Heavy Metal Concentrations around a Hospital Incinerator and a Municipal Dumpsite in Ibadan City, South-West Nigeria

Studies to determine the concentrations of heavy metals in the surrounding soils and bottom ash of a hospital incinerator and a municipal dumpsite were carried out in Ibadan City, South-West Nigeria from November 2010 to January 2011. Samples were analyzed for Pb, Fe, Cu, Zn, Cr and Ni using Flame Atomic Absorption Spectrophotometry. Data obtained were analyzed using ANOVA, Students T-test and Pearson correlation. Mean concentrations of heavy metals in the sampled soils at the incinerator were 185.22±72.88, 16.22±13.13, 69.11±54.26, 2.33±2.53, 22.48±21.00 and 0.58±0.30 for Fe, Cu, Zn, Cr, Pb and Ni respectively, mean concentrations in the incinerator bottom ash were 5357.52±4671.89mg/Kg, 938.2±428.42mg/kg, 10670±3852.44mg/kg, 72.96±15.14mg/kg, 427.2±197.69mg/kg and 34.78±11.69mg/kg for Fe, Cu, Zn, Cr, Pb and Ni respectively and mean concentrations in sampled soils of municipal dumpsite were 290.67±78.66mg/Kg, 7.86±1.68mg/kg, 132.87±39.40mg/kg, 2.58±1.48mg/kg, 14.52±6.76mg/kg and 0.79±0.26mg/kg for Fe, Cu, Zn, Cr, Pb and Ni respectively. ANOVA showed that Fe (F = 11.254), Cu (F = 5.678), Zn (F = 20.399) and Pb (F = 3.679) had significant variations with sampling site, with bottom ash having the highest concentrations. The concentrations of heavy metals from both locations were higher than in the control site, indicating pollution. The heavy metal contents of the soils analyzed were all below the USEPA standard limits. However, the bottom ash contained high levels of Zn and Pb, that exceeded the standard limits. There is a need to appropriately dispose off the bottom ash from incinerators.