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Concentration of Some Metals in Soil Samples Collected from Different Parts of Ethiopia

Abraha Gebregewergis

The amounts of some metals (K, Ca, Mg, Fe, Mn, Zn, Cu, Cd, and Pb) in the soil samples collected from the three different areas of Ethiopia (Bahir Dar, Bure and Debre Markos) were determined by using the Microwave Plasma-Atomic Emission Spectroscopy (MP-AES). After proper sample pretreatment, 5 mL HNO3: 1 mL HClO4, 240°C and 2:30 h were the optimized digestion conditions. The results showed that the mean concentration of the Fe content of the soils is the highest of all the other studied metals in all of the three sampling areas. The overall mean concentrations of the metals collected from the three sampling areas in mg/kg can be ordered as Fe (74089 ± 3)>Ca (4484 ± 3)>K (3567 ± 3)>Mg (1239 ± 1)>Mn (1196 ± 3)>Zn (152 ± 2)>Cu (39.0 ± 2)>Pb (4.20 ± 0.6)>Cd (2.10 ± 0.2). There was a significant difference between the metal concentrations of the soils collected from the three sampling areas at a confidence level of 95%. On the other hand, the soil samples were not free from the level of the toxic heavy metal Pb and Cd ranges from 3.10-5.25 mg/kg of Pb and from 1.09-3.14 mg/kg of Cd collected from the three sampling areas. The accuracy of the optimized procedure was evaluated by analyzing the digest of the spiked samples with standard solution and the percentage recoveries were varied from 92%-104%, which was within the acceptable range of 100% ± 10%.