Document Type : Research Paper
Department of Natural Geography, University of Kharazmi, Tehran, Iran
Faculty of Law and Political Science, University of Tehran, Tehran, Iran
Physical Geography, Faculty of Geography, university of Tehran, Tehran, Iran
Faculty of Nursing and Midwifery, University of Shahed, Tehran, Iran
The study of heavy metals in dust fall is very important due to effects on human health. The purpose of the present study has been to determine the level of contamination and ecological risk of heavy metals such as Cd, Cr, Cu, Ni, Pb in the falling dust of Tehran city, and investigation spatial distribution of pollution on the studied stations. Dust fallout samples were collected using Marble Dust Collector (MDCO) from 28 different locations across the Tehran city, during the statistical period (from December 22nd, 2017 to June 21st, 2018). Contamination factor(CF), pollution Load index(PLI), The potential ecological risk coefficient(Er) and The potential toxicity response index(RI) were used to identify the level of contamination and ecological risk of heavy metals. The amount of (Cf), (PLI), (Er) and(RI) for the heavy metals in the dust fall in winter and spring 2018 followed the order of Pb>Cd>Cu>Cr>Ni. The concentrations of Lead, Copper and Cadmium in winter were significantly higher than those in spring. Stable air, temperature inversions and more heating devices are used in winter, causes that heavy metals are increased in this season. Areas located in the east of Tehran have the highest pollution and ecological risk in terms of cadmium, copper, nickel and lead. Most of the chromium contamination exists from the central areas to south of Tehran. Tehran's prevailing wind direction and Tehran's topographic pattern, mines, factories and industries located in the west and southwest of Tehran have main role in polluting Tehran's falling dust with heavy metals.