Characterization and Biological Effect of Long-Lived Radionuclides in Environmental and Ecological System

1 .长寿命放射性核素在环境中的物理化学特征和行为(1)采用新方法测定了空气粉尘中放射性核素的粒径分布。(2)采用电感耦合等离子体质谱法（ICP-MS）测定低水平长寿命放射性核素浓度。(3)制备了二硫代氨基甲酸酯-几丁质（dtc -甲壳素），用dtc -几丁质分离了Tc和Ru。(4)确定了太平洋中Pu和U的特征。因此，Pu的物理形态与U相似，而Pu的化学性质与U不同，与Th.II相似。(5)在实验室条件下，研究了放射性钴与海岸沙质沉积物相互作用的化学转化，以及贻贝（Mytillissepta virgatus）对离子和有机形式放射性钴的吸收和消除，以及放射性钴在养殖海水中的吸附行为。(6)研究了海洋生物对特定元素的特殊生物浓度，阐明了长寿命放射性核素在海洋生态系统中的行为。(7)测定了碘态放射性碘和甲基碘在土壤和大气中向作物的转移因子。这些结果表明，甲基碘对植物组织的渗透性明显大于碘。(8)在所分析的日本人组织中，骨中Po-210和Pb-210的浓度最高。对吸烟对肺部的吸收剂量率进行了估计，对于标准模型吸烟者，香烟中Po-210引起的肺癌死亡率风险为9x10^<-6>。

I. Physical and Chemical characterization, and behavior of long-lived radionuclides in the environment (1) Particle size distribution of radonuclides in air-borne dust by newly developed method was measured. (2) Concentration of low-level long-lived radionuclides was determined by Inductively Coupled Plasma-mass spectrometry (ICP-MS). (3) Dithiocarbamate-Chitin (DTC-chitin) was prepared and Tc and Ru was separated by using the DTC-chitin. (4) In the pacific ocean characterization of Pu and U was determined. Consequently, the physical form of Pu was similar to U while chemical property of Pu was differed from U and resembled Th.II. Uptake of environmental radionuclides and effect (5) The chemical transformation based on the interaction of radiocobalt with coastal sandy sadiment and the uptake and elimination of the radiocobalt in both ionic and organic forms by mussel, Mytillissepta virgatus, as well as adsorptie behavior of the radiocobalt in the rearing seawater were studied under laboratory conditions. (6) Peculiar biological concentration of specific element by marine organisms was examined to clarify the behavior of long-lived radionuclides in marine ecosystem. (7) Transfer factors of the radioiodine in iodine form and methyliodide of soil-to-crops and atmosphere-to-crops were determined. These results indicate that the permeability into the plant tissues of methyliodide is significantly larger than that of iodine.III. Characterization and assessment of dose contribution (8) Among the Japanese tissues analyzed, the highest concentrations of Po-210 and Pb-210 were observed in bone. The absorbed dose rate to the lungs due to smoking was estimate and the risk mortality from lung cancer caused by Po-210 in cigarettes is 9x10^<-6> for the Standard Model Smoker.