1
|
Lu X, Zhang YY, Cheng W, Liu Y, Li Q, Li X, Dong F, Li J, Nie X. Chelating Effect of Siderophore Desferrioxamine-B on Uranyl Biomineralization Mediated by Shewanella putrefaciens. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:3974-3984. [PMID: 38306233 DOI: 10.1021/acs.est.3c05753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2024]
Abstract
In contaminated water and soil, little is known about the role and mechanism of the biometabolic molecule siderophore desferrioxamine-B (DFO) in the biogeochemical cycle of uranium due to complicated coordination and reaction networks. Here, a joint experimental and quantum chemical investigation is carried out to probe the biomineralization of uranyl (UO22+, referred to as U(VI) hereafter) induced by Shewanella putrefaciens (abbreviated as S. putrefaciens) in the presence of DFO and Fe3+ ion. The results show that the production of mineralized solids {hydrogen-uranium mica [H2(UO2)2(PO4)2·8H2O]} via S. putrefaciens binding with UO22+ is inhibited by DFO, which can both chelate preferentially UO22+ to form a U(VI)-DFO complex in solution and seize it from U(VI)-biominerals upon solvation. However, with Fe3+ ion introduced, the strong specificity of DFO binding with Fe3+ causes re-emergence of biomineralization of UO22+ {bassetite [Fe(UO2)2(PO4)2·8(H2O)]} by S. putrefaciens, owing to competitive complexation between Fe3+ and UO22+ for DFO. As DFO possesses three hydroxamic functional groups, it forms hexadentate coordination with Fe3+ and UO22+ ions via these functional groups. The stability of the Fe3+-DFO complex is much higher than that of U(VI)-DFO, resulting in some DFO-released UO22+ to be remobilized by S. putrefaciens. Our finding not only adds to the understanding of the fate of toxic U(VI)-containing substances in the environment and biogeochemical cycles in the future but also suggests the promising potential of utilizing functionalized DFO ligands for uranium processing.
Collapse
Affiliation(s)
- Xiaojing Lu
- National Collaborative Innovation Center for Nuclear Waste and Environmental Safety, Southwest University of Science and Technology, Mianyang621000, China
- School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, China
| | - Yang-Yang Zhang
- Department of Chemistry and Guangdong Provincial Key Laboratory of Catalytic Chemistry, Southern University of Science and Technology, Shenzhen 518055, China
| | - Wencai Cheng
- National Collaborative Innovation Center for Nuclear Waste and Environmental Safety, Southwest University of Science and Technology, Mianyang621000, China
| | - Yingzhangyang Liu
- National Collaborative Innovation Center for Nuclear Waste and Environmental Safety, Southwest University of Science and Technology, Mianyang621000, China
| | - Qingrong Li
- National Collaborative Innovation Center for Nuclear Waste and Environmental Safety, Southwest University of Science and Technology, Mianyang621000, China
| | - Xiaoan Li
- Mianyang Central Hospital, NHC Key Laboratory of Nuclear Technology Medical Transformation, Mianyang 621000, China
| | - Faqin Dong
- National Collaborative Innovation Center for Nuclear Waste and Environmental Safety, Southwest University of Science and Technology, Mianyang621000, China
- Key Laboratory of Solid Waste Treatment and Resource Recycle of Ministry of Education, Southwest University of Science and Technology, Mianyang 621010, China
| | - Jun Li
- Department of Chemistry and Guangdong Provincial Key Laboratory of Catalytic Chemistry, Southern University of Science and Technology, Shenzhen 518055, China
- Department of Chemistry and Engineering Research Center of Advanced Rare-Earth Materials of Ministry of Education, Tsinghua University, Beijing 100084, China
| | - Xiaoqin Nie
- National Collaborative Innovation Center for Nuclear Waste and Environmental Safety, Southwest University of Science and Technology, Mianyang621000, China
- Key Laboratory of Solid Waste Treatment and Resource Recycle of Ministry of Education, Southwest University of Science and Technology, Mianyang 621010, China
| |
Collapse
|
2
|
Zhang Y, Huang R, Iepure M, Merriman S, Min Y. Geocolloidal interactions and relaxation dynamics under nanoconfinement: Effects of salinity and particle concentration. J Colloid Interface Sci 2023; 656:200-213. [PMID: 37989053 DOI: 10.1016/j.jcis.2023.11.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 10/28/2023] [Accepted: 11/01/2023] [Indexed: 11/23/2023]
Abstract
HYPOTHESIS Energy-related contaminants are frequently associated with geocolloids that translocate in underground fissures with dimensions comparable with geocolloids. To assess the transport and impact of energy-related contaminants in geological systems, fundamental understandings of interfacial behaviors of nanoparticles under confinement is imperative. We hypothesize that the dynamic properties of geocolloids, as well as their dependence on aqueous medium conditions would deviate from bulk behaviors under nanoconfinement. EXPERIMENTS Force profiles and rheological properties of 50 nm silica nanoparticles in aqueous media confined between mica surfaces as a function of surface separation, particle concentrations, and salinity were measured utilizing the surface forces apparatus. FINDINGS Force profiles revealed the critical surface separation for nonlinear rheological behaviors coincides with the onset of exponential repulsion between mica surfaces. When salts were absent, the normal forces and viscosity values of colloidal suspensions resembled pure water. In contrast, with salts, the force profiles and corresponding critical length scales were found to be highly sensitive to the particle concentration and the degree of confinement. A Newtonian to shear-thinning transition was captured with increasing degrees of confinement. Our results show that the interplay among confinement, particle, and ionic concentrations can alter the interparticle forces and rheological responses of true nanosized-colloidal suspensions and thus their transport behaviors under nanoconfinement for the first time.
Collapse
Affiliation(s)
- Yuanzhong Zhang
- Department of Chemical and Environmental Engineering, University of California, Riverside 92521 CA, USA
| | - Rundong Huang
- Department of Chemical and Environmental Engineering, University of California, Riverside 92521 CA, USA
| | - Monica Iepure
- Department of Chemical and Environmental Engineering, University of California, Riverside 92521 CA, USA
| | - Stephen Merriman
- School of Polymer Science and Polymer Engineering, University of Akron, 44325 OH, USA
| | - Younjin Min
- Department of Chemical and Environmental Engineering, University of California, Riverside 92521 CA, USA; Material Science and Engineering Program, University of California, Riverside, 92521 CA, USA.
| |
Collapse
|
3
|
Chardi KJ, Schenkeveld WDC, Kumar N, Giammar DE, Kraemer SM. Effect of Competing Metals and Humic Substances on Uranium Mobilization from Noncrystalline U(IV) Induced by Anthropogenic and Biogenic Ligands. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:16006-16015. [PMID: 37819156 PMCID: PMC10603774 DOI: 10.1021/acs.est.3c01705] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 09/08/2023] [Accepted: 09/12/2023] [Indexed: 10/13/2023]
Abstract
Anthropogenic and biogenic ligands may mobilize uranium (U) from tetravalent U (U(IV)) phases in the subsurface, especially from labile noncrystalline U(IV). The rate and extent of U(IV) mobilization are affected by geochemical processes. Competing metals and humic substances may play a decisive role in U mobilization by anthropogenic and biogenic ligands. A structurally diverse set of anthropogenic and biogenic ligands was selected for assessing the effect of the aforementioned processes on U mobilization from noncrystalline U(IV), including 2,6-pyridinedicarboxylic acid (DPA), citrate, N,N'-di(2-hydroxybenzyl)ethylene-diamine-N,N'-diacetic acid (HBED), and desferrioxamine B (DFOB). All experiments were performed under anoxic conditions at pH 7.0. The effect of competing metals (Ca, Fe(III), and Zn) on ligand-induced U mobilization depended on the particular metal-ligand combination ranging from nearly complete U mobilization inhibition (e.g., Ca-citrate) to no apparent inhibitory effects or acceleration of U mobilization (e.g., Fe(III)-citrate). Humic substances (Suwannee River humic acid and fulvic acid) were tested across a range of concentrations either separately or combined with the aforementioned ligands. Humic substances alone mobilized appreciable U and also enhanced U mobilization in the presence of anthropogenic or biogenic ligands. These findings illustrate the complex influence of competing metals and humic substances on U mobilization by anthropogenic and biogenic ligands in the environment.
Collapse
Affiliation(s)
- Kyle J. Chardi
- Centre
for Microbiology and Environmental Systems Science, Department for
Environmental Geosciences, University of
Vienna, Josef-Holaubek-Platz 2 1090 Vienna, Austria
| | - Walter D. C. Schenkeveld
- Soil
Chemistry and Chemical Soil Quality Group, Wageningen University and Research, Droevendaalsesteeg 3, 6708 PB Wageningen, The Netherlands
| | - Naresh Kumar
- Soil
Chemistry and Chemical Soil Quality Group, Wageningen University and Research, Droevendaalsesteeg 3, 6708 PB Wageningen, The Netherlands
| | - Daniel E. Giammar
- Department
of Energy, Environmental, and Chemical Engineering, One Brookings
Drive, Washington University, St. Louis, Missouri 63130, United States
| | - Stephan M. Kraemer
- Centre
for Microbiology and Environmental Systems Science, Department for
Environmental Geosciences, University of
Vienna, Josef-Holaubek-Platz 2 1090 Vienna, Austria
| |
Collapse
|
4
|
Wasserman NL, Merino N, Coutelot F, Kaplan DI, Powell BA, Kersting AB, Zavarin M. Sources, seasonal cycling, and fate of plutonium in a seasonally stratified and radiologically contaminated pond. Sci Rep 2023; 13:11046. [PMID: 37422457 DOI: 10.1038/s41598-023-37276-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2023] [Accepted: 06/19/2023] [Indexed: 07/10/2023] Open
Abstract
Unlike short-term laboratory experiments, studies at sites historically contaminated with radionuclides can provide insight into contaminant migration behavior at environmentally-relevant decadal timescales. One such site is Pond B, a seasonally stratified reservoir within Savannah River Site (SC, USA) has low levels (μBq L-1) of plutonium in the water column. Here, we evaluate the origin of plutonium using high-precision isotope measurements, investigate the impact of water column geochemistry on plutonium cycling during different stratification periods, and re-evaluate long-term mass balance of plutonium in the pond. New isotopic data confirm that reactor-derived plutonium overwhelms input from Northern Hemisphere fallout at this site. Two suggested mechanisms for observed plutonium cycling in the water column include: (1) reductive dissolution of sediment-derived Fe(III)-(oxyhydr)oxides during seasonal stratification and (2) plutonium stabilization complexed strongly to Fe(III)-particulate organic matter (POM) complexes. While plutonium may be mobilized to a limited extent by stratification and reductive dissolution, peak plutonium concentrations are in shallow waters and associated with Fe(III)-POM at the inception of stratification. This suggests that plutonium release from sediments during stratification is not the dominant mechanism driving plutonium cycling in the pond. Importantly, our analysis suggests that the majority is retained in shallow sediments and may become increasingly recalcitrant.
