Global nitrous acid emissions and levels of regional oxidants enhanced by wildfires
Global nitrous acid emissions and levels of regional oxidants enhanced by wildfires
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DOI：
10.1038/s41561-020-0637-7
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发表时间：
2020-09
影响因子：
18.3
通讯作者：
N. Theys;R. Volkamer;J.‐F. Müller;K. Zarzana;Natalie Kille;L. Clarisse;I. D. Smedt;C. Lerot;Henning Finkenzeller;F. Hendrick;T. Koenig;C. Lee;C. Knote;Huan Yu;M. V. Roozendael
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文献类型：
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作者：
N. Theys;R. Volkamer;J.‐F. Müller;K. Zarzana;Natalie Kille;L. Clarisse;I. D. Smedt;C. Lerot;Henning Finkenzeller;F. Hendrick;T. Koenig;C. Lee;C. Knote;Huan Yu;M. V. Roozendael
亚硝酸(HONO)是大气中羟基自由基的前体，控制温室气体的降解，促进光化学烟雾和臭氧的产生，并影响空气质量。尽管众所周知，生物质燃烧对全球气溶胶和活性气体排放有很大贡献，但对HONO排放的热源贡献很少受到限制，在模型中往往被省略。在这里，我们介绍了对Tropomi/Sentinel-5先驱卫星探测仪观测的全球调查，并显示在新鲜的野火羽流中HONO排放持续增加。通过对主要生态系统(稀树草原、草原、灌丛、热带和温带森林)的比较发现，不同的生物群类型对HONO/NO2的增加比例存在系统差异，稀树草原和草原的增加比例最低，温带常绿森林的增加比例最高。在空中测量的支持下，我们证明了之前的评估将所有生态系统类型的热源HONO排放量低估了2-4倍。我们估计，HONO排放是全球新鲜野火羽流中三分之二的羟基自由基产生的原因，并加速了氧化羽流化学和臭氧的产生。我们的发现表明，热源HONO排放对大气成分有重大影响，这将使区域臭氧水平增加高达7 ppbv。
Nitrous acid (HONO) is a precursor of the hydroxyl radical in the atmosphere, which controls the degradation of greenhouse gases, contributes to photochemical smog and ozone production, and influences air quality. Although biomass burning is known to contribute substantially to global aerosols and reactive gas emissions, pyrogenic contributions to HONO emissions are poorly constrained and often omitted in models. Here we present a global survey of TROPOMI/Sentinel-5 Precursor satellite sounder observations and show that HONO emissions are consistently enhanced in fresh wildfire plumes. Comparing major ecosystems (savanna, grassland, shrubland and tropical and extratropical forests), we found that the enhancement ratios of HONO to nitrogen dioxide varied systematically with biome type, with the lowest in savannas and grasslands and highest in extratropical evergreen forests. Supported by airborne measurements, we demonstrate that previous assessments underestimate pyrogenic HONO emissions by a factor of 2–4 across all ecosystem types. We estimate that HONO emissions are responsible for two-thirds of the hydroxyl radical production in fresh wildfire plumes worldwide and act to accelerate oxidative plume chemistry and ozone production. Our findings suggest that pyrogenic HONO emissions have a substantial impact on atmospheric composition, which enhances regional ozone levels by up to 7 ppbv.