Presto Albert A, Hartz Kara E Huff, Donahue Neil M
Department of Chemistry and Department of Chemical Engineering, Doherty Hall, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA.
Environ Sci Technol. 2005 Sep 15;39(18):7036-45. doi: 10.1021/es050174m.
We report secondary organic aerosol (SOA) yields from the ozonolysis of alpha-pinene under both dark and UV-illuminated conditions. Exposure to UV light reduces SOA yield by 20-40%, with a maximum reduction in yield coinciding with a minimum in the amount of terpene consumed (15-30 ppb). The data are consistent with a constant absolute reduction in the yield of approximately 0.03. Gas chromatography mass spectrometry analysis of filter samples indicates that the major products found in alpha-pinene SOA include organic acids (e.g., pinic acid), keto acids (e.g., pinonic acid), and hydroxy keto acids (e.g., 10-hydroxypinonic acid). Analysis of filter-based results suggests that yield reduction is a result of the formation of a more volatile product distribution when experiments are conducted in the presence of UV light. These results implythat previous "dark bag" experiments may overestimate SOA generation from monoterpenes and also that SOA generation in the atmosphere may depend significantly on actinic flux.
我们报告了在黑暗和紫外线照射条件下α-蒎烯臭氧分解产生的二次有机气溶胶（SOA）产率。暴露于紫外线下会使SOA产率降低20%-40%，产率的最大降低与萜烯消耗量的最小值（15-30 ppb）同时出现。数据表明产率的绝对降低量约为0.03且保持恒定。对滤膜样品的气相色谱-质谱分析表明，α-蒎烯SOA中发现的主要产物包括有机酸（如松脂酸）、酮酸（如松莰酮酸）和羟基酮酸（如10-羟基松莰酮酸）。基于滤膜结果的分析表明，产率降低是由于在紫外线存在下进行实验时形成了挥发性更高的产物分布。这些结果意味着之前的“暗袋”实验可能高估了单萜烯产生的SOA，并且大气中SOA的产生可能显著取决于光化通量。