Collapse
Affiliation(s)
- Naomi L Wasserman
- Glenn T. Seaborg Institute, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Ave, L-231, Livermore, CA, 94550, USA.
| | - Nancy Merino
- Glenn T. Seaborg Institute, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Ave, L-231, Livermore, CA, 94550, USA.
| | - Fanny Coutelot
- Department of Environmental Engineering and Earth Sciences, Clemson University, Anderson, SC, 29625, USA
- Center for Nuclear Environmental Engineering Sciences and Radioactive Waste Management, Clemson University, Anderson, SC, 29625, USA
| | | | - Brian A Powell
- Department of Environmental Engineering and Earth Sciences, Clemson University, Anderson, SC, 29625, USA
- Center for Nuclear Environmental Engineering Sciences and Radioactive Waste Management, Clemson University, Anderson, SC, 29625, USA
- Savannah River National Laboratory, Aiken, SC, 29625, USA
| | - Annie B Kersting
- Glenn T. Seaborg Institute, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Ave, L-231, Livermore, CA, 94550, USA
| | - Mavrik Zavarin
- Glenn T. Seaborg Institute, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Ave, L-231, Livermore, CA, 94550, USA
| |
Collapse
|
5
|
Chen J, Wang C, Wu J, Tao S. Plutonium in sediments of the Eastern Guangdong coast-its sources and their contribution. MARINE POLLUTION BULLETIN 2023; 193:115222. [PMID: 37406399 DOI: 10.1016/j.marpolbul.2023.115222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 06/19/2023] [Accepted: 06/22/2023] [Indexed: 07/07/2023]
Abstract
The 239+240Pu activities and 240Pu/239Pu atom ratios of surface sediments from the Eastern Guangdong coast (EGDC) were determined by sector field ICP-MS in order to examine the sources of plutonium (Pu) and quantify their contributions. The 239+240Pu activities in the EGDC ranged from 0.113 to 0.451 Bq kg-1, with an average of 0.225 ± 0.090 Bq kg-1 (n = 17). Consistently high 240Pu/239Pu atom ratios, ranging from 0.218 to 0.274 (average = 0.254 ± 0.014, n = 17), indicate a non-global fallout Pu source in the EGDC. The horizontal distribution of the 240Pu/239Pu atom ratios in the EGDC sediment suggests the non-global fallout Pu is sourced from close-in fallout from the Pacific Proving Grounds (PPG). Using a simple two end-member mixing model, we calculated the relative proportions of Pu from the PPG and global fallout in the EGDC to be 57 ± 9 % and 43 ± 9 %, respectively. Moreover, from the well-defined relationship between 239+240Pu activity and total organic carbon content in sediments and a two end-member mixing model using δ13C, we further calculated the Terr-global fallout (riverine input) and Mar-global fallout (direct atmospheric deposition) to be 11 ± 2 % and 32 ± 6 %, respectively. Finally, from the activity levels and atom ratios of Pu isotopes in the EGDC, we established a baseline for future use in environmental risk assessment related to nuclear power plant operations.
Collapse
Affiliation(s)
- Jisheng Chen
- Guangdong Provincial Key Laboratory of Marine Disaster Prediction and Prevention & Institute of Marine Sciences, Shantou University, Shantou 515063, China
| | - Cui Wang
- Third Institute of Oceanography, Ministry of Natural Resource, Xiamen 361005, China
| | - Junwen Wu
- Guangdong Provincial Key Laboratory of Marine Disaster Prediction and Prevention & Institute of Marine Sciences, Shantou University, Shantou 515063, China; Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou 511458, China.
| | - Shuqin Tao
- Third Institute of Oceanography, Ministry of Natural Resource, Xiamen 361005, China
| |
Collapse
|
6
|
Zhang D, Diao X, Wang Y, Xu K, Jin Q, Chen Z, Guo Z. Effect of Si content, pH, electrolyte and fulvic acid on the stability of Th(IV)-silicate colloids. J Radioanal Nucl Chem 2022. [DOI: 10.1007/s10967-022-08703-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
|
7
|
Gerber E, Romanchuk AY, Weiss S, Kuzenkova A, Hunault MOJY, Bauters S, Egorov A, Butorin SM, Kalmykov SN, Kvashnina KO. To form or not to form: PuO 2 nanoparticles at acidic pH. ENVIRONMENTAL SCIENCE. NANO 2022; 9:1509-1518. [PMID: 35520632 PMCID: PMC9009106 DOI: 10.1039/d1en00666e] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 02/08/2022] [Indexed: 11/25/2022]
Abstract
The aim of this study is to synthesize PuO2 nanoparticles (NPs) at low pH values and characterize the materials using laboratory and synchrotron-based methods. Properties of the PuO2 NPs formed under acidic conditions (pH 1-4) are explored here at the atomic scale. High-resolution transmission electron microscopy (HRTEM) is applied to characterize the crystallinity, morphology and size of the particles. It is found that 2 nm crystalline NPs are formed with a PuO2 crystal structure. High energy resolution fluorescence detected (HERFD) X-ray absorption spectroscopy at the Pu M4 edge has been used to identify the Pu oxidation states and recorded data are analysed using the theory based on the Anderson impurity model (AIM). The experimental data obtained on NPs show that the Pu(iv) oxidation state dominates in all NPs formed at pH 1-4. However, the suspension at pH 1 demonstrates the presence of Pu(iii) and Pu(vi) in addition to the Pu(iv), which is associated with redox dissolution of PuO2 NPs under acidic conditions. We discuss in detail the mechanism that affects the PuO2 NPs synthesis under acidic conditions and compare it with one in neutral and alkaline conditions. Hence, the results shown here, together with the first Pu M4 HERFD data on PuF3 and PuF4 compounds, are significant for the colloid facilitated transport governing the migration of plutonium in a subsurface environment.
Collapse
Affiliation(s)
- Evgeny Gerber
- Lomonosov Moscow State University, Department of Chemistry 119991 Moscow Russia
- The Rossendorf Beamline at ESRF - The European Synchrotron CS40220 38043 Grenoble Cedex 9 France
- Helmholtz Zentrum Dresden-Rossendorf (HZDR), Institute of Resource Ecology PO Box 510119 01314 Dresden Germany
| | - Anna Yu Romanchuk
- Lomonosov Moscow State University, Department of Chemistry 119991 Moscow Russia
| | - Stephan Weiss
- Helmholtz Zentrum Dresden-Rossendorf (HZDR), Institute of Resource Ecology PO Box 510119 01314 Dresden Germany
| | | | | | - Stephen Bauters
- The Rossendorf Beamline at ESRF - The European Synchrotron CS40220 38043 Grenoble Cedex 9 France
- Helmholtz Zentrum Dresden-Rossendorf (HZDR), Institute of Resource Ecology PO Box 510119 01314 Dresden Germany
| | - Alexander Egorov
- Lomonosov Moscow State University, Department of Chemistry 119991 Moscow Russia
| | - Sergei M Butorin
- Condensed Matter Physics of Energy Materials, X-ray Photon Science, Department of Physics and Astronomy, Uppsala University P.O. Box 516 SE-751 20 Uppsala Uppsala Sweden
| | - Stepan N Kalmykov
- Lomonosov Moscow State University, Department of Chemistry 119991 Moscow Russia
| | - Kristina O Kvashnina
- Lomonosov Moscow State University, Department of Chemistry 119991 Moscow Russia
- The Rossendorf Beamline at ESRF - The European Synchrotron CS40220 38043 Grenoble Cedex 9 France
- Helmholtz Zentrum Dresden-Rossendorf (HZDR), Institute of Resource Ecology PO Box 510119 01314 Dresden Germany
| |
Collapse
|
8
|
Deblonde GJP, Mattocks JA, Wang H, Gale EM, Kersting AB, Zavarin M, Cotruvo JA. Characterization of Americium and Curium Complexes with the Protein Lanmodulin: A Potential Macromolecular Mechanism for Actinide Mobility in the Environment. J Am Chem Soc 2021; 143:15769-15783. [PMID: 34542285 DOI: 10.1021/jacs.1c07103] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Anthropogenic radionuclides, including long-lived heavy actinides such as americium and curium, represent the primary long-term challenge for management of nuclear waste. The potential release of these wastes into the environment necessitates understanding their interactions with biogeochemical compounds present in nature. Here, we characterize the interactions between the heavy actinides, Am3+ and Cm3+, and the natural lanthanide-binding protein, lanmodulin (LanM). LanM is produced abundantly by methylotrophic bacteria, including Methylorubrum extorquens, that are widespread in the environment. We determine the first stability constant for an Am3+-protein complex (Am3LanM) and confirm the results with Cm3LanM, indicating a ∼5-fold higher affinity than that for lanthanides with most similar ionic radius, Nd3+ and Sm3+, and making LanM the strongest known heavy actinide-binding protein. The protein's high selectivity over 243Am's daughter nuclide 239Np enables lab-scale actinide-actinide separations as well as provides insight into potential protein-driven mobilization for these actinides in the environment. The luminescence properties of the Cm3+-LanM complex, and NMR studies of Gd3+-LanM, reveal that lanmodulin-bound f-elements possess two coordinated solvent molecules across a range of metal ionic radii. Finally, we show under a wide range of environmentally relevant conditions that lanmodulin effectively outcompetes desferrioxamine B, a hydroxamate siderophore previously proposed to be important in trivalent actinide mobility. These results suggest that natural lanthanide-binding proteins such as lanmodulin may play important roles in speciation and mobility of actinides in the environment; it also suggests that protein-based biotechnologies may provide a new frontier in actinide remediation, detection, and separations.
