Cow dung used as soil amendments and a sequential chemical speciation (six steps) procedure were used to predict the uptake of Cr, Cu and As by maize (Zea mays) plant in chromated copper arsenate (CCA) contaminated soil. A pot experiment containing the contaminated soil samples with different percentage levels of amendments and control (no amendment) was set up. The relative concentrations of the metals in the CCA contaminated soil were established as Cr 265.84 mg/kg, Cu 155.82 mg/kg and As 33.09 mg/kg. However, with the use of speciation and calculations based on mobility factor (Mf), the relative toxicity of the metals in the soil was established as As (60%) > Cr (19%) > Cu (8%). The amendment, rich in organic matter raised the pH level of the soil, demobilized the metals rendering them unavailable through bounding resulting into relatively lower uptake by plants in soils with amendment when compared with plants in the control pots.
Key words: Chromated copper arsenate CCA contaminated soil, amendment, copper, maize (Zea mays).
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