奥地利布鲁克大学Thomas Karl的研究团队近日取得一项新成果。经过不懈努力，他们发现了城市高浓度的氮氧化物引发了一种重要的化学物质-臭氧大量的向下通量。相关论文于2023年1月18日发表在《科学进展》杂志上。

该研究团队提出了城市地区臭氧、一氧化氮和二氧化氮的长期涡动相关测量，可以解开重要的物理和化学过程。总的来说，研究结果表明，城市环境中靠近地表的沉积臭氧通量与臭氧的化学转化产生的通量相比可以忽略不计。这是调节城市二氧化氮混合比的关键过程，导致莱顿比率被低估。因此，原来二氧化氮的排放被严重高估。

研究人员表示，氮氧化物(NO_x)在催化对流层臭氧形成中起着核心作用。二氧化氮(NO₂)最近重新成为空气污染控制措施的一个关键目标，观测证据表明，人们对高氮氧化物的环境中的臭氧的了解有限。因此，全面了解在地表高氮氧化物状态下臭氧(O₃) -一氧化氮(NO) -二氧化氮之间快速大气循环的控制机制是至关重要的，但由于相互竞争的动力效应和化学效应，仍然具有挑战性。

附：英文原文

Title: High urban NOx triggers a substantial chemical downward flux of ozone

Author: Thomas Karl, Christian Lamprecht, Martin Graus, Alexander Cede, Martin Tiefengraber, Jordi Vila-Guerau de Arellano, David Gurarie, Donald Lenschow

Issue&Volume: 2023-01-18

Abstract: Nitrogen oxides (NO_x) play a central role in catalyzing tropospheric ozone formation. Nitrogen dioxide (NO₂) has recently reemerged as a key target for air pollution control measures, and observational evidence points toward a limited understanding of ozone in high-NO_x environments. A complete understanding of the mechanisms controlling the rapid atmospheric cycling between ozone (O₃)–nitric oxide (NO)–NO₂ in high-NO_x regimes at the surface is therefore paramount but remains challenging because of competing dynamical and chemical effects. Here, we present long-term eddy covariance measurements of O₃, NO, and NO₂, over an urban area, that allow disentangling important physical and chemical processes. When generalized, our findings suggest that the depositional O₃ flux near the surface in urban environments is negligible compared to the flux caused by chemical conversion of O₃. This leads to an underestimation of the Leighton ratio and is a key process for modulating urban NO₂ mixing ratios. As a consequence, primary NO₂ emissions have been significantly overestimated.

DOI: add2365

Source: https://www.science.org/doi/10.1126/sciadv.add2365