Characterization of primary and secondary wood combustion products generated under different burner loads
Characterization of primary and secondary wood combustion products generated under different burner loads
复制标题
DOI：
10.5194/acp-15-2825-2015
复制
发表时间：
2015-01-01
影响因子：
6.3
通讯作者：
Prevot, A. S. H.
中科院分区：
文献类型：
--
作者：
Bruns, E. A.;Krapf, M.;Prevot, A. S. H.
居民燃烧木材对大气总气溶胶负荷有贡献；然而，木材燃烧产品的大小和特性仍然存在很大的不确定性。一次排放受各种参数的影响，包括用具类型、燃烧器木材负荷和木材类型。除了直接排放的颗粒外，以前的实验室研究表明，气相排放的氧化产生的化合物具有足够低的挥发性，很容易分配到颗粒中，形成相当数量的二次有机气溶胶(SOA)。然而，人们对木材燃烧的二氧化硫知之甚少，燃烧参数对二氧化硫的形成和组成的影响还有待确定。显然有必要对木材一次燃烧和二次燃烧气溶胶进行进一步的研究，以促进我们对大气气溶胶及其对健康、空气质量和气候的影响的了解。首次通过烟雾室内实验来研究木材负荷对一次和二次木材燃烧产物的影响。使用包括气溶胶质谱仪(AMS)在内的一系列颗粒和气相仪器对产品进行了表征。开发了一种从AMS数据定量多环芳烃(PAH)的新方法，并将结果与过滤样品的GC-MS分析结果进行了比较。在高和平均木材负载下，观察到相似的总颗粒物质量排放因子；但是，与平均负载相比，高燃料负载产生的多环芳烃对总有机气溶胶(OA)质量的贡献明显更高。在高负荷实验中，多环芳烃对总OA质量的贡献率为15+/-4%(平均+/-2样本标准差)，而在平均负荷实验中为4+/-1%。随着年龄的增长，高负荷实验的总OA浓度增加了3+/-1倍，而平均负荷实验为1.6+/-0.4倍。在AMS中，随着老化，较低m/z值的多环芳烃和芳香族特征离子增加，可能是较大的官能化多环芳烃的碎片。过滤样品还显示，随着老化，颗粒物中官能化的多环芳烃含量增加，特别是氧化的萘物种。由于多环芳烃及其氧化产物已知对健康有害，这是一个值得注意的发现，通过改进燃烧器操作规程，有助于减轻木头燃烧的负面影响。
Residential wood burning contributes to the total atmospheric aerosol burden; however, large uncertainties remain in the magnitude and characteristics of wood burning products. Primary emissions are influenced by a variety of parameters, including appliance type, burner wood load and wood type. In addition to directly emitted particles, previous laboratory studies have shown that oxidation of gas-phase emissions produces compounds with sufficiently low volatility to readily partition to the particles, forming considerable quantities of secondary organic aerosol (SOA). However, relatively little is known about wood burning SOA, and the effects of burn parameters on SOA formation and composition are yet to be determined. There is clearly a need for further study of primary and secondary wood combustion aerosols to advance our knowledge of atmospheric aerosols and their impacts on health, air quality and climate.For the first time, smog chamber experiments were conducted to investigate the effects of wood loading on both primary and secondary wood combustion products. Products were characterized using a range of particle-and gas-phase instrumentation, including an aerosol mass spectrometer (AMS). A novel approach for polycyclic aromatic hydrocarbon (PAH) quantification from AMS data was developed and results were compared to those from GC-MS analysis of filter samples.Similar total particle mass emission factors were observed under high and average wood loadings; however, high fuel loadings were found to generate significantly higher contributions of PAHs to the total organic aerosol (OA) mass compared to average loadings. PAHs contributed 15 +/- 4% (mean +/- 2 sample standard deviations) to the total OA mass in high-load experiments, compared to 4 +/- 1% in average-load experiments. With aging, total OA concentrations increased by a factor of 3 +/- 1 for high load experiments compared to 1.6 +/- 0.4 for average-load experiments. In the AMS, an increase in PAH and aromatic signature ions at lower m/z values, likely fragments from larger functionalized PAHs, was observed with aging. Filter samples also showed an increase in functionalized PAHs in the particles with aging, particularly oxidized naphthalene species. As PAHs and their oxidation products are known to have deleterious effects on health, this is a noteworthy finding to aid in the mitigation of negative wood burning impacts by improving burner operation protocols.