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Vivas EL, Kim KW, Suh YJ, Cho K. Fiber support prevents colloid-facilitated contamination induced by dissolution-precipitation of a calcium phosphate adsorbent. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2023; 342:118345. [PMID: 37311347 DOI: 10.1016/j.jenvman.2023.118345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 05/25/2023] [Accepted: 06/06/2023] [Indexed: 06/15/2023]
Abstract
During the adsorptive removal of hazardous metal contaminants, dissolution-precipitation of sparingly soluble adsorbents may result in the formation of toxic colloidal suspensions, triggering secondary pollution. Therefore, we studied the prevention of colloid-facilitated contamination in a model adsorption system of dicalcium phosphate dihydrate (DCPD, CaHPO4·2H2O) and Cd2+ as an adsorbent and adsorbate. Upon adding pure DCPD powder into a 500 mg L-1 Cd2+ solution of pH ≌ 7.0, aggregates of spheroidal Cd-bearing primary particles, within 0.040-0.95 μm size range, were generated via dissolution-precipitation. The accumulated volume of these submicron particles (10.8%) was greater than that of the submicron particles from the exposure of DCPD to deionized water (4.48%). While the Cd-carrying submicron particles, which are responsible for colloidal recontamination, appeared to form via homogeneous nucleation, their formation was suppressed using polyacrylonitrile fibers (PANFs) as supporting substrates. Thus, heterogeneous nucleation on PANFs formed hexagonal columnar microparticles of a new phase, pentacadmium dihydrogen tetrakis (phosphate) tetrahydrate (Cd5H2(PO4)4·4H2O). Together with dissolution-precipitation on the native DCPD, nucleation and growth on the PANFs accelerated the depletion of the dissolved species, reducing the degree of supersaturation along the DCPD-water interface. Although the PANFs decreased the Cd adsorption capacity to 56.7% of that of DCPD, they prevented the formation of small aggregates of Cd-bearing particles. Other sparingly soluble adsorbents can be compounded with PANF to prevent the generation of toxic colloids.
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Affiliation(s)
- Eleazer L Vivas
- Department of Environmental Engineering, Pusan National University, 2 Busandaehak-ro 63beon-gil, Geumjeong-gu, Busan, 46241, Republic of Korea
| | - Keon-Woo Kim
- Department of Environmental Engineering, Pusan National University, 2 Busandaehak-ro 63beon-gil, Geumjeong-gu, Busan, 46241, Republic of Korea
| | - Yong Jae Suh
- Resources Utilization Division, Korea Institute of Geoscience and Mineral Resources, 124 Gwahak-ro, Yuseong-gu, Daejeon, 34132, Republic of Korea; Department of Resources Engineering, Korea University of Science and Technology, 217 Gajeong-ro, Yuseong-gu, Daejeon, 34113, Republic of Korea.
| | - Kuk Cho
- Department of Environmental Engineering, Pusan National University, 2 Busandaehak-ro 63beon-gil, Geumjeong-gu, Busan, 46241, Republic of Korea.
