粘土矿物比率对沙尘源区的指示

为了探讨中国北方沙尘源区矿物组成特征并建立沙尘气溶胶的矿物示踪指标,在亚太地区气溶胶特征实验(ACE-Asia)期间对新疆阿克苏、甘肃敦煌、陕西榆林和内蒙古通辽沙尘气溶胶的矿物组成进行了研究.结果显示,中国主要沙尘源区沙尘气溶胶中高岭石与绿泥石的比率存在明显差异,西部沙尘源区(以阿克苏站点为代表)高岭石与绿泥石的比值较小(平均值为0.3),而北部沙尘源区(以榆林站点为代表)高岭石与绿泥石的比值相对较高(平均值为0.7).沉降区长武尘暴样品的粘土矿物比率和气团轨迹分析证实,在区域范围,高岭石与绿泥石的比值为较好的沙尘源区矿物示踪指标.而亚洲沙尘与撒哈拉沙尘的对比显示,高岭石与绿泥石的比值在全球范围有着沙尘源区指示的意义.

Clay Ratio as a Tracer to Assess the Origin of Soil-Derived Dust

The objectives of this research are to characterise the mineralogy of soil-derived dust in Northern China and to set up the mineralogical signature to trace their origin. Mineral composition of aerosol particles is investigated at five sites (Aksu, Dunhuang, Yulin, Tongliao and Changwu) during the intensive field campaign period of ACE-Asia. The results show that the Kaolinite (K) to Chlorite (C) ratio is sensitive to the regional origin of Asian dust. Western source areas (represent by Aksu) displayed the lowest K/C ratio of 0.3 (in average), while it was found that to increase up to 0.70 (in average) as moving towards north source areas (represent by Yulin). By studying transported dust in a depositional area representative of the Chinese Loess Plateau, the usefulness of the K/C ratio to retrieve the origin of the dust by associating it with back air-mass trajectories is checked. Compared the mineralogical data between Asian dust and Sahara dust, it is shown that K/C ratio is also a good signature to identify the source areas on the global scale.