconnected with the River Nile (Maxey [23]). Local karstification enhances the infiltration of the return flow (agricultural wastewater) into the aquifer system. The pumping rate ranging from 80 to 120 m3/h.


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The infiltrating water from the fields is expected to raise the water table levels, reflected by the groundwater flow towards the River Nile. In carbonate massifs, flow patterns are conditioned by karstification processes which develop a conduit network and preserve low permeability microfractured blocks (Baena et al. [24]). These processes increase the bulk permeability of the massif, developing a conduit network of high hydraulic conductivity, with short water residence time, and preserving microfractured blocks with long water-residence time. Thus, karstification provokes flow heterogeneity, increasing the permeability contrast between conduit flow and diffuse flow systems. The degree of karstification influences the flow-path length (Baena et al. [24]). However, the special character of karst aquifers such as rapid infiltration and transport over long distances makes them more vulnerable to contamination than other hydrogeological environments (Ravbar and Goldscheider [25]). Therefore, karst groundwater requires appropriate and careful managing. Generally, groundwater flows towards the River Nile in Quaternary and limestone aquifers, in eastern (Tantawy et al. [26]) and western part of the River Nile. The latter was a discharge area not a recharge, so the negative impact of the groundwater system in both aquifers will influence on River Nile water quality. Therefore, the River Nile discharge to the down gradient (due north) will affect the surface and groundwater quality, especially in the River Nile recharge areas to groundwater.

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3. MATERIALS AND METHODS Twenty-eight groundwater samples were collected from the Eocene aquifer in the western River Nile, Beni Suef-El Minia area, at about 15 to 85-m depth from the wells. Samples and water analyses were completed during the winter season (2008). The groundwater samples were taken by means of well pumps after a pumping period of at least 1 hr. The location site is determined by GPS instrument. Pre-rinsed polypropylene bottles were filled with the samples, sealed tightly. pH, electrical conductivity, and temperature are measured in situ using portable field kite. Cl, HCO3, Ca, and Mg were measured by titration, while SO4 is estimated by turbidity, and Na and K were analyzed by flame photometer. The samples were acidified with ultra pure nitric acid after filtration to avoid complexation and adsorption. The acidification was accomplished in situ and in case of toxic metals determination. Then the samples transported to laboratory and then stored in a refrigerator at approximately – 20 °C to prevent change in volume due to evaporation The toxic metals were determined by the ICP (Inductive Couples Plasma)-AES (Optima 3000; Perkin Elmer). The analyses were carried out at Environmental monitoring in Embaba, Egypt. The results of laboratory and field measurements were within 10% and therefore a significant alteration of the alkalinity during storage and transport can be excluded. The D and 18O were measured by mass spectrometer (delta-S, Theomoqt) at Berlin University, and the results of both isotopes were expressed in per mil unit as �-notation relative to Vienna Standard Mean Ocean Water (VSMOW) standard, as shown in this equation;

� = (Rsample/Rstandard – 1) * 1000 (1) Rsample and Rstandard were the measured isotopic ratio for sample and for standard, respectively. The precision for �18O and �D were 0.1 and 1 %, respectively. 4. RESULTS AND DISCUSSION

4.1. Isotopic Compositions (�2H (D) and �18O) Different isotopes of the same elements differ slightly in chemical, and more significantly in physical properties because of their mass differences. These mass difference are more pronounced in light elements, therefore, isotopes of light elements are commonly used to characterize the origin and cycle of different materials in environmental systems. The nuclear stability and the relative abundance of isotopes of oxygen and hydrogen have been widely documented. Among these isotopes, �18O, �

16O, �1H, �2H (D), and �3H are routinely used in hydrological, climatological, and geological studies. Oxygen and hydrogen isotopes are important in environmental studies because they are constituents of water and because they are conservative at near-surface temperatures. They are used together to characterize the present and past processes in which water is a dynamic component and determine the water sources. Their relative abundance in nature is highly variable. Isotopes of light elements


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undergo significant portioning (enrichment or depletion) during the course of many mass dependent chemical and physical processes. The most important elements are hydrogen, oxygen, carbon, nitrogen, and sulfur (Jager and Hunziker [27]). Oxygen and hydrogen isotopes are useful natural tracers in fluid and solid phases that affect the mineral industry effluent. The major minerals (in solid phases) affecting the oxygen isotopic signature are carbonates (investigated aquifer). Carbonate demonstrate a wide range of isotopic values, depending on the genetic (e.g. biogenic or mineralogenic) and paleo-environment of their formation. Negative �18O values (as low as -12 %) have been reported in many carbonates (Soussi and M'Rabet [28]; Kruger and Simo [29]). Other investigators have reported considerably more enriched carbonates with �18O values of 13-22 % (Fouyillac et al. [30]). Oxygen isotopic values of some igneous and sedimentary rocks have been compiled by Taylor [31]. Because the isotopic value of atmospheric oxygen (�18O = +14 %) is significantly different from that of water, oxidation processes and oxygen transport can be characterized (e.g. Richi [32]; Taylor et al. [33]). The isotopic fractionation in pyrite oxidation under laboratory conditions suggest a + �18O shift in the water (Taylor et al. [33]). In field applications, the oxygen shift is expected to be influenced further by the presence of carbonates and silicates. The magnitude of shift would be directly related to the oxidation rate and the residence time and indirectly to the permeability (Ghomshei and Allen [34). The rock/water interaction is expected to have the same �D value as the original meteoric waters. This is because rocks commonly lack significant amounts of hydrogen. Furthermore, oxidation processes are not expected to affect significantly the hydrogen isotopes in water (however, hydrogen fractionation should be quantified by experimental and field study). Therefore, groundwater is expected to show only an oxygen shift relative to the original meteoric waters (Taylor et al. [33]). The isotopic values of the groundwater samples carry two types of information; signature of the original waters and signature of oxidation with respect to carbonates or silicates overall the chemical process. The isotopic values for each water type or rock can be defined by a geochemical vector that describes the water in terms of its isotopic composition. In case of �D and �18O isotopes, this vector is defined in a two dimensional space (plotting �D vs. �18O). Mixing effects can be mathematically simulated by the addition of two vector components. In contrast, water/rock interaction can be simulated by scalar product of two vectors compositions. If one defines the isotopes vector compositions, surface waters, precipitation, groundwater, and rocks. The result groundwater is sum of all components. The isotopes in the soil profile in arid zones have been investigated differently by several authors to study infiltration and recharge (Dincer et al. [35]; Suckow et al. [36]), groundwater discharge (Christmann and Sonntag [37]), evaporation in the unsaturated zone (Allison [38]) and pollutant transport (Liu et al. [39]). Allison [38] showed that the slope of the �D and �18O regression line will be in the range between 2 and 5 in unsaturated sand compared to 5 obtained for evaporation from surface water (Osman and Abdalla [40]). The concentration of �D and �18O depleted due the northern zone of the northern part of the study area (Fig. 5). The Pliocene clay was completely absent in the northern part, cause much more leakage from the overlying Pleistocene aquifer or directly from the return flow through karst, fissures, and joint networks. The isotopic concentrations


