贵阳市两城区大气PM_(2.5)中多环芳烃的污染特征

Pollution Characteristics of Polycyclic Aromatic Hydrocarbons in PM2.5 in Two Urban Areas of Guiyang City

[目的]探讨贵阳市城区大气细颗粒物(PM_(2.5))中多环芳烃(PAHs)的污染特征。[方法]选择贵阳市交通居民混杂的南明区和以旅游为主的花溪区为采样点,分别于2014年10—12月份采样,共测定42个PM_(2.5)样品中PAHs的含量,采用特征比值法分析PAHs的结构和来源。[结果]南明、花溪两城区PM_(2.5)中PAHs总浓度分别为(7.12~30.23)、(7.12~24.26)ng/m^3,平均浓度分别为(14.72±1.51)、(13.86±1.42)ng/m^3;两个区的大气PM_(2.5)样品中均检出苯并[a]芘,浓度分别为0.68~5.04 ng/m^3、0.38~3.63 ng/m^3,日均浓度超标率分别为19.0%、14.3%;两城区不同化学结构PAHs对总浓度的贡献不同,均为5环>4环>6环>3环>2环。[结论]贵阳市南明、花溪两城区PM_(2.5)中PAHs主要来源于燃煤和车辆排放。

[ Objective ] To describe the pollution characteristics of polycyclic aromatic hydrocarbons （PAHs） in fine particulate matters （PM2.5） in two urban areas of Guiyang. [ Methods ] PM2.5 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 PM2.5 samples were detected and analyzed by characteristic ratios method to identify their structures and origins. [ Results ] The total PAHs （∑ PAHs） concentrations in PM2.5 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 tings 〉6 tings 〉3 rings〉2 rings. [ Conclusion ] The PAHs in PM2.5 in Nanming and Huaxi areas of Guiyang City are mainly from coal burning and vehicle emission.