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Journal Articles

Frontiers of studies utilizing accelerator mass spectrometry in geoscience

Honda, Maki

Journal of the Mass Spectrometry Society of Japan, 70(4), p.282 - 283, 2022/12

The development of measurement and chemical separation techniques in the accelerator mass spectrometry (AMS) method has enabled highly sensitive analysis of $$^{244}$$Pu (half-life 8.1$$times$$10$$^{7}$$ years), $$^{60}$$Fe (half-life 2.62$$times$$10$$^{6}$$ years), and $$^{90}$$Sr (half-life 28.9 years) in AMS. For example, the study analyzing $$^{244}$$Pu in ferromanganese crust samples successfully quantified $$^{244}$$Pu from outside the solar system, which had been hidden by $$^{244}$$Pu from nuclear tests. Furthermore, the research has revealed that $$^{244}$$Pu is produced in neutron star mergers, etc., leading to unraveling the production sites where the heavy elements originate. This topic highlights the frontline of studies on $$^{244}$$Pu, $$^{60}$$Fe, and $$^{90}$$Sr utilizing AMS.

Journal Articles

Challenging studies by accelerator mass spectrometry for the development of environmental radiology; Status report on the analysis of $$^{90}$$Sr and $$^{135}$$Cs by AMS

Honda, Maki; Martschini, M.*; Wieser, A.*; Marchhart, O.*; Lachner, J.*; Priller, A.*; Steier, P.*; Golser, R.*; Sakaguchi, Aya*

JAEA-Conf 2022-001, p.85 - 90, 2022/11

Accelerator mass spectrometry (AMS) is an analytical method that combines mass spectrometry with a tandem accelerator, which has been used mainly in nuclear physics experiments. AMS is used to measure radionuclides with half-lives of 10$$^{3}$$-10$$^{8}$$ years. For radionuclides with half-lives of this order, the method of measuring their mass is 10$$^{3}$$-10$$^{6}$$ times more sensitive than measuring their activity. Because of this advantage, AMS has been widely applied in Earth and planetary sciences, atomic energy research, and other fields. Among the various studies, Wallner et al. (2021, 2016) have achieved excellent work in Earth and planetary sciences. For example, they have attained the ultra-sensitive analysis of $$^{60}$$Fe and $$^{244}$$Pu in environmental samples. These are radionuclides produced by rapid-neutron-capture (r-process) nucleosynthesis. Our recent work shows that a new AMS system (VERA, University of Vienna), which combines laser isobaric separation and a typical AMS system, has been successfully applied to the ultra-sensitive determination of $$^{90}$$Sr and $$^{135}$$Cs in environment. For $$^{90}$$Sr in environmental samples, the $$beta$$-ray measurement by the milking of the daughter nuclide $$^{90}$$Y is still the principal method, which takes 3-6 weeks. The new AMS method has a detection limit of $$<$$ 0.1 mBq, which is comparable to that of $$beta$$-ray measurement, with a more straightforward chemical treatment than $$beta$$-measurement. Our achievement demonstrates that AMS can be a practical new method for determining $$^{90}$$Sr in the environment.

Journal Articles

Novel $$^{90}$$Sr analysis of environmental samples by ion-laser interaction mass spectrometry

Honda, Maki; Martschini, M.*; Marchhart, O.*; Priller, A.*; Steier, P.*; Golser, R.*; Sato, Tetsuya; Tsukada, Kazuaki; Sakaguchi, Aya*

Analytical Methods, 14(28), p.2732 - 2738, 2022/07

 Times Cited Count:2 Percentile:56.45(Chemistry, Analytical)

The sensitive $$^{90}$$Sr analysis with accelerator mass spectrometry (AMS) was developed for the advances of environmental radiology. One advantage of AMS is the ability to analyze various environmental samples with $$^{90}$$Sr/$$^{88}$$Sr atomic ratios of 10$$^{-14}$$ in a simple chemical separation. Three different IAEA samples with known $$^{90}$$Sr concentrations (moss-soil, animal bone, Syrian soil: 1 g each) were analyzed to assess the validity of the chemical separation and the AMS measurement. The $$^{90}$$Sr measurements were conducted on the AMS system combined with the Ion Laser InterAction MasSpectrometry (ILIAMS) setup at the University of Vienna, which has excellent isobaric separation performance. The isobaric interference of $$^{90}$$Zr in the $$^{90}$$Sr AMS was first removed by chemical separation. The separation factor of Zr in two-step column chromatography with Sr resin and anion exchange resin was 10$$^{6}$$. The $$^{90}$$Zr remaining in the sample was removed by ILIAMS effectively. This simple chemical separation achieved a limit of detection $$<$$ 0.1 mBq in the $$^{90}$$Sr AMS, which is lower than typical $$beta$$-ray detection. The agreement between AMS measurements and nominal values for the $$^{90}$$Sr concentrations of IAEA samples indicated that the new highly-sensitive $$^{90}$$Sr analysis in the environmental samples with AMS is reliable even for high matrix samples of soil and bone.

