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Ma F, Dai Z, Zhang X, Hu Y, Cai F, Wang W, Tian Y, Soltanian MR. Quantifying the impact of upscaled parameters on radionuclide transport in three-dimensional fracture-matrix systems. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 930:172663. [PMID: 38653404 DOI: 10.1016/j.scitotenv.2024.172663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Revised: 03/18/2024] [Accepted: 04/19/2024] [Indexed: 04/25/2024]
Abstract
Assessing the long-term safety of geological repositories for high-level radioactive waste is critically dependent on understanding radionuclide transport in multi-scale fractured rocks. This study explores the influence of upscaled parameters on radionuclide movement within a three-dimensional fracture-matrix system using a discrete fracture-matrix (DFM) model. The developed numerical simulation workflow includes creating a random discrete fracture network, meshing of the fractures and matrix, assigning upscaled parameters, and conducting finite element simulations. We simulated the spatiotemporal evolution of radionuclide concentrations in the fractures and matrix over a century, revealing significant spatial heterogeneity driven by a heterogeneous seepage field. Employing geostatistics-based upscaling methods, we predicted the effective ranges of crucial solute transport parameters at the field scale. The matrix diffusion coefficient, matrix distribution coefficient, and longitudinal dispersivity were upscaled by factors of 2.0-3.0, 2.5-4.0, and 10-104, respectively, based on laboratory-scale measurements. Incorporating these upscaled parameters into the DFM model, we analyzed their impact on radionuclide transport. Our findings demonstrate that an upscaled matrix diffusion coefficient and matrix distribution coefficient result in a delayed transport of radionuclides in fractures by enhancing mass transfer between the fractures and rock matrix, while an upscaled longitudinal dispersivity accelerates transport by advancing the positions of concentration peaks. Sensitivity analysis revealed that the matrix distribution coefficient is the most impactful, followed by dispersivity and matrix diffusion coefficient. These insights are important for minimizing parameter uncertainties and enhancing the accuracy of predictions concerning radionuclide transport in multi-scale fractured rocks.
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Affiliation(s)
- Funing Ma
- School of Environmental and Municipal Engineering, Qingdao University of Technology, Qingdao 266520, China
| | - Zhenxue Dai
- School of Environmental and Municipal Engineering, Qingdao University of Technology, Qingdao 266520, China; College of Construction Engineering, Jilin University, Changchun 130026, China.
| | - Xiaoying Zhang
- College of Construction Engineering, Jilin University, Changchun 130026, China.
| | - Yingtao Hu
- Department of Civil Engineering, Hangzhou City University, Hangzhou 310015, China
| | - Fangfei Cai
- College of Construction Engineering, Jilin University, Changchun 130026, China
| | - Weiliang Wang
- School of Environmental and Municipal Engineering, Qingdao University of Technology, Qingdao 266520, China
| | - Yong Tian
- School of Environmental and Municipal Engineering, Qingdao University of Technology, Qingdao 266520, China
| | - Mohamad Reza Soltanian
- Departments of Geosciences and Environmental Engineering, University of Cincinnati, Cincinnati, OH, USA
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Tang Q, Xu Z, Tan Q, Shi X, Wu W, Pan D. Insight into Impact of Phosphate on the Cotransport and Corelease of Eu(III) with Bentonite Colloids in Saturated Quartz Columns. JOURNAL OF HAZARDOUS MATERIALS 2024; 461:132572. [PMID: 37742375 DOI: 10.1016/j.jhazmat.2023.132572] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 09/12/2023] [Accepted: 09/16/2023] [Indexed: 09/26/2023]
Abstract
Understanding the fate and transport of radionuclides in porous media reduces the risk of contaminating soils and groundwater systems. While the cotransport of bentonite colloids (BC) with radionuclides in saturated media is well documented, the role of phosphate (P) in the colloid-driven transport of radionuclides in saturated porous media is still unaddressed; in particular, phosphate increases the mobilities of radionuclides in porous media, which should be subjected to an environmental risk assessment and model construction. In this work, the effects of phosphate on the transport and release of Eu(III) in different colloid systems (P-Eu(III), P-BC, P-BC-Eu(III)) was investigated with a fundamental colloid chemistry approach and a range of characterization techniques. The results showed that intrinsic europium colloids with size of 685 nm were formed by precipitation with phosphate, which affected the mobility of Eu(III) due to colloid stability and physical straining. Phosphate enhanced BC and BC-Eu(III) transport, and a high phosphate concentration promoted BC transport by eliminating physical straining and enhancing the electrostatic repulsions. The crystal structure of EuPO4 was not destroyed by the subsequent introduction of BC, which carried EuPO4 for further migration. However, when phosphate, bentonite and Eu(III) coexisted in a colloid suspension, the phosphate promoted Eu(III) transport by preferentially interacting with the BC to form ternary BC-P-Eu(III) pseudo-colloids rather than forming the intrinsic EuPO4 colloids. The synergetic role of P and BC on Eu(III) transport involved a relatively complex process and was not a simply additive effect. The findings in this work highlight the significance of phosphate in controlling the fate and transport of Ln(III)/Am(III) radionuclides in the presence of intrinsic colloids and pseudo-colloids in P-rich colloid-bearing environments.
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Affiliation(s)
- Qingfeng Tang
- School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, China
| | - Zhen Xu
- School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, China; MOE Frontiers Science Center for Rare Isotopes, Lanzhou University, Lanzhou 730000, China.
| | - Qi Tan
- School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, China
| | - Xingyi Shi
- School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, China
| | - Wangsuo Wu
- School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, China; MOE Frontiers Science Center for Rare Isotopes, Lanzhou University, Lanzhou 730000, China
| | - Duoqiang Pan
- School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, China; MOE Frontiers Science Center for Rare Isotopes, Lanzhou University, Lanzhou 730000, China.
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Cai F, Ma F, Zhang X, Reimus P, Qi L, Wang Y, Lu D, Thanh HV, Dai Z. Investigating the influence of bentonite colloids on strontium sorption in granite under various hydrogeochemical conditions. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 900:165819. [PMID: 37506897 DOI: 10.1016/j.scitotenv.2023.165819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2023] [Revised: 07/08/2023] [Accepted: 07/24/2023] [Indexed: 07/30/2023]
Abstract
The disposal of high-level radioactive waste in deep geological repositories is a critical environmental issue. The presence of bentonite colloids generated in the engineering barrier can significantly impact the transport of radionuclides, but their effect on radionuclide sorption in granite remains poorly understood. This study aimed to investigate the sorption characteristics of strontium (Sr) on granite as well as on the coexistence system of granite and colloids under various hydrogeochemical conditions, through batch experiments. Fourier transform infrared spectroscopy was employed to analyze the sorption forms of Sr on granite before and after sorption. Several hydrogeochemical factors were examined, including contact time, pH, ionic strength, coexisting ions, and bentonite and humic acid colloid concentration. Among these factors, the concentration of bentonite colloids exhibited a significant effect on Sr sorption. Within a specific range of colloid concentration, the sorption of Sr on the solid system increased linearly with the bentonite colloid concentration. pH and ionic strength were also found to play crucial roles in the sorption process. At low pH, Sr sorption primarily occurred through the outer sphere's surface complexation and Na+/H+ ion exchange. However, at high pH, inner sphere surface complexation dominated the process. As the ionic strength increased, electrostatic repulsion gradually increased, resulting in fewer binding sites for particle aggregation and Sr sorption on bentonite colloids. The results also indicate that with increasing pH, the predominant forms of Sr in the solution transitioned from SrHCO3+ and SrCl+ to SrCO3 and SrCl+. This was mainly due to the ion exchange of Ca2+/Mg2+ in plagioclase and biotite, forming SrCO3 precipitation. These findings provide valuable insights into the transport behavior of radionuclides in the subsurface environment of the repository and highlight the importance of considering bentonite colloids and other hydrogeochemical factors when assessing the environmental impact of high-level radioactive waste disposal.
