可吸入颗粒物生物活性及其微观特征分析

Bioreactivity of Inhalale Particles and Analysis from Its Microscopic Characteristics

采用质粒DNA评价法研究了2004年春季北京市区和郊区上甸子（本底区）PM10的生物活性．结果表明，郊区上甸子2个PM10的TD20值（引起20％质粒DNA损伤所需要的颗粒物剂量）分别为53μg·mL^-1和〈50μg·mL^-1，市区2个PM10的TD20值分别为125μg·mL^-1和100μg·mL^-1，说明郊区PM10的生物活性明显高于市区．同时利用高分辨率场发射扫描电镜（FESEM）和图像分析技术，从PM10微观特征上进行了生物活性差异的原因分析，认为其原因有：①上甸子PM10中以细颗粒物为主，在0～0．7μm粒度范围内的细颗粒物的数量百分含量明显高于市区PM10，而表面积则在0～1．0μm的范围内高于市区；②市区PM10中以粒度较大的矿物颗粒物为主，而上甸子PM10则以生物活性较大的烟尘为主，数量百分含量高达58．8％．因此PM10质量浓度并非评价可吸入颗粒物健康效应的唯一指标，颗粒物的粒度分布和类型可能在其生物活性中起重要作用．

Plasmid DNA assay was employed to investigate the bioreactivity of PM10 collected at urban site and suburban site Shangdianzi in Beijing in spring, 2004. The results showed that the values of TD20 （the dosage of PM10 that caused 20% DNA damage） of the two PM10 samples collected at Shangdianzi site were 53μg·mL^-1 and less than 50μg· mL^-1 respectively and that of the two PM10 collected at urban site were 125μg·mL^-1 and 100μg·mL^-1 respectively, showing that the bioreactivity of suburban PM10 samples was distinctly higher than that of urban PM10. Using high solution Field Emission Scanning Electron Microscopy （FESEM） and image analysis technology, analysis on the bioreactivity of PM10 from its microscopic characteristics was investigated and it seemed that there might two impossible reasons for the differences of bioreactivity： one was that finer particles which had relatively large surface area were the main parts in PM10 at Shangdianzi site, the number concentration in 0- 0.7 μm scale and the surface area in 0-1.0 μm scale were much higher than that of urban PM10. The other reason was that the main component of PM10 at urban site was coarser mineral particles, otherwise, the main type of particle in PM10 at Shangdianzi site was soot which was considered to be more bioreactive, accounting for as high as 58.8 %. Therefore, mass concentration is not the only index to assess the health effect of PM10; size distribution and particle type might play an important role in its bioreactivity.