| 光化学烟雾箱的表征及初步应用 |
| 摘要点击 2164 全文点击 4308 投稿时间：2010-03-18 修订日期：2010-05-06 |
| 查看HTML全文
查看全文 查看/发表评论 下载PDF阅读器 |
| 中文关键词 烟雾箱表征 臭氧 二次有机气溶胶 ·OH MCM机制 |
| 英文关键词 chamber characterization ozone secondary organic aerosol(SOA) ·OH MCM mechanism |
|
| 中文摘要 |
| 介绍了一套自制的用于光化学臭氧和二次有机气溶胶生成研究的室内烟雾箱系统，对该烟雾箱系统进行了一系列表征实验，包括活性物种的壁损失速率常数的测定，以及由CO-NOx光氧化实验确定的反应器内·OH源，并进行了乙烯-NOx和苯-NOx光氧化的初步实验.结果表明，O3和NO2在新反应袋中壁损失受湿度影响很小，而在旧反应袋中影响较大.在旧反应袋中，当湿度分别为5%和91%时，臭氧壁损失速率常数对应为1.0×10-5 s-1和4.0×10-5 s-1；而NO2在旧反应袋中壁损失速率常数在湿度为5%和75%时分别为1.0×10-6 s-1和0.6×10-6 s-1.通过CO-NOx光氧化实验确定了低湿（RH = 5%）和高湿（RH 75%～77%）时，kNO2→HONO分别为(4.2～5.2)×10-5 s-1和(2.3～2.5)×10-5 s-1，该值与文献中报道的结果一致.通过CO与·OH的反应速率常数估算了反应器内·OH的平均浓度为(2.1±0.4)×106 molecules/cm3.分析了各个辅助反应对臭氧生成的灵敏度，发现NO2→HONO在反应起始阶段对臭氧影响最大，而N2O5+ H2O → 2HNO3对臭氧峰值有明显的消减作用，而O3与NO2的壁损失对O3的影响很小.乙烯-NOx以及苯-NOx光氧化实验结果与MCM数值模拟比较一致，反映了烟雾箱在研究VOC光化学产生O3和SOA等二次污染时的可靠性，表明所用烟雾箱装置可以用于大气化学反应过程的深入研究. |
| 英文摘要 |
| A self-made new indoor environmental chamber facility for the study of atmospheric processes leading to the formation of ozone and secondary organic aerosols has been introduced and characterized. The characterization experiments include the measurements of wall effects for reactive species and the determination of chamber dependent ·OH radical sources by CO-NOx irradiation experiments. Preliminary ethene-NOx and benzene-NOx experiments were conducted as well. The results of characterization experiments show that the wall effects for O3 and NO2 in a new reactor are not obvious. Relative humidity has a great effect on the wall losses in the old reactor, especially for O3. In the old reactor, the rate constant for O3 wall losses is obtained to be 1.0×10-5 s-1(RH=5%) and 4.0×10-5 s-1(RH=91%), whereas for NO2 it is 1.0×10-6 s-1（RH=5%）and 0.6×10-6 s-1（RH=75%）. The value for kNO2→HONO determined by CO-NOx irradiation experiments is (4.2-5.2)×10-5 s-1 and (2.3-2.5)×10-5 s-1 at RH = 5% and RH 75%-77%, respectively. The average ·OH concentration is estimated to be (2.1±0.4)×106 molecules/cm3 by using a reaction rate coefficient of CO and ·OH. The sensitivity of chamber dependent auxiliary reactions to the O3 formation is discussed. Results show that NO2 → HONO has the greatest impact on the O3 formation during the initial stage, N2O5 + H2O → 2HNO3 has a minus effect to maximum O3 concentration, and that the wall losses of both O3 and NO2 have little impact on the O3 formation. The results from the ethene-NOx and benzene-NOx experiments are in good agreement with those from the MCM simulation, which reflects that the facility for the study of the formation of secondary pollution of ozone and secondary organic aerosols is reliable. This demonstrates that our facility can be further used in the deep-going study of chemical processes in the atmosphere. |
