降尘收集方法对沙尘理化性质的影响及环境意义

利用建立在腾格里沙漠东南缘的中国科学院风沙观测场内收集的降尘,分析了不同降尘收集方法收集的降尘粒度、化学元素含量、富集因子、硅铝率和硅铝铁率,旨在优化干旱区降尘收集方法、确定我国的沙尘源区.降尘物质的微量元素Ba的含量最大,可达255~474μg/g, Nd的含量为0.3~9.6μg/g;常量元素SiO2的含量最大,79.30%, MgO含量最小,0.98%.微量元素的富集因子值在0~3之间,但常量元素差异较大.结果表明,减速法和湿法收集的降尘从粒度分布、化学元素含量、富集因子、硅铝率和硅铝铁率等方面均具有一致性.平均粒径湿法最细(Φ值2.84),干法最粗(Φ值2.46).因此,减速法能够作为代替湿法在干旱区进行收集降尘的方法.同时,由降尘的地球化学性质可知,西北干旱区沙漠是我国的主要沙尘源区之一.

Effect of dust deposition collection method on dust physicochemical properties and its environmental significance.

Using dust material collected in the Shapotou Aeolian Experiment Site in the southeastern part of the Tengger Desert, the dust particle sizes, chemical element composition, chemical enrichment factor, and Si/Al and Si/Al Fe ratios were analyzed. The aims of the study was to provide optimizational dust collection methods and confirm the dust sources. The content of the Ba was largest and was about 255~474μg/g, Nd was smallest and was about 0.3~9.6μg/g; the content of the SiO2 was largest and was about 79.30%, and MgO was smallest and was 0.98%. The enrichment factors was between 0 and 3. The results indicated that the reduction velocity method and wet method caused similar changes to all studied parameters. The mean grain size was finest (Φ was 2.84) for the wet method and coarsest (Φ was 2.46) for the dry method. The reduction velocity method could be used to substitute for wet dust collection method for dust collection in dry regions. Based on chemical characteristics of the dust material, desert regions in northwestern China were the main dust sources.