黄土风化成土过程中主要元素迁移序列

主要研究了渭南黄土剖面中主要化学组分的分布特征、影响因素以及它们在风化成土过程中的迁移富集规律。结果表明：（1）在剖面中随着黄土与古土壤层的交替叠复，各组分含量由低-高或由高-低呈周期性变化。（2）碳酸盐含量的剧烈变化是影响黄土元素分布特征极为重要的因素，古土壤中一些组分的含量增高，主要是碳酸盐被强烈淋滤造成的相对富集。（3）在黄土风化成土过程中，CaCQ3、SiQ2、FeO、MgO、K2O、Na2O等本身的地球化学行为以迁移为主，而Al2O3、Fe2O3、TiO2等均以淀积为主。它们在黄土中的迁移能力有如下顺序：CaCO3＞FeO＞MgO＞Na2O＞K2O＞SiO2＞Al2O3＞TiO2＞Fe2O3。（4）除碳酸盐外，黄土风化成土过程中铁的变化比其它组分都明显，表现为价态以及形态的转化。铁的转化主要为就地完成．本身没有发生明显迁移。

THE MIGRATION SERIES OF MAJOR ELEMENTS DURING LOESS PEDOGENESIS

Loess samples from the Weinan loess section were studied for chemical composition and major ele-ment distribution. The results show that: 1) the distributions of all the constituents exhibit periodicvariations with the alternative superimposition of loess and paleosol layers in the section; 2) violentleaching of carbonates in paleosol layers would strongly affect the distributions of other constituents inthe section, which resulted in the relative enrichment of some elements in the paleosol; 3) during loesspedogenesis the constituents CaCO3, SiO2, FeO, MgO, K2O, and Na2O tend to migrate, butAl2O3, Fe2O3 and TiO2 to deposit. Their migration series in the loess is: CaCO3 > FeO> MgO > Na2O> K2O > SiO2 >Al2O3 > TiO2 > Fe2O3; and 4) during the pedogenic process iron experienced no obvi-ous migration, but remarkable changes in valence and form. From this view point, iron varied moreremarkably than the other elements except for carbonate, as shown by its in-situ changes in valenceand form.