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enriched due the eastern area of the central and southern part of the study area (Fig. 5), may partially derived from Bahr Yossef (mainly from River Nile). There is a hydraulic connection between the Bahr Yossef and the Eocene limestone aquifer, in the central and southern part. The clay thickness increased due the eastern area in the central and southern part of the study area. Therefore, the contribution from the Pleistocene aquifer and direct wastewaters leakage is more in the northern and western part of the study area, where the clay thickness is very low. The isotopic contents diluted (depleted) when the clay thickness decline (due northern and western part), while they enriched where the clay thickness increase (due eastern area of the central and southern part). The isotopic composition of the Eocene limestone aquifer is heterogeneous where delta values has a wide ranges (-7.59 to +5.01 for �18O and -58.7 to +16.3 for �D). This reflects mixing between different water types for instance Bahr Yossef, Nile water, Pleistocene aquifer, irrigation wastewaters and surrounding saline aquifers. The wide range shows the groundwater was subjected to more variable evaporation and isotopic fractionation especially the eastern zone of the middle and southern part of the study area. Strong evaporation caused isotopic enrichment in last areas (water depth < 20 m). Heavier isotopic contents suggest the groundwater has a facts local water cycle process (Fadong et al. [41]). Their concentrations deviated from the Global Meteoric Water Line (GWML) in a direction indicative of fractionation due to possible evaporation (low water depth). The isotopic contents depleted in the northern and western part of the study area, due to low evaporation rate (higher water depth 20-85 m), infiltration of different wastewaters, geology, and the rock/water interaction.

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Fig. 5 Areal distribution of �D and �18O

contents in Eocene limestone aquifer Fig. 6 The �D vs. �18O relationship (a) and Mixing

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Mixing among Pleistocene aquifer, irrigation water, and river Nile postulated by �D vs. �18O relationship (Fig. 6a). It reveals that the Pleistocene aquifer has a strong influence than other waters. Such relationship (Fig. 6a) and groundwater flow (Fig. 4) reflect the groundwater is recharged by a lateral flow from Nile water, irrigation wastewater, Quaternary aquifer, and surrounding aquifers, as well as, vertical infiltration. The overexploitation of groundwater cause recharge into the aquifer from the deeper and surrounding aquifers and wastewaters. AquaChem allows you to determine the optimal mixing ratio of the River Nile and Pleistocene aquifer, matches a target groundwater sample from the database (Fig. 6b). The contribution from the Pleistocene aquifer into the Eocene limestone aquifer was the most effective and confirms the �D vs. �18O relationship (Fig. 6a). The degree of mixing is controlled by geology, water table fluctuation among the surface and different aquifers, karstification, fissures, joints, and fractures network. The Global Meteoric Water Line (GMWL) was defined by Craig [42] as the locus of the isotope composition of worldwide freshwater sources.

�D = 8 �18O + 10 (2) This relationship commonly varies somewhat from one area to the next, given variations in climatic systems worldwide. The slope was 8 and intercept d-value was 10 for GMWL. In the Eocene aquifer (Fig. 6a), �D = 7.7 �18O + 0.8, the slope of 7.7 higher than 5 reflect mixing between different water types and local evaporation. Cl ion (conservative) vs. �18O (Fig. 7a) reflect that the data shows a wide range of isotopic signature and differ more or less greatly in Cl content. The dissolution of geomedia (limestone, marl, shale, clay and sands), water types mixing, and evaporation, contributed to current isotopic signature. Transpiration does not influence the isotopic composition of water, while evaporation highly modifies this composition and causes isotopic enrichment (Victoria et al. [43]). In addition, evaporation increases Cl concentration in the groundwater system. The areas of increasing Cl concentration in the maps mark potential discharge zones. Increasing Cl is observed in the flow terminals located southeastern, eastern, and northeastern part of the study area. The Cl concentration increases with the flow direction and reaches its peak at the hydrologic closure which confirms the significance of evaporation due the eastern and southeastern part. Like increasing Cl content, isotopic fractionation in the discharge area is attributed to evaporation (low water depth, eastern and southeastern zones of the middle and southern part of the study area). While decreasing Cl content associated with depleted isotopic composition in the recharge areas (western and northwestern part, higher water depth) is attributed to recharge from Quaternary aquifer (low salinity) and wastewaters (low aquitard thickness). The plot of �D against the concentration of Cl (Fig. 7b) will demonstrate the role of evaporation process in the eastern zone of the middle and the southern part (low water depth) (Osman and Abdalla [40]). After precipitation, water percolates into the soil, is returned to the atmosphere by evapotranspiration, or stays on the surface to join the continental water in the form of runoff. Continental water is isotopically enriched, in general, due to evaporation. The degree of this evaporative enrichment depends on temperature and relative humidity (Yehdegho et al. [44]). Evaporating waters progressively evolve


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away from the GMWL to produce lower regression slope as the evaporation process has a kinetic nature (Williams [45]). The strong correlation (R2 = 0.7) suggests that �D and �18O are not independent. Because dedolomitization and calcite dissolution seem to be the dominant geochemical reactions along the entire flow system, dissolution of carbonate minerals was regarded as an important process in determining the isotopic composition of aquifer system. The TDS-�18O (Fig. 7c) and TDS-�D relationships (Fig. 7d) indicate the mixing between the different water types with varying salinity. Such water types were plotted as references.

