ASSESSMENT OF HEAVY METALS CONCENTRATION IN TANNERY SOLID WASTE AND SOIL AT THE DUMPING SITE IN MOJO TOWN, CENTRAL ETHIOPIA

Abstract

Tannery industry considered to be one of the polluting industries in case of water, soil and air due to the deferent types of chemicals used in transforming hide to leather. The study was conducted in order to determine the concentration of heavy metal of Chromium, Iron, Zink, Nickel, Manganese, Lead, Copper and Cadmium and particle size distribution of tannery solid waste and tannery dumping site soil. The sample was selected purposively and analyzed for the presence of heavy metal using atomic absorption of spectroscopy and Bouyoucos hydrometer method was used for soil particle size. Microsoft excel was used for analyzing of metals and presented in tabular and graph form. Dumping site and control soil was sandy loam and sandy clay loam. The result shows that the leather sample and other waste products of tannery solid waste have significant amounts of heavy metal. The concentrations of Cr, Fe, Zn, Ni and Mn for solid waste were 78mg/kg, 23.6mg/kg, 8.6mg/kg, 3mg/kg and 13mg/kg and for dump site soil of 0-20 and 20-40 were 4 and 2mg/kg, 50.2and49.4mg/kg, 21.4and19.5mg/kg, 14and10mg/kg and 35.916and35.166mg/kg and for control sample 3 and 2mg/kg, 44.4and 45.8mg/kg, 19.7and15.5mg/kg, 10 and6 and 29.75 and26.83mg/kg was observed. Chromium show higher value in solid wastes. There are considerable downward movements of heavy metal in to soil profile but not exceed the upper layer of soils. All metal was lower than maximum permissible limits, while Pb, Cd and Cu were not detected by AAS. Generally, the result shows that there was an increase in the concentration of heavy metals in the dumpsite soils than that of the soils at the control sites. Therefore, Tannery solid waste dumping sites contained high concentrations of heavy metals which are later absorbed and accumulated by the plants growing within such site for this the appropriate measure should be taken.