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| Assessmentof Haevy Metal Concentrationsin Waterand Sediments Of evbuarhue Riverin Ikpoba Okha Local Government Area Of Edo State,Nigeria. |
Amodu O. A., Imaji M and Ichado A.S.P
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Abstract:
This research work investigated the presence of heavy metal contamination in water and sediment of Evbuarhue River following the activities of agricultural and other minor industrial practices in the area. In this study, water and sediment samples were collected at three selected locations designated A, B and C. Two samples each were taken from each location at depths of 0 - 15cm and 15 - 30cm with the aids of pre-cleaned sterilized 1litre plastic bottle for water and a plastic hand towel for the sediment, and a GPS for geographic locations. The concentrations of 9 selected test parameters of Cu, Cr, Fe, Mg, Mn, Ni, Zn, Pb and Cd were determined by Aqua regia digestion and AAS method. The mean values and standard deviations of the various test parameters per location were obtained as follows; for water samples (Cu = 0.336±0.043, Cr = 0.030±0.009, Fe = 0.947±0.253, Mg = 0.570±0.119, Mn =0.082±0.019, Ni = 0.055±0.015, Zn = 0.471±0.082, Pb = 0.022±0.006 and Cd = 0.000±0.000) and for the sediment sample (Cu = 5.692±1.880, Cr = 1.706±0.750, Fe = 12.213± 0.658, Mg= 5.055±1.572, Mn = 3.605±0.778, Ni = 1.629±0.469, Zn=4.885±0.529, Pb=0.418±0.146 and Cd=0.080±0.015). The Mean values and standard deviation of temperature (27.7±0.230C) and pH (7.6±0.12) were within the of WHO/USEPA/EU guideline value for drinking water. The mean concentration values for heavy metals (Fe, Mn and Ni) were found to be a little above the WHO/FEPA limits while that of Cu, Mg, Zn and Cr, were little below the WHO/FEPA limits, Pb falls within the standard limit and Cd was not detected in the water sample but in sediment. However, the mean concentrations of Cu, Mg, Zn and Cr did not in any way indicate serious contamination treats since they were still below the WHO/FEPA limits for water consumption. The mean concentration values for the various test parameters in sediment samples were said to be above the WHO/FEPA guideline limits. The study revealed high concentrations of heavy metals in the sediment samples as compared to the water samples, because sediments are the major depository of metals. The findings are very useful as base line data especially for planners on water usage in the area. Activities of agricultural and industrial practices should be minimized or reduced drastically to avoid polluting the soil in the area.
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