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Fig. 7 Cl vs. �18O (a), Cl-�D (b), TDS-�18O (c), and TDS-�D (d) of

the Eocene limestone aquifer 4.2. Multivariate Statistical Analyses 4.2.1. Correlation Analysis Total dissolved solids (TDS) is weakly correlated with CO3, HCO3, As, Cr (R2 = 0.5-0.6), and strongly correlated with Ca, Mg, Na, K, SO4, Cl, Ni, and Se (R2 = 0.6-1). It is caused partially by anthropogenic (agriculture and sanitary wastewaters) and partially by lithogenic (dissolution of geomedia, marl, shale, clay, limestone, and sand deposits) for the former. The dissolution of the geomedia contributed mainly to the latter correlation. Therefore, Ni and Se may derived mainly from the lithogenic source, whereas As and Cr may mainly attributed to anthropogenic source. The role of the agricultural wastewaters is stronger in weak correlation than those in strong. The Ca is weakly correlated with HCO3 and Ni (R2 = 0.5-0.6), and strongly correlated with Mg, Na, K, CO3, SO4, Cl, Cr, and Se (R2 = 0.6-1). It produced by the dissolution of geomedia especially limestone, shale, marl, clay, and sand deposits. Ca is strongly correlated with Mg, indicating common mineralogical sources, by the weathering of amounts of calcite Stauffer and Wittchen [46]. Cr concentration also is contributed


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partially by lithogenic source. Mg is weakly correlated with Cr and HCO3 (R2 = 0.5-

0.6), and strongly correlated with Na, K, CO3, SO4, Cl, Ni, and Se (R2 = 0.6-1). K is weakly correlated with As and Cr (R2 = 0.5-0.06) and strongly correlated with SO4, Cl, Ni, and Se (R2 = 0.6-1). HCO3 is weakly correlated with SO4, Cl, and Cu (R2 = 0.5-0.06) and strongly correlated with Cr and Ni (R2 = 0.6-0.8). The HCO3 was partially caused by lithogenic and anthropogenic sources, these metals in last correlation were produced by mixing, rock/water interaction, and dilution processes. The Cu concentration in groundwater is mainly caused by anthropogenic source. SO4 is weakly correlated with As and Cr (R2 = 0.5-0.6), and strongly correlated with Cl, Ni, and Se (R2 = 0.6-1). The role of return flow was very clear in the last weak correlation than those in the strong. Cl is weakly correlated with As, and Cr (R2 = 0.5-0.6) and strongly correlated with Ni and Se (R2 = 0.6-0.9). As and Cr reflect their anthropogenic influences than lithogenic. Pb is correlated with Cd caused by fertilizers especially phosphate and super phosphate fertilizers commonly used. Ni is correlated with Cr, Sn, Hg, Ag, and Se (R2 = 0.6-0.8). Such last correlation delineates the same characters of these metals in the aquifer system. These metals caused partially by lithogenic and partially by anthropogenic sources. The correlation analysis identified that As and Cu are mainly anthropogenic especially fertilizers and pesticides, while Se is mainly lithogenic, whereas Ni, HCO3, Cr, SO4, and Cl contents in groundwater system partially derived from anthropogenic (agricultural activity) and partially from lithogenic sources. pH is inversely correlated with major ions may be evidence of the increasing importance of adsorption processes. 4.2.2. Cluster Analysts Another approach to understanding the chemistry of water samples is to investigate relationship among the dissolved constituents and environmental parameters such as lithology, using dendrogram analysis (Drever [47]). Hierarchical Cluster Analysis (HCA) classifies the data in a relatively simple and direct manner, with the results being presents as a dendrogram, an easily understood and familiar diagram. The resulting graph (Fig. 8) was interpreted to have classified the water samples into six clusters (A-F) and one independent case, based on physical properties, major ions, toxic elements, and water table of the aquifer system. This however is a subjective evaluation. Figure 9 shows the mean concentrations of dissolved elements in groundwater of the clusters produced by the HCA.


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Dendrogram using Average Linkage (Between Groups) Rescaled Distance Cluster Combine C A S E 0 5 10 15 20 25 Label Num +---------+---------+---------+---------+---------+ Case 2 2 -+ Case 4 4 -+-----+ Cluster A Case 1 1 -+ +---+ Case 19 17 -------+ +-----------+ Case 17 15 ---+---+ I I Case 20 18 ---+ +---+ I Case 5 5 -----+-+ +-----+ Case 16 14 -----+ I I Case 3 3 -----+-+ Cluster B I I Case 10 10 -----+ +---+ I I Case 11 11 -------+ +-----------+ I Case 9 9 ---------+-+ I Case 14 12 ---------+ +---------+ Case 15 13 -----------------------------+ I Case 6 6 -----------+---------------+ I +---------+ Case 8 8 -----------+ Cluster C +-+ I I Case 7 7 ---------------------------+ I I Case 18 16 -------------Independent case----------+ I Case 27 25 ---------+-----------------+ I Case 28 26 ---------+ Cluster D I I Case 23 21 -----+-------+ +---------------------+ Case 24 22 -----+ +-------+ I Cluster E Case 21 19 -------------+ +-----+ Case 25 23 ---------+-------+ I Case 26 24 ---------+ +---+ Case 22 20 -----------------+ Cluster F

Fig. 8 Q-mode dendrogram of major and toxic elements

of the Eocene limestone aquifer

Fig. 9 Average major and toxic elements concentrations of clusters identified by HCA

Cluster A include 7 samples (1, 2, 4, 5, 17, 19, and 20), located due the southwestern and northwestern part (i.e. near the beginning of the groundwater flow path, Fig. 4). It


