Heavy Metal Contamination of Roadside Soils of Northern England

Environmental pollution of heavy metals from automobiles has attained much attention in the recent past. The present research was conducted to study heavy metal contamination in roadside soils of northern England. Roadside soil samples were collected from 35 sites in some counties of northern England and analysed for four heavy metals (cadmium, copper, lead, zinc). Their concentrations and distributions in different road verge zones (border, verge, slope, ditch) were determined. Lead concentration was the highest in the soil and ranged from 25.0 to 1198.0 μg/g (mean, 232.7 μg/g). Zinc concentration ranged from 56.7 to 480.0 μg/g (mean, 174.6 μg/g) and copper concentration ranged from 15.5 to 240.0 μg/g (mean, 87.3 μg/g). Cadmium concentration was the lowest in the soil and varied from 0.3 to 3.8 μg/g (mean, 1.4 μg/g). Though the levels of heavy metals in roadside soils were higher as compared to their natural background levels in British soils, their concentrations in general, however, were below the 'critical trigger concentrations' for the contaminated soils. All the four heavy metals exhibited a significant decrease in the roadside soils with the increasing distance from the road. The border zone had the highest mean concentration of the four metals whereas the ditch zone exhibited the lowest mean concentration.