Collapse
Affiliation(s)
- Gauthier J-P Deblonde
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, United States.,Glenn T. Seaborg Institute, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
| | - Joseph A Mattocks
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Huan Wang
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital/Harvard Medical School, 149 Thirteenth Street, Charlestown, Massachusetts 02129, United States
| | - Eric M Gale
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital/Harvard Medical School, 149 Thirteenth Street, Charlestown, Massachusetts 02129, United States
| | - Annie B Kersting
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, United States.,Glenn T. Seaborg Institute, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
| | - Mavrik Zavarin
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, United States.,Glenn T. Seaborg Institute, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
| | - Joseph A Cotruvo
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| |
Collapse
|
9
|
Février L, Coppin F, Pierrisnard S, Bourdillon M, Nguyen LV, Zaiter N, Brandès S, Sladkov V, Chambron JC, Meyer M. Efficiency of dihydroxamic and trihydroxamic siderochelates to extract uranium and plutonium from contaminated soils. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2021; 235-236:106645. [PMID: 34020181 DOI: 10.1016/j.jenvrad.2021.106645] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 04/30/2021] [Accepted: 05/05/2021] [Indexed: 05/29/2023]
Abstract
Actinide-based mineral phases occurring in contaminated soils can be solubilized by organic chelators excreted by plants, such as citrate. Herein, the efficiency of citrate towards U and Pu extraction is compared to that of siderophores, whose primary function is the acquisition of iron(III) as an essential nutrient and growth factor for many soil microorganisms. To that end, we selected desferrioxamine B (DFB) as an emblematic bacterial trishydroxamic siderophore and a synthetic analog, abbreviated (LCy,Pr)H2, of the tetradentate rhodotorulic acid (RA) produced by yeasts. Firstly, the uranyl speciation with both ligands was assessed in the pH range 2-11 by potentiometry and visible absorption spectrophotometry. Equilibrium constants and absorption spectra for three [UO2(DFB)Hh](h-1)+ (h = 1-3) and five [UO2(LCy,Pr)lHh](2+h-2l)+ (-1 ≤ h ≤ 1 for l = 1 and h = 0-1 for l = 2) solution complexes were determined at 25.0 °C and I = 0.1 M KNO3. Similar studies for the Fe3+/(LCy,Pr)2- system revealed the formation of five species having [Fe(LCy,Pr)]+, [Fe(LCy,Pr)OH], [Fe(LCy,Pr)(OH)2]-, [Fe(LCy,Pr)2H], and [Fe2(LCy,Pr)3] compositions. Then, the ability of DFB, (LCy,Pr)H2, and citrate to solubilize either U or Pu from pitchblende-rich soils (soils 1 and 2) or freshly plutonium-contaminated soils (LBS and PG) was evaluated by performing batch extraction tests. U was extracted significantly only by citrate after a day. After one week, the amount of U complexed by citrate only slightly exceeded that measured for the siderochelates, following the order citrate > (LCy,Pr)H2 ≥ DFB ≈ H2O, and were comparatively very low. Pu was also more efficiently extracted by citrate than by DFB after a day, but only by a factor of ~2-3 for the PG soil, while the Pu concentration in the supernatant after one week was approximately the same for both natural chelators. It remained nearly constant for DFB between the 1st and 7th day, but drastically decreased in the case of citrate, suggesting chemical decomposition in the latter case. For the Fe-rich soils 1 and 2, the efficiencies of the three chelators to solubilize Fe after a day were of the same order of magnitude, decreasing in the order DFB > citrate > (LCy,Pr)H2. However, after a week DFB had extracted ~1.5 times more Fe, whereas the amount extracted by the other chelators stayed constant. For the less Fe-rich LBS and PG soils contaminated by Pu, the amounts of extracted Fe were higher, especially after 7 days, and the DFB outperformed citrate by a factor of nearly 3. The higher capacity of the hexadentate DFB to extract Pu in the presence of Fe and its lower ability to mobilize U qualitatively agree with the respective complexation constant ratios, keeping in mind that both Pu-containing soils had a lower iron loading. Noticeably, (LCy,Pr)H2 has roughly the same capacity as DFB to solubilize U, but it mobilizes less Fe than the hexadentate siderophore. Similarly, citrate has the highest capacity to extract Pu, but the lowest to extract Fe. Therefore, compared to DFB, (LCy,Pr)H2 shows a better U/Fe extraction selectivity and citrate shows a better Pu/Fe selectivity.
Collapse
Affiliation(s)
- Laureline Février
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSE-ENV/SRTE/LR2T, BP 3, 13115, Saint-Paul-Lez-Durance Cedex, France.
| | - Frédéric Coppin
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSE-ENV/SRTE/LR2T, BP 3, 13115, Saint-Paul-Lez-Durance Cedex, France
| | - Sylvie Pierrisnard
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSE-ENV/SRTE/LR2T, BP 3, 13115, Saint-Paul-Lez-Durance Cedex, France
| | - Mélanie Bourdillon
- Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB), UMR 6302, CNRS, Université Bourgogne-Franche-Comté, 9 avenue Alain Savary, BP 47870, 21078, Dijon Cedex, France
| | - Lé Vi Nguyen
- Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB), UMR 6302, CNRS, Université Bourgogne-Franche-Comté, 9 avenue Alain Savary, BP 47870, 21078, Dijon Cedex, France
| | - Nissrine Zaiter
- Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB), UMR 6302, CNRS, Université Bourgogne-Franche-Comté, 9 avenue Alain Savary, BP 47870, 21078, Dijon Cedex, France
| | - Stéphane Brandès
- Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB), UMR 6302, CNRS, Université Bourgogne-Franche-Comté, 9 avenue Alain Savary, BP 47870, 21078, Dijon Cedex, France
| | - Vladimir Sladkov
- Laboratoire de Physique des 2 Infinis Irène Joliot Curie (IJCLab), UMR 9012, CNRS/IN2P3 Université Paris-Saclay, Université de Paris, 15 rue Georges Clemenceau, 91405, Orsay, France
| | - Jean-Claude Chambron
- Institut de Chimie de Strasbourg, UMR 7177, CNRS, Université de Strasbourg, 1 rue Blaise Pascal, BP 296 R 8, 67008, Strasbourg Cedex, France
| | - Michel Meyer
- Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB), UMR 6302, CNRS, Université Bourgogne-Franche-Comté, 9 avenue Alain Savary, BP 47870, 21078, Dijon Cedex, France.
| |
Collapse
|
10
|
Cook M, Etschmann B, Ram R, Ignatyev K, Gervinskas G, Conradson SD, Cumberland S, Wong VNL, Brugger J. The nature of Pu-bearing particles from the Maralinga nuclear testing site, Australia. Sci Rep 2021; 11:10698. [PMID: 34021195 PMCID: PMC8139974 DOI: 10.1038/s41598-021-89757-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Accepted: 04/20/2021] [Indexed: 11/15/2022] Open
Abstract
The high-energy release of plutonium (Pu) and uranium (U) during the Maralinga nuclear trials (1955–1963) in Australia, designed to simulate high temperature, non-critical nuclear accidents, resulted in wide dispersion µm-sized, radioactive, Pu–U-bearing ‘hot’ particles that persist in soils. By combining non-destructive, multi-technique synchrotron-based micro-characterization with the first nano-scale imagining of the composition and textures of six Maralinga particles, we find that all particles display intricate physical and chemical make-ups consistent with formation via condensation and cooling of polymetallic melts (immiscible Fe–Al–Pu–U; and Pb ± Pu–U) within the detonation plumes. Plutonium and U are present predominantly in micro- to nano-particulate forms, and most hot particles contain low valence Pu–U–C compounds; these chemically reactive phases are protected by their inclusion in metallic alloys. Plutonium reworking was observed within an oxidised rim in a Pb-rich particle; however overall Pu remained immobile in the studied particles, while small-scale oxidation and mobility of U is widespread. It is notoriously difficult to predict the long-term environmental behaviour of hot particles. Nano-scale characterization of the hot particles suggests that long-term, slow release of Pu from the hot particles may take place via a range of chemical and physical processes, likely contributing to on-going Pu uptake by wildlife at Maralinga.
Collapse
Affiliation(s)
- Megan Cook
- School of Earth, Atmosphere and Environment, Monash University, Clayton, Australia
| | - Barbara Etschmann
- School of Earth, Atmosphere and Environment, Monash University, Clayton, Australia.
| | - Rahul Ram
- School of Earth, Atmosphere and Environment, Monash University, Clayton, Australia
| | - Konstantin Ignatyev
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxon, OX11 0QX, United Kingdom
| | - Gediminas Gervinskas
- Ramaciotti Centre for Cryo-Electron Microscopy, Monash University, Clayton, Australia
| | - Steven D Conradson
- Department of Chemistry, Washington State University, Pullman, WA, USA.,Department of Complex Matter, Josef Stefan Institute, Ljubljana, Slovenia
| | | | - Vanessa N L Wong
- School of Earth, Atmosphere and Environment, Monash University, Clayton, Australia
| | - Joёl Brugger
- School of Earth, Atmosphere and Environment, Monash University, Clayton, Australia.
| |
Collapse
|
11
|
Gerber E, Romanchuk AY, Pidchenko I, Amidani L, Rossberg A, Hennig C, Vaughan GBM, Trigub A, Egorova T, Bauters S, Plakhova T, Hunault MOJY, Weiss S, Butorin SM, Scheinost AC, Kalmykov SN, Kvashnina KO. The missing pieces of the PuO 2 nanoparticle puzzle. NANOSCALE 2020; 12:18039-18048. [PMID: 32648876 DOI: 10.1039/d0nr03767b] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The nanoscience field often produces results more mystifying than any other discipline. It has been argued that changes in the plutonium dioxide (PuO2) particle size from bulk to nano can have a drastic effect on PuO2 properties. Here we report a full characterization of PuO2 nanoparticles (NPs) at the atomic level and probe their local and electronic structures by a variety of methods available at the synchrotron, including extended X-ray absorption fine structure (EXAFS) at the Pu L3 edge, X-ray absorption near edge structure (XANES) in high energy resolution fluorescence detection (HERFD) mode at the Pu L3 and M4 edges, high energy X-ray scattering (HEXS) and X-ray diffraction (XRD). The particles were synthesized from precursors with different oxidation states of plutonium (III, IV, and V) under various environmentally and waste storage relevant conditions (pH 8 and pH > 10). Our experimental results analyzed with state-of-the-art theoretical approaches demonstrate that well dispersed, crystalline NPs with a size of ∼2.5 nm in diameter are always formed in spite of diverse chemical conditions. Identical crystal structures and the presence of only the Pu(iv) oxidation state in all NPs, reported here for the first time, indicate that the structure of PuO2 NPs is very similar to that of the bulk PuO2. All methods give complementary information and show that investigated fundamental properties of PuO2 NPs, rather than being exotic, are very similar to those of the bulk PuO2.
Collapse
Affiliation(s)
- Evgeny Gerber
- The Rossendorf Beamline at ESRF - The European Synchrotron, CS40220, 38043 Grenoble Cedex 9, France.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Guan Y, Mai J, Xu J, Liu Z. Characteristic of Pu from urban wetland and lacustrine sediments in Suzhou Industrial Park, China. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2020; 213:106134. [PMID: 31983444 DOI: 10.1016/j.jenvrad.2019.106134] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2019] [Revised: 12/02/2019] [Accepted: 12/09/2019] [Indexed: 06/10/2023]
Abstract
In this study, plutonium activity concentrations in the urban wetlands and lacustrine sediment of Suzhou Industrial Park (SIP) are studied for the first time. Results show 239+240Pu activity concentrations in the wetland surface soils of SIP range from 0.035 to 0.426 mBq/g and the 240Pu/239Pu atom ratio ranges from 0.171±0.024 to 0.226±0.049. Judging from the atom ratio of 240Pu/239Pu, the main source of Pu in the wetland is global fallout. The correlations of Pu between organic matter and heavy metals are also studied. The correlation coefficients show Pu has significant positive correlations with Cu, Sn and Pb but negative correlation with As. Unlike distributions of Pu in other places, Pu in SIP has weak correlation with organic matter content. A sediment core from Lake Yangcheng is also analyzed to investigate the historical record of Pu deposition. The atom ratios of each layer in the sediment core indicate the area is mainly influenced by global fallout. Using Pu as a discrete-time maker, the deposition rate in Lake Yangcheng is 0.396±0.019 cm/yr. The calculated inventory of 239+240Pu is 58.5 Bq/m2, which is in the range of inventories of the corresponding latitudes according to UNSCEAR.
