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Distribution of Polycyclic Aromatic Hydrocarbons in Gas phase in urban atmosphere.

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Polycyclic Aromatic Hydrocarbons (PAHs) are toxic pollutants released by various urban combustion sources.Tehran is the largest city in Iran with a population of about 8 million and it is faced with serious air quality problems.The gas phase samples collected from 21 sites in Tehran area throughout year 2005. The samplesי PAHs were collected using a SKC trapping consisting of glass cartridge packed with XAD-2 resin supported by two polyurethane foam plugs. Sixteen PAHs were analyzed by HPLC with two detectors (fluorescence; UV-Vis) according to U. S. Environmental Protection Agency methods.The average concentrations of PAHs ranged from 16068.98 (mu)g/m^3 for Bahman site to 1000.24 (mu)g/m^3 for Nour site. The species that presented higher concentration were Acenaphtylene (2674.74 (mu)g/m^3), Naphthalene (2467.71 (muy)g/m^3) and Acenaphtene (1245.22 (mu)g/m^3). The PAHs with two and three rings were responsible by 87% of the total concentration among 16 PAHs.A major source of PAHs, in Tehran area is related to traffic and the number of gasoline and diesel vehicles.

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