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Zhu S, Wang Y, Zheng C, Wang Y, Tian Q, Henderson MJ, Yan M. Gaomiaozi bentonite colloids: Interactions with plutonium (IV) and zirconium (IV). Colloids Surf A Physicochem Eng Asp 2022. [DOI: 10.1016/j.colsurfa.2022.129636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Sun Y, Gao C, Jin Q, Chen Z, Guo Z. Effects of iron oxide coatings on the mobility and retardation of U(VI) in water saturated media. Colloids Surf A Physicochem Eng Asp 2021. [DOI: 10.1016/j.colsurfa.2021.127458] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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3
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Shi Y, Zhou W, Wang J, Xian D, Tan Z, Du L, Li X, Pan D, Chen Z, Wu W, Liu C. Effect of pH on the formation of U(VI) colloidal particles in a natural groundwater. J Radioanal Nucl Chem 2021. [DOI: 10.1007/s10967-020-07591-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Distribution and Geochemical Controls of Arsenic and Uranium in Groundwater-Derived Drinking Water in Bihar, India. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17072500. [PMID: 32268538 PMCID: PMC7177302 DOI: 10.3390/ijerph17072500] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Revised: 04/01/2020] [Accepted: 04/02/2020] [Indexed: 11/17/2022]
Abstract
Chronic exposure to groundwater containing elevated concentrations of geogenic contaminants such as arsenic (As) and uranium (U) can lead to detrimental health impacts. In this study, we have undertaken a groundwater survey of representative sites across all districts of the State of Bihar, in the Middle Gangetic Plain of north-eastern India. The aim is to characterize the inorganic major and trace element aqueous geochemistry in groundwater sources widely used for drinking in Bihar, with a particular focus on the spatial distribution and associated geochemical controls on groundwater As and U. Concentrations of As and U are highly heterogeneous across Bihar, exceeding (provisional) guideline values in ~16% and 7% of samples (n = 273), respectively. The strongly inverse correlation between As and U is consistent with the contrasting redox controls on As and U mobility. High As is associated with Fe, Mn, lower Eh and is depth-dependent; in contrast, high U is associated with HCO3−, NO3− and higher Eh. The improved understanding of the distribution and geochemical controls on As and U in Bihar has important implications on remediation priorities and selection, and may contribute to informing further monitoring and/or representative characterization efforts in Bihar and elsewhere in India.
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Yang J, Zhang Z, Chen Z, Ge M, Wu W, Guo Z. Co-transport of U(VI) and gibbsite colloid in saturated granite particle column: Role of pH, U(VI) concentration and humic acid. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 688:450-461. [PMID: 31252245 DOI: 10.1016/j.scitotenv.2019.05.395] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2019] [Revised: 05/17/2019] [Accepted: 05/25/2019] [Indexed: 06/09/2023]
Abstract
Understanding the in-situ transport behavior of U(VI) in granitic formations is of considerable interest for geological disposal of high-level radioactive wastes (HLW). In this context, the co-transport of U(VI) and representative naturally-occurring colloids, i.e., humic acid (HA) and gibbsite colloid (GC), was studied in granite column as a function of pH, U(VI) concentration and HA amount. It was found that, in addition to pH, co-transport of U(VI) and GC was also controlled by U(VI) concentration, the effect of which can be transport-facilitating and transport-impeding for U(VI) at relatively low concentration (2.0 × 10-6 mol/L) and for U(VI) at high concentration (5.0 × 10-5 mol/L), respectively. HA can present opposite effects on GC transport depending on HA amount. The transport-impeding effect by small amount of HA (5 mg/L) is due to strong aggregation between GC and HA from electrostatic attraction and complexation, whereas the transport-facilitating effect by big amount of HA (20 mg/L) is because of the complete HA coating which stabilizes associated colloids and alters surface charge from positive to negative. In ternary co-transport systems, a similar HA-dependent effect was also observed for both U(VI) and GC regardless of presence of high concentration U(VI). Besides the application of the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, the mechanisms behind binary and ternary co-transport of U(VI), GC and HA were also analyzed by assessing the evolutions of zeta potential and particle size in the column effluents. Finally, a two-site non-equilibrium model and a two-site kinetic attachment/detachment model were applied to describe the breakthrough curves of U(VI) and individual/combined colloids, respectively. The findings of this study indicated that combined effects of GC and HA on radionuclides transport is dominated by the amount of HA, and a facilitating transport of radionuclide can be expected in the underground environment rich in humic acid.
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Affiliation(s)
- Junwei Yang
- Radiochemistry Lab, School of Nuclear Science and Technology, Lanzhou University, 730000 Lanzhou, China; The Key Laboratory of Special Function Materials and Structure Design, Ministry of Education, Lanzhou University, 730000 Lanzhou, China
| | - Zhen Zhang
- Radiochemistry Lab, School of Nuclear Science and Technology, Lanzhou University, 730000 Lanzhou, 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, 730000 Lanzhou, 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, 730000 Lanzhou, China; The Key Laboratory of Special Function Materials and Structure Design, Ministry of Education, Lanzhou University, 730000 Lanzhou, China
| | - Wangsuo Wu
- Radiochemistry Lab, School of Nuclear Science and Technology, Lanzhou University, 730000 Lanzhou, 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, 730000 Lanzhou, China; The Key Laboratory of Special Function Materials and Structure Design, Ministry of Education, Lanzhou University, 730000 Lanzhou, China.
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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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Chen C, Zhao K, Shang J, Liu C, Wang J, Yan Z, Liu K, Wu W. Uranium (VI) transport in saturated heterogeneous media: Influence of kaolinite and humic acid. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2018; 240:219-226. [PMID: 29747106 DOI: 10.1016/j.envpol.2018.04.095] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Revised: 03/31/2018] [Accepted: 04/22/2018] [Indexed: 05/13/2023]
Abstract
Natural aquifers typically exhibit a variety of structural heterogeneities. However, the effect of mineral colloids and natural organic matter on the transport behavior of uranium (U) in saturated heterogeneous media are not totally understood. In this study, heterogeneous column experiments were conducted, and the constructed columns contained a fast-flow domain (FFD) and a slow-flow domain (SFD). The effect of kaolinite, humic acid (HA), and kaolinite/HA mixture on U(VI) retention and release in saturated heterogeneous media was examined. Media heterogeneity significantly influenced U fate and transport behavior in saturated subsurface environment. The presence of kaolinite, HA, and kaolinite/HA enhanced the mobility of U in heterogeneous media, and the mobility of U was the highest in the presence of kaolinite/HA and the lowest in the presence of kaolinite. In the presence of kaolinite, there was no difference in the amount of U released from the FFD and SFD. However, in the presence of HA and kaolinite/HA, a higher amount of U was released from the FFD. The findings in this study showed that medium structure and mineral colloids, as well as natural organic matter in the aqueous phase had significant effects on U transport and fate in subsurface environment.
