Pu(Ⅳ)在高盐度花岗岩地下水中的形态分布特征  

Distribution and Chemical Species of Pu(Ⅳ) in High Salinity Groundwater from Granite Area

作　　者：周旭[1] 王煜[1] 李伟平[1] 张瑞荣[1] 韩小元[1] 党海军[1] ZHOU Xu WANG Yu LI Wei-ping ZHANG Rui-rong HAN Xiao-yuan DANG Hai-jun(Northwest Institute of Nuclear Technology, Xi＇ an 710024, China)

机构地区：[1]西北核技术研究所,陕西西安710024

出　　处：《原子能科学技术》2016年第11期1928-1936,共9页Atomic Energy Science and Technology

基　　金：国家自然科学基金资助项目(21477097)

摘　　要：将Pu(Ⅳ)加入罗布泊西北部花岗岩地区高盐度地下水中,并平衡1a,研究其在原位水中的形态分布特征,探讨其迁移行为。结果显示,示踪Pu(Ⅳ)在地下水中静置平衡1a后,其形态分布达到平衡;90%的Pu在较短时间(30d)内形成Pu假胶体而被容器壁吸附,溶液中的Pu主要为溶解态或小于3nm的可悬浮胶体,少量吸附于450nm以上的胶粒上;样品中溶解氧含量的增加及溶液pH值的升高可促进吸附在容器壁上的Pu胶体的解吸。胶体态Pu的结合形态分布从大到小依次为碳酸盐结合态(57.3%)、可氧化态(有机物结合态,21.7%)、可还原态(Fe-Mn氧化物态,11.2%)、残渣态(5.1%)、可交换态(4.7%);溶解态Pu的价态分布从大到小依次为Pu(Ⅳ)(71%)、Pu(Ⅴ)(24%)、Pu(Ⅵ)(5%)。分析以上结果可知:Pu(Ⅳ)在流速极慢(准静态)的含胶体的还原型高盐度花岗岩地下水中易形成Pu的假胶体,从而被岩壁吸附固定,少量溶解态Pu可随地下水的流动而迁移;地下水溶解氧含量的增加和pH值的升高有利于Pu从岩壁解吸,进而促进Pu的迁移。To explore the migration behavior of Pu in high salinity groundwater from granite area in Northwest of Lop Nor region,the distribution and chemical species of Pu（Ⅳ）were studied after Pu（Ⅳ）added into the groundwater and aged for one year.The results show that the distribution and chemical species of Pu reach the equilibrium after one year＇s aging in the groundwater.90% of spiked Pu is transformed into colloidal species in short-term（30d）and is adsorbed on the container wall.For the minority of Pu in water phase,most of it is dissolved species（or particles smaller than 3nm）while the left is colloidal species（particles larger than 450 nm）in solution.Pu isdesorbed from the wall of container,which can be attributed to the increase of the dissolved oxygen and/or the pH when the samples are shaked in the air.The chemical species of colloid-associated Pu（pseudo-colloid）is checked with sequential extraction method as carbonates（57.3%）,organic matter（21.7%）,Fe-Mn oxides（11.2%）,residual（5.1%）and exchangeable（4.7%）,while the oxidation state of dissolved Pu comes as Pu（Ⅳ）（71%）,Pu（Ⅴ）（24%）and Pu（Ⅵ）（5%）.The results of present work imply that a majority of Pu（Ⅳ）can be associated with colloid in high salinity groundwater（contained a mass of colloid and flowed very slowly）from granite area,and thus adsorbed on rock surface which can not transport through granite fracture.While the rest part,mainly dissolved in groundwater,may transport along with the water＇s flow.Pu on granite surface can be desorbed with the increase of the dissolved oxygen and/or the pH of the groundwater,and thus the migration of Pu will be enhanced.

关 键 词：Pu(Ⅳ) 形态分布 高盐度地下水 花岗岩 核素迁移 

分 类 号：X591[环境科学与工程—环境工程]