LE ROLE DE LA VASE DANS L’ACCELERATION DE L’EUTROPHISATION DES EAUX DE BARRAGES. ETUDE EXPERIMENTALE

Abstract

The eutrophication of water of dams is the consequence of an excessive wealth of nutritive elements in particular phosphorus and the nitrogen, thus causing an anarchistic development of the algae. It results a deterioration from the quality of the water which rough which affects its uses of which in particular that of the production of drinking water. Can the presence of the mud especially have an effect in accelerating eutrophication of water dams’ when it is known that the silting is considerable in the North Africa area? To answer this interrogation, we proceeded to a series of experiments consisting with the installation of five vats of 12 liters each one filled with water of tap and into which we introduced muds of two dams of different qualities. The evolution of the physical parameters (temperature, pH, turbidity) and chemical (phosphate, total nitrogen and silicate) was surveyed during 5 months. The results show that sediments serve as a vehicle for nutrients that cause the deposition of organic matter resulting from the degradation of plant and animal species of the aquatic environment, causing a change in pH, depletion of the medium silicates, an increase of evaporation, nitrogen and phosphorus are also included in the composition of the living cell. The temperature is very important because the appearance of algae was observed at a temperature of 20 °C.