Seasonal Inventory of Heavy Metals on Vehicular Polluted Soils and Roadside Distance Supporting Arable Crop Production in Umuahia Metropolis, Nigeria

This study was conducted between February and September, 2018 to evaluate heavy metal concentrations of road dust soils supporting arable crop production along five major roads connecting the Umuahia Metropolis to surrounding cities. Thirty soil samples from five major roads were collected during the dry and wet seasons at 10 m, 20 m and 30 m distances from road edges. The heavy metals were analyzed using tri-acid digestion. The results showed that mean concentrations of the heavy metals varied widely and had significant different between the seasons, among the five major roads and usually, decreased with increased in distance from the road. Accordingly, the study indicates that, the relative sequence of abundance followed the order: Fe > Zn ≥ Pb > Cd > Cr ≥ Cu > Co > Ni > Se ≥ As. Higher content of the heavy metals was recorded during the dry season (83.94 mg kg-1 ) than the wet season (74.72 mg kg-1 ). Among the roads, higher content of the heavy metals was recorded in Uzoakoli road (105.50 mg kg-1 ) while, the least was recorded in Aba road (53.37 mg kg-1 ). Similarly, higher contents of the heavy metals were recorded within the distance of 10 meters (94.56 mg kg-1 ) while, the least was recorded in 30 meters (61.73 mg kg-1 ) away for the roadside. Since the roadside soils in Umuahia Metropolis are being extensively cultivated for agricultural production, proper biomonitoring of activities in the urban environment should be done as often as possible to enlighten the public on dangers of heavy metal pollutio