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MethanoperedenaceaeNishimura, Hiroki*; Kozuka, Mariko*; Fukuda, Akari*; Ishimura, Toyoho*; Amano, Yuki; Beppu, Hikari*; Miyakawa, Kazuya; Suzuki, Yohei*
Environmental Microbiology Reports (Internet), 15(3), p.197 - 205, 2023/06
Times Cited Count：1 Percentile：48.3(Environmental Sciences)The family Methanoperedenaceae archaea mediate anaerobic oxidation of methane (AOM). We newly developed a high-pressure laboratory incubation system and investigated groundwater from 214- and 249-m deep boreholes at Horonobe Underground Research Laboratory, Japan, where the high and low abundances of Methanoperedenaceae archaea have been revealed, respectively. We incubated the samples amended with or without amorphous Fe(III) and 
C-labelled methane at an in-situ pressure of 1.6 MPa. After three to seven-day incubation, AOM activities were not detected from the 249-m sample but from the 214-m sample. The AOM rates were 93.7
40.6 and 27.737.5 nM/day with and without Fe(III) amendment. Suspended particulates were not visible in the 249-m sample on the filter, while they were abundant and contained amorphous Fe(III) and Fe(III)-bearing phyllosilicates in the 214-m sample. This supports the in-situ activity of Fe(III)-dependent AOM in the deep subsurface borehole.
Hain, K.*; Martschini, M.*; G
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：12 Percentile：95.78(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 
U, 
Cs, 
Tc and 
Sr, will become important for oceanographic tracer application due to their generally conservative behavior in ocean water. In particular, the isotope ratios U/
U and 
Cs/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. U, 
Np, 
Pu, 
Am as well as the very rare U, in the same 10 L water samples of an exemplary depth profile from the northwest Pacific Ocean. Especially for 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 Sr as well as Cs analysis, respectively.
Kawamura, Hideyuki; Hirose, Naoki*; Nakayama, Tomoharu*; Ito, Toshimichi
JAEA-Data/Code 2021-004, 34 Pages, 2021/05
JAEA-Data-Code-2021-004.pdf:3.72MB
The Japan Atomic Energy Agency measured the ocean current across the Tsugaru Strait using an Acoustic Doppler Current Profiler attached on a ferryboat from October 1999 to January 2008. The characteristics of the ocean current in the Tsugaru Strait must be understood for predicting oceanic dispersion of radioactive materials released from nuclear facilities around the strait. Furthermore, it is critical to elucidate the mechanism of the Tsugaru Warm Current from an oceanography viewpoint. The dataset obtained in this investigation consists of daily ocean current data files that record the components of the current speed in the east-west and north-south directions from the surface layer to the bottom layer. The dataset stores 2,211 daily ocean current data files, despite some data periods missing from October 1999 to January 2008. In this study, information on the dataset is described for users to analyze the dataset properly for their purposes. Section 1 provides the background and purpose of the ocean current measurement, Section 2 explains the methodology of measurement using an Acoustic Doppler Current Profiler, and Section 3 explains the record format of the daily ocean current data files and data acquisition rate and presents analysis results. Finally, Section 4 concludes this study.
Kobayashi, Takuya; Kawamura, Hideyuki; Kamidaira, Yuki
Nihon Genshiryoku Gakkai-Shi ATOMO
, 62(11), p.635 - 639, 2020/11
It is important to predict the dispersion of radioactive materials released into the ocean due to nuclear accidents in the surrounding ocean of the east Asian countries. The Japan Atomic Energy Agency developed a Short-Term Emergency Assessment system of Marine Environmental Radioactivity (STEAMER) based on an oceanic dispersion model. STEAMER quickly predicts the oceanic dispersion of radioactive materials in the surrounding ocean of the east Asian countries using the online prediction data of oceanic condition. We validated the predictability of the oceanic dispersion and demonstrated the improvement of the predictability using an ensemble prediction method. Moreover, we developed a high resolution model in the coastal region using a Regional Ocean Modeling System (ROMS).
