• 关键词：PM_2.5  PAHs  季节变化  气象条件  主成分分析

• 基金项目：国家杰出青年科学基金资助项目(No.20625722);高等学校全国优秀博士学位论文作者专项资金(No.2007B57)

• 段凤魁
• 清华大学环境科学与工程系, 北京 100084

• 贺克斌
• 清华大学环境科学与工程系, 北京 100084

• 马永亮
• 清华大学环境科学与工程系, 北京 100084

• 摘要：采用GC/MS定量分析了2003年9月至2004年7月期间北京市PM_2.5中16种优控PAHs的含量.研究表明,PAHs总浓度年均值139.59ng·m^-3,变化范围1.02～776.4ng·m^-3.冬季浓度最高271.05ng·m^-3,夏季最低26.10ng·m^-3,反映了主要源排放(燃煤)变化与气象条件的共同影响.全年平均不同环数PAHs所占总浓度的比例由大到小:4环>5环>6环>3环>2环;冬季4环PAHs所占比例最大(48.7%),其次为5环(32.5%)和6环PAHs(14.9%);夏季5环、6环PAHs所占比例最高(36.5%),其次为4环PAHs(24.1%).源排放特征化合物比值法和主成分分析法结果都表明,燃煤、机动车和油类挥发是多环芳烃的3类主要污染源,能够解释主成分分析法总方差的88%.

• Abstract：Sixteen polycyclic aromatic hydrocarbons(PAHs) were determined by GC/MS in PM_2.5 samples taken from September 2003 to July 2004 in Beijing.The annual average concentration of the total PAHs was 139.59 ng·m^-3,ranging from 1.02 ng·m^-3 to 776.4 ng·m^-3 and showed strong seasonal variation,that is,the highest value in winter(271.05 ng·m^-3) and the lowest in summer(26.10 ng·m^-3).These results indicate the influence of both main source emission and meteorological conditions.Over the whole year,the average amounts of the different ring PAHs appeared in the following order:4-ring > 5-ring > 6-ring >3-ring > 2-ring.In winter,the percentage of 4-ring PAHs was the highest(48.7%),followed by 5-ring PAHs(32.5%) and 6-ring PAHs(14.9%);in summer,the percentage of 5-ring and 6-ring PAHs(36.5%,together) were higher than 4-ring PAHs(24.1%).Results from both the characteristic ratios of sources and principal component analysis(PCA) indicated that coal burning,gasoline and diesel vehicle emissions were the three main sources of PAHs in PM_2.5 in Beijing.These three sources can explain 88% of the total variance.

• Key words：PM_2.5  PAHs  seasonal variation  meteorological conditions  principal component analysis(PCA)

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