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Affiliation(s)
- Fangfei Cai
- College of Construction Engineering, Jilin University, Changchun 130026, China
| | - Funing Ma
- College of Construction Engineering, Jilin University, Changchun 130026, China.
| | - Xiaoying Zhang
- College of Construction Engineering, Jilin University, Changchun 130026, China.
| | - Paul Reimus
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Linlin Qi
- College of Construction Engineering, Jilin University, Changchun 130026, China
| | - Yu Wang
- Institute of Nuclear and New Technology, Tsinghua University, Beijing 100084, China
| | - Di Lu
- Yantai Customs Technology Center, Yantai 264000, China
| | - Hung Vo Thanh
- Laboratory for Computational Mechanics, Institute for Computational Science and Artificial Intelligence, Van Lang University, Ho Chi Minh City, Viet Nam; MEU Research Unit, Middle East University, Amman, Jordan
| | - Zhenxue Dai
- College of Construction Engineering, Jilin University, Changchun 130026, China
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Vivas EL, Kim KW, Suh YJ, Cho K. Fiber support prevents colloid-facilitated contamination induced by dissolution-precipitation of a calcium phosphate adsorbent. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2023; 342:118345. [PMID: 37311347 DOI: 10.1016/j.jenvman.2023.118345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 05/25/2023] [Accepted: 06/06/2023] [Indexed: 06/15/2023]
Abstract
During the adsorptive removal of hazardous metal contaminants, dissolution-precipitation of sparingly soluble adsorbents may result in the formation of toxic colloidal suspensions, triggering secondary pollution. Therefore, we studied the prevention of colloid-facilitated contamination in a model adsorption system of dicalcium phosphate dihydrate (DCPD, CaHPO4·2H2O) and Cd2+ as an adsorbent and adsorbate. Upon adding pure DCPD powder into a 500 mg L-1 Cd2+ solution of pH ≌ 7.0, aggregates of spheroidal Cd-bearing primary particles, within 0.040-0.95 μm size range, were generated via dissolution-precipitation. The accumulated volume of these submicron particles (10.8%) was greater than that of the submicron particles from the exposure of DCPD to deionized water (4.48%). While the Cd-carrying submicron particles, which are responsible for colloidal recontamination, appeared to form via homogeneous nucleation, their formation was suppressed using polyacrylonitrile fibers (PANFs) as supporting substrates. Thus, heterogeneous nucleation on PANFs formed hexagonal columnar microparticles of a new phase, pentacadmium dihydrogen tetrakis (phosphate) tetrahydrate (Cd5H2(PO4)4·4H2O). Together with dissolution-precipitation on the native DCPD, nucleation and growth on the PANFs accelerated the depletion of the dissolved species, reducing the degree of supersaturation along the DCPD-water interface. Although the PANFs decreased the Cd adsorption capacity to 56.7% of that of DCPD, they prevented the formation of small aggregates of Cd-bearing particles. Other sparingly soluble adsorbents can be compounded with PANF to prevent the generation of toxic colloids.
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Affiliation(s)
- Eleazer L Vivas
- Department of Environmental Engineering, Pusan National University, 2 Busandaehak-ro 63beon-gil, Geumjeong-gu, Busan, 46241, Republic of Korea
| | - Keon-Woo Kim
- Department of Environmental Engineering, Pusan National University, 2 Busandaehak-ro 63beon-gil, Geumjeong-gu, Busan, 46241, Republic of Korea
| | - Yong Jae Suh
- Resources Utilization Division, Korea Institute of Geoscience and Mineral Resources, 124 Gwahak-ro, Yuseong-gu, Daejeon, 34132, Republic of Korea; Department of Resources Engineering, Korea University of Science and Technology, 217 Gajeong-ro, Yuseong-gu, Daejeon, 34113, Republic of Korea.
| | - Kuk Cho
- Department of Environmental Engineering, Pusan National University, 2 Busandaehak-ro 63beon-gil, Geumjeong-gu, Busan, 46241, Republic of Korea.
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5
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Jia S, Dai Z, Zhou Z, Ling H, Yang Z, Qi L, Wang Z, Zhang X, Thanh HV, Soltanian MR. Upscaling dispersivity for conservative solute transport in naturally fractured media. WATER RESEARCH 2023; 235:119844. [PMID: 36931187 DOI: 10.1016/j.watres.2023.119844] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 02/14/2023] [Accepted: 03/07/2023] [Indexed: 06/18/2023]
Abstract
Physical heterogeneities are prevalent features of fracture systems and significantly impact transport processes in aquifers across different spatiotemporal scales. Upscaling solute transport parameter is an effective way of quantifying parameter variability in heterogeneous aquifers including fractured media. This paper develops conceptual models for upscaling conservative transport parameters in fracture media. The focus is on upscaling dispersivity. Lagrangian-based transport model (LBTM) for dispersivity upscaling are derived for the solute transport in two-dimensional fractures surrounded by an impermeable matrix. The LBTM is validated against the random walk particle tracking (RWPT) model, which enables highly efficient and accurate predictions of conservative solute transport. The results show that the derived scale-dependent analytical expressions are in excellent agreement with RWPT model results. In addition, LBTM results are also compared to experimental results from the observed breakthrough curve of a conservative solute transport through a single natural fracture within a granite core. Comparing results from the LBTM and transport experiment shows that LBTM based estimated dispersivity is 10.55% higher than the measured value. Errors introduced by the experiments, the conceptual assumptions in deriving models, and the heterogeneities of fracture apertures not fully sampled by measuring instruments are main factor for such discrepancy. The sensitivity analysis indicates that the longitudinal and transverse dispersivities are positively related to the integral scale and the variance of the log-fracture aperture. The longitudinal dispersivity is strongly contolled by the variance of the log-fracture aperture. The LBTM may be useful for directly predicting solute transports, requiring only the acquisition of fractured geostatistical data. This work provides a better understanding of transport processes in fractured media which ultimately control water quality across scales.
