Analysis On Characteristics And Source Apportionment Of Polycyclic Aromatic Hydrocarbons(PAHs)in Atmospheric Particles PM2.5in Jinan

16PM2.5-bound PAHs samples were collected and analyzed during the four seasons from January to November in2011in Jinan to investigate the seasonal variations and sources. Besides, the concentrations of16PM2.5-bound PAHs indoor and outdoor during three pollution episodes and clean day from January12to February4in2013were analyzed to study the correlation between indoor and outdoor PAHs concentrations, daily variations and sources, furthermore, influence fectors of indoor PAHs were discussed. In addition, this study estimated the health-risk level using BEQ values and cancer risk level. The main conclusions were as follows:(1) During January to November in2011, total PAHs annual concentration in PM2.5ranged from1.94to92.19ng·m-3and showed obvious seasonal variations. PAHs concentrations during haze period in autumn and winter were higher than that in spring and summer, during January12to February4in2013, indoor and outdoorAHs concentrations were in the range of83.71-329.84ng-ni3,74.60～281.38ng·m-3respectively. During the haze episode, both indoor and outdoor PM2.5-bound PAHs concentrations increased rapidly, and most I/O values of4～5-ring PAHs ranged from0.80to0.95, approximated to1, indicating that haze pollution influenced the air quality directly. In fog and haze episode, PAHs concentrations level decreased in a way and remained stable, in that pollutants were difficult to spread in fog weather. Most I/O values were0.45～0.75, lower than1, since fog drops could improve pollutants removal efficiency in process of indoor and outdoor air convection and infiltration. The clean day after the fog and haze episode, PM2.5-bound PAHs decreased and remained low level. Combination Fog drops with atmospheric particulates conduced to deposition of PM so that fog could clean up air pollutants in a way. The I/O values of5-6-ring PM2.5-PAHS were0.85～1.21. Indoor and outdoor PAHs concentrations came near, even indoor pollution was worse than outdoor.(2) Diagnostic ratio (DR) analysis failed to find the obvious difference of PM2.5-bound PAHs between haze day and clean day. Diagnostic ratio (DR.) and principal component analysis (PCA) suggested that the PAHs in PM2.5were mainly derived from vehicle emission, coal combustion and biomass burning, and vehicle emissions occupied the highest contribution rate predominated by diesel vehicle emissions. The correlation analysis between indoor and outdoor PM2.5-bound PAHs concentrations featured the I/O values’daily variation, i.e. i (07:00-13:30)>ii (14:00-20:00)>iii(21:00-07:00), indicating that indoor air ventilation and human activities had a certain contribution to PM2.5-bound PAHs concentrations.2～3-ring PAHs concentration level primarily effected by outdoor sources with I/O>1, however,4-ring PAHs and5-6-ring PAHs were mainly derived from coal combustion and vehicle emission, respectively. Compared to outdoor environment, indoor4～6-ring PAHs concentrations were lower withI/O<1, since indoor and outdoor air convection and infiltration could remove the pollutants.(3) Meteorological conditions containing temperature, wind speed and relative humidity had an influence on PM2.5-bound PAHs concentration level The PM2.5-bound PAHs had a positive correlation with relative humidity, and a negative correlation with temperature, wind speed and visibility. Nevertheless, the correlation between PAHs concentrations and PM2.5mass concentrations was not confirmed.(4) The BEQ and CR value of PM2.5-bound PAHs characterized apparent seasonal variations, namely winter>autumn>spring>summer in Jinan The mean values of BEQ and CR observed during autumn and winter haze period were obviously higher than those of spring and summer haze day. Result showed that haze pollution in autumn and winter would seriously impair human health in Jinan. The daily variations of BEQ values in indoor and outdoor environment showed as i (07:30-13:30)>ii(14:00-20:00)>iii(21:00-07:00). The BEQ and CR values of the four episodes characterized as:values in winter commont haze episode were higher than those both in serious haze episode and fog and haze episode, however, values in clean episode were lowest. Except for clean episode, the others’ indoor BEQ and CR values were a little higher than outdoor, this is to say, the health-risk level of indoor environment was higher than outdoor. During this sampling period, BEQ values in Jinan were well higher than external cities. Even if compared to domestic cities, the level was still high. All CR values exceeded1×10-5meaning the minimum cancer risk level need to be focused on. The haze pollution would seriously impair human health during January to February2013in Jinan.