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Abstract
El-Khadra lake was physically, chemically and microbiologically evaluated at surface layer and depths of 30 cm, 1 meter and sediment water in September 2011 and February 2012. Physico-chemical analysis of lake water samples revealed the alkaline nature of the lake with high concentrations of Na+ and Cl- ions at all depths in both seasons. Na+ ion concentrations ranged from 27.124 to 30.569 g/l in September samples and from 9.235 to 9.734 g/l in February samples, while Cl- ions ranged from 15.606 to 21.275 g/l in September samples and from 10.686 to 11.928 g/l in February samples. Higher bacterial counts were detected in sediment water samples in both seasons (990 and 910 cfu/ml in September and February samples, respectively). Fungal counts were higher in September samples at 1meter depth (290 cfu/ml), while in February samples, the higher fungal counts were recorded at 30 cm (110 cfu/ml). Total and feacal coliforms scored few numbers in both seasons. Many cyanobacterial species besides some algae were detected in the lake including Chlorella, circular diatom (Puncticulata sp.), Oscillatoria, Spirulina, Nostoc and Anabaena spp. Among those, three representative species were isolated and identified by TEM and molecular techniques as Spirulina sp., Oscillatoria sp and Anabaena sp.