DISTRIBUTION OF HEAVY METALS IN SOIL AND VEGETABLES OF SELECTED DUMPSITE AND SCRAP YARD IN AKURE, NIGERIA

Abstract

The levels of heavy metals contaminations of both soil and Plant were investigated at Igbatoro Dumpsite and scrap yard at Oke - Aro market, Akure, Nigeria. Sixdifferent heavy metals (Zn, Cr, Cd, Pb, Mn and Fe) were measured in Ten (10) samples for both soil and plants obtained from both sites namely D1-D5, S1-S5, PD1-PD5, PS1-PS5 (D= Dumpsite Sample, S = Scrapyard Sample, PD = Plant Dumpsite Sample, PS = Plant Scrapyard Sample). Control Samples were picked for both sites, both for the soil and plant. The sampling sites were considered because of the dismantling and burning ofelectronic, and household products to recover metals. The soil samples were air dried, pulverized and sieved through 2 mm mesh size in the laboratory. Physicochemical parameters were carried out on all the soil samples using standard procedures. Sequential and total extraction of metals was carried out on the soil samples; the plants samples were extracted by wet digestion method and the extracts were then analyzed using Atomic Absorption Spectrophotometer (AAS). The mean concentrations of the metals in soil samples ranged from 1.03 to 2.93, 1.01 to 2.11, 378 to 526.67, 0.70 to 2.40 and 2.08 to 4.12 (mg/kg dry weight) for Cr, Cd, Fe, Pb, and Mn respectively for the dumpsite while the mean concentration of metals at the scrap yard is as follows- 1.25 to 3.86, 1.83 to 4.84, 301.00 to 683.33, 0.50 to 5.89 and 2.29 to 8.50 12 (mg/kg dry weight) for Cr, Cd, Fe, Pb, and Mn respectively. At the dumpsite, the mobility factor (MF) values of the metals are in the decreasing order Fe > Mn >Pb > Cr> Cd, the mobility factor values of the metals in the Scrapyard sites differs from site dumpsite and following the order Cr> Pb > Cd >Mn > Fe {at both sites the concentration falls between moderately uuncontaminated to moderately contaminated for both the calculated enrichment factor and the geo- accumulation index for all the metals}. The mean values of the plant samples ranged from 0.02 to 0.42, 0.25 to 0.432, 10.92 to 71.00, 069 to 0.074 and 0.11 to 0.21 (mg/L) for Cd, Cr, Fe andMn respectively; and for the scrap yard the mean concentration ranges from 0.02 to