Heavy metal pollution along the highway area with the method of geo-accumulation index

Objective To assess the pollution of the heavy metals in the soil along the highway area caused by traffic. Methods The smaples of the farming soil were collected along the section of the highway No.320 in Malong city .Heavy metals such as Cu,Cd,Pb,Zn,Cr,As and Ni were determined by atomic absorption spectrophotometry and spectrphotomter,samples from a control section were also collected,the method of geo-accumulation index was used for detection. Results The content of Cu,Cd,Pb,Zn,Cr As and Ni in the soil of the observed area were obviously higher than those in the control section (P0.01). The pollution was ranked as medium to high level for Cd, medium for Pb, and light to medium for Cr and Cu. The pollution spread to an extent of around 150 m,and the concentration decreased gradually. The soil pollution of the heavy metals was in the following order: CdPbCrCuAsZnNi.Conclusion Cd,Pb and Cr were the major heavy metals polluting the soil along the highway and the source of pollution was the heavy metals from the exhaust fume, tires and mechanical parts of the automobiles.