Abstract

Poultry droppings 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 contaminated soil samples to different percentage levels of amendments and control (no amendment) was set up. The initial concentration of Cr, Cu and As in the contaminated soil sample were established. The six fractions based on sequential extractions were also established. The distribution patterns of the metals based on their mobility factor M_f showed values high enough to predict high lability and bioavailability for arsenic, moderate for chromium and low for copper. The amendment, an energy-rich source substance enhanced mobility and bioavailability of the metals and their subsequent uptake and accumulation in the maize plant. This led to a cleanup at 20% amendment of As (20.6%), Cr (2%), and Cu (17.1%) after a period of twenty days. These figures are impressive considering the fact that the increase in pH occasioned by the poultry dropping amendment must have bound the metals.

Key words: CCA contaminated soil, amendment, copper, maize (Zea mays).