Water and Sediments Contamination by Pesticides in Sassandra River at Guessabo Area (Central-Western of Ivory Coast)

Background and Objective: Agriculture is very often practiced in rural areas and uses pesticides to improve yields. The aquatic environment is thus regularly exposed to pesticides from agricultural activity. This study aimed to assess the contamination of water and sediments of the Sassandra River by pesticides in the Guessabo area. Materials and Methods: Water and sediment samples were taken from Guessabo Lake during the rainy season at ten stations. These samples were analyzed for some pesticide actives ingredients as well as the physicochemical parameters of water. Results: The temperature and pH of the water are almost constant. The average values of temperature, dissolved oxygen, pH, conductivity and transparency were 26.82°C, 4.97 mg L‾¹, 6.82, 93.84 µS cm‾¹ and 0.95 m, respectively. It was found that the water and sediments are contaminated by pesticides. The results showed that the mean values in water were 0.0052, 0.0055, 0.635, 0.0129 and 0.0109 µg L‾¹ for Imidacloprid, Deltamethrin, Lambda-Cyhalothrin, Cypermethrin and Acetamiprid, respectively. These pesticides were found at higher concentrations in sediments than in water. The mean values in sediment were 0.01910, 0.1139, 3.8543, 0.0044 and 1.0626 mg kg‾¹ for Imidacloprid, Deltamethrin, Lambda-cyhalothrin, Cypermethrin and Acetamiprid, respectively. Lambda-Cyhalothrin was also found to be the most dominant substance in water and sediment. Conclusion: The Sassandra River was therefore mainly contaminated by pyrethroids. This presence of pyrethroids was due to the important agricultural activities that take place along the river. The organisms of this aquatic ecosystem are then exposed to the toxicity of these compounds.