Journal Articles

${it Neocalanus cristatus}$ (Copepoda) from a deep sediment-trap; Abundance and implications for ecological and biogeochemical studies

Ikenoue, Takahito*; Otosaka, Shigeyoshi*; Honda, Makio*; Kitamura, Minoru*; Mino, Yoshihisa*; Narita, Hisashi*; Kobayashi, Takuya

Frontiers in Marine Science (Internet), 9, p.884320_1 - 884320_11, 2022/05

 Times Cited Count:0 Percentile:0.01

We studied seasonal variations of the mesozooplankton swimmer community collected by a sediment trap moored at 873 m in the Kuroshio & Oyashio Transition region off the east coast of Japan from 5 August 2011 to 23 June 2013. The total flux of mesozooplankton swimmers varied between 0 and 11.1 individuals m-2 d-1, with a mean of 3.1 individuals m-2 d-1 during the sampling period. Among the Copepoda, Neocalanus cristatus was the most dominant taxon. The species composition of the swimmers closely reflected the mid-depth mesozooplankton of the Oyashio region. The fluxes of Neocalanus species reflected ontogenetic vertical migration, but may have been overestimates of active fluxes if they included dormant individuals that accidentally entered the sediment trap.

Journal Articles

Developing accelerator mass spectrometry capabilities for anthropogenic radionuclide analysis to extend the set of oceanographic tracers

Hain, K.*; Martschini, M.*; G$"u$lce, F.*; Honda, Maki; Lachner, J.*; Kern, M.*; Pitters, J.*; Quinto, F.*; Sakaguchi, Aya*; Steier, P.*; et al.

Frontiers in Marine Science (Internet), 9, p.837515_1 - 837515_17, 2022/03

 Times Cited Count:9 Percentile:97.62(Environmental Sciences)

Recent major advances in accelerator mass spectrometry (AMS) at the Vienna Environmental Research Accelerator (VERA) regarding detection efficiency and isobar suppression have opened possibilities for the analysis of additional long-lived radionuclides at ultra-low environmental concentrations. These radionuclides, including $$^{233}$$U, $$^{135}$$Cs, $$^{99}$$Tc and $$^{90}$$Sr, will become important for oceanographic tracer application due to their generally conservative behavior in ocean water. In particular, the isotope ratios $$^{233}$$U/$$^{236}$$U and $$^{137}$$Cs/$$^{135}$$Cs have proven to be powerful fingerprints for emission source identification as they are not affected by elemental fractionation. Improved detection efficiencies allowed us to analyze all major long-lived actinides, i.e. $$^{236}$$U, $$^{237}$$Np, $$^{239, 240}$$Pu, $$^{241}$$Am as well as the very rare $$^{233}$$U, in the same 10 L water samples of an exemplary depth profile from the northwest Pacific Ocean. Especially for $$^{90}$$Sr analysis, our new approach has already been validated for selected reference materials (e.g. IAEA-A-12) and is ready for application in oceanographic studies. We estimate that a sample volume of only (1-3) L ocean water is sufficient for $$^{90}$$Sr as well as $$^{135}$$Cs analysis, respectively.

Journal Articles

A Compilation of the 10-year studies on $$^{129}$$I in the terrestrial environment after the Fukushima Dai-ichi Nuclear Power Plant accident

Honda, Maki

Chikyu Kagaku, 55(4), p.176 - 192, 2021/12

Iodine 129 ($$^{129}$$I) is a radionuclide that decays to $$^{129}$$Xe with a half-life of 15.7 million years. The analysis of $$^{129}$$I in the environment has played an important role not only in the fields of planetary science and earth science, but also in the nuclear field in recent years. Particularly, in the case of the Fukushima Dai-ichi Nuclear Power Plant accident in March, 2011, the scientists estimated the distribution and soil deposition of $$^{131}$$I over a wide area, and contributed to the assessment of internal exposure doses in the early stage of the accident. This is one of the most significant achievements in recent $$^{129}$$I-related studies. Future studies are expected to be conducted to elucidate the transport mechanism of $$^{129}$$I from land to river and sea, and to investigate the possible accumulation of $$^{129}$$I in aquatic organisms. The mobility of $$^{129}$$I in the soil studied by the author during the 10-years since the accident has been mainly reviewed in this manuscript.

