Road Construction and Vehicular Activities as Indicators for Heavy Metal Pollution in Osogbo Metropolis, South West Nigeria

The levels of heavy metals in soil samples from selected major roads under construction, burrow sites (a place where soil was obtained for road filling) and two roads under use have been investigated. Soil samples were collected and digested using standard methods. The digests were analyzed for Ni, Cr, Zn, Cd, Cu and Pb using Atomic Absorption Spectrophotometer. The data were subjected to descriptive statistics, non linear regression and one way analysis of variance (ANOVA). The results showed that cadmium had the highest Contamination Factor (CF). The Pollution Load Index of the roads under construction was higher than each of the Burrow siteand one of the Trunk C roads analyzed for comparison. The Ecological Risk Factor of the sampling sites was less than 40 which indicated that, the levels of heavy metals on the road construction sites did not pose ecological risks to the environment. The Ecological Risk Index of each of all the sampling sites was less than 150 indicating that they fell within the low ecological risk category. The study established that the Burrow site did not contribute to the heavy metal concentration of the road under construction and the contamination was traced to vehicular activities.