Abstract Levoglucosan has been extensively used as a molecular marker of biomass burning in source-apportionment studies over the last few decades. However, recent studies suggest that the atmospheric lifetime of levoglucosan may be in the order of only 1–2 days under summertime conditions relevant to prescribed/wildfires. Implications of levoglucosan reactivity to wintertime conditions, however, remain uncertain despite significant contributions of domestic wood combustion to wintertime air quality. This study presents smog chamber experiments to investigate levoglucosan decay during photo-oxidation of wood smoke over a temperature range between −8 and 10 °C. Significant decay in particle wall-loss corrected levoglucosan is only observed around 10 °C in these experiments. Theoretical analysis shows that the apparent chemical lifetime of levoglucosan increases at lower temperatures as well as at higher organic aerosol mass concentrations as a result of smaller vapor fractions. The chemical lifetime of a molecular marker is commonly interpreted by a relationship between relative decay in particle wall-loss corrected marker concentrations versus integrated OH exposure. However, this relationship strongly depends on vapor wall-loss rates in addition to temperature, organic aerosol concentrations, and OH concentrations. Therefore, inferred lifetimes from a small set of experiments from a single chamber cannot easily be generalized for the full range of atmospheric smoke conditions.

中文翻译：

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木烟烟雾室实验中左旋葡聚糖衰变的研究：气溶胶载荷、温度和蒸汽壁损失在解释结果中的重要性

摘要 在过去的几十年里，左旋葡聚糖在来源解析研究中被广泛用作生物质燃烧的分子标记。然而，最近的研究表明，在与规定/野火相关的夏季条件下，左旋葡聚糖在大气中的寿命可能只有 1-2 天。然而，尽管国内木材燃烧对冬季空气质量有重大贡献，但左旋葡聚糖对冬季条件的反应仍不确定。本研究提出了烟雾室实验，以研究在 -8 到 10 °C 的温度范围内木烟光氧化过程中左旋葡聚糖的衰变。在这些实验中，仅在 10 °C 左右观察到颗粒壁损失校正左旋葡聚糖的显着衰减。理论分析表明，左旋葡聚糖的表观化学寿命在较低温度下以及在较高有机气溶胶质量浓度下由于较小的蒸气分数而增加。分子标记物的化学寿命通常通过粒子壁损失校正标记物浓度的相对衰减与综合 OH 暴露之间的关系来解释。然而，除了温度、有机气溶胶浓度和 OH 浓度之外，这种关系很大程度上取决于蒸汽壁损失率。因此，从单个腔室的一小组实验中推断出的寿命不容易推广到整个大气烟雾条件。分子标记物的化学寿命通常通过粒子壁损失校正标记物浓度的相对衰减与综合 OH 暴露之间的关系来解释。然而，除了温度、有机气溶胶浓度和 OH 浓度之外，这种关系很大程度上取决于蒸汽壁损失率。因此，从单个腔室的一小组实验中推断出的寿命不容易推广到整个大气烟雾条件。分子标记物的化学寿命通常通过粒子壁损失校正标记物浓度的相对衰减与综合 OH 暴露之间的关系来解释。然而，除了温度、有机气溶胶浓度和 OH 浓度之外，这种关系很大程度上取决于蒸汽壁损失率。因此，从单个腔室的一小组实验中推断出的寿命不容易推广到整个大气烟雾条件。