乌鲁木齐霾天气PM_(10)单颗粒物理化学特征

Physical and Chemical Characteristics of Individual Particle during a Typical Haze Episode in Urumqi,Xinjian,China

为了解乌鲁木齐冬季污染天气形成过程中大气颗粒物化学组分的变化,探讨霾天气快速形成的主要原因,应用扫描电镜/X射线能谱仪(SEM/EDX)对2013年2月乌鲁木齐东南郊一次典型霾天和正常天气所采集的大气颗粒物(PM10)样品进行了微观形貌和化学组成的对比分析。结果表明:伴随着霾形成过程细粒子浓度呈现急剧上升趋势,PM1.0/PM10比值高达0.77。SEM/EDX观测显示,霾天形成前后,PM10的形态结构和元素组成存在较明显的差异,霾天规则的石膏颗粒占规则颗粒的71.1%,明显高于正常天气,表明大气颗粒物的硫化现象比较普遍,大量硅铝酸盐飞灰说明采样点周边有较明显的燃煤源输送;二次无机颗粒组成主要为硫酸盐颗粒,由正常天气的16.1%增加到24.6%,高浓度硫酸盐与乌鲁木齐东南郊此次霾形成有密切的联系。

In order to understand the chemical composition of atmospheric particulates during the winter haze espsode in Urumqi,and to explore the causes of haze formation,the scanning electron microscopy and energy dispersive X-ray spectroscopy(SEM/EDX)were used to study the chemical composition and microscopic morphology of aerosol PM10 samples collected during the typical haze and no-haze episodes in February 2013.The results indicated that the fine particle concentration showed a sharp rise in the haze formation process,and the PM1.0/PM10 ratio could reach 0.77.There exists significant difference in chemical composition and microscopic morphology of PM10 between haze and no-haze episodes.Regular gypsum particles could account for 71.1%in haze weather,apercentage obviously higher than that in no-haze episode.This fact showed that the surface sulfuration of aerosol particles was extremely severe,and the large amount of aluminosilicate particles in fly ash came from coal combustion pollution.As the main component of secondary inorganic particles,sulfate particles accounted for 24.6%in haze episode,but it only accounted for 16.1%on no-haze day.Sulfate was the primary factor contributing to this heavy haze formation in Urumqi.