To understand the pollution characteristics of aromatic compounds in Shijiazhuang, PM2.5 samples were collected day and night for 30 days from September 18 to October 17, 2016. Qualitative and quantitative analyses were conducted using gas chromatography-mass spectrometry (GC-MS). The results showed that total average concentration of aromatic compounds was 33.5 ng·m-3, lower than that of levoglucosan (487 ng·m-3). Concentration of nitro-aromatic compounds was the highest (20.4 ng·m-3), followed by aromatic acids (9.94 ng·m-3) and aromatic aldehydes (3.14 ng·m-3). Influenced by the decrease in the boundary layer and temperature, concentration of 8 substances during night was higher than during the day. There was a significant positive correlation between levoglucosan and nitro-aromatic, aromatic aldehyde, and aromatic acid compounds, with correlation coefficients (r) of 0.6829, 0.6443, and 0.6782, respectively, indicating that biomass burning is an important primary source of aromatic compounds that directly affects their concentrations in the atmosphere. Based on the analysis of daily variation trends in total concentration of aromatic compounds and the backward trajectory model, it was found that the pollution of aromatic compounds in Shijiazhuang in autumn was affected by regional transportation and local emissions.
Keywords: PM2.5; aromatic acids; aromatic aldehydes; aromatic compounds; nitro-aromatic compounds.