2017年春节期间北京市城区和郊区大气PM_(2.5)及其中多环芳烃的污染特征

Characterization of ambient PM_(2.5) and PAHs during 2017 Spring Festival in urban and suburb areas of Beijing

为研究2017年春节期间北京市城区和郊区大气PM_(2.5)及负载多环芳烃(PAHs)的污染水平和污染特征,分别在北京城区和郊区各选一个监测点,采集大气中的PM_(2.5),采用重量法和超声提取-GC/MS对滤膜上的PM_(2.5)及多环芳烃的浓度进行测定.结果表明,春节期间城郊两地的大气PM_(2.5)和PAHs均呈多峰分布,PM_(2.5)均值分别为104.5μg·m^(-3)和104.6μg·m^(-3),无显著性差异;两地PAHs均值差异具有统计学意义(P=0.001).除夕日(CSFE)烟花集中燃放时段PM_(2.5)在城郊两地的日均浓度较前一日非集中燃放日均有明显升高.春节期间PAHs组成以4环和5环为主,二者之和占PAHs总量的80%以上,特征比值法显示城区污染主要来自燃煤和交通尾气的混合源,郊区燃煤占主导.

To investigate the impact of playing fireworks on PM（2.5）and polycyclic aromatic hydrocarbons（PAHs）,daily PM（2.5）samples were collected around 2017 Chinese Spring Festival（CSF）holidays both in urban and suburb areas of Beijing.Gravimetric method and ultrasonicchromatography/mass spectrometry（U-GC/MS）were conducted to analyze the concentrations of PM（2.5）and PAHs respectively.The results showed that PM（2.5）and PAHs presented multi-peak distribution across the whole sampling period at both sampling sites.Tfhe average daily concentrations of PM（2.5）were 104.5μg·m^（-3）and 104.6μg·m^（-3）in urban and suburb,respectively,which showed no significant difference.The total concentration of PAHs in suburb area was much higher than that in urban area.The daily concentrations of PM（2.5）and total PAHs on Chinese Spring Festival Eve（CSFE）increased significantly compared with those before CSFE in both areas.The4-ring and 5-ring PAHs were the most abundant species,contributing more than 80%of the total PAHs.Diagnostic ratios indicated that coal combustion and traffic emission were the main sources of PM（2.5）associated PAHs in urban area,and coal combustion played a more important role in suburb area.