Distribution Characteristics of Polycyclic Aromatic Hydrocarbons in Atomspheric Particulates in the Area of the 3~(rd) West Ring Road in Beijing City

The airborne particles were collected in size grading at the 3rdwest ring road in Beijing City from March to December in 2012.The 16 priority PAHs in the samples were determined by GC-MS.The seasonal variation with concentrations of the total PAHs was observed.The results showed that the highest value of ρ(∑16PAHs) appeared in winter,followed by the order of spring autumn summer.Meanwhile,there were a linear dependence between ρ(∑16 PAHs) and ρ(PM).The PAHs were inclined to concentrate in the finer particles,the values of ρ 2.1(∑16PAHs) /ρ sum(∑16PAHs) accounted for 64%-87%.In general,4-ring and 5-ring PAHs were the main components in the seasons except summer.The finer the particles were,the higher-ring PAHs were.Principal component analysis and multiple linear regression(PCA/MLR) were applied to identify the source of PAHs in particles.The results showed that PAHs in airborne particulates mainly came from the emission of vehicle engines and coal combustion,and their contributions varied with the particles sizes.The vehicle exhaust mainly contributed to 2.1-10.2 μm particles,and coal combustion was the main source of PAHs for the particles of 1.3-2.1 μm or smaller than 1.3 μm.The contribution rates were 63.0%,56.8% and 58.7%,respectively.