Collapse
Affiliation(s)
- Yongjin Guan
- Guangxi Key Laboratory for Relativistic Astrophysics, School of Physical Science and Technology, Guangxi University, Nanning, 530004, China
| | - Jingyu Mai
- Guangxi Key Laboratory for Relativistic Astrophysics, School of Physical Science and Technology, Guangxi University, Nanning, 530004, China; State Key Laboratory of Radiation Medicine and Protection, School for Radiological and Interdisciplinary Sciences (RAD-X) and Collaborative Innovation Centre of Radiation Medicine of Jiangsu Higher Education Institutions, Soochow University, Suzhou, 215123, China
| | - Jiawei Xu
- State Key Laboratory of Radiation Medicine and Protection, School for Radiological and Interdisciplinary Sciences (RAD-X) and Collaborative Innovation Centre of Radiation Medicine of Jiangsu Higher Education Institutions, Soochow University, Suzhou, 215123, China
| | - Zhiyong Liu
- State Key Laboratory of Radiation Medicine and Protection, School for Radiological and Interdisciplinary Sciences (RAD-X) and Collaborative Innovation Centre of Radiation Medicine of Jiangsu Higher Education Institutions, Soochow University, Suzhou, 215123, China.
| |
Collapse
|
13
|
Wang R, Fu Y, Lei L, Li G, Liu Z. Distribution and Source Identification of Pu in River Basins in Southern China. ACS OMEGA 2019; 4:22646-22654. [PMID: 31909349 PMCID: PMC6941367 DOI: 10.1021/acsomega.9b03650] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 12/09/2019] [Indexed: 05/26/2023]
Abstract
The 239+240Pu activities and 240Pu/239Pu atom ratios in surface sediments from the major river basins in southern China were analyzed to investigate the distribution and source of Pu. We clarified that the 239+240Pu activities in these river basins were very similar, however, only the 239+240Pu activities in the Jinjiang Basin were generally higher than other samples. Because of river transport function, the distribution of 239+240Pu activities in these river basins presented an increasing trend from the upstream region to the estuary. According to the 240Pu/239Pu atom ratios, the Pu source in the inner river basins might be from global fallout, and the Pu in river estuaries might be from the global fallout and the Pacific Proving Grounds (PPG) in the Marshall Islands. Using a mass balance of the Pu model, we quantified in the Pearl River Estuary and the Pu contribution from the Pearl River Basin to Pu inventory was 13 ± 5%. These data not only filled in a knowledge gap of Pu in these river basins but also served as background data for Pu contamination from a nuclear reactor. Also, there are several planned and operating nuclear power plants in these river basins and these data could provide some indications for dealing with nuclear accidents in different parts of river basins in the future. In this study, we also analyzed some factors that would affect the distribution of 239+240Pu activities; however, only total organic carbon (TOC) content and the heavy metal As had a positive correlation with the 239+240Pu activity.
Collapse
Affiliation(s)
- Ruirui Wang
- State
Key Laboratory of Radiation Medicine and Protection, School for Radiological
and Interdisciplinary Sciences (RAD-X) and Collaborative Innovation
Centre of Radiation Medicine of Jiangsu Higher Education Institutions, Soochow University, Suzhou 215123, China
| | - Yao Fu
- State
Key Laboratory of Radiation Medicine and Protection, School for Radiological
and Interdisciplinary Sciences (RAD-X) and Collaborative Innovation
Centre of Radiation Medicine of Jiangsu Higher Education Institutions, Soochow University, Suzhou 215123, China
| | - Ling Lei
- State
Key Laboratory of Radiation Medicine and Protection, School for Radiological
and Interdisciplinary Sciences (RAD-X) and Collaborative Innovation
Centre of Radiation Medicine of Jiangsu Higher Education Institutions, Soochow University, Suzhou 215123, China
| | - Gang Li
- Key
Laboratory of Ocean and Marginal Sea Geology, South China Sea Institute
of Oceanology, Chinese Academy of Sciences, Guangzhou 510300, China
| | - Zhiyong Liu
- State
Key Laboratory of Radiation Medicine and Protection, School for Radiological
and Interdisciplinary Sciences (RAD-X) and Collaborative Innovation
Centre of Radiation Medicine of Jiangsu Higher Education Institutions, Soochow University, Suzhou 215123, China
| |
Collapse
|
14
|
Kvashnina KO, Romanchuk AY, Pidchenko I, Amidani L, Gerber E, Trigub A, Rossberg A, Weiss S, Popa K, Walter O, Caciuffo R, Scheinost AC, Butorin SM, Kalmykov SN. A Novel Metastable Pentavalent Plutonium Solid Phase on the Pathway from Aqueous Plutonium(VI) to PuO
2
Nanoparticles. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201911637] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Kristina O. Kvashnina
- Institute of Resource EcologyHelmholtz Zentrum Dresden-Rossendorf (HZDR) PO Box 510119 01314 Dresden Germany
- The Rossendorf Beamline at ESRFThe European Synchrotron, CS40220 38043 Grenoble Cedex 9 France
| | - Anna Yu. Romanchuk
- Department of ChemistryLomonosov Moscow State University 119991 Moscow Russia
| | - Ivan Pidchenko
- Institute of Resource EcologyHelmholtz Zentrum Dresden-Rossendorf (HZDR) PO Box 510119 01314 Dresden Germany
- The Rossendorf Beamline at ESRFThe European Synchrotron, CS40220 38043 Grenoble Cedex 9 France
| | - Lucia Amidani
- Institute of Resource EcologyHelmholtz Zentrum Dresden-Rossendorf (HZDR) PO Box 510119 01314 Dresden Germany
- The Rossendorf Beamline at ESRFThe European Synchrotron, CS40220 38043 Grenoble Cedex 9 France
| | - Evgeny Gerber
- Institute of Resource EcologyHelmholtz Zentrum Dresden-Rossendorf (HZDR) PO Box 510119 01314 Dresden Germany
- The Rossendorf Beamline at ESRFThe European Synchrotron, CS40220 38043 Grenoble Cedex 9 France
- Department of ChemistryLomonosov Moscow State University 119991 Moscow Russia
| | - Alexander Trigub
- National Research Centre “Kurchatov Institute” 123182 Moscow Russia
| | - Andre Rossberg
- Institute of Resource EcologyHelmholtz Zentrum Dresden-Rossendorf (HZDR) PO Box 510119 01314 Dresden Germany
- The Rossendorf Beamline at ESRFThe European Synchrotron, CS40220 38043 Grenoble Cedex 9 France
| | - Stephan Weiss
- The Rossendorf Beamline at ESRFThe European Synchrotron, CS40220 38043 Grenoble Cedex 9 France
| | - Karin Popa
- Directorate for Nuclear Safety and SecurityEuropean Commission, Joint Research Centre Postfach 2340 76215 Karlsruhe Germany
| | - Olaf Walter
- Directorate for Nuclear Safety and SecurityEuropean Commission, Joint Research Centre Postfach 2340 76215 Karlsruhe Germany
| | - Roberto Caciuffo
- Directorate for Nuclear Safety and SecurityEuropean Commission, Joint Research Centre Postfach 2340 76215 Karlsruhe Germany
| | - Andreas C. Scheinost
- Institute of Resource EcologyHelmholtz Zentrum Dresden-Rossendorf (HZDR) PO Box 510119 01314 Dresden Germany
- The Rossendorf Beamline at ESRFThe European Synchrotron, CS40220 38043 Grenoble Cedex 9 France
| | - Sergei M. Butorin
- Department of Physics and AstronomyMolecular and Condensed Matter PhysicsUppsala University P.O. Box 516 Uppsala Sweden
| | - Stepan N. Kalmykov
- Department of ChemistryLomonosov Moscow State University 119991 Moscow Russia
- National Research Centre “Kurchatov Institute” 123182 Moscow Russia
| |
Collapse
|
15
|
Kvashnina KO, Romanchuk AY, Pidchenko I, Amidani L, Gerber E, Trigub A, Rossberg A, Weiss S, Popa K, Walter O, Caciuffo R, Scheinost AC, Butorin SM, Kalmykov SN. A Novel Metastable Pentavalent Plutonium Solid Phase on the Pathway from Aqueous Plutonium(VI) to PuO 2 Nanoparticles. Angew Chem Int Ed Engl 2019; 58:17558-17562. [PMID: 31621992 PMCID: PMC6900038 DOI: 10.1002/anie.201911637] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Indexed: 11/10/2022]
Abstract
Here we provide evidence that the formation of PuO2 nanoparticles from oxidized PuVI under alkaline conditions proceeds through the formation of an intermediate PuV solid phase, similar to NH4PuO2CO3, which is stable over a period of several months. For the first time, state‐of‐the‐art experiments at Pu M4 and at L3 absorption edges combined with theoretical calculations unambiguously allow to determine the oxidation state and the local structure of this intermediate phase.
