DISTRUBUTION OF HEAVY METALS ON DUMPSITE SOILS, PLANT AND NEARBY WATER IN IKIRE, NIGERIA

Abstract

Solid Waste Management has become a major environmental concern and a fast growing issue for developing cities and countries in the world, including Nigeria. The study was carried out to determine the physicochemical, distribution of some heavy metals (Cadmium Cd, Chromium Cr, Lead Pb, Iron Fe, Copper Cu) at three major dumpsites and water samples in Ikire, Osun State, Nigeria. A total of 12 composite samples were collected at a depth of 0- 15cm at each dumpsite plus a control sample. The samples were air-dried, sieved and analysed. The physicochemical parameters (pH, electrical conductivity, chemical oxygen demand (COD), biochemical oxygen demand (BOD), dissolved oxygen (DO), total organic matter (TOM), cation exchange capacity (CEC), alkalinity, total hardness, sulphate, nitrate, phosphate, total solid (TS), total dissolved solid (TDS) and total suspended solid (TSD) were carried out on both water and soil samples using standard methods. Total metal concentration were determined after wet digestion by aqua-regia (HCl.HNO3-3:1) and the sequential extraction were determined using Tessier’s method. The metal concentrations were determined using d Atomic Absorption Spectrometer (AAS). The mean pH values for water samples ranged from 7.6±0.0 to 7.4±0.0 to 5.5±0.0 to 7.5±0.0 while the pH soil samples ranges from 7.5± 0.1 to 7.5 ±0.1 to 7.5± 0.0 to 7.6± 0.0 respectively, some of the dumpsites soils were slightly acidic with others were slightly alkaline. The total organic matter (TOM %) in soil of the studied sites ranged from 10.34±1.92 to11.22±1.56 to 9.51±3.16 to 3.44±0.01 respectively.The silt texture was found to be sandy on the study sites. The mean of total heavy metals concentration (mg/kg) of the soil ranged from 0.35±0.07 to 9.31±0.08, 33.00± 0.53 to 143.27±2.56 , 1.89±0.09 to 38.96±0.07, to 11873.00±111.10 to 20671.00±285.32, 6.29±0.27 to 101.62±1.11 for Cd, Cu, Cr, Fe and Pb respectively. However, the total heavy metal concentration in water for the study sites ranged from 0.00±0.00 to 0.03±0.01, 0.00±0.00 to 0.08±0.02 to 0.01±0.01 to 0.24±0.03, 0.00±0.00 to 0.11±0.00 for Cd, Cu, Cr, Fe and Pb respectively. Considering the total metal contents, the mean levels (mg/Kg) of Fe and Cu obtained from the soils collected shows that they are not significantly different (p>0.05). Higher amounts of Cd, Cu, Cr, Fe and Pb were found to be bound to Fe-Mn fraction, organic matter and residual fractions. The percentage distribution of metals in the dumpsites soils were higher than the one from the control site and they were in the order of Fe>𝐶𝑢>𝑃𝑏>𝐶𝑟>𝐶𝑑 respectively Cd and Cr were below the permissible limits when compared with the international guideline standards.