成都市近地表大气尘的矿物学特征及其环境指示意义

通过对成都市近地表大气尘X射线衍射、电镜扫描分析等研究显示:其主要由石英、长石、伊利石、绿泥石、方解石、石膏等矿物组成;就其形状看有致密的不规则粒状、片状单矿物、不规则粒状聚合体、浑圆形球状飘珠、聚合体放大观察可见片状的粘土矿物和细小的粒状单矿物,偶见藻类;矿物形貌特征及矿物组成空间分布特征的研究显示:球形状飘珠及伊利石、绿泥石、石膏的空间分布特征与工业布局和表层土壤的pH值密切相关,成都市近地表大气尘主要为地表扬尘和工业烟尘的混合物;与土壤的矿物组成比较可见,近地表大气尘重金属污染除土壤贡献外,还有其他污染贡献;石膏在本次研究中平均含量高达8.2%,推测可能成为成都市往年燃煤量大而无明显酸雨现象的原因之一。

THE MINERALOGY CHARACTER OF THE AIR DUST NEAR THE GROUND IN CHENGDU AND ITS ENVIRONMENTAL INDICATION SIGNIFICANCE

Components of air dust near the ground in Chengdu City were studied by XFR and SEM and the results show that the mineral composition include quartz,feldspar,illite,chlorite,calcite and gypsum etc.The Scanning electron microscopy shows that the dust shape composed of compact irregular grain,sheet like mineral,irregular grain aggregate and sphericity vitreous.Magnifying the aggregate,sheet clay mineral and little simple mineral and algae can be seen occasionally.The spatial distribution of sphericity vitreous,illite,chlorite and gypsum is associated with industry layout and soil pH,and mainly composed of dust and industrial soot.Comparison of the composition of mineral with that of soil indicates that it mainly come from soil also.This study shows that the gypsum accounts for 8.2 percent in the air dust near the ground.It is maybe resulted from the large amount of coal burning and it is one of the reasons for the lack of acid rain in the Chengdu City.