Ecological Risk Assessment of Some Heavy Metals in Roadside Soils at Traffic Circles in Gombe, Northern Nigeria

The study evaluated the levels of some heavy metals in the roadside soils at different traffic circles using geo-accumulation index, ecological risk and Hakanson method to assess the overall ecological risk and identify ecological potential risk of heavy metals pollution. The top soil samples were collected at three different traffic circles from edge and at 50 m distance from the roadside, and analysed for heavy metal (Pb, Cd, Cu and Zn) using atomic absorption spectrophotometer. The mean concentrations of heavy metals (mg/kg) ranged from (15.0 - 45.07) Pb, (0.35 - 2.60) Cd, (19.05 - 38.0) Cu and (58.10 - 101.0) Zn. The abundance of metals was found in declining order: Zn > Pb > Cu > Cd. The metals concentrations were found to be higher in the soil samples from edge due to high traffic volume and human activities, and there was significantly decrease in concentration with increase in roadside distance. The Geo-accumulation index (I_geo) examined in this study revealed that soil samples from edge and 50 m distance from the roadside were polluted with cadmium. Ecological risk assessment carried out showed that the metals posed low ecological risk and cadmium contributed 66.63 - 94.21% of the total potentially ecological risk.