John N. Crowley, Raphael Dörich, Philipp Eger, Frank Helleis, Ivan Tadic, Horst Fischer, Jonathan Williams, Achim Edtbauer, Nijing Wang, Bruna A. Holanda, Mira Poehlker, Ulrich Pöschl, Andrea Pozzer and Jos Lelieveld
{"title":"CAFE-Africa期间非洲西部大西洋上空的过氧乙酰型一氧化氮酸酐(PAN)和过氧乙酸(PAA)及生物质燃烧的影响","authors":"John N. Crowley, Raphael Dörich, Philipp Eger, Frank Helleis, Ivan Tadic, Horst Fischer, Jonathan Williams, Achim Edtbauer, Nijing Wang, Bruna A. Holanda, Mira Poehlker, Ulrich Pöschl, Andrea Pozzer and Jos Lelieveld","doi":"10.1039/D5EA00006H","DOIUrl":null,"url":null,"abstract":"<p >PAN (CH<small><sub>3</sub></small>C(O)O<small><sub>2</sub></small>NO<small><sub>2</sub></small>) is often the most important chemical reservoir of reactive nitrogen compounds throughout the free- and upper troposphere and provides a means of transport of reactive nitrogen from source regions to more remote locations. Both PAN and PAA (peroxy acetic acid, CH<small><sub>3</sub></small>C(O)OOH) are formed exclusively <em>via</em> reactions of the CH<small><sub>3</sub></small>C(O)O<small><sub>2</sub></small> radical, with PAA favoured under low NO<small><sub><em>X</em></sub></small> conditions. We present airborne measurements of PAN and PAA taken with a chemical-ionisation mass spectrometer on board the High Altitude-Long range (HALO) aircraft over the North and tropical Atlantic Ocean west of Africa in August–September 2018. Our observations showed that mixing ratios of PAN and PAA are enhanced in biomass-burning impacted air masses and we determined molar enhancement ratios for both trace gases relative to CO and CH<small><sub>3</sub></small>CN. The PAA-to-PAN ratio was enhanced in biomass-burning impacted air masses compared to background air, which may reflect the continued photochemical formation of PAA in such plumes even after NO<small><sub><em>X</em></sub></small> has been largely depleted. This was confirmed by the large ratio of PAN/(PAN + NO<small><sub><em>X</em></sub></small>), which was on average ≈0.8 at 7–8 km altitude and approached unity in biomass burning impacted air masses. Although no measurements of total reactive nitrogen species (NO<small><sub><em>y</em></sub></small>) or HNO<small><sub>3</sub></small> were available, a major fraction of NO<small><sub><em>X</em></sub></small> was likely sequestered in the form of PAN in this region, especially in air masses that had been impacted by biomass burning.</p>","PeriodicalId":72942,"journal":{"name":"Environmental science: atmospheres","volume":" 5","pages":" 620-635"},"PeriodicalIF":2.8000,"publicationDate":"2025-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2025/ea/d5ea00006h?page=search","citationCount":"0","resultStr":"{\"title\":\"Peroxy acetyl nitric anhydride (PAN) and peroxy acetic acid (PAA) over the Atlantic west of Africa during CAFE-Africa and the influence of biomass-burning†\",\"authors\":\"John N. 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We present airborne measurements of PAN and PAA taken with a chemical-ionisation mass spectrometer on board the High Altitude-Long range (HALO) aircraft over the North and tropical Atlantic Ocean west of Africa in August–September 2018. Our observations showed that mixing ratios of PAN and PAA are enhanced in biomass-burning impacted air masses and we determined molar enhancement ratios for both trace gases relative to CO and CH<small><sub>3</sub></small>CN. The PAA-to-PAN ratio was enhanced in biomass-burning impacted air masses compared to background air, which may reflect the continued photochemical formation of PAA in such plumes even after NO<small><sub><em>X</em></sub></small> has been largely depleted. This was confirmed by the large ratio of PAN/(PAN + NO<small><sub><em>X</em></sub></small>), which was on average ≈0.8 at 7–8 km altitude and approached unity in biomass burning impacted air masses. 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引用次数: 0
摘要
PAN (CH3C(O)O2NO2)通常是整个自由对流层和对流层上层最重要的活性氮化合物化学储存库,并提供活性氮从源区运输到更偏远地区的手段。PAN和PAA(过氧乙酸,CH3C(O)OOH)均由CH3C(O)O2自由基反应生成,其中PAA在低NOX条件下更有利。本文介绍了2018年8月至9月在非洲西部的北大西洋和热带大西洋上空,高空远程(HALO)飞机上使用化学电离质谱仪对PAN和PAA进行的机载测量。我们的观察表明,PAN和PAA的混合比例在生物质燃烧影响的空气团中得到增强,我们确定了两种微量气体相对于CO和CH3CN的摩尔增强比。与背景空气相比,受生物质燃烧影响的气团中PAA与pan的比值增加,这可能反映了即使在NOX大部分耗尽后,这些气团中PAA的光化学形成仍在继续。PAN/(PAN + NOX)比值较大,在7 ~ 8 km高度平均≈0.8,且在生物质燃烧影响气团中趋于一致。虽然没有总活性氮(NOy)或HNO3的测量数据,但该地区大部分NOX可能以PAN的形式被封存,特别是在受到生物质燃烧影响的气团中。
Peroxy acetyl nitric anhydride (PAN) and peroxy acetic acid (PAA) over the Atlantic west of Africa during CAFE-Africa and the influence of biomass-burning†
PAN (CH3C(O)O2NO2) is often the most important chemical reservoir of reactive nitrogen compounds throughout the free- and upper troposphere and provides a means of transport of reactive nitrogen from source regions to more remote locations. Both PAN and PAA (peroxy acetic acid, CH3C(O)OOH) are formed exclusively via reactions of the CH3C(O)O2 radical, with PAA favoured under low NOX conditions. We present airborne measurements of PAN and PAA taken with a chemical-ionisation mass spectrometer on board the High Altitude-Long range (HALO) aircraft over the North and tropical Atlantic Ocean west of Africa in August–September 2018. Our observations showed that mixing ratios of PAN and PAA are enhanced in biomass-burning impacted air masses and we determined molar enhancement ratios for both trace gases relative to CO and CH3CN. The PAA-to-PAN ratio was enhanced in biomass-burning impacted air masses compared to background air, which may reflect the continued photochemical formation of PAA in such plumes even after NOX has been largely depleted. This was confirmed by the large ratio of PAN/(PAN + NOX), which was on average ≈0.8 at 7–8 km altitude and approached unity in biomass burning impacted air masses. Although no measurements of total reactive nitrogen species (NOy) or HNO3 were available, a major fraction of NOX was likely sequestered in the form of PAN in this region, especially in air masses that had been impacted by biomass burning.