Collapse
Affiliation(s)
- Kristina O Kvashnina
- Institute of Resource Ecology, Helmholtz Zentrum Dresden-Rossendorf (HZDR), PO Box 510119, 01314, Dresden, Germany.,The Rossendorf Beamline at ESRF, The European Synchrotron, CS40220, 38043, Grenoble Cedex 9, France
| | - Anna Yu Romanchuk
- Department of Chemistry, Lomonosov Moscow State University, 119991, Moscow, Russia
| | - Ivan Pidchenko
- Institute of Resource Ecology, Helmholtz Zentrum Dresden-Rossendorf (HZDR), PO Box 510119, 01314, Dresden, Germany.,The Rossendorf Beamline at ESRF, The European Synchrotron, CS40220, 38043, Grenoble Cedex 9, France
| | - Lucia Amidani
- Institute of Resource Ecology, Helmholtz Zentrum Dresden-Rossendorf (HZDR), PO Box 510119, 01314, Dresden, Germany.,The Rossendorf Beamline at ESRF, The European Synchrotron, CS40220, 38043, Grenoble Cedex 9, France
| | - Evgeny Gerber
- Institute of Resource Ecology, Helmholtz Zentrum Dresden-Rossendorf (HZDR), PO Box 510119, 01314, Dresden, Germany.,The Rossendorf Beamline at ESRF, The European Synchrotron, CS40220, 38043, Grenoble Cedex 9, France.,Department of Chemistry, Lomonosov Moscow State University, 119991, Moscow, Russia
| | - Alexander Trigub
- National Research Centre "Kurchatov Institute", 123182, Moscow, Russia
| | - Andre Rossberg
- Institute of Resource Ecology, Helmholtz Zentrum Dresden-Rossendorf (HZDR), PO Box 510119, 01314, Dresden, Germany.,The Rossendorf Beamline at ESRF, The European Synchrotron, CS40220, 38043, Grenoble Cedex 9, France
| | - Stephan Weiss
- The Rossendorf Beamline at ESRF, The European Synchrotron, CS40220, 38043, Grenoble Cedex 9, France
| | - Karin Popa
- Directorate for Nuclear Safety and Security, European Commission, Joint Research Centre, Postfach 2340, 76215, Karlsruhe, Germany
| | - Olaf Walter
- Directorate for Nuclear Safety and Security, European Commission, Joint Research Centre, Postfach 2340, 76215, Karlsruhe, Germany
| | - Roberto Caciuffo
- Directorate for Nuclear Safety and Security, European Commission, Joint Research Centre, Postfach 2340, 76215, Karlsruhe, Germany
| | - Andreas C Scheinost
- Institute of Resource Ecology, Helmholtz Zentrum Dresden-Rossendorf (HZDR), PO Box 510119, 01314, Dresden, Germany.,The Rossendorf Beamline at ESRF, The European Synchrotron, CS40220, 38043, Grenoble Cedex 9, France
| | - Sergei M Butorin
- Department of Physics and Astronomy, Molecular and Condensed Matter Physics, Uppsala University, P.O. Box 516, Uppsala, Sweden
| | - Stepan N Kalmykov
- Department of Chemistry, Lomonosov Moscow State University, 119991, Moscow, Russia.,National Research Centre "Kurchatov Institute", 123182, Moscow, Russia
| |
Collapse
|
16
|
Lin P, Xu C, Kaplan DI, Chen H, Yeager CM, Xing W, Sun L, Schwehr KA, Yamazaki H, Saito-Kokubu Y, Hatcher PG, Santschi PH. Nagasaki sediments reveal that long-term fate of plutonium is controlled by select organic matter moieties. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 678:409-418. [PMID: 31077919 DOI: 10.1016/j.scitotenv.2019.04.375] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 04/23/2019] [Accepted: 04/25/2019] [Indexed: 06/09/2023]
Abstract
Forecasting the long-term fate of plutonium (Pu) is becoming increasingly important as more worldwide military and nuclear-power waste is being generated. Nagasaki sediments containing bomb-derived Pu that was deposited in 1945 provided a unique opportunity to explore the long-term geochemical behavior of Pu. Through a combination of selective extractions and molecular characterization via electrospray ionization Fourier-transform ion cyclotron resonance mass spectrometry (ESI-FTICRMS), we determined that 55 ± 3% of the bomb-derived 239,240Pu was preferentially associated with more persistent organic matter compounds in Nagasaki sediments, particularly those natural organic matter (NOM) stabilized by Fe oxides (NOMFe-oxide). Other organic matter compounds served as a secondary sink of these bomb-derived 239,240Pu (31 ± 2% on average), and <20% of the 239,240Pu was immobilized by inorganic mineral particles. In a narrow, 239,240Pu-enriched layer of only 9-cm depth (total core depth was 600 cm), N-containing carboxyl aliphatic and/or alicyclic molecules (CCAM) in NOMFe-oxide and other NOM fractions immobilized the majority of 239,240Pu. Among the cluster of N-containing CCAM moieties, hydroxamate siderophores, the strongest known Pu chelators in nature, were further detected in these "aged" Nagasaki bomb residue-containing sediments. While present long-term disposal and environmental remediation modeling assume that solubility limits and sorption to mineral surfaces control Pu subsurface mobility, our observations suggest that NOM, which is present in essentially all subsurface systems, undoubtedly plays an important role in sequestrering Pu. Ignoring the role of NOM in controlling Pu fate and transport is not justified in most environmental systems.
Collapse
Affiliation(s)
- Peng Lin
- Department of Marine Science, Texas A&M University at Galveston, Galveston, TX 77553, United States.
| | - Chen Xu
- Department of Marine Science, Texas A&M University at Galveston, Galveston, TX 77553, United States
| | - Daniel I Kaplan
- Savannah River National Laboratory, Aiken, SC 29808, United States
| | - Hongmei Chen
- Department of Chemistry and Biochemistry, College of Sciences, Old Dominion University, Norfolk, VA 23529, United States
| | - Chris M Yeager
- Los Alamos National Laboratory, Los Alamos, NM 87545, United States
| | - Wei Xing
- Department of Marine Science, Texas A&M University at Galveston, Galveston, TX 77553, United States
| | - Luni Sun
- Department of Marine Science, Texas A&M University at Galveston, Galveston, TX 77553, United States
| | - Kathleen A Schwehr
- Department of Marine Science, Texas A&M University at Galveston, Galveston, TX 77553, United States
| | - Hideo Yamazaki
- Formally from Kindai University, Higashi-osaka, Osaka Prefecture 577-8502, Japan
| | - Yoko Saito-Kokubu
- Tono Geoscience Center, Japan Atomic Energy Agency, Jorinji, Izumicho, Toki-Shi, Gifu Prefecture 509-5102, Japan
| | - Patrick G Hatcher
- Department of Chemistry and Biochemistry, College of Sciences, Old Dominion University, Norfolk, VA 23529, United States
| | - Peter H Santschi
- Department of Marine Science, Texas A&M University at Galveston, Galveston, TX 77553, United States
| |
Collapse
|
17
|
Götzke L, Schaper G, März J, Kaden P, Huittinen N, Stumpf T, Kammerlander KK, Brunner E, Hahn P, Mehnert A, Kersting B, Henle T, Lindoy LF, Zanoni G, Weigand JJ. Coordination chemistry of f-block metal ions with ligands bearing bio-relevant functional groups. Coord Chem Rev 2019. [DOI: 10.1016/j.ccr.2019.01.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
|
18
|
Lin P, Xu C, Zhang S, Fujitake N, Kaplan DI, Yeager CM, Sugiyama Y, Schwehr KA, Santschi PH. Plutonium Partitioning Behavior to Humic Acids from Widely Varying Soils Is Related to Carboxyl-Containing Organic Compounds. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:11742-11751. [PMID: 28933160 DOI: 10.1021/acs.est.7b03409] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In order to examine the influence of the HA molecular composition on the partitioning of Pu, ten different kinds of humic acids (HAs) of contrasting chemical composition, collected and extracted from different soil types around the world were equilibrated with groundwater at low Pu concentrations (10-14 M). Under mildly acidic conditions (pH ∼ 5.5), 29 ± 24% of the HAs were released as colloidal organic matter (>3 kDa to <0.45 μm), yet this HA fraction accounted for a vast majority of the bound Pu, 76 ± 13% on average. In comparison, the particulate HA fraction bound only 8 ± 4% on average of the added Pu. The truly dissolved Pu fraction was typically <1%. Pu binding was strongly and positively correlated with the concentrations of organic nitrogen in both particulate (>0.45 μm) and colloidal phases in terms of activity percentage and partitioning coefficient values (logKd). Based on molecular characterization of the HAs by solid state 13C nuclear magnetic resonance (NMR) and elemental analysis, Pu binding was correlated to the concentration of carboxylate functionalities and nitrogen groups in the particulate and colloidal phases. The much greater tendency of Pu to bind to colloidal HAs than to particulate HA has implications on whether NOM acts as a Pu source or sink during natural or man-induced episodic flooding.
Collapse
Affiliation(s)
- Peng Lin
- Department of Marine Science, Texas A & M University at Galveston , Galveston, Texas 77553, United States
| | - Chen Xu
- Department of Marine Science, Texas A & M University at Galveston , Galveston, Texas 77553, United States
| | - Saijin Zhang
- Department of Marine Science, Texas A & M University at Galveston , Galveston, Texas 77553, United States
| | - Nobuhide Fujitake
- Division of Agroenvironmental Biology, Graduate School of Agriculture Science, Kobe University , Kyoto, 606-8501, Japan
| | - Daniel I Kaplan
- Savannah River National Laboratory , Aiken, South Carolina 29808, United States
| | - Chris M Yeager
- Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - Yuko Sugiyama
- School of Human Science and Environment, University of Hyogo , 1-1-12 Shinzaike-Honcho, Himeji, Hyogo 670-0092, Japan
| | - Kathleen A Schwehr
- Department of Marine Science, Texas A & M University at Galveston , Galveston, Texas 77553, United States
| | - Peter H Santschi
- Department of Marine Science, Texas A & M University at Galveston , Galveston, Texas 77553, United States
| |
Collapse
|
19
|
DiDonato N, Xu C, Santschi PH, Hatcher PG. Substructural Components of Organic Colloids from a Pu-Polluted Soil with Implications for Pu Mobilization. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:4803-4811. [PMID: 28333454 DOI: 10.1021/acs.est.6b04955] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Contaminated soil organic matter from the Rocky Flats Environmental Technology Site (RFETS) has been previously shown to accumulate plutonium (Pu) in a colloidal subfraction and is hypothesized to contain cutin-like chemical structures cross-linked with hydroxamate functionality. The present study further characterizes this high Pu affinity subfraction using electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICRMS) and discovers additional substructural components. The Pu-enriched fraction was extracted and purified through a series of ultrafiltration and isoelectric focusing (IEF) electrophoresis steps. Predominantly low H/C and high double-bond equivalence (DBE) aromatic and condensed aromatic molecular formulas were detected, 66% of which are included in a COO Kendrick mass defect (KMD) homologous series. This suggests the existence of polycarboxylated aromatic and condensed aromatic formulas, with CHON-type COO KMD formulas relatively more abundant in the purified subfraction where Pu had been observed than in the crude soil fractions which had successively lower Pu concentrations. Nitrogen contents increased with the progression of purification (bulk soil → crude colloid → IEF colloid) and coincided with the trend of Pu concentration; thus, we propose that these nitrogen and carboxyl functionalities of aromatic compounds may also impart significant Pu chelation character to the colloid.
Collapse
Affiliation(s)
- Nicole DiDonato
- Department of Chemistry and Biochemistry, Old Dominion University , Norfolk, Virginia 23529, United States
| | - Chen Xu
- Department of Marine Sciences, Texas A&M University , Building 3029, Galveston, Texas 77553, United States
| | - Peter H Santschi
- Department of Marine Sciences, Texas A&M University , Building 3029, Galveston, Texas 77553, United States
| | - Patrick G Hatcher
- Department of Chemistry and Biochemistry, Old Dominion University , Norfolk, Virginia 23529, United States
| |
Collapse
|
20
|
Santschi PH, Xu C, Zhang S, Schwehr KA, Lin P, Yeager CM, Kaplan DI. Recent advances in the detection of specific natural organic compounds as carriers for radionuclides in soil and water environments, with examples of radioiodine and plutonium. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2017; 171:226-233. [PMID: 28286302 DOI: 10.1016/j.jenvrad.2017.02.023] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 02/25/2017] [Accepted: 02/26/2017] [Indexed: 06/06/2023]
Abstract
Among the key environmental factors influencing the fate and transport of radionuclides in the environment is natural organic matter (NOM). While this has been known for decades, there still remains great uncertainty in predicting NOM-radionuclide interactions because of lack of understanding of radionuclide interactions with the specific organic moieties within NOM. Furthermore, radionuclide-NOM studies conducted using modelled organic compounds or elevated radionuclide concentrations provide compromised information related to true environmental conditions. Thus, sensitive techniques are required not only for the detection of radionuclides, and their different species, at ambient and/or far-field concentrations, but also for potential trace organic compounds that are chemically binding these radionuclides. GC-MS and AMS techniques developed in our lab are reviewed here that aim to assess how two radionuclides, iodine and plutonium, form strong bonds with NOM by entirely different mechanisms; iodine tends to bind to aromatic functionalities, whereas plutonium binds to N-containing hydroxamate siderophores at ambient concentrations. While low-level measurements are a prerequisite for assessing iodine and plutonium migration at nuclear waste sites and as environmental tracers, it is necessary to determine their in-situ speciation, which ultimately controls their mobility and transport in natural environments. More importantly, advanced molecular-level instrumentation (e.g., nuclear magnetic resonance (NMR) and Fourier-transform ion cyclotron resonance coupled with electrospray ionization (ESI-FTICRMS) were applied to resolve either directly or indirectly the molecular environments in which the radionuclides are associated with the NOM.
