| Organic aerosol（OA）is an important part of atmospheric PM2.5 and its composition is complex.It can not only directly affect air quality and climate change,but also directly damage human health.Located in East China,Qingdao is an important national port city and tourist center.However,due to the strong urban construction activities and the rapid development of industrial enterprises,Qingdao has an atmospheric PM2.5 Pollution has increased.Although air pollution in Qingdao has been effectively controlled,there is still an urgent need to reduce PM2.5.Besides,research on organic aerosol pollution in Qingdao is relatively lacking.This study set a sampling site which can represent the environment of Qingdao city and collected samples of PM2.5.The concentration of carbon components（OC,EC）is analyzed by photothermal analysis.The organic aerosol components were analyzed by gas chromatography-mass spectrometry（GC-MS）.The concentration of secondary organic carbon（SOC）is calculated by the OC/EC minimum ratio method.This study also analyzed the concentration characteristics of various organic compounds in different seasons and different pollution situations.Source analysis methods include eigen-ratio method,principal component analysis（PCA）,positive matrix factor analysis model（PMF）and concentration weighted trajectory analysis（CWT）with HYSPLIT model to determine the source of organic aerosols in order to analyze the contribution value of each source category and the pair of atmospheric air masses.It also can provide data support for organic aerosol source analysis and the control of atmospheric particulate matter pollution.In this study,the mass concentrations of PM2.5 in Qingdao during the winter,spring and autumn sampling periods were（91.4±53.4）,（30.9±16.8）and（26.9±14.6）μg/m3,respectively.Among them,the concentration of carbon components were different significantly in different seasons.The concentrations of OC in each sampling season were（12.1±4.6）,（5.7±2.4）and（4.3±1.5）μg/m3.The concentrations of EC were（3.4±1.5）,（1.7±0.9）and（0.7±0.4）μg/m3.The concentrations of secondary organic carbon（SOC）in each sampling period were（3.2±1.6）,（2.3±1.5）and（2.1±1.2）μg/m3.The average values of the OC/EC ratios in each sampling season were 3.7,3.6and 6.1,respectively,indicating the SOC made an important contribution to OC in Qingdao8 types of organic molecular compounds were quantitatively analyzed in PM2.5samples.The total average concentrations of organic aerosols measured during the sampling period in each season were（1205.5±640.1）,（878±443.9）and（865.7±298.4）ng/m3.Among all of the species,the concentration of n-alkanes,organic acids,sugars and polycyclic aromatic hydrocarbons is significantly higher than that of other species.In this study,the PCA and PMF models identified similar sources.The PMF model analysis results showed that the main sources of machine aerosols in Qingdao were coal combustion（25.9%）,secondary conversion（19.2%）,biomass combustion（17.5%）,motor vehicles（16.0%）,higher vegetable waxes（11.6%）,cooking（8.5%）and marine aerosols（1.4%）.The contribution of coal and biomass in winter were higher（33.9%and 21.3%,respectively）.The contribution of SOA,higher vegetable wax and marine aerosol were the lowest in the all seasons.Coal combustion was the highest contribution in spring.Besides,the contribution of higher vegetable waxes and SOA increased significantly.In autumn,the contribution of SOA was the highest,followed by coal combustion,motor vehicles and biomass combustion.The contribution of higher vegetable waxes was higher than that of spring and winter.The results of concentration weight trajectory analysis showed that the distribution of potential sources in winter was mainly concentrated in parts of Shandong Province,while the regional transmission is more serious in spring and autumn.The potential sources of various pollution tracers were mainly distributed in Shandong Province（Qingdao and the surrounding cities of it）,Hebei Province,Jiangsu Province,Liaoning Province and Inner Mongolia and other regions. |
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