Analysis of reduced and oxidized nitrogen-containing organic compounds at a coastal site in summer and winter
Analysis of reduced and oxidized nitrogen-containing organic compounds at a coastal site in summer and winter
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DOI：
10.5194/acp-22-3045-2022
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发表时间：
2022-03-08
影响因子：
6.3
通讯作者：
Gentner, Drew R.
中科院分区：
文献类型：
--
作者：
Ditto, Jenna C.;Machesky, Jo;Gentner, Drew R.
含氮有机化合物，其可直接排放到大气中或可通过与普遍的活性氮物质（例如，NH3，NOx，NO3）对气候和人类健康有重要但不确定的影响。使用具有软电离和高分辨率质谱的气相色谱和液相色谱，我们在夏季（2018年长岛海峡对流层臭氧研究- LISTOS -活动期间）和冬季在长岛海峡的沿海站点对功能化有机化合物进行了分子水平的形态分析。该地区经常经历空气质量差，由于活性人为，生物和海洋衍生化合物及其化学转化产物的排放。我们观察到一系列功能化的化合物含有氧，氮，和/或硫原子从这些直接排放和化学转化，包括光化学和水相处理，这是更明显的夏季和冬季，分别。在夏季和冬季，含氮的有机气溶胶占主导地位的观测分布的功能化粒子相物种电离我们的分析技术，85%和68%的总测量离子丰度含有氮原子，分别。含氮颗粒包括还原的氮官能团（例如，胺、亚胺、唑）和常见的NO2贡献者（例如，有机硝酸盐）。在颗粒相中观察到的还原氮官能团经常与分子上其他地方的含氧基团配对，它们的普遍性通常与我们的方法检测到的氧化氮基团相媲美。补充气相测量，吸附采样器上收集和分析与一种新的液相色谱法为基础的方法，表明气相还原氮化合物可能有助于前体所观察到的含氮颗粒。总之，这项工作突出了在研究较少的美国东北部和潜在的其他地区具有类似的人为，生物和海洋来源的签名减少含氮化合物的流行。
Nitrogen-containing organic compounds, which may be directly emitted into the atmosphere or which may form via reactions with prevalent reactive nitrogen species (e.g., NH3, NOx, NO3), have important but uncertain effects on climate and human health. Using gas and liquid chromatography with soft ionization and high-resolution mass spectrometry, we performed a molecular-level speciation of functionalized organic compounds at a coastal site on the Long Island Sound in summer (during the 2018 Long Island Sound Tropospheric Ozone Study - LISTOS - campaign) and winter. This region often experiences poor air quality due to the emissions of reactive anthropogenic, biogenic, and marine-derived compounds and their chemical transformation products. We observed a range of functionalized compounds containing oxygen, nitrogen, and/or sulfur atoms resulting from these direct emissions and chemical transformations, including photochemical and aqueous-phase processing that was more pronounced in summer and winter, respectively. In both summer and winter, nitrogen-containing organic aerosols dominated the observed distribution of functionalized particle-phase species ionized by our analytical techniques, with 85 % and 68 % of total measured ion abundance containing a nitrogen atom, respectively. Nitrogen-containing particles included reduced nitrogen functional groups (e.g., amines, imines, azoles) and common NOz contributors (e.g., organonitrates). Reduced nitrogen functional groups observed in the particle phase were frequently paired with oxygen-containing groups elsewhere on the molecule, and their prevalence often rivaled that of oxidized nitrogen groups detected by our methods. Supplemental gas-phase measurements, collected on adsorptive samplers and analyzed with a novel liquid chromatography-based method, suggest that gas-phase reduced nitrogen compounds are possible contributing precursors to the observed nitrogen-containing particles. Altogether, this work highlights the prevalence of reduced nitrogen-containing compounds in the less-studied northeastern US and potentially in other regions with similar anthropogenic, biogenic, and marine source signatures.