Journal Articles

$$^{60}$$Fe and $$^{244}$$Pu deposited on Earth constrain the r-process yields of recent nearby supernovae

Wallner, A.*; Froehlich, M. B.*; Hotchkis, M. A. C.*; Kinoshita, N.*; Paul, M.*; Martschini, M.*; Pavetich, S.*; Tims, S. G.*; Kivel, N.*; Schumann, D.*; et al.

Science, 372(6543), p.742 - 745, 2021/05

 Times Cited Count:31 Percentile:96.65(Multidisciplinary Sciences)

Half of the chemical elements heavier than iron are produced by the rapid neutron capture process (r-process). The sites and yields of this process are disputed, with candidates including some types of supernovae (SNe) and mergers of neutron stars. We search for two isotopic signatures in a sample of Pacific Ocean crust-iron-60 ($$^{60}$$Fe) (half-life, 2.6 million years), which is predominantly produced in massive stars and ejected in supernova explosions, and $$^{244}$$Pu (half-life, 80.6 million years), which is produced solely in r-process events. We detect two distinct influxes of $$^{60}$$Fe to Earth in the last 10 million years and accompanying lower quantities of $$^{244}$$Pu. The $$^{244}$$Pu/$$^{60}$$Fe influx ratios are similar for both events. The $$^{244}$$Pu influx is lower than expected if SNe dominate r-process nucleosynthesis, which implies some contribution from other sources.

Journal Articles

Thermally altered subsurface material of asteroid (162173) Ryugu

Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Takagi, Yasuhiko*; Nakamura, Tomoki*; Hiroi, Takahiro*; Matsuoka, Moe*; et al.

Nature Astronomy (Internet), 5(3), p.246 - 250, 2021/03

 Times Cited Count:30 Percentile:96.42(Astronomy & Astrophysics)

Here we report observations of Ryugu's subsurface material by the Near-Infrared Spectrometer (NIRS3) on the Hayabusa2 spacecraft. Reflectance spectra of excavated material exhibit a hydroxyl (OH) absorption feature that is slightly stronger and peak-shifted compared with that observed for the surface, indicating that space weathering and/or radiative heating have caused subtle spectral changes in the uppermost surface. However, the strength and shape of the OH feature still suggests that the subsurface material experienced heating above 300 $$^{circ}$$C, similar to the surface. In contrast, thermophysical modeling indicates that radiative heating does not increase the temperature above 200 $$^{circ}$$C at the estimated excavation depth of 1 m, even if the semimajor axis is reduced to 0.344 au. This supports the hypothesis that primary thermal alteration occurred due to radiogenic and/or impact heating on Ryugu's parent body.

Journal Articles

A Sensitive method for Sr-90 analysis by accelerator mass spectrometry

Sasa, Kimikazu*; Honda, Maki; Hosoya, Seiji*; Takahashi, Tsutomu*; Takano, Kenta*; Ochiai, Yuta*; Sakaguchi, Aya*; Kurita, Saori*; Satou, Yukihiko; Sueki, Keisuke*

Journal of Nuclear Science and Technology, 58(1), p.72 - 79, 2021/01

 Times Cited Count:8 Percentile:74.98(Nuclear Science & Technology)

Journal Articles

The Surface composition of asteroid 162173 Ryugu from Hayabusa2 near-infrared spectroscopy

Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Arai, Takehiko*; Nakauchi, Yusuke*; Nakamura, Tomoki*; Matsuoka, Moe*; et al.

Science, 364(6437), p.272 - 275, 2019/04

 Times Cited Count:233 Percentile:99.75(Multidisciplinary Sciences)

The near-Earth asteroid 162173 Ryugu, the target of Hayabusa2 sample return mission, is believed to be a primitive carbonaceous object. The Near Infrared Spectrometer (NIRS3) on Hayabusa2 acquired reflectance spectra of Ryugu's surface to provide direct measurements of the surface composition and geological context for the returned samples. A weak, narrow absorption feature centered at 2.72 micron was detected across the entire observed surface, indicating that hydroxyl (OH)-bearing minerals are ubiquitous there. The intensity of the OH feature and low albedo are similar to thermally- and/or shock-metamorphosed carbonaceous chondrite meteorites. There are few variations in the OH-band position, consistent with Ryugu being a compositionally homogeneous rubble-pile object generated from impact fragments of an undifferentiated aqueously altered parent body.