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is characterized by the lowest average concentrations of SO4 and HCO3 caused by low dissolution rate of geomedia and much recharge from the overlying Quaternary aquifer (low salinity). These samples located where Pliocene clay thickness completely absent due the northern part (samples 17, 19, and 20) and decreased in thickness in the western zone of the middle and the southern part of the study area (samples 1, 2, 4, and 5). As a result this cluster identify the lowest concentrations of Pb, Zn, Ni, As, Cd, Cr, Sn, Hg, and Al, attributed to low dissolution and high recharge from the overlying Quaternary aquifer (low salinity). Cluster B include 6 samples (3, 9, 10, 11, 14, and 16), located scattered allover the study area. They are in the northern part (sample 16), middle part (samples 9, 10, 11, 11, and 14), and in the southern part (sample 3). It is difficult to explain it, because it is distinguished by different geology, dissolution rate, and wastewaters dumping. Cluster C composed of 4 samples (6, 7, 8, and 15), distributed in the middle part. This cluster is characterized by the lowest average TDS concentration, caused by lowest Pliocene clay thickness, which enhance much infiltration from the overlying Quaternary aquifer (low salinity). Such cluster is distinguished by highest average concentrations of Sn, Hg, Ag, and Al. These toxic metals derived partially from anthropogenic and partially from lithogenic. These samples located where the Pliocene clay thickness decreased that permit the leakage from the agricultural wastewaters. Some toxic metal concentrations associated with low and high TDS concentrations, confirm that they are attributed to lithogenic and anthropogenic sources. Cluster D represented by samples 27 and 28; they were in the northern part of the study area (Fig. 1). The average TDS concentration was higher than the previous clusters, attributed to dissolution of geomedia (marl, shale, clay, limestone, and sand deposits); it is characterized by highest concentrations of Pb, Zn, Ni, As, Cd, Cr, Sn, and Se. This cluster is much dissolute and locates near the end of the groundwater flow path and also received agricultural wastewaters. Cluster E consists of 3 samples (21, 23, and 24), it is near the northeastern part (Fig. 1). It is distinguished by the highest concentration of TDS due to high concentration of marl, shale, limestone. Also, it represent the highest concentrations of Se and Cu. Cluster F represent 3 samples (22, 25, and 26); located in the northeastern part (Fig. 1), it is distinguished by the highest concentrations of CO3 and HCO3. Sample 18 was independent case, caused by the highest content of Cd concentration. 4.2.3. Principle Component Analysis Six factors whose Eigen values are more than 1 were initially extracted accounting for 84 % of the variance (Fig. 10). Factor 1 is grouping the positive loading of TDS, Ca, Mg, Na, K, CO3, SO4, Cl, Ni, and Se (Fig. 10). It represents the dissolution of geomedia (marl, clay, shale, limestone, and sand deposits), so it is named mineralization factor. Factor 1 is negatively loaded with pH and �2H (Fig. 10), indicate that the deuterium is not influenced by dissolution process and the geomedia concentration of hydrogen was minimum. The pH negative loading was attributed to adsorption, precipitation, and co-precipitation processes in the aquifer-aquitard systems. Factor 1 also influx of more waters from the surrounding aquifers and wastewaters infiltration. Factor 2 represented by positive loadings of Ni, As, Cr, Sn,


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Hg, and Ag, may attributed to anthropogenic and lithogenic sources. It is called toxic metal factor due to high association of these metals with it. It indicates the same behaviors of these metals from their origin, occurrence, sorption, desorption, and rock/water interaction. Factor 3 include positive loading of �2H and �18O and constitute the isotopic factor. It clarifies the different characteristics of the major and toxic elements in one side and the isotopic elements in other side with respect to hydrogeochemical trend. Factor 4 consists of Pb and Cd, because of agricultural activity especially fertilizers, which apply phosphate and super phosphate fertilizers. It is known as fertilizer factor. Factor 5 is negatively loaded with Cu and Zn, may attributed to different sources for both metals. Therefore, it is called anthropogenic factor, especially agricultural impact. Factor 6 is negatively loaded with water table; delineate the negligible impact of water table fluctuation on hydrogeochemical behaviors of the aquifer-aquitard systems. Such factor represents the water table factor. Table 1 addresses the six factors identified by rotated principle component analysis and the corresponding elements.

Table 1 Varimax rotated principle components of six factors.

Factor number

Principle component Type Loading Variance

%

Variables contributing significantly

to the principle components

F1 Mineralization Positive 0.56-0.96 38 TDS, Ca, Mg, Na, K, CO3, SO4, Cl, Ni,As, and Se Negative -0.12 pH and D

F2 Toxic metals Positive 0.56-0.81 15 Ni, Ag, Cr, Sn, Hg, and Ag F3 Isotopic contents Positive 0.71-0.82 9 D and 18O F4 Fertilizers Positive 0.8-0.81 8 Pb and Cd F5 Anthropogenic Negative -0.71 &

0.87 7 Cu and Zn

F6 Water table Negative -0.88 7 Water table The relationship among the six factors delineate that factor 3 (isotopic content) is correlated with factor 6 (water table), show the impact of water table fluctuation on isotopic compositions in the aquifer system. Factor 4 (fertilizers) is weakly correlated with factor 3, indicate the impact of wastewaters on isotopic compositions. Factor 4 is strongly correlated with Factor 5 (anthropogenic); reflect the impact of agricultural wastewaters on factor 4.


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Fig. 10 Rotated factor analysis of the major and toxic elements of the Eocene limestone aquifer

4.3. Na-Cl relationship The fundamental concept in the mixing approach is:

Measured groundwater composition = mixing + reactions (3) This leads to the need to solve the problem of mixing before the effects from reactions can be described. The main aim of the model was to differentiate in the groundwater between what is due to mixing/transport and what is due to water/rock reactions by using one variable such as Cl as a conservative tracer to create an ideal mixing model between two extreme waters. The groundwater is always a result of mixing and reactions. The aquitard diffusion model explaining the distribution of Cl- also constrains the behavior of the cations. Diffusion of only Cl- would produce a charge imbalance (Domenico and Schwartz [48]). Thus counter ions must diffuse from the aquitard to maintain electroneutrality. If the relation between Na and Cl is straight line with strong correlation, it delineates the same source (leaching), which obvious in Fig. 11. Figure 11 is clarifying hypothetical pathways of chemical evolution generated by adding equivalent amounts of Na+ and Cl- to water from the recharge area. Na values were higher than Cl values in some samples indicating that sodium is not only derived from halite dissolution, but also from surface irrigated water and rock-bearing minerals according to the following equation (Afzal et al. [49]):

Ca2+ +2Na-clay � 2Na+ + Ca-clay (4)


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Fig. 11 Na-Cl relationship of the Eocene limestone aquifer

In fact, transferred water was dominated by Ca and HCO3 with low to medium to high TDS. Na, Cl, and SO4 were the dominant ions with high TDS, which increased gradually towards the distal end of the groundwater flow path. It can be described as ion exchange play important role in Na concentration in groundwater system as follows (Appelo and Postma [53]):

1/2Ca2+ + Na-X � 1/2Ca-X2 + Na+ (5) where X indicates the soil exchanger, Ca was taken up from transferred water from surface meteoric water. As a result the transferred water evolved Ca(HCO3)2 to NaHCO3 when discharged into groundwater, which the Na was the highest cationic composition. 4.4. Saturation Index Approach Calculation of a mineral saturation index (SI) is a convenient method of representing the equilibrium condition of a solution with respect to a mineral.

