VOCs Characteristics And Source Analysis Of The Background Stations In The Tibetan Plateau

Volatile organic compounds(VOCs)is an important trace in the troposphere,in photochemical smog pollution with the main contribution,is an important precursor for urban photochemical smog pollution,a great contribution to the formation of the acid deposition of organic acids in.The research on the development of VOCs in ambient air and indoor air is of great significance to the study of regional and global atmospheric chemistry,climate change,environmental effects and human health effects.The concentrations of volatile organic compounds were monitored from 13th September 2013 to 14th October 2013,at a national background monitoring station Menyuan site,in the Tibetan plateau.Total 38 species of VOCs were detected in this study,with 16 species of alkanes,11 species of olefins,9 species of aromatic hydrocarbons,and 2 species of halogenated hydrocarbons.Alkanes were the most abundant compound class,accounted for 58.6%of the total VOCs,followed by olefins and aromatic,accounted for 29%and 10.5%respectively,halogenated hydrocarbons accounted only for 1.7%.For most of the VOCs species,the diurnal variation of mixing ration concentrations were higher in nighttime than daytime,but isoprene,i-pentane,toluene showed the opposite trends.By calculating ozone formation potential(OFP)of various VOCs,olefins made the biggest contribution.We further analysised the sources of VOCs by the method of Principal Component Analysis(PCA)and HYSPLIT 4.0 backward trajectory,confirmed that the pollutant from south and southeast of Menyuan site have a significant effects on the increase of VOCs concentration.