Spatial distribution and contamination assessment of heavy metals in urban roaddusts from Urumqi,NW China

摘要

This study reports the spatial distribution pattern and degree of heavy metal pollution(Cd,Cr,Cu,Ni,Pb,Mn,Be,Co,Zn and U)in 169 urban road dust samples from urban area of Urumqi city.The spatial distributionpattern shows that Cu,Pb,Cr and Zn have similar patterns of spatial distribution.Their hot-spot areas weremainly associated with main roads where high traffic density was identified.Ni and Mn show similar spatialdistributions coinciding with the industrial areas, while the spatial distribution patterns of Co and U show hot-spot areas were mainly located in the sides of the urban area where the road dust was significantlyinfluenced by natural soils. The spatial distributions of Be and Cd were very different from other metals. The geo-accumulation index suggests that road dust in Urumqi city was uncontaminated to moderately contaminatedwith Cd,Cu,Ni,Pb,Mn,Be,Zn and U.The integrated pollution index shows IPIs of all road dust samples were higher than 1,suggesting that the road dust quality of Urumqi city has clearly been polluted byanthropogenic emission of heavy metals.Moreover,the spatial distribution pattern of IPIs also shows severaldistribution trends in the studied region.