Fine particle-bound polycyclic aromatic hydrocarbons (PAHs) at an urban site of Wuhan, central China: Characteristics, potential sources and cancer risks apportionment.

Levels, compositions, sources, and cancer risks of fine particle (PM2.5)-bound PAHs were investigated at an urban site of Wuhan, Central China. Totally 115 PM2.5 samples collected during four seasons from 2014 to 2015 were analyzed for 16 USEPA priority PAHs. The annual average of PM2.5 and total PAHs were 106 ± 41.7 μg m-3 and 25.1 ± 19.4 ng m-3, respectively. The seasonal levels of PM2.5 and PAHs varied in a similar trend, with the highest concentrations in winter and the lowest in summer. PM2.5-bound PAHs under different pollution level was discussed and the highest average PAH levels were found at a moderate (115-150 μg m-3) air quality level. Three sources including coal combustion and biomass burning, petrogenic source, and vehicle emissions were extracted and quantified by the positive matrix factorization (PMF) model, accounting for 22.7 ± 21.3%, 34.4 ± 29.0% and 42.9 ± 31.3% of the total PAHs, respectively. The potential source contribution function (PSCF) and the concentration-weighted trajectory (CWT) were combined to explore the geographic origins of PAHs. The spatial distributions of coal combustion and biomass burning, petrogenic source, and vehicle emissions were well correlated with medium molecular weight (MMW), low molecular weight (LMW) and high molecular weight (HMW) PAHs, respectively. Results of PSCF and CWT indicated that the long-distance transport form north of Wuhan as far as northern and eastern of China was higher than that from the southern China while the contribution of local areas was higher than those from the long-range transport. The overall lifetime lung cancer risk (LLCR) via inhalation exposure to PM2.5-bound PAHs was estimated as 3.03 × 10-4, with vehicle emissions contributed 57.1% (1.6 × 10-4) to the total risk on average, followed by coal combustion and biomass burning (31.0%, 9.6 × 10-5), and petrogenic source (11.9%, 3.6 × 10-5).