放射性核素铌-95在环境中的迁移动力学研究

Due to their harmful nature to the ecological system and human health, radioactive contaminants emitted from nuclear power stations have already caused a lot of concerns among the general public. Previous studies on the radionuclides were mainly focused on caesium-137, strontium-90 and others. Our group has also carried out researchs on cobalt-60 and zirconium-95. However, there are very few reports on niobium-95, one of the main radionuclides in the effluent discharged by nuclear power stations and as a result, we know very little about its migration-transformation mechanism or its dynamics in the environment. This Project proposes to use isotope labeling technology to simulate pollutants and to study the dynamics of transportation, accumulation, diminishing and distribution of niobium-95 in the ecological system. Based on the compartment model theory in tracer kinetics, we will construct a mathematical model to computationally simulate the behaviors of niobium-95 in nature and to eventually reveal the rules and mechanisms of its migration and transformation. These data will lead to the first scientific evaluation of how niobium-95, discharged from our nuclear power stations, is transported and accumulated in the environment and crops. It is envisaged that our study will provide essential data and theoretical reasoning for our government to make relevant standards, laws and regulations which suit our nation's specific conditions. Furthermore, our experimental approaches of combining isotope labeling and computational modeling will provide novel methodologies to study the impacts of discharged radioactive materials on the environment and in the long run, help ensure the safety and sustainable development of our nuclear power industry.

核电站反应堆反应排放的放射性污染物对环境的危害已愈来愈引起公众的关切。国内外研究者主要集中在放射性核素铯-137、锶-90等核素的研究上。本课题组在前期也对钴-60、锆-95做了部分研究，但是，铌-95在生态环境中的迁移转化机理、动力学模型研究等，迄今国内外尚无报道。本课题采用模拟污染物的同位素示踪技术，研究核电站反应堆的主要放射性液态流出物如铌-95在生态环境中的迁移、消长、积累、分配和富集的动态过程及迁移转化机理。将从新的视觉研究，利用示踪动力学分室模型原理，通过计算机拟合建立铌-95在系统中行为规律的数学模型，从而为我国核电站运行过程中排出的铌-95在环境和作物中的输运和积累状况作出科学评定，为制定适合我国国情的有关标准、法规和准则提供基础数据和理论分析，并为核电站排放物的环境研究，为模拟污染物的同位素示踪技术在实验方法和对结果处理上提供新思路和新方法，确保我国核电安全并可持续发展。

核电站反应堆反应排放的放射性污染物对环境的危害已愈来愈引起公众的关切。本课题采用模拟污染物的同位素示踪技术，研究了95Nb在水生生态系中的迁移、消长、积累、分配和富集的动态，并应用库室模型确定了各体系的拟合方程。结果表明：95Nb进入水中后，在水生生态系中发生沉淀或与其他离子进行络合或被水生生物吸收或被吸附等形式在系统中迁移和转化，从而在系统各部分中分配和积累。在引入后的很短时间内，池水中95Nb的比活度迅速降至一定值后缓慢下降；底泥通过与95Nb进行离子交换，对95Nb凝聚物的吸附富集了大量的95Nb；水葫芦也可在短期内吸附大量的95Nb；鲫鱼和螺蛳对95Nb的吸附能力较弱，螺蛳肉中95Nb的富集率大于在壳中的富集率，95Nb在鱼体内的分布主要集中在内脏中。95Nb在系统各部分的量均受时间的影响。