Researcher basic information

• Ph.D., Tohoku University. Japan, Jun. 2013

• https://researchmap.jp/ohtomonaga?lang=en

• 80612902

• 201301058051492411

• Serpentinization
• Chromian spinel
• Acid mine drainage
• Early Earth
• Archaean
• Iron Formation
• Origin of life

• Natural Science, Biogeosciences
• Natural Science, Solid earth sciences
• Life Science, Ecology and environment

• Bachelor's degree program, School of Engineering
• Master's degree program, Graduate School of Engineering
• Doctoral (PhD) degree program, Graduate School of Engineering

Research activity information

• May 2016, 一般財団法人山下太郎顕彰育英会, 第27回山下太郎学術研究奨励賞
  約38億年前初期太古代岩石中に残された最古の生命の痕跡の発見
  大友陽子

• Enhanced rock weathering in acid mine drainage systems: Field evidence and passive treatment implications
  Htut San Hkaung; Naito Yamashita; Nono Kimotsuki; Fugo Nakamura; Frances Chikanda; Ryosuke Kikuchi; Yoko Ohtomo; Tsubasa Otake; Tsutomu Sato
  Cleaner Engineering and Technology, 32, 101203, 101203, Elsevier BV, Jun. 2026, [Peer-reviewed]
  English, Scientific journal
• Exploring hyperspectral imaging and regression-based analysis as an alternative to MLA for mineral composition
  Nozaki, H.; Okada, N.; Takizawa, K.; Andre Manjate, E. P.; Ohtomo, Y.; Kawamura, Y.
  International Journal of Mining, Reclamation and Environment, 1, 23, Mar. 2026, [Peer-reviewed]
  English, Scientific journal
• Abiotic, Catalytic Dominance in Manganese Removal From Acid Mine Drainage: Role and Mechanism of Birnessite Formed on Sand Filters
  Joseph Godirilwe; Kenta Hasegawa; Frances Chikanda; Yoko Ohtomo; Shingo Tomiyama; Ryosuke Kikuchi; Shigeshi Fuchida; Tsutomu Sato; Tsubasa Otake
  Resource Geology, 76, 1, Wiley, Jan. 2026, [Peer-reviewed]
  English, Scientific journal, ABSTRACT
  