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Balboni E, Merino N, Begg JD, Samperton KM, Zengotita FE, Law GTW, Kersting AB, Zavarin M. Plutonium mobilization from contaminated estuarine sediments, Esk Estuary (UK). CHEMOSPHERE 2022; 308:136240. [PMID: 36057346 DOI: 10.1016/j.chemosphere.2022.136240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 08/24/2022] [Accepted: 08/25/2022] [Indexed: 06/15/2023]
Abstract
Since 1952, liquid radioactive effluent containing238-242Pu, 241Am, 237Np, 137Cs, and 99Tc has been released with authorization from the Sellafield nuclear complex (UK) into the Irish Sea. This represents the largest source of plutonium (Pu) discharged in all western Europe, with 276 kg having been released. In the Eastern Irish Sea, the majority of the transuranic activity has settled into an area of sediments (Mudpatch) located off the Cumbrian coast. Radionuclides from the Mudpatch have been re-dispersed via particulate transport in fine-grained estuarine and intertidal sediments to the North-East Irish Sea, including the intertidal saltmarsh located at the mouth of the Esk Estuary. Saltmarshes are highly dynamic systems which are vulnerable to external agents (sea level change, erosion, sediment supply, and freshwater inputs), and their stability remains uncertain under current sea level rise projections and possible increases in storm activity. In this work, we examined factors affecting Pu mobility in contaminated sediments collected from the Esk Estuary by conducting leaching experiments under both anoxic and oxic conditions. Leaching experiments were conducted over a 9-month period and were periodically sampled to determine solution phase Pu via multicollector-inductively coupled plasma-mass spectrometry (MC-ICP-MS), and to measure redox indicators (Eh, pH and extractable Fe(II)). Microbial community composition was also characterized in the sediments, and at the beginning and end of the anoxic/oxic experiments. Results show that: 1) Pu leaching is about three times greater in solutions leached under anoxic conditions compared to oxic conditions, 2) the sediment slurry microbial communities shift as conditions change from anoxic to oxic, 3) Pu leaching is enhanced in the shallow sediments (0-10 cm depth), and 4) the magnitude of Pu leached from sediments is not correlated with total Pu, indicating that the biogeochemistry of sediment-associated Pu is spatially heterogeneous. These findings provide constraints on the stability of redox sensitive Pu in biogeochemically dynamic/transient environments on a timescale of months and suggests that anoxic conditions can enhance Pu mobility in estuarine systems.
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Affiliation(s)
- Enrica Balboni
- Seaborg Institute, Lawrence Livermore National Laboratory, Livermore, CA, 94550, United States.
| | - Nancy Merino
- Seaborg Institute, Lawrence Livermore National Laboratory, Livermore, CA, 94550, United States
| | - James D Begg
- Seaborg Institute, Lawrence Livermore National Laboratory, Livermore, CA, 94550, United States; Amphos 21, Barcelona, Spain
| | - Kyle M Samperton
- Seaborg Institute, Lawrence Livermore National Laboratory, Livermore, CA, 94550, United States; Trace Nuclear Measurement Technology Group, Savannah River National Laboratory, Aiken, SC, 29808, United States
| | - Frances E Zengotita
- Seaborg Institute, Lawrence Livermore National Laboratory, Livermore, CA, 94550, United States; Department of Civil & Environmental Engineering & Earth Sciences, University of Notre Dame, Notre Dame, IN, 46556, United States
| | - Gareth T W Law
- Radiochemistry Unit, Department of Chemistry, University of Helsinki, Finland
| | - Annie B Kersting
- Seaborg Institute, Lawrence Livermore National Laboratory, Livermore, CA, 94550, United States
| | - Mavrik Zavarin
- Seaborg Institute, Lawrence Livermore National Laboratory, Livermore, CA, 94550, United States
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Han X, Zhu J, Zhu Y, Li G, Liu Z. 237Np and 241Am as Fingerprints in the Major River Basins of Southern China and North South China Sea: A Land-Sea Perspective. ACS OMEGA 2021; 6:26897-26909. [PMID: 34693111 PMCID: PMC8529606 DOI: 10.1021/acsomega.1c03152] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 09/30/2021] [Indexed: 05/25/2023]
Abstract
During the global nuclear weapon tests, large amounts of radioactive elements are released into the environment. Long-period actinide elements such as Np, Pu, and Am exhibit different behaviors in various environments, and their isotope characteristic fingerprints are of great significance for studying the distribution, migration, and prediction of radioactive pollutants. To investigate the distribution of 241Am and 237Np in southern China, activities of 241Am (0.008 ± 0.012-0.932 ± 0.066 Bq/kg) and 237Np (0.037 ± 0.003-1.458 ± 0.063 mBq/kg), 237Np/239Pu atom ratios (0.055 ± 0.003-0.864 ± 0.054), and 241Am/239+240Pu activity ratios (0.033 ± 0.075-15.870 ± 0.477) in 95 surface sediment samples collected from the northern South China Sea and major river basins were analyzed for the first time. Due to the different scavenging mechanisms of Am and Pu, 241Am is preferentially concentrated by sinking the particulate, while plutonium is scavenged in the coastal area, resulting in a higher 241Am/239+240Pu activity ratio in estuary and coastal areas. The distribution of 237Np shows obvious spatial inhomogeneity as the high migration rate. The relevant fingerprint characteristic has changed greatly and needs to be updated urgently. As a result of the convergence of land and sea, 241Am, 239,240Pu, and 237Np are dominated by terrestrial sediments and deposited in the coastal area of southern China, which should be paid more attention to. This work can establish China's current neptunium radioactivity database, and the difference in Np, Pu, and Am scavenging processes may be a powerful tool for evaluating the impact of the Pearl River Estuary salt tide.
