石家庄地区大气细粒子增长特征初步研究

为研究石家庄地区大气细粒子的微物理特征,2010年5月在石家庄市气象局观测站,对大气颗粒物、NOx和SO2进行了外场观测.结果表明:石家庄地区粒径小于1.0μm的大气颗粒物中,0.01~0.1μm粒径范围的粒子所占比例高达89.3%,大气细粒子污染较为严重.0.01~0.02μm和0.02~0.1μm粒径范围的颗粒物具有大致相似的变化规律,且与0.1~1.0μm粒径范围的粒子数浓度变化趋势明显不同.通过对典型粒子增长事件的研究发现,0.01~0.02μm的粒子数浓度在上午8:00左右会急剧升高,并达到全天的最大值.其后,0.01~0.02μm的颗粒物粒径会不断增长,由于增长消耗,其数浓度会迅速下降,使得0.02~0.04μm的粒子数浓度在上午12:00前会迅速升高.通过对气象要素和污染气体的分析,发现在相对湿度较低、风速风向变化不大,太阳辐射增加的情况下,SO2气相成核参与颗粒物增长的可能性较大.

A preliminary study of the growth characteristics of ambient fine particles in Shijiazhuang

To better understand the microphysical characteristics of the ambient fine particles in Shijiazhuang, the atmospheric particles, nitrogen oxides (NOx) and sulphur dioxide (SO2) were measured at an observation station in Shijiazhuang meteorological bureau during May, 2010. The results showed that the ambient fine particle pollution was serious, especially the particle size in the range of 0.01~0.1μm, which accounting for about 89.3% of the total fine particles. The results of the diurnal variations of aerosol number concentrations suggested that the fine particles with the range of 0.01~0.02 μm and 0.02~0.1 μm had a similar diurnal cycle, however, the diurnal variation pattern of the particles ranged from 0.1 μm to 1.0 μm was quite different from them. According to the case study of the particle growth, the number concentrations of the particles with the range of 0.01~0.02μm increased rapidly at 08:00 in the morning, and then quickly reached its maximum value. Because of the continued growth of their diameter, the number concentrations of them decreased quickly. The size growth of these fine particles resulted in the fast increase of larger particles (0.02~0.04μm) before 12:00. In addition, the meteorological parameters and pollution gases was analyzed. The results indicated that the gaseous phase nucleation of SO2 was the most possible mechanism of the particle growth under the conditions of low relative humidity, small changes of wind speed/direction and the rising solar radiation.