Polluting Characteristics Of Polycyclic Aromatic Hydrocarbons In Different Phase In Ambient Air Of Beijing

Atmosphere particles have been the primary air pollutants of the cities in recent years.Organic compounds in the Atmosphere particles do harm to the human health and theatmospheric quality. Because of its teratogenicity, carcinogenicity and mutagenicity,polycyclic aromatic hydrocarbons (PAHs) are more harmful to human health.Particles and gas-phase samples were collected separately during March to December2012, Beijing. Particles samples were collected in six different size,∞-10.2、10.2-4.2、4.2-2.1、2.1-1.3、1.3-0.69and <0.69μm.The samples were analyzed by extraction,purification, concentration and GC-MS.The results showed: the mass concentration of atmospheric particulate maters is259.7μg/m3; the seasonal change in concentration of particles is:winter>spring>autumn>summer， and the size distribution is: less than0.69μm>∞-10.2μm>10.2-4.2μm>1.3-0.69μm>2.1-1.3μm>4.2-2.1μm.15kinds of PAHs were measured, except Bghi in gas-phase. The mass concentrationof PAHs ranges from66.37to296.64ng/m3，the average is158.74ng/m3. Gas-phasePAHs accounted for65%of the total. The seasonal change is: winter>spring>autumn>summer. The average mass concentration of BaP is4.82ng/m3，particle-phase accountedfor91.3%.40%samples were beyond the bounds of GB3095-2012.Particle-phase PAHs gather in fine particles and high-ring more easily. Concentrationof PAHs increases with particle size decreasing. PM2.1contained more than80%of thePAHs.5+6-ring were dominant and accounted for43.3-51.6%, except for summer.2-ringand3-ring PAHs accounted for36.8-54.9%in summer.3+4-ring PAHs were more than90%in the gas-phase.PAHs phase distribution was mainly affected by absorption. The mass concentrationsof PAHs were decreasing while the temperature, relative humidity and UV index increases.Barometric pressure was contrary to the way.Through the source apportionment found that PAHs came from gasoline car+hightemperature heating source (41%), coal+diesel vehicles (20%) and combustion sources(39%).Health risk assessment of PAHs showed:∑16TEQ was13.56ng/m3, particle-phaseaccounted for88.2%;∑9MEQ was10.96ng/m3, particle-phase accounted for89.7%. The average lifetime cancer risks for adults and children were12.36×10-5and7.84×10-5respectively. The loss of life expectancy for adults and children was768.09min and487.26min.