SELECTED HEAVY METALS CONCENTRATION IN SOME VEGETABLES CULTIVATED USING INDUSTRIAL WASTEWATER IRRIGATION

Abstract

This study was conducted to assessing of selected heavy metals (Cr., Cd, Zn, Hg and Pb) accumulation in the edible portions of cabbage, tomato and onion cultivated around Wonji in eastern part of Ethiopia. The concentrations of the same heavy metals were determined in water samples collected directly from industry discharge and also three irrigation sites Varied between sampling points. Vegetable Samples were first optimized through wet digestion procedure and contents of heavy metals were analyzed using atomic absorption spectrometry (AAS). In Kuriftu samples, value of Chromium (Cr) in descending order was that concentration in cabbage > onion > tomato, Cadmium (Cd) concentration in Cabbage > tomato > onion, Lead (Pb) concentration in onion > tomato > cabbage, mercury (Hg) in tomato > onion> cabbage and Zinc (Zn) concentration in tomato > cabbage >onion. In Melkahida samples, concentration of Chromium (Cr) in onion > cabbage > tomato. Cadmium (Cd) concentration in Cabbage > onion > tomato, Lead (Pb) concentration in onion > tomato > cabbage, mercury (Hg) in tomato>onion>cabbage and Zinc (Zn) concentration in cabbage > onion > tomato. In Awash Melkassa samples, concentration of Chromium (Cr) in onion > cabbage > tomato. Cadmium (Cd) concentration in onion > cabbage > tomato, L ead (Pb) concentration in cabbage > onion > tomato, mercury (Hg) in tomato > onion > cabbage and Zinc (Zn) concentration in cabbage > tomato> onion. Concentrations of heavy metal in each vegetable showed significant difference between the three farming sites. In tomato, for example ːChromium (Cr) concentration ranged from 0.27 mg / kg in Awash Melkassa to 0.65 mg /kg in Kuriftu Cadmium (Cd) ranged from 0.26 mg / kg Awashmelkassa to 0.97mg/kg in Kuriftu Lead (Pb) ranged from 0.14 mg / kg in Awashmelkassa to 0.34mg/kg, in Kuriftu Zinc (Zn) ranged from 7.94 mg / kg in Awashmelkassa to 12.41 mg / kg in Kuriftu Similar trend was also observed when cabbage and onion are considered. In water samples values of the tested heavy metals also varied between sampling points. Overall, results of this study showed that heavy metal concentrations measured in irrigation water and vegetables were above the limit