灰霾天气下北京海淀城区空气中溴代二恶英在不同粒径颗粒物上的分布特征研究

Particle size distribution of polybrominated dibenzo-p-dioxins and dibenzofurans during haze episodes in urban air in Haidian district,Beijing

采用大气颗粒物分级采样器在同一地点连续采集灰霾天北京海淀城区空气样品,调研了空气中溴代二恶英(PBDD/Fs)的污染水平和在不同粒径颗粒物上的分布特征。研究结果表明:灰霾天城区空气样品中PBDD/Fs的质量浓度为1 535~6 053 fg/m3;PBDD/Fs的浓度随着颗粒物粒径(aerodynamic diameter,dae)的减小而增加,在d_(ae)<1.0μm的颗粒物上浓度最高,80%以上的PBDD/Fs分布在dae<2.5μm的颗粒物上;PBDD/Fs在不同粒径颗粒物上的含量不等,但均以高溴代二苯并呋喃(PBDFs)为主,且其所占比例随颗粒物粒径的增加而减小,然而多溴代二苯并-对-二恶英(PBDDs)在不同粒径颗粒物上的分布差异性却不显著。

The concentration level and particle size distribution of polybrominated dibenzo-p-dioxins and dibenzofurans（ PBDD/Fs） in urban ambient air in Haidian district in Beijing during haze episodes have been determined by continuously collecting samples at one site. The results showed that the PBDD/Fs concentrations ranged from1 535 to 6 053 fg/m3. The concentrations of PBDD/Fs increased as the particle size decreased. The highest PBDD/Fs concentration was found in the aerodynamic particle diameter（ labelled dae） range 〈1. 0 μm and more than80% of the PBDD/Fs were found in the range dae 〈2. 5 μm particles. The concentrations on the different size of particles were found to vary,and the contributions of the higher brominated dibenzofurans to the total PBDD/Fs concentrations decreased as the particle size increased,but that was not the case for the polybrominated dibenzo-pdioxins.