Distribution Pattern of Heavy Metals in Roadside Topsoils around the Rasht-Qazvin Freeway

Heavy metals are one of the main factors in pollution of soils around roads and highways. This pollution is a serious environmental problem worldwide. The metals are released by different ways, such as wear and corrosion of various parts of the vehicle and tires, as well as combustion. These products could contaminate roadside topsoil. Thus, the purpose of this research is to determine the contamination of roadside soil by heavy metals in the Rasht-Qazvin Freeway.
The 30 soil samples from 0-20 cm depth at three distances (0-5, 5-15 and 15-30 m) of roadsides were collected. Concentration of heavy metals in samples was measured using ICP-OES. The Ecological Risk Index was calculated for assessing the biological hazard level of metals in the soil.
Mean concentration of Zn, V, Cr, Pb, Cu, Co and Ni were 48.89, 46.63, 23.76, 20.05, 18.47, 11.11 and 9.48 mg kg-1, respectively. The results of potential ecological risk index showed that study area were of low ecological and biological risk.
Agricultural activities, climate conditions and vehicles traffic changes in the study area are important factors influencing the accumulation of heavy metals in the roadside topsoil. In order to pay attention to public health and food safety, it is suggested to evaulate concentration of heavy metals in agricultural products and rivers water in the study area.