  Efficient manganese (Mn) removal from acidic mine drainage (AMD) is challenging due to its high solubility and slow oxidation kinetics. We investigate a mechanism that enables the efficient removal of Mn in a sand filter at an operational AMD treatment facility, with particular emphasis on naturally formed Mn oxides on sand grain surfaces (Mn‐precipitated sand; MPS). Characterization of the filter media using x‐ray fluorescence, x‐ray diffraction, scanning electron microscopy, and transmission electron microscopy identified a coating of poorly crystalline birnessite (δ‐MnO ₂ ) that formed in situ on the MPS and is absent on unprecipitated sand (UNS). X‐ray absorption near‐edge structure spectroscopy confirmed that this coating is composed mainly of tetravalent Mn(IV). Batch experiments simulating filtration conditions were performed to compare Mn removal kinetics using MPS, UNS, and commercial Mn oxide powder from thickener mine water and pure water with 2 mg/L dissolved Mn ²⁺ . The MPS removed > 99% of the dissolved Mn within 3 h from both mine and pure water, whereas UNS only removed some Mn (< 20% after 96 h). Microbial inhibition tests using UV‐irradiated and ampicillin‐treated MPS in pure water confirmed that this rapid Mn removal was dominated by abiotic physicochemical processes. This abiotic, autocatalytic oxidation mechanism proved effective even at a neutral pH, achieving > 96% removal. These findings reveal that Mn removal is driven by abiotic autocatalysis on a naturally formed, Mn(IV)‐rich birnessite coating. The high efficiency of this process at a neutral pH presents a significant opportunity to optimize AMD treatment by lowering operational pH and reducing chemical consumption and sludge production for a more sustainable remediation strategy.
• Monitoring tailings storage facilities with multi-temporal DInSAR: A systematic review
  Vanessa Sánchez; Francisco Cabrera-Torres; Susana Arciniegas; Natsuo Okada; Yoko Ohtomo; Fidelis Suorineni; Youhei Kawamura
  Science of The Total Environment, 1011, 181161, 181161, Elsevier BV, Jan. 2026, [Peer-reviewed]
  English, Scientific journal
• Artificial Intelligence-Based Hyperspectral Classification of Rare Earth Element-Related Heavy Mineral Sand
  Okhala Muacanhia; Natsuo Okada; Yoko Ohtomo; Youhei Kawamura
  Minerals, 15, 10, 1015, 1015, MDPI AG, 25 Sep. 2025, [Peer-reviewed]
  English, Scientific journal, Heavy minerals, such as Rutile, Ilmenite and Zircon, and other essential trace elements are important in modern technology development. The integration of hyperspectral imaging and artificial intelligence presents a promising approach for the accurate identification of heavy minerals, especially Rare Earth Element (REE)–bearing phases such as Monazite. This study evaluates three AI classifiers, Support Vector Machine (SVM), Neural Networks (NNs) and Convolutional Neural Networks (CNNs), for their performance in classifying ten different minerals distributed across six grain size groups ranging from 125 μm to over 300 μm. The analysis focuses on how grain size affects spectral reflectance and classification accuracy. Among the tested models, SVM consistently outperformed NN and CNN, achieving the highest precision, recall and spectral similarity, particularly within the 150–300 μm grain size range. CNN showed the lowest performance and frequently misclassified spectrally similar minerals, such as Zircon and Rutile, likely due to its 1D architecture and limited spatial representation. Monazite, notable for its strong Nd3+ absorption features, was accurately identified across applicable grain sizes, highlighting its reliability for REE detection. Spectral Angle Mapper (SAM) analysis confirmed that SVM and NN maintained better spectral similarity than CNN. In general, the results highlight the significant influence of grain size, spectral similarity and dataset size on classification accuracy and the overall effectiveness of AI models in hyperspectral mineral analysis.
• Magnesium silicate hydrate regulates the dissolution of natural ultramafic rocks and associated hydrogen generation at low temperatures
  Yoko Ohtomo; Shunta Higashino; Ryosuke Kikuchi; Tsubasa Otake; Tsutomu Sato
  GEOCHEMICAL JOURNAL, 59, 5, 207, 223, Geochemical Society of Japan, Sep. 2025, [Peer-reviewed], [Lead author]
  English, Scientific journal
• Advancing arsenic contamination detection in boring cores using hyperspectral imaging and convolutional neural networks
  Kaito Takizawa; Natsuo Okada; Narihiro Owada; Angesom Gebretsadik; Kuroki Hirotada; Yoko Ohtomo; Youhei Kawamura
  Green and Smart Mining Engineering, 2, 3, 246, 258, Elsevier BV, Sep. 2025, [Peer-reviewed]
  English, Scientific journal
• Improving Hokkai shrimp tracking accuracy using YOLOv8 with reflection and parallax correction
  Natsuo Okada; Serina Kubo; Yanhui Zhu; Kaito Takizawa; Shion Wakae; Amane Nakamura; Sakura Igawa; Yoko Ohtomo; Kenji Minami; Kazushi Miyashita; Youhei Kawamura