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Affiliation(s)
- Chong Chen
- Key Laboratory of Plant-Soil Interactions, The Ministry of Education, Key Laboratory of Arable Land Conservation in North China, The Ministry of Agriculture, College of Resources and Environmental Sciences, China Agricultural University, Beijing, 100193, China
| | - Kang Zhao
- Key Laboratory of Plant-Soil Interactions, The Ministry of Education, Key Laboratory of Arable Land Conservation in North China, The Ministry of Agriculture, College of Resources and Environmental Sciences, China Agricultural University, Beijing, 100193, China
| | - Jianying Shang
- Key Laboratory of Plant-Soil Interactions, The Ministry of Education, Key Laboratory of Arable Land Conservation in North China, The Ministry of Agriculture, College of Resources and Environmental Sciences, China Agricultural University, Beijing, 100193, China.
| | - Chongxuan Liu
- School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Jin Wang
- School of Environmental Science and Engineering, Guangzhou University, Guangzhou, 510006, China
| | - Zhifeng Yan
- Institute of Surface-Earth System Science, Tianjin University, Tianjin, 300072, China
| | - Kesi Liu
- Department of Grassland Science, China Agricultural University, Beijing, 100193, China
| | - Wenliang Wu
- Beijing Key Laboratory of Farmland Soil Pollution Prevention and Remediation, College of Resources and Environmental Sciences, China Agricultural University, Beijing, 100193, China
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Almahayni T, Vanhoudt N. Does leaching of naturally occurring radionuclides from roadway pavements stabilised with coal fly ash have negative impacts on groundwater quality and human health? JOURNAL OF HAZARDOUS MATERIALS 2018; 349:128-134. [PMID: 29414744 DOI: 10.1016/j.jhazmat.2018.01.029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Revised: 01/11/2018] [Accepted: 01/13/2018] [Indexed: 06/08/2023]
Abstract
We assessed the potential impact of using coal fly ash to stabilise roadway pavements on groundwater quality and human health. The leaching potential of naturally occurring radionuclides (NORs) typically present in the fly ash was assessed with the HYDRUS-1D code and data representative of a segment of the Wisconsin State Trunk Highway 60 as a case study. Our assessment suggests that the impact would be mainly from the chemical toxicity of uranium (U). In our particular case study, U concentration in the leachate exceeded the maximum contaminant level for this element (MCL = 30 μg L-1) in almost all the scenarios. In the groundwater, the MCL was only exceeded under conditions of high leaching and low dilution in the aquifer. The radiological toxicity from the consumption of the contaminated groundwater by a hypothetical adult, however, was at maximum 43% of the individual dose criterion (IDC = 0.1 mSv y-1). The results also highlight the need to consider site-specific conditions such as climate and hydrogeology when assessing the environmental impacts of utilising fly ash in roadway construction applications since they could have profound effects on the assessment findings. There is also a pressing need for reliable and representative data to support realistic assessments.
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Affiliation(s)
- T Almahayni
- Biosphere Impact Studies Unit, Belgian Nuclear Research Centre (SCK•CEN), Boeretang 200, 2400, Mol, Belgium.
| | - N Vanhoudt
- Biosphere Impact Studies Unit, Belgian Nuclear Research Centre (SCK•CEN), Boeretang 200, 2400, Mol, Belgium
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Jiménez-Reyes M, Solache-Ríos M. Adsorption of U(IV) by several geomaterials: kinetic, adsorbent dosage and thermodynamic. J Radioanal Nucl Chem 2018. [DOI: 10.1007/s10967-018-5847-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Du L, Li S, Li X, Wang P, Huang Z, Tan Z, Liu C, Liao J, Liu N. Effect of humic acid on uranium(VI) retention and transport through quartz columns with varying pH and anion type. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2017; 177:142-150. [PMID: 28667877 DOI: 10.1016/j.jenvrad.2017.06.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 06/11/2017] [Accepted: 06/17/2017] [Indexed: 06/07/2023]
Abstract
Humic acid (HA)1 is ubiquitous in the environment and is an important factor in the migration behavior of U(VI) in the geological medium. The present work investigated the effect of HA on the migration behavior of U(VI) using quartz column experiments at different pH values and in the presence of various anions. The U(VI) adsorption characteristics and speciation were also studied to illuminate further the migration behavior of U(VI). Our results indicated that, at pH 6.0, HA slightly increased the migration velocity of U(VI) during the initial phase and reduced the quantity of eluted U(VI) because of the formation of HA-U(VI). The relative concentration (c/c0) of U(VI)was higher in the HA-U system at pH 8.0 than that at pH 5.0 because of the higher solubility of HA in basic solutions and the difference in charge of HA-U(VI). In the U-HA-anion system at pH 6.0, the breakthrough pore volumes (PVs2) of U(VI) in electrolytes containing Cl- and SO42- anions (PV = 8) are much higher than for solutions containing phosphate (PV = 3), while the HA migration behavior was not significantly affected by the type of anion. Thus, the fast migration of U(VI) under HA and phosphate was attributed to phosphate rather than HA. This result suggests that phosphate should be given more attention in predictions of U(VI) migration, especially in regions with high groundwater phosphate content.
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Affiliation(s)
- Liang Du
- Key Laboratory of Radiation Physics and Technology, Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064, PR China; Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, PR China
| | - Shicheng Li
- Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, PR China
| | - Xiaolong Li
- Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, PR China
| | - Ping Wang
- Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, PR China
| | - Zhaoya Huang
- Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, PR China
| | - Zhaoyi Tan
- Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, PR China
| | - Chunli Liu
- Beijing National Laboratory for Molecular Science (BNLMS), College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, PR China
| | - Jiali Liao
- Key Laboratory of Radiation Physics and Technology, Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064, PR China
| | - Ning Liu
- Key Laboratory of Radiation Physics and Technology, Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064, PR China.
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Guo H, Jia Y, Wanty RB, Jiang Y, Zhao W, Xiu W, Shen J, Li Y, Cao Y, Wu Y, Zhang D, Wei C, Zhang Y, Cao W, Foster A. Contrasting distributions of groundwater arsenic and uranium in the western Hetao basin, Inner Mongolia: Implication for origins and fate controls. THE SCIENCE OF THE TOTAL ENVIRONMENT 2016; 541:1172-1190. [PMID: 26473717 DOI: 10.1016/j.scitotenv.2015.10.018] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Revised: 09/16/2015] [Accepted: 10/05/2015] [Indexed: 06/05/2023]
Abstract
Although As concentrations have been investigated in shallow groundwater from the Hetao basin, China, less is known about U and As distributions in deep groundwater, which would help to better understand their origins and fate controls. Two hundred and ninety-nine groundwater samples, 122 sediment samples, and 14 rock samples were taken from the northwest portion of the Hetao basin, and analyzed for geochemical parameters. Results showed contrasting distributions of groundwater U and As, with high U and low As concentrations in the alluvial fans along the basin margins, and low U and high As concentrations downgradient in the flat plain. The probable sources of both As and U in groundwater were ultimately traced to the bedrocks in the local mountains (the Langshan Mountains). Chemical weathering of U-bearing rocks (schist, phyllite, and carbonate veins) released and mobilized U as UO2(CO3)2(2-) and UO2(CO3)3(4-) species in the alluvial fans under oxic conditions and suboxic conditions where reductions of Mn and NO3(-) were favorable (OSO), resulting in high groundwater U concentrations. Conversely, the recent weathering of As-bearing rocks (schist, phyllite, and sulfides) led to the formation of As-bearing Fe(III) (hydr)oxides in sediments, resulting in low groundwater As concentrations. Arsenic mobilization and U immobilization occurred in suboxic conditions where reduction of Fe(III) oxides was favorable and reducing conditions (SOR). Reduction of As-bearing Fe(III) (hydr)oxides, which were formed during palaeo-weathering and transported and deposited as Quaternary aquifer sediments, was believed to release As into groundwater. Reduction of U(VI) to U(IV) would lead to the formation of uraninite, and therefore remove U from groundwater. We conclude that the contrasting distributions of groundwater As and U present a challenge to ensuring safe drinking water in analogous areas, especially with high background values of U and As.
