兰州市城区大气PM_(2.5)中多环芳烃的分布特征

Distribution Characteristics of PAHs in Ambient PM_(2.5) in Urban Area of Lanzhou

目的了解兰州市城区大气细颗粒物(PM_(2.5))中多环芳烃(PAHs)的污染水平及分布特征。方法选择兰州市西固区和城关区作为采样点,于2015年1月—2016年12月期间周期性采集大气PM_(2.5)样品342份,利用高效液相色谱仪测定分析其中PAHs含量。结果 PM_(2.5)日平均质量浓度采暖期高于非采暖期,差异具有统计学意义(P<0.01)。总PAHs质量浓度2015年高于2016年;城关区高于西固区;采暖期高于非采暖期,差异均具有统计学意义(P<0.05)。检出的15种PAHs单体中,苯并[a]芘(Bap)日平均质量浓度约为世界卫生组织规定限值(1.0 ng/m^3)的90倍。结论兰州市城区大气PM_(2.5)中PAHs污染水平较高,PAHs的分布具有时空性。

Objective To investigate the pollution levels and distribution characteristics of polycyclic aromatic hydrocarbons（ PAHs） in ambient PM（2.5） in urban area of Lanzhou. Methods A total of 342 ambient air samples were collected periodically from January 2015 to December 2016,and the concentrations of PAHs in PM（2.5） was determined by HPLC. Xigu and Chengguan Districts in Lanzhou were selected as sampling points. Results The average daily concentration of PM（2.5） in heating period was higher than that in non-heating period（ P 0. 01）. Total PAHs concentration in 2015 was higher than that in 2016,which was higher in Chengguan District than that in Xigu District,as well as higher in heating period than that in non-heating period（ P 0. 05）. Fifteen kinds of PAHs monomer were detected. The average daily concentration of benzo [a] pyrene（ Bap） was found to be 90 times higher than the limit value（ 1. 0 ng/m^3） specified by the World Health Organization. Conclusion The pollution of PAHs in ambient air of Lanzhou was serious and the distribution of PAHs had a space-time characteristics.