Urban flux measurements reveal a large pool of oxygenated volatile organic compound emissions.
Urban flux measurements reveal a large pool of oxygenated volatile organic compound emissions.
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DOI：
10.1073/pnas.1714715115
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发表时间：
2018-02-06
影响因子：
11.1
通讯作者：
Wohlfahrt G
中科院分区：
文献类型：
--
作者：
Karl T;Striednig M;Graus M;Hammerle A;Wohlfahrt G
非甲烷挥发性有机化合物(NMVOC)在地表-大气界面的交换是大气化学及其对气候影响的基本约束和重要边界条件。人为排放被认为约占进入北半球大气的NMVOC通量的一半，但由于缺乏适当的自上而下的限制，其预算相当不确定。在这里，我们提出了基于涡旋协方差技术的NMVOC的直接通量测量，表明典型城市排放源的贡献包括令人惊讶的很大比例的含氧NMVOC。这些结果表明，典型的城市NMVOC排放源可能比目前在空气化学和气候模式中预测的要高得多。每年大量非甲烷挥发性有机化合物(NMVOC)的流入推动了大气化学的发展。这些化合物影响臭氧的形成，导致二次有机气溶胶的产生，并对大气的氧化能力起着重要作用。由于城市排放源的多样性，人为的NMVOC预算具有很大的不确定性。在这里，我们介绍了使用新设计的质子转移反应四极界面飞行时间质谱仪对城市NMVOC涡旋协方差通量的综合观测。我们发现了一个惊人的巨大的含氧非挥发性有机化合物(OVOCs)池的排放通量，其中相当一部分是较高氧化的OVOCs，这不能用已知的快速光化学转变或当前的初级排放估计来解释。测量到的OVOC/NMVOC体积通量比比从累积的人为排放清单推断的高出两到四倍。推断这些结果将使全球人为NMVOC通量翻一番。鉴于全球城市化进程加快，我们的研究强调了重新评估人为NMVOC对大气化学、人类健康和气候系统的影响的必要性。
The exchange of nonmethane volatile organic compounds (NMVOC) at the surface–atmosphere interface is a fundamental constraint and important boundary condition for atmospheric chemistry and its effects on climate. Anthropogenic emissions are thought to account for about half of the NMVOC flux into the atmosphere of the Northern Hemisphere, yet their budget is considerably uncertain due to the scarcity of appropriate top-down constraints. Here we present direct flux measurements of NMVOCs based on the eddy covariance technique, showing that the contribution of typical urban emission sources is comprised of a surprisingly large portion of oxygenated NMVOC. These results suggest that typical urban NMVOC emission sources could be significantly higher than currently projected in air chemistry and climate models. Atmospheric chemistry is fueled by a large annual influx of nonmethane volatile organic compounds (NMVOC). These compounds influence ozone formation, lead to secondary organic aerosol production, and play a significant role for the oxidizing capacity of the atmosphere. The anthropogenic NMVOC budget is considerably uncertain due to the diversity of urban emission sources. Here, we present comprehensive observations of urban NMVOC eddy covariance fluxes using a newly designed proton-transfer-reaction quadrupole interface time-of-flight mass spectrometer. We found emission fluxes of a surprisingly large pool of oxygenated NMVOCs (OVOCs) with an appreciable fraction of higher oxidized OVOCs that cannot be explained by known fast photochemical turnaround or current primary emission estimates. Measured OVOC/NMVOC bulk flux ratios are two to four times higher than inferred from aggregated anthropogenic emission inventories. Extrapolating these results would double the global anthropogenic NMVOC flux. In view of globally accelerating urbanization, our study highlights the need to reevaluate the influence of anthropogenic NMVOC on atmospheric chemistry, human health, and the climate system.
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影响因子：
6.3
作者：
Langford, B.;Nemitz, E.;Hewitt, C. N.
通讯作者：
Hewitt, C. N.
影响因子：
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作者：
Ehlers, Christian;Klemp, Dieter;Wahner, Andreas
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作者：
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作者：
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通讯作者：
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