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Affiliation(s)
- Huaming Guo
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, PR China; School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, PR China.
| | - Yongfeng Jia
- School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, PR China
| | - Richard B Wanty
- U.S. Geological Survey, MS 964d Denver Federal Center, Denver, CO 80225, USA
| | - Yuxiao Jiang
- School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, PR China
| | - Weiguang Zhao
- School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, PR China
| | - Wei Xiu
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, PR China; School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, PR China
| | - Jiaxing Shen
- School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, PR China
| | - Yuan Li
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, PR China; School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, PR China
| | - Yongsheng Cao
- School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, PR China
| | - Yang Wu
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, PR China
| | - Di Zhang
- School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, PR China
| | - Chao Wei
- School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, PR China; The National Institute of Metrology, Beijing 100013, PR China
| | - Yilong Zhang
- Institute of Hydrogeology and Environmental Geology, China Academy of Geological Sciences, Shijiazhuang, Hebei, 050061 PR China
| | - Wengeng Cao
- Institute of Hydrogeology and Environmental Geology, China Academy of Geological Sciences, Shijiazhuang, Hebei, 050061 PR China
| | - Andrea Foster
- US Geological Survey, 345 Middlefield Road, Menlo Park, CA 94025, USA
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Katzourakis VE, Chrysikopoulos CV. Modeling dense-colloid and virus cotransport in three-dimensional porous media. JOURNAL OF CONTAMINANT HYDROLOGY 2015; 181:102-13. [PMID: 26071628 DOI: 10.1016/j.jconhyd.2015.05.010] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Revised: 05/16/2015] [Accepted: 05/22/2015] [Indexed: 05/20/2023]
Abstract
A three-dimensional numerical model was developed to investigate the simultaneous transport (cotransport) of dense colloids and viruses in homogeneous, water saturated, porous media with horizontal uniform flow. The dense colloids are assumed to exist in two different phases: suspended in the aqueous phase, and attached reversibly and/or irreversibly onto the solid matrix. The viruses are assumed to exist in four different phases: suspended in aqueous phase, attached onto the solid matrix, attached onto suspended colloids, and attached onto colloids already attached onto the solid matrix. The viruses in each of the four phases are assumed to undergo inactivation with different rates. Moreover, the suspended dense colloids as well as viruses attached onto suspended dense colloids are assumed to exhibit a "restricted" settling velocity as a consequence of the gravitational force; whereas, viruses due to their small sizes and densities are assumed to have negligible "restricted" settling velocity. The governing differential equations were solved numerically with the finite difference schemes, implicitly or explicitly implemented. Model simulations have shown that the presence of dense colloid particles can either enhance or hinder the horizontal transport of viruses, but also can increase the vertical migration of viruses.
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Affiliation(s)
- Vasileios E Katzourakis
- Environmental Engineering Laboratory, Civil Engineering Department, University of Patras, Patras 26500, Greece
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Cheng T, Saiers JE. Effects of dissolved organic matter on the co-transport of mineral colloids and sorptive contaminants. JOURNAL OF CONTAMINANT HYDROLOGY 2015; 177-178:148-157. [PMID: 25938867 DOI: 10.1016/j.jconhyd.2015.04.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 04/04/2015] [Accepted: 04/12/2015] [Indexed: 06/04/2023]
Abstract
Colloid-facilitated transport of contaminants in the vadose zone has important implications to groundwater quality, and has received considerable attention. Natural organic matter (NOM) is ubiquitous in subsurface environments, and its influence on mineral colloids and solute transport has been well documented. However, research on the influence of NOM on colloid-facilitated transport is limited. The objective of this paper is to elucidate the effects of NOM on colloid-facilitated transport of a radioactive contaminant (Cs-137) within partially-saturated sediments. Measurements made with re-packed columns reveal that Cs-137 mobility was low when mineral colloids were absent and was unaffected by the presence of NOM. The addition of mineral colloids to influent increased Cs-137 mobility, and effluent Cs-137 was dominated by the colloid-associated form. When NOM was added to systems that contained mineral colloids and Cs-137, the mobility of Cs-137 further increased. A mathematical model simulating colloid-facilitated transport showed that NOM increases Cs-137 transport by increasing colloid mobility and reducing the rate of Cs-137 adsorption to the porous medium.
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Affiliation(s)
- Tao Cheng
- Department of Earth Sciences, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador A1B 3X5, Canada.
| | - James E Saiers
- School of Forestry & Environmental Studies, Yale University, New Haven, CT 06511, USA
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Wang Q, Cheng T, Wu Y. Influence of mineral colloids and humic substances on uranium(VI) transport in water-saturated geologic porous media. JOURNAL OF CONTAMINANT HYDROLOGY 2014; 170:76-85. [PMID: 25444118 DOI: 10.1016/j.jconhyd.2014.10.007] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2014] [Revised: 09/19/2014] [Accepted: 10/06/2014] [Indexed: 05/13/2023]
Abstract
Mineral colloids and humic substances often co-exist in subsurface environment and substantially influence uranium (U) transport. However, the combined effects of mineral colloids and humic substances on U transport are not clear. This study is aimed at quantifying U transport and elucidating geochemical processes that control U transport when both mineral colloids and humic acid (HA) are present. U-spiked solutions/suspensions were injected into water-saturated sand columns, and U and colloid concentrations in column effluent were monitored. We found that HA promoted U transport via (i) formation of aqueous U-HA complexes, and (ii) competition against aqueous U for surface sites on transport media. Illite colloids had no influence on U transport at pH5 in the absence of HA due to low mobility of the colloids. At pH9, U desorbed from mobile illite and the presence of illite decreased U transport. At pH5, high U transport occurred when both illite colloids and HA were present, which was attributed to enhanced U adsorption to illite colloids via formation of ternary illite-HA-U surface complexes, and enhanced illite transport due to HA attachment to illite and transport media. This study demonstrates that the combined effects of mineral colloids and HA on contaminant transport is different from simple addition of the individual effect.
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Affiliation(s)
- Qing Wang
- Environmental Science Program, Faculty of Science, Memorial University, St. John's, Newfoundland and Labrador A1B 3X7, Canada
| | - Tao Cheng
- Department of Earth Sciences, Memorial University, St. John's, Newfoundland and Labrador A1B 3X5, Canada.
| | - Yang Wu
- Department of Earth Sciences, Memorial University, St. John's, Newfoundland and Labrador A1B 3X5, Canada
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16
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Wei X, Shao M, Du L, Horton R. Humic acid transport in saturated porous media: influence of flow velocity and influent concentration. J Environ Sci (China) 2014; 26:2554-2561. [PMID: 25499504 DOI: 10.1016/j.jes.2014.06.034] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2014] [Revised: 06/05/2014] [Accepted: 06/09/2014] [Indexed: 06/04/2023]
Abstract
Understanding the transport of humic acids (HAs) in porous media can provide important and practical evidence needed for accurate prediction of organic/inorganic contaminant transport in different environmental media and interfaces. A series of column transport experiments was conducted to evaluate the transport of HA in different porous media at different flow velocities and influent HA concentrations. Low flow velocity and influent concentration were found to favor the adsorption and deposition of HA onto sand grains packed into columns and to give higher equilibrium distribution coefficients and deposition rate coefficients, which resulted in an increased fraction of HA being retained in columns. Consequently, retardation factors were increased and the transport of HA through the columns was delayed. These results suggest that the transport of HA in porous media is primarily controlled by the attachment of HA to the solid matrix. Accordingly, this attachment should be considered in studies of HA behavior in porous media.
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Affiliation(s)
- Xiaorong Wei
- State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A&F University, Yangling, Shaanxi 712100, China.
| | - Mingan Shao
- State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A&F University, Yangling, Shaanxi 712100, China; Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
| | - Lina Du
- State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Robert Horton
- Department of Agronomy, Iowa State University, Ames, IA 50011, USA
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17
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Ikeda-Ohno A, Harrison JJ, Thiruvoth S, Wilsher K, Wong HKY, Johansen MP, Waite TD, Payne TE. Solution speciation of plutonium and Americium at an Australian legacy radioactive waste disposal site. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:10045-53. [PMID: 25126837 DOI: 10.1021/es500539t] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
During the 1960s, radioactive waste containing small amounts of plutonium (Pu) and americium (Am) was disposed in shallow trenches at the Little Forest Burial Ground (LFBG), located near the southern suburbs of Sydney, Australia. Because of periodic saturation and overflowing of the former disposal trenches, Pu and Am have been transferred from the buried wastes into the surrounding surface soils. The presence of readily detected amounts of Pu and Am in the trench waters provides a unique opportunity to study their aqueous speciation under environmentally relevant conditions. This study aims to comprehensively investigate the chemical speciation of Pu and Am in the trench water by combining fluoride coprecipitation, solvent extraction, particle size fractionation, and thermochemical modeling. The predominant oxidation states of dissolved Pu and Am species were found to be Pu(IV) and Am(III), and large proportions of both actinides (Pu, 97.7%; Am, 86.8%) were associated with mobile colloids in the submicron size range. On the basis of this information, possible management options are assessed.
