Heavy Metals in Soils, Ash and Tridax Procumbens in the Vicinity of the University College Hospital Incinerator in Ibadan, South-West, Nigeria

Abstract

Heavy metal concentrations in soils and Tridax procumbens in the vicinity of the University of Ibadan College Hospital incinerator and in its bottom ash were determined. The concentrations of chromium, cadmium, lead and nickel were checked in soil and plant at some distances of 10m, 20m, and 30m away from the incinerator between June and August using atomic absorption spectrophotometry. There was a control site at 7km away from the incinerator. The mean concentrations of heavy metals in soils from the incinerator site were in the order: Ni > Cr > Pb > Cd. Concentrations of Cr, Cd, Pb, and Ni were highest at 10m from the incinerator. The mean concentration of Cr (42.90 ± 8.93mg/kg), Cd (4.40 ± 3.39mg/kg) and Ni (87.40 ± 8.98mg/kg) were however significantly higher at 10m from the incinerator when compared to the corresponding concentrations at the control site (p < 0.05). The mean concentrations of heavy metals in plant from the incinerator site were in the order Cr > Pb > Ni > Cd. Concentrations of Cr, Pb, and Ni in plant were highest at 10m from the incinerator while Cd concentrations were highest at 30m. The mean concentration of Ni (19.41 ± 12.65mg/kg) was however significantly higher at 10m from the incinerator when compared to the corresponding concentration at the control site (p < 0.05). Mean concentrations of Cr and Pb were higher in the ash when compared with concentrations in soil and plant samples. Heavy metal concentrations were however within the permissible limits specified by USEPA. Potential effect of the incinerator on the soil and plant around the area is minimal and might therefore present negligible impact on the population living around the area. However, there is a need to carefully dispose of the bottom ash to avoid the hazards of fly ash.