Secondary organic aerosols in Jinan, an urban site in North China: Significant anthropogenic contributions to heavy pollution

Abstract Secondary organic aerosols (SOAs) are an important component of particulates, but whether biogenic SOAs (BSOAs) or anthropogenic SOAs (ASOAs) are the dominant contributors to haze pollution remains poorly characterized. In this study, particulate samples were collected from September 2014 to August 2015 at an urban site in Jinan, which is the capital of Shandong Province and a typical city in the North China Plain. The PM 2.5 samples were analyzed for BSOA (isoprene (SOA I ) and monoterpenes (SOA M )) and ASOA (aromatic (SOA A )) tracers. The concentrations of the SOA A tracer (1.1 ± 1.0 ng/m 3 ) were lowest, and those of SOA I tracers (41.8 ± 86.2 ng/m 3 ) were highest, with the concentrations of SOA M tracers (19.4 ± 9.9 ng/m 3 ) being intermediate. The SOA I tracers were more abundant in the summer and less abundant in the winter. Both SOA I and SOA M increased with increasing ozone level but decreased with increasing NOx level. Correlation analysis revealed a good correlation between 2,3-dihydroxy-4-oxopentanoic acid and levoglucosan levels in three seasons. These results suggested that biomass burning activities occurring in the NCP can enhance the emissions of aromatics and should be controlled, especially in the autumn and winter. SOA tracers were classified according to pollution degree, and the results showed that as pollution increases, the contributions of SOA A increase. These results indicate that reducing anthropogenic emissions is necessary to prevent SOA pollution, especially during heavy pollution episodes.