Water Quality and Trophic Status of a Lake (Mariut, Egypt) Eight Years After Diversion of Wastewater Effluents

Abstract

Water resource management and lake rehabilitation is a global interest, to overcome the acute water scarcity facing most urban areas, especially in developing countries. Lake Mariut (LM) is an Egyptian lake that lies south of Mediterranean Sea, and its management had a great interest in Alexandria’s future development and as a part of the environmental sustainability of the Mediterranean basin. LM consists of 4 major basins namely, main basin MB, NWB, SWB, and FB. The MB has deteriorated as it consistently received (sewage and industrial) wastewaters till 2010. This was the date of diversion of the polluting sources as a rehabilitation step. The present work is made after elapsing 8 years from the diversion and aims at monitoring and assessing the status of the water quality not only of MB but also for the other 3 basins too. This was carried out twice, one in cold winter and the other in warm summer. The parameters studied were physico-chemical ones including DO besides nutrient salts (N and P compounds). The results revealed that the waters of both MB and SW basin were depleted in DO to a level difficult to sustain fish life. Tropically, all the studied basins were in eutrophic-hypereutrophic condition. The depletion in the vital DO is catastrophic and needs urgent solution/s. One of the proposed solutions is the dredging of bottom spoiled organic-rich sediments. This and other suggested solutions are, however, discussed, evaluated, and presented.