Preliminary Study On The Field Measurement Of Secondary Organic Aerosol Based On Single Particle Aerosol Mass Spectrometry

Secondary organic aerosol(SOA)is an important component of atmospheric fine particulate matter(PM2.5),which is mainly produced by the oxidation of volatile organic compounds(VOCs)emitted by anthropogenic or natural sources in the atmosphere.SOA will affect the radiation balance of the atmosphere,reduce visibility,form the photochemical smogs and even affect global climate change,and cause serious harm to human health.SOA has a more complex source,generation mechanism and compositional characteristics than primary source aerosol.In this study,single particle aerosol time-of-flight mass spectrometer(SPAMS)analysis technique matched with the field measurement to explore the composition characteristics and sources of SOA in typical ambient atmosphere.The main results are as follows:(1)IEPOX-derived organosulfates were observed for the first time in the field measurement of ambient atmosphere for the first time using SPAMS in Tian-jing-shan national air background monitoring station in the Nanling Mountains,South China.Organosulfates are much easier to form at high relative humidity(> 90%)and low temperatures(<18oC).The IEPOX-derived organosulfates were found to be 49% higher during nighttime than in daytime demonstrate that the studied forest area has been impacted by anthropogenic air pollutants,as indicated by the formation of anthropogenic SOA.(2)In the on-line continuous field observation of ambient air in typical industrial area,the composition characteristics of polycyclic aromatic hydrocarbons(PAHs)in the atmosphere were investigated,and the characteristic spectra were determined.In addition,we also explored the mass spectrum characteristics of aromatics SOAs in the industrial area and found that its concentration was higher in the daytime than in the night,and its trend in the daytime was related to the concentration of O3,and the second peak appeared at night,The diurnal variation of the law showed a bimodal trend.(3)In the study of typical urban ambient atmosphere,the diurnal variation of the field measurement was explored.SOA accounted for the largest proportion in the element/organic mixed carbon(ECOC)and organic carbon particles(OC)at nighttime.The secondary organic components in the various types of particles will increase significantly with the increase of solar radiation during the day.And the concentration of SOA was significantly higher in the pollution period than in the cleaning period.