الفهرس 
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Abstract
A hydrochemical and environmental study has been conducted on lake Qarun, Fayoum governorate. Lake water was sampled along horizontal and vertical profiles. The main feeding sources of lake water El-Batts and El-Wadi drains were also sampled. Major chemical composition, halogens, trace elements, isotopic content (Oxygen-18 & Deuterium and Tritium) and natural radioactivity were determined. The data were analyzed and treated through hydrochemical and isotopic modeling.
The high salt content of drainage water to lake Qarun and the effect of evaporation led to a serious increase of salinity (average TDS =33570 ppm). The variation of composition of inflow water is dampened by mixing with the major bulk of lake water which becomes homogenized and well mixed. The salt load of the lake is high enough to reach an over-saturation, and precipitation takes place for Calcite, Dolomite, Aragonite and Gypsum. The turnover time of lake Qarun water is quite low about 5 years, based on tritium modeling. This is correlatable with high evaporation intensity as being the only mechanism of removal of water from the system. Mathematical models are used to simulate water quality variations, salt balance and turnover time of lake Qarun. An evaporation factor of about 370.8 was calculated using Netpath modeling program, describing the development of present day lake water composition from a continual (along with time) inflow of drainage water composition. The precipitation of relevant phases in the system has been quantified and the time elapsed to reach the present day situation of the lake was estimated.