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Affiliation(s)
- Sida Jia
- Key Laboratory of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun, China; College of Construction Engineering, Jilin University, Changchun, China
| | - Zhenxue Dai
- Key Laboratory of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun, China; College of Construction Engineering, Jilin University, Changchun, China.
| | - Zhichao Zhou
- CNNC Key Laboratory on Geological Disposal of High-level Radioactive Waste, Beijing Research Institute of Uranium Geology, Beijing, China
| | - Hui Ling
- CNNC Key Laboratory on Geological Disposal of High-level Radioactive Waste, Beijing Research Institute of Uranium Geology, Beijing, China
| | - Zhijie Yang
- Key Laboratory of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun, China; College of Construction Engineering, Jilin University, Changchun, China
| | - Linlin Qi
- Key Laboratory of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun, China; College of Construction Engineering, Jilin University, Changchun, China
| | - Zihao Wang
- Key Laboratory of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun, China; College of Construction Engineering, Jilin University, Changchun, China
| | - Xiaoying Zhang
- Key Laboratory of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun, China; College of Construction Engineering, Jilin University, Changchun, China.
| | - Hung Vo Thanh
- Laboratory for Computational Mechanics, Institute for Computational Science and Artificial Intelligence, Van Lang University, Ho Chi Minh City, Viet Nam; Faculty of Mechanical - Electrical and Computer Engineering, School of Technology, Van Lang University, Ho Chi Minh City, Viet Nam
| | - Mohamad Reza Soltanian
- Departments of Geosciences and Environmental Engineering, University of Cincinnati, Cincinnati, OH, USA
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6
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Wei X, Pan D, Tan Q, Shi X, Hou J, Tang Q, Xu Z, Wu W, Ma B. Surface charge property governing co-transport of illite colloids and Eu(III) in saturated porous media. CHINESE CHEM LETT 2023. [DOI: 10.1016/j.cclet.2023.108275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
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7
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Wei Y, Xu X, Zhao L, Cao X. Numerical modeling investigations of colloid facilitated chromium migration considering variable-density flow during the coastal groundwater table fluctuation. JOURNAL OF HAZARDOUS MATERIALS 2023; 443:130282. [PMID: 36334571 DOI: 10.1016/j.jhazmat.2022.130282] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 10/17/2022] [Accepted: 10/27/2022] [Indexed: 06/16/2023]
Abstract
Fluctuation of the groundwater table in the coastal zone influences the migration of colloids in vadose zone, which can further carry contaminants to transport. To capture the variable-density water flow and the migration processes, this study developed a colloid-facilitated migration model by adjusting the adsorption coefficient and considering the relationship between colloid and salinity based on the experimental observations. This model was further applied to explore the effects of freshwater and seawater fluctuations on the migration and transformation of colloids and Cr in coastal vadose zones. The greater the hydraulic conductivity of the saturated aquifer was, the more Cr were discharged into the ocean by submarine groundwater discharge. Furthermore, the increase in the freshwater fluctuation amplitude expanded the pollution ranges of colloidal Cr and dissolved Cr. The rise of the seawater fluctuation amplitude had a more obvious reduction effect on the total solid retained Cr in the contaminant source, compared with that of the freshwater fluctuation. As the seawater fluctuation amplitude increased from 0.1 m to 0.8 m, the ratio of total solid retained Cr reduction in the contaminant source to the initial value increased from 1.8 % to 7.8 %. The results obtained from this study deepens our understanding of how colloids and contaminants migrate across a coastal area from vadose zone induced by the groundwater table fluctuation.
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Affiliation(s)
- Yaqiang Wei
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China; School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, China
| | - Xiaoyun Xu
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Ling Zhao
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Xinde Cao
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China; Shanghai Engineering Research Center of Solid Waste Treatment and Resource Recovery, Shanghai Jiao Tong University, Shanghai 200240, China; National Field Observation and Research Station of Erhai Lake Ecosystem, Yunnan 671000, China.
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8
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Lawrence J, Alagarsamy VK, Mohanadhas B, Natarajan N, Vasudevan M, Govindarajan SK. Nitrate transport in a fracture-skin-matrix system under non-isothermal conditions. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:18091-18112. [PMID: 36205874 DOI: 10.1007/s11356-022-23428-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 09/29/2022] [Indexed: 06/16/2023]
Abstract
Subsurface leaching of agricultural runoff has been identified to pose a serious hazard to the soil-water ecosystem and human health, mostly due to the associated contamination with nitrate. Our understanding of the nature of contaminant spread in the vadose and aquifer zones has been improved from recent mechanistic models on the flow and transport of contaminants through fractured porous media. The present study aims to explore the impacts of skin formation in a fracture-matrix aquifer system onto the nitrogen species transport under non-isothermal settings using numerical modeling. A finite-difference scheme was employed to capture the nitrogen concentration profile and kinetics of transformation by solving the derived partial differential equations. The results show evidence of an additional mass transfer from fracture to skin so as to reduce the migration of nitrogen species (NO3-N and N2) at the fracture-matrix interface thereby reducing the peak concentration of N2 by nearly 1.5 times in fracture after denitrification. Although the thermal conductivity of the rock matrix has a direct impact on the temperature distribution in fracture-skin-matrix profiles, the presence of skin has a cooling effect for a high-temperature influent (45 °C), which also deteriorates the propagation of organic N2 and NO3-N, within the fracture. An increase in the temperature coefficient of skin has resulted in an apparent reduction in nitrogen species migration, indicating the thermo-chemical feasibility of an intermediate skin favoring the mass transfer processes. The findings of this study can be extended toward realistic estimation of groundwater contamination risks and for the design of biological filters for in situ remediation.
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Affiliation(s)
- Jino Lawrence
- Department of Automobile Engineering, Sathyabama University, Chennai, Tamil Nadu, 600119, India
| | - Vanav Kumar Alagarsamy
- Department of Basic & Applied Science, National Institute of Technology-Arunachal Pradesh, Yupia, Arunachal Pradesh, 791113, India
| | - Berlin Mohanadhas
- Department of Civil Engineering, National Institute of Technology-Arunachal Pradesh, Yupia, Arunachal Pradesh, 791113, India
| | - Narayanan Natarajan
- Department of Civil Engineering, Dr. Mahalingam College of Engineering and Technology, Pollachi, Tamil Nadu, 642003, India.
| | - Mangottiri Vasudevan
- Smart and Healthy Infrastructure Lab, Department of Agricultural and Civil Engineering, Bannari Amman Institute of Technology, Sathyamangalam, Tamil Nadu, 638401, India
| | - Suresh Kumar Govindarajan
- Petroleum Engineering Program, Department of Ocean Engineering, Indian Institute of Technology-Madras, Chennai, Tamil Nadu, 600036, India
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9
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Co transport of bentonite colloids and Eu(III) transport in saturated heterogeneous porous media. J Radioanal Nucl Chem 2023. [DOI: 10.1007/s10967-022-08718-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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10
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Virot M, Dumas T, Cot-Auriol M, Moisy P, Nikitenko SI. Synthesis and multi-scale properties of PuO 2 nanoparticles: recent advances and open questions. NANOSCALE ADVANCES 2022; 4:4938-4971. [PMID: 36504736 PMCID: PMC9680947 DOI: 10.1039/d2na00306f] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Accepted: 08/15/2022] [Indexed: 05/28/2023]
Abstract
Due to the increased attention given to actinide nanomaterials, the question of their structure-property relationship is on the spotlight of recent publications. Plutonium oxide (PuO2) particularly plays a central role in nuclear energetics and a comprehensive knowledge about its properties when nanosizing is of paramount interest to understand its behaviour in environmental migration schemes but also for the development of advanced nuclear energy systems underway. The element plutonium further stimulates the curiosity of scientists due to the unique physical and chemical properties it exhibits around the periodic table. PuO2 crystallizes in the fluorite structure of the face-centered cubic system for which the properties can be significantly affected when shrinking. Identifying the formation mechanism of PuO2 nanoparticles, their related atomic, electronic and crystalline structures, and their reactivity in addition to their nanoscale properties, appears to be a fascinating and challenging ongoing topic, whose recent advances are discussed in this review.