Collapse
Affiliation(s)
| | - C Xu
- Texas A&M-Galveston, Galveston, TX, USA
| | - S Zhang
- Texas A&M-Galveston, Galveston, TX, USA
| | | | - P Lin
- Texas A&M-Galveston, Galveston, TX, USA
| | - C M Yeager
- Los Alamos National Laboratory, Los Alamos, NM, USA
| | - D I Kaplan
- Savannah River National Laboratory, Aiken, SC, USA
| |
Collapse
|
21
|
Emerson HP, Hickok KA, Powell BA. Experimental evidence for ternary colloid-facilitated transport of Th(IV) with hematite (α-Fe 2O 3) colloids and Suwannee River fulvic acid. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2016; 165:168-181. [PMID: 27723529 DOI: 10.1016/j.jenvrad.2016.10.001] [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: 06/10/2016] [Revised: 09/29/2016] [Accepted: 10/01/2016] [Indexed: 06/06/2023]
Abstract
Previous field experiments have suggested colloid-facilitated transport via inorganic and organic colloids as the primary mechanism of enhanced actinide transport in the subsurface at former nuclear weapons facilities. In this work, research was guided by the hypothesis that humic substances can enhance tetravalent actinide (An(IV)) migration by coating and mobilizing natural colloids in environmental systems and increasing An(IV) sorption to colloids. This mechanism is expected to occur under relatively acidic conditions where organic matter can sorb and coat colloid surfaces and facilitate formation of ternary colloid-ligand-actinide complexes. The objective of this work was to examine Th transport through packed columns in the presence of hematite colloids and/or Suwannee River fulvic acid (SRFA). In the presence of SRFA, with or without hematite colloids, significant transport (>60% recovery within the effluent) of thorium occurred through quartz columns. It is notable that the SRFA contributed to increased transport of both Th and hematite colloids, while insignificant transport occurred in the absence of fulvic acid. Further, in the presence of a natural sandy sediment (as opposed to pure quartz), transport is negligible in the presence of SRFA due to interactions with natural, clay-sized sediment coatings. Moreover, this data shows that the transport of Th through quartz columns is enhanced in ternary Th-colloid-SRFA and binary Th-SRFA systems as compared to a system containing only Th.
Collapse
Affiliation(s)
- Hilary P Emerson
- Clemson University, Department of Environmental Engineering and Earth Sciences, 342 Computer Court, Anderson, SC 29625, United States.
| | - Katherine A Hickok
- Clemson University, Department of Environmental Engineering and Earth Sciences, 342 Computer Court, Anderson, SC 29625, United States
| | - Brian A Powell
- Clemson University, Department of Environmental Engineering and Earth Sciences, 342 Computer Court, Anderson, SC 29625, United States.
| |
Collapse
|
22
|
Xu C, Zhang S, Sugiyama Y, Ohte N, Ho YF, Fujitake N, Kaplan DI, Yeager CM, Schwehr K, Santschi PH. Role of natural organic matter on iodine and (239)(,240)Pu distribution and mobility in environmental samples from the northwestern Fukushima Prefecture, Japan. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2016; 153:156-166. [PMID: 26773510 DOI: 10.1016/j.jenvrad.2015.12.022] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Revised: 12/23/2015] [Accepted: 12/27/2015] [Indexed: 06/05/2023]
Abstract
In order to assess how environmental factors are affecting the distribution and migration of radioiodine and plutonium that were emitted from the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident, we quantified iodine and (239,240)Pu concentration changes in soil samples with different land uses (urban, paddy, deciduous forest and coniferous forest), as well as iodine speciation in surface water and rainwater. Sampling locations were 53-63 km northwest of the FDNPP within a 75-km radius, in close proximity of each other. A ranking of the land uses by their surface soil (<4 cm) stable (127)I concentrations was coniferous forest > deciduous forest > urban > paddy, and (239,240)Pu concentrations ranked as deciduous forest > coniferous forest > paddy ≥ urban. Both were quite distinct from that of (134)Cs and (137)Cs: urban > coniferous forest > deciduous forest > paddy, indicating differences in their sources, deposition phases, and biogeochemical behavior in these soil systems. Although stable (127)I might not have fully equilibrated with Fukushima-derived (129)I, it likely still works as a proxy for the long-term fate of (129)I. Surficial soil (127)I content was well correlated to soil organic matter (SOM) content, regardless of land use type, suggesting that SOM might be an important factor affecting iodine biogeochemistry. Other soil chemical properties, such as Eh and pH, had strong correlations to soil (127)I content, but only within a given land use (e.g., within urban soils). Organic carbon (OC) concentrations and Eh were positively, and pH was negatively correlated to (127)I concentrations in surface water and rain samples. It is also noticeable that (127)I in the wet deposition was concentrated in both the deciduous and coniferous forest throughfall and stemfall water, respectively, comparing to the bulk rainwater. Further, both forest throughfall and stemflow water consisted exclusively of organo-iodine, suggesting all inorganic iodine in the original bulk deposition (∼ 28.6% of total iodine) have been completely converted to organo-iodine. Fukushima-derived (239,240)Pu was detectable at a distance ∼ 61 km away, NW of FDNPP. However, it is confined to the litter layer, even three years after the FDNPP accident-derived emissions. Plutonium-239,240 activities were significantly correlated with soil OC and nitrogen contents, indicating Pu may be associated with nitrogen-containing SOM, similar to what has been observed at other locations in the United States. Together, these finding suggest that natural organic matter (NOM) plays a key role in affecting the fate and transport of I and Pu and may warrant greater consideration for predicting long-term stewardship of contaminated areas and evaluating various remediation options in Japan.
Collapse
Affiliation(s)
- Chen Xu
- Laboratory for Environmental and Oceanographic Research, Department of Marine Sciences, Texas A&M University, Building 3029, Galveston, TX, 77551, USA.
| | - Saijin Zhang
- Laboratory for Environmental and Oceanographic Research, Department of Marine Sciences, Texas A&M University, Building 3029, Galveston, TX, 77551, USA
| | - Yuko Sugiyama
- School of Human Science and Environment, University of Hyogo, 1-1-12 Shinzaike-Honcho, Himeji, Hyogo, 670-0092, Japan
| | - Nobuhito Ohte
- Department of Social Informatics, Graduate School of Informatics, Kyoto University, Kyoto, 606-8501, Japan
| | - Yi-Fang Ho
- Laboratory for Environmental and Oceanographic Research, Department of Marine Sciences, Texas A&M University, Building 3029, Galveston, TX, 77551, USA
| | - Nobuhide Fujitake
- Division of Agroenvironmental Biology, Graduate School of Agriculture Science, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe, 657-8501, Japan
| | | | - Chris M Yeager
- Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Kathleen Schwehr
- Laboratory for Environmental and Oceanographic Research, Department of Marine Sciences, Texas A&M University, Building 3029, Galveston, TX, 77551, USA
| | - Peter H Santschi
- Laboratory for Environmental and Oceanographic Research, Department of Marine Sciences, Texas A&M University, Building 3029, Galveston, TX, 77551, USA
| |
Collapse
|
23
|
Francis AJ, Dodge CJ. Microbial mobilization of plutonium and other actinides from contaminated soil. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2015; 150:277-285. [PMID: 26406590 DOI: 10.1016/j.jenvrad.2015.08.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Revised: 08/17/2015] [Accepted: 08/24/2015] [Indexed: 06/05/2023]
Abstract
We examined the dissolution of Pu, U, and Am in contaminated soil from the Nevada Test Site (NTS) due to indigenous microbial activity. Scanning transmission x-ray microscopy (STXM) analysis of the soil showed that Pu was present in its polymeric form and associated with Fe- and Mn- oxides and aluminosilicates. Uranium analysis by x-ray diffraction (μ-XRD) revealed discrete U-containing mineral phases, viz., schoepite, sharpite, and liebigite; synchrotron x-ray fluorescence (μ-XRF) mapping showed its association with Fe- and Ca-phases; and μ-x-ray absorption near edge structure (μ-XANES) confirmed U(IV) and U(VI) oxidation states. Addition of citric acid or glucose to the soil and incubated under aerobic or anaerobic conditions enhanced indigenous microbial activity and the dissolution of Pu. Detectable amount of Am and no U was observed in solution. In the citric acid-amended sample, Pu concentration increased with time and decreased to below detection levels when the citric acid was completely consumed. In contrast, with glucose amendment, Pu remained in solution. Pu speciation studies suggest that it exists in mixed oxidation states (III/IV) in a polymeric form as colloids. Although Pu(IV) is the most prevalent and generally considered to be more stable chemical form in the environment, our findings suggest that under the appropriate conditions, microbial activity could affect its solubility and long-term stability in contaminated environments.
Collapse
Affiliation(s)
- A J Francis
- Biological, Environmental & Climate Sciences Department, Brookhaven National Laboratory, Upton, NY 11973, USA.
| | - C J Dodge
- Biological, Environmental & Climate Sciences Department, Brookhaven National Laboratory, Upton, NY 11973, USA
| |
Collapse
|
24
|
Xu C, Zhang S, Kaplan DI, Ho YF, Schwehr KA, Roberts KA, Chen H, DiDonato N, Athon M, Hatcher PG, Santschi PH. Evidence for Hydroxamate Siderophores and Other N-Containing Organic Compounds Controlling (239,240)Pu Immobilization and Remobilization in a Wetland Sediment. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:11458-67. [PMID: 26313339 DOI: 10.1021/acs.est.5b02310] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Pu concentrations in wetland surface sediments collected downstream of a former nuclear processing facility in F-Area of the Savannah River Site (SRS), USA, were ∼2.5 times greater than those measured in the associated upland aquifer sediments; similarly, the Pu concentration solid/water ratios were orders of magnitude greater in the wetland than in the low-organic matter content aquifer soils. Sediment Pu concentrations were correlated to total organic carbon and total nitrogen contents and even more strongly to hydroxamate siderophore (HS) concentrations. The HS were detected in the particulate or colloidal phases of the sediments but not in the low molecular weight fractions (<1000 Da). Macromolecules which scavenged the majority of the potentially mobile Pu were further separated from the bulk mobile organic matter fraction ("water extract") via an isoelectric focusing experiment (IEF). An electrospray ionization Fourier-transform ion cyclotron resonance ultrahigh resolution mass spectrometry (ESI FTICR-MS) spectral comparison of the IEF extract and a siderophore standard (desferrioxamine; DFO) suggested the presence of HS functionalities in the IEF extract. This study suggests that while HS are a very minor component in the sediment particulate/colloidal fractions, their concentrations greatly exceed those of ambient Pu, and HS may play an especially important role in Pu immobilization/remobilization in wetland sediments.
