Comprehensive Analysis Of Sources And Characteristics Of Atmospheric Volatile Organic Pollutants In Ningbo City

Volatile organic compounds(VOCs)are main gas precursors of photochemical smog.Production of urban ozone is a chemical process controlled by VOCs,and high organic matter content in fine particles is related to VOCs production.VOCs in the air have been a type of important pollutants in urban area.Research on sources and characteristics of VOCs is a key step to control urban photochemical pollution.It studied important industrial parks closing to the ocean in Ningbo City,including Zhenhai District,Beilun District,Xiangshan Country,Cixi Country and downtown of Ningbo.VOCs samples in four seasons of spring,summer,fall and winter were collected,then time and space distribution law of VOCs concentration and chemical comsposition in the important industrial parks were obtained.Based on the above data,receptor models were used to analyze VOCs sources and contribution ratios of discharging sources were gained.It has been found that average VOCs in key areas is ranged from 35 ppb to 66 ppb.The highest concentration(65.42ppb)occurred in downtown,followed by Zhenhai(51.56ppb),Beilun(48.71ppb),Cixi(47.17ppb)and Xiangshan(35.47ppb).Compared with other cities in China,VOCs in Ningbo is in the middle and lower position.VOCs concentration in winter differs little with Beijing and cities in Pearl River Delta,and concentration in summer is much low than the cities.As for chemical composition of VOCs,in downtown,halohydrocarbon accounts for large ratio,and average chemical composition in other areas are similar,and ratios of oxygenated volatile organic compounds(OVOCs)and alkanes are the largest,followed by olefin,halogenated hydrocarbon and aromatic hydrocarbon.In fall,ratio of halogenated hydrocarbon in Ninghai is the largest,and OVOCs in Jinzhou is large.Halogenated hydrocarbon and OVOCs in different sites differ much.Based on the data,receptor models were used to analyze the source of VOCs,and it is concluded that the main sources of VOCs in Ningbo is petroleum refining and organic chemical industry,followed by motor vehicle emissions and solvent coating industry.Emission list illustrates that key industry of VOCs emission in different sites differs much.However,receptor models demonstrates that the contribution of key pollution source in each monitoring site is almost the same,which indicates that all key areas in Ningbo are polluted by petroleum refining and organic chemical industry,followed by motor vehicle emissions and solvent coating industry.Finally,the suggestions to control VOCs are put forward.