氚水在大豆土壤系统中的迁移与分布

采用模拟污染物的同位素示踪技术研究氚水在大豆-土壤模拟生态系统中的迁移、分布规律.通过为期50d的模拟试验,测定了植物和土壤样品中2种形态氚(自由水氚和结合态氚)的比活度.结果表明:引入土壤中的氚水,不仅在系统各分室间转移和分配,而且迅速向系统外散逸;氚水中的氚以自由水氚和结合态氚形态存在于大豆植株和土壤中;大豆植株中的自由水氚比活度于6h时即达最大值(根19.4Bq·g^-1;茎叶12.3Bq·g^-1),随后便逐渐下降,而结合态氚呈缓慢增加;大豆根中的总氚比活度开始时高于茎叶中的比活度,而后趋于平衡,表层土中2种形态氚基本呈逐渐下降.运用示踪动力学分室模型原理对实验数据拟合得:土壤中的比活度C_s=88.37e^-11.847t+7.38e^-0030t;大豆植株中的比活度C_b=10.30(e^-0.030t-e^-11.847t).

The Transference and Distribution of Tritium Water in the Soybean-Soil System

The isotope trace techniques of simulation contamination were applied to explore the rule of transference and distribution of tritium water in a simulated soybeam soil ecosystem.The activity ratio of two forms of tritium in plant and soil sample were measured by 50 days simulation experiment.The results showed that when tritium water was entered the soil,it not only was transferred to other compartments in the system,but also vaporized into atmosphere rapidly.Both free water tritium and bound tritium were found in the soybean and the soil.The activity ratio of free water tritium reduced after reaching the maximum (19.4Bq·g^-1 in root,12.3Bq·q^-1 in stem and leaf) at 6th hour in the soybean.The bound tritium increased slowly.The activity ratio of total tritium in soybean root was upper than those in stem and leaf in the earlier stage,they reach equipoise each other in the later stage.The activity ratio of two tritium in the surface soil reduced continuously.The compartment model of tracer kinetic was applied to imitate the experimental data.The activity ratio of soil C_s=88.37e^-11.847t+7.38e^-0.030t and the activity ratio of soybean C_b=10.30(e^-0.030t-e^-11.847t) were gained.