Assessment of Toxic Levels of Some Heavy Metals in Road Deposited Sediments in Suleja, Nigeria

Road deposited sediments contain toxic metals which can pollute terrestrial as well as aquatic environments when these pollutants are mobilized during storm run-off. Assessment of toxic metals in the road deposited sediments of Suleja streets was carried out. 30 samples were collected from seven selected streets. The road sediment samples were digested with a mixture of HNO3 and HClO4 (2:1 v/v), and analyzed for the metals Pb, Cu, Cr, Zn, Cd and Ni using Atomic Absorption Spectrophotometer. Results showed that metal concentrations were in the order Zn>Pb>Cu>Ni>Cd>Cr. Geo-accumulation Index indicated that the contamination degree ranged from unpolluted to moderately polluted areas. Potential Ecological Risk Index demonstrated that overall risk caused by metals ranges from moderate to low. Only Cd constitutes considerable risk and contributed 60.15% of the total risk.