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Affiliation(s)
- Matthieu Virot
- ICSM, Univ Montpellier, CEA, CNRS, ENSCM Marcoule France
| | - Thomas Dumas
- CEA, DEN, DMRC, Univ Montpellier Marcoule France
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Zhang X, Wang Z, Reimus P, Ma F, Soltanian MR, Xing B, Zang J, Wang Y, Dai Z. Plutonium reactive transport in fractured granite: Multi-species experiments and simulations. WATER RESEARCH 2022; 224:119068. [PMID: 36103780 DOI: 10.1016/j.watres.2022.119068] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2022] [Revised: 08/19/2022] [Accepted: 09/05/2022] [Indexed: 05/15/2023]
Abstract
Plutonium (Pu) in the subsurface environment can transport in different oxidation states as an aqueous solute or as colloidal particles. The transport behavior of Pu is affected by the relative abundances of these species and can be difficult to predict when they simultaneously exist. This study investigates the concurrent transport of Pu intrinsic colloids, Pu(IV)(aq) and Pu(V-VI)(aq) through a combination of controlled experiments and semi-analytical dual-porosity transport modeling. Pu transport experiments were conducted in a fractured granite at high and low flow rates to elucidate sorption processes and their scaling behavior. In the experiments, Pu(IV)(aq) was the least mobile of the Pu species, Pu(V-VI)(aq) had intermediate mobility, and the colloidal Pu, which consisted mainly of precipitated and/or hydrolyzed Pu(IV), was the most mobile. The semi-analytical modeling revealed that the sorption of each Pu species was rate-limited, as the sorption could not be described by assuming local equilibrium in the experiments. The model was able to describe the sorption of the different Pu species that occurring either on fracture surfaces, in the pores of the rock matrix, or simultaneously in both locations. While equally good fits to the data could be achieved using any of these assumptions, a fracture-dominated process was considered to be the most plausible because it provided the most reasonable estimates of sorption rate constants. Importantly, a key result of this work is that the sorption rate constant of all Pu species tends to decrease with increasing time scales, which implies that Pu will tend to be more mobile at longer time scales than observations at shorter time scales suggest. This result has important implications for predicting the environmental impacts of Pu in the safety assessments of geologic repositories for radioactive waste disposal, and we explore potential mechanistic bases for upscaling the sorption rate constants to time and distance scales that cannot be practically evaluated in experiments.
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Affiliation(s)
- Xiaoying Zhang
- Institute of Intelligent Simulation and Early Warning for Subsurface Environment, Jilin University, Changchun 130026, China; College of Construction Engineering, Jilin University, Changchun 130026, China
| | - Zheng Wang
- College of Construction Engineering, Jilin University, Changchun 130026, China
| | - Paul Reimus
- Los Alamos National Laboratory, Los Alamos, NM 87545, United States
| | - Funing Ma
- College of Construction Engineering, Jilin University, Changchun 130026, China
| | - Mohamad Reza Soltanian
- Departments of Geology and Environmental Engineering, University of Cincinnati, Cincinnati, OH, United States
| | - Baoshan Xing
- Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA 01003, United States
| | - Jianzheng Zang
- Institute of Nuclear and New Technology, Tsinghua University, Beijing 100084, China
| | - Yu Wang
- Institute of Nuclear and New Technology, Tsinghua University, Beijing 100084, China.
| | - Zhenxue Dai
- Institute of Intelligent Simulation and Early Warning for Subsurface Environment, Jilin University, Changchun 130026, China; College of Construction Engineering, Jilin University, Changchun 130026, China; Key Laboratory of Groundwater Resources and Environment, Ministry of Education, Changchun 130026, China.
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12
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Zheng L, Wang L, James SC, Chrysikopoulos CV. Colloid transport through a variable-aperture fracture under unfavorable attachment conditions: Characterization with a continuous time random walk model. Colloids Surf A Physicochem Eng Asp 2022. [DOI: 10.1016/j.colsurfa.2022.128822] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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13
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Cook M, Kleinschmidt R, Brugger J, Wong VNL. Transport and migration of plutonium in different soil types and rainfall regimes. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2022; 248:106883. [PMID: 35468420 DOI: 10.1016/j.jenvrad.2022.106883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 03/25/2022] [Accepted: 03/28/2022] [Indexed: 06/14/2023]
Abstract
Leaching and transport of contaminants is a complex interacting system affected by a suite of environmental factors. This study demonstrates the potential significance of weather events and moisture movement when interpreting plutonium (Pu) migration and advective transport in the soil matrix. Using a column transport experiment, two soil types, a sandy soil and clay-rich soil, were spiked with 238Pu as a tracer to observe the effect of simulated tropical and arid rainfall events on Pu mobility. Partition coefficients (Kd) were determined over a period of weeks and under varying rainfall rates to establish the impact of changing weather events on Pu mobility. The variability of these temporal Kds covers six orders of magnitude over a relatively brief time period. This demonstrates the necessity for non-static Kds to accurately describe Pu transport in these systems. The Pu Kds determined by these column transport experiments fall within the bounds of anticipated values (approximately 80-300,000 mL g-1) from immobile (magnitude 106 mL g-1) to moderately mobile (magnitude 101 mL g-1). The overall transport rate, shown by a decrease in calculated Kd, increases in environments where rainfall is more episodic, such as in arid regions as opposed to the consistently abundant rainfall in tropical regions. In contrast to the 238Pu spike, 239+240Pu resulting from contamination from nuclear tests in the sandy soil (aged for >30 years) showed higher mobility; we hypothesise that the ageing of the contamination, in particular Pu-bearing particles, accounts for this significant increase in Pu mobility. Low intensity, high frequency events in tropical sandy soil systems containing Pu particle contamination have the potential to mobilise Pu (>105 decrease in calculated Kd) over shorter periods of weeks, and not years as previously assumed. This increased mobility, when applied to radioecological models using Kd as a site-specific parameter, shows that there is likely to be a continued impact (risk quotient >1) on non-human biota in tropical sandy soil ecosystems.
