An insight into ecotoxicological significance of PAHs contamination in selected Kenyan estuaries

Sediments samples from 8 selected locations along Kenyan major estuaries were analysed for PAH concentrations by gas chromatography-mass spectrophotometer. The total PAH concentrations in the sampled sites were found to be relatively low with a mean of 4.44 ng g1. Tana estuary had the highest levels of total PAHs (mean 7.22 ng g-1), while the reference location (Ramisi) had the lowest concentration (mean 0.33 ng g-1). Sediments grain size, organic matter and total organic carbon had no significant effect on PAH concentrations. All the stations were dominated by LMW PAHs apart from Tana 3 and 4 that also had substantial amount of HMW PAHs. The Fl/Fl+Pyr ratio showed that PAHs in 7 of the studied locations were primarily derived from petroleum sources except Sabaki bridge station that also had petroleum combustion sources. The levels of both individual and total PAHs in all the sampling sites were found to be significantly lower than the Effects Range Low and as such no significant ecological threats are expected.