Investigation of contamination and spatial variations of Pb and Cd, a case study of the route between Zabol and Zahedan

Soil contamination produced by Cd and Pb released from vehicles is a serious environmental problem. Lead as a result of using leaded petrol fuels and cadmium in the car tire is introduced into the environment through vehicle depreciation and traffic. This study aimed to investigate the spatial distribution of heavy metals such as Pb and Cd at the roadside soils of Zabol - Zahedan route. 252 soil samples were taken from a depth of 0 -20 cm and the concentration of total lead and cadmium metals, physicochemical properties of soil including pH, EC and organic matter were measured. The contamination assessment of soil was done through using enrichment factor and geoaccumulation index. Metals’ spatial distribution maps for heavy metals concentration were used kriging methods. The mean concentration at 0, 50 and 100 meters, respectively, was 2.12, 2.03 and 2 mg kg-1 for lead, which is less than the global mean (25 mg kg-1) for this metal, and respectively 0.21, 0.21 and 0.20 mg kg-1 for cadmium, which was lower than the global average (0.53 mg kg-1). The results of the geospatial analysis showed that both variables were anisotropic and the exponential model for lead and Gaussian model for cadmium had the best fit.