Song Chen, Na Kwangsam, Warren Bethany, Malloy Quentin, Cocker David R
Bourns College of Engineering-Center for Environmental Research and Technology (CE-CERT), University of California, Riverside, California 92521, USA.
Environ Sci Technol. 2007 Oct 15;41(20):6990-5. doi: 10.1021/es062279a.
Propene is widely used in smog chamber experiments to increase the hydroxyl radical (OH) level based on the assumption that the formation of secondary organic aerosol (SOA) from parent hydrocarbon is unaffected. A series of m-xylene/NO(x) photooxidation experiments were conducted in the presence of propene in the University of California CE-CERT atmospheric chamber facility. The experimental data are compared with previous m-xylene/N0(x) photooxidation work performed in the same chamber facility in the absence of propene (Song et al. Environ. Sci. Technol. 2005, 39, 3143-3149). The result shows that, for similar initial conditions, experiments with propene have lower reaction rates of m-xylene than those without propene, which indicates that propene reduces OH in the system. Furthermore, experiments with propene showed more than 15% reduction in SOA yield compared to experiments in the absence of propene. Additional experiments of m-xylene/ NO(x) with CO showed similar trends of suppressing OH and SOA formation. These results indicate that SOA from m-xylene/NO(x) photooxidation is strongly dependent on the OH level present, which provides evidence for the critical role of OH in SOA formation from aromatic hydrocarbons.
基于母体碳氢化合物生成二次有机气溶胶（SOA）不受影响这一假设，丙烯在烟雾箱实验中被广泛用于提高羟基自由基（OH）水平。在加利福尼亚大学CE - CERT大气箱设施中，在丙烯存在的情况下进行了一系列间二甲苯/氮氧化物（NOₓ）光氧化实验。将实验数据与之前在同一箱设施中在无丙烯情况下进行的间二甲苯/氮氧化物光氧化研究（Song等人，《环境科学与技术》，2005年，39卷，3143 - 3149页）进行了比较。结果表明，在相似的初始条件下，有丙烯参与的实验中间二甲苯的反应速率低于无丙烯参与的实验，这表明丙烯降低了体系中的OH。此外，与无丙烯参与的实验相比，有丙烯参与的实验中SOA产率降低了超过15%。间二甲苯/氮氧化物与一氧化碳（CO）的额外实验显示出抑制OH和SOA形成的类似趋势。这些结果表明，间二甲苯/氮氧化物光氧化产生的SOA强烈依赖于体系中存在的OH水平，这为OH在芳烃形成SOA过程中的关键作用提供了证据。
