The impact of three industrial effluents on submerged aquatic plants in the River Nile, Egypt

The submerged vegetation growing in the drainage channels taking effluent from three factories (two processing sugar cane plus one producing chipboard or paper pulp; and one large fertilizer plant) into the River Nile in Upper Egypt, and in the river itself upstream and downstream of the discharge points, was studied during 1994. The main pollutants from the sugar cane factory effluents comprised organic matter, including carbohydrates; from the fertilizer plant ammonia was the principal pollutant. The study investigated the effect of these different pollutants on aquatic plant standing crop and distribution, in relation to physico-chemical characteristics of water and hydrosoil. In the effluent channels, dominated by large growths of sewage fungus, submerged vegetation was absent, although some emergent vegetation survived. In the most polluted river sites, up to 2 km downstream of discharge points, the flora was restricted to Potamogeton pectinatus L. Elsewhere in the river, a more diverse submerged flora was present, including Ceratophyllum demersum L. and Potamogeton crispus L.