北京及其北部地区大气自然降尘矿物组成特征

Mineral Composition Characteristics of Natural Atmospheric Dusts in Beijing and the Northern Areas to Beijing

为研究北京地区大气自然降尘的矿物组成特征及其时空变化规律,采用XRD分析了不同季节收集的大气降尘样品。结果表明,大气降尘主要矿物为石英,平均含量为83.19%,长石以斜长石为主;降尘中的碳酸盐类矿物主要是方解石和白云石,它们在降尘中的含量接近其在北方黄土中的含量;降尘中粘土矿物的含量较少,为1.64%~5.88%,其中有较多的高岭石,反映了研究区半湿润、较温暖的环境。聚类分析表明本区降尘按矿物组成特征可分为城市和郊区两组。与大风天气少的月份相比,大风天气频繁的月份降尘中的长石等矿物含量相对较高,而粘土矿物含量相对较低。

A batch of natural atmospheric dust samples collected in Beijing and the northern regions to Beijing in the different seasons were analyzed by X-ray power diffraction to study their mineral composition characteristics and their temporal-spatial distribution.The results showed that Quartz is the main mineral with an average content of 83.19% and that the main Feldspar is Plagioclase,indicating the weakly weathering process of the dust source region.Calcite and dolomite are the main carbonate minerals,representing comparability with the Chinese loess.The dust contains a small amount of clay minerals,1.64%-5.88% of the total mineral mass.Kaolinite is the main content of the clay mineral reflects the semi——wetness,relatively mildness surface environment of the study areas.Clustering analysis indicated that the sampling sites can be classified into two groups（urban and rural）according to the mineral composition characteristics.The dust samples collected in windy months possess relatively higher amount of clay and lower amount of Feldspar than those collected windless months.