Concentrations of Some Heavy Metals (Lead, Cadmium, Copper and Zinc) in High Traffic Density Roadside Soils in Selected Towns of Oromia Regional State, Ethiopia

Abstract

Environmental pollution of heavy metals from automobiles has attained much attention in the recent past. The present research was conducted to study heavy metal contamination in roadside soils of Oromia Regional State, Ethiopia. Roadside soil samples were collected from 4 sites (36 soil samples) and analyzed for the concentrations of four heavy metals (cadmium, copper, lead and zinc). Soil samples were collected at distance of 0, 25 and 50 m from the roadside. Lead concentration in soil samples was low and ranged from 0.31 to 0.91 mg kg-1. Lead analyses showed that there was no considerable contamination of soil in the study area. Cadmium concentration was the lowest in the soil and varied from 0.11 to 0.43 mg kg-1. Copper concentration ranged from 13.49 to 95.25 mg kg-1 and zinc concentration ranged from 42.30 to 97.70 mg kg-1. These concentrations were below the critical maximum levels above which toxicity is possible. In general, the levels of heavy metals in the roadside soils investigated were low. All the four heavy metals exhibited a decrease in the roadside soils with the increasing distance from the road.