Soil properties in the metropolitan region of Ibadan, Nigeria: implications for the management of the urban environment of developing countries

This paper examines the variation in the properties of surface soils from the rural, through sub-urban, to the urban zones of Ibadan metropolitan area, south-west Nigeria. Soils were sampled at 0–20 cm depth in the northern part of the metropolis. Statistical techniques were used to compare the data obtained in the three zones. The results of the analyses clearly show that the mean values of nine out of the eighteen soil properties analysed differed significantly between the three zones. In particular, the concentration of two of the three heavy metals analysed in the study, that is, zinc and lead were higher in the urban zone than in the other two zones. The accumulation of heavy metals in the soils of the urban environment of developing countries requires urgent attention from environmentalists and urban development planners. It is important to prevent such heavy metals leaching into the underground water supply, and, to minimise the health risks to both humans and animals that depend solely on this source of water supply.