Characterization andmetals fractionation of street dust samples fromTehran, Iran

Abstract

Fifty street dust samples were collected from Southern and Eastern parts of Tehran, the capitalof Iran. Samples were collected during summer under dry and stable weather conditions. Total concentrationsof copper (Cu), cadmium (Cd), lead (Pb), chromium (Cr), nickel (Ni), zinc (Zn), iron (Fe), manganese (Mn)and lithium (Li) were determined. Ten samples were then selected for characterization, metals fractionationand single stage extraction studies. X-ray diffraction (XRD) and X-ray fluorescence (XRF) were utilized tostudy the crystalline forms of metals and chemical compositions. In addition, sequential and single extractionprocedures were used to determine the concentrations of six heavy metals (i.e. Cu, Cd, Pb, Cr, Ni and Zn), andalso the mobility and bioavailability of elements. The risk assessment code (RAC) and IPOLLwere employed forthe risk assessment and pollution intensity of metals, respectively. Results showed that the single extractionprocedure could be used to estimate the total concentrations of most metals as an appropriate alternative fortotal digestion. The mobility and potential availability of metals in Tehran street dust followed the order of Cd> Zn > Pb > Cu > Ni > Cr. The risk assessment code results showed high risk for Pb, Cd and Zn and lowmediumrisk for Ni, Cr and Cu, and correlated positively with IPOLL result.