Evaluation of alkene degradation in the detailed tropospheric chemistry mechanism, MCM v3, using environmental chamber data
Evaluation of alkene degradation in the detailed tropospheric chemistry mechanism, MCM v3, using environmental chamber data
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DOI：
10.1007/s10874-006-9025-y
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发表时间：
2006-07
影响因子：
2
通讯作者：
P. Pinho;C. Pio;William P. L. Carter;Michael E. Jenkin
中科院分区：
文献类型：
--
作者：
P. Pinho;C. Pio;William P. L. Carter;Michael E. Jenkin
在主化学机理（MCM v3）的第3版中的烯烃降解的代表性进行了评估，使用环境室数据的光氧化的乙烯，丙烯，1-丁烯和1-己烯在NOx的存在下，从多达五个室在全州空气污染研究中心（SAPRC）在加州大学。作为该评价的一部分，有必要包括烯烃与O（3 P）的反应的表示，该反应在室条件下是显著的，但在大气条件下通常是不显著的。乙烯和丙烯系统的模拟，特别是，被认为是敏感的分支比分配到分子和自由基形成途径的O（3 P）反应，自由基形成的程度所需的模型的适当拟合室数据大大低于报告的共识。在这种约束下，乙烯和丙烯的MCM v3机理通常表现良好。还考虑了模拟对一系列其他自由基源和汇反应（烯烃臭氧分解反应和产物羰基光解的自由基形成; OH与NO2反应和β-羟基硝酸盐形成的自由基去除）参数的敏感性，并讨论了这些结果的影响。发现使用仅来自一个腔室的更有限的数据集对MCM v3 1-丁烯和1-己烯降解机制的评价是不确定的。敏感性研究的结果表明，这是不可能调和的模拟和观察到的臭氧在这些系统中的参数值的范围内，目前可以证明的基础上，文献。作为这项工作的结果，差距和不确定性的动力学，机械和腔室数据库的确定和讨论，在对流层化学和化学重要的腔室条件下，可能会损害评估程序，并建议为今后的实验研究。在整个研究过程中，MCM v3化学的性能也同时与SAPRC-99机制中相应化学的性能进行了比较，SAPRC-99机制是结合腔室数据集开发和优化的。
The representation of alkene degradation in version 3 of the Master Chemical Mechanism (MCM v3) has been evaluated, using environmental chamber data on the photo-oxidation of ethene, propene, 1-butene and 1-hexene in the presence of NOx, from up to five chambers at the Statewide Air Pollution Research Center (SAPRC) at the University of California. As part of this evaluation, it was necessary to include a representation of the reactions of the alkenes with O(3P), which are significant under chamber conditions but generally insignificant under atmospheric conditions. The simulations for the ethene and propene systems, in particular, were found to be sensitive to the branching ratios assigned to molecular and free radical forming pathways of the O(3P) reactions, with the extent of radical formation required for proper fitting of the model to the chamber data being substantially lower than the reported consensus. With this constraint, the MCM v3 mechanisms for ethene and propene generally performed well. The sensitivity of the simulations to the parameters applied to a series of other radical sources and sink reactions (radical formation from the alkene ozonolysis reactions and product carbonyl photolysis; radical removal from the reaction of OH with NO2and β-hydroxynitrate formation) were also considered, and the implications of these results are discussed. Evaluation of the MCM v3 1-butene and 1-hexene degradation mechanisms, using a more limited dataset from only one chamber, was found to be inconclusive. The results of sensitivity studies demonstrate that it is impossible to reconcile the simulated and observed formation of ozone in these systems for ranges of parameter values which can currently be justified on the basis of the literature. As a result of this work, gaps and uncertainties in the kinetic, mechanistic and chamber database are identified and discussed, in relation to both tropospheric chemistry and chemistry important under chamber conditions which may compromise the evaluation procedure, and recommendations are made for future experimental studies. Throughout the study, the performance of the MCM v3 chemistry was also simultaneously compared with that of the corresponding chemistry in the SAPRC-99 mechanism, which was developed and optimized in conjunction with the chamber datasets.