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

I.长寿命放射性核素的物理化学特性及其在环境中的行为（1）采用新开发的方法测量了大气粉尘中氡的粒径分布。(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的浓度。(3)制备了二硫代氨基甲酸酯-甲壳素（DTC-甲壳素），并将其用于分离Tc和Ru。(4)在太平洋中，确定了钚和铀的特征。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相似。（5）在实验室条件下，研究了放射性钴与沿岸桑迪沉积物相互作用的化学转化、放射性钴在贻贝体内的吸收和消除，以及放射性钴在养殖海水中的吸附行为。(6)为了解长寿命放射性核素在海洋生态系统中的行为，研究了海洋生物对特定元素的特殊生物富集。(7)测定了土壤和大气中碘形态和碘甲烷向农作物和农作物的转移因子。这些结果表明，碘甲烷进入植物组织的渗透性明显大于碘。剂量贡献的表征和评估（8）在分析的日本组织中，在骨骼中观察到Po-210和Pb-210的最高浓度。估算了吸烟引起的肺吸收剂量率，标准吸烟者中香烟中Po-210引起肺癌的危险死亡率为9 × 10 - 4<-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.