Abstract
Levels of dissolved ammonia, nitrite, nitrate, phosphate and silicate, as well as chlorosity, dissolved oxygen and hydrogen sulfide in the water of Lake Mariut have been investigated over a year. This shallow brackish-water lake, situated south of Alexandria, suffers from intense pollution. Two different water bodies can be distinguished in Lake Mariut. One, occupying the eastern side of the lake, is affected by sewage and industrial waste disposal, as well as discharge of highly polluted water from Qalaa Drain. The water in this region, which had lower regional average chlorosity values, contained abnormal higher concentrations of phosphate and nitrogenous salts in the presence of H2S. The western side was always oxic and showed higher average values of chlorosity. This western region contained lower concentrations of phosphate and nitrogenous salts, due to the influence of the relatively clean water from Umum Drain. The principal source of silicon for Lake Mariut is agricultural drainage. The annual average concentrations of phosphate and nitrogenous salts in this lake were considerably higher than those in the neighboring comparatively less polluted Nozha Hydrodrome. (Author 's abstract)