Analysis Of Plant Volatile Organic Compounds And Research About Their Effects On Ozone Generation

Volatile organic compounds(VOCs)play an important role in the photochemical reaction of ambient air,and plant leaves release volatile organic gases into the atmosphere through stomata,namely plant-derived volatile organic compounds(BVOCs),accounting for most of them.Due to the species-specific nature of BVOCs emissions,the plant biodiversity in the city is closely related to the photochemical reactivity in the urban environment,producing secondary pollutants such as secondary organic aerosols and ozone,and affecting carbon cycle balance in the biosphere and atmosphere.Street trees can play a positive role such as beautify the environment,isolate noise,absorb dust,absorb carbon dioxide.At the same time,plant volatile organic compounds also have adverse effects on ambient air,and their release is affected by many factors such as tree species,temperature,humidity,light,and location.In this study,during the period from May 2021 to January 2022,analysis of volatile components of 14 common street trees in Hefei using adsorption-desorption and TD-GC-MS,studied they seasonal change law and diurnal law.Using Maximum Incremental Activity(MIR)factor weighting to obtain the contribution of plant-released principal components to ozone generationThe research results are as follows:The volatile organic compounds released by the 14 common street trees were all dominated by terpenes,among which monoterpenes released the largest amount.The total release amount of the 14 street trees in descending order is Metasequoia >Yulania denudata grandis > Cedar > Luan Tree > Maple Poplar > Platycladus orientalis > Camphor > Weeping Willow > Albizia japonica > Platamonia >Osmanthus fragrans > Ginkgo Biloba > Sapium sebiferum > Sapindus japonica.The volatile organic compounds released by plants have obvious tree species differences,and the seasonal and diurnal changes of volatile compounds released by different plants are different.Screened of 9 tree species with large releases of main BVOCs,which 3coniferous trees(Cedar,Platycladus orientalis,Metasequoia),2 evergreen broad-leaved trees(camphora,sweet-scented osmanthus)and 5 deciduous broad-leaved trees(Yulania denudata,Luan tree,maple poplar,and sycamore),analyzed their contribution to ozone production at different times of the day in summer.The three conifers,Cedar,Platycladus orientalis and Metasequoia contributed more to ozone generation were monoterpenes and aromatic hydrocarbons,and the two evergreen broad-leaved trees,Camphor and Osmanthus,contributed more to ozone generation are 1,4-pentadiene and monoterpenes,the five deciduous broad-leaved trees contributed more to ozone generation are isoprene,1,4-pentadiene and monoterpenes.The results of the study show that,in the monitoring of atmospheric volatile organic compounds based on ambient air samples,in addition to anthropogenic sources,the emissions from natural sources cannot be ignored.Through understanding and mastering the release rules of volatile organic compounds produced by plants,it not only provides a reference for the rational selection and configuration of green plants in urban landscape design,but also provides another dimension for the refinement of atmospheric environmental quality evaluation.