Pollution Characteristics of Polycyclic Aromatic Hydrocarbons in PM_2.5 in Two Urban Areas of Guiyang City

Objective  To describe the pollution characteristics of polycyclic aromatic hydrocarbons (PAHs) in fine particulate matters (PM_2.5) in two urban areas of Guiyang.

Method  PM_2.5 samples were collected in Nanming District with mixed traffic and residents and Huaxi District predominantly oriented to tourism in Guiyang City from October to December 2014. PAHs in 42 PM_2.5 samples were detected and analyzed by characteristic ratios method to identify their structures and origins.

Result  The total PAHs (ΣPAHs) concentrations in PM_2.5 in Nanming District and Huaxi District were in the ranges of (7.12-30.23) ng/m³ and (7.12-24.26) ng/m³, and the average concentrations were (14.72±1.509) ng/m³ and (13.86±1.420) ng/m³ respectively. Benzo(a)pyrene was detected in all samples collected from the two areas with concentration ranges of 0.68-5.04 ng/m³ and 0.38-3.63 ng/m³ respectively. The unqualified rate of daily average concentrations of benzo(a)pyrene for Nanming District was 19.0% and that for Huaxi District was 14.3%. The contributions of PAHs with different chemical structures to the total PAHs concentrations in the two areas varied as follows: 5 rings > 4 rings > 6 rings > 3 rings> 2 rings.

Conclusion  The PAHs in PM_2.5 in Nanming and Huaxi areas of Guiyang City are mainly from coal burning and vehicle emission.