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Affiliation(s)
- Atsushi Ikeda-Ohno
- School of Civil and Environmental Engineering, The University of New South Wales , Sydney, New South Wales 2052, Australia
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18
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Size fractionated complexation of Tc(IV) with soil humic acids at varying solution conditions. J Radioanal Nucl Chem 2014. [DOI: 10.1007/s10967-014-3325-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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19
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Harguindeguy S, Crançon P, Pointurier F, Potin-Gautier M, Lespes G. Isotopic investigation of the colloidal mobility of depleted uranium in a podzolic soil. CHEMOSPHERE 2014; 103:343-348. [PMID: 24387914 DOI: 10.1016/j.chemosphere.2013.12.033] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Revised: 11/30/2013] [Accepted: 12/11/2013] [Indexed: 06/03/2023]
Abstract
The mobility and colloidal migration of uranium were investigated in a soil where limited amounts of anthropogenic uranium (depleted in the 235U isotope) were deposited, adding to the naturally occurring uranium. The colloidal fraction was assumed to correspond to the operational fraction between 10 kDa and 1.2 μm after (ultra)filtration. Experimental leaching tests indicate that approximately 8-15% of uranium is desorbed from the soil. Significant enrichment of the leachate in the depleted uranium (DU) content indicates that uranium from recent anthropogenic DU deposit is weakly bound to soil aggregates and more mobile than geologically occurring natural uranium (NU). Moreover, 80% of uranium in leachates was located in the colloidal fractions. Nevertheless, the percentage of DU in the colloidal and dissolved fractions suggests that NU is mainly associated with the non-mobile coarser fractions of the soil. A field investigation revealed that the calculated percentages of DU in soil and groundwater samples result in the enhanced mobility of uranium downstream from the deposit area. Colloidal uranium represents between 10% and 32% of uranium in surface water and between 68% and 90% of uranium in groundwater where physicochemical parameters are similar to those of the leachates. Finally, as observed in batch leaching tests, the colloidal fractions of groundwater contain slightly less DU than the dissolved fraction, indicating that DU is primarily associated with macromolecules in dissolved fraction.
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Affiliation(s)
- S Harguindeguy
- Université de Pau et des Pays de l'Adour, Laboratoire de Chimie Analytique Bio-Inorganique et Environnement, IPREM-UMR 5254 Pau, France; CEA, DAM, DIF, F-91297 Arpajon, France
| | - P Crançon
- CEA, DAM, DIF, F-91297 Arpajon, France
| | | | - M Potin-Gautier
- Université de Pau et des Pays de l'Adour, Laboratoire de Chimie Analytique Bio-Inorganique et Environnement, IPREM-UMR 5254 Pau, France
| | - G Lespes
- Université de Pau et des Pays de l'Adour, Laboratoire de Chimie Analytique Bio-Inorganique et Environnement, IPREM-UMR 5254 Pau, France.
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20
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Gilbert D, Jakobsen HH, Winding A, Mayer P. Co-transport of polycyclic aromatic hydrocarbons by motile microorganisms leads to enhanced mass transfer under diffusive conditions. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:4368-4375. [PMID: 24625194 DOI: 10.1021/es404793u] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The environmental chemodynamics of hydrophobic organic chemicals (HOCs) are often rate-limited by diffusion in stagnant boundary layers. This study investigated whether motile microorganisms can act as microbial carriers that enhance mass transfer of HOCs through diffusive boundary layers. A new experimental system was developed that allows (1) generation of concentration gradients of HOCs under the microscope, (2) exposure and direct observation of microorganisms in such gradients, and (3) quantification of HOC mass transfer. Silicone O-rings were integrated into a Dunn chemotaxis chamber to serve as sink and source for polycyclic aromatic hydrocarbons (PAHs). This resulted in stable concentration gradients in water (>24 h). Adding the model organism Tetrahymena pyriformis to the experimental system enhanced PAH mass transfer up to hundred-fold (benzo[a]pyrene). Increasing mass transfer enhancement with hydrophobicity indicated PAH co-transport with the motile organisms. Fluorescence microscopy confirmed such transport. The effective diffusivity of T. pyriformis, determined by video imaging microscopy, was found to exceed molecular diffusivities of the PAHs up to four-fold. Cell-bound PAH fractions were determined to range from 28% (naphthalene) to 92% (pyrene). Motile microorganisms can therefore function as effective carriers for HOCs under diffusive conditions and might significantly enhance mobility and availability of HOCs.
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Affiliation(s)
- Dorothea Gilbert
- Department of Environmental Science, Aarhus University , P.O. Box 358, 4000 Roskilde, Denmark
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21
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Tinnacher RM, Nico PS, Davis JA, Honeyman BD. Effects of fulvic acid on uranium(VI) sorption kinetics. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 47:6214-6222. [PMID: 23550952 DOI: 10.1021/es304677c] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
This study focuses on the effects of fulvic acid (FA) on uranium(VI) sorption kinetics to a silica sand. Using a tritium-labeled FA in batch experiments made it possible to investigate sorption rates over a wide range of environmentally relevant FA concentrations (0.37-23 mg L(-1) TOC). Equilibrium speciation calculations were coupled with an evaluation of U(VI) and FA sorption rates based on characteristic times. This allowed us to suggest plausible sorption mechanisms as a function of solution conditions (e.g., pH, U(VI)/FA/surface site ratios). Our results indicate that U(VI) sorption onto silica sand can be either slower or faster in the presence of FA compared to a ligand-free system. This suggests a shift in the underlying mechanisms of FA effects on U(VI) sorption, from competitive sorption to influences of U(VI)-FA complexes, in the same system. Changes in metal sorption rates depend on the relative concentrations of metals, organic ligands, and mineral surface sites. Hence, these results elucidate the sometimes conflicting information in the literature about the influence of organic matter on metal sorption rates. Furthermore, they provide guidance for the selection of appropriate sorption equilibration times for experiments that are designed to determine metal distribution coefficients (Kd values) under equilibrium conditions.
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Affiliation(s)
- Ruth M Tinnacher
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, Colorado 80401, United States
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22
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Mostofa KMG, Liu CQ, Feng X, Yoshioka T, Vione D, Pan X, Wu F. Complexation of Dissolved Organic Matter with Trace Metal Ions in Natural Waters. PHOTOBIOGEOCHEMISTRY OF ORGANIC MATTER 2013. [DOI: 10.1007/978-3-642-32223-5_9] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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23
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Yang Y, Saiers JE, Xu N, Minasian SG, Tyliszczak T, Kozimor SA, Shuh DK, Barnett MO. Impact of natural organic matter on uranium transport through saturated geologic materials: from molecular to column scale. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2012; 46:5931-8. [PMID: 22533547 DOI: 10.1021/es300155j] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The risk stemming from human exposure to actinides via the groundwater track has motivated numerous studies on the transport of radionuclides within geologic environments; however, the effects of waterborne organic matter on radionuclide mobility are still poorly understood. In this study, we compared the abilities of three humic acids (HAs) (obtained through sequential extraction of a peat soil) to cotransport hexavalent uranium (U) within water-saturated sand columns. Relative breakthrough concentrations of U measured upon elution of 18 pore volumes increased from undetectable levels (<0.001) in an experiment without HAs to 0.17 to 0.55 in experiments with HAs. The strength of the HA effect on U mobility was positively correlated with the hydrophobicity of organic matter and NMR-detected content of alkyl carbon, which indicates the possible importance of hydrophobic organic matter in facilitating U transport. Carbon and uranium elemental maps collected with a scanning transmission X-ray microscope (STXM) revealed uneven microscale distribution of U. Such molecular- and column-scale data provide evidence for a critical role of hydrophobic organic matter in the association and cotransport of U by HAs. Therefore, evaluations of radionuclide transport within subsurface environments should consider the chemical characteristics of waterborne organic substances, especially hydrophobic organic matter.
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Affiliation(s)
- Yu Yang
- School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut 06511, USA.
