Study on heavy metal pollution along expressways

The contents of Cu, Pb and Zn along both sides of Xi´an-Baoji Expressway and Xi´an-Huxian Expressway in Shaanxi Province have been studied. The findings show that there is a tendency of early increase and later decrease in the contents of heavy metals with the increase in transverse distance from the axis of an expressway, the high content exits at a distance of 25-50m from the axis, and it decreases to the background level at a distance of 50cm from the axis; their transverse and longitudinal transfer and transformation capacities are different, among which Zn is the strongest in the transverse direction and the weakest in the longitudinal direction; the evaporation tank is of great importance in collecting the heavy metals along the highways.