Miwa, Kazuji; Obata, Hajime*; Suzuki, Takashi
Journal of Nuclear Science and Technology, 57(5), p.537 - 545, 2020/05
Times Cited Count：2 Percentile：20.94(Nuclear Science & Technology)This study investigated the vertical distribution of Iodine-129 (
I) which is mainly produced by European nuclear reprocessing plants in the Chukchi Sea and Bering Sea. I was found to be distributed almost uniformly in fallout level, and an increasing in I concentration levels caused by high I water inflow from the Atlantic Ocean was not observed. Additionally, we revealed the vertical distribution of iodide, one chemical form of iodine, from the Bering Shelf area to the Chukchi Sea for the first time. The increasing tendency of iodide near sea bottom was observed.
Kawamura, Hideyuki; Kamidaira, Yuki; Kobayashi, Takuya
Journal of Nuclear Science and Technology, 57(4), p.472 - 485, 2020/04
Times Cited Count：3 Percentile：30.79(Nuclear Science & Technology)The Japan Atomic Energy Agency developed a Short-Term Emergency Assessment system of the Marine Environmental Radioactivity (STEAMER) to predict the oceanic dispersion of radionuclides in the ocean around Japan. The purpose of this study is to validate the predictability of STEAMER using oceanographic forecast and reanalysis data, which were saved for past several years. Results of oceanic dispersion simulations that are driven by oceanographic reanalysis data are assumed to be true solutions. Oceanic dispersion simulations are conducted for Cs-137 released hypothetically from the Fukushima Daiichi Nuclear Power Plant. The predictability of STEAMER is quantitatively examined for the length of the forecast period. Ensemble forecast simulations are also conducted to successfully improve the predictability of STEAMER.
Miwa, Kazuji; Takeda, Seiji; Iimoto, Takeshi*
Radiation Protection Dosimetry, 184(3-4), p.372 - 375, 2019/10
Times Cited Count：0 Percentile：0.01(Environmental Sciences)The Ministry of the Environment has indicated the policy of recycling the contaminated soil generated by decontamination activity after the Fukushima accident. By recycling to coastal reclamation which is one of effective recycling application, dissolved radiocesium and absorbed radiocesium on soil particles will flow out to the ocean by construction, therefore evaluating radiocesium transition in ocean considering the both types of radiocesium is important for safety assessment. In this study, the radiocesium outflow during constructing and after constructing is modeled, and radiocesium transition in ocean is evaluated by Sediment model suggested in OECD/NEA. The adaptability of sediment model is confirmed by reproducing evaluation of the coastal area of Fukushima. We incorporate the sediment model to PASCLR2 code system to evaluate the doses from radiocesium in ocean.
Chino, Masamichi*; Nagai, Haruyasu
Environmental Contamination from the Fukushima Nuclear Disaster; Dispersion, Monitoring, Mitigation and Lessons Learned, p.50 - 61, 2019/00
Times Cited Count：8 Percentile：82.45(Environmental Sciences)Temporal variations in the amount of radionuclides released into the atmosphere during the Fukushima Daiichi Nuclear Power Station accident and their atmospheric dispersion are essential to evaluate the environmental impacts and resultant radiological doses to the public. We have estimated the atmospheric releases during the accident by comparing measurements with calculations by atmospheric deposition model. UNSCEAR compared several estimated source terms and used our source term for estimating levels of radioactive material in the terrestrial environment and doses to the public. To improve our source term, we recently made detailed source term estimation by using additional monitoring data and WSPEEDI including new deposition scheme.
Aoyama, Michio*; Yamazawa, Hiromi*; Nagai, Haruyasu
Nihon Genshiryoku Gakkai-Shi ATOMO, 60(1), p.46 - 50, 2018/01
no abstracts in English
Kawamura, Hideyuki; Furuno, Akiko; Kobayashi, Takuya; In, Teiji*; Nakayama, Tomoharu*; Ishikawa, Yoichi*; Miyazawa, Yasumasa*; Usui, Norihisa*
Journal of Environmental Radioactivity, 180, p.36 - 58, 2017/12
Times Cited Count：11 Percentile：34.92(Environmental Sciences)This study simulates the oceanic dispersion of Fukushima-derived Cs-137 by an oceanic dispersion model and multiple oceanic general circulation models. The models relatively well reproduced the observed Cs-137 concentrations in the coastal, offshore, and open oceans. Multiple simulations in the coastal, offshore, and open oceans consistently suggested that Cs-137 dispersed along the coast in the north-south direction during the first few months post-disaster, and were subsequently dispersed offshore by the Kuroshio Current and Kuroshio Extension. Quantification of the Cs-137 amounts suggested that Cs-137 actively dispersed from the coastal and offshore oceans to the open ocean, and from the surface layer to the deeper layers in the North Pacific.
