Seasonal changes, identification and source apportionment of PAH in PM1.0

The objective of this research was to evaluate the seasonal variation of PAHs in PM1.0, as well as to identify and quantify the contributions of each source profile using the PMF receptor model. PM1.0 samples were collected on PTFE filters from August 2011 to July 2013 in the Metropolitan Area of Porto Alegre, Rio Grande do Sul, Brazil. The samples were extracted using the EPA method TO-13A and 16 Polycyclic Aromatic Hydrocarbons (PAHs) were analyzed using a gaseous chromatograph coupled with a mass spectrometer (GC-MS). Also, the data discussed in this study were analyzed to identify the relations of the PAHs concentrations with NOx, NO, O3 and meteorological parameters (temperature, solar radiation, wind speed, relative humidity). The results showed that in winter, concentrations of total PAHs were significantly higher than in summer, thus showing their seasonal variation. The identification of emission sources by applying diagnostic ratios confirmed that PAHs in the study area originate from mobile sources, especially, from diesel and gasoline emissions. The analysis by PMF receptor model showed the contribution of these two main sources of emissions, too, followed by coal combustion, incomplete combustion/unburned petroleum and wood combustion. The toxic equivalent factors were calculated to characterize the risk of cancer from PAH exposure to PM1.0 samples, and BaP and DahA dominated BaPeq levels.