Ma Qiao, Lin Xiaoxiao, Yang Chengqiang, Long Bo, Gai Yanbo, Zhang Weijun
Laboratory of Atmospheric Physico-Chemistry, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, People's Republic of China.
University of Science and Technology of China, Hefei 230026, People's Republic of China.
R Soc Open Sci. 2018 May 2;5(5):172171. doi: 10.1098/rsos.172171. eCollection 2018 May.
The influences of ammonia (NH) on secondary organic aerosol (SOA) formation from ozonolysis of styrene have been investigated using chamber experiments and quantum chemical calculations. With the value of [O]/[styrene] ratios between 2 and 4, chamber experiments were carried out without NH or under different [NH]/[styrene] ratios. The chamber experiments reveal that the addition of NH led to significant decrease of SOA yield. The overall SOA yield decreased with the [NH]/[styrene] increasing. In addition, the addition of NH at the beginning of the reaction or several hours after the reaction occurs had obviously different influence on the yield of SOA. Gas phase reactions of Criegee intermediates (CIs) with aldehydes and NH were studied in detail by theoretical methods to probe into the mechanisms behind these phenomena. The calculated results showed that 3,5-diphenyl-1,2,4-trioxolane, a secondary ozonide formed through the reactions of CHĊHOO· with CHCHO, could make important contribution to the aerosol composition. The addition of excess NH may compete with aldehydes, decreasing the secondary ozonide yield to some extent and thus affect the SOA formation.
利用腔室实验和量子化学计算，研究了氨（NH₃）对苯乙烯臭氧分解形成二次有机气溶胶（SOA）的影响。在[O₃]/[苯乙烯]比值为2至4的情况下，在无NH₃或不同[NH₃]/[苯乙烯]比值条件下进行了腔室实验。腔室实验表明，添加NH₃导致SOA产率显著降低。总体SOA产率随[NH₃]/[苯乙烯]的增加而降低。此外，在反应开始时或反应发生数小时后添加NH₃对SOA产率有明显不同的影响。通过理论方法详细研究了Criegee中间体（CIs）与醛和NH₃的气相反应，以探究这些现象背后的机制。计算结果表明，由CH₂OO·与CH₃CHO反应形成的二级臭氧化物3,5 - 二苯基 - 1,2,4 - 三氧杂环戊烷可能对气溶胶成分有重要贡献。添加过量的NH₃可能与醛竞争，在一定程度上降低二级臭氧化物产率，从而影响SOA的形成。
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