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Affiliation(s)
- Xiaoxiao Han
- 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
| | - Jianjun Zhu
- Department
of Emergency and Critical Care Medicine, The Second Affiliated Hospital of Soochow University, Suzhou 215006, China
| | - Yawei Zhu
- 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
- 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
- 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
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Pan C, Jiao Y, Kersting AB, Zavarin M. Plutonium Redox Transformation in the Presence of Iron, Organic Matter, and Hydroxyl Radicals: Kinetics and Mechanistic Insights. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:1800-1810. [PMID: 33471518 DOI: 10.1021/acs.est.0c08195] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Plutonium (Pu) redox and complexation processes in the presence of natural organic matter and associated iron can impact the fate and transport of Pu in the environment. We studied the fate of Pu(IV) in the presence of humic acid (HA) and Fe(II) upon reaction with H2O2 that may be generated by photochemical and other reactions. A portion of Pu(IV) was oxidized to Pu(V/VI), which is primarily ascribed to the generation of reactive intermediates from the oxidation of Fe(II) and Fe(II)-HA complexes by H2O2. The kinetics of Pu(IV) oxidation is pH-dependent and can be described by a model that incorporates Pu redox kinetics with published HA-modified Fenton reaction kinetics. At pH 3.5, the presence of HA slowed Pu(IV) oxidation, while at pH 6, HA accelerated Pu(IV) oxidation in the first several hours followed by a reverse process where the oxidized Pu(V/VI) was reduced back to Pu(IV). Analysis of Pu-associated particle size suggests that Pu oxidation state is a major driver in its complexation with HA and formation of colloids and heteroaggregates. Our results revealed the H2O2-driven oxidation of Pu(IV)-HA-Fe(II) colloids with implications to the transient mobilization of Pu(V/VI) in organic-rich redox transition zones.
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Affiliation(s)
- Chao Pan
- Glenn T. Seaborg Institute, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, United States
| | - Yongqin Jiao
- Biosciences and Biotechnology Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, United States
| | - Annie B Kersting
- Glenn T. Seaborg Institute, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, United States
| | - Mavrik Zavarin
- Glenn T. Seaborg Institute, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, United States
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Romanchuk AY, Vlasova IE, Kalmykov SN. Speciation of Uranium and Plutonium From Nuclear Legacy Sites to the Environment: A Mini Review. Front Chem 2020; 8:630. [PMID: 32903456 PMCID: PMC7434977 DOI: 10.3389/fchem.2020.00630] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Accepted: 06/17/2020] [Indexed: 12/02/2022] Open
Abstract
The row of 15 chemical elements from Ac to Lr with atomic numbers from 89 to 103 are known as the actinides, which are all radioactive. Among them, uranium and plutonium are the most important as they are used in the nuclear fuel cycle and nuclear weapon production. Since the beginning of national nuclear programs and nuclear tests, many radioactively contaminated nuclear legacy sites, have been formed. This mini review covers the latest experimental, modeling, and case studies of plutonium and uranium migration in the environment, including the speciation of these elements and the chemical reactions that control their migration pathways.
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Affiliation(s)
| | | | - Stepan N. Kalmykov
- Department of Chemistry, Lomonosov Moscow State University, Moscow, Russia
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