镅在北山地下水中赋存形态及溶解度分析

辐射防护 ›› 2016, Vol. 36 ›› Issue (1): 40-46.

镅在北山地下水中赋存形态及溶解度分析

郭辉¹, 康明亮^1,2, 陈万良¹, 龙俊辰¹, 赵准¹

1.中山大学中法核工程与技术学院,广东珠海 519082;
2.中国科学院广州地球化学研究所矿物学与成矿学重点实验室,广州 510640

收稿日期:2014-12-11 出版日期:2016-01-20 发布日期:2021-11-12
通讯作者: 康明亮。E-mail: kangml3@mail.sysu.edu.cn
作者简介:郭辉(1991—),男,中山大学中法核工程与技术学院核能与核技术工程专业在读硕士研究生,E-mail: 378132038@qq.com
基金资助:
国家自然科学基金(No. 41403075)及中山大学青年教师培育项目(No. 45000-31610011)资助。

Speciation and solubility of americium in Beishan groundwater

Guo Hui¹, Kang Mingliang^1,2, Chen Wanliang¹, Long Junchen¹, Zhao Zhun¹

1. Sino-French Institute of Nuclear Engineering and Technology, Sun Yat-Sen University, Guangdong Zhuhai 519082;
2. CAS Key Laboratory of Mineralogy and Metallogeny, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640

Received:2014-12-11 Online:2016-01-20 Published:2021-11-12

摘要/Abstract

摘要： 使用PHREEQC软件及OECD/NEA出版的镅热力学数据,利用相关矿物的沉淀饱和指数,计算了镅在北山地下水中的赋存形态,探讨了pH值、方解石、CO₂分压及腐殖酸对镅的形态分布与溶解度的影响。结果表明,在近中性条件下镅主要以AmCO⁺₃和 AmSiO(OH)²⁺₃形式存在,在碱性条件下易形成AmOHCO₃·0.5H₂O(cr)和Am(OH)₃(cr)沉淀,因此偏碱性的北山地下水有利于阻滞镅的迁移。围岩中存在的方解石对镅的溶解度和迁移性影响较复杂,在pH 6～8条件下,方解石能微弱地降低镅的溶解度;在pH 8～9.7时,方解石会提高Am(CO₃)^-₂离子的浓度,进而提高镅的溶解度,增强其可迁移性;而在pH 9.7～11时,方解石有利于AmOHCO₃·0.5H₂O(cr)沉淀形成,从而降低镅的溶解度。当固定pH为7.56时,镅的溶解度随二氧化碳分压升高先降低而后增大,在10^-2.25 bar时达最低值。由于易与腐殖酸形成络合物,在弱酸性至弱碱性条件下腐殖酸能提升镅的溶解度,从而增强其可迁移性,应引起重视。

关键词: 高放废物地质处置, 镅, 形态分布, 溶解度, 腐殖酸

Abstract: Based on the thermodynamic datapublished by OECD/NEA and the estimated saturation indices for the precipitation of secondary minerals, the influence of pH, calcite, CO₂, and humic acid (HA) on the speciation distribution and solubility of Americium (Am) in Beishan groundwater were investigated using PHREEQC software. The results indicated that Am mainly occurred as AmCO⁺₃ and AmSiO(OH)²⁺₃ at nearly neutral condition, whereas AmOHCO₃·0.5H₂O(cr) and Am(OH)₃(cr) became predominantly at alkaline condition. Therefore, alkaline Beishan groundwater is favorable for the retardation of Am. Calcite exhibited a complex effect on the solubility and mobility of Am. At pH 6—8, it can decrease the solubility of Am slightly; at pH 8—9.7, the formation of anionic Am(CO₃)^-₂ was favorable thus the solubility and mobility of Am increased in presence of calcite; whereas as pH increased to 9.7—11, calcite can decrease the solubility of Am because of the formation of AmOHCO₃·0.5H₂O(cr). When pH was fixed at 7.56, the solubility of americium decreased firstly and then increased subsequently with increasing CO₂ pressure, and reached a minimum value at 10^-2.25bar. The results also indicated that humic acid had strong affinity towards americium, and from nearly acidic to alkaline conditions it could increase the solubility and hence the mobility of americium.

Key words: geological disposal of high-level radioactive waste, americium, speciation distribution, solubility, humic acid

中图分类号:

TL942+.1

郭辉, 康明亮, 陈万良, 龙俊辰, 赵准. 镅在北山地下水中赋存形态及溶解度分析[J]. 辐射防护, 2016, 36(1): 40-46.

Guo Hui, Kang Mingliang, Chen Wanliang, Long Junchen, Zhao Zhun. Speciation and solubility of americium in Beishan groundwater[J]. RADIATION PROTECTION, 2016, 36(1): 40-46.

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