الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Cairo City is one of the oldest Islamic cities all over the world. The southern part of Cairo or so-called Historical Cairo contains abundant Roman, Coptic, and Islamic monuments. Most of the monuments in Historical Cairo are made up of limestone which was quarried from the Middle Eocene Mokattam Group.
Historical Cairo has been subjected to many environmental changes, which have posed a threat to the archeological buildings. The main cause of these changes is the rising of groundwater level due to the urbanization of Greater Cairo. This urbanization caused additional inputs to groundwater from various sources such as garden irrigation, sewage leakage and the development of the highlands adjacent to Historical Cairo such as the Mokattam plateau and Al Fustat Park.
Also, the high concentration of dissolved salts and change in groundwater quality affected the buildings and the underneath soil. The groundwater is mostly polluted by chemicals used in industry, urban wastes and agriculture. These environmental changes led to deterioration of the buildings and forming swamps in the low-lying areas such as the area of Fustat excavation and the vast expansions of Ain El-Sira and Khayalat Al Shorta lakes.
Cairo lies entirely in the arid subgroup or desert with hot climate. The recorded average annual relative humidity is 54.21%. This city is dominated by NNE and N wind directions with an average speed of about 11-16 knots. December, January and February are the biggest months of rainfall, which range between 1.0 and 0.1 mm.
This study aims to evaluate the geo-environmental hazards caused by the rise of the groundwater level and atmospheric conditions in Historical Cairo through the use of field and laboratory methods.
The studied sites in Historical Cairo are located between Longitudes 31˚14’0” and 31˚16’0” E, and Latitudes 29˚59’30” and 30˚1’0” N. They include Roman monuments (Babylon Fortress), Islamic monuments (Al Fustat City, Aqueduct of Ahmed Ibn Tulun and Bir Umm Al Sultan, The Mausoleum of Al Tabataba, Domes of Sabab Banat, Dome of Abu Al Qasim Al Tayeb, Imam Al Shafai Mosque, Athar Al-Nabi Mosque, Magra El-Oyoun Fence, Imam Al Layth Mosque, The tombs of the royal family and Al Jabakhana) and Ain El-Sira and Khayalat Al Shorta lakes.
Nine water samples were collected from the surface water in the study area (Khayalat Al Shorta Lake, The Mausoleum of Al Tabataba, Ain El-Sira Lake and Old Al Fustat City. The measured physicochemical and microbiological parameters of the collected water samples are pH, EC, Ca, Mg, Na, K, Cl, NO3, SO4, HCO3, Fecal and Total coliforms.
Also, twenty samples were collected from the studied heritage building stones and their weathering crusts. These samples were chemically analyzed using X-ray Fluorescence Spectrometry (XRF). Mineralogical analyses of these samples were carried out by X-Ray Diffraction (XRD) and thin sections investigations.
In addition, maps of the studied sites showing the locations of water and rock samples were prepared using the commercial GIS software ArcGIS 10.4.
The obtained pH values (7.53 - 7.77, average 7.64) revealed that the studied water samples are slightly alkaline. This fact may be result from the interaction between geologic formations and pollutants with water resources in the study area. The electric conductivity of the analyzed water samples revealed that most of these samples showed results above the maximum limit of the used portable instrument (20 mS/cm). Electric conductivity is basically related to the ionic content in water which could be acquired by some geochemical process such as reverse osmosis, ion exchange, silicate weathering, evaporation, sulphate reduction-oxidation, rock water interaction processes and human activities.
The recorded cations in the studied water samples are Na+>K+>Mg2+>Ca2+. The concentrations of these cations in the studied water samples are sometimes higher than those of the normal lake and sea water. All recorded cations show mutual significant correlation. On the other side, the recorded anions are Cl->SO42->NO3->HCO3-. The concentrations of all anions, except Cl-, in the studied water samples are lower than those of the normal lake and sea water. Also, all recorded anions show mutual significant correlation.
The plotting of studied groundwater samples on Piper (1944) diagram show that the samples are dominant in class II (Na-K-Cl-SO4 type) indicating the prevailing of alkalies (Na+K) and stronger acids anions (Cl+SO4) over the alkaline earths (Ca+Mg) and weaker acids anions (CO3+HCO3). This class indicated the prevalence of halite weathering and the infiltration of surface salts. Since the climate of Cairo is always dry and hot as well as anthropogenic inputs, dissolved Na, K, Cl and SO4 concentrations continue to accumulate in the lakes by evaporation with the dominance of Na and SO4. The dominance of Na in the groundwater samples may be attributed to silicate mineral weathering and ion-exchange processes on clay particles. The presence of alkalis cation facies represents the prevalence of human interventions, like leaching of industrial effluent and wastewater, rather than natural weathering.
The recorded high concentrations of fecal coliform bacteria can be attributed to the leakage of wastewater into the studied water lakes.
Thin sections investigation of the collected building stones samples revealed that the studied rocks are classified into bio-micrite (60%), bio-intra-micrite (15%), micrite (15%), intra-bio-micrite (5%) and dolo-intra-bio-micrite (5%).
The XRD patterns of the investigated building stone samples showed that calcite and quartz are the most predominant detected minerals. Also, some minor amounts of evaporite minerals were detected such as gypsum and halite. On the other side, weathered crust samples are dominated by halite and gypsum with minor occurrences of calcite and quartz minerals. Moreover, other evaporite minerals such as anhydrite and sylvite were detected in some samples. Traces of dolomite is recorded.
The XRD results and thin section investigation of both types of samples indicated that the building stone samples are sandy limestone which may be of similar composition to those of the Middle Eocene limestone forming some outcrops in the nearby mountains. This fact confirms that the building stone of the studied heritage sites maybe quarried from the nearby mountains