Contamination and Ecological Risk Assessment of Lead in Roadside Soil and Dust in Ibadan Metropolis, Nigeria

Abstract

Vehicular emissions are common sources of lead contamination of roadside soils and dust especially in urban cities. This study investigates current metal levels in roadside soils and dust in Ibadan metropolis and the associated ecological risk assessment. Concentrations of Pb, Zn, Mn and Ni were determined from 234 each of soil and dust samples collected from high, medium and low traffic density locations. The result indicated metals to be in the following decreasing order Pb>Zn>Mn>Ni with lead levels more significant in soils compared to dust particularly along high traffic density locations. Comparatively, current metal levels in soils were higher than values reported for 19 years apart, an indication of extensive urbanization of the city over the years. Principal Component Analysis (PCA) coupled with Cluster Analysis (CA) revealed metal contamination of soils and dust was related to traffic density. Pearson’s correlation analysis showed a strong positive correlation between metals in soils and dust further confirming the source. Among the metals, lead showed a higher potential ecological risk than other metals in soils particularly along high traffic density locations. The current levels of lead in soils and dust call for concerted effort to avoid particulate lead exposure to residents and road users.