Seasonal Trend And Source Identification of Polycyclic Aromatic Hydrocarbons Associated With Fine Particulate Matters (PM2.5 ) In Isfahan City, Iran Using Diagnostic Ratio and PMF Model

Abstract Particulate matters (PMs) and their associated chemical compounds such as polycyclic aromatic hydrocarbons (PAHs) are important factors to evaluate air pollution and its health impacts particularly in developing countries. Source identification of these compounds can be used for air quality management. The aim of this study was to identify the sources of PM2.5-bound PAHs in Isfahan city, a metropolitan and industrialized area in central Iran. The PM2.5 samples were collected at 50 sites during one year. Source identification and apportionment of PAHs were carried out using diagnostic ratios (DRs) of PAHs and positive matrix factorization (PMF) model. The results showed that the concentrations of PM2.5 ranged from 8 to 291 µg/m3 with an average of 60.2 ± 53.9 µg/m3 whereas the sum of concentrations of the 19 PAH compounds (ƩPAHs) ranged from 0.3 to 61.4 ng/m3 with an average of 4.65 ± 8.54 ng/m3. The PAH compounds showed their highest and lowest concentrations in fall and summer, respectively. Applying DRs, suggested that the source of the PAHs were mainly from fuel combustion. The main sources identified by the PMF model were gasoline combustion (28 %) followed by diesel combustion (22 %), natural gas combustion (17 %), evaporative-uncombusted (13 %), industrial activities (11 %), and unknown sources (9 %). The results revealed that in addition to transportation and industrial activities, combustion of natural gas for heating systems as one of the PAHs source in PM2.5 should be managed in the metropolitan area.