NO_x与NMHC的变化对O_3生成量的影响

Impacts of Changes in the Concentration of Nonmethane Hydrocarbon (NMHC) and NOx on Amount of Ozone Formation

利用ＬＬＡ － Ｃ 光化学反应机制， 在 ＮＯｘ 体积分数 φ变化范围很广（１ ．７５ ～３５０ ．０ ，单位为１０ － ９ ，以下同） 的条件下，选择１８ 种ＮＭＨＣ 与ＮＯｘ 的体积分数比（２ ．０ ～２００ ．０） 模拟分析在什么条件下ＮＭＨＣ 的改变对臭氧生成量不大敏感而主要依赖于ＮＯｘ 的大小，同时给出相应条件下ＯＨ 模拟值的变化。结果表明，ＯＨ 峰值均出现在φ（ＮＭＨＣ／ＮＯｘ） ≈８ ．０ 。所找条件是φ（ ＮＯｘ） ≤５０ ．０ 时要求φ（ ＮＭＨＣ／ＮＯｘ） ≥６０ ．０ ； φ（ＮＯｘ） ＞ ５０ ．０ 时需要８ ．０ ≤φ（ＮＭＨＣ／ＮＯｘ） ≤２８ ．０ 。相应Ｏ３ 生成量的最大误差小于２０ ％ 。该条件正适合我国典型污染城市当前φ（ＮＯｘ） 水平和φ（ ＮＭＨＣ／ ＮＯｘ） 范围，可用于我国区域尺度空气质量模拟。与实测资料的对比还有待进一步开展。

Using the LLA-C mechanism, a box model, we have simulated changes in the concentration of O 3 and OH under a broad variety of eighteen initial reactant conditions of [NMHC]/NO x ratios (2.0 to 200.0) and NO x levels (1.75 to 350.0, the unit in the paper is volume ratio 10 -9 unless specified) to find a suitable condition under which the amount of ozone formed is not sensitive to changes in the amount of NMHC but strongly dependent on the concentration of NO x . Simulations indicate that the maximum OH concentration always occurs at φ(NMHC/NO x )≈8.0 under all NO x levels and that the demanded condition is φ(NMHC/NO x )≥60.0 while φ(NO x )≤50.0 and 8.0≤φ(NMHC/NO x )≤28.0 while φ(NO x )>50.0. The current NO x levels and NMHC/NO x ratios in the air over typical urban polluted areas in China happen to lie within this range. This implies that the condition may be suitable for regional air quality simulation in China. Further comparison with field measurements is still needed.