The Quaternary sediments dominating the study area are classified into two hydrogeologic units; the upper unit is the Holocene aquitard and the lower one is the Pleistocene aquifer. The changes of lithological composition and thickness of the Holocene aquitard makes the Pleistocene aquifer more vulnerable to contamination. The deepening of Abu Zaabal Quarries and removal of basaltic sheet associated with continues groundwater flow either from the Oligocene aquifer or seepage from Ismailia canal leads to the development of a water pond filled with brackish water. The water-seepage from such pond may contaminate shallow groundwater of the Pleistocene aquifer.
The objective was to evaluate the impact of local hydrogeological conditions and human activities on surface water and groundwater quality. 6 surface water and 22 groundwater samples are chemically and bacteriologically analyzed. Water level map of the Pleistocene aquifer, thickness map of the Holocene aquitard, hydrogeological cross sections and distribution maps of different contaminants in groundwater are constructed.
Results indicate that low concentration of salinity, major ions, nitrate, trace elements are noticed in a zone adjacent to Ismailia canal, this reflects the positive hydrochemical impact of water-seepage from this canal on groundwater quality. A general enrichment of these contaminants is recorded at the northern and northwestern portions of the study area (direction of groundwater flow). On the other hand, high concentrations of salinity, sodium, sulfate, chloride, nitrate, iron and manganese exceeds the permissible limits for drinking are recorded at the southwestern portion of the investigated aquifer. The probable source of these high concentrations may be a combination of contaminated brackish water-seepage from Abu Zaabal pond and infiltration of domestic, agricultural and industrial wastes. High concentrations of sulfate and chloride ions (>250 ppm) may produce objectionable taste, act as laxative on users and may accelerate the corrosion of metals used in water-supply wells. Consumption of drinking water with high sodium, nitrate, iron and manganese can cause fatal illness. The number of E. Coli bacteria, which indicates water pollution with human sewage, is high in surface water and shallow groundwater. So, the drinking water must be treated before use. |
