Ecological risk assessment of some heavy metals in roadside soils at traffic circles in Gombe, northern Nigeria

M.B Sulaiman,A.H Santuraki,A.U Babayo

doi:10.4314/jasem.v22i6.26

Abstract

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 Geoaccumulation 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. Keywords: Assessment, Ecological risk, Heavy metals, Roadside soil

Highlights

Public motor roads affects natural environment to a large extent because automobile act as line sources of heavy metal pollutants (Poszyler and Czemiak, 2007)
The results of Pb (15.1 - 650 mg/kg) reported by Onianwa (2001), was higher than the Pb concentration recorded in the soil samples from edge of roadside while the Cd (0.02 - 2.71 mg/kg) concentration in the present study were higher than the values reported
The soil sample from edge roadside at MTC recorded the highest concentration of Zn (101.0 mg/kg) while soil sample at UTC recorded highest the concentration of Cu (38.00 mg/kg) and lowest concentration of Zn and Cu was recorded at 50 m distance UTC (58.10 mg/kg) and at 50 m distance MTC (18.50 mg/kg) respectively

Summary

Introduction

Public motor roads affects natural environment to a large extent because automobile act as line sources of heavy metal pollutants (Poszyler and Czemiak, 2007). Considerable attention has been paid to the vehicular exhaust and road dust/soil, the pollution of the roadside soils by heavy metals from automobile source is a serious environmental issue (Ma et al, 2009; Aslam et al, 2011; Lu et al, 2012). Heavy metal contamination in roadside has been a worldwide environmental concern with its potential ecological effect (Hu et al, 2017). This current study aims to evaluate the levels of some heavy metals in the roadside soils at different traffic circle in Gombe metropolis with a view of providing information on the extent of the pollution and overall ecological risk of metals in the soil to the local environment

Methods

Results

Conclusion