Physico-Chemical Characterization of Waters and Sediments of Basins in the Cotton Area in Benin: Case of the Alibori Basin in the Commune of Banikoara North of Benin

摘要

The Alibori Basin, with an area of 13,400 km2, is a tributary of the Niger River in Benin. It is a river that passes through the potentially agricultural area of Benin. The waters of the river are useful for wildlife and are used for various purposes (drinking water, laundry, domestic activities). They regularly receive the discharges and drainage of the residues of the chemical fertilizers and pesticides not used by crops during the cultivation of the river and watershed bank. This study aims to assess the impact of the agricultural inputs on the quality of the waters from Alibori river on the basis of its physico-chemical characteristics and concentrations in Trace Metal Elements such as Zn, Pb, Cd and Cu. Seven (7) sites were selected along the river. Concentrations of , , , ?, Cu2+ and Zn2+ were measured using a spectrophotometer DR 1800 and that of Pb and Cd by Metalyse. The Metal Trace Elements were measured in the Alibori river sediments after being treated and mineralized using aqua regia. The results revealed that Alibori river characteristics varied with seasons and its waters and sediments were polluted by metals, phosphates and nitrites. The pollution of waters of the Alibori River was due to the intensive use of the chemical fertilizers and pesticides for agricultural purposes.