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24
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Schmeide K, Sachs S, Bernhard G. Np(V) reduction by humic acid: contribution of reduced sulfur functionalities to the redox behavior of humic acid. THE SCIENCE OF THE TOTAL ENVIRONMENT 2012; 419:116-123. [PMID: 22285088 DOI: 10.1016/j.scitotenv.2011.12.052] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Revised: 12/21/2011] [Accepted: 12/22/2011] [Indexed: 05/31/2023]
Abstract
The role of sulfur-containing functional groups in humic acids for the Np(V) reduction in aqueous solution has been studied with the objective to specify individual processes contributing to the overall redox activity of humic substances. For this, humic acid model substances type M1-S containing different amounts of sulfur (1.9, 3.9, 6.9 wt.%) were applied. The sulfur functionalities in these humic acids are dominated by reduced-sulfur species, such as thiols, dialkylsulfides and/or disulfides. The Np(V) reduction behavior of these humic acids has been studied in comparison to that of the sulfur-free humic acid type M1 at pH 5.0, 7.0 and 9.0 under anaerobic conditions by means of batch experiments. For Np redox speciation in solution, solvent extraction and ultrafiltration were applied. In addition, redox potentials of the sample solutions were monitored. At pH 5.0, both rate and extent of Np(V) to Np(IV) reduction were found to increase with increasing sulfur content of the humic acids. At pH 7.0 and 9.0, sulfur functional groups had only a slight influence on the reduction behavior of humic acid toward Np(V). Thus, in addition to quinoid moieties and non-quinoid phenolic OH groups, generally acknowledged as main redox-active sites in humic substances, sulfur functional groups have been identified as further redox-active moieties of humic substances being active especially in the slightly acidic pH range as shown for Np(V). Due to the low sulfur content of up to 2 wt.% in natural humic substances, their contribution to the total reducing capacity is smaller than that of the other redox-active functional groups.
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Affiliation(s)
- K Schmeide
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiochemistry, PO Box 51 01 19, 01314 Dresden, Germany.
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25
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Claveranne-Lamolère C, Aupiais J, Lespes G, Frayret J, Pili E, Pointurier F, Potin-Gautier M. Investigation of uranium–colloid interactions in soil by dual field-flow fractionation/capillary electrophoresis hyphenated with inductively coupled plasma-mass spectrometry. Talanta 2011; 85:2504-10. [DOI: 10.1016/j.talanta.2011.07.100] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Revised: 07/26/2011] [Accepted: 07/29/2011] [Indexed: 12/01/2022]
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26
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Sachs S, Bernhard G. Influence of humic acids on the actinide migration in the environment: suitable humic acid model substances and their application in studies with uranium—a review. J Radioanal Nucl Chem 2011. [DOI: 10.1007/s10967-011-1084-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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27
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Graham MC, Oliver IW, MacKenzie AB, Ellam RM, Farmer JG. Mechanisms controlling lateral and vertical porewater migration of depleted uranium (DU) at two UK weapons testing sites. THE SCIENCE OF THE TOTAL ENVIRONMENT 2011; 409:1854-1866. [PMID: 21345483 DOI: 10.1016/j.scitotenv.2011.01.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Revised: 12/23/2010] [Accepted: 01/06/2011] [Indexed: 05/30/2023]
Abstract
Uranium associations with colloidal and truly dissolved soil porewater components from two Ministry of Defence Firing Ranges in the UK were investigated. Porewater samples from 2-cm depth intervals for three soil cores from each of the Dundrennan and Eskmeals ranges were fractionated using centrifugal ultrafiltration (UF) and gel electrophoresis (GE). Soil porewaters from a transect running downslope from the Dundrennan firing area towards a stream (Dunrod Burn) were examined similarly. Uranium concentrations and isotopic composition were determined using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) and Multi-Collector-Inductively Coupled Plasma-Mass Spectrometry (MC-ICP-MS), respectively. The soils at Dundrennan were Fe- and Al-rich clay-loam soils whilst at Eskmeals, they were Fe- and Al-poor sandy soils; both, however, had similar organic matter contents due to the presence of a near-surface peaty layer at Eskmeals. These compositional features influenced the porewater composition and indeed the associations of U (and DU). In general, at Dundrennan, U was split between large (100kDa-0.2μm) and small (3-30kDa) organic colloids whilst at Eskmeals, U was mainly in the small colloidal and truly dissolved fractions. Especially below 10cm depth, association with large Fe/Al/organic colloids was considered to be a precursor to the removal of U from the Dundrennan porewaters to the solid phase. In contrast, the association of U with small organic colloids was largely responsible for inhibiting attenuation in the Eskmeals soils. Lateral migration of U (and DU) through near-surface Dundrennan soils will involve both large and small colloids but, at depth, transport of the smaller amounts of U remaining in the porewaters may involve large colloids only. For one of the Dundrennan cores the importance of redox-related processes for the re-mobilisation of DU was also indicated as Mn(IV) reduction resulted in the release of both Mn(II) and U(VI) into the truly dissolved phase.
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Affiliation(s)
- Margaret C Graham
- School of GeoSciences, Crew Building, University of Edinburgh, The King's Buildings, West Mains Road, Edinburgh, EH9 3JN, United Kingdom.
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28
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Albarran N, Missana T, García-Gutiérrez M, Alonso U, Mingarro M. Strontium migration in a crystalline medium: effects of the presence of bentonite colloids. JOURNAL OF CONTAMINANT HYDROLOGY 2011; 122:76-85. [PMID: 21196062 DOI: 10.1016/j.jconhyd.2010.11.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Revised: 10/08/2010] [Accepted: 11/21/2010] [Indexed: 05/30/2023]
Abstract
The effects of bentonite colloids on strontium migration in fractured crystalline medium were investigated. We analyzed first the transport behaviour of bentonite colloids alone at different flow rates; then we compared the transport behaviour of strontium as solute and of strontium previously adsorbed onto stable bentonite colloids at a water velocity of approximately 7.1·10(-6)m/s-224m/yr. Experiments with bentonite colloids alone showed that - at the lowest water flow rate used in our experiments (7.1·10(-6)m/s) - approximately 70% of the initially injected colloids were retained in the fracture. Nevertheless, the mobile colloidal fraction, moved through the fracture without retardation, at any flow rate. Bentonite colloids deposited over the fracture surface were identified during post-mortem analyses. The breakthrough curve of strontium as a solute, presented a retardation factor, R(f)~6, in agreement with its sorption onto the granite fracture surface. The breakthrough curve of strontium in the presence of bentonite colloids was much more complex, suggesting additional contributions of colloids to strontium transport. A very small fraction of strontium adsorbed on mobile colloids moved un-retarded (R(f)=1) and this fraction was much lower than the expected, considering the quantity of strontium initially adsorbed onto colloids (90%). This behaviour suggests the hypothesis of strontium sorption reversibility from colloids. On the other hand, bentonite colloids retained within the granite fracture played a major role, contributing to a slower strontium transport in comparison with strontium as a solute. This was shown by a clear peak in the breakthrough curve corresponding to a retardation factor of approximately 20.
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Affiliation(s)
- Nairoby Albarran
- CIEMAT, Departamento de Medioambiente, Avenida Complutense, 22 - 28040, Madrid, Spain.
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29
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Wan J, Dong W, Tokunaga TK. Method to attenuate U(VI) mobility in acidic waste plumes using humic acids. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2011; 45:2331-2337. [PMID: 21319737 DOI: 10.1021/es103864t] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Acidic uranium (U) groundwater plumes have resulted from acid-extraction of plutonium during the Cold War and from U mining and milling operations. A sustainable method for in situ immobilization of U under acidic conditions is not yet available. Here, we propose to use humic acids (HAs) for in situ U immobilization in acidic waste plumes. Our laboratory batch experiments show that HA can adsorb onto aquifer sediments rapidly, strongly and practically irreversibly. Adding HA greatly enhanced U adsorption capacity to sediments at pH below 5.0. Our column experiments using historically contaminated sediments from the Savannah River Site under slow flow rates (120 and 12 m/year) show that desorption of U and HA were nondetectable over 100 pore-volumes of leaching with simulated acidic groundwaters. Upon HA-treatment, 99% of the contaminant [U] was immobilized at pH ≤ 4.5, compared to 5% and 58% immobilized in the control columns at pH 3.5 and 4.5, respectively. These results indicate that HA-treatment is a promising in situ remediation method for acidic U waste plumes. As a remediation reagent, HAs are resistant to biodegradation, cost-effective, nontoxic, and easily introducible to the subsurface.
