| Carbonaceous aerosol is one of the most important components of atmospheric aerosols, the main components of organic carbon (OC) and elemental carbon (EC), accounted for more than 95% of carbonaceous aerosols, which play an important role on the global climate, air quality and human health. Because OC and EC have many forms of existence, their chemical properties and optical properties are obviously different. The accurate determination of OC and EC in the atmosphere is the key and difficult point in the study of atmospheric environment. In recent years, the frequent outbreak of haze in Beijing, is mainly due to the internal and external cause and the results of the superposition. This paper compares the different carbonaceous aerosol monitoring method, to determine the optimum monitoring scheme. By using continuous observation of carbonaceous aerosol data, a comprehensive analysis of the influence of seasonal variation characteristics, diurnal variation, meteorological factors, motor vehicle emissions and biomass burning is conducted. Finally, through the heavy haze in winter of Beijing’s case analysis, clear weather situation and meteorological conditions on the haze formation as an important role.The results show that:(1) Measurement method:Among three kinds of temperature protocol of online OCEC analyzer, R method is of the best in R method, F method and N method. The results of TC, OC and EC measurement by the off-line analysis of the filter sample and online analysis are different, but there is a significant linear correlation between them. (2) Concentration characteristic:The concentration of OC and EC in the atmosphere of Beijing is in the middle level of the whole country. The OC concentration is the lowest in summer and the highest in winter, while EC concentration is highest in autumn and lowest in summer. The diurnal changes of OC show bimodal obviously, and the peak value of EC is in the night. The concentration of SOC was highest in winter and lowest in summer. Winter and autumn concentration of SOC is about 1.7 times in spring and summer. The average vehicle emission OC is 4.1+1.2μg/m3, accounting for 25.8 persent of the total OC concentration of Beijing, but there was no significant change in OCvehicle/OC in a year. Biomass emission of OC is high for May, June, Novemer and lowest in summer. OCBiomass buring in June is highest for 3.17μg/m3, accounted for 28.5% of the total concentration of OC. While OCBiomass buring is the lowest in August for 1.06μg/m3, only accounted for 6.6% of OC. OCBiomass buring in November is the second high value of 2.5μg/m3, accounted for 13.0% of OC concentrations. (3) Meteorological causes: when the ground circulation system in Beijing area is by the control of low or weak high pressure, heavy haze pollution is easy to produce, especially under the uniform pressure fieled of the control, easy to form the continuous pollution. When under southwest airflow or southeast wind, due to high humidity air transportation, Beijing is easy to form long time continuous pollution, and a deeper level of pollution. When Beijing is in high pressure front, under the influence of a strong north wind, pollutants can be diluted as soon as possible. The pollutant concentration is relatively low in high speed wind and low humidity. While the low wind and high humidity will lead to the rapid growth of the pollutants. The pollutants are also in a low level under low wind and low humidity. Large range of the diurnal temperature lead to strong radiation inversion, which is conducive to the formation of a stable boundary layer and is positive to the formation of pollution. |
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