The Contamination Levels of Water and Sediment from Lake Togo by the Persistent Organic Pollutants (Pops)

This study was carried out to evaluate the contamination severity of Lake Togo by organochlorinated pesticides historically used in agriculture and in health programs against disease vectors in public health. A total of 48 samples of sediments and 48 samples of water were seasonally collected. For both sediment and water 3 samples per site were collected at 8 sites in the 2014 rainy season and in the 2015 dry season. Water samples were processed using a liquid-liquid method solvent extraction while Soxhlet extraction was used for sediment samples. The sediment and water extractions were cleaned-up and qualitative-quantitative analysis performed on gas chromatograph equipped with electron capture detector (GC-ECD). Pesticides residue levels in water ranged from < 0.001 to 0.093±0.20 µg l-1 (lindane) in rainy season and from < 0.001 to 0.352±0.07 µg l-1 (dieldrin) in dry season. They were lower than that found in sediment which ranged from < 0.001 to 0.98±0.18 µg kg-1 dry weight (pp′-DDE) in rainy season and from < 0.001 to 2.19±0.31 µg kg-1 dry weight (heptachlor epoxide) in dry season. The concentrations of the organochlorinated residues in water and sediment were higher during the dry season. Except pp′-DDE, pp′-DDD, heptachlor and heptachlor epoxide, the others pesticide residues concentrations detected in water samples in dry season were above the maximum acceptable concentration of 0.1 µg l-1 for individual pesticides set by the European Union (EU) for the protection of human health. Pesticide contamination level of Lake Togo is therefore, likely to be harmful to human health in dry season.