中国黄土地区土壤中天然放射性元素的生物地球化学

本文叙述了我国黄土地区主要类型土壤中天然放射性元素的含量水平、迁移积聚和剖面分布情况。研究结果表明，本地区土壤放射性元素的含量、比值和离散程度均接近其黄土母质，但各土类间仍表现出一定的分异，在弱碱性的土壤环境里，以（ＵＯ２）＾２＋存在的铀比较活跃。碳酸盐能促使铀的淋滤，而有机质的存在却有利于铀的积聚。钍和镭集中积蓄在富含粘粒的土层中，但在林地土壤中钍有淋移的迹象。从各核素的剖面分布看，土壤在发育过

BIOGEOCHEMISTRY OF NATURAL RADIOACTIVE ELEMENTS IN SOILS OF LOESS REGION IN CHINA

The contents,migration and profile distrjbution of natural radioactive elements in main groups of soils of loessial region are described in this paper.The results showed that contents,ratios and variance of radioactive elements in the soils were approaching to those in loessial parent materials.But certain variations were found among the soil groups,(gray-drab forest soil>stratified old manured loessial soil> drak loessial soil) sierozem>cultivated loessial soil>> aeolian sand soil).In alkalescent-oxidative condition of soil,uranium in the form of (UO₂)²⁺ was more active.Carbonate precipitated the luvic migration of U and organic matter fapoured the accumulation of U.Th and Ra accumulated in the soil layers rich in clay particle,but leaching trace of Th existed in the forest soils.In view of profile distribution,biological accumulation of radioactive elements exceeded leaching in the soil forming process.Under different la}iid utilization conditions,anthropic transfer of material intensified differentiation of the content and distribution of radioactive elements in soils.