Journal Articles

Depth profile and inventory of $$^{36}$$Cl in soil near the Fukushima Dai-ichi Nuclear Power Plant

Ota, Yuki*; Sueki, Keisuke*; Sasa, Kimikazu*; Takahashi, Tsutomu*; Matsunaka, Tetsuya*; Matsumura, Masumi*; Tosaki, Yuki*; Honda, Maki*; Hosoya, Seiji*; Takano, Kenta*; et al.

JAEA-Conf 2018-002, p.99 - 102, 2019/02

no abstracts in English

Journal Articles

NIRS3; The Near Infrared Spectrometer on Hayabusa2

Iwata, Takahiro*; Kitazato, Kohei*; Abe, Masanao*; Otake, Makiko*; Arai, Takehiko*; Arai, Tomoko*; Hirata, Naru*; Hiroi, Takahiro*; Honda, Chikatoshi*; Imae, Naoya*; et al.

Space Science Reviews, 208(1-4), p.317 - 337, 2017/07

 Times Cited Count:49 Percentile:71.4(Astronomy & Astrophysics)

NIRS3: The Near Infrared Spectrometer is installed on the Hayabusa2 spacecraft to observe the target C-type asteroid 162173 Ryugu at near infrared wavelengths of 1.8 to 3.2 micrometer. It aims to obtain reflectance spectra in order to detect absorption bands of hydrated and hydroxide minerals in the 3 micrometer-band. We adopted a linear-image sensor with indium arsenide (InAs) photo diodes and a cooling system with a passive radiator to achieve an optics temperature of 188 K, which enables to retaining sufficient sensitivity and noise level in the 3 micrometer wavelength region. We conducted ground performance tests for the NIRS3 flight model (FM) to confirm its baseline specifications. The results imply that the properties such as the signal-to-noise ratio (SNR) conform to scientific requirements to determine the degree of aqueous alteration, such as CM or CI chondrite, and the stage of thermal metamorphism on the asteroid surface.

Journal Articles

Resuspension and lateral transport of seafloor sediment contaminated with artificial radionuclides derived from Fukushima Daiichi Nuclear Power Plant accident

Honda, Makio*; Otosaka, Shigeyoshi

Nihon Genshiryoku Gakkai-Shi ATOMO$$Sigma$$, 58(4), p.225 - 228, 2016/04

Transport processes of particulate radiocesium obtained from a three year time-series sediment trap experiments at a site 115 km southeast of Fukushima Daiichi Nuclear Power Plant off Fukushima are expounded. Results show a high fraction of lithogenic material in sinking particles, suggesting a lateral source of sediments. In particular, we found that accident-derived radiocesium associate with slope and shelf sediments were resuspended and transported laterally to the offshore regions in typhoon seasons in 2013. Continuous observation of such transport processes of particulate radiocesium near the seabed would be significant for better understanding of the fate of accident-derived radiocesium.

Journal Articles

Tracking the fate of particle associated Fukushima Daiichi cesium in the ocean off Japan

Buesseler, K. O.*; German, C. R.*; Honda, Makio*; Otosaka, Shigeyoshi; Black, E. E.*; Kawakami, Hajime*; Manganini, S. M.*; Pike, S.*

Environmental Science & Technology, 49(16), p.9807 - 9816, 2015/08

 Times Cited Count:22 Percentile:57.13(Engineering, Environmental)

A three year time-series of particle fluxes is presented from sediment traps deployed at 500 and 1000 m at a site 115 km southeast of Fukushima Daiichi Nuclear Power Plant (FDNPP). Results show a high fraction of lithogenic material, suggesting a lateral source of sediments. The accident-derived radiocesium were enhanced in flux peaks that, given variations in trap $$^{137}$$Cs/$$^{210}$$Pb ratios, are characteristic of material derived from shelf and slope sediments found from $$<$$ 120 to $$>$$ 500 m. The fluxes of radiocesium are an order of magnitude higher than a previously reported for the trap located 100 km due east of FDNPP. We attribute the large difference due to the position of our trap under the southeasterly currents that carry contaminated waters and resuspended sediments in to the Pacific. These higher sedimentary fluxes of radiocesium to the offshore are still small relative to the inventory of radiocesium currently buried nearshore.