Saturation index (SI) = log IAP/Kmineral (6) K is the solubility product defines as the solubility constant and calculated by the law of mass action Appello and Postma [50], SI = 0, mineral is in equilibrium with solution; SI<1, under-saturated and SI>1; over-saturated. By using the saturation index approach, it is possible to predict the reactive mineralogy of the subsurface from the groundwater data without collecting samples of the solid phase and analyzing the mineralogy. The saturation indices for calcite and dolomite generally inversely correlated with TDS (Fig. 12a). Nearly most low salinity water (< 1500 ppm TDS) is in equilibrium to supersaturated with respect to both minerals. It is attributed to carbonate minerals could be a controlling concentrations of calcium, magnesium, and


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bicarbonate in water in the aquifer system. The low salinity water is more able to dissolve the limestone sediments than high salinity. By increasing TDS (> 1500 ppm), the saturation index shift to undersaturated with respect to both minerals (Fig. 12a). In addition to the agricultural wastewater shares in the chemistry of the environment. With TDS, the saturation index of carbonate minerals increased, later on they precipitated. Gypsum saturation indices for groundwater collected as a part of this investigation (Fig. 12b) increases with increasing sulfate concentrations. Gypsum would tend to dissolve in water that is undersaturated with respect to gypsum. Sulfate concentration increases along flow path until saturation with gypsum occurs and therefore serves as a proxy for distance from the recharge area (Kehew [51]). The saturation indices of selected minerals are illustrated in Fig. 12c, the groundwater is equilibrium to supersaturated with respect to alunite and gibbsite, while the rest minerals are undersaturated. The saturation indices for calcite vs. dolomite (Fig. 12d), reflect the relatively flow system length that the major samples were closer to calcite than dolomite. Fig. 12e indicates that pH is inversely related to PCO2 for a solution in equilibrium with calcite. This relationship holds true for groundwater that do not contain excessive acids or bases (Kehew [51]). The partial pressure of the groundwater vs. SI of calcite is depicted in (Fig. 12f) to show the gradual change in PCO2 from atmospheric to the present pressures.

a d

b e

c f

Fig. 12 Saturation indices outputs of the Eocene aquifer system based on major and toxic elements


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4.5. Inverse Geochemical Calculations The PHREEQC code uses the chemical compositions of two waters (i.e., initial and final) that are assumed representative for the upstream and downstream points of the same flow line. Then, depending on the number of chemical constituents and the selected mineral phases associated with them, a number of reaction sets are proposed by the model to explain the hydrogeochemical evolution in part of the aquifer between the initial and final points. Plausible sets of reactions are determined by subjective reasoning. In all geochemical models, Ca, Mg, Na, K, Cl, SO4, CO3, HCO3, Pb, Cu, Zn, Ni, As, Cd, Cr, Sn, Hg, Ag, Al, Se, Fe, Mn, and Co were used as chemical constituents whereas the dissolving/precipitating phases included calcite, dolomite, gypsum, anhydrite, and CO2 (g) are feed the code. These phases were chosen based on available information on the aquifer mineralogy. Nile water and Pleistocene aquifer compositions have been used as initial waters for the models of selected sites through other elected wells. The mass transfer rates determined by PHREEQC indicate extensive calcite and anhydrite dissolution, remarkable gypsum precipitation and/or dissolution, and extensive dolomite and CO2 (g) precipitation (Fig. 13). The calcite has +ve value of phase mole transfer (Fig. 13a), indicate more dissolution, which increases in the northeastern area, middle zone, and southwestern corner of the northern, central, and southern part of the study area, respectively. The calcite dissolution was enhanced the aquifer permeability and therefore transmissivity, through the increase in the pore spaces of the aquifer. The increase in the permeability and transmissivity was predicted in the previous areas. Dolomite precipitation was predominant in the study area (Fig. 13b), reflected by the -ve value of phase mole transfer. It reflects the precipitation of dolomite in the pore spaces of the Eocene limestone aquifer and consequently decreases the permeability and transmissivity. The rate of precipitation decreases due the northeastern zone and middle area of the northern and central part of the study area. The gypsum was precipitated in the aquifer by the – ve values of phase mole transfer in the northwestern zone and southwestern corner of the northern and southern part of the study area, respectively (Fig. 13c). They are causing a decrease in the aquifer permeability and transmissivity in the latter areas. On the other hand, the gypsum phase mole transfer was +ve in the middle and southern part, reflect dissolution process of the gypsum. The latter areas were characterized by enhancement of the aquifer hydraulic conductivity and therefore transmissivity. The anhydrite phase mole transfer was dissolute and precipitate (Fig. 13d), delineating much more enhancement in the aquifer permeability and transmissivity either positively or negatively. The anhydrite +ve phase mole transfer was in the northeastern area, middle, and southern corner of the northern, central, and southern part of the study area, respectively. The CO2 (g) is resemble the gypsum precipitation/or dissolution processes (Fig. 13e). It can be concluded that the calcite, gypsum, and anhydrite dissolution increased due the northeastern area, middle zone, and southern corner of the northern, central, and southern part of the study area, respectively. The latter areas also were characterized by the lowest precipitation of the dolomite. Such areas are distinguished by much more enhancement for aquifer permeability and therefore transmissivity. The latter areas can be used as injection zone by fresh water. It can be a triple function, firstly recharge the saline Eocene limestone aquifer through the most enhancement hydraulic conductivity and dilute it.


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10 28

28 20

28 30

30 35 30 40

10 28

28 20

28 30

10 28

28 20

28 30

10 28

28 20

28 30

10 28

28 20

28 30

30 35 30 40 30 35 30 40 30 35 30 40 30 35 30 40

0 2

a- Calcite, mmole/kg b- Dolomite, mmole/kg c- Gypsum, mmole/kg D- Anhydrite, mmole/kg e- CO2 (g), mmole/kg

km

0.0085

0.0081

0.0067

0.0069

0.0081

-0.0001

-0.0006

-0.0025

-0.0027

-0.00290.007

0.002

Fig. 13 Phase mole transfer by dissolution and precipitation, from the initials wasters and final Eocene aquifer system

Negative sign indicates mass removed from the aqueous phase; positive sign delineate dissolution.


