应用高分辨率场发射扫描电镜(FESEM)和图像分析技术研究了上海市区冬季(2005-01)大气可吸入颗粒物的形貌特征以及不同种类颗粒物的数量.粒度和等效体积.粒度分布.结果表明,上海市可吸入颗粒物中,矿物颗粒和烟尘集合体普遍存在,还有较多的未燃尽油滴残留颗粒;矿物颗粒有不规则状矿物颗粒、较圆滑矿物颗粒和规则长条状颗粒,烟尘集合体有链状、蓬松状等形态;矿物颗粒在数量和等效体积上平均分别占75%和64%,烟尘集合体在数量和等效体积上平均分别占25%和36%,矿物颗粒较多说明上海市冬季受扬尘影响较重;上海市区PM10的粒径主要分布在较细的范围内,其数量.粒度分布和体积.粒度分布随时间有明显的变化,白天矿物颗粒、烟尘集合体的数量分布的峰值分别出现在0.1—0.3、0.2—0.3μm;晚上2种矿物颗粒、烟尘集合体的数量分布的峰值分别出现在0.3—0.5μm、0.4—0.6μm,呈现晚上颗粒物粒径较大的倾向.
High resolution field emission scanning electron microcopy (FESEM) and image analysis (IA) were used to study individual particle morphology, and the number-size and volume-size distributions of the PM10 collected in Shanghai during winter (January 2005 ). The results showed that the mineral particles and soot aggregates were ubiquitous in PM10 of Shanghai, and some residual droplets of fuel oil were also seen. The mineral particles included irregular, circular and regular morphological types. The soot aggregates had chain and fluffy types. The mineral particles accounted for 75% and 64% by number and by volume, while the soot aggregates only took 25% and 36%, respectively. The high proportion of mineral particles implied that serious blown dust influenced the Shanghai air in winter. The fine particles were prevailing in the Shanghai PM10. There were distinct temporal variations in the number-size distribution and volume-size distribution. The number-size distribution of the mineral particles and soot aggregates of the daytime PM10 had peaks at 0.1 - 0.3 μm and 0.2 - 0.3 μm, respectively, while, the number-size distributions of two types of particles in the nighttime showed peaks at 0.3 - 0.5 μm and 0.4 - 0.6 μm, respectively. This demonstrated that the particles in the nighttime were bigger than those in the daytime.