科研之友
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摘要
For a better understanding of the formation of regional haze in the North China Plain (NCP) region, aerosol concentrations and compositions, trace gases and meteorological factors were comprehensively measured for 1 year in Jinan, a typical city in the NCP. Through comparison studies between hazy & non hazy days, and five years of changes, this paper presents the characterisation of seasonal variations and sources of carbonaceous aerosol, and their implications to haze formation in the NCP region. The contributions of carbonaceous aerosols (OC x 1.8 + EC) to PM2.5 ranged from 17.2 to 30.4% on hazy days and 20.5-29.7% on non-hazy days. The annual trends of organic carbon (OC) and elemental carbon showed obvious seasonality, with the lowest and highest concentrations in spring and winter, respectively. The ratio of secondary OC to OC on hazy days during all four seasons ranged from 43.8 to 63.4%, which was higher than that on non-hazy days. Different types of haze events are identified (e.g., combustion of coal and biomass), and the sources and formation mechanisms of carbonaceous aerosols are discussed. In winter, coal combustion and secondary formation were the main sources of carbonaceous aerosols. Biomass combustion contributed to the rapid enhancement of carbonaceous aerosols during summer and autumn. We found that the OC and secondary OC concentrations on haze-fog days during the winter of 2012-2013 in Jinan were much higher than those during the winter of 2007-2008, which was consistent with the ambient relative humidity. These results suggest that aqueous reaction played a significant role in the formation of secondary organic aerosols and contributed to regional haze formation in the NCP region.
