Dissolved Oxygen and Organic Matter in a Harbor and a Bay in Egypt receiving Organic Pollutants from different sources

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Two shallow Mediterranean coastal basins in Egypt are subjected to different pollution levels from various land –based sources. The Eastern Harbor (EH) receives untreated domestic wastes mainly from Alexandria. Abu-Kir Bay receives highly polluted water from several industries and contaminated brackish water from Lake Edku. Distribution of dissolved oxygen (DO) and dissolved organic matter (DOM) was investigated in both basins. In the EH, photosynthetic activities and DO exchange with atmosphere controlled the surface DO budget. The high DO and low DOM at El-Boughaz opening reflect mixing of the EH waters with that of the neritic Mediterranean. The high DOM content in the EH coincided with the sewage and shipyard regimes, beside the industrial waste discharges. Contrary to the conditions in winter, the decrease in DO in summer coincided with temperature elevation. In the EH, a significant negative correlation existed between DO and DOM in the surface water, whereas it was insignificant in the bottom water. The surface annual means of DOM were higher than the middle and bottom means, reflecting direct effect of organic waste discharges. In the bay, DOM showed a noticeable decrease seaward. The high DOM at the lake-sea connection coincided with the effect of the high fertile lake water loaded with organic matter. The insignificant correlation between DO and OM and the empirical regression equations relating both variables indicate that DO was not the only factor affecting DOM decomposition.