黄土中矿物元素的淋溶释放研究

选取我国西北地区广泛分布的黄土进行模拟降水淋溶实验,研究了在动态淋溶系统中盐基离子和ＳｉＯ２、Ｃｌ－等黄土主要组份的释放规律及淋出液的ｐＨ值变化特点,在此基础上对黄土中各矿物元素的淋溶释放机制进行了探讨。结果表明,黄土中的Ｎａ＋、Ｃａ２＋、Ｍｇ２＋、Ｃｌ－主要通过快速的无机盐溶解过程淋失,而Ｋ＋、ＳｉＯ２的淋溶释放则与缓慢的硅酸盐矿物风化有关。粗略的通量计算结果显示,在黄河流域,降水淋溶侵蚀作用每年可从黄土中淋失盐基离子４０．７ × １０９ｍｏｌ,占黄河溶解态物质入海通量的近２０%。

Releasing of major elements from loess leached by rain

ased on a dynamic experiment design, loess sampled from northwestern China was leached by simulated rain of a pH value of 5.6. The characteristic and mechanisms of cations, Si and Cl- release and pH value of the leachate were investigated. The results showed that Na+, Ca2+, Mg2+ and Cl- were leached mainly through fast congruent dissolution of inorganic salts and the release of K+ and Si was controlled by slow incongruent weathering of silicates. The rough evaluation of leaching flux of these major elements indicated that rain leaching of loess played an important role in the transportation of major chemical elements in the Yellow River.