Sediment Quality of Effluent Discharge Channels from Six Industrial Sites in Lagos, Nigeria

Concentrations of eight metals namely, Cr, Mn, Fe, Co, Ni, Cu, Zn and Pb were examined in the surface sediments of discharge channels of six industries in Lagos using x-ray fluorescence spectrometry. These channels drain into the Isolo Canal which empties into the Lagos Lagoon and eventually into the Atlantic Ocean. This study was conducted to detect any contamination levels within the sedimentsand possibly determine their sources. Sediment samples were collected over a period of six months.The results provided evidence of large differences in total metal concentrations in the sediment samples from the six industrial sites. Box plots of the average absolute deviation from median emphasized that metal concentrations were not homogeneously distributed similarly, calculation of the F ratio confirmed location effect on the concentration of the various metals investigated. The trace metals Cr, Mn, Co, Ni and Cu might be entirely from crustal materials or natural weathering processes whilea significant amount of Zn and Pb are from anthropogenic sources.