Bulletin of Environmental Contamination and Toxicology 2012-04-01

Spatial distribution and temporal trend in concentration of carbofuran, diazinon and chlorpyrifos ethyl residues in sediment and water in Lake Naivasha, Kenya.

Peter O Otieno, Karl-Werner Schramm, Gerd Pfister, Joseph O Lalah, Stephen O Ojwach, Munir Virani

Index: Bull. Environ. Contam. Toxicol. 88(4) , 526-32, (2012)

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Abstract

Chlorpyrifos 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)).