Physico-chemical parameters and levels of polycyclic aromatic hydrocarbons in water, sediments and soil in River Nzoia, Kakamega county-Kenya

The River Nzoia basin is the main source of water for domestic, agricultural, and industrial activities. The levels of the priority polycyclic aromatic hydrocarbons (PAHs) in water, soil, and sediments of River Nzoia during two seasons are reported. The physico-chemical parameters gave levels that were within the maximum allowable limit but with significant differences between the wet and dry seasons (p < 0.005). In water (max: 0.092 +/- 0.003 ng/L) and soils (max 9.74 +/- 1.97 ng/g), levels were significantly higher in the wet season unlike in sediment (8.94 +/- 3.33 ng/g). Although all levels were below the recommended limits, the results form a need basis for continuous monitoring as recommended by WHO and USEPA.