Metals in roadside soils of different grain sizes from high traffic roads in Kano metropolis, Nigeria

Abstract

Roadside surface soil samples were collected from 10 locations along high traffic roads and a control site between December 2009 and September 2010. The samples were analyzed for particle size distribution, pH, organic matter, electrical conductivity, cation exchange capacity, and the concentrations of Cd, Cr, Ni, Pb, Cu, and Zn in different grain sizes. Generally, the results show a decrease in the concentrations of all the studied metals during the wet season in the following order, Zn > Pb > Ni > Cu > Cr > Cd. Correlation of metal concentrations on traffic volume is low except for Pb; other sources seem to contribute significantly to the metal burden of the soil. The ecological risk index indicates that the roadsides of Kano metropolis are suffering from high metal contamination, though ameliorated by rain.

Keywords:

• roadside soils
• metals
• risk
• Kano metropolis

Acknowledgments

Special appreciation to Mu’azu and Khadijat, both of Chemistry Department Laboratory, Kaduna State University, for analyzing the samples. Thanks to Mal. Ahmad Mohammed of Kano Pollution Control Unit, Kano, Nigeria, for his assistance, especially in the field work. Staff of Chemistry Department, Ahmadu Bello University, is also acknowledged for the immense support given to realization of this project.