Modeling the atmospheric concentrations of individual gas-phase and particle-phase organic compounds
Modeling the atmospheric concentrations of individual gas-phase and particle-phase organic compounds
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DOI：
10.1021/es9901922
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发表时间：
2000-04-01
影响因子：
11.4
通讯作者：
Cass, GR
中科院分区：
文献类型：
--
作者：
Fraser, MP;Kleeman, MJ;Cass, GR
欧拉光化学风场模型适用于跟踪碳数从C-1到C-34范围内的单个气相、半挥发性和颗粒相化合物的浓度。该模型根据最近的源测试纳入了有机气体和颗粒的初级排放。这些排放是通过光化学空域模型处理的，该模型的化学机制已扩展到显式地跟踪125个单独的气相有机化合物加上11个集中气相化合物组的反应或形成。颗粒相中的主要有机化合物可以从一个集中的主要有机化合物质量类别中随意分解；在本模型应用中，跟踪了31个单独的主要颗粒有机化合物，因为它们从源头运输到接收者空气监测点。该模型被应用于研究1993年9月8日至9日发生的严重光化学烟雾事件期间，洛杉矶周围的加利福尼亚州南海岸空气盆地中有机物的空气质量关系。所有正构烷烃和大多数芳香烃的环境浓度预测在正确的数量级内，超过6个数量级的浓度变化，从最丰富的气相到最不丰富的颗粒物种。对模型性能的正式评估表明，除少数异常值外，所研究的100多种有机化合物的浓度的平均绝对偏差为+/-47%，预测不足的化合物数量(58)与预测过高的化合物数量(46)大致相同。观察到的芳香烃浓度的时间序列被紧密地再现，芳香族前体的甲基乙二醛的生产被跟踪，预测的烯烃浓度由于化学反应和在顺风向输送过程中的稀释而急剧下降，正如在环境监测数据库中所观察到的那样。这种同时解释单个气相和颗粒有机化合物浓度的能力为今后计算大气中二次有机气溶胶的形成和气体/颗粒再分配奠定了基础。
An Eulerian photochemical airshed model is adapted to track the concentrations of individual vapor-phase, semivolatile, and particle-phase compounds over the carbon number range from C-1 to C-34 The model incorporates primary emissions of organic gases and particles from sources based on recent source tests. These emissions are processed through a photochemical airshed model whose chemical mechanism has been expanded to explicitly follow the reaction or formation of 125 individual vapor-phase organic compounds plus 11 lumped vapor-phase compound groups. Primary organic compounds in the particle phase can be disaggregated at will from a lumped primary organic compound mass category; in the present model application, 31 individual primary particulate organic compounds are tracked as they are transported from sources to receptor air monitoring sites. The model is applied to study air quality relationships for organics in California's South Coast Air Basin that surrounds Los Angeles during the severe photochemical smog episode that occurred on September 8-9,1993. The ambient concentrations of all normal alkanes and most aromatic hydrocarbons are predicted within the correct order of magnitude over 6 orders of magnitude concentration change from most abundant gas phase to least abundant particulate species studied. A formal evaluation of model performance shows that, with the exception of a Few outliers, the concentrations of over 100 organic compounds studied were reproduced with an average absolute bias of +/-47% and with roughly equal numbers of compounds underpredicted (58) versus overpredicted (46). The time series of observed aromatic hydrocarbons concentrations are reproduced closely, production of methylglyoxal from aromatic precursors is tracked, and the predicted olefinic hydrocarbon concentrations decline dramatically in concentration due to chemical reaction and dilution during downwind transport as is observed in the ambient monitoring database. This ability to simultaneously account for the concentrations of individual gas-phase and particulate organic compounds lays a foundation for future calculations of secondary organic aerosol formation and gas/particle repartitioning in the atmosphere.