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Affiliation(s)
- Megan Cook
- School of Earth, Atmosphere & Environment, Monash University, Australia.
| | - Ross Kleinschmidt
- Epic Environmental, PO Box 13058, Brisbane Queensland, 4003, Australia
| | - Joël Brugger
- School of Earth, Atmosphere & Environment, Monash University, Australia
| | - Vanessa N L Wong
- School of Earth, Atmosphere & Environment, Monash University, Australia
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14
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Xu Z, Pan D, Tang Q, Wei X, Liu C, Li X, Chen X, Wu W. Co-transport and co-release of Eu(III) with bentonite colloids in saturated porous sand columns: Controlling factors and governing mechanisms. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2022; 298:118842. [PMID: 35031401 DOI: 10.1016/j.envpol.2022.118842] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 12/21/2021] [Accepted: 01/09/2022] [Indexed: 06/14/2023]
Abstract
Accurate prediction of the colloid-driven transport of radionuclides in porous media is critical for the long-term safety assessment of radioactive waste disposal repository. However, the co-transport and corelease process of radionuclides with colloids have not been well documented, the intrinsic mechanisms for colloids-driven retention/transport of radionuclides are still pending for further discussion. Thus the controlling factors and governing mechanisms of co-transport and co-release behavior of Eu(III) with bentonite colloids (BC) were discussed and quantified by combining laboratory-scale column experiments, colloid filtration theory and advection dispersion equation model. The results showed that the role of colloids in facilitating or retarding the Eu(III) transport in porous media varied with cations concentration, pH, and humic acid (HA). The transport of Eu(III) was facilitated by the dispersed colloids under the low ionic strength and high pH conditions, while was impeded by the aggregated colloids cluster. The enhancement of Eu(III) transport was not monotonically risen with the increase of colloids concentration, the most optimized colloids concentration in facilitating Eu(III) transport was approximately 150 mg L-1. HA showed significant promotion on both Eu(III) and colloid transport because of not only its strong Eu(III) complexion ability but also the increased dispersion of HA-coated colloid particles. The HA and BC displayed a synergistic effect on Eu(III) transport, the co-transport occurred by forming the ternary BC-HA-Eu(III) hybrid. The transport patterns could be simulated well with a two-site model that used the advection dispersion equation by reflecting the blocking effect. The retarded Eu(III) on the stationary phase was released and remobilized by the introduction of colloids, or by a transient reduction in cation concentration. The findings are essential for predicting the geological fate and the migration risk of radionuclides in the repository environment.
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Affiliation(s)
- Zhen Xu
- Frontiers Science Center for Rare Isotopes, Lanzhou University, Lanzhou, 730000, China; School of Nuclear Science and Technology, Lanzhou University, Lanzhou, 730000, China
| | - Duoqiang Pan
- Frontiers Science Center for Rare Isotopes, Lanzhou University, Lanzhou, 730000, China; School of Nuclear Science and Technology, Lanzhou University, Lanzhou, 730000, China.
| | - Qingfeng Tang
- School of Nuclear Science and Technology, Lanzhou University, Lanzhou, 730000, China
| | - Xiaoyan Wei
- School of Nuclear Science and Technology, Lanzhou University, Lanzhou, 730000, China
| | - Chunli Liu
- Beijing National Laboratory for Molecular Sciences, Fundamental Science Laboratory on Radiochemistry and Radiation Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, China
| | - Xiaolong Li
- China Academy of Engineering Physics, Mianyang, 621000, China
| | - Ximeng Chen
- Frontiers Science Center for Rare Isotopes, Lanzhou University, Lanzhou, 730000, China; School of Nuclear Science and Technology, Lanzhou University, Lanzhou, 730000, China
| | - Wangsuo Wu
- Frontiers Science Center for Rare Isotopes, Lanzhou University, Lanzhou, 730000, China; School of Nuclear Science and Technology, Lanzhou University, Lanzhou, 730000, China
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15
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Zhang X, Ma F, Dai Z, Wang J, Chen L, Ling H, Soltanian MR. Radionuclide transport in multi-scale fractured rocks: A review. JOURNAL OF HAZARDOUS MATERIALS 2022; 424:127550. [PMID: 34740158 DOI: 10.1016/j.jhazmat.2021.127550] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 10/07/2021] [Accepted: 10/16/2021] [Indexed: 06/13/2023]
Abstract
Significant progress has been achieved on radionuclide transport in fractured rocks due to worldwide urgent needs for geological disposal of high-level radioactive waste (HLW). Transport models designed with accurately constrained parameters are a fundamental prerequisite to assess the long-term safety of repositories constructed in deep formations. Focusing on geological disposal systems of HLW, this study comprehensively reviews the behavoir of radionuclides and transport processes in multi-scale fractured rocks. Three issues in transport modeling are emphasized: 1) determining parameters of radionuclide transport models in various scales from laboratory- to field-scale experiments, 2) upscaling physical and chemical parameters across scales, and 3) characterizing fracture structures for radionuclide transport simulations. A broad spectrum of contents is covered relevant to radionuclide transport, including laboratory and field scale experiments, analytical and numerical solutions, parameter upscaling, and conceptual model developments. This paper also discusses the latest progress of radionuclide migration in multi-scale fractured rocks and the most promising development trends in the future. It provides valuable insights into understanding radionuclide transport and long-term safety assessment for HLW geological repository.
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Affiliation(s)
- Xiaoying Zhang
- College of Construction Engineering, Jilin University, Changchun 130026, China
| | - Funing Ma
- College of Construction Engineering, Jilin University, Changchun 130026, China
| | - Zhenxue Dai
- College of Construction Engineering, Jilin University, Changchun 130026, China; Engineering Research Center of Geothermal Resources Development Technology and Equipment, Ministry of Education, Jilin University, Changchun, China.
