Investigation of α-Pinene + Ozone Secondary Organic Aerosol Formation at Low Total Aerosol Mass
Investigation of α-Pinene + Ozone Secondary Organic Aerosol Formation at Low Total Aerosol Mass
复制标题
低气溶胶总质量下 α-蒎烯 + 臭氧二次有机气溶胶形成的研究
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发表时间：
2006
期刊：
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通讯作者：
N. Donahue
中科院分区：
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作者：
A. Presto;N. Donahue
提出了一种利用质子转移反应质谱（PTR-MS）测量低总有机物质量浓度（COA）下二次有机气溶胶（SOA）产生的方法。PTR-MS提供气相有机物的高时间分辨率测量，并与颗粒测量相结合，允许在真实的时间内确定气溶胶产量。这种方法有利于在低COA下测量气溶胶产生;事实上，气溶胶质量分数可以在α-蒎烯消耗期间测量，而不是仅在气相化学完成时测量。高时间分辨率数据与Pankow（Atmos. Environ. 1994，28，185和189）和先前的实验测量。实验包括紫外线照射和氮氧化物的影响，揭示了α-蒎烯+臭氧产品的光化学和挥发性的其他功能。高时间分辨率的数据还阐明了在COA < 10 microg m（-3）时α-蒎烯臭氧分解产生的气溶胶，并表明目前的分配模型外推到低COA条件下显著低估了在黑暗、低NOx条件下SOA的产生。然而，目前的模型外推高估SOA生产照明下，高氮氧化物的污染区域空气质量的典型条件。
We present a method for measuring secondary organic aerosol (SOA) production at low total organic mass concentration (COA) using proton-transfer reaction mass spectrometry (PTR-MS). PTR-MS provides high time resolution measurements of gas-phase organic species and, coupled with particle measurements, allows for the determination of aerosol yield in real time. This approach facilitates the measurement of aerosol production at low COA; in fact aerosol mass fractions can be measured during alpha-pinene consumption as opposed to only at the completion of gas-phase chemistry. The high time resolution data are consistent with both the partitioning theory of Pankow (Atmos. Environ. 1994, 28,185 and 189) and the previous experimental measurements. Experiments including the effect of UV illumination and NOx reveal additional features of alpha-pinene + ozone product photochemistry and volatility. The high time resolution data also elucidate aerosol production from alpha-pinene ozonolysis at COA < 10 microg m(-3) and show that extrapolations of current partitioning models to conditions of low COA significantly underestimate SOA production under dark, low-NOx conditions. However, extrapolations of current models overestimate SOA production under illuminated, higher-NOx conditions typical of polluted regional air masses.