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Global Research Journal of Agricultural and Biological Sciences Vol.3(5) pp.373 –380 December 2012.
Available online http://www.globalresearchjournals.org/?a=journal&id=grjabs
Copyright ©2012 Global Research Journals
Full length Research.
Investigation of some Heavy Metals in Citrullus vulgaris, Cucumis sativus and Soils obtained from Gardens being Irrigated with Wastewater in Maiduguri, Nigeria
E. I. UWAH* and V. O. OGUGBUAJA
Department of Chemistry, Faculty of Science, University of Maiduguri, P.M.B. 1069, Maiduguri, Nigeria
*Corresponding Author’s Email: uwahemmai@yahoo.com, Phone: 08028251882.
Abstract
The levels of some heavy metals (As, Cd, Cr, Cu, Fe, Mn, Pb, Zn and Co) were determined in the edible portions of watermelon (Citrullus vulgaris) and cucumber (Cucumis sativus) irrigated with wastewater in Maiduguri, Nigeria. The metal levels in the vegetables as well as soils where the vegetables were cultivated were analyzed using Atomic Absorption Spectrophotometer. The metal levels in watermelon obtained from the Alau dam area ranged from 0.28 ± 0.05μgg-1 Cd to 46.03 ± 0.03 μgg-1 Cr. In the Gongulon area, the results ranged from 0.61 ± 0.03 μgg-1 Cd to 47.38 ± 2.85μgg-1 Cr. In cucumber obtained from the Alau dam area, the metal levels ranged from 0.06 ± 0.01μgg-1 Cd to 50.36 ± 0.96 μgg-1 Cr. In the Gongulon area, the results ranged from 0.14 ± 0.06 μgg-1 Cd to 53.75 ± 3.70μgg-1 Cr. The metal levels in the soils ranged from 0.56 ± 0.05μgg-1 Cd to 60.20 ± 0.70μgg-1 Fe. There were significant differences (p < 0.05) between the levels of the metals in the vegetables obtained from the sample areas and those of the controls which were not irrigated with wastewater. The differences in the levels of the metals in vegetables obtained from the sample areas and controls could be attributed to the use of wastewater in irrigating the soils, excessive usage of fertilizers and of course, the environmental factors in the areas. The levels of some of the heavy metals were lower than the established critical limits causing toxicity in plants and were lower than the FAO/WHO maximum limits (ML) of heavy metals in vegetables. However, the levels of highly toxic heavy metals like Cd, Pb and Cr were above the reported permissible limits. Consumption of these as food may constitute possible health hazards to the consumers at the time of the study.
Keywords: Citrullus vulgaris, Cucumis sativus, soil, heavy metals, wastewater, fertilizers, Atomic Absorption Spectrophotometry, Maiduguri.