Collapse
Affiliation(s)
- Chen Xu
- Department of Marine Sciences, Texas A&M University , Building 3029, Galveston, Texas 77554, United States
| | - Saijin Zhang
- Department of Marine Sciences, Texas A&M University , Building 3029, Galveston, Texas 77554, United States
| | - Daniel I Kaplan
- Savannah River National Laboratory , Aiken, South Carolina 29808, United States
| | - Yi-Fang Ho
- Department of Marine Sciences, Texas A&M University , Building 3029, Galveston, Texas 77554, United States
| | - Kathleen A Schwehr
- Department of Marine Sciences, Texas A&M University , Building 3029, Galveston, Texas 77554, United States
| | - Kimberly A Roberts
- Savannah River National Laboratory , Aiken, South Carolina 29808, United States
| | - Hongmei Chen
- Department of Chemistry and Biochemistry, College of Sciences, Old Dominion University , Norfolk, Virginia 23529, United States
| | - Nicole DiDonato
- Department of Chemistry and Biochemistry, College of Sciences, Old Dominion University , Norfolk, Virginia 23529, United States
| | - Matthew Athon
- Department of Marine Sciences, Texas A&M University , Building 3029, Galveston, Texas 77554, United States
| | - Patrick G Hatcher
- Department of Chemistry and Biochemistry, College of Sciences, Old Dominion University , Norfolk, Virginia 23529, United States
| | - Peter H Santschi
- Department of Marine Sciences, Texas A&M University , Building 3029, Galveston, Texas 77554, United States
| |
Collapse
|
25
|
Harrington JM, Duckworth OW, Haselwandter K. The fate of siderophores: antagonistic environmental interactions in exudate-mediated micronutrient uptake. Biometals 2015; 28:461-72. [DOI: 10.1007/s10534-015-9821-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 01/07/2015] [Indexed: 11/25/2022]
|
26
|
Matsunaga T, Tsuduki K, Yanase N, Kritsananuwat R, Hanzawa Y, Naganawa H. Increase in rare earth element concentrations controlled by dissolved organic matter in river water during rainfall events in a temperate, small forested catchment. J NUCL SCI TECHNOL 2014. [DOI: 10.1080/00223131.2014.961989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
|
27
|
Duckworth OW, Akafia MM, Andrews MY, Bargar JR. Siderophore-promoted dissolution of chromium from hydroxide minerals. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2014; 16:1348-1359. [PMID: 24683601 DOI: 10.1039/c3em00717k] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Biomolecules have significant impacts on the fate and transport of contaminant metals in soils and natural waters. Siderophores, Fe(iii)-binding agents that are exuded by microbes and plants, may form strong complexes with and promote the dissolution of contaminant metal ions, such as Co(iii), U(iv), or Pu(iv). Although aqueous Cr(iii)-siderophore complexes have been recognized in the laboratory setting for almost 40 years, few studies have explored interactions of siderophores with Cr-bearing minerals or considered their impacts on environmental chemistry. To better understand the possible effects of siderophores on chromium mobility, we conducted a series of dissolution experiments to quantify the dissolution rates of Cr(iii)(OH)3 in the presence of hydroxamate, catecholate, and α-hydroxycarboxylate siderophores over a range of environmentally relevant pH values. At pH = 5, dissolution rates in the presence of siderophores are similar to control experiments, suggesting a predominantly proton-promoted dissolution mechanism. At pH = 8, the sorption of the siderophores desferrioxamine B and rhizoferrin can be modeled by using Langmuir isotherms. The dissolution rates for these siderophores are proportional to the surface concentrations of sorbed siderophore, and extended X-ray absorption fine structure spectra of dissolution products indicates the formation of Cr(iii)HDFOB(+) and Cr(iii)rhizoferrin(3-) complexes, suggesting a ligand-promoted dissolution mechanism at alkaline pH. Because siderophores promote Cr(iii)(OH)3 dissolution at rates similar in magnitude to those of iron hydroxides and the resulting Cr(iii)-siderophore complexes may be persistent in solution, siderophores could potentially contribute to the mobilization of Cr in soils and sediments where it is abundant due to geological or anthropogenic sources.
Collapse
Affiliation(s)
- Owen W Duckworth
- Department of Soil Science, North Carolina State University, Raleigh, NC 27695-7619, USA.
| | | | | | | |
Collapse
|
28
|
Xu C, Athon M, Ho YF, Chang HS, Zhang S, Kaplan DI, Schwehr KA, DiDonato N, Hatcher PG, Santschi PH. Plutonium immobilization and remobilization by soil mineral and organic matter in the far-field of the Savannah River Site, U.S. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:3186-3195. [PMID: 24555528 DOI: 10.1021/es404951y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
To study the effects of natural organic matter (NOM) on Pu sorption, Pu(IV) and (V) were amended at environmentally relevant concentrations (10(-14) M) to two soils of contrasting particulate NOM concentrations collected from the F-Area of the Savannah River Site. More Pu(IV) than (V) was bound to soil colloidal organic matter (COM). A de-ashed humic acid (i.e., metals being removed) scavenged more Pu(IV,V) into its colloidal fraction than the original HA incorporated into its colloidal fraction, and an inverse trend was thus observed for the particulate-fraction-bound Pu for these two types of HAs. However, the overall Pu binding capacity of HA (particulate + colloidal-Pu) decreased after de-ashing. The presence of NOM in the F-Area soil did not enhance Pu fixation to the organic-rich soil when compared to the organic-poor soil or the mineral phase from the same soil source, due to the formation of COM-bound Pu. Most importantly, Pu uptake by organic-rich soil decreased with increasing pH because more NOM in the colloidal size desorbed from the particulate fraction in the elevated pH systems, resulting in greater amounts of Pu associated with the COM fraction. This is in contrast to previous observations with low-NOM sediments or minerals, which showed increased Pu uptake with increasing pH levels. This demonstrates that despite Pu immobilization by NOM, COM can convert Pu into a more mobile form.
Collapse
Affiliation(s)
- Chen Xu
- Department of Marine Sciences, Texas A&M University , Building 3029, Galveston, Texas 77553, United States
| | | | | | | | | | | | | | | | | | | |
Collapse
|
29
|
Shcherbina NS, Kalmykov SS, Karpiouk LA, Ponomarenko SA, Hatfield K, Haire R, Perminova IV. Nonreversible immobilization of water-borne plutonium onto self-assembled adlayers of silanized humic materials. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:2226-2233. [PMID: 24533599 DOI: 10.1021/es404583f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The objective was to study plutonium partitioning between immobile and mobile humic materials at the water-solid interfaces. Immobilization of the humic materials on solid supports was performed in situ using self-adhesive silanized humic derivatives. The presence of the humic adlayers on solid supports was shown to significantly enhance Pu sorption and its retention under both steady state and dynamic conditions. While plutonium may exist in multiple oxidations states plus colloidal forms, the major thrust in this work was to study the behavior of most mobile--the PuO2(+) form in dilute solutions. The values of the plutonium partition coefficients (Kd) between water and humics-coated silica gels after 10 days exposure reached 1.6 × 10(4) L · kg(-1) at pH 7.5 under anaerobic conditions with a total plutonium concentration of 1.2 × 10(-8) M exceeding those for the uncoated SiO2 (6.3 × 10(2) L · kg(-1)). Column tests showed substantial sequestration of water-borne plutonium (up to 73%) on the humics-coated silica gels. Remobilization experiments conducted under batch conditions at different pH values (3.5, 4.5, 7.5) showed that no more than 3% of the sequestered Pu was remobilized from the humics-coated silica gels by treatment with dissolved humic materials at environmentally relevant pH of 7.5. Consequently, silanized humic materialas can be seen as both molecular probes and as potent candidate materials for scavenging mobile Pu from an aqueous phase.
Collapse
Affiliation(s)
- Natalia S Shcherbina
- Department of Chemistry, Lomonosov Moscow State University , Leninskie Gory 1-3, Moscow 119991, Russia
| | | | | | | | | | | | | |
Collapse
|
30
|
Zänker H, Hennig C. Colloid-borne forms of tetravalent actinides: a brief review. JOURNAL OF CONTAMINANT HYDROLOGY 2014; 157:87-105. [PMID: 24365396 DOI: 10.1016/j.jconhyd.2013.11.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Revised: 11/08/2013] [Accepted: 11/26/2013] [Indexed: 06/03/2023]
Abstract
Tetravalent actinides, An(IV), are usually assumed to be little mobile in near-neutral environmental waters because of their low solubility. However, there are certain geochemical scenarios during which mobilization of An(IV) in a colloid-borne (waterborne) form cannot be ruled out. A compilation of colloid-borne forms of tetravalent actinides described so far for laboratory experiments together with several examples of An(IV) colloids observed in field experiments and real-world scenarios are given. They are intended to be a knowledge base and a tool for those who have to interpret actinide behavior under environmental conditions. Synthetic colloids containing structural An(IV) and synthetic colloids carrying adsorbed An(IV) are considered. Their behavior is compared with the behavior of An(IV) colloids observed after the intentional or unintentional release of actinides into the environment. A list of knowledge gaps as to the behavior of An(IV) colloids is provided and items which need further research are highlighted.
Collapse
Affiliation(s)
- Harald Zänker
- Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf, P.O. Box 51 01 19, D-01314 Dresden, Germany.
| | - Christoph Hennig
- Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf, P.O. Box 51 01 19, D-01314 Dresden, Germany
| |
Collapse
|
31
|
Kozai N, Ohnuki T, Iwatsuki T. Characterization of saline groundwater at Horonobe, Hokkaido, Japan by SEC-UV-ICP-MS: speciation of uranium and iodine. WATER RESEARCH 2013; 47:1570-1584. [PMID: 23295069 DOI: 10.1016/j.watres.2012.12.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Revised: 11/26/2012] [Accepted: 12/10/2012] [Indexed: 06/01/2023]
Abstract
The saline groundwater collected at a depth of about 500 m in Horonobe, Japan, where an underground research laboratory (URL) has been built, is rich in saline (Na 4900 ppm, Cl 7600 ppm), iodine (42 ppm), and methane gas. We analyzed the colloids and ions of this groundwater mainly by employing a size exclusion chromatography (SEC) coupled on-line to ultraviolet-visible (UV-Vis) detection and inductively coupled plasma mass spectrometry (ICP-MS) technique and focused on the speciation of uranium and iodine, both of which are of particular importance for radioactive waste disposal. For this purpose, the groundwater sample was introduced to SEC columns after being passed through a 0.45 μm filter but without further pretreatment, such as isolation of colloids. The chromatographic profiles obtained with two different SEC columns were compared. This study revealed that uranium present in the groundwater at several tens of ppt was associated with low molecular weight silica species with neutral charge. The silica species were virtually free of metal elements such as Na, K, Mg, Ca, and Al. This study also found that almost all of the iodine in the groundwater was iodide (I(-)). The groundwater contained an unidentified organic colloid that was not a carrier for the radioactive waste-relevant elements Se, Sr, I, Cs, Th, and U.
