Investigating the Risk Assessment of Heavy Metal Contamination of Iron, Zinc, Iead, Cadmium, Chromium, Arsenic and Nickel in Falling Dust of Tehran Metropolis, Iran

Nowadays, the development of transportation industry and urban traffic has resulted in soil, water and air pollution. Tehran is also one of the polluted cities. In this air, heavy metals such as iron, zinc, lead, cadmium, chromium, arsenic and nickel enter the human body system through inhalation, leading to problems for citizens. The use of falling dust is known to be a suitable and effective method for monitoring and measuring air pollution. Therefore, in this study, the amount of heavy metals Fe, Cd, Cr, As, Ni, Pb, and Zn was measured in each of the 22 districts of Tehran to evaluate the amount of contamination. For this purpose, 88 sampling points were considered in the entire city. Sampling was done in three months of winter 1400. Samples of surface dust were collected using pen brushes from the side of the main streets. Then, after preparing the samples (including drying, powdering and digesting), the concentration of the desired heavy metals was measured using an ICP-MS device. Then the indices of enrichment factor (EF), contamination factor (CF) and Geoaccumulation Index (Igeo) were calculated. Finally, the results obtained from the concentration of the studied metals were used to present the spatial pattern of the concentration of heavy metals using GIS software and inverse distance weighting (IDW) technique. The results showed that the highest concentration of all types of metals belongs to the central, south and southeast parts of Tehran. Also, among different elements, iron and then chromium have the highest average amount of pollution.