Otieno, Peter OSchramm, Karl-WernerPfister, GerdLalah, Joseph OOjwach, Stephen OVirani, Munir2015-06-032015-06-032012Bulletin of Environmental Contamination and Toxicology April 2012, Volume 88, Issue 4, pp 526-532http://link.springer.com/article/10.1007/s00128-012-0529-7http://hdl.handle.net/123456789/1268Chlorpyrifos ethyl was found to be widely distributed in water and sediment in Lake Naivasha. Higher levels were reported in sediment (11.2–30.0 ng g−1 dry weight (dw) in wet season than in dry season (4.7–17.4 ng g−1 dw). The mean concentration of chlorpyrifos ethyl in water in wet season ranged between 8.8 and 26.6 μg L−1 and decreased to between below detection limit to 14.0 μg L−1 in dry season. On average, higher concentrations of chlorpyrifos ethyl were observed in sediment than water samples. Statistical analysis revealed a significant difference in concentration between the seasons, and a significant interaction between seasons and mean concentrations at p ≤ 0.05. However, levels of diazinon and carbofuran were below the detection limit in all the samples analyzed. Notably, levels of chlorpyrifos ethyl were higher than the maximum allowable limits (0.1 μg L−1) recommended by European Union for drinking water and general water quality criterion for protection of freshwater water organisms (0.083 μg L−1).enArticle