Assessment of Traffic Related Heavy Metals Pollution of Roadside Soils in Emerging Urban Centres in Ijebu-North Area of Ogun State, Nigeria

This study investigated the concentration of eight critical heavy metals in the roadside soils of selected urban centres in Ijebu-North Local Government Area of Ogun State, SW, Nigeria. Thirty-six composite soil samples were collected along the roadside based on distances to the roads. Physiochemical properties and concentrations of heavy metals (Cd, Cr, Cu, Fe, Mn, Pb, and Zn) in roadside soils in some selected locations were determined using atomic absorption spectroscopy. Accumulation of heavy metals in top soils is greately influenced by traffic volume and all the heavy metals exhibited a significant reduction in the roadside soils with increasing distance from the road. Metal concentrations in the roadside soils followed order of Zn>Pb>Fe>Cu>Mn>Cd>Cr. Concentration of Zn was 156.09 mg/Kg in roadside soils of Ijebu-Igbo/Oru/Ago-Iwoye which is experiencing high volume of traffic , while it ranged from 10 – 47 mg/Kg for Ijebu-Igbo/Bajowa/Akanran road with low traffic volume. Pb concentration of 26.7 mg/Kg was observed in : Ijebu-Igbo/Oru/Ago-Iwoye road especially in centre of the city. Concentration of all heavy metals examined were below the EU guideline, however, the paper suggested a regular monitoring and assessment to ensure sustainable management of the urban environment and reduction of traffic-related contamination of soil, plants and water.

Keywords
Heavy metal; pollution; roadside soils; transportation; monitoring; vehicular emission; Ogun State; Nigeria