杭州市大气颗粒物消光特性与贡献因子研究

Extinction characteristics of atmospheric particulate matter and the contribution factors in Hangzhou City

2013年12月至2014年12月采集杭州市PM_(2.5)样品,同步观测大气散射系数、吸收系数及气象因子,分析杭州市大气颗粒物消光特性及灰霾天气污染特征。结果表明:观测期间,杭州市大气颗粒物消光系数平均值为566 Mm^(-1),呈现出夏季低冬季高的季节特征。利用修正的IMPROVE公式估算PM_(2.5)中对消光系数有主要贡献的化学组成,得出消光系数的主要贡献者为NH_4NO_3、(NH_4)_2SO_4、颗粒有机物,对消光系数的贡献率分别为31.6%、25.6%、28.9%。灰霾天气下,NH_4NO_3与(NH_4)_2SO_4的消光贡献分别为清洁天气的14.1、10.2倍,说明硝酸盐和硫酸盐可能是杭州市灰霾天气中导致大气能见度下降的主要物质。

To investigate the extinction characteristics of atmospheric particulate matter and the pollution fea- ture of haze days,PM2.5 samples were collected from December 2013 to December 2014 in Hangzhou City. The scat- tering coefficients,absorbing coefficients and meteorological parameters for this period were also measured. The re- suits showed that the average extinction coefficient was 566 Mm-1 .The seasonal variation of extinction coefficients was obvious： the high values were observed in winter and the low values were in summer. The revised IMPROVE equation was used to estimate the major extinction contribution of chemical components. The major contributors to extinction coefficients in Hangzhou City included NH4 NO3 （31.6 % ） , （NH4） 2 SO4 （25.6% ） and particulate organic matter （28.9%）. The contributions of NH4NO3 and （NH4）2SO4 in hazy days were 14.1 and 10.2 times as high as in clean days, respectively,indicating that nitrate and sulfate might be the main factors for visibility degradation on hazy days in Hangzhou City.