Heavy metal concentration in soil and maize (Zea mays L.) in partially reclaimed refuse dumpsite 'borrow-pit' in Port Harcourt, Nigeria

Limited farmland in urban and semi-urban areas in Nigeria is compelling city dwellers to cultivate crops in poorly reclaimed lands, including refuse filled borrow pits. This research assessed the heavy metal concentration in soil and maize harvested from a partially reclaimed refuse dumpsite ‘borrow-pit’, located at Egbelu-Minita community, East-West Road of Port Harcourt, one of Nigeria’s seven metropolitan cities. Spatial and temporal samples of three media (surface water, soil and maize) from the partially reclaimed section of the borrow pit were analyzed for copper (Cu), zinc (Zn) and lead (Pb). The resulting datasets were analyzed statistically and the means compared. The order of concentration of the metals in soil was Zn>Cu>Pb; 9.8±1.25, 0.23±0.50, 0.04±0.07 mg/kg, respectively. In maize, the highest concentrations of Zn, Cu and Pb were recorded in the root and stalk. The concentrations of Zn, Cu and Pb in the maize grains were within safe limit set by FAO/WHO, but potential human health implications subsist from continuous consumption of crops harvested from the borrow-pit. Innovative and cost-effective waste management practices integrated into the residential waste disposal system are imperative to minimize heavy metals contamination of soil, surface and groundwater and food resources.