Pollution Characteristic and Source Analysis of Volatile Organic Compounds in Summer in Dalian
In order to explore the concentration levels,composition characteristics and potential sources of VOCs(volatile organic compounds)in Dalian,EXPEC 2000 atmospheric VOC monitoring system had been used to conduct online observations of 115 VOCs in the atmosphere at two sites in industrial area and residential area in summer 2021.The volume fractions of total volatile organic compounds(TVOCs)and species composition were analyzed and OFP(ozone formation potential)was estimated at the two sites.The sources were analyzed sequentially based on PMF(positive definite matrix factorization)model.The results showed that the mean values of VOCs volume fraction in industrial and residential areas during the observation period were 17.99×10-9 and 18.17×10-9,respectively.The mean OFP values were 109.14 μg/m3 and 99.27 μg/m3,respectively,with a significant increasing trend in the early morning from 06:00-08:00 and in the evening from 17:00-19:00,which may be related to the morning and evening peaks of motor vehicles.Industrial area OFP had a sudden high at night from 21:00-03:00.The top 10 species contributing to OFP in industrial area were m/p-xylene,isoprene,acetaldehyde,etc.and in residential area were isoprene,ethylene,propylene,etc.The PMF results showed that fossil fuel volatilization(32.8%),solvent use(31.4%),fossil fuel combustion(19.3%),and petrochemical emissions(16.6%)were the main sources of VOCs for the industrial area sites,and motor vehicle emissions(40.2%),fossil fuel volatilization(32.6%),solvent use(20.2%),and plant emissions(7.0%)for the residential area sites.Sources of solvent use(57.4%),fossil fuel volatilization(19.8%),and fossil fuel combustion(16.1%)contributed more to OFP in industrial area,and motor vehicle emissions(40.8%),fossil fuel volatilization(27.8%),and solvent use(23.9%)in residential area.The control of O3 pollution in industrial areas of Dalian can focus on solvent volatilization,fuel fugitive and combustion in the industrial production process,while the control of motor vehicle emissions and oil vaporization in residential areas is the key.
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