Polycyclic Aromatic Hydrocarbons in the Atmosphere of Two Subtropical Cities in Southeast China: Seasonal Variation and Gas/Particle Partitioning
Aerosol and Air Quality Research
Eighteen polycyclic aromatic hydrocarbons (PAHs) were measured in the gas and particle phase from four sites in two cities, Quanzhou and Xiamen, in Southeast China during January (winter), March (spring), August (summer) and November (fall) 2010. The total concentration in the gas phase ranged from 10.7 ± 2.4 to 507.8 ± 57.0 ng/m 3 , while in the particle phase between 1.4 ± 0.5 and 46.5 ± 19.1 ng/m 3 . The levels of total PAHs (gas + particle) were lower than those recorded for Beijing,
... for Beijing, Shanghai and Guangzhou in China. The seasonal variations of particle phase PAHs were similar to those cities, with high levels in fall-winter and low levels in spring-summer. However, much higher levels of gas phase PAHs were found in summer. Results of correlation studies illustrated that total suspended particle concentrations, ambient temperature and atmospheric mixing height had significant impact on the concentrations of atmospheric PAHs and accounted for the observed seasonal variations. Phenanthrene and fluorine were the most abundant compounds in the urban atmosphere during the sampling period, accounting for approximately 38.9 ± 12.4 and 15.3 ± 6.9%, respectively, of the total PAHs. A good positive relationship was obtained in the log-log plot of K p (the gas to particle partitioning coefficient) against P 0 L (the sub-cooled vapor pressure) with a shallow slope (from -0.836 to -0.6742) greater than -1. Potential sources of PAHs were investigated using diagnostic ratios, which reflected the major sources such as vehicular emissions and coal combustion, although other sources such as direct emissions from industrial activities and evaporation from urban soil and road dust also contributed. The cancer risk from residential oral exposure to atmospheric PAHs in Quanzhou was higher than that in Xiamen, which was much higher than the US EPA risk management criterion (1 × 10 -6 ) during the fall-winter sampling period.