兰州市2011年春节期间颗粒物浓度及其谱分布特征

研究了兰州市2011年1月25日~2月18日春节期间大气颗粒物浓度及其谱分布特征,并通过多元对数正态分布拟合方法对其体积浓度谱特征进行了分析.采用空气动力学粒径谱仪(APS-3321)对颗粒物数浓度及其谱分布进行了实时监测,以阐明兰州市春节期间烟花爆竹燃放对大气颗粒物浓度及其谱分布的影响.结果表明:2011年春节期间兰州市烟花燃放对2月3日~8日颗粒物浓度有不同程度的影响,正月初一00:00~01:00和21:00~22:00时受烟花爆竹燃放影响最大,其中在烟花燃放最为集中时段(2月3日0:00~1:00时)0.5~10μm大气颗粒物平均数浓度、表面积浓度和体积浓度分别为(310.3±97.2)个/cm3、(1061.6±396.0)μm2/cm3和(409.9±176.0)μm3/cm3,分别较未受烟花燃放影响的1月27日~30日0:00~1:00时平均值增加了6.10倍、7.72倍和9.93倍.烟花燃放对数浓度和体积浓度的影响分别主要集中在0.542~1.382μm和3.278~8.354μm粒径段,而对表面积浓度的影响主要集中在0.542~1.981μm和3.278~8.354μm粒径段.受烟花燃放影响的颗粒物体积浓度谱中位径在0.93, 5.50μm左右出现的比例最大,未受烟花燃放影响的颗粒物体积浓度谱中位径在0.85,5.50μm左右出现的比例最大,与未受烟花燃放影响日的颗粒物体积浓度谱相比,燃放烟花使位于积聚模态的体积中位径增加.

Concentration and size distribution of aerosol particles during 2011 Spring Festival in Lanzhou

The air pollution characteristics during the Spring Festival in Lanzhou were investigated. Measurements for particles in the size range 0.5 to 20 μm were taken using a TSI particle sizer from 25th January to 18th February, 2011 in urban Lanzhou. Elevated particle concentrations were observed from 3rd to 8th February, 2011 due to the firework burning. The result showed that the most affected periods by fireworks burning were 00:00~01:00 and 21:00~22:00 on 3rd February 2011. During 00:00~01:00 on 3rd February, the average particle number, surface area and volume concentrations in the size range 0.5~20μm were (310.3±97.2)/cm3, (1061.6±396.0)μm2/cm3 and (409.9±176.0) μm3/cm3, respectively, which were 6.10, 7.72 and 9.93 times higher than that in normal days during the Spring Festival. The firework emissions affected particle concentration in different sizes with different extent. For number and volume concentrations, the most affected size range was 0.542~1.382μm and 3.278~8.354μm, respectively, while for surface area concentrations, the most affected size range were 0.542~1.981μm and 3.278~8.354μm. The volume median diameters for particle volume size distributions in normal days appeared most frequently around 0.85μm and 5.50μm, while that affected by fireworks appeared most frequently around 0.93μm and 5.50μm, indicating the growth of accumulation particles during fireworks burning.