Kobayashi, Takuya; Kawamura, Hideyuki; Fujii, Katsuji*; Kamidaira, Yuki
Journal of Nuclear Science and Technology, 54(5), p.609 - 616, 2017/05
Times Cited Count：10 Percentile：68.29(Nuclear Science & Technology)The Japan Atomic Energy Agency has, for many years, been developing a radionuclide dispersion model for the ocean, and has validated the model through application in many sea areas using oceanic flow fields calculated by the ocean model. The Fukushima Dai-ichi Nuclear Power Station accident caused marine pollution by artificial radioactive materials to the North Pacific, especially to coastal waters northeast of mainland Japan. In order to investigate the migration of radionuclides in the ocean caused by this severe accident, studies using marine dispersion simulations have been carried out by JAEA. Based on these as well as the previous studies, JAEA has developed the Short-Term Emergency Assessment system of Marine Environmental Radioactivity (STEAMER) to immediately predict the radionuclide concentration around Japan in case of a nuclear accident.
; Soft X-ray absorption, magnetic circular dichroism, and angle-resolved photoemission spectroscopiesSaito, Yuji; Fujiwara, Hidenori*; Yamaguchi, Takashi*; Nakatani, Yasuhiro*; Mori, Takeo*; Fuchimoto, Hiroto*; Kiss, Takayuki*; Yasui, Akira*; Miyawaki, Jun*; Imada, Shin*; et al.
Journal of the Physical Society of Japan, 85(11), p.114713_1 - 114713_7, 2016/11
Times Cited Count：15 Percentile：67.68(Physics, Multidisciplinary)We report on the electronic structures of ferromagnetic CeAgSb using soft X-ray absorption (XAS), magnetic circular dichroism (XMCD), and angle-resolved photoemission (ARPES) spectroscopies. The Ce 
XAS spectra show very small satellite structures, reflecting a strongly localized character of the Ce 4
electrons. The linear dichroism effects in the Ce XAS spectra demonstrate the ground-state Ce 4 symmetry of 
, the spatial distribution of which is directed along the 
-axis. Nevertheless, ARPES spectra at the Ce 3
-4
resonance show the momentum dependence of the intensity ratio between Ce 4
and 4
peaks in a part of the Brillouin zone, suggesting the non negligible momentum-dependent hybridization effect between the Ce 4 and the conduction electrons. This is associated with the moderate mass enhancement in CeAgSb.
Kobayashi, Takuya; In, Teiji*; Ishikawa, Yoichi*
Journal of Nuclear Science and Technology, 52(6), p.769 - 772, 2015/06
Times Cited Count：1 Percentile：9.61(Nuclear Science & Technology)Ocean diffusion concentration maps were developed to gain an understanding of the migration behavior of contaminated water leaking from the Fukushima Dai-ichi Nuclear Power Plant. We used ensemble mean values to define the semi-climatological seasonal field in our calculations of the trajectories of the contaminated water. The maps were validated by conducting actual release events in two different seasons. The results showed that despite their simplicity, the proposed methods yield relatively good results.
Kato, Aitaro*; Saiga, Atsushi; Takeda, Tetsuya*; Iwasaki, Takaya*; Matsuzawa, Toru*
Earth, Planets and Space (Internet), 66(1), p.86_1 - 86_8, 2014/12
Times Cited Count：22 Percentile：55.14(Geosciences, Multidisciplinary)To understand the mechanism of an intensive non-volcanic seismic swarm in the Kii Peninsula, Japan, we used a dense seismic linear array to measure fine-scale variations of seismic velocities and converted teleseismic waves. A low-velocity anomaly confined to just beneath the seismic swarm area is clearly imaged, which spatially correlates with an uplifted surface area, and a highly conductive and strong attenuative body. These results suggest that fluids such as partial melt or water are present beneath this non-volcanic seismic swarm area. It is notable that the island arc Moho below the seismic swarm area is at depths of ca. 32 km in the northern part of the seismic swarm area, and shallows to ca. 20 km towards the south, due to an upwardly raised structure of serpentinized mantle wedge. In addition, we show that hydrated oceanic crust of the subducting Philippine Sea slab is characterized by low-velocities with a high Poisson's ratio at depths shallower than 40 km. Water released from the subducting oceanic crust could cause serpentinization of the mantle wedge and infiltration into the forearc base of the overlying plate. The interaction between dehydration of the subducting oceanic crust and hydration of the mantle wedge and overlying plate exerts an important role in driving the non-volcanic seismic swarm activity in the Kii Peninsula.
