菏泽市PM2.5源方向解析研究

Source Directional Apportionment of PM_(2.5) in Heze City

为了定量解析环境受体中不同方向PM_(2.5)的源贡献水平,利用"源方向解析"(source directional apportionment,SDA)法[综合PMF(positive matrix factorization,正定矩阵因子)方法和后向轨迹模型]对京津冀大气污染传输通道上某典型城市——菏泽市环境受体中PM_(2.5)进行来源解析,并分析不同方向的源贡献.结果表明,菏泽市环境受体中ρ(PM_(2.5))变化范围为42.73~191.72μg/m^3,平均值为92.54μg/m^3.SO_4^(2-)、NO_3^-和NH_4^+是菏泽市环境受体中PM_(2.5)的主要化学组分;ρ(SO_4^(2-))、ρ(NO_3^-)和ρ(NH_4^+)的平均值分别为29.78、22.11和7.91μg/m^3,三者之和占ρ(PM2.5)的63.54%.PMF的计算结果显示,二次无机盐、机动车排放、扬尘、煤烟尘和建筑水泥尘是菏泽市环境受体中PM_(2.5)的贡献源类,分担率分别为32.61%、22.60%、19.54%、16.25%和9.00%.利用后向轨迹模型识别出PM_(2.5)贡献源类的4个潜在方向,分别为东南、正西、西北和正东.二次无机盐在4个方向的贡献分别为8.49%、5.01%、6.65%和12.88%;机动车排放分别为1.39%、4.44%、7.47%和8.22%;扬尘分别为4.95%、3.65%、4.12%和6.92%;煤烟尘分别为4.56%、1.93%、2.16%和7.28%;建筑水泥尘分别为2.22%、1.88%、1.27%和3.56%.研究显示,菏泽市PM2.5污染较为严重,其中二次源、机动车和扬尘源是其主要贡献源类,并且来自菏泽市东部的各源类贡献均较高.

To quantify contributions from each source-category derived from various direct ions, ambient PM 2.5 data were collected from Heze City,which is a typical city in the Jing-Jin-Ji atmospheric pollution transport channel. The data were analyzed by a method called ‘ source directional apportionment’ （SDA）,combining the positive matrix factorization （PMF） model and backward trajectories cluster analysis. The results showed that the p （ PM2. 5 ） varied in the range of 42. 73-191. 72 μg /m 3 , with an average concentration of 92. 54 μg/m 3 . SO42 ,NO3 and NH 4 ＋ were major compositions of PM 2.5 in Heze City. The average values of p （ SO4 2 ） , p （ NO3 ） and p （ N H 4 ＋ ） were 29. 78,22. 11 and 7. 91 μg/m 3 ,respectively. The sum of three compositions accounted for 6 3 .5 4% of the total p （ PM 2.5 ） . The results of the PMF model indicated that secondary sources （32.61%）,vehicle exhaust （ 22. 60%）,fugitive dust （19.54%）,coal combustion （ 16. 25%） and construction dust （9.00%） were the primary contributors to PM 2.5 in Heze City. Four potential sourcedirections were identified by using backward trajectory analysis during the sampling period. The percentages of source directional contributions from the directions 1 to 4 （ southeast,west, northwest and east） were estimated as follows： secondary sources （ 8 . 4 9 %,5. 0 1 % ,6. 65% and 12. 8 8% ,re s p e c t iv e ly ）,vehicle exhaust （ 1 . 3 9% , 4. 4 4 % , 7. 47% and 8. 2 2 % ,respectively ）, fug itive dust （ 4. 9 5 % , 3. 6 5 % , 4. 12% and 6. 9 2 %, re s p e c t iv e ly ）,coal combustion （4 . 5 6% ,1. 9 3% ,2. 16% and 7. 2 8 %,respectively ） and construction dust （ 2. 2 2%, 1 .8 8 % , 1 .2 7% and 3 .5 6 % , respectively ） . The study suggested that PM 2 5 pollu tio n is serious in Heze City,and that secondary sources, vehicle exhaust and fugitive dust were the major contributors to the air pollution. In addition, all the sources from east of Heze City presented relatively high contributions.