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Affiliation(s)
- Jiamin Wan
- Earth Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, United States.
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30
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Steudtner R, Müller K, Schmeide K, Sachs S, Bernhard G. Binary and ternary uranium(vi) humate complexes studied by attenuated total reflection Fourier-transform infrared spectroscopy. Dalton Trans 2011; 40:11920-5. [DOI: 10.1039/c1dt11089f] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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31
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Crançon P, Pili E, Charlet L. Uranium facilitated transport by water-dispersible colloids in field and soil columns. THE SCIENCE OF THE TOTAL ENVIRONMENT 2010; 408:2118-2128. [PMID: 20178885 DOI: 10.1016/j.scitotenv.2010.01.061] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2009] [Revised: 01/26/2010] [Accepted: 01/27/2010] [Indexed: 05/28/2023]
Abstract
The transport of uranium through a sandy podzolic soil has been investigated in the field and in column experiments. Field monitoring, numerous years after surface contamination by depleted uranium deposits, revealed a 20 cm deep uranium migration in soil. Uranium retention in soil is controlled by the <50 microm mixed humic and clayey coatings in the first 40 cm i.e. in the E horizon. Column experiments of uranium transport under various conditions were run using isotopic spiking. After 100 pore volumes elution, 60% of the total input uranium is retained in the first 2 cm of the column. Retardation factor of uranium on E horizon material ranges from 1300 (column) to 3000 (batch). In parallel to this slow uranium migration, we experimentally observed a fast elution related to humic colloids of about 1-5% of the total-uranium input, transferred at the mean porewater velocity through the soil column. In order to understand the effect of rain events, ionic strength of the input solution was sharply changed. Humic colloids are retarded when ionic strength increases, while a major mobilization of humic colloids and colloid-borne uranium occurs as ionic strength decreases. Isotopic spiking shows that both (238)U initially present in the soil column and (233)U brought by input solution are desorbed. The mobilization process observed experimentally after a drop of ionic strength may account for a rapid uranium migration in the field after a rainfall event, and for the significant uranium concentrations found in deep soil horizons and in groundwater, 1 km downstream from the pollution source.
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Affiliation(s)
- P Crançon
- CEA, DAM, DIF, F-91297 Arpajon, France.
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32
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Walshe GE, Pang L, Flury M, Close ME, Flintoft M. Effects of pH, ionic strength, dissolved organic matter, and flow rate on the co-transport of MS2 bacteriophages with kaolinite in gravel aquifer media. WATER RESEARCH 2010; 44:1255-69. [PMID: 20003998 DOI: 10.1016/j.watres.2009.11.034] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2009] [Revised: 10/27/2009] [Accepted: 11/16/2009] [Indexed: 05/24/2023]
Abstract
Viruses are often associated with colloids in wastewater and could be transported with colloids into groundwater from land disposal of human and animal effluent and sludge, causing contamination of groundwater. To investigate the role of colloids in the transport of viruses in groundwater, experiments were conducted using a 2m long column packed with heterogeneous gravel aquifer media. Bacteriophage MS2 was used as the model virus and kaolinite as the model colloid. Experimental data were analyzed using Temporal Moment Analysis and Filtration Theory. In the absence of kaolinite colloid, MS2 phage traveled slightly faster than the conservative tracer bromide (Br), with little differences observed between unfiltered and filtered MS2 phage (0.22 microm as the operational cut-off for colloid-free virus). In the presence of kaolinite colloids, MS2 phage breakthrough occurred concurrently with that of the colloidal particles and the time taken to reach the peak virus concentration was reduced, suggesting a colloid-facilitated virus transport in terms of peak-concentration time and velocity. Meanwhile mass recovery and magnitude of concentrations of the phages were significantly reduced, indicating colloid-assisted virus attenuation in terms of concentrations and mass. Decreasing the pH or increasing the ionic strength increased the level of virus attachment to the aquifer media and colloids, and virus transport became more retarded, resulting in lower peak-concentration, lower mass recovery, longer peak-concentration time, and greater apparent collision efficiency. Increasing the concentration of dissolved organic matter (DOM) or flow rate resulted in faster virus transport velocity, higher peak-concentrations and mass recoveries, and lower apparent collision efficiencies. The dual-role of colloids in transport viruses has important implications for risk analysis and remediation of virus-contaminated sites.
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Affiliation(s)
- Gillian E Walshe
- Institute of Environmental Science & Research Ltd, PO Box 29181, Christchurch, New Zealand
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33
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Prognosticating the humic complexation for redox sensitive actinides through analogy, using the charge neutralisation model. RADIOCHIM ACTA 2009. [DOI: 10.1524/ract.93.1.43.58296] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
AbstractThe complexation of redox sensitive elements by humic acid (HA), described through the charge neutralisation model (CNM), has been reviewed in order to have a comprehensive scope. The data acquired in HUMICS program on thorium(IV), and data available in the literature, were reinterpreted according to the CNM, and adapted to uranium(IV), neptunium(IV) and plutonium(IV) through analogy in order to draw a boundary prediction. Otherwise, available data obtained in the framework of the CNM were used, or adapted if necessary, for other redox states when the analogy is justified,i.e.Am3+-Cm3+for Pu3+, NpO2+for PuO2+and UO22+for PuO22+.The obtained speciation diagrams indicate that, when (HA)=100 mg/L, redox sensitive actinides should be reduced to their +IV state whenEh≤650 mV/SHE for plutonium,Eh≤100 mV/SHE for neptunium andEh≤-20 mV/SHE for U. Plutonium could be present as mixtures of plutonium(III) and (IV) depending on the pH value in reducing ground waters -150 ≤Eh(mV/SHE) ≤ 150. The known reduction of neptunium(V) to neptunium(IV) in Gorleben ground waters seems also well represented, so is the stability of uranium(VI) in humic solution whenEh≥ 100 mV/SHE. Conversely, the known association of plutonium(VI) in marine systems is not satisfactorily represented, so does is the uranium behaviour under reducing conditions. Experiments under well-controlled conditions are still needed to ascertain the plutonium and uranium comportment in the presence of humic acid.
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Vazquez GJ, Dodge CJ, Francis AJ. Bioreduction of U(VI)−Phthalate to a Polymeric U(IV)−Phthalate Colloid. Inorg Chem 2009; 48:9485-90. [DOI: 10.1021/ic900694k] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Gustavo J. Vazquez
- Environmental Sciences Department, Brookhaven National Laboratory, P.O. Box 5000, Upton, New York 11973
| | - Cleveland J. Dodge
- Environmental Sciences Department, Brookhaven National Laboratory, P.O. Box 5000, Upton, New York 11973
| | - Arokiasamy J. Francis
- Environmental Sciences Department, Brookhaven National Laboratory, P.O. Box 5000, Upton, New York 11973
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Claveranne-Lamolère C, Lespes G, Dubascoux S, Aupiais J, Pointurier F, Potin-Gautier M. Colloidal transport of uranium in soil: Size fractionation and characterization by field-flow fractionation-multi-detection. J Chromatogr A 2009; 1216:9113-9. [PMID: 19766227 DOI: 10.1016/j.chroma.2009.08.025] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2009] [Revised: 07/17/2009] [Accepted: 08/10/2009] [Indexed: 11/20/2022]
Abstract
The aim of this study was to characterize colloids associated with uranium by using an on-line fractionation/multi-detection technique based on asymmetrical flow field-flow fractionation (As-Fl-FFF) hyphenated with UV detector, multi angle laser light scattering (MALLS) and inductively coupling plasma-mass spectrometry (ICP-MS). Moreover, thanks to the As-Fl-FFF, the different colloidal fractions were collected and characterized by a total organic carbon analyzer (TOC). Thus it is possible to determine the nature (organic or inorganic colloids), molar mass, size (gyration and hydrodynamic radii) and quantitative uranium distribution over the whole colloidal phase. In the case of the site studied, two populations are highlighted. The first population corresponds to humic-like substances with a molar mass of (1500+/-300)gmol(-1) and a hydrodynamic diameter of (2.0+/-0.2)nm. The second one has been identified as a mix of carbonated nanoparticles or clays with organic particles (aggregates and/or coating of the inorganic particles) with a size range hydrodynamic diameter between 30 and 450nm. Each population is implied in the colloidal transport of uranium: maximum 1% of the uranium content in soil leachate is transported by the colloids in the site studied, according to the depth in the soil. Indeed, humic substances are the main responsible of this transport in sub-surface conditions whereas nanoparticles drive the phenomenon in depth conditions.
