Analysison VOCs Offive Species Of Trees Andestimation Of Formation Of Potential Of SOA

Bio-volatile organic compounds(BVOCs)are a trace of gas in the atmosphere and are actively involved in all kinds of chemical reactions in the atmosphere.Among them,the emission of VOCs in plants will affect the atmospheric chemical process,thus affecting the air quality,so the plant VOCs composition analysis,influencing factors and environmental benefits of research is one of the hot spots in Ecology recent years.In this study,five common trees in Guan-Zhong Region in Shaanxi Province including Pinus tabulaeformis,Platycladus orientalis,Cedrus deodara,Pinus bungeana and Picea asperata were chosen as research objects.The research adopted living plants dynamic headspace method to collect VOCs in the autumn of 2016,used Thermodesorption Cold Trap-Gas Chromatography Mass Spectrometery apparatus(TCT-GC-MS)for qualitative analysis and external standard method for quantitative analysis.Based on these,the research studied dynamic changes of VOCs and correlation with environmental factors,and estimated the formation potential of secondary organic aerosol(SOA)by using fractional aerosol coefficients(FAC)to provide reference for urban greening.The main conclusions of this article are:(1)The diurnal variation of the number of organic volatiles of Pinus tabulaeformis,Platycladus orientalis,Cedrus deodara,Pinus bungeana and Picea asperata was statistically analyzed.There are 81 kinds of VOCs in leaves of P.tabuliformis.The number of alkene,alkane and alcohol was more than that of 5 species;there are 64 kinds of VOCs in leaves of Platycladus orientalis.The number of alkene,alkane and aromatic hydrocarbon is more,and the other species are less than 5;There are 61 kinds of VOCs in leaves of Cedrus deodara.The number of alkene,alkane,aromatic hydrocarbon and alcohol are more than others;There are 56 kinds of VOCs in leaves of Pinus bungeana.The number of alkene,alkane,aromatic hydrocarbon and alcohol are more than others;There are 45 kinds of VOCs in leaves of Picea asperata.The number of alkene,alkane,aromatic hydrocarbon and alcohol are more than others.(2)Alkene released by Pinus tabulaeformis occupies over 90% of TBVOCs,?-pinene,limonene,?-myrcene,?-pinenecan and ?-farnesene has high content,other kinds of VOCs were little;alkene released by Platycladus orientalis occupies about 80% of TBVOCs.?-pinene reach up to about 60% of TBVOCs.D-limonene can account for about 9% of TBVOCs.2-thujene can account for about 4% of TBVOCs.The relative content of alkanes is 10% of the total volatiles,and the higher content is cyclohexane;alkene released by Cedrus deodara occupies about 90% of TBVOCs.The relative content of ?-pinene was the highest among the five species,accounting for 60% of the total volatiles.The relative content of ?-pinene was the lowest in 5 species,only about 5%;The VOCs of Pinus bungeana and Picea asperata have a large amount of monoterpenes and sesquiterpenes,and the relative content of ketones is much larger than that of the other three species,which is about 10%.(3)Concentration of VOCs: With the influence of environmental factors,the concentration of VOCs of five kinds of arsenic showed obvious diurnal variation.With the change of temperature,humidity and solar radiation,the Concentration of VOCs of five kinds of trees showed the first increase and after reduction of single peak day change,The lowest peak appeared in the morning 8:00-9:30,The concentration of five species of trees is 148.481ug/m3,141.235ug/m3,260.447ug/m3,86.770ug/m3,125.507ug/m3;the highest peak appeared in 12:00-13:30.The concentration of five species of trees is 416.793ug/m3,325.897ug/m3,514.121ug/m3,270.143ug/m3,395.723ug/m3.(4)Volatile secondary organic aerosols: Pinus tabulaeformis organic volatiles produced SOA daily average concentration of 68.404ug/m3.Platycladus orientalis has an average concentration of 59.965 ug/m3.The average concentration of Cedrus deodara is 78.496ug/m3.The average concentration of Pinus bungeana is 56.533ug/m3.The average concentration of Picea asperata is 60.882 ug/m3,far greater than the concentration of the atmosphere outside the forest.