Assessment of Heavy Metal Contamination in Roadside Surface Soil in a Typical Vegetation Region of Suiman Highway

Concentrations of heavy metals(Pb, Cd, Cu, Zn and As) were investigated in roadside surface soil under different types vegetation along the Hailin-Yabuli road of national highway 301 in Heilongjiang province. Soil samples (297)were collected at different distances(0-100m) on the downwind sides along the road. The contamination of heavy metals in the soil samples was determined. The results showed that the average concentration of 5 elements were universally higher than the local background value. The average concentrations of five elements were not remarkable difference. The status of soil pollution by heavy metals was evaluated by using single factor pollution index(Pi) and integrated pollution index. The roadside surface soil was lightly polluted by Cu, Pb, Zn and As, the soil of typeⅠwas seriously polluted by Cd and typeⅡand typeⅢ was moderately polluted by Cd. Correlation analysis indicated that the traffic and construction of road absolutely impacted the contamination of Pb, Cd and Cu in the roadside soils. Main pollution extents of the soil showed that the soil of typeⅠdid not extend much beyond 40-60m, and the soil of typeⅡand typeⅢ did not extend much beyond 70-100m.Complex structure forest belt can prevent of pollutant dispersion and reduce the impact from road and traffic, but simple arbor forest belt do not reduce the effect by the traffic pollution.