Nagai, Haruyasu; Kurihara, Osamu*
Nihon Genshiryoku Gakkai-Shi ATOMO, 56(12), p.791 - 795, 2014/12
no abstracts in English
Kobayashi, Takuya; Chino, Masamichi; Togawa, Orihiko
Journal of Nuclear Science and Technology, 43(5), p.569 - 575, 2006/05
Times Cited Count：3 Percentile：24.07(Nuclear Science & Technology)A dissolved radionuclide migration code system that consists of a ocean circulation model, Princeton Ocean Model, and a particle random-walk model, SEA-GEARN, has been developed. The oceanic migration of Cs discharged from a nuclear submarine in a hypothetical accident at the Tsushima Strait was calculated in the southwestern area of the Japan Sea as a model application. The calculations for instantaneous releases every 10 days were carried out for one year to study the seasonal differences of migration process of the dissolved radionuclides. The migration tendencies of dissolved radionuclides were divided into two patterns. For the releases started from January to September, all of the high concentration areas migrated to the northeast along the coastline of the Main Island of Japan from the release point. As for the releases from October to December, some high concentrations areas migrated to the west from the release point and the concentrations of Cs along the coastline of the Main Island of Japan were comparatively low.
Tanimura, Yoshihiko; Yoshizawa, Michio; Saegusa, Jun; Fujii, Katsutoshi; Shimizu, Shigeru; Yoshida, Makoto; Shibata, Yasunari*; Uritani, Akira*; Kudo, Katsuhisa*
Radiation Protection Dosimetry, 110(1-4), p.85 - 89, 2004/09
Times Cited Count：19 Percentile：75.11(Environmental Sciences)Mono-energetic neutron calibration fields have been developed at the Facility of Radiation Standards (FRS) of JAERI using 4MV Van-de-Graaff (Pelletron) accelerator. The fields of 144 keV, 565 keV and 5.0 MeV neutrons were constructed with estimating neutron energy spectra and establishing the traceability of reference neutron fluence.
Povinec, P. P.*; Aramaki, Takafumi*; Burr, G. S.*; Jull, A. J. T.*; Liong Wee Kwong, L.*; Togawa, Orihiko
Radiocarbon, 46(2), p.583 - 594, 2004/09
Times Cited Count：16 Percentile：32.42(Geochemistry & Geophysics)no abstracts in English
FeCoO
and SrBaFeCoO; Effects induced by magnetic order and transport coherenceRykov, A. I.*; Nomura, Kiyoshi*; Sawada, Tsuguo*; Mitsui, Takaya; Seto, Makoto*; Tamegai, Tsuyoshi*; Tokunaga, Masashi*
Physical Review B, 68(22), p.224401_1 - 224401_7, 2003/12
Times Cited Count：8 Percentile：42.83(Materials Science, Multidisciplinary)no abstracts in English
Seko, Noriaki; Katakai, Akio; Hasegawa, Shin; Tamada, Masao; Kasai, Noboru; Takeda, Hayato*; Sugo, Takanobu; Saito, Kyoichi*
Nuclear Technology, 144(2), p.274 - 278, 2003/11
Times Cited Count：129 Percentile：98.76(Nuclear Science & Technology)The total amount of uranium dissolved in seawater at a uniform concentration of 3 mg-U/m
in the world's oceans is 4.5 billion tons. An adsorption method using polymeric adsorbents capable of specifically recovering uranium from seawater is reported to be economically feasible. A uranium-specific non-woven fabric was used as the adsorbent packed in an adsorption cage. We submerged adsorption cages, 16 m
in cross-sectional area and 16 cm in height, in the Pacific Ocean at a depth of 20 m at 7 km offshore of Japan. The cage consisted of stacks of 52,000 sheets of the uranium-specific non-woven fabric with a total mass of 350 kg. The total amount of uranium recovered by the non-woven fabric was more than one kg in terms of yellow cake during a total submersion time of 240 days in the ocean.
