暖温带地理景观中土壤硒的分异特征

本文按垂直自然带谱研究了暖温带地理景观中山地草旬土、山地棕壤、山地淋溶褐土和潮土中硒的分异特征。结果表明：（1）硒在土剖面上的分异，除受生物富集的影响外，淋溶和粘人作用强烈地制约着硒在剖面上的迁移；（2）不同机械组分中的硒含量以粘粒中最高，呈明显的粘粒＞细粉粒＞中粉粒＞砂粒序列。因此，成土过程中，不同机械组分以及次生或们生矿物和垂直运动和自然分选作用对土壤硒的地理分异具有非常重要的作用。（3）易于淋溶失的有机态或钙结合的硒对所研究的土壤表层硒的贡献都大于50％。提出淋溶作用是我国低硒带形成的主要外营力。

THE DIFFERENTIATION CHARACTERISTICS OF SOIL SEL-ENIUM IN WARM-TEMPERATE GEOGRAPHIC LANDS-CAPE

The selenium differentiation in mountain meadow soil, mountain brown soil, mountain leached drab soil and cultivated fluviogenic soil in warm-temperated geographic landscape has been studied according to vertical natural zonality. The results show as follows: 1. Besides affected by the biological enrichment, the selenium distribution in soil profile is greatly affected by the eluviation and granulitization. 2. The selenium content in clay is the highest, which gradually decreases with series of clay> fine powder > middle powder > sand. In the soil-forming process, the soil mechanical composition, the vertical movement and natural gradation of secondary and epigenetic mi-nerals play important roles in the soil selenium differentiation. 3. The contribution rate of easy leaching selenium associated with organic and calcium is more than 50 percent in the studied surface soils. This shows that eluviation is the dominated exogenic force in the forming of low selenium belt of China.