Abstract

The purpose of this study was to determine the concentration of selected metals (Fe, Zn and Cu) in vegetables and the soil contaminating levels due to irrigation, using Flame Atomic Absorption Spectrophotometer (FAAS). The wet digestion and sequential fractionation extraction procedures were employed to solubilize the metals from the collected samples. The results obtained from this study showed overall concentration of selected metals Fe, Zn and Cu respectively, in the range of (358.17 to 547.17), (45.63 to 62.46) and (10.20 to 15.07) (mg /Kg) in the edible parts of sampled vegetables whereas, concentrations (mg/kg) of the metals in the soil samples were found to be in the ranges of (12051 to 20065), (69.37 to 123.77) and (68.47 to 146.10) for Fe, Zn and Cu, respectively. The modified Tessier sequential extraction procedure was used to fractionate the above three metals from the soil samples into five fractions.  In this study the detected metals were predominantly concentrated in residual fraction (F5); zinc was mainly associated with the residual fraction (F5) (87.14 to 96.40%) which is highly stable. The mobility factors of Zn, Fe and Cu were 0.908 to 3.044, 0.216 to 0.443 and 0.314 to 1.968, respectively. The concentrations of Fe and Cu in the soil and vegetable samples were above the recommended limit of both WHO and FAO; also, Zn vegetable samples was above the limit. However, Zn for the soil samples was smaller than WHO and FAO recommended limit. Based on facts obtained from this study, it was suggested that  concerned official body (ies) take the necessary precaution measures to clean the polluted area.

Key words: Metals, sequential fractionation, soil, vegetables, quantity.