High- and low-temperature pyrolysis profiles describe volatile organic compound emissions from western US wildfire fuels
High- and low-temperature pyrolysis profiles describe volatile organic compound emissions from western US wildfire fuels
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DOI：
10.5194/acp-18-9263-2018
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发表时间：
2018-07
影响因子：
6.3
通讯作者：
K. Sekimoto;A. Koss;J. Gilman;Vanessa Selimovic;M. Coggon;K. Zarzana;Bin Yuan;B. Lerner;S. Brown;C. Warneke;R. Yokelson;J. Roberts;J. D. de Gouw
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作者：
K. Sekimoto;A. Koss;J. Gilman;Vanessa Selimovic;M. Coggon;K. Zarzana;Bin Yuan;B. Lerner;S. Brown;C. Warneke;R. Yokelson;J. Roberts;J. D. de Gouw
抽象的。生物质燃烧是挥发性有机化合物（VOC）和许多其他痕量物质进入大气的主要来源，这些物质可作为臭氧和细颗粒物等二次污染物的前体。在FIREX 2016实验室密集期间使用质子转移反应飞行时间质谱仪进行的测量使用正矩阵因子分解（PMF）进行分析，以了解生物质燃烧VOC排放的瞬时变化，并简化这些类型排放的描述。尽管排放的复杂性和可变性，我们发现，仅包括两个排放曲线的解决方案，这是排放的VOC的相对丰度的质谱表示，平均解释了美国西部代表性的各种燃料（包括各种针叶树和查帕拉尔燃料）的VOC排放的85%。此外，几乎所有测试的燃料类型的曲线都非常相似。例如，美国黄松（针叶树）和曼萨尼塔（查帕拉尔）各剖面的相关系数r2均高于0.84。这两个挥发性有机化合物配置文件之间的组成差异似乎与燃料生物聚合物在高温和低温下的热解过程中的差异有关。这些热解过程被认为是VOC排放的主要来源。“高温”和“低温”热解过程并不完全对应于常用的“燃烧”和“阴燃”类别，如修正燃烧效率（MCE）所述。平均大气特性（例如，OH反应性、挥发性等）的高温和低温曲线有显著不同。我们还发现，这两个VOC配置文件可以描述以前报告的VOC数据的实验室和现场烧伤。
Abstract. Biomass burning is a large source of volatile organic compounds (VOCs) and many other trace species to the atmosphere, which can act as precursors to secondary pollutants such as ozone and fine particles. Measurements performed with a proton-transfer-reaction time-of-flight mass spectrometer during the FIREX 2016 laboratory intensive were analyzed with positive matrix factorization (PMF), in order to understand the instantaneous variability in VOC emissions from biomass burning, and to simplify the description of these types of emissions. Despite the complexity and variability of emissions, we found that a solution including just two emission profiles, which are mass spectral representations of the relative abundances of emitted VOCs, explained on average 85 % of the VOC emissions across various fuels representative of the western US (including various coniferous and chaparral fuels). In addition, the profiles were remarkably similar across almost all of the fuel types tested. For example, the correlation coefficient r2 of each profile between ponderosa pine (coniferous tree) and manzanita (chaparral) is higher than 0.84. The compositional differences between the two VOC profiles appear to be related to differences in pyrolysis processes of fuel biopolymers at high and low temperatures. These pyrolysis processes are thought to be the main source of VOC emissions. “High-temperature” and “low-temperature” pyrolysis processes do not correspond exactly to the commonly used “flaming” and “smoldering” categories as described by modified combustion efficiency (MCE). The average atmospheric properties (e.g., OH reactivity, volatility, etc) of the high- and low-temperature profiles are significantly different. We also found that the two VOC profiles can describe previously reported VOC data for laboratory and field burns.