深圳近地层大气日间VOCs垂直分布特征观测研究  

Vertical distribution of day-time volatile organic compounds in the near-surface atmosphere in Shenzhen

作　　者：崔卓彦 邱志诚 孙天乐 程勇 王碧璇 黄晓锋 何凌燕 CUI Zhuoyan;QIU Zhicheng;SUN Tianle;CHENG Yong;WANG Bixuan;HUANG Xiaofeng;HE Lingyan(Laboratory of Atmospheric Observation Supersite,School of Environment and Energy,Peking University Shenzhen Graduate School,Shenzhen 518055;Shenzhen Environmental Monitoring Center of Guangdong Province,Shenzhen 518049)

机构地区：[1]北京大学深圳研究生院环境与能源学院大气观测超级站实验室,深圳518055 [2]广东省深圳生态环境监测中心站,深圳518049

出　　处：《环境科学学报》2023年第8期226-234,共9页Acta Scientiae Circumstantiae

基　　金：深圳市科技计划(No.GXWD20201231165807007-20200808165742001)。

摘　　要：为探究近地层大气日间VOCs(挥发性有机物)垂直分布特征以及对臭氧(O3)生成的影响,2021年9月,在深圳市气象梯度塔的11个垂直梯度上开展了6轮VOCs离线罐采样,并应用气相色谱质谱联用仪对102种组分进行定量分析.结果表明,从地面(0 m)到高空(345 m)VOCs总体污染水平相近,近地层大气垂直混合较为均匀;但烯烃浓度随高度增加下降明显,主要受人为源排放的乙烯变化主导;高反应性的OVOCs(含氧挥发性有机物)在较高垂直梯度上(240~345 m)增长明显,可能是导致O3在高空浓度显著大于地面的原因之一.各垂直梯度上的臭氧生成潜势(OFP)占比排序均为:OVOCs>芳香烃>烷烃>烯烃>卤代烃>炔烃,乙酸乙酯、乙醛和甲苯是促进O3生成的优势物种.日变化方面,大多数情况下不同高度的总挥发性有机物(TVOCs)浓度均在9:00最高,推测主要受早高峰时段交通尾气排放影响;随着光化学反应的进行,OVOCs浓度在13:00达到最大,推动O3浓度于午间达到峰值.X/E(间,对-二甲苯/乙苯)比值分析也表明,气团在210 m以上高空呈现更明显的老化趋势,增加了OVOCs占比,并进一步促进高空的光化学反应.In order to explore the vertical distribution of volatile organic compounds(VOCs)in the near-ground atmosphere and their impact on O3 formation during the daytime,we collected six rounds of VOCs tank samples at 11 vertical gradients from Shenzhen Meteorological Gradient Tower in September 2021 and analyzed 102 components using a gas chromatography-mass spectrometry.The results showed that the total VOCs concentration varied little from the surface to 345 m,suggesting the near-surface atmosphere was vertically well-mixed.However,the concentration of alkenes decreased significantly with elevation,driven by the drop of anthropogenic emitting ethylene.Highly reactive oxygenated volatile organic compounds(OVOCs)increased dramatically at high attitudes(240~345 m),which may cause a higher level of O3 concentration at high altitudes than the surface.The ranking of the proportion of OFP(ozone formation potential)at each vertical gradient was:OVOCs>aromatic hydrocarbons>alkanes>alkenes>halogenated hydrocarbons>alkynes.Ethyl acetate,acetaldehyde and toluene were the dominant species that promoted ozone formation.In terms of diurnal variation,the concentration of total volatile organic compounds(TVOCs)was highest at 9 o'clock,mainly affected by traffic emission at rush hours.The concentration of OVOCs peaked at 13:00 with the photochemical reactions proceeding.Analysis of X/E(m,p-xylene/ethylbenzene)ratio also indicated a more aged air masses above 210m altitude,increasing the proportion of OVOCs and further stimulating the photochemical reactions in the upper atmosphere.

关 键 词：挥发性有机物(VOCs) 垂直分布 臭氧生成潜势(OFP) 气团老化 

分 类 号：X51[环境科学与工程—环境工程]