Determination of some Major and Trace Metals Levels in Onion (Allium Cepa L.) and Irrigation Water Around Meki Town and Lake Ziway, Ethiopia

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Addis Ababa Universty


The levels of major (Ca and Mg) and trace (Cu, Co, Cr, Mn, Zn, Cd and Pb) metals were determined in onion (Allium Cepa L.) bulbS and well water and Lake Ziway water employed for irrigation were determined by flame atomic absorption spectroscopy(FAAS). Sample dissolution of onion was carried out by wet digestion with a total volume of 2 mL HNO3 (69-72 %) and 2 mL HClO4 (70 %) mixture in flask fitted with reflux condenser on Kjeldahl heating apparatus. Higher levels of Ca (599 and 550 μg/g) than Mg (516 and 407 μg/g) in onion irrigated with well and Lake Ziway water, respectively were detected. Among trace metals, the highest level was that of Zn (18 and 14.1 μg/g) followed by Mn (8.8 and 13 μg/g) Cr (4.9 and 6.6), Cu (3.2 and 3.6 μg/g), Co (1.2 and 0.8 μg/g) and Cd (0.64 and 0.53 μg/g) in onion irrigated with well and Lake Ziway water, respectively all in dry weight basis. Lead was below detection limit of the analytical procedure in this study. The levels of Ca and Mg detected in well water and the Lake Ziway water used for irrigation were (22.7, 9.9) and (30.2, 8.6 mg/L), respectively. Higher levels of Zn (0.08 mg/L) and Co (0.06 mg/L) were found in the lake water while higher Mn (1.1 mg/L) and Cr (0.44 mg/L) were determined in well water. Cu, Cd and Pb were below the method detection limit in both well and Lake Ziway water samples of the study area. Mn in well water and Cr in both water exceeded the FAO limit of maximum recommended level in irrigation water. Key words: Onion (Allium Cepa L.), irrigation water, Lake Ziway, FAAS and wet digestion



Onion (Allium Cepa L.); irrigation water; Lake Ziway; FAAS and wet digestion