Research On Variations And Sources Of Atmospheric Carbonyls During The 2014 Beijing APEC

Carbonyls, which is regarded as important VOCs, is ubiquitous in atmosphere and received increasingly attention. Formaldehyde, acetaldehyde and acrolein are known as irritating substances, toxic air pollutants, carcinogens and mutagens. Carbonyls can be emitted from primary sources (e.g., industries, vehicles, fuel and biomass burning, biogenic emissions) as residues from incomplete combustion or secondary sources (e.g., photo-oxidation process of organics). Formaldehyde, acetaldehyde and acetone are the dominant carbonyls in atmosphere, while the atmospheric photochemical process and vehicle exhausts are believed to be the significant source in urban. Therefore, research on atmospheric carbonyls during the 2014 Beijing APEC, providing practical experience to build effective regional environmental protection measures.In this study, ambient carbonyls in Beijing are measured during the 2014 Beijing APEC, covering the periods during the Beijing APEC without or with stringent Air-Quality control measures that air samples were collected at four intervals each days. Formaldehyde, acetaldehyde and acetone are the most abundant carbonyls, accounted for 68.65-82.66% of total carbonyls. Carbonyls are reduced by 64.10% during the APEC with vehicles control measures, among which formaldehyde reduced by 78.61%. Variations of carbonyls in the APEC are similar to other pollutants expect for O3, while the carbonyls reach their highest and lowest concentrations in different times.Formaldehyde/acetaldehyde (C1/C2) and acetaldehyde/propionaldehyde (C2/C3) exhibites a large scale (0.95-9.41 and 5.70-15.71, respectively), particular during the APEC. The C1/C2 ratios in summer are range 0.17 to 3.56 which also indirectly suggests that formaldehyde would be accumulated in hazy days, and the large scale (1.21-9.41) change during the APEC might indicate that carbonyls are from diverse sources in different time. But, the carbonyls influenced by meteorological parameters and photochemical formation of carbonyls could not be ignored, especially for the higher wind speed which attributes to carbonyls reduced during the APEC.Variations of trace compositions in particulate sampler imply that carbonyls come from various sources (e.g., vehicles, fuel burning, coal and biomass burning) in different periods. We concludes that during the APEC with control measures, vehicle emission might account for less air pollutants, while the fossil fuel emission and coal burning play important parts in increasing air pollutants in other periods, especially after the APEC with heating.