Abstract:

Urban street dust is one of the important indicators that reflects status of urban environmental pollution. The dust samples were collected in the district of traffic crossroads in Xianyang city. The experiment used atomic absorption spectrometry to measure lead, cadmium and copper of the dust content. Spatial technique was applied to study the content level and the spatial distribution character of heavy metal pollution in street surface dust of Xianyang city. Geochemical maps of heavy metals(Cd, Cu, Pb)in the street surface dust were produced based on and adopting Hakanson suggested potential ecological risk index technique to assess the potential ecological risk of heavy metals in street surface dust, and utilizing geographical information system(GIS)technique to draw up the spatial distribution map of assessment results. The results showed that the majority of heavy metals in the dust exceeded the soil background value in Xianyang city streets. The range of Cd, Cu and Pb contents in street dust is 0.09-0.2mg·kg-1, 68.82-1212.58 mg·kg-1 and 23.44-97.63mg·kg-1, respectively. Cu is 1-5.8 times of the soil background value in Xianyang. The contents of Cd and Pb are 0-1.7 and 0-2.6 times of the soil background value in Xianyang. Based on the calculation results of heavy metal ecological risk indexs in street surface dust of Xianyang, potential ecological risk of Cd is the highest, Cu is moderate and  Pb is the least. The ecological hazard for the different domains was in the order of industrial area > school area > business area > agriculture area. Generally speaking, heavy metals pollution in urban street dust of Xianyang reached the lightly ecological risk levels. The results are expected to provide important scientific basis for the urban environmental pollution control and city planning of Xianyang.

Key words: heavy metal, street surface dust, Xianyang city