摘要
挥发性有机物(VOCs)化学活性差异较大,如仅通过观测浓度开展VOCs来源解析将降低活性较强物种的贡献,不利于以缓解臭氧(O_(3))污染为目的的VOCs减排。为有效降低光化学损耗对于VOCs来源解析的影响,文章通过光化学老化方法估算湘潭市城区夏季VOCs的初始浓度,矫正光化学损耗的影响,进而利用正交矩阵因子分解模型(PMF)开展VOCs来源解析研究。研究结果表明,观测期间湘潭市城区夏季VOCs平均观测浓度为(23.90±5.79)×10^(-9)(体积浓度,下同),初始浓度为(31.28±15.17)×10^(-9)。其中烯烃变化最大,是观测浓度的4.33倍,其次是芳香烃(1.87倍)。白天光化学平均总消耗量为14.66×10^(-9),以烯烃光化学消耗量为主,占总消耗量的70.7%。初始浓度、O_(3)和气温的日变化趋势基本一致,15时达到最大值,光化学损耗量也处于最大小时值(22.69×10^(-9))。O_(3)污染日烯烃和芳香烃光化学损失大于非污染日,烯烃和芳香烃的光化学损失是臭氧生成的重要来源。湘潭市城区夏季VOCs初始浓度PMF源解析结果显示工业源的贡献占比最高,观测浓度结果显示二次转化是最高的贡献源类。
Owing to the fact that chemical activity of numerous VOCs(volatile organic compounds)differs greatly,the contributions of the more active species VOCs could be weakened in case the source apportionment of VOCs is carried out merely using the observed data of VOCs concentration,which is detrimental to the VOCs emission reduction and ozone pollu⁃tion alleviation.To effectively reduce the influence of photochemical loss on VOCs source apportionment,in this study the initial concentrations of VOCs were estimated by photochemical aging method to correct the photochemical loss of ambient VOCs species,and then the positive matrix factorization(PMF)was used to conduct source apportionment of ambient VOCs.The findings of the study suggested that the average observed concentration of ambient VOCs during the observation period was(23.90±5.79)×10^(-9),and the initial concentration was(31.28±15.17)×10^(-9);and among others,variation of olefins was most drastic,being 4.33 times greater than the observed concentration,which was followed by aromatic hydrocarbons(1.87 times).The total average photochemical consumption of VOCs in daytime was 14.66×10^(-9),the photochemical consumption of olefin was the greatest,accounting for 70.7%of the total consumption.The daily variation trend of the initial concentration of ambi⁃ent VOCs,O_(3) and temperature were basically consistent,reaching the maximum value of the initial concentration at 15:00 with the biggst hourly maximum photochemical loss value(22.69×10^(-9)).The photochemical loss of olefins and aromatics during O_(3) pollution days was greater than that during non-pollution days,and which became an important source of ozone generation.According to the results of the VOCs source apportionment of initial concentrations by use of PMF,the industrial pollution source in Xiangtan’s urban area was the most remarkable contribution source during summer,while the secondary transformation was the biggst contributor source in accordance with the observed concentrations.
作者
何立志
谢诚
肖正辉
HE Lizhi;XIE Cheng;XIAO Zhenghui(Xiangtan Ecological Environment Monitoring Center of Hunan Province,Xiangtan 411100,China;School of Earth Science and Spatial Information Engineering,Hunan University of Science and Technology,Xiangtan 411201,China)
出处
《环境科学与技术》
CAS
CSCD
北大核心
2024年第3期101-110,共10页
Environmental Science & Technology
基金
湘潭市科学技术局《湘潭市创建国家创新型城市建设专项》(SF-YB20221014)。
关键词
VOCS
初始浓度
光化学损耗
来源解析
VOCs
initial concentration
photochemical loss
source apportionment
