Sediment quality assessment of rivers Abesan and Owo in parts of Lagos, Nigeria

Abstract

The present study assessed the sediment quality of Rivers Abesan and Owo in parts of Lagos, Nigeria. Data employed for this study was obtained from twenty locations. The sediment samples were analyzed for ten heavy metals [Arsenic (As), Cadmium (Cd), Chromium (Cr), Copper (Cu), Iron (Fe), Lead (Pb), Manganese (Mn), Mercury (Hg), Nickel (Ni), and Zinc (Zn)], using atomic absorption spectrophotometer. Descriptive and correlation statistics and indices were employed for data analysis. The results showed low contamination factors for Mn, Fe, Cr, Zn, Cd, As, and Ni. About 75% and 20% of the locations indicated very high and moderate contamination factors for Pb and Cu, respectively. The contamination factor for Hg showed very high contamination in all the sites. However, the pollution load index (PLI) revealed no pollution in all the areas. The geo-accumulation index (I-geo) for Mn, Fe, Cr, Zn, Cu, Cd, As, and Ni signified no contamination, while the I-geo index for Hg indicated that 35% of each site was heavily and extremely contaminated. Moreover, the I-geo for Pb provided evidence that 75% and 25% of the locations exhibited moderate to heavy contamination and moderate contamination, respectively. Also, the potential contamination index (PCI) for Mn, Fe, Cr, Zn, Cd, As, and Ni represented low contamination, while that of Cu and Hg/Pb indicated moderate and very severe contamination, respectively. The enrichment factor (EF) of Fe, Zn, and Cd indicated minor enrichment, while Cr and Cu showed moderate and moderately severe enrichment, respectively. In addition, Hg and Pb showed extremely severe enrichment. We observed a relationship between PLI and heavy metals in the study area. The heavy metals: Mn, Fe, Cd, and As have a significant impact on the sediment quality in the study area. The study recommended the monitoring of point source pollutants in the rivers catchment for sustainable environmental management.