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):7046-54. doi: 10.1021/es050400s.
We report secondary organic aerosol (SOA) yields from the ozonolysis of alpha-pinene in the presence of NO and NO2. Experimental conditions are characterized by the [VOC]0/ [NOx]0 ratio (ppbC/ppb), which varies from approximately 1 to approximately 300. SOA yield is constant for [VOC]0/[NOx]0 > approximately 15 and decreases dramatically (by more than a factor of 4) as [VOC]0/[NOx]0 decreases. Aerosol production is completely suppressed in the presence of NO for [VOC]0/[NOx]0 < or = 4.5. Fouriertransform IR analysis of filter samples reveals that nitrate-containing species contribute significantly to the total aerosol mass at low [VOC]0/[NOx]0. Yield reduction is a result of the formation of a more volatile product distribution as [VOC]0/[NOx]0 decreases; we propose that the change in the product distribution is driven by changes in the gas-phase chemistry as NOx concentration increases. We also present two-product model parameters to describe aerosol production from the alpha-pinene/0/NOx system under both high- and low-NOx conditions.
我们报告了在存在NO和NO₂的情况下，α-蒎烯臭氧分解产生的二次有机气溶胶（SOA）产率。实验条件以[VOC]₀/[NOₓ]₀比值（ppbC/ppb）为特征，该比值从约1变化到约300。当[VOC]₀/[NOₓ]₀ > 约15时，SOA产率恒定，而随着[VOC]₀/[NOₓ]₀降低，SOA产率急剧下降（超过4倍）。当[VOC]₀/[NOₓ]₀ ≤ 4.5时，在NO存在下气溶胶生成被完全抑制。对滤膜样品的傅里叶变换红外分析表明，在低[VOC]₀/[NOₓ]₀时，含硝酸盐物种对总气溶胶质量有显著贡献。产率降低是由于随着[VOC]₀/[NOₓ]₀降低形成了更易挥发的产物分布；我们认为产物分布的变化是由随着NOₓ浓度增加气相化学变化驱动的。我们还给出了双产物模型参数，以描述在高NOₓ和低NOₓ条件下α-蒎烯/ O₃/NOₓ体系的气溶胶生成情况。