Collapse
Affiliation(s)
- Naofumi Kozai
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan.
| | | | | |
Collapse
|
32
|
Abstract
The recent estimated global stockpile of separated plutonium (Pu) worldwide is about 500 t, with equal contributions from nuclear weapons and civilian nuclear energy. Independent of the United States' future nuclear energy policy, the current large and increasing stockpile of Pu needs to be safely isolated from the biosphere and stored for thousands of years. Recent laboratory and field studies have demonstrated the ability of colloids (1-1000 nm particles) to facilitate the migration of strongly sorbing contaminants such as Pu. In understanding the dominant processes that may facilitate the transport of Pu, the initial source chemistry and groundwater chemistry are important factors, as no one process can explain all the different field observations of Pu transport. Very little is known about the molecular-scale geochemical and biochemical mechanisms controlling Pu transport, leaving our conceptual model incomplete. Equally uncertain are the conditions that inhibit the cycling and mobility of Pu in the subsurface. Without a better mechanistic understanding for Pu at the molecular level, we cannot advance our ability to model its transport behavior and achieve confidence in predicting long-term transport. Without a conceptual model that can successfully predict long-term Pu behavior and ultimately isolation from the biosphere, the public will remain skeptical that nuclear energy is a viable and an attractive alternative to counter global warming effects of carbon-based energy alternatives. This review summarizes our current understanding of the relevant conditions and processes controlling the behavior of Pu in the environment, gaps in our scientific knowledge, and future research needs.
Collapse
Affiliation(s)
- Annie B Kersting
- Glenn T. Seaborg Institute, Physical & Life Sciences, Lawrence Livermore National Laboratory, L-231, P.O. Box 808, Livermore, California 94550, USA.
| |
Collapse
|
33
|
Affiliation(s)
- Kate Maher
- Department of Geological & Environmental Sciences, Stanford University, Stanford, California 94305-2115, United States
| | | | - Gordon E. Brown
- Department of Geological & Environmental Sciences, Stanford University, Stanford, California 94305-2115, United States
| |
Collapse
|
34
|
Xu C, Miller EJ, Zhang S, Li HP, Ho YF, Schwehr KA, Kaplan DI, Otosaka S, Roberts KA, Brinkmeyer R, Yeager CM, Santschi PH. Sequestration and remobilization of radioiodine (129I) by soil organic matter and possible consequences of the remedial action at Savannah River Site. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2011; 45:9975-9983. [PMID: 22035296 DOI: 10.1021/es201343d] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
In order to investigate the distributions and speciation of (129)I (and (127)I) in a contaminated F-Area groundwater plume of the Savannah River Site that cannot be explained by simple transport models, soil resuspension experiments simulating surface runoff or stormflow and erosion events were conducted. Results showed that 72-77% of the newly introduced I(-) or IO(3)(-) were irreversibly sequestered into the organic-rich riparian soil, while the rest was transformed by the soil into colloidal and truly dissolved organo-iodine, resulting in (129)I remobilization from the soil greatly exceeding the 1 pCi/L drinking water permit. This contradicts the conventional view that only considers I(-) or IO(3)(-) as the mobile forms. Laboratory iodination experiments indicate that iodine likely covalently binds to aromatic structures of the soil organic matter (SOM). Under very acidic conditions, abiotic iodination of SOM was predominant, whereas under less acidic conditions (pH ≥5), microbial enzymatically assisted iodination of SOM was predominant. The organic-rich soil in the vadose zone of F-Area thus acts primarily as a "sink," but may also behave as a potentially important vector for mobile radioiodine in an on-off carrying mechanism. Generally the riparian zone provides as a natural attenuation zone that greatly reduces radioiodine release.
Collapse
Affiliation(s)
- Chen Xu
- Laboratory for Environmental and Oceanographic Research, Department of Marine Sciences, Texas A&M University, Building 3029, Galveston, Texas 77551, United States.
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
35
|
Caldwell E, Duff M, Ferguson C, Coughlin D. Plutonium uptake and behavior in vegetation of the desert southwest: a preliminary assessment. JOURNAL OF ENVIRONMENTAL MONITORING : JEM 2011; 13:2575-2581. [PMID: 21796316 DOI: 10.1039/c1em10208g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Eight species of desert vegetation and associated soils were collected from the Nevada National Security Site (N2S2) and analyzed for 238Pu and 239 + 240Pu concentrations. Amongst the plant species sampled were: atmospheric elemental accumulators (moss and lichen), the very slow growing, long-lived creosote bush and the rapidly growing, short-lived cheatgrass brome. The diversity of growth strategies provided insight into the geochemical behavior and bio-availability of Pu at the N2S2. The highest concentrations of Pu were measured in the onion moss (24.27 Bq kg-1 238Pu and 52.78 Bq kg-1 239 + 240Pu) followed by the rimmed navel lichen (8.18 Bq kg-1 and 18.4 Bq kg-1 respectively), pointing to the importance of eolian transport of Pu. Brome and desert globemallow accumulated between 3 and 9 times higher concentrations of Pu than creosote and sage brush species. These results support the importance of species specific elemental accumulation strategies rather than exposure duration as the dominant variable influencing Pu concentrations in these plants. Total vegetation elemental concentrations of Ce, Fe, Al, Sm and others were also analyzed. Strong correlations were observed between Fe and Pu. This supports the conclusion that Pu was accumulated as a consequence of the active accumulation of Fe and other plant required nutrients. Cerium and Pu are considered to be chemical analogs. Strong correlations observed in plants support the conclusion that these elements displayed similar geochemical behavior in the environment as it related to the biochemical uptake process of vegetation. Soils were also sampled in association with vegetation samples. This allowed for the calculation of a concentration ratio (CR). The CR values for Pu in plants were highly influenced by the heterogeneity of Pu distribution among sites. Results from the naturally occurring elements of concern were more evenly distributed between sample sites. This allowed for the development of a pattern of plant species that accumulated Ce, Sm, Fe and Al. The highest accumulators of these elements were onion moss, lichen flowed by brome. The lowest accumulators were creosote bush and fourwing saltbush. This ranked order corresponds to plant accumulations of Pu.
Collapse
Affiliation(s)
- Eric Caldwell
- Savannah River National Laboratory - Environmental Assessment, Building 773-42a Room 234, Aiken, South Carolina 29808, USA
| | | | | | | |
Collapse
|
36
|
Froidevaux P, Steinmann P, Pourcelot L. Long-term and long-range migration of radioactive fallout in a Karst system. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2010; 44:8479-8484. [PMID: 20977200 DOI: 10.1021/es100954h] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Mountainous areas are often covered by little evolved soils from which deposited radionuclides can potentially leak into the vadose zone. In the Swiss Jura mountains, we observed unusual isotopic ratios of nuclear weapon test (NWTs) fallout with an apparent loss of NWTs plutonium relative to ¹³⁷Cs of Chernobyl origin in thinner soils. Here, we studied the karstic watershed of a vauclusian spring to determine the residence times of plutonium, ²⁴¹Am, and ⁹⁰Sr deposited by global fallout and their respective mobility in carbonaceous soils. The results show that ⁹⁰Sr is washed most efficiently from the watershed with a residence time of several hundred years. The estimated plutonium residence time is more than 10 times higher (in the range of 5000-10,000 years), and the ²⁴¹Am residence time is double that of plutonium. The spring water ²⁴¹Am/²³⁹+²⁴⁰Pu isotopic ratio is lower (0.12 - 0.28) than found in watershed soils (0.382 ± 0.077). Similar differences are found in aquatic mosses (²⁴¹Am/²³⁹+²⁴⁰Pu isotopic ratio 0.05-0.12), which are permanently submerged in spring waters. In contrast to plutonium, ⁹⁰Sr is leached from these mosses with 0.5M HCl, demonstrating that strontium is probably associated with calcium carbonate precipitations on the mosses. The higher plutonium to americium isotopic ratio found in the samples of spring water and mosses at the outlet of the karst shows that plutonium mobility is enhanced.
Collapse
Affiliation(s)
- Pascal Froidevaux
- University Institute of Radiation Physics, University of Lausanne, University Hospital Center, Lausanne, Switzerland.
| | | | | |
Collapse
|
37
|
Chawla F, Steinmann P, Loizeau JL, Hassouna M, Froidevaux P. Binding of ²³⁹Pu and ⁹⁰Sr to organic colloids in soil solutions: evidence from a field experiment. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2010; 44:8509-8514. [PMID: 20964354 DOI: 10.1021/es101766g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Colloidal transport has been shown to enhance the migration of plutonium in groundwater downstream from contaminated sites, but little is known about the adsorption of ⁹⁰Sr and plutonium onto colloids in the soil solution of natural soils. We sampled soil solutions using suction cups, and separated colloids using ultrafiltration to determine the distribution of ²³⁹Pu and ⁹⁰Sr between the truly dissolved fraction and the colloidal fraction of the solutions of three Alpine soils contaminated only by global fallout from the nuclear weapon tests. Plutonium was essentially found in the colloidal fraction (>80%) and probably associated with organic matter. A significant amount of colloidal ⁹⁰Sr was detected in organic-rich soil solutions. Our results suggest that binding to organic colloids in the soil solutions plays a key role with respect to the mobility of plutonium in natural alpine soils and, to a lesser extent, to the mobility of ⁹⁰Sr.
Collapse
Affiliation(s)
- Fabienne Chawla
- Institute for Radiation Physics, University Hospital Center, and Institute of Mineralogy and Geochemistry, University of Lausanne, Switzerland
| | | | | | | | | |
Collapse
|
38
|
Xu C, Santschi PH, Schwehr KA, Hung CC. Optimized isolation procedure for obtaining strongly actinide binding exopolymeric substances (EPS) from two bacteria (Sagittula stellata and Pseudomonas fluorescens Biovar II). BIORESOURCE TECHNOLOGY 2009; 100:6010-6021. [PMID: 19574036 DOI: 10.1016/j.biortech.2009.06.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2008] [Revised: 09/09/2008] [Accepted: 06/02/2009] [Indexed: 05/28/2023]
Abstract
Different chemical extractants (NaCl, EDTA, HCl and NaOH) and physical methods (ultrasonication and heating) were examined by their efficacies of extracting "attached" exopolymeric substances (EPS) secreted by marine bacterium Sagittula stellata (SS) and terrestrial bacterium Pseudomonas fluorescens Biovar II (PF). Extraction by 0.5 N HCl for 3 h was best for SS while extraction by 0.05 N NaCl for 3-5 h was regarded as optimal for PF. Improvements in EPS purification included a pre-diafiltration step to remove the broth material and reduce the solution volume, thus the usage of ethanol, and time. The EPS harvested at the optimal time and purified by the improved method were enriched in polysaccharides, with smaller amounts of proteins, thus having amphiphilic properties. Isoelectric focusing of (234)Th or (240)Pu labeled EPS showed both actinides were strongly bound to macromolecules with low pI, similar to reported marine or soil colloidal natural organic matter (NOM).
Collapse
Affiliation(s)
- Chen Xu
- Laboratory for Oceanographic and Environmental Research, Departments of Oceanography and Marine Sciences, Texas A&M University, 5007 Avenue U, Galveston, TX 77551, United States.
| | | | | | | |
Collapse
|