Eco-Toxicological Approach as a Contribution to Integrated Water Management on Okpara Dam at Kpassa in Benin: Evaluation of Contamination of Fish and Surface Water by Organochlorine Pesticides

Abstract

The paper explores the degree of pollution of organochlorine pesticides in fish and water in the dam at Kpassa on a tributary of Okpara River that is pumped by Benin National Water agency (SONEB) in supplying drinking water to supply the city of Parakou. Doing so, fourteen parameters of organochlorine are analyzed. Most of obtain organoclorine concentration in water and fish below is indicated critical values. However, DDT and endrine concentration in water is slightly above legal tolerable values. Hexachlorobenen and dieldrine concentrations are three times higher than legal limit value while aldrine is ten times higher. However, heptachlore is double concentrated in fishery while aldrine (endrine, dieldrine aldrine, lindane, hexachloro-benzene, DDT) is found in the dam fish and surface water three times concentrated than tolerated value. These levels of concentrations result from the intensification of organoclorine pesticide used in agriculture especially in cotton production. These are caused by the chemical application accumulated in soil and through the food value chain system. Therefore, it is very important to extract sediment from the reservoir by dredging in oder to renew the ecosystem of the dam. To persistently manage the basin water resources, it is imperatively important to observe a significant behaviour changed from all stakeholders.