Journal Articles

X-ray absorption spectroscopy and novel electronic properties in heavy fermion compounds YbT$$_{2}$$Zn$$_{20}$$ (T: Rh and Ir)

Honda, Fuminori*; Hirose, Yusuke*; Miyake, Atsushi*; Mizumaki, Masaichiro*; Kawamura, Naomi*; Tsutsui, Satoshi*; Watanuki, Tetsu; Watanabe, Shinji*; Takeuchi, Tetsuya*; Settai, Rikio*; et al.

Journal of Physics; Conference Series, 592(1), p.012021_1 - 012021_5, 2015/03

 Times Cited Count:2 Percentile:61.25

no abstracts in English

Journal Articles

Analysis of translocation and distribution of photoassimilates in eggplant fruit in relation to positions of the source leaves using the positron-emitting tracer imaging system

Kikuchi, Kaori*; Kawachi, Naoki; Ishii, Satomi; Suzui, Nobuo; Ito, Sayuri; Ishioka, Noriko; Honda, Ichiro*; Fujimaki, Shu

JAEA-Review 2009-041, JAEA Takasaki Annual Report 2008, P. 105, 2009/12

Journal Articles

Modeling of chemical transition of nitrate accompanied with corrosion of carbon steel under alkaline conditions

Honda, Akira; Masuda, Kaoru*; Imakita, Tsuyoshi*; Kato, Osamu*; Nishimura, Tsutomu*

Zairyo To Kankyo, 58(5), p.182 - 189, 2009/05

Interaction between carbon steel and nitrate was modeled using the mixed potential concept. Carbon steel was selected as an example of metal components in the repository of radioactive waste. The nitrate reduction accompanied by the corrosion of carbon steel was modeled as a reaction series such as nitrate - nitrite - ammonia. The sum of the current of the reaction series of nitrate - nitrite - ammonia and that of water reduction was assumed to balance with the corrosion current of carbon steel. The input parameters for this kinetic model were determined by electrochemical measurement and immersion test. The results of the immersion test can be interpreted by the analyses of the model.

Journal Articles

Visualization of photoassimilate translocation in eggplant fruit using $$^{11}$$CO$$_{2}$$ and a positron-emitting tracer imaging system

Kikuchi, Kaori*; Ishii, Satomi; Fujimaki, Shu; Suzui, Nobuo; Matsuhashi, Shimpei; Honda, Ichiro*; Kawachi, Naoki

JAEA-Review 2008-055, JAEA Takasaki Annual Report 2007, P. 110, 2008/11

Journal Articles

Real-time analysis of photoassimilate translocation in intact eggplant fruit using $$^{11}$$CO$$_{2}$$ and a positron-emitting tracer imaging system

Kikuchi, Kaori*; Ishii, Satomi; Fujimaki, Shu; Suzui, Nobuo; Matsuhashi, Shimpei; Honda, Ichiro*; Shishido, Yoshihiro*; Kawachi, Naoki

Journal of the Japanese Society for Horticultural Science, 77(2), p.199 - 205, 2008/04

To clarify the mechanism of growth and development of the fruit of eggplant,$$^{11}$$CO$$_{2}$$was fed to a leaf and the translocation of $$^{11}$$C-labeled photoassimilate into the fruit was monitored by PETIS. Continuous images of the translocation of $$^{11}$$C-photoassimilate from the leaf to the fruit were successfully made, with a shorter time resolution than ever reported before. The PETIS images indicated that translocation of photoassimilate within the fruit was not uniform. The velocity of photoassimilate translocation in the peduncle and the changes in the rate of translocation of photoassimilate in the fruit were estimated by analysis of the PETIS data. The advantages of PETIS measurements in physiological studies of source sink relationships are discussed.

Journal Articles

Imaging of translocation and spatial distribution of the assimilated carbon and nitrogen in the host-root parasite system by PETIS

Sekimoto, Hitoshi*; Kawachi, Naoki; Honda, Shuzo*; Yamaguchi, Yoshie*; Kato, Shota*; Yoneyama, Kaori*; Fujimaki, Shu; Suzui, Nobuo; Ishii, Satomi; Watanabe, Satoshi; et al.

JAEA-Review 2007-060, JAEA Takasaki Annual Report 2006, P. 124, 2008/03

no abstracts in English

42 (Records 1-20 displayed on this page)