ABSTRACT:

The accumulation and hence contamination of any environment with heavy metals remains an issue of great concern considering the toxic nature of these elements. Amongst other anthropogenic sources of these toxic substances, emission from vehicular traffic on highways also constitutes the predominant source of these metals especially in urban environments. It is in the light of this that this paper examined the relative accumulation of selected heavy metals (Pb. Cr, and Cd) between urban road corridors of high and low vehicular traffic. To identify the nature of the vehicular traffic on the road corridors. a temporal survey of traffic count was conducted by simple manual tally method. The average vehkular traffic carried by the roads justifies the classification of roads as high (12,991) and low (3,956) traffic corridors respectively. Then road dust samples were collected from seven sites over each of the road corridors. Next, background soil samples of about 50m distance away from the road were also collected from seven sites along the high traffic roadside. The collected samples were analysed by the atomic absorption spectrophotometry to determine the relative proportion or accumulation of the considered heavy metals along the high traffic and low traffic roads. The mean concentrations of the considered heavy metals: Pb, Cd, and Cr are relatively higher (800mg/kg, 11.80mglkg, and 17.82mg/kg) along the high vehicular traffic corridors in comparism to the low traffic corridors (328.57mg/kg, 1.31mg/kg and 5.94mg/kg) respectively. Also, the high traffic road dust samples showed significantly higher levels in the concentrations of Pb and Cd compared with the background soil samples taken 50m away from the road. The results of the study suggest that the road corridor with high vehicular traffic has the propensity to contaminate the environment than the low traffic road.