METAL CONCENTRATIONS OF SOME VEGETABLES IRRIGATED WITH INDUSTRIAL LIQUID WASTE AT AKAKI, ETIDOPIA

Abstract

Plant analyses of leaves at maturity of some vegetables from
Akaki, were conducted to determine their heavy metal concentrations and resulting risk to human life. These vegetables; namely, swiss chard (Beta vulgaris var cicla L.), onion (Allium cepa L.), potato (Solanum tuberosum L.), cabbage (Brassica oleracea L. var capitata), and red beet (Beta vulgaris L.) were irrigated with industrial liquid waste from the Akaki Textile Factory, which is directly drained into farmlands. At present, Cd, Cr, Cu, Hg, Ni and Zn contents
of potato have surpassed maximum limits expected under normal unpolluted circumstances. The same is true for Cr in onion and red beet. Concentrations of Hg also exceed maximum expected tolerable levels in all vegetables. Copper and chromium are particularly the metals requiring attention. Total chromium -and nickel contents of the uncontaminated Akaki soils also are in the toxic range. The bio-availability of most of the metals is restricted because the pH of the soil
is in the weakly to medium alkaline range, which normally reduces the activity of most metals. Conclusively, metal concentrations at the moment have not yet reached phytotoxic levels, and hence the condition is now safe for human health, but as long as no measures are taken to avoid irrigating with the industrial liquid waste, the current trend indicates that the hazard to life will definitely rise after a certain period of time.