香河地区亚微米气溶胶粒子尺度谱分布特征

Characteristics of Submicron Aerosol Particle Size Spectrum Distribution in Xianghe

为了解香河地区气溶胶尺度谱的基本特征,自2012年5月起,利用扫描电迁移率粒径谱仪(SMPS)对河北香河地区的亚微米(13.8~723.4 nm)气溶胶尺度谱分布进行了近2 a的测量。基于该数据集,分析了气溶胶尺度谱的季节变化和日变化特征及气象要素对气溶胶浓度的影响。结果发现,观测期间埃根核模态(20.0~100.0 nm)、积聚模态(100.0~723.4 nm),以及总的气溶胶数浓度、表面积浓度和体积浓度均值分别为7.0×103cm^(-3)、7.5×103cm^(-3)、14.9×103cm^(-3)、1125μm2·cm^(-3)和50μm^3·cm^(-3)。香河地区积聚模态的粒子数浓度接近华北地区其他污染测站的结果,但高于发达国家的测值。冬季气溶胶的平均浓度最高(18.1×10~3cm^(-3)),而春季最低(12.3×10~3cm^(-3))。不同季节,气溶胶的数谱分布主要为单峰分布,平均峰值直径约为105 nm。气溶胶浓度的日变化受机动车排放的影响显著,存在早晚两个高值中心,分别出现在早上的06:00—09:00和晚上的19:00—21:00。风速、风向对气溶胶数浓度的影响较大,低风速(<2 m/s)和南风条件,尤其是吹西南风时,气溶胶浓度的增加显著。

In order to analyze the basic characteristics of particle number size distribution（ PNSD）in Xianghe,two-year measurements of submicron（ 13. 8—723. 4 nm） PNSD were conducted since May2012 by Scanning Mobility Particle Sizer（ SMPS）. The seasonal and diurnal variations of PNSD and its dependent relationship on meteorological elements were analyzed. The results are as follows. The averaged number concentrations of Aitken mode（ 20. 0—100. 0 nm）,accumulation mode（ 100. 0—723. 4 nm）and total size range during the campaign are 7. 0 × 10^3cm^-3,7. 5 × 10^3cm^（-3） and 14. 9 × 10^3cm^（-3） respectively,and the averaged surface and volume concentration are 1125 μm^2·cm^（-3） and 50 μm^3·cm^（-3） respectively. The number concentrations of accumulation mode particles in Xianghe are similar with that measured in other polluted cities over the North China plain,but generally higher than that in cities of developed countries. The maximum value of seasonal averaged particle number concentrations occurred in winter（ 18. 1 × 10^3cm^（-3））,while the lowest value（ 12. 3 × 10^3cm^（-3）） occurred in spring. The seasonal averaged size distribution of particle number is unimodal with peak diameter around 105 nm. The averaged diurnal variations of particle concentration show two peaks,one appears in 06： 00—09： 00 and the other in19： 00—21： 00 indicating the strong influence from traffic emission. Wind plays an important role in variation of particle concentration. Low wind speed（ 2 m / s） and southern wind,especially southwest wind,significantly contribute to the accumulation of particles.