| | - Ju Wang
- CNNC Key Laboratory on Geological Disposal of High-Level Radioactive Waste, Beijing Research Institute of Uranium Geology, Beijing 100029, China; CAEA Innovation Center on Geological Disposal of High Level Radioactive Waste, China
| | - Liang Chen
- CNNC Key Laboratory on Geological Disposal of High-Level Radioactive Waste, Beijing Research Institute of Uranium Geology, Beijing 100029, China; CAEA Innovation Center on Geological Disposal of High Level Radioactive Waste, China
| | - Hui Ling
- CNNC Key Laboratory on Geological Disposal of High-Level Radioactive Waste, Beijing Research Institute of Uranium Geology, Beijing 100029, China; CAEA Innovation Center on Geological Disposal of High Level Radioactive Waste, China
| | - Mohamad Reza Soltanian
- Department of Geology, University of Cincinnati, Cincinnati, OH, USA; Departments of Environmental Engineering, University of Cincinnati, Cincinnati, OH, USA
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Tran E, Zavrin M, Kersting AB, Klein-BenDavid O, Teutsch N, Weisbrod N. Colloid-facilitated transport of 238Pu, 233U and 137Cs through fractured chalk: Laboratory experiments, modelling, and implications for nuclear waste disposal. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 757:143818. [PMID: 33246722 DOI: 10.1016/j.scitotenv.2020.143818] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 10/26/2020] [Accepted: 10/27/2020] [Indexed: 06/12/2023]
Abstract
The influence of montmorillonite colloids on the mobility of 238Pu, 233U and 137Cs through a chalk fracture was investigated to assess the transport potential for radioactive waste. Radioisotopes of each element, along with the conservative tracer tritium, were injected in the presence and absence of montmorillonite colloids into a naturally fractured chalk core. In parallel, batch experiments were conducted to obtain experimental sorption coefficients (Kd, mL/g) for both montmorillonite colloids and the chalk fracture material. Breakthrough curves were modelled to determine diffusivity and sorption of each radionuclide to the chalk and the colloids under advective conditions. Uranium sorbed sparingly to chalk (log Kd = 0.7 ± 0.2) in batch sorption experiments. 233U(VI) breakthrough was controlled primarily by the matrix diffusion and sorption to chalk (15 and 25% recovery with and without colloids, respectively). Cesium, in contrast, sorbed strongly to both the montmorillonite colloids and chalk (batch log Kd = 3.2 ± 0.01 and 3.9 ± 0.01, respectively). The high affinity to chalk and low colloid concentrations overwhelmed any colloidal Cs transport, resulting in very low 137Cs breakthrough (1.1-5.5% mass recovery). Batch and fracture transport results, and the associated modelling revealed that Pu migrates both as Pu (IV) sorbed to montmorillonite colloids and as dissolved Pu(V) (7% recovery). Transport experiments revealed differences in Pu(IV) and Pu(V) transport behavior that could not be quantified in simple batch experiments but are critical to effectively predict transport behavior of redox-sensitive radionuclides. Finally, a brackish groundwater solution was injected after completion of the fracture flow experiments and resulted in remobilization and recovery of 2.2% of the total sorbed radionuclides which remained in the core from previous experiments. In general, our study demonstrates consistency in sorption behavior between batch and advective fracture transport. The results suggest that colloid-facilitated radionuclide transport will enhance radionuclide migration in fractured chalk for those radionuclides with exceedingly high affinity for colloids.
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Affiliation(s)
- Emily Tran
- Zuckerburg Institute for Water Research, Jacob Blaustein Institutes for Desert Research, Ben Gurion University of the Negev, Midreshet Ben Gurion 8499000, Israel
| | - Mavrik Zavrin
- Glenn T. Seaborg Institute, Lawrence Livermore National Laboratory, PO Box 808, Livermore, CA 94550, USA
| | - Annie B Kersting
- Glenn T. Seaborg Institute, Lawrence Livermore National Laboratory, PO Box 808, Livermore, CA 94550, USA
| | - Ofra Klein-BenDavid
- Nuclear Research Center of the Negev, Negev, P.O. Box 9001, Beersheva 8419001, Israel; Geological and Environmental Science Department, Ben Gurion University of the Negev, Beersheva 8410501, Israel
| | - Nadya Teutsch
- Geological Survey of Israel, 32 Yeshayahu Leibowitz St., Jerusalem 9371234, Israel
| | - Noam Weisbrod
- Zuckerburg Institute for Water Research, Jacob Blaustein Institutes for Desert Research, Ben Gurion University of the Negev, Midreshet Ben Gurion 8499000, Israel.
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17
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Yosri A, Dickson-Anderson S, Siam A, El-Dakhakhni W. Analytical description of colloid behavior in single fractures under irreversible deposition. J Colloid Interface Sci 2021; 589:597-604. [PMID: 33515975 DOI: 10.1016/j.jcis.2020.12.089] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 12/21/2020] [Accepted: 12/22/2020] [Indexed: 11/28/2022]
Abstract
OBJECTIVES Irreversible colloid deposition in groundwater-saturated fractures is typically modeled using a lumped deposition coefficient (κ) that reflects the system physiochemical conditions. A mathematical relationship between this coefficient and the physicochemical conditions controlling deposition has not yet been defined in the literature; thus, κ is typically fitted using experimental observations. This research develops, for the first time, an analytical relationship between κ and the fraction of colloids retained in single fractures (Fr). This relationship could be subsequently integrated with available models relating Fr to the system's physicochemical properties to develop an explicit mathematical relationship between κ and these properties. METHOD The Fr-κ analytical relationship was developed through conceptualizing irreversible deposition as first-order decay, as both lead to permanent mass loss, and coupling this with the advection-dispersion equation. The model estimates of colloid deposition were compared to observations from laboratory-scale colloid tracer experiments. A variance-based global sensitivity analysis was applied to identify the parameters controlling deposition. FINDINGS The analytical relationship efficiently replicated the experimental observations, and the global sensitivity analysis revealed that colloid deposition variability is controlled by fracture length, aperture size, and deposition coefficient; this supports the accepted understanding that colloid deposition is controlled by the system's physicochemical properties.
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Affiliation(s)
- Ahmed Yosri
- Department of Civil Engineering, McMaster University, Hamilton, Ontario L8S4L7, Canada.
| | | | - Ahmad Siam
- Department of Civil Engineering, McMaster University, Hamilton, Ontario L8S4L7, Canada.
| | - Wael El-Dakhakhni
- Department of Civil Engineering, McMaster University, Hamilton, Ontario L8S4L7, Canada.
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18
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Berlin M, Natarajan N, Vasudevan M, Kumar GS. Impact of Skin on the Movement of Nitrates in a Fractured Porous Media: Numerical Investigations. ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING 2021. [DOI: 10.1007/s13369-020-05174-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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19
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Plutonium migration in a rough single fractured granite. J Radioanal Nucl Chem 2019. [DOI: 10.1007/s10967-019-06981-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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20
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Joseph C, Balboni E, Baumer T, Treinen K, Kersting AB, Zavarin M. Plutonium Desorption from Nuclear Melt Glass-Derived Colloids and Implications for Migration at the Nevada National Security Site, USA. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:12238-12246. [PMID: 31589027 DOI: 10.1021/acs.est.9b03956] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The migration of low levels of plutonium has been observed at the Nevada National Security Site (NNSS) and attributed to colloids. To better understand the mechanism(s) of colloid-facilitated transport at this site, we performed flow cell desorption experiments with mineral colloid suspensions produced by hydrothermal alteration of NNSS nuclear melt glass, residual material left behind from nuclear testing. Three different colloid suspensions were used: (1) colloidal material from hydrothermal alteration of nuclear melt glass at 140 °C; (2) at 200 °C; and (3) plutonium sorbed to SWy-1 montmorillonite at room temperature. The 140 °C sample contained only montmorillonite, while zeolite and other phases were present in the 200 °C sample. Overall, more plutonium was desorbed from the 140 °C colloids (ca. 9-16%) than from the 200 °C colloids (ca. 4-8%). Furthermore, at the end of the 4.5 day flow cell experiments, the desorption rates for the 140 °C colloids and the Pu-montmorillonite colloids were similar while the desorption rates from the 200 °C colloids were up to an order of magnitude lower. We posit that the formation of zeolites and clays hydrothermally altered at 200 °C may lead to a more stable association of plutonium with colloids, resulting in lower desorption rates. This may give rise to more extensive colloid-facilitated transport and help explain why trace levels of plutonium are found downgradient from their original source decades after a nuclear detonation. Interestingly, in the case of cesium (a co-contaminant of plutonium), no difference was observed between the 140 and 200 °C colloids. This reflects intrinsic differences between cesium and plutonium sorption/desorption behavior (charge, cation size) and suggests that the Cs sorption mechanism (cation exchange) is not similarly affected by colloid formation temperature.