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Affiliation(s)
- Céline Claveranne-Lamolère
- Université de Pau et des Pays de l'Adour-CNRS, LCABIE, UMR 5254, IPREM, 2 avenue P. Angot, 64000 Pau, France
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36
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Zhang H, Tang Q, Tao Z. Effects of phosphate and Cr3+ on the sorption and transport of uranium(VI) on a silica column. J Radioanal Nucl Chem 2009. [DOI: 10.1007/s10967-008-7371-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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37
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Schmeide K, Bernhard G. Redox stability of neptunium(V) and neptunium(IV) in the presence of humic substances of varying functionality. RADIOCHIM ACTA 2009. [DOI: 10.1524/ract.2009.1661] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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38
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Effects of phosphate and fulvic acid on the sorption and transport of uranium(VI) on silica column. J Radioanal Nucl Chem 2008. [DOI: 10.1007/s10967-007-7177-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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39
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Oliver IW, Graham MC, MacKenzie AB, Ellam RM, Farmer JG. Depleted uranium mobility across a weapons testing site: isotopic investigation of porewater, earthworms, and soils. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2008; 42:9158-9164. [PMID: 19174886 DOI: 10.1021/es8013634] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The mobility and bioavailability of depleted uranium (DU) in soils at a UK Ministry of Defence (UK MoD) weapons testing range were investigated. Soil and vegetation were collected near a test-firing position and at eight points along a transect line extending approximately 200 m down-slope, perpendicular to the firing line, toward a small stream. Earthworms and porewaters were subsequently separated from the soils and both total filtered porewater (<0.2 microm) and discrete size fractions (0.2 microm-100 kDa, 100-30 kDa, 30-3 kDa, and <3 kDa)obtainedvia centrifugal ultrafiltration were examined. Uranium concentrations were determined by inductively coupled plasma optical emission spectrometry (ICP-OES) for soils and ICP-mass spectrometry (MS) for earthworms and porewaters, while 235U:238U atom ratios were determined by multicollector (MC)-ICP-MS. Comparison of the porewater and earthworm isotopic values with those of the soil solids indicated that DU released into the environment during weapons test-firing operations was more labile and more bioavailable than naturally occurring U in the soils at the testing range. Importantly, DU was shown to be present in soil porewater even at a distance of approximately 185 m from the test-firing position and, along the extent of the transect was apparently associated with organic colloids.
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Affiliation(s)
- Ian W Oliver
- Scottish Universities Environmental Research Centre, Rankine Avenue, Scottish Enterprise Technology Park, East Kilbride, UK.
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40
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Fischer C, Karius V, Weidler PG, Lüttge A. Relationship between micrometer to submicrometer surface roughness and topography variations of natural iron oxides and trace element concentrations. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:3250-3266. [PMID: 18302429 DOI: 10.1021/la703221k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The surface area and roughness of natural iron oxide precipitations were quantified by 3D optical microscopy in order to get information about fluid-rock interface topography in high-permeability zones. Converged surface roughness data of microscale to submicroscale topography show the predominance of macroporous half-pores (>500 nm) and the occurrence of smaller half-pores (<500 nm) that dominate the BET surface area of iron oxides. A relationship was found between the occurrence of macroporous surface structures (micrometer range) and the uranium content of iron oxide encrustations. Iron-normalized uranium concentrations of an X-ray amorphous iron oxide encrustation correlate linearly with maximum topography heights of 1 to 2 mum on hand specimen subsamples. Our study shows the potential importance of micrometer- to submicrometer-size surface features, whose environmental impact is often ignored.
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Affiliation(s)
- Cornelius Fischer
- Department of Earth Science, Rice University, 6100 Main Street, Houston, Texas, USA.
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41
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Ranville JF, Hendry MJ, Reszat TN, Xie Q, Honeyman BD. Quantifying uranium complexation by groundwater dissolved organic carbon using asymmetrical flow field-flow fractionation. JOURNAL OF CONTAMINANT HYDROLOGY 2007; 91:233-46. [PMID: 17196707 DOI: 10.1016/j.jconhyd.2006.11.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2004] [Revised: 08/04/2006] [Accepted: 11/12/2006] [Indexed: 05/13/2023]
Abstract
The long-term mobility of actinides in groundwaters is important for siting nuclear waste facilities and managing waste-rock piles at uranium mines. Dissolved organic carbon (DOC) may influence the mobility of uranium, but few field-based studies have been undertaken to examine this in typical groundwaters. In addition, few techniques are available to isolate DOC and directly quantify the metals complexed to it. Determination of U-organic matter association constants from analysis of field-collected samples compliments laboratory measurements, and these constants are needed for accurate transport calculations. The partitioning of U to DOC in a clay-rich aquitard was investigated in 10 groundwater samples collected between 2 and 30 m depths at one test site. A positive correlation was observed between the DOC (4-132 mg/L) and U concentrations (20-603 microg/L). The association of U and DOC was examined directly using on-line coupling of Asymmetrical Flow Field-Flow Fractionation (AsFlFFF) with UV absorbance (UVA) and inductively coupled plasma-mass spectrometer (ICP-MS) detectors. This method has the advantages of utilizing very small sample volumes (20-50 microL) as well as giving molecular weight information on U-organic matter complexes. AsFlFFF-UVA results showed that 47-98% of the DOC (4-136 mg C/L) was recovered in the AsFlFFF analysis, of which 25-64% occurred in the resolvable peak. This peak corresponded to a weight-average molecular weight of about 900-1400 Daltons (Da). In all cases, AsFlFFF-ICP-MS suggested that<or=2% of the U, likely present as U(VI), was complexed with the DOC. This result was in good agreement with the U speciation modeling performed on the sample taken from the 2.3 m depth, which predicted approximately 3% DOC-complexed U. This good agreement suggests that the AsFlFFF-ICP-MS method may be very useful for determining U-organic matter association in small volume samples. Because the pH (7.0-8.1) and carbonate concentrations of these waters are typical of many groundwaters, these data suggested that facilitated transport of U by DOC may be limited in its importance in many groundwater systems.
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Affiliation(s)
- James F Ranville
- Department of Chemistry and Geochemistry, Colorado School of Mines, Golden, CO 80401, United States.
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42
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Mibus J, Sachs S, Pfingsten W, Nebelung C, Bernhard G. Migration of uranium(IV)/(VI) in the presence of humic acids in quartz sand: a laboratory column study. JOURNAL OF CONTAMINANT HYDROLOGY 2007; 89:199-217. [PMID: 17052798 DOI: 10.1016/j.jconhyd.2006.08.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2004] [Revised: 08/16/2006] [Accepted: 08/22/2006] [Indexed: 05/12/2023]
Abstract
The migration behavior of U(IV) and U(VI) in the presence of humic acid was studied in a quartz sand system. Laboratory column experiments were performed using humic acid, U(VI) in humic acid absence, U(IV) and U(VI) in humic acid presence, and for comparison a conservative tracer. In experiments using humic acid, both redox species of U migrate nearly as fast as the conservative tracer. Humic acid accelerates the U(VI) breakthrough compared to the humic acid-free system. There are strong indications for a similar effect on the U(IV) transport. At the same time, a part of U(IV) and U(VI) associated with the humic acid is immobilized in the quartz sand due to humic colloid filtration thus producing a delaying effect. Tailing at a low concentration level was observed upon tracer elution. The experimental breakthrough curves were described by reactive transport modeling using equations for equilibrium and kinetic reactions. The present study demonstrates that humic acids can play an important role in the migration of actinides. As natural organic matter is ubiquitous in aquifer systems, the humic colloid-borne transport of actinides is of high relevance in performance assessment.
