Comparison of atmospheric polycyclic aromatic hydrocarbons (PAHs) over six years at a CAWNET background site in central China: Changes of seasonal variations and potential sources

Abstract

Total suspended particles (TSP) and gaseous samples were collected by using a high-volume sampler from March 2012 to March 2013 and January 2018 to January 2019 at a background site (Jinsha, JSH) in central China to study the chemical characteristics, seasonal variations, and potential sources of polycyclic aromatic hydrocarbons (PAHs). The average concentrations of ∑15PAHs were 24.55 ± 9.19 ng m−3 in 2012/2013 and 20.98 ± 9.77 ng m−3 in 2018/2019. Low-ring PAHs were more concentrated in gas phase while high-ring PAHs were prone into particle phase. The concentrations of PAHs in the two sampling years were high in winter but low in summer and autumn. The relationships between the gas concentrations of PAHs and temperature indicated that most PAHs were influenced by long-range atmospheric transport (LRAT) in 2012/2013 and in 2018/2019, excluding anthracene (Ant) and pyrene (Pyr) were partially affected by air-surface re-volatilization in 2012/2013. The source of atmospheric PAHs at JSH was similar in 2012/2013 and 2018/2019,which was mainly due to the LRAT of PAHs emitted from biomass/fossil fuel combustion in the northern area of JSH. From 2012/2013 to 2018/2019, there was no significant difference between the concentrations of PAHs in spring and winter, whereas the concentrations of PAHs decreased from 2012/2013 to 2018/2019 in summer. In all, the control of PAHs at the source region was partially effective from 2012/2013 to 2018/2019.