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Affiliation(s)
- Claudia Joseph
- Glenn T. Seaborg Institute, Physical & Life Sciences Directorate , Lawrence Livermore National Laboratory , L-231 , P.O. Box 808, Livermore , California 94550 , United States
| | - Enrica Balboni
- Glenn T. Seaborg Institute, Physical & Life Sciences Directorate , Lawrence Livermore National Laboratory , L-231 , P.O. Box 808, Livermore , California 94550 , United States
| | - Teresa Baumer
- Department of Civil & Environmental Engineering & Earth Sciences , University of Notre Dame , Notre Dame , Indiana 46556 , United States
| | - Kerri Treinen
- Glenn T. Seaborg Institute, Physical & Life Sciences Directorate , Lawrence Livermore National Laboratory , L-231 , P.O. Box 808, Livermore , California 94550 , United States
| | - Annie B Kersting
- Glenn T. Seaborg Institute, Physical & Life Sciences Directorate , Lawrence Livermore National Laboratory , L-231 , P.O. Box 808, Livermore , California 94550 , United States
| | - Mavrik Zavarin
- Glenn T. Seaborg Institute, Physical & Life Sciences Directorate , Lawrence Livermore National Laboratory , L-231 , P.O. Box 808, Livermore , California 94550 , United States
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21
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Tran EL, Teutsch N, Klein-BenDavid O, Kersting AB, Zavrin M, Weisbrod N. Radionuclide transport in brackish water through chalk fractures. WATER RESEARCH 2019; 163:114886. [PMID: 31357014 DOI: 10.1016/j.watres.2019.114886] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Revised: 07/16/2019] [Accepted: 07/18/2019] [Indexed: 06/10/2023]
Abstract
Mobility of radionuclides originating from geological repositories in the subsurface has been shown to be facilitated by clay colloids. In brackish water, however, colloids may flocculate and act to immobilize radionuclides associated with them. Furthermore, little research has been conducted on radionuclide interactions with carbonate rocks. Here, the impact of bentonite colloid presence on the transport of a cocktail of U(VI), Cs, Ce and Re through fractured chalk was investigated. Flow-through experiments were conducted with and without bentonite colloids, present as a mixture of bentonite and Ni-altered montmorillonite colloids. Ce was used as an analogue for reactive actinides in the (III) and (VI) redox states, and Re was considered an analogue for Tc. Filtered brackish groundwater (ionic strength = 170 mM) pumped from a fractured chalk aquitard in the northern Negev Desert of Israel, was used as a solution matrix. Rhenium transport was identical to that of the conservative tracer, uranine. The sorption coefficient (Kd) of U(VI), Cs and Re, calculated from batch experiments with crushed chalk, proved to be a good predictor of mass recovery in transport experiments conducted without bentonite colloids. A meaningful Kd value for Ce could not be calculated due to its precipitation as a Ce-carbonate colloids. Transport of both U(VI) and Cs was indifferent to the presence of bentonite colloids. However, the addition of bentonite in the injection solution effectively immobilized Ce, decreasing its recovery from 17-41% to 0.8-1.4%. This indicates that radionuclides which interact with clay colloids that undergo flocculation and deposition may effectively be immobilized in brackish aquifers. The results of this study have implications for the prediction of potential mobility of radionuclides in safety assessments for future geological repositories to be located in fractured carbonate rocks in general and in brackish groundwater in particular.
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Affiliation(s)
- Emily L Tran
- The Zuckerburg Institute for Water Research, The Jacob Blaustein Institutes for Desert Research, Ben Gurion University of the Negev, Midreshet Ben Gurion, 8499000, Israel
| | - Nadya Teutsch
- Geological Survey of Israel, 32 Yeshayahu Leibowitz St., Jerusalem, 9371234, Israel
| | - Ofra Klein-BenDavid
- Nuclear Research Center of the Negev, Negev, P.O. Box 9001, Beersheva, 8419001, Israel; Geological and Environmental Science Department, Ben Gurion University of the Negev, Beersheva, 8410501, Israel
| | - Annie B Kersting
- Lawrence Livermore National Laboratory, Livermore, CA, 94550, USA
| | - Mavrik Zavrin
- Lawrence Livermore National Laboratory, Livermore, CA, 94550, USA
| | - Noam Weisbrod
- The Zuckerburg Institute for Water Research, The Jacob Blaustein Institutes for Desert Research, Ben Gurion University of the Negev, Midreshet Ben Gurion, 8499000, Israel.
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22
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Yang J, Ge M, Jin Q, Chen Z, Guo Z. Co-transport of U(VI), humic acid and colloidal gibbsite in water-saturated porous media. CHEMOSPHERE 2019; 231:405-414. [PMID: 31146132 DOI: 10.1016/j.chemosphere.2019.05.091] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 05/01/2019] [Accepted: 05/12/2019] [Indexed: 06/09/2023]
Abstract
The release of uranyl from uranium tailing sites is a widely concerned environmental issue, with limited investigations on the effect of coexistence of various colloids. Gibbsite colloids extensively exist, together with ubiquitous humic substances, in uranium polluted waters at tailing sites, due to high concentration of dissolved Al in acid mine drainage. In this context, we investigated the co-transport of U(VI), gibbsite colloids and humic acid (HA) as a function of pH and ionic strength at a U(VI) concentration (5.0 × 10-5 M) relevant within mine tailings and related waste. It was found that, owing to electrostatic attraction, gibbsite colloids and HA associated with each other and transported simultaneously regardless of U(VI) presence. Besides the impact of pH and ionic strength, whether gibbsite colloids facilitated U(VI) transport depended on HA concentration. Gibbsite colloids impeded U(VI) transport at relatively low HA concentration (≤5 mg L-1), because associated colloids loaded with U(VI) were positively charged which favored colloid retention on negatively charged quartz sand in the column. U(VI) together with gibbsite colloids and low concentration HA was completely blocked at natural pH and/or high ionic strength. At relatively high HA concentration (20 mg L-1), however, the associated colloids showed negative zeta potential which facilitated U(VI) transport because of repulsion between negatively charged colloids and quartz sand. Meanwhile, high concentration of HA dramatically accelerated the transport of gibbsite colloids. These results implied that gibbsite colloids might imped U(VI) migration at uranium tailing sites unless the aquifers are enriched with abundant humic substances.
