EXAMINATION OF THE IMPACT OF DUMPSITES ON SOILS AND GROUNDWATERIN IKARE AKOKO METROPOLIS, ONDO STATE,NIGERIA

Abstract

Seven heavy metals (Cd, Cr, Cu, Ni, Pb, Fe and Zn) were analyzed in soils and groundwater sample collected from two dumpsites located within Ikare Akoko,the northern geographical district of Ondo State, south western part of Nigeria. The physiochemical properties (colour, electrical conductivity and the high anionic concentration)of the water samples analyzedshowed that the water samples collected from the dumpsites were polluted and could not be regarded as portable water. The heavy metal analysis of the water samples revealed that the water samples from these dumpsites were polluted with total Cr having the concentration of 0.12 ±0.37 and 0.32±0.07, Fe: 2.23±0.31 and 0.36 ±0.12and also Ni: 0.03 ±0.04 and 0.03 ±0.06 for the first and second dumpsites respectively whencompared with the control site and WHO standard. The physiochemical properties of the soils such as pH, electrical conductivity, soil texture, organic matter content and soil exchangeable bases were evaluated.The total concentration of heavy metal in soils sampled showed thatapart from the metals that their limit value are not indicated, all metals analyzed were higher than the control value but lower than the target value for Nigeria soils. The average totalconcentrations of heavy metal in the soils were in the order: Cd < Ni < Cr < Cu < Pb < Zn < Fe. Five stepssequential chemical extraction was also carried out to determine the biological availability of these heavy metals to plant and eco-toxicity. The result showed that the highest proportion of all the metals analyzed were associated with the residual fraction meaning that, the metals are naturally present in the soil. While considerable proportions were detected in the non-residual fraction which are said to be biologically available to pollute the environment.The average mobility of metals analyzed wasin the increasing other: Fe < Cr < Pb < Ni < Cd < Cu < Zn.The level of pollution was determined using pollution index. The result of the Contamination factors (CFs) shows that the dumpsites’ soils are highly contaminated withall the heavy metals analyzed. Pollution load index for both sites were greater than one, meaning that the soils in both dumpsites are polluted. The result of the enrichment factor (EF)shows that the soils are enriched with Cd, Cr and Ni.