气载流出物中C-14和I-129在典型植物体中的分布、转化和迁移行为研究

气载流出物中含有的C-14和I-129是核设施放射性安全评估中重要的两个核素，而开展C-14和I-129在植物体内的动态转移等相关行为研究，对全面评价其环境风险十分关键，契合我国始终坚持的安全第一的核安全战略。本项目拟选择水稻、青菜等作为研究对象，借助元素成像等现代分析仪器，首先研究不同形态C-14和I-129在植物各部位的平衡过程和界面传输过程，揭示其在作物体内的分布、累积、转化及动态迁移规律。其次改变C-14和I-129的吸收途径、环境因素等，系统研究条件变化对其在植物体内分布、转化和动态迁移的影响及机制，发展和构建适用于我国核素排放特征的动态迁移模型。同时还将研究C-14和I-129对植物的毒性效应及毒性效应对核素动态迁移规律的影响，进一步对所构建的动态迁移模型进行修正，最终形成能更好描述、预测气载流出物中C-14和I-129生态风险的模型，为评价其环境风险提供关键科学基础。

The emerging release of nuclides into atmosphere leads to the their widely distribution in environment, followed by threatening the ecosystem and even human health. As producer in ecosystem, plant serves as the main mediator for the entrance of nuclides into food web and possesses essential role in the global cycle of nuclides. C-14 and I-129, which includes in airborne radioactive effluence, are two of the most important nuclides in safety assessment of nuclear facilities. Thus, the study on the dynamics of bioaccumulation and transfer of airborne nuclides in plant, as well as the establishing of well describable mathematical models for the dynamics, is critical in prediction on the safe threshold for the effluence of nuclear facilities and its environment risk assessment. In this project, the bioaccumulation distribution, transformation and transfer dynamics of typical nuclides C-14 and I-129 in airborne effluence to plant are systematically investigated. Typical crops, including rice, cabbage and potato, are chosen to be exposed in C-14 and I-129. The equilibrium and Interface transfer of them in each tissues of plants are analyzed using radioactive quantification and modern analysis techniques such as elemental imaging, which indicate the uptake pathway, transfer dynamics, distribution process and retention of various types of C-14 and I-129 in plant tissues. The key factors that may influence the transfer dynamics of C-14 and I-129 to plant and their effect mechanisms are clarified by controlling the experiment parameters such as transfer pathways, environment condition and plant characteristics. Based on the certain key effective factors and their relative contribution, mathematical models are constructed and developed for the suitable illustration on the typical transfer dynamics of nuclides in our country. The toxic effects of C-14 and I-129 to plant tissues and corresponding mechanisms are further explored to clarify the inner connection between the internal exposure dose and effects. The toxic effects are served as assessment objects to construct new model suitable to predict the plant exposure risk of C-14 and I-129. The toxic effects are served as reference objects to modify and reweigh the parameters in constructed models to develop a model that is suitable to illustrate and predict their environment risks to the whole food chain. These results and obtained developed models will provide scientific information for the prediction of transfer dynamics to plant and accurate environmental risk assessment of the nuclides in airborne effluence.