Pollution Characteristics And Source Analysis Of Atmospheric Carbonyl Compounds In The Typical Cities Of The Yangtze River Delta

Carbonyl compounds are important intermediates in the process of atmospheric photochemical reaction.They are both important components of photochemical smog and important precursors of photochemical smog.With the continuous development of the Yangtze River Delta region,the environmental problems represented by ozone and PM2.5 are prominent,which seriously affect the people’s quality of life.Atmospheric carbonyl compounds as an important precursor of urban photochemical pollution,studying its pollution characteristics and sources,helps to understand the overall oxidation of the atmosphere,and has important significance for effective pollution control measures.Because of the complex sources of carbonyl compounds in the atmosphere,some previous studies did not accurately quantify the source of carbonyl compounds.This paper carried out off-line sampling of atmospheric carbonyl compounds and other VOC.s species at 3 sites in Nanjing,Jiangsu province in March 2017 and 6 sites in Shanghai from 2016 to 2017.VOCs online continuous observation was carried out in Shanghai from May 2017 to June.The concentration level,chemical composition,chemical activity and source of atmospheric carbonyl compounds are discussed in this paper.The main contents of this paper are as follows:(1)The average concentration of atmospheric carbonyl compounds at 3 sites in Nanjing was 5.84±1.21ppbv.Carbonyl compounds accounted for 13.9%of the total VOCs concentration.The average concentration of carbonyl compounds in Shanghai online continuous observation was 8.19±3.90ppbv,accounting for 30.7%of the total VOCs concentration.The average concentration of carbonyl compounds in the 6 sites in Shanghai was 14.44 ± 6.23ppbv,accounting for 26.9%of the total VOCs concentration.Formaldehyde,Acetaldehyde and Acetone were the most important carbonyl compounds.(2)In the 3 sites of Nanjing,the contribution of carbonyl compounds to OFP and OH reactivity accounted for 31.3%and 28.2%of the total VOCs contribution respectively.In Shanghai online continuous observation,the contribution of carbonyl compounds to OFP and OH reactivity accounted for 33.3%and 34.6%of the total VOCs contribution respectively.In the 6 sites of Shanghai,the contribution of carbonyl compounds to OFP and OH reactivity accounted for 30.3%and 40.5%of the total VOCs contribution respectively.(3)In this paper,different methods were used to analysis the sources of carbonyl compounds in Nanjing and Shanghai.Such as the species contrast value method,the source tracer ratio method,the parameterization method based on photochemical age and PMF receptor model method.The results showed that the secondary formation was an important source of carbonyl compounds in the atmosphere.In addition,vehicle exhaust,oil and gas volatilization,industrial emission,solvent and painting usage were the main sources of primary anthropogenic carbonyl compounds in the atmosphere.