Atmospheric formaldehyde, glyoxal and their relations to ozone pollution under low- and high-NOx regimes in summertime Shanghai, China
Atmospheric formaldehyde, glyoxal and their relations to ozone pollution under low- and high-NOx regimes in summertime Shanghai, China
复制标题
上海夏季低、高NOx条件下大气甲醛、乙二醛及其与臭氧污染的关系
DOI：
10.1016/j.atmosres.2021.105635
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发表时间：
2021-04-28
影响因子：
5.5
通讯作者：
Zhou, Bin
中科院分区：
文献类型：
--
作者：
Guo, Yanlin;Wang, Shanshan;Zhou, Bin
随着对夏季大气光化学污染的关注度日益增加，臭氧污染的诊断和防治受到了密切关注。甲醛（HCHO）和乙二醛（CHOCHO）都是挥发性有机化合物（VOCs）普遍存在的氧化中间体。乙二醛与甲醛的比值（RGF）被用作挥发性有机化合物排放源的一个度量指标。在本研究中，2018年夏季在上海市区采用主动差分吸收光谱（DOAS）法测量了甲醛和乙二醛的混合比以及其他痕量气体。甲醛和乙二醛的平均浓度分别为3.31±1.43 ppbv和0.164±0.073 ppbv。甲醛、乙二醛与臭氧浓度相似的日变化模式以及高度相关性表明，白天的光化学过程是这些痕量气体的主要形成途径。我们发现，随着氮氧化物（NOx）浓度的增加，相对于乙二醛，甲醛显示出更高的臭氧生成潜势。RGF比值随温度升高而增加，随二氧化氮（NO₂）浓度降低而降低。通过研究乙炔、甲苯和异戊二烯等典型挥发性有机化合物种类与甲醛和乙二醛的耦合关系，发现RGF受到环境挥发性有机化合物分布的强烈影响，这表明在将其与特定的挥发性有机化合物前体来源联系起来时应谨慎使用RGF。最后，还讨论了RGF随臭氧污染事件和天气过程的变化。
With the increasing concerns on summertime atmospheric photochemical pollution, the diagnosis and prevention of ozone pollution have been paid close attention. Both formaldehyde (HCHO) and glyoxal (CHOCHO) are ubiquitous oxidation intermediates of volatile organic compounds (VOCs). The ratio of glyoxal to formaldehyde (RGF) is used as a metric for VOCs emission sources. In this study, the mixing ratios of HCHO and CHOCHO have been measured by the active differential optical absorption spectroscopy (DOAS) method in the urban area of Shanghai during summertime in 2018, as well as other trace gases. The average levels of HCHO and CHOCHO are 3.31 +/- 1.43 ppbv and 0.164 +/- 0.073 ppbv, respectively. The similar diurnal patterns and high correlation between HCHO, CHOCHO and ozone levels implied that daytime photochemical processes are the dominant formation pathway for these trace gases. We find that with increased NOx levels, HCHO shows higher ozone formation potential relative to glyoxal. The RGF ratio increases with temperature and decreases with NO2 levels. By investigating the coupling of typical VOCs species such as acetylene, toluene and isoprene with HCHO and CHOCHO, RGF is found to be strongly impacted by the ambient VOCs profiles, suggesting that RGF should be used with caution when linking it to a given VOC precursor source. Finally, the RGF variations with ozone pollution episodes and weather processes are also discussed.