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Affiliation(s)
- Jens Mibus
- Forschungszentrum Rossendorf e.V., Institute of Radiochemistry, PO Box 510 119, D-01314 Dresden, Germany.
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Bryan ND, Jones DLM, Keepax RE, Farrelly DH, Abrahamsen LG, Pitois A, Ivanov P, Warwick P, Evans N. The role of humic non-exchangeable binding in the promotion of metal ion transport in groundwaters in the environment. ACTA ACUST UNITED AC 2007; 9:329-47. [PMID: 17410308 DOI: 10.1039/b701891f] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Metal ions form strong complexes with humic substances. When the metal ion is first complexed by humic material, it is bound in an 'exchangeable' mode. The metal ion in this fraction is strongly bound, however, if the metal-humic complex encounters a stronger binding site on a surface, then the metal ion may dissociate from the humic substance and be immobilised. However, over time, exchangeably-bound metal may transfer to a 'non-exchangeable' mode. Transfer into this mode and dissociation from it are slow, regardless of the strength of the competing sink, and so immobilisation may be hindered. A series of coupled chemical transport calculations has been performed to investigate the likely effects of non-exchangeable binding upon the transport of metal ions in the environment. The calculations show that metal in the non-exchangeable mode will have a significantly higher mobility than that in the exchangeable mode. The critical factor is the ratio of the non-exchangeable first-order dissociation rate constant and the residence time in the groundwater column, metal ion mobility increasing with decreasing rate constant. A second series of calculations has investigated the effect of the sorption to surfaces of humic/metal complexes on the transport of the non-exchangeably bound metal. It was found that such sorption may reduce mobility, depending upon the humic fraction to which the metal ion is bound. For the more weakly sorbing humic fractions, under ambient conditions (humic concentration etc.) the non-exchangeable fraction may still transport significantly. However, for the more strongly sorbed fractions, the non-exchangeable fraction has little effect upon mobility. In addition to direct retardation, sorption also increases the residence time of the non-exchangeable fraction, giving more time for dissociation and immobilisation. The non-exchangeable dissociation reaction, and the sorption reaction have been classified in terms of two Damkohler numbers, which can be used to determine the importance of chemical kinetics during transport calculations. These numbers have been used to develop a set of rules that determine when full chemical kinetic calculations are required for a reliable prediction, and when equilibrium may be assumed, or when the reactions are sufficiently slow that they may be ignored completely.
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Affiliation(s)
- Nick D Bryan
- Centre for Radiochemistry Research, School of Chemistry, University of Manchester, Oxford Road, Manchester, UKM13 9PL.
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Zheng Z, Wan J, Song X, Tokunaga TK. Sodium meta-autunite colloids: Synthesis, characterization, and stability. Colloids Surf A Physicochem Eng Asp 2006. [DOI: 10.1016/j.colsurfa.2005.08.032] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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45
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Palágyi Š, Laciok A. Sorption, desorption and extraction of uranium from some sands under dynamic conditions. ACTA ACUST UNITED AC 2006. [DOI: 10.1007/s10582-006-1056-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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46
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Breynaert E, Maes A. Column Precipitation Chromatography: An Approach to Quantitative Analysis of Eigencolloids. Anal Chem 2005; 77:5048-54. [PMID: 16053321 DOI: 10.1021/ac050546+] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A new column precipitation chromatography (CPC) technique, capable of quantitatively measuring technetium eigencolloids in aqueous solutions, is presented. The CPC technique is based on the destabilization and precipitation of eigencolloids by polycations in a confined matrix. Tc(IV) colloids can be quantitatively determined from their precipitation onto the CPC column (separation step) and their subsequent elution upon oxidation to pertechnetate by peroxide (elution step). A clean-bed particle removal model was used to explain the experimental results.
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Affiliation(s)
- E Breynaert
- Department of Interphase Chemistry, K. U. Leuven, Kasteelpark Arenberg 23, B-3001 Leuven, Belgium
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47
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Interaction of actinides(III) with aluminosilicate colloids in “statu nascendi”. Colloids Surf A Physicochem Eng Asp 2005. [DOI: 10.1016/j.colsurfa.2004.11.023] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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48
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Pang L, Close ME, Noonan MJ, Flintoft MJ, van den Brink P. A laboratory study of bacteria-facilitated cadmium transport in alluvial gravel aquifer media. JOURNAL OF ENVIRONMENTAL QUALITY 2005; 34:237-247. [PMID: 15647554 DOI: 10.2134/jeq2005.0237] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Colloids, including bacteria, can dramatically accelerate the transport of heavy metals in ground water. Batch and column experiments were conducted to investigate adsorption of cadmium (Cd) onto Bacillus subtilis spores or Escherichia coli vegetative cells and Cd transport in alluvial gravel aquifer media in the presence of these bacteria. Results of the batch experiments showed that adsorption of Cd onto the bacteria was (i) positively related to solution pH, bacterial concentration, and negative surface charge, but inversely related to Cd concentration and (ii) a rate-limited nonlinear process, but adsorption onto E. coli was much less. For column influent Cd concentrations of about 4 mg/L and bacterial concentrations of > or = 10(5) colony-forming units (cfu)/mL, there was a significant increase in total Cd effluent concentrations. In comparison with controls that did not have bacteria-facilitated transport, Cd traveled 17 to 20 times faster when it traveled with mobile bacteria. However, Cd traveled mostly 2 to 3 times slower during the desorption phase under the influence of bacteria retained in the column. The difference between total and dissolved Cd concentrations was significant during Cd cotransport with B. subtilis spores, but this concentration difference was very small during Cd cotransport with E. coli, suggesting an adsorption-dominant mechanism during Cd cotransport with the spores and the possibility of Cd chelation by the dissolved membrane vesicles secreted from E. coli cell walls. Bacteria-facilitated transport of heavy metals may pose a threat to ground water quality in sites such as landfills and following land disposal of industrial and domestic effluent and sludge.
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Affiliation(s)
- L Pang
- Institute of Environmental Science & Research Ltd, PO Box 291 81, Christchurch, New Zealand.
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49
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Interaction of actinides with aluminosilicate colloids in statu nascendi. Colloids Surf A Physicochem Eng Asp 2003. [DOI: 10.1016/s0927-7757(03)00351-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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50
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Artinger R, Schuessler W, Schaefer T, Kim JI. A kinetic study of Am(III)/humic colloid interactions. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2002; 36:4358-4363. [PMID: 12387409 DOI: 10.1021/es025594f] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The interaction kinetics of the Am(III) ion with aquatic humic colloids is investigated under near-natural conditions by column experiments with a sandy aquifer sample rich in humic substancesforthe appraisal of the migration behavior of Am. The association and dissociation kinetics of the Am ion onto and from humic colloids control the migration of colloid-borne Am. As the contact time between Am and humic colloids prior to introduction into a column is increased, the mobility of colloid-borne Am is enhanced and hence the recovery of Am in the effluent increases. On the other hand, an increase of the migration time and residence time in column, respectively, reduces the Am recovery. Considering these experimental results a refined version of the kinetic model KICAM (Kinetically Controlled Availability Model), which suggests different Am binding modes with humic colloids, was developed. Applying KICAM it is possible to predict static and dynamic experiments affected by the kinetically controlled Am/humic colloid interactions over the range of 1 h up to several months. However, to apply these experimental results to long-term conditions, the Am binding scheme as proposed in KICAM needs to be verified. This paper provides, therefore, a basis for a better understanding of the colloid-borne Am migration in porous aquifer systems.
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Affiliation(s)
- Robert Artinger
- Forschungszentrum Karlsruhe, Institut für Nukleare Entsorgung, Germany.
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