[摘要] This paper presents a state-of-the-art gas-phase mechanism for thedegradation of α-pinene by OH and its validation by box modelsimulations of laboratory measurements. It is based on the near-explicitmechanisms for the oxidation of α-pinene and pinonaldehyde byOH proposed by Peeters and co-workers. The extensive set ofα-pinene photooxidation experiments performed in presence as well asin absence of NO by Nozière et al. (1999a) is used to test the mechanism. Thecomparison of the calculated vs measured concentrations as a function of timeshows that the levels of OH, NO, NO
2 and light are wellreproduced in the model. Noting the large scatter in the experimental resultsas well as the difficulty to retrieve true product yields from concentrationsdata, a methodology is proposed for comparing the model and the data. Themodel succeeds in reproducing the average apparent yields of pinonaldehyde,acetone, total nitrates and total PANs in the experiments performed inpresence of NO. In absence of NO, pinonaldehyde is fairly wellreproduced, but acetone is largely underestimated.
The dependence of the product yields on the concentration of NO andα-pinene is investigated, with a special attention on the influence ofthe multiple competitions of reactions affecting the peroxy radicals in themechanism. We show that the main oxidation channels differ largely accordingto photochemical conditions. E.g. the pinonaldehyde yield is estimated to beabout 10% in the remote atmosphere and up to 60% in very polluted areas. Westress the need for additional theoretical/laboratory work to unravel thechemistry of the primary products as well as the ozonolysis andnitrate-initiated oxidation of α-pinene.
