New emission factors for Australian vegetation fires measured using open-path Fourier transform infrared spectroscopy - Part 2: Australian tropical savanna fires
New emission factors for Australian vegetation fires measured using open-path Fourier transform infrared spectroscopy - Part 2: Australian tropical savanna fires
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DOI：
10.5194/acp-14-11335-2014
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发表时间：
2014-01-01
影响因子：
6.3
通讯作者：
Yates, C. P.
中科院分区：
文献类型：
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作者：
Smith, T. E. L.;Paton-Walsh, C.;Yates, C. P.
热带草原火灾约占全球每年生物质燃烧碳排放总量的40-50%。最近对不同热带稀树草原地区排放因子的比较突出表明，有必要采取区域办法来制定排放因子，并更好地评估排放因子时空变化的驱动因素。本文介绍了开放路径傅里叶变换红外（OP-FTIR）光谱场测量的结果发生在热带稀树草原的北领地，澳大利亚，在不同的植被组合，并在不同阶段的旱季。通过一个长（22-70米）的开放路径，通过这些火灾释放的地面烟雾的红外光光谱收集使用红外线灯和现场便携式FTIR系统。红外光谱用于检索烟雾中存在的14种不同气体的摩尔分数，这些测量用于计算燃烧所排放的各种气体的排放比和排放因子。只有少数以前的排放因子的措施是专门为澳大利亚的热带稀树草原，在这里，我们提出了第一次报告的甲醇，乙酸和甲酸的排放因子为这个生物群落。鉴于样本量相对较大，有可能研究得出的排放系数在生物群落内变化的潜在原因。我们发现，不同的稀树草原植被组合之间的排放因子变化很大，这种变化的大部分被反映在不同的植被类的修改后的燃烧效率（MCE）的变化。我们的结论是，一个显着的大多数微量气体的排放因子的变化可以解释的MCE，无论植被类，如所示的不同的植被类使用不同的燃烧效率的数据子集的计算的甲烷排放因子的变化。因此，为排放建模目的选择排放系数不一定需要详细的燃料类型信息，如果关于MCE的数据（例如，G.根据对21起火灾的测量，我们建议澳大利亚热带稀树草原火灾的排放因子如下（单位：克气体排放每公斤干燃料燃烧），这是我们的平均测量值：1674 +/- 56克公斤（-1）的二氧化碳; 87 +/- 33克公斤（-1）的一氧化碳; 2.1 +/- 11.2 g kg（-1）甲烷; 0.11 +/- 0.04 g kg（-1）乙炔; 0.49 +/- 0.22 g kg（-1）乙烯; 0.08 +/- 0.05 g kg（-1）乙烷; 1.57 +/- 0.44 g kg（-1）甲醛; 1.06 +/- 0.87 g kg（-1）甲醇; 1.54 +/- 0.64 g kg（-1）乙酸; 0.16 +/- 0.07 g kg（-1）甲酸; 0.53 +/- 0.31 g kg（-1）氰化氢;和0.70 +/- 0.36 g kg（-1）氨。在一篇配套论文中，类似的技术被用来测量澳大利亚温带森林火灾的排放量。
Savanna fires contribute approximately 40-50% of total global annual biomass burning carbon emissions. Recent comparisons of emission factors from different savanna regions have highlighted the need for a regional approach to emission factor development, and better assessment of the drivers of the temporal and spatial variation in emission factors. This paper describes the results of open-path Fourier transform infrared (OP-FTIR) spectroscopic field measurements at 21 fires occurring in the tropical savannas of the Northern Territory, Australia, within different vegetation assemblages and at different stages of the dry season. Spectra of infrared light passing through a long (22-70 m) open-path through ground-level smoke released from these fires were collected using an infrared lamp and a field-portable FTIR system. The IR spectra were used to retrieve the mole fractions of 14 different gases present within the smoke, and these measurements used to calculate the emission ratios and emission factors of the various gases emitted by the burning. Only a handful of previous emission factor measures are available specifically for the tropical savannas of Australia and here we present the first reported emission factors for methanol, acetic acid, and formic acid for this biome. Given the relatively large sample size, it was possible to study the potential causes of the within-biome variation of the derived emission factors. We find that the emission factors vary substantially between different savanna vegetation assemblages; with a majority of this variation being mirrored by variations in the modified combustion efficiency (MCE) of different vegetation classes. We conclude that a significant majority of the variation in the emission factor for trace gases can be explained by MCE, irrespective of vegetation class, as illustrated by variations in the calculated methane emission factor for different vegetation classes using data sub-set by different combustion efficiencies. Therefore, the selection of emission factors for emissions modelling purposes need not necessarily require detailed fuel type information, if data on MCE (e. g. from future spaceborne total column measurements) or a correlated variable were available.From measurements at 21 fires, we recommend the following emission factors for Australian tropical savanna fires (in grams of gas emitted per kilogram of dry fuel burned), which are our mean measured values: 1674 +/- 56 g kg(-1) of carbon dioxide; 87 +/- 33 g kg(-1) of carbon monoxide; 2.1 +/- 11.2 g kg(-1) of methane; 0.11 +/- 0.04 g kg(-1) of acetylene; 0.49 +/- 0.22 g kg(-1) of ethylene; 0.08 +/- 0.05 g kg(-1) of ethane; 1.57 +/- 0.44 g kg(-1) of formaldehyde; 1.06 +/- 0.87 g kg(-1) of methanol; 1.54 +/- 0.64 g kg(-1) of acetic acid; 0.16 +/- 0.07 g kg(-1) of formic acid; 0.53 +/- 0.31 g kg(-1) of hydrogen cyanide; and 0.70 +/- 0.36 g kg(-1) of ammonia. In a companion paper, similar techniques are used to characterise the emissions from Australian temperate forest fires.