Heavy metal concentrations in Bottom Sediments of Ikpoba River, Edo State, Nigeria

The concentrations of Fe, Mn, Zn, Cu, Pb, Cr, Ni and V were investigated. Samples were collected fortnightly from five (5) stations for four months (July to September, 2009) using Ekman grab operated by hand in shallow water. Station 1 is upstream (Old capitol bridge) and stations 2, 3, 4 and 5 are downstream. The main concentrations (ppm) in stations 1, 2, 3, 4 and 5 are: 931, 117, 812, 679 and 619.7 (Fe); 12.11, 21.08, 9.58, 8.64 and 7.89 (Mn); 9.90, 12.5, 9.64, 7.07 and 6.62 (Zn); 7.88, 8.04, 5.81, 4.34 and 3.88 (Cu); 0.48, 0.61, 0.36, 0.26, and 0.28 (Pb); 0.19, 0.26, 0.13, 0.12 and 0.11 (Cr); 0.12, 0.16, 0.08, 0.08 and 0.08 (Cd); 0.13, 0.19, 0.13, 0.11 and 0.11 (Ni) and 0.10, 0.15, 0.10, 0.09 and 0.09 (V). Analysis of variance (ANOVA) showed that Fe (Stations 1 and 2), Cr (Stations 1 and 2) and Cd (Station 2) were significantly different (p<0.05) between stations. All parameters studied were below FEPA limits. The heavy metal concentrations in bottom sediments of Ikpoba River showed a seasonal pattern of variation. This investigation in comparison with earlier study based on data from Jimoh, 2006; show that Fe and Mn concentration increased overtime while Cd, Pb, and Cu did not.