Application of pollution indices in estimating the toxicity of heavy metals in sediments of Okoro River in Eastern Obolo, Southeastern Nigeria

The sediments of Okoro River were studied to assess the contamination status of the heavy metals present. Particle induced X-ray emission (PIXE) technique employed revealed the present of Ti, Cr, Mn, Fe, Cu, Zn, Rb, Sr, Zr, and Pb. The results revealed that the concentrations ranged from 1942.2-6299.3 mg/kg for Ti, 55.5 - 171.7 mg/kg for Cr, 71.7 to 374.2 mg/kg for Mn, 6881.5 - 66477.0 mg/kg for Fe, 5.9 - 37.6 mg/kg for Cu, 8.6 - 84.5 mg/kg for Zn, 0.0 - 226.4 mg/kg for Rb, 0.0 - 107.0 mg/kg for Sr, 59.7 - 1333.2 for Zr and 0.0 -51.7 mg/kg for Pb. Pollution indices such as enrichment factor (EF), geoaccumulation index (Igeo), contamination factor (CF) and pollution load index (PLI) were employed to assess the levels of pollution of the sediments of the River. The results revealed that the sediments were polluted with the present of these heavy metals detected as confirmed from the mean value of PLI greater than 1 (i.e. mean value of PLI = 1.13). This pollution is as a result of external influences on the River. The concentrations were also subjected to multivariate statistical analysis such as Pearson correlation coefficient and cluster analysis, which revealed only positive coefficient of some heavy metals and that, signified artificial similar sources of the heavy metals to the aquatic bodies in the river.