Trend of Polycyclic Aromatic Hydrocarbons in Atmospheric PM_2.5 in Two Districts of Ji'nan from 2014 to 2017

Objectives To study and analyze the trend of polycyclic aromatic hydrocarbons (PAHs) in atmospheric PM_2.5 in 2014-2017 in two districts of Ji'nan.

Methods A total of 738 effective PM_2.5 samples were collected in 2014-2017 from Licheng district (polluted area) and Shizhong district (control area) in Jinan. PAHs were examined by ultra-high performance liquid chromatography. Interregional time and seasonal variation in PAHs were analyzed.

Results The seasonal variation of average PAHs concentration in Ji'nan was obvious (winter > autumn > spring > summer). Most components of PAHs in the atmosphere of Ji'nan were more than 4 rings accounting for more than 90% of the total. The pollution level of PAHs in Licheng district (polluted area) was significantly higher than that in Shizhong district (control area). (U=58 041.0, P < 0.05). Coal combustion and motor vehicle emission were the main source of PAHs pollution in two districts in Ji'nan.

Conclusions The concentration of PAHs in the atmosphere has been decreasing year after year in two districts in Ji'nan, but the overall effectiveness was still not optimistic.