1
|
Wu M, Shi Y, Liu Z, Pan S, Hou S, Gao J, Zhang S, Guo H. Provenance and sedimentation of Pu and 237Np in the northern Taiwan Strait suffering intensive land-ocean interaction. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2025; 366:125420. [PMID: 39615566 DOI: 10.1016/j.envpol.2024.125420] [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: 08/27/2024] [Revised: 11/04/2024] [Accepted: 11/28/2024] [Indexed: 01/26/2025]
Abstract
The China Sea is faced with a heightened risk of anthropogenic radionuclide contamination, whose provenance, scavenging and migration are imperative to investigate to provide the background and nuclear safety emergency assessment. This study pioneers the measurement of anthropogenic plutonium and neptunium (239+240Pu and 237Np) concentrations and atom ratios (240Pu/239Pu and 237Np/239Pu) in sediment cores from the northern Taiwan Strait and the adjacent East China Sea using SF-ICP-MS, exploring their applications and characteristics. Typical vertical profiles confirm that Pu and 237Np serve as geochronological tools, with the 240Pu/239Pu atom ratio as a fingerprint refining the chronology. Fallout history and sedimentary environments have been reconstructed by the comprehensive application of 239+240Pu, 237Np and 210Pb chronologies. The primary sources of Pu isotopes and 237Np are global fallout and close-in fallout from the Pacific Proving Grounds (PPG). Inventories of 239+240Pu ranged from 44 ± 3 Bq/m2 to 348 ± 11 Bq/m2, with PPG contributions from 57% to 72%, while 237Np inventories varied from 58 ± 5 mBq/m2 to 137 ± 8 mBq/m2. Differences in the distribution of Pu and 237Np are attributed to their distinct behaviors and sedimentary environments. Particle-reactive Pu isotopes are predominantly preserved in sediment, whereas conservative 237Np remains mostly dissolved in water, easily re-entering seawater from sediment through resuspension processes. Higher environmental mobility also makes more downward diffusion of 237Np than Pu isotopes.
Collapse
Affiliation(s)
- Mengmeng Wu
- The Key Laboratory of Coastal and Island Development of Ministry of Education, School of Geographic and Oceanographic Sciences, Nanjing University, Nanjing, 210023, China
| | - Yong Shi
- The Key Laboratory of Coastal and Island Development of Ministry of Education, School of Geographic and Oceanographic Sciences, Nanjing University, Nanjing, 210023, 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.
| | - Shaoming Pan
- The Key Laboratory of Coastal and Island Development of Ministry of Education, School of Geographic and Oceanographic Sciences, Nanjing University, Nanjing, 210023, China
| | - Shugui Hou
- The Key Laboratory of Coastal and Island Development of Ministry of Education, School of Geographic and Oceanographic Sciences, Nanjing University, Nanjing, 210023, China; School of Oceanography, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Jianhua Gao
- The Key Laboratory of Coastal and Island Development of Ministry of Education, School of Geographic and Oceanographic Sciences, Nanjing University, Nanjing, 210023, China
| | - Shuai Zhang
- The Key Laboratory of Coastal and Island Development of Ministry of Education, School of Geographic and Oceanographic Sciences, Nanjing University, Nanjing, 210023, China
| | - Haiting Guo
- The Key Laboratory of Coastal and Island Development of Ministry of Education, School of Geographic and Oceanographic Sciences, Nanjing University, Nanjing, 210023, China
| |
Collapse
|
2
|
Zhang S, Liu Z, Yang G, Zheng J, Pan S, Aono T, Sakaguchi A. Rapid Method To Determine 137Cs, 237Np, and Pu Isotopes in Seawater by SF-ICP-MS. Anal Chem 2023; 95:16892-16901. [PMID: 37906231 DOI: 10.1021/acs.analchem.3c02702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Abstract
Neptunium-237, owing to its long half-life (t1/2 = 2.14 × 106 year) and similar conservatism to 137Cs, has the potential to replace 137Cs for water mass circulation studies on decades and even longer time scales. A new method for the determination of 137Cs, 237Np, and Pu isotopes in seawater samples was proposed to solve the difficulty of 237Np analysis in seawater. The developed method includes the separation technique of ammonium phosphomolybdate (AMP) adsorption for 137Cs and anion exchange chromatography for 237Np and Pu, a measurement technique of gamma spectrometry for 137Cs and SF-ICP-MS for 237Np and Pu isotopes. 242Pu as a pseudo isotope dilution tracer for Np, the negligible chemical fractionation between 237Np and 242Pu of 1.02 ± 0.06 (k = 2) was obtained by implementing sophisticated control of the redox system and chromatographic elution optimization. The analytical results for the International Atomic Energy Agency Certified Reference Materials (IAEA-443) agreed with the reference values, showing chemical yields of 65-88%, U decontamination factor above 106 level, and improved sample throughput (5 days for 12 samples). Meanwhile, the lower method detection limits (MDLs) of 237Np, 239Pu, and 240Pu were 1.3 × 10-3, 0.065, and 0.15 μBq L-1 for 15 L seawater, respectively. Results obtained by the developed method can be used to evaluate the impact on the marine ecological system of the planned marine discharge of Fukushima decontaminated wastewater. Working toward that purpose, we are the first to report the 237Np activity concentration in Pacific Ocean seawater sampled near the station site, and we obtained the value of 0.122-0.154 μBq L-1.
