Abstract

I. Muazu¹, A. Uzairu¹, J.A. Kabgu¹, B.R. Issa² and M. M. Ndamitso³

The concentration of copper (Cu), Zinc (Zn), manganese (Mn), lead (Pb), Chromium (Cr) and Nickel (Ni) in various vegetables Viz, Lettuce, Sesame and Okra irrigated from the bank of River Challawa Kano, Nigeria were assessed using atomic absorption spectrophotometer. The concentration ranges of Cu, Zn, Mn, Pb, Cr and Ni in the leaves of lettuce and sesame were found to be from 3.20-6.40, 10.00-35.00, 9.00-19.00, 6.00-13.00, 8.00-19.00 and 5.00-10.00mgkg-1and 3.20-7.20, 9.00-28.00, 10.00-24.00, 2.00-6.00, 6.00-14.00 and 2.00-6.00mgkg-1 on dry weight basis, respectively. For okra fruits, the ranges were from 3.20-8.40, 8.00-20.00, 9.00-22.00, 3.00- 9.00, 4.00-13.00 and 4.00-9.00mgkg-1 dry weight. The mean concentration of Cu, Zn, Mn, Pb, Cr and Ni were found to be above the recommended maximum acceptable limits proposed by the Food and Agricultural organization (FAO), joint world health organization (WHO) / European Union (EU) and joint Food and Agricultural organization (FAO) and joint world health organization (WHO) experts limits. The mean concentrations of these metals determined in the study area were higher with the respective values of Cu(4.400mgkg-1), Zn(19.375mgkg-1), Mn(14.500mgkg-1), Pb(9.437mgkg-1), Cr(13.594mgkg-1), Ni(7.188mgkg-1) for lettuce while the vales for sesame and okra were; Cu(5.125mgkg-1), Zn(16.688mgkg-1), Mn(16.688mgkg-1), Pb(3.656mgkg-1), Cr(10.219mgkg-1), Ni(4.013mgkg-1) and Cu(5.947mgkg-1), Zn(13.594mgkg-1), Mn(14.469mgkg-1), Pb(5.875mgkg-1), Cr(8.969mgkg-1), Ni(6.188mgkg-1) respectively. These higher values in the samples compared with the control area might be attributed to the used of untreated effluents from tannery industries by the farmers for the irrigation of these vegetables. Thus, the high values of these heavy metals in the vegetable samples could put the consumers of these vegetables at health risk with time.

Heavy metals; Vegetables; Challawa river; Nigeria

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