Iranian Journal of

Background and Objective: Street dust is considered as one of the important sources of particulate matters and heavy metals in the atmosphere. The goal of this study was to assess the heavy metals pollution in street dust of Tehran and evaluate their ecological risk.
Materials and Methods: The sampling of street dust was carried out in two areas at the east and west of Tehran. After preparation of samples, the concentration of heavy metals was measured by ICP-MS. The pollution level of heavy metals in the street dust was assessed using geo-accumulation index (Igeo), pollution index (PI), integrated pollution index (IPI), enrichment factor (EF) and ecological risk index (RI).
Results: The results of the calculations of the indices showed that the street dust in both studied areas was non-polluted with Li, Al, Ti, V, Cr, Mn, Fe, Ni, Sr and Ba. The origin of these elements was mainly natural sources. However, Cd, Cu, As, Zn, Sn and Pb had medium to high level of contamination. These elements had a very high to extremely high enrichment in both areas. Their origin was mainly anthropogenic sources. The ecological risk index indicated a moderate ecological risk for the east and a low ecological risk for the west area.
Conclusion: The higher level of lead in the East is the main reason of higher ecological risk of this area. Therefore, the heavy metals pollution of the street dust, especially lead and its enterance into the environment, should be considered in this area.
 

Results: The mean concentration of heavy metals was as follow: Pb (251.20), Ni (94.6), Cu (75.80), Zn (132.84), Cd (0.69), V (4.97) and Cr (141.48) (mg/kg). The average value of enrichment factor in the soil samples decreased as Pb>Ni>Cu>Cr>Zn>Cd>V. Nemrow integrated pollution index (NIPI) indicated high level of pollution for the studied heavy metals except V. The Potential ecological risk of the studied heavy metals showed a low potential ecological risk for V, Cd, Zn and Cr; Cu showed a moderate risk and Ni and Pb indicated a considerable ecological risk. The mean value of the risk index indicated that 27 (55.10%) of the soil samples with a moderate risk, 21 (42.85%) with a considerable risk and one sample (2.05%) with a high ecological risk.
Conclusion: The obtained results from the enrichment factor, Potential ecological risk, and risk index indicated that the main source of heavy metals in the study area were anthropogenic sources such as oil drilling activities.