Collapse
Affiliation(s)
- Shuai Zhang
- Institute of Radiological Sciences, National Institutes for Quantum Science and Technology, 4-9-1 Anagawa, Inage , Chiba 263-8555, Japan
- School of Geographic and Oceanographic Sciences, Nanjing University, Nanjing 210023, China
| | - Zhiyong Liu
- Institute of Radiological Sciences, National Institutes for Quantum Science and Technology, 4-9-1 Anagawa, Inage , Chiba 263-8555, Japan
- 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
| | - Guosheng Yang
- Institute of Radiological Sciences, National Institutes for Quantum Science and Technology, 4-9-1 Anagawa, Inage , Chiba 263-8555, Japan
| | - Jian Zheng
- Institute of Radiological Sciences, National Institutes for Quantum Science and Technology, 4-9-1 Anagawa, Inage , Chiba 263-8555, Japan
| | - Shaoming Pan
- School of Geographic and Oceanographic Sciences, Nanjing University, Nanjing 210023, China
| | - Tatsuo Aono
- Institute of Radiological Sciences, National Institutes for Quantum Science and Technology, 4-9-1 Anagawa, Inage , Chiba 263-8555, Japan
- Radioecology Unit, Fukushima Institute for Research, Education and Innovation, 1 Hikariga-oka, Fukushima, Fukushima 960-1295, Japan
| | - Aya Sakaguchi
- Institute of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba , Ibaraki 305-8577, Japan
| |
Collapse
|
3
|
Hong S, Um W. Decontamination of neutron-activated radioactive concrete waste by separating Eu, Co, Fe, and Mn-containing sand particles using dense medium separation. JOURNAL OF HAZARDOUS MATERIALS 2023; 443:130183. [PMID: 36272373 DOI: 10.1016/j.jhazmat.2022.130183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 10/05/2022] [Accepted: 10/10/2022] [Indexed: 06/16/2023]
Abstract
Neutron-activated concrete waste is one of the most challenging radioactive wastes to decontaminate because the radionuclides exist in a chemically stable binding state, and it is very difficult to break those bindings with the conventional acid decontamination method. Here, we suggest a new dense medium separation (DMS) of felsic and mafic minerals from simulated neutron-activated concrete waste using sodium-polytungstate (SPT) solution because most elements (Eu, Co, Fe, and Mn) that can be activated by neutrons are concentrated in mafic minerals. We also determined the optimal density of the SPT solution as ∼ 2.70 g/cm3, and a high degree of decontamination was achieved for sand particles ranging from 75 to 500 µm in size. Under these optimized conditions, DMS (80.02%) exhibits much higher radionuclide removal efficiency (RRE) than 5 M acid decontaminations (23.27-31.29%) for Eu. Furthermore, DMS (59.38-63.36%) shows similar RRE to 5 M acid decontaminations (41.67-73.94%) for Fe, Mn, and Co. We believe this DMS process could be useful and applicable to the decontamination of neutron-activated concrete wastes because it is possible to perform a large-scale process compared to conventional acid decontamination methods, which is also advantageous in reducing secondary waste generation and facile radionuclide recovery.
Collapse
Affiliation(s)
- Seokju Hong
- Division of Advanced Nuclear Engineering (DANE), Pohang University of Science and Technology (POSTECH), 77 Cheongam-ro, Nam-Gu, Pohang 790-784, Republic of Korea
| | - Wooyong Um
- Division of Advanced Nuclear Engineering (DANE), Pohang University of Science and Technology (POSTECH), 77 Cheongam-ro, Nam-Gu, Pohang 790-784, Republic of Korea; Division of Environmental Sciences and Engineering (DESE), Pohang University of Science and Technology (POSTECH), 77 Cheongam-ro, Nam-Gu, Pohang 790-784, Republic of Korea; Nuclear Environmental Technology Institute (NETI), Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk 790-784, Republic of Korea.
| |
Collapse
|
4
|
Fernandes BL, Alves GF, Lisboa TP, Lowinsohn D. A new eco-friendly strategy for chromium determination in stainless steels: Electrolytic dissolution followed by voltammetric detection. Microchem J 2022. [DOI: 10.1016/j.microc.2022.108042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|