蒙脱土对Cs在土壤-大豆系统中迁移的影响及生物有效性研究

目的 放射性Cs是目前土壤放射性污染的主要污染物。本文探讨蒙脱土对Cs在土壤-大豆系统中迁移的影响，为土壤放射性Cs污染修复和生物有效性评价提供一定理论依据。方法 文章以温室盆栽大豆Glycine max（L.） Merr.]为实验研究对象，在栽培土壤中添加不同比例的蒙脱土，并对3种浸提剂所提取植物根系直接接触土壤、根际土壤和非根际土壤中可交换态Cs的生物有效性含量进行比较分析。结果 土壤中添加0.5%蒙脱土可显著降低Cs向大豆植物体的迁移量，此时，大豆根、茎和叶的富集率（CR）分别下降至对照的51%、76%和66%。浸提实验结果显示提取Cs的含量由多至少所用浸提剂为：NH₄OAc > HAc > MgCl₂，NH₄OAc所提取Cs的可交换态含量是另两种浸提剂的10倍，使用HAc提取土壤可交换态的Cs与大豆器官中Cs含量呈正相关关系。结论 经比较分析土壤中添加0.5%的蒙脱土可作为土壤修复Cs污染的参考量，HAc可作为评价土壤中Cs生物有效性的参考浸提剂。

Effect of montmorillonite on the transfer of cesium in soil-soybean system and analysis of bioavailability

Objective Radioactive cesium (Cs) was a mian cause of soil radioactive contamination. This study aimed at exploring the effect of montmorillonite on the transfer of cesium in soil-soybean system to provide theoretical basis for the remediation and evaluate bioavailability. Methods Varied montmorillonite were added to the Cs contaminated soil and pot experiments were conducted on soybeanGlycine max (L.) Merr.] uptake Cs in a green house. The bioavailability of Cs in roots directly contact soil, rhizosphere soil and non rhizosphere soil were analyzed with three different extractants. Results Adding 0.5% montmorillonite could significantly decrease Cs transportation, and the concentration ratio (CR) of roots, stems and leaves were 51%、76% and 66% respectively. The content of extracted Cs was in the order:NH₄OAc > HAc > MgCl₂. The exchangeable content extracted by NH₄OAc was 10 times of the other two. There were positive correlation between exchangeable phrase Cs content by HAc and the Cs content in soybean organs. Conclusion By comparison analysis, 0.5% montmorillonite in experiment soil can be used as an optimal choice for soil remediation of Cs pollution. Meanwhile, HAc can be used as a reference to evaluate the bioavailability of Cs in soil.