Contributions to the protection of a lentic system in the tropical region against chemical pollutions: A case study of “Toho Lake” in Southeastern Benin, West Africa

Document Type : Original Article

Authors

1 National Water Institute, Department of Hydrology and Water Ressources Management ( Laboratory of Hydrology Applied), Abomey-Calavi, Benin

2 Department of Chemistry, Faculty of Science and Technology of Natitingou (Natitingou Water and Environmental Chemistry Laboratory) BP:710 Abomey- Calavi, Benin

3 Department of chemistry, Ecole Normale supérieure de Natitingou (Natitingou Water and Environmental Chemistry Laboratory) BP:710 Abomey- Calavi, Benin

4 National University of Agriculture, Departmenent : School of Plant and Semitic Production and Management (EGPVS), BP:840 Abomey-Calavi, Benin

5 Department of Chemistry Faculty of Science and Technology of Abomey-Calavi (Calavi's Water and Environmental Chemistry Research Laboratory ); BP:710 Abomey- calavi, Benin

Abstract

The protection of aquatics ecosystems leads to the biological equilibrium which secures the safe foods from the aquatics products. Toho Lake located to the southeastern of Benin is threatened by human pollution due to the chemical fertilizers, waste housekeeper, and both human and animal excrement result agglomeration. The aim of the present study is to Toho lake protection against chemical and bacteriological pollution of these wet ecosystems. Samples of water and sediment were collected and analyzed by HACH DR 3900 after undergone treatment The different analysis results revealed mean oxygenation of water (4,95mgo2/l), the Biochemical Oxygen Demand (21.5 mgo2/l), the Chemical Oxygen Demand (149, 39 mg/l) with the azote in Nitrate (NO3:0,18mg/l), ammoniacal azote (N-NH4+:0,47mg/l) phosphorous (2,06mg/l) are very high. The lake is also polluted by fecal matters. The high contents of heavy metals in the sediment show that the sediments of the lake are polluted by the zinc (340mg/kg), the cadmium (7mg/kg), the lead (60,75mg/kg), and the copper (8,25mg/kg).

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