Spatial distribution and degree of heavy metal pollution in urban roadside dusts from Sanandaj, Iran

Industrial activities and high traffic density are the most important heavy metal pollution sources in urban areas. Roadside dust created by atmospheric deposition can be one of the best indicators for heavy metal contamination levels. The present study reports the spatial distribution patterns and degree of heavy metal pollution (Cd, Cr, Ni, Pb, Zn, and As) in 50 roadside dust samples from urban areas of Sanandaj, Iran. For this purpose, sampling points were selected on different roads including primary roads, high roads, and main roads. The geographic coordinates of sampling points were recorded by the Global Positioning System (GPS). The geoaccumulation index (Igeo) and integrated pollution index (IPI) were used to present the heavy metal contamination levels. The results obtained by the geoaccumulation index suggest that the roadside dust samples were moderately contaminated with Ni and Cr, moderately to heavily contaminated with Pb and Cd, and heavily to extremely contaminated with As and Zn. The assessment of the data shows that 92% of all roadside dust samples had moderate pollution levels with an IPI of higher than 2, indicating that roadside dust in Sanandaj County has moderately been polluted by anthropogenic emissions. In order to compare the heavy metal concentrations in different parts of Sanandaj County, each heavy metal contamination was interpolated in a geographical information system (GIS). Heavy metal distribution maps showed the different hotspots of each pollutant that indicated high traffic density and industrial centers as the important factors affecting their concentrations in Sanandaj County