Paper
Chemical Fractionation of Heavy Metals in Surface Runoff and Associated Sediments of Ile- Ife and Oshogbo Township
- Authors:
- Olabanji I.O; Ogunfowokan A.O; Adeyeye O.F
- Abstract
- This study investigated the heavy metal speciation of surface runoff and associated sediments in Osogbo and Ile-Ife to determine the contribution of heavy metals to environmental pollution in the area. Samples were collected along major roads with high traffic density within each town, and processed appropriately. The sequential extraction described by Tessier, et al. 1979 and Tokalioglu, et al. 2000 were used to respectively fractionate the sediment and water samples, which were then analysed by Atomic Absorption Spectrophotometry(AAS) to determine concentrations of four heavy metals: Pb, Mn, Ni and Cd. Results indicated that the pH values of the collected runoff samples ranged from 6.80-8.10 to 6.80-7.40 in Osogbo and Ile-Ife, respectively. The total metal concentrations in the Osogbo samples ranged from 14.48-26.03µgg-1Cd, 99.73-156.45µgg-1Mn, 24.50-52.25µgg-1Pb and 18.45-28.33µgg-1Ni while heavy metal concentrations in Ile-Ife ranged from 15.45-27.53µgg-1Cd, 70.03-153.45µgg-1Mn, 20.00-27.98µgg-1Ni and 20.28-32.75µgg-1Pb.The order of decreasing bioavailability of detected heavy metals in sediment fractions from Osogbo was determined as follows: carbonate-bound>exchangable> Fe-Mn oxide>residual>organic matter. The order of decreasing bioavailability of detected heavy metals in sediment fractions from Ile-Ife was determined as follows: carbonate-bound>organic matter> Fe-Mn oxide>residual>exchangeable.The bioavailability percentage of free metal ions and organic-bound metal fractions in Osogbo were as follows: 46.42% Pb, 30.70%Cd, 32.96%Mn, 36.00%Ni; 33.00%Pb, 36.00%Cd, 35.00%Mn, and 31.58%Ni and the bioavailability percentage of free metal ions and organic-bound metal fractions in Ile-Ife were as follow: 35.71%Pb, 26.92%Cd 36.31%Mn,36.00%Ni; 33.00%Pb, 32.00%Cd, 36.73%Mn and 31.58%Ni respectively. Results indicate that the runoff sediments in Osogbo were primarily polluted with Pb and Cd and that Ile-Ife runoff sediments were primarily polluted with Cd. The runoff water samples from the two towns were contaminated with varying concentrations of the analysed heavy metals, though concentrations were all determined to be less than the permissible limits of metals in drinking water.
- Keywords
- Chemical Fractionation; Heavy Metals; Sediment; Runoff
- StartPage
- 60
- EndPage
- 74
- Doi
- 10.5963/IJEP0601005