岩溶山区表土中~7Be、~(137)Cs、~(226)Ra和~(228)Ra的地球化学相分配及其侵蚀示踪意义

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（８５％以上）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．但其微粒示踪类型又各具特征：７Ｂｅ的化学形态与其季节性微粒迁移示踪一致；１３７Ｃｓ的化学形态适用于示踪土粒累计性迁移和沉积计年；２２６Ｒａ和２２８Ｒａ存在于粘土矿物结晶骨架中，在表土中主要以残渣相存在，由矿物化学风化作用而转入可溶解、可交换及碳酸盐结合相的比例很小，二者比活度的形态变化分异具有很好的侵蚀堆积示踪价值．

GEOCHEMICAL SPECIATION OF 7Be, 137 Cs, 226 Ra and 228 Ra IN SOILS OF THE KARST REGION, SOUTHWESTERN CHINA AND THEIR EROSION TRACE

The experimental results of geochemical speciation in the soils show that more than 85% of 7Be, 137 Cs, 226 Ra and 228 Ra 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. 137 Cs geochemical speciation is suitable to trace soil particle accumulation as well as sediment dating. 226 Ra and 228 Ra 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 226 Ra/ 228 Ra activity ratios in different geochemical speciation in the soils can be used as a parameter to trace accumulation and/or erosion of soil particles.