  Scientific Reports, 15, 1, 29482, Springer Science and Business Media LLC, 12 Aug. 2025, [Peer-reviewed]
  English, Scientific journal
• Strata monitoring for stability analysis and disaster prevention in blast hole open stoping for underground copper mine
  Gopinath Samanta; Angesom Gebretsadik; Fisseha Gebreegziabher; Mujigela Maniteja; Natsuo Okada; Yoko Ohtomo
  Safety in Extreme Environments, 7, 3, Springer Science and Business Media LLC, 12 Jul. 2025, [Peer-reviewed]
  English, Scientific journal
• Improvement of generalization performance of diagnostic system for drill bit abnormality in rotary percussion drilling with grad-CAM
  Yuna Nakazawa; Natsuo Okada; Jo Sasaki; Lesego Senjoba; Yoko Ohtomo; Youhei Kawamura
  Discover Applied Sciences, 7, 4, Springer Science and Business Media LLC, 12 Apr. 2025, [Peer-reviewed]
  Scientific journal
• Integrated spectral image registration protocol for enhanced land pollution assessment and management: bridging satellite and drone data for high-resolution mapping
  Natsuo Okada; Hisatoshi Toriya; Angesom Gebretsadik; Takahiko Arima; Yoko Ohtomo; Youhei Kawamura
  Journal of Material Cycles and Waste Management, Springer Science and Business Media LLC, 04 Oct. 2024, [Peer-reviewed]
  Scientific journal
• APiS (AI powered intelligence spectrum analyser): hyperspectral imaging machine learning analyser app for mineral processing
  Natsuo Okada; Narihiro Owada; Kaito Takizawa; Brian Bino Sinaice; Okhala Muacanhia; Angesom Gebretsadik; Shunki Tanaka; Kosei Aikawa; Ilhwan Park; Mayumi Ito; Yoko Ohtomo; Youhei Kawamura
  International Journal of Mining, Reclamation and Environment, 39, 10, 713, 739, Informa UK Limited, 02 Oct. 2024, [Peer-reviewed]
  Scientific journal
• An AI-Based Approach for Developing a Recommendation System for Underground Mining Methods Pre-Selection
  Elsa Pansilvania Andre Manjate; Natsuo Okada; Yoko Ohtomo; Tsuyoshi Adachi; Bernardo Miguel Bene; Takahiko Arima; Youhei Kawamura
  Mining, 4, 4, 747, 765, MDPI AG, 02 Oct. 2024, [Peer-reviewed]
  Scientific journal, Selecting the most appropriate mining method to recover mineral resources is a critical decision-making task in mining project development. This study introduces an artificial intelligence-based mining methods recommendation system (AI-MMRS) for the pre-selection of underground mining methods. The study integrates and evaluates the capability of two approaches for mining methods selection (MMS): the memory-based collaborative filtering (CF) approach aided by the UBC-MMS system to predict the top-3 relevant mining methods and supervised machine learning (ML) classification algorithms to enhance the effectiveness and novelty of the AI-MMRS, addressing the limitations of the CF approach. The results reveal that the memory-based CF approach achieves an accuracy ranging from 81.8% to 87.9%. Among the classification algorithms, artificial neural network (ANN) and k-nearest neighbors (KNN) classifiers perform the best, with accuracy levels of 66.7% and 63.6%, respectively. These findings demonstrate the effectiveness and viability of both approaches in MMS, acknowledging their limitations and the need for continuous training and optimization. The proposed AI-MMRS for the pre-selection stage supplemented by the direct involvement of mining professionals in later stages of MMS, has the potential to significantly aid in the MMS decision-making, providing data-driven and experience-based recommendations following the ongoing evolution of mining practices.
• Primary Fe isotope signatures record oxidative precipitation in 3.2 Ga ferruginous siliciclastic sedimentary rocks deposited in a shallow ocean environment
  Ryohei Suzumeji; Tsubasa Otake; Daizo Yamauchi; Yoko Ohtomo; Takeshi Kakegawa; Christoph Heubeck; Shin-ichi Yamasaki; Tsutomu Sato
  Precambrian Research, 413, 107574, 107574, Elsevier BV, Oct. 2024, [Peer-reviewed]
  Scientific journal
• Advanced mineralogical classification and concentration estimation in mining with MATLAB-powered hyper-spectral imaging and machine learning
  Natsuo Okada; Brian Bino Sinaice; Jaewon Kim; Hiromasa Nozaki; Kaito Takizawa; Narihiro Owada; Yoko Ohtomo; Youhei Kawamura
  International Journal of Mining, Reclamation and Environment, 1, 21, Informa UK Limited, 06 Jun. 2024, [Peer-reviewed]
  Scientific journal
• Optimizing multi-spectral ore sorting incorporating wavelength selection utilizing neighborhood component analysis for effective arsenic mineral detection
  Natsuo Okada; Hiromasa Nozaki; Shinichiro Nakamura; Elsa Pansilvania Andre Manjate; Angesom Gebretsadik; Yoko Ohtomo; Takahiko Arima; Youhei Kawamura
  Scientific Reports, 14, 1, Springer Science and Business Media LLC, 21 May 2024, [Peer-reviewed]
  Scientific journal, Abstract
  
  Arsenic contamination not only complicates mineral