【摘要】 为研究兰州市2006年3月31日沙尘暴期间及之前大气PM10中的矿物学特征,运用场发射扫描电镜和带能谱的扫描电镜识别和统计了PM10中单个颗粒的微观形貌特征和矿物组成。结果表明,沙尘暴期间PM10的质量浓度是一个突增渐降的过程,沙尘暴到来时,PM10的质量浓度在短时间内增至约1500μg/m3,然后随着沙尘暴的消退逐渐降低,在较长时间内保持较高的浓度值,期间主要为矿物颗粒;沙尘暴之前,PM10的质量浓度普遍高于国家二级标准(150μg/m3),最高可达500μg/m3,主要颗粒类型有燃煤飞灰、烟尘集合体和少量的矿物颗粒。单颗粒矿物分析表明,沙尘暴之前的非沙尘暴期,单个矿物颗粒的数量百分比从大到小依次为方解石、石英、伊利石、绿泥石、伊/蒙混层、钙长石、钠长石、钾长石、高岭石和石膏等,沙尘暴期间,矿物颗粒中伊利石和绿泥石的数量百分比明显增加,而方解石含量明显减少。更多还原

【Abstract】 In order to study the mineralogical characteristics of inhalable particulate matter(PM10) collected before and during the dust storm occurred on March 31,2006,in Lanzhou city,Field Emission Scanning Electron Microscopy(FESEM) and scanning electron microscope with energy dispersive X-ray(SEM/EDX) were applied to investigate the morphological characteristics and mineral compositions of individual particle in PM10.The results showed that during the peak time of the dust storm,mass concentration of PM10 increased to approximately 1500 μg/m3 in a short time,then decreased gradually and kept a high level for a long time as dust storm was weakening,and most of PM10 were minerals.Before the dust storm,mass concentrations of PM10 during sampling time(Max,500 μg/m3),were generally higher than the national standardⅡ(150 μg/m3),and the particle types of PM10 were dominated by coal fly ash,soot aggregates,with only a small amount of minerals.The analysis of the individual mineral particles by SEM/EDX indicated that the minerals in non-dust storm particles were mainly consisted of calcite,quartz,illite,chorite,illite/smectite mixed layers,anorthite,albite,feldspar,kaolinite and gypsum in a descending order.In contrast,minerals in airborne particles collected during the dust storm episode were characterized by higher proportion of illite and chlorite and lower proportion of calcite.This is due to large amounts of dust particles which were carried in from dust source areas.更多还原