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Secondly, it enhances much more the aquifer permeability and therefore the transmissivity. The Eocene limestone aquifer can be improved in quality and quantity by using such model and exploit as alternative water resource with Quaternary aquifer and Nile water. Thirdly, it irrigates more areas to increase the income/capita. 4.6. Dolomitization and Dedolomitization Processes The reaction of calcite and dolomite with water and CO2 can be written as follows:

CaCO3 (calcite) + H2O + CO2 Ca2+ + 2HCO3 (7) CaMg (CO3)2 (dolomite) +2H2O + 2CO2 Ca2+ + Mg2+ +4HCO3 (8)

Typically CO2 was derived from the oxidation of organic matter and root respiration in the soil zone and was dissolved by recharge water. If dolomite dissolves according to the last equation, the molar proportions of [Ca+Mg] to [HCO3] should be linear, with a slope of 0.5 (Sandra and George [52]). Most of the samples do not follow the dolomite dissolution trend (Fig. 14a) and were correlated well with Ca, Mg, and HCO3. This lack of agreement clarifies that other processes were controlling the chemistry of the groundwater such as dedolomitization process. On a plot of [Ca+Mg] as a function of [SO4+0.5HCO3], the dedolomitization (dissolution reactions with carbonate minerals and gypsum) reaction yields a straight line with a slope of 1. There is a well agreement between the theoretical dedolomitization model and most of the samples (Fig. 14b), except a few. The latter samples are characterized by high HCO3 concentration. The groundwater was formed during the meteoric water infiltration through the soil when the water became saturated by carbon dioxide (CO2) because of the organic matter oxidation. On the flow pathway further along, the CO2 enriched groundwater dissolves calcite and becomes enriched in Ca 2+ and HCO3 ions:

CaCO3 + CO2 + H2O � Ca 2 + + 2HCO3 (9) When the value of TDS in groundwater increases, the CO2 partial pressure increases from the meteoric average level 10-3.5 to 10-2 atm (Fig. 14c). When the CO2 partial pressure increases, the groundwater geochemically becomes supersaturated with dolomite. In this case the groundwater leaches the dolomite (or high Mg–calcite), which results in the dedolomitization of the aquifer matrix and higher concentrations of Ca 2+, Mg 2+ and HCO3 ions as estimated previously by dedolomitization model.

Ca 2 ++ HCO3 + CaMg (CO3)2 + H2O � Ca 2 ++ Mg 2 ++ CaCO3 + 2HCO3 + (OH)- (10)


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a b c

Fig. 14 Dolomite dissolution, (a), dedolomitization (b), and TDS-Total CO2 content

relationship of the Eocene limestone aquifer 4.7. Geochemical Processes and Groundwater Evolution The rock/water interaction and the mixing of the Nile water with releases of sedimentation water was investigated through ion pairs relationship, where the scattered plots are best fitted with the least square to determine with more certainly the variations between the two variables (Collins [53]). The TDS vs. Mg, Na, and Ca concentrations (Fig. 15a, b, and c), clarify low cationic contents at low TDS (< 1500 ppm) and increased in concentrations with TDS (> 1500 ppm). The main source of Mg concentration in groundwater is geomedia dissolution (limestone). These relationships reflect mixing processes among different water types such as agricultural wastewaters, Pleistocene aquifer, Nile water, surrounding aquifers, and rock/water interaction. The dissolution of geomedia (clay, shale, marl, limestone, and sand deposits) produces high concentration of Mg, Ca, and HCO3 in the aquifer system. The Ca-HCO3 relationship (Fig. 15d) depicts the dissolution of the limestone sediments. The saturation index of calcite and dolomite vs. the Mg (Fig. 16a) and Ca (Fig. 16b) represent the moderate inverse relationship among them. It indicates a different sources for Ca and Mg concentrations in groundwater for instance dissolution of geomedia, return flow, and surrounding aquifers. These inverse relationships delineate dissolution of limestone to become supersaturated, then they are precipitated after saturation with TDS in groundwater system.


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a c

b d

Fig. 15 Mg, Na, Ca, and HCO3 relationships of the Eocene limestone aquifer

a

b

Fig. 16 Mg and Ca- saturation index of carbonate minerals relationships of the Eocene limestone aquifer

The chemical evolution in the study area can be explained by direct infiltration of different waters with some sequent uptake of CO2 in soil, lithogenic in the dissolution of underline limestone, marl, shale, clay and sand sediments. The hydraulic dissolution reactions of geomedia form dissolved bicarbonates, calcium, and magnesium ions, can be described as follows (Appleo and Postma [54]).

CaCO3 + H2O � Ca2+ + 2HCO3 - + OH- (11)

CO2 + H2O � HCO3- + H+ (12)

CaMg(CO3)2 + 2H2O � Ca2+ + Mg2+ + 2HCO3- + 2OH- (13)

2CO2 + 2H2O � 2HCO3- + 2H+ (14)


��

The molar Mg/Ca rations in groundwater samples were lower than 1 which suggests that dissolution of limestone is faster than magnesium. With the groundwater flow, the TDS and water type changed depending upon the geographic positions (Fig. 17). The water infiltrated through the karstic formation and at this stage attained a relatively stable chemical composition. When transferred Nile water and Pleistocene aquifer of CaHCO3 type infiltrates, it may mix with local groundwater of Eocene limestone aquifer. The chemical mixture formed was shown in Fig. 17, associated with precipitation of gypsum according the following equation (Wang [55]).

Ca2+ + 2HCO3- + 2Na+ + SO4

2- CaSO4 + 2Na+ + 2HCO3- (15)

By mapping hydrogeochemical facies in different areas, the groundwater flow patterns can be described (Fig. 19). The hydrogeochemical facies reflected the response of chemical processes occurring within the lithologic framework and also the pattern of groundwater flow (Back 1960 [56]; [57]). The stiff plotting technique (Stiff [58]) was used to describe the chemical evolution of groundwater along water flow path. The area of the diagram is an approximately indication of TDS (Hem [59]; Stiff [58]). The transformation of water types resulted mainly from the limestone dissolution and ion exchange.

1

2 3

4

5

6

78

91011

12 1314

15

1617 18

19

20212223242526

27

28

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30 35 30 40

0 2km

Na-Cl-SO4

Na-Cl-SO4Na-Ca-Mg-Cl-SO4

Na-Cl-SO4 Na-Cl-SO4

Na-Cl-SO4Na-Ca-Cl-SO4

Na-Cl-SO4

Na-Cl-SO4

Na-Ca-Cl-SO4

Na-Ca-Mg-Cl-SO4 Na-Cl-SO4

Na-Ca-Cl-SO4

Na-Ca-Mg-Cl-SO4

Na-Ca-Cl-SO4

Na-Cl-SO4

Na-Cl-SO4

Na-Ca-Cl-SO4

Na-Cl-SO4

Na-Cl-SO4

Na-Cl-SO4

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Na-Cl-SO4

Na-Cl-SO4

Na-Cl-SO4 Na-Cl-SO4 Na-Cl-SO4 Na-Cl-SO4

1 Sample numberSample site

Groundwater flow

Water sources

Fig. 17 Stiff plot of with water type below of the Eocene limestone aquifer


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5. CONCLUSIONS The isotopic contents can determine the origin of the groundwater systems and the rate of the evaporation in the Eocene limestone aquifer. The hierarchical cluster analysis (HCA) technique was judged most efficient because it offers a semi-objective graphical clustering procedure (dendrogram), which does not require pre-determining the final number of clusters. The PHREEQC model revealed the change in aquifer hydraulic parameters through the phase mole transfers estimation. The water injection in the highest dissolute area can be used as storage for water shortage periods. The hydrogeochemistry predict the evolution of the groundwater system from the surface meteoric water to rock/water interaction or mixing or ion exchange to the current state. REFERENCES [1] Back, W. Techniques for mapping of hydro chemical facies. US Geol Surv,

