摘要
我国表层土壤中存在的钚主要来自于20世纪中后叶大气层核试验之后的全球沉降。本研究以土壤中现存的钚为研究对象,利用加速器质谱(AMS)和电感耦合等离子体质谱(ICP-MS)对环境中痕量水平钚同位素精准测量技术,在我国部分典型地区进行了现场土壤纵向分层采样和实验室测量。在此基础之上,将对流-弥散方程在单次瞬时输入情况下的解与我国不同地区土壤柱中钚核素的垂直分布数据进行了拟合,得到新疆、湖北、贵州、重庆、甘肃土壤中钚核素的表观对流系数为0.046~0.163 cm/a,表观扩散系数为0.058~0.339 cm2/a,土壤中239+240Pu浓度峰的迁移速率为0.063~0.187 cm/a。实测结果表明,钚同位素在土壤中的迁移速率与土壤有机质含量有明确的负相关关系。
The ultra-trace level of Pu （plutonium） isotopes in Chinese surface soil are mainly resulted from global fallout following the world-wide atmospheric nuclear tests last century. The vertical migration behaviors of Pu in soil were studied by field sampling and laboratory measurements using AMS （Accelerator Mass Spectrometry） and ICP - MS （Inductively Coupled Plasma Mass Spectrometry）. Subsequently by fitting the vertical distribution of ^239＋240pu with the solution of convectiondispersion equation in single pulse condition, the apparent convection coefficient V in Chinese soils was found to be 0. 046-0. 163 cm/a, the apparent diffusion coefficient D ranged from 0. 058 to O. 339 cm^2/a and the migration velocity of ^239＋240pu concentration peak in soils of different areas from 0. 063 to 0. 187 cm/a. Based on these, the predicted ^239＋240pu concentration peak would remain in top 10 cm of the surface soil in Chongqing province after 200 years＇ migration. The results indicated that the organic matter content of soil would be a key factor influencing the migration behavior of Pu. Besides, other soil parameters such as porosity, soil particle size, cation exchange capacity etc. tend to have influences on the migration velocity of Pu in soils.
出处
《辐射防护》
CAS
CSCD
北大核心
2017年第1期1-7,共7页
Radiation Protection
基金
国家自然科学基金资助项目(No.11275015)