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Affiliation(s)
- Junwei Yang
- Radiochemistry Lab, School of Nuclear Science and Technology, Lanzhou University, Lanzhou, 730000, China; The Key Laboratory of Special Function Materials and Structure Design, Ministry of Education, Lanzhou University, 730000, Lanzhou, China
| | - Mengtuan Ge
- Radiochemistry Lab, School of Nuclear Science and Technology, Lanzhou University, Lanzhou, 730000, China; The Key Laboratory of Special Function Materials and Structure Design, Ministry of Education, Lanzhou University, 730000, Lanzhou, China
| | - Qiang Jin
- Radiochemistry Lab, School of Nuclear Science and Technology, Lanzhou University, Lanzhou, 730000, China; The Key Laboratory of Special Function Materials and Structure Design, Ministry of Education, Lanzhou University, 730000, Lanzhou, China
| | - Zongyuan Chen
- Radiochemistry Lab, School of Nuclear Science and Technology, Lanzhou University, Lanzhou, 730000, China; The Key Laboratory of Special Function Materials and Structure Design, Ministry of Education, Lanzhou University, 730000, Lanzhou, China.
| | - Zhijun Guo
- Radiochemistry Lab, School of Nuclear Science and Technology, Lanzhou University, Lanzhou, 730000, China; The Key Laboratory of Special Function Materials and Structure Design, Ministry of Education, Lanzhou University, 730000, Lanzhou, China.
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23
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Liu DX, Zuo R, Jivkov AP, Wang JS, Hu LT, Huang LX. Effect of colloids on non-Fickian transport of strontium in sediments elucidated by continuous-time random walk analysis. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2019; 252:1491-1499. [PMID: 31265960 DOI: 10.1016/j.envpol.2019.06.064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 05/14/2019] [Accepted: 06/17/2019] [Indexed: 06/09/2023]
Abstract
Understanding the influence of colloids on radionuclide migration is of significance to evaluate environmental risks for radioactive waste disposals. In order to formulate an appropriate modelling framework that can quantify and interpret the anomalous transport of Strontium (Sr) in the absence and presence of colloids, the continuous time random walk (CTRW) approach is implemented in this work using available experimental information. The results show that the transport of Sr and its recovery are enhanced in the presence of colloids. The causes can be largely attributed to the trap-release processes, e.g. electrostatic interactions of Sr, colloids and natural sediments, and differences in pore structures, which gave rise to the varying interstitial velocities of dissolved and, if any, colloid-associated Sr. Good agreement between the CTRW simulations and the column-scale observations is demonstrated. Regardless of the presence of colloids, the CTRW modelling captures the characteristics of non-Fickian anomalous transport (0 < β < 2) of Sr. In particular, a range of 0 < β < 1, corresponding to the cases with greater recoveries, reveal strongly non-Fickian transport with distinctive earlier arrivals and tailing effects, likely due to the physicochemical heterogeneities, i.e. the repulsive interactions and/or the macro-pores originating from local heterogeneities. The results imply that colloids can increase the Sr transport as a barrier of Sr sorption onto sediments herein, apart from often being carriers of sored radionuclides in aqueous phase. From a modelling perspective, the findings show that the established CTRW model is valid for quantifying the non-Fickian and promoted transport of Sr with colloids.
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Affiliation(s)
- Dong-Xu Liu
- College of Water Sciences, Beijing Normal University, Engineering Research Center of Groundwater Pollution Control and Remediation, Ministry of Education of China, Beijing 100875, PR China; Northwest Institute of Nuclear Technology, Xi'an 710024, PR China
| | - Rui Zuo
- College of Water Sciences, Beijing Normal University, Engineering Research Center of Groundwater Pollution Control and Remediation, Ministry of Education of China, Beijing 100875, PR China.
| | - Andrey P Jivkov
- Research Centre for Radwaste & Decommissioning and Modelling & Simulation Centre, Dalton Nuclear Institute, The University of Manchester, Manchester M13 9PL, UK
| | - Jin-Sheng Wang
- College of Water Sciences, Beijing Normal University, Engineering Research Center of Groundwater Pollution Control and Remediation, Ministry of Education of China, Beijing 100875, PR China
| | - Li-Tang Hu
- College of Water Sciences, Beijing Normal University, Engineering Research Center of Groundwater Pollution Control and Remediation, Ministry of Education of China, Beijing 100875, PR China
| | - Liu-Xing Huang
- Northwest Institute of Nuclear Technology, Xi'an 710024, PR China
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24
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Zavarin M, Zhao P, Joseph C, Begg JD, Boggs MA, Dai Z, Kersting AB. Hydrothermal Alteration of Nuclear Melt Glass, Colloid Formation, and Plutonium Mobilization at the Nevada National Security Site, U.S.A. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:7363-7370. [PMID: 31192587 DOI: 10.1021/acs.est.8b07199] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Approximately 2.8 t of plutonium (Pu) has been deposited in the Nevada National Security Site (NNSS) subsurface as a result of underground nuclear testing. Most of this Pu is sequestered in nuclear melt glass. However, Pu migration has been observed and attributed to colloid facilitated transport. To identify the mechanisms controlling Pu mobilization, long-term (∼3 year) laboratory nuclear melt glass alteration experiments were performed at 25 to 200 °C to mimic hydrothermal conditions in the vicinity of underground nuclear tests. The clay and zeolite colloids produced in these experiments are similar to those identified in NNSS groundwater. At 200 °C, maximum Pu and colloid concentrations of 30 Bq/L and 150 mg/L, respectively, were observed. However, much lower Pu and colloid concentrations were observed at 25 and 80 °C. These data suggest that Pu concentrations above the drinking water Maximum Contaminant Levels (0.56 Bq/L) may exist during early hydrothermal conditions in the vicinity of underground nuclear tests. However, formation of colloid-associated Pu will tend to decrease with time as nuclear test cavity temperatures decrease. Furthermore, median colloid concentrations in NNSS groundwater (1.8 mg/L) suggest that the high colloid and Pu concentrations observed in our 140 and 200 °C experiments are unlikely to persist in downgradient NNSS groundwater. While our experiments did not span all groundwater and nuclear melt glass conditions that may be present at the NNSS, our results are consistent with the documented low Pu concentrations in NNSS groundwater.
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Affiliation(s)
- Mavrik Zavarin
- Glenn T. Seaborg Institute, Physical & Life Sciences , Lawrence Livermore National Laboratory , Livermore , California 94550 , United States
| | - Pihong Zhao
- Glenn T. Seaborg Institute, Physical & Life Sciences , Lawrence Livermore National Laboratory , Livermore , California 94550 , United States
| | - Claudia Joseph
- Glenn T. Seaborg Institute, Physical & Life Sciences , Lawrence Livermore National Laboratory , Livermore , California 94550 , United States
| | - James D Begg
- Glenn T. Seaborg Institute, Physical & Life Sciences , Lawrence Livermore National Laboratory , Livermore , California 94550 , United States
| | - Mark A Boggs
- Glenn T. Seaborg Institute, Physical & Life Sciences , Lawrence Livermore National Laboratory , Livermore , California 94550 , United States
| | - Zurong Dai
- Glenn T. Seaborg Institute, Physical & Life Sciences , Lawrence Livermore National Laboratory , Livermore , California 94550 , United States
| | - Annie B Kersting
- Glenn T. Seaborg Institute, Physical & Life Sciences , Lawrence Livermore National Laboratory , Livermore , California 94550 , United States
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