CONTRIBUTION TO THE STUDY OF THE POLLUTION OF NIGER RIVER WATERS: EVALUATION OF PHOSPHORUS, NITROGEN AND DISSOLVED OXYGEN CONCENTRATIONS

This work is a contribution to the study of the pollution of the Niger River and aims to evaluate the quality of its waters in phosphorus, nitrogen and dissolved oxygen. For that, eight sampling points (Gawèye, Old Bridge, New Bridge, Saga Rice Field, and Niamey National Hospital) were selected. The results obtained show that the phosphorus concentration varies from trace (Gaweye) to 0.143 mg/L (New Bridge 1); The ammonia nitrogen concentration varies from 1.5 mg / L for Gaweye 2 to 2 mg / L for the new bridge 2 and the Saga rice paddy; For dissolved oxygen, it ranges from 3.1 mg / L for the Niamey National Hospital 2 to 8.5 mg / L for the old bridge. The pollution due to phosphorus is moderate at new bridge site and absent at the others sites studied ; that due nitrogen is important at all the eight sites studied, where the pollution due to dissolved oxygen is net at new bridge, absent at old bridge and moderate at the others sites studied.