北京2008奥运期间PM10的单颗粒形貌类型及生物活性研究

采集2008年北京奥运会期间大气PM_(10)和PM_(2.5)样品,计算质量浓度,得出奥运会期间大气污染水平.利用场发射扫描电镜(FESEM)和图像分析技术对PM_(10)和PM_(2.5)的形貌特征和粒度分布进行分析.同时应用质粒DNA 评价法研究了奥运会期间PM_(10)样品的生物活性.结果表明,奥运会期间可吸入颗粒物质量浓度日均值均符合国家2级标准,PM_(2.5)和PM_(10)的比值为0.63,以细粒子PM_(2.5)为主.奥运期间PM_(10)和PM_(2.5)样品的微观形貌主要为球形颗粒、烟尘集合体、不规则矿物和未知细颗粒,其中球形颗粒和未知细颗粒占有相当大的数量比例.PM_(10)和PM_(2.5)数量-粒度呈单峰分布,主要分布在0.1～0.4 μm范围内.PM_(10)的体积-粒度呈双峰分布,主要分布在0.4～0.5 μm和1～2.5 μm范围内,PM_(2.5)主要分布在1～2.5 μm范围内.质粒DNA 评价结果表明,北京2008奥运期间可吸入颗粒物生物活性明显降低,要达到20%的损伤需要的颗粒物剂量浓度在180 μg·mL~(-1)以上,明显高于2004年的63 μg·mL~(-1),可见奥运期间大气颗粒物对人体危害比往年减小.

Individual Particle Morphology and Bioreactivity of PM10 in Beijing During the 2008 Olympic Games

Inhalable particulates, including PM_(10) and PM_(2.5), were collected on the campus of China University of Mining and Technology during the Summer Olympic Games of Beijing in 2008. The mass concentrations of PM_(10) and PM_(2.5)were monitored. The morphology and size distribution of individual particles in PM_(10) and PM_(2.5) were investigated by a high-resolution Field Emission Scanning Electron Microscopy (FESEM) and image analysis (IA). The toxicity reflected by bioreactivity of PM_(10) during the Olympic Games was also studied by Plasmid DNA assay. The results showed that the mass levels of PM_(10) and PM_(2.5) were well below 81.6 μg·m~(-3) and 54.6 μg·m~(-3), meeting the second ambient air quality standard of China. The ratio of PM_(2.5) and PM_(10) was averaged 0.63, indicating that the PM_(10) is dominated by fine particles. In terms of microscopic morphology, four types of particles were identified, including spherical particles, soot aggregates, minerals and unresolved fine particles, with the spherical particles and unresolved particles being the predominant components. Most PM_(10) and PM_(2.5) particles were in the size range of 0.1-0.4 μm, displaying a unimodal pattern. Volume-size distribution of PM_(10) exhibited a bimodal pattern with the peaks in 0.4-0.5 μm and 1-2.5 μm, and PM_(2.5) particles were mainly concentrated in the range of 1-2.5 μm. The results from plasmid assay showed that the bioreactivity of PM_(10) during the Olympic games was obviously lower than those of past summers, with the TD20 (toxic dosage of PM_(10)causing 20% plasmid DNA damage) being higher than those of the past summers.