北京东郊污灌区表层土壤微量元素的小尺度空间结构特征

岩溶山区表土中＾７Ｂｅ、＾１３７Ｃｓ、＾２２６Ｒａ和＾２２８Ｒａ地球化学相分配的实验研究表明，４种核素绝大部分存在于Ｆｅ－Ｍｎ氧化物，有机质及残渣相中。它们在表土的迁移过程中具微粒迁移性，能较好地随土粒般运，可作为土粒侵蚀或沉积的示踪剂。

SPATIAL STRUCTURES OF TRACE ELEMENT CONTENTS IN SEWAGE IRRIGATED SOIL AT THE EASTERN SUBURB OF BEIJING

The experimental results of geochemical speciation in the soils show that more than 85% of ⁷Be, ¹³⁷Cs, ²²⁶Cs and ²²⁸Cs are bound to organic matter, Fe Mn oxy hydroxide and residual fractions. They can be moved with soil particles and used as tracers for erosion and/or accumulation of soil particles. ⁷Be geochemical speciation in the soils agrees with its trace for seasonal particle transport. ¹³⁷Cs geochemical speciation is suitable to trace soil particle accumulation as well as sediment dating. ²²⁶Cs and ²²⁸Cs are combined in crystalline skeleton of clay minerals and mainly remain as a residue in the soils and very little is bound to the soluble, exchangeable, carbonate fractions. The differentials of ²²⁶Cs/ ²²⁸Cs activity ratios in different geochemical speciation in the soils can be used as a parameter to trace accumulation and/or erosion of soil particles.