LEVELS OF SELECTED TOXIC HEAVY METALS (Pb, Cd, Zn, Cu and Cr) IN SOIL, SURFACE AND GROUND WATER SAMPLES FROM MIDEGA WOREDA, EASTERN HARARGHE, ETHIOPIA

Abstract

Metal contamination in soil, surface and ground water is a major component in the determination of water quality. The concentrations of selected heavy metals (Pb(II), Cd(II), Cu(II), Zn(II) and Cr(VI)) in soil and water samples collected from Midega, Eastern Ethiopia were determined after digesting the samples using acid digestion method. The physico-chemical parameters like pH,conductivity, alkalinity and hardness of the water samples were determined using appropriate instruments. The standard solutions for the selected heavy metals were prepared from commercially available salts. Out of the five selected heavy metals cadmium and chromium were not detected in all samples. But the three metals namely lead, zinc and copper were detected by the instrument and their concentrations were found to be 0.06 – 0.28, 0.206 – 1.032 and 0.487 – 0.71 ppm in soil, respectively. In water, the concentrations of the detected metals were 0.804 – 4.131 and 0.415 – 0.507 ppm for zinc and copper, respectively. The accumulations of the detected heavy metals were in the increasing order of Pb ˂ Cu ˂ Zn. The results obtained were compared with guidelines for drinking water quality such as the Environmental Protection Agency (EPA) and World Health Organization (WHO) guidelines. The levels of the detected heavy metals were not beyond the maximum permissible limit