1966. [2] Judd, G. The use of cluster analysis in the derivation of geotechnical

classification. Bull Assoc. Eng. Geol. 17: 193-211, 1980. [3] Rummel, J. Applied factor analysis, Northwestern University Press, Evanston,

1970. [4] Berry, K. Spatial reasoning for effective GIS. GIS World Books, Fort Collins,

Colardo, 1995. [5] Guller, G., Geophrey, D., McCray, J. Evaluation of graphical and multivariate

statistical methods for classification of water chemistry data. Hydrogeology Journal, 10: 455-474. 2002.

[6] Johnson, A., Wichern, W. Applied multivariate statistical analysis. Prentice-Hall, Englewood Cliffs, NJ, 1992.

[7] Davis, J. Statistics and data analysis in geology: John Wiley and Sons, NY, Toronto-Singapore, 1986.

[8] Usunoff, E. and Guzman, A. Multivariate analysis in hydrochemistry; An example of the use of factor and correspondence analyses. Groundwater v 27, no. 1, pp. 27-34, 1989.

[9] Alyamani, M., Bazuhar, A. and Hussein, M. Interpretation of groundwater chemistry by factor analysis technique. JKAU; Earth Sci v 7, pp. 89-100, 1994.

[10] Melloul, A. Use of principle components analysis for studying deep Aquifers with scarce data-application to the Nubian sandstone aquifer, Egypt and Israel. J Hydrogeol v 3, no. 2, pp. 19-39, 1995.

[11] Parkhurst, D. User’s guide to PHREEQC A computer program for speciation, reaction path, advection transport, and inverse geochemical calculation. USGS, Water Res. Invest. Report 95-4227, 143p, 1995.

[12] Vaute, L., Drogue, L., Garrelly, L., and Ghelfenstein, M. Relations between the structure of storage and the transport of chemical compounds in karstic aquifers. J. Hydrology 199, Elsevier Science, pp. 221-238, 1997.


��

[13] Mirecki, J., Cambpell, B., Colon, K., and Petkeewich, M. Chemical changes during aquifer storage recovery testing in a limestone/clastic aquifer. Groundwater, v. 36, no. 3, pp. 394-403, 1998.

[14] Stigter, T., Ooijen, S., and Post, A. A hydro geological and hydro chemical explanation of the groundwater composition under irrigated land in a Mediterranean environment, Algarve, Portugal, J. Hydrology 208, Elsevier Science, pp. 262-279, 1998.

[15] Breukelen, B., Appelo, C., and Olsthoorn, T. Hydro geochemical transport modeling of 24 years of Rhine water infiltration in the dunes of the Amsterdam water supply. J. Hydrology 209, Elsevier Science, pp. 281-296, 1998.

[16] El Refaei, A. Geochemical modeling of groundwater in the New Minia city, Egypt. Egyptian J. of Geology, v. 46/1, pp. 317-328, 2002.

[17] Abdallah, G., Eweida, A., Dahab, K., and Farid A. Hydro chemical model for the Lower Cretaceous aquifer in Sinai peninsula, Egypt. 5th Intern. Conference on Geology of the Arab World, Cairo Univ., pp. 863-874, 2000.

[18] El Alfy, M. Geochemical characteristics and pollution assessment of the groundwater of the Quaternary aquifer, Qatia area, north Sinai, Egypt. 6th Intern. On Geochemistry, Alexandria Univ., v. 3, pp. 271-292, 2004.

[19] Conoco Coral Egypt. Geologic map of Egypt (Scale 1: 500000). General Petroleum Company, Cairo, Egypt, 1987.

[20] Abou Heleika, M., and Niesner, E. Configuration of the limestone aquifers in the central part of Egypt using electrical measurements. Hydrogeology Journal, Vol. 17, No. 2, pp. 433-446, 2009.

[21] Said, R. The geology of Egypt. A.A. Balkema/Rotterdam/ Brookfield, 734 pp, 1990.

[22] Fitzner, B., Heinrichs, K., and Labouchardiere, D. Limestone weathering of historical monuments in Cairo, Egypt. Proceedings of the 5th EC Conference “Cultural Heritage Research: a Pan-European Challenge, 16–18 May 2002, Cracow, Poland, p. 367, ICSC - Institute of Catalysis and Surface Chemistry /Polish Academy of Sciences, Cracow / Poland, European Communities, 2003.

[23] Maxey, G. In: Chow VT (Ed.) Hydrogeology, handbook of applied hydrology. Chap. 4. McGraw-Hill, New York, 1964.

[24] Baena C.; Andreo B.; Mudry J.; Carrasco F (2008). Groundwater temperature and electrical conductivity as tools to characterize flow patterns in carbonate aquifers: The Sierra de las Nieves karst aquifer, southern Spain. Hydrogeology Journal. Porf, pp. 380-382.

[25] Ravbar, N., Goldscheider, N. Comparative application of four methods of groundwater vulnerability mapping in a Slovene karst catchment. Hydrogeology Journal, 2008.

[26] Tantawy, M., El Sayed, E., Setto, I., and Abu El Seba, E. Hydrochemical evaluation of the groundwater resources in the area east of Minia district, Egypt. El Minia Science Bulletin, Fac. of Sci., El Minia University, v 17 (1) pp. 24-57, 2006.

[27] Jager, E., Hunziker, J. Oxygern and hydrogen in the hydrosphere and the atmosphere. In; Lectures in isotope geology. Springer, Berlin Heidelberg NY, pp. 343-345, 1979.


��

[28] Soussi, M. and M'Rabet, A. Burial dolomitization of organic rich and organic poor carbonates, Jurassic of central Tunisie. In: Purser B., Tucker M., Zenger D. (eds.) Dolomites. Special Publication of the Internal Association of sedimentologists, Blackwell Oxford Internal, 21: 429-445, 1994.

[29] Kruger, J. and Simo, J. Pervasive dolomitization of subtidal carbonate ramp, Silurian and Devonian, Illinois basin, USA. In; Purser B., Tucker M., Zenger D. (eds.) Dolomites. Special Publication of the Internal Association of sedimentologists, Blackwell Oxford Internal, 21: 387-405, 1994.

[30] Fouillac, A., Domanget, A., and Milsi, J. A carbon, oxygen, hydrogen, and sulfur isotopic study of the gold mineralization at Loulo, Mali. Chem Geol 106: 47-62, 1993.

[31] Taylor, H. Water/rock interactions and the origin of H2O in granitic batholiths. J Geol Soc London 133: 509-558, 1977.

[32] Richie, A. Sulfide oxidation mechanisms: controls and rates of oxygen transport. In; Jambor J., Blowes D. (Eds.) Short Course handbook on environmental geochemistry of sulfide mineral wastes. Mineral Association of Canada, Toronto, Ontario 22; 201-245, 1994.

[33] Taylor, B., Wheeler, M., and Nordstrom, D. Stable isotope geochemistry of acid mine drainage; experimental oxidation of pyrite. Geochem Cosmochem Acta 48; 2669-2678, 1984.

[34] Ghomshei, M., and Allen, D. Potential application of oxygen-18 and deuterium in mining effluent and acid rock drainage studies. Environmental Geol 39 (7) pp. 767-773, 2000.

[35] Dincer, T., AL-Mugrin, A. and Zimmermann, U. Study of the infiltration and recharge through the sand dunes in arid zones with especial reference to the stable isotopes and thermonuclear tritium. J Hydrol 23:79–109, 1974.

[36] Suckow, A., Sonntag, C., Groening, M. and Thorweihe, U. Groundwater recharge in the Umm Kedada Basin, NW-Sudan, derived from environmental isotopes of soil moisture in samples collected from deep dug wells. In: Thorweihe U., Schandelmeier H. (eds.) Geoscientific Research in Northeast Africa. Proc. of Intern. Conf. on Geosci. Res., Northeast Africa, Balkema, Rotterdam, pp. 677–685, 1993.

[37] Christmann, D. and Sonntag, C. Groundwater evaporation from East-Saharan depressions by means of deuterium and oxygen- 18 in soil moisture. In: Isotope techniques in water resources development (Proc. Ser. Symp. IAEA, Vienna). IAEA, Vienna, pp 189–204, 1987.

[38] Allison, G. The relationship between 18O and Deuterium in water sand columns undergoing evaporation. J Hydrol 55:163–169, 1982.

[39] Liu, B., Philips, F., Hoines, S., Campbell, A. and Sharma, P. Water movement in desert soil traced by hydrogen and oxygen isotopes, chloride, and chlorine-36, southern Arizona. J Hydrol 168, 91–110, 1995.

[40] Osman, A. and Abdalla, E. Groundwater recharge/discharge in semi-arid regions interpreted from isotope and chloride concentrations in north White Nile Rift, Sudan. Hydrogeology Journal, Vol. 17, No. 3, pp. 679-692, 2009.

[41] Fadong, L., Guoying, P., Changyuan, T., Qiuying, Z. and Jingjie, Y. Recharge source and hydrogeochemical evolution of shallow groundwater in a complex


��

alluvial fan system, southwest of north China Plain. Environmental Geology, Vol. 55, No. 5, pp. 1109-1122, 2008.

[42] Craig, H. Isotopic variation in meteoric waters. Science 133 (3465):1702–1703, 1961.

[43] Victoria, R., Martinelli, L., Mortatti, J. and Richey, J. Mechanisms of water recycling in the Amazon Basin: isotopic insights. Ambio 20:384–387, 1991.

[44] Yehdegho, B., Rozanski, K., Zojer H. and Stichler, W. Interaction of dredging lakes with the adjacent groundwater field: an isotope study. J Hydrol 192:247–270, 1997.

[45] Williams, A. Stable isotope tracers: natural and anthropogenic recharge, Orange County, California. J Hydrol 201:230–248, 1997.

[46] Stauffer, R. and Wittchen, B. Effects of silicate weathering on water chemistry in Forested, upland, felsic terrane of the USA: Geolchimica et Cosmochimica Acta, v. 55, p. 3253-3271, 1991.

[47] Drever, I. The geochemistry of natural waters, 3rd Edn. Prentice-Hall, Upper Saddle River, NJ, 1997.

[48] Domenico, P. and Schwartz, F. Physical and chemical hydrology. John Wiley and Sons Inc., 824p, 1987.

[49] Afzal, S., Ahmed, J., Youmas, M., Dinzahid, M., Khan, M., Ijaz, A. and Ali K. Study of water quality of Hudiara drain, India-Pakistan. Environmental Geology 26:87-96, 2000.

[50] Appelo, C. and Postma, D. Geochemistry, groundwater and pollution. A.A. Balkema, Rotterdam, Netherlands, 536p, 1993.

[51] Kehew, A. Applied chemical hydrogeology. Hall Inc., New Jersey, 368p, 2001. [52] Sandra, M. and George, L. Regional groundwater flow and geochemistry in the

Midwestern basins and Arches aquifer system in parts of Indiana, Ohio, Michigan, Illinois, 2000. US Geological Survey, Professional paper, 1423-C, 100p.

[53] Collins, A. Geochemistry of oilfield waters. Elsevier, Amsterdam, 475p. [54] Appelo, C. and Postma, D. Geochemistry, groundwater and pollution. 2nd

Edition. AA Balkema, Amsterdam, 649p, 1975, 2005. [55] Wang, D. Base of hydrogeology. Geological Press, Beijing (in Chinese), 1986. [56] Back, W. Origin of hydrochemical facies of groundwater in the Atlantic Coastal

Plain. Int. Geol Cong, 21st, Proc, pt 1, Copenhagen, pp 87-95, 1960. [57] Back, W. Hydrochemical facies and groundwater flow patterns in northern part

of Atlantic Coastal Plain. USGS professional paper 498-A, pp. 1-42, 1966. [58] Stiff, H. The interpretation of chemical water analysis by means of patterns,

J. Pet Technol 3:15-17, 1951. [59] Hem, J. Study and interpretation of the chemical characteristics of natural

water. USGS Water supply paper 2254, 1989.

MODELING OF THE LIMESTONE AQUIFER USING ...isotopes, major and trace elements. D and 18O...

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