西安市主城区冬夏季大气挥发性有机物污染特征及来源研究

Characteristics and Source Analysis of Atmospheric VOC s Pollution in Main Urban Area of Xi an During Winter and Summer

为探究西安市主城区大气挥发性有机物(VOC s)冬夏季变化特征,于冬季(2019.12.1-2020.2.29)和夏季(2020.6.4-8.29)进行了VOC s观测,分析其浓度水平、组分及二次生成潜势,利用正交矩阵因子分解法(PMF)解析其来源。结果表明,西安市主城区冬夏季VOC s平均浓度分别为(174.79±58.06)μg/m^(3)和(138.15±35.55)μg/m^(3),含氧有机物占比最大,前10关键组分累计占总VOC s的49.10%和62.26%;夏季臭氧生成潜势(OFP)高于冬季,含氧有机物占主导;SOA生成潜势以苯系物(BTEX)为主要贡献物;PMF来源分析显示冬季以化石燃烧源为主,夏季以油气挥发为主,两季中机动车尾气、溶剂使用等常规来源较稳定。

In order to explore the variation characteristics of atmospheric volatile organic compounds(VOC s)in the main urban area of Xi an during winter and summer,the ambient concentration of VOC s were monitored from December 1th,2019 to February 29th,2020(winter)and from June 4th to August 29th,2020(summer).The concentration level,composition,secondary generation potential and source of VOC s were analyzed.Result showed that the average concentrations of VOC s were(174.79±58.06)μg/m^(3)and(138.15±35.55)μg/m^(3)during winter and summer,OVOC s were the main compounds.The top 10 species cumulatively accounted for 49.1%and 62.26%of total VOC s during winter and summer.The ozone formation potential(OFP)in summer was slightly higher than winter,and OFP of oxygenated compounds was the highest both during winter and summer.Benzene series were the main contributor to the secondary organic aerosol(SOA)potential both in winter and summer.There were differences in the sources of VOC s during winter and summer by using the positive matrix factorization model(PMF).The main sources were fossil burning in winter and gasoline evaporation in summer.Conventional sources such as motor vehicle exhaust and solvent using were relatively stable.