Distribution characteristic, source apportionment and carcinogenic risk of polycyclic aromatic hydrocarbons in PM_2.5 in Hefei

Objective To explore the spatial, temporal and seasonal variations of polycyclic aromatic hydrocarbons (PAHs) in atmospheric fine particulate matter (PM_2.5) in Hefei, China, analyze its emission sources and evaluate its carcinogenic risks.

Methods Airborne PM_2.5 samples were collected from January 2019 to December 2020, and the concentrations of 16 kinds of PAHs in the samples were detected byhigh performance liquid chromatography(HPLC). Diagnostic ratios(DR) and positive matrix factorization(PMF) were used to identify emission sources of PAHs, and assess, their lifetime risk of carcinogenesis.

Results The mass concentrations of total polycyclic aromatic hydrocarbons (∑PAHs) in PM_2.5 ranged from 0.24 to 39.85 ng/m³, with mean concentration of ∑PAHs in winter (8.12 ng/m³)>autumn (5.22 ng/m³)>spring (4.42 ng/m³)>summer (3.17 ng/m³). The mean concentration of ∑PAHs in winter was 2.56 times as more as that in summer. Ratio of anthracene/(anthracene +Phenanthrene) was greater than 0.1 in most samples, and extracted sources contributions of gasoline and coal combustion were 25.7-49.4% and 29.7-39.0%, respectively. The median total incremental lifetime carcinogenic risk of adults and children in winter were 5.24×10^-9 and 0.89×10^-9.

Conclusion The concentration of ∑PAHs in PM_2.5 in Hefei shows seasonal variation, with the highest concentration in winter. The main sources of PAHs are gasoline, automobile exhaust and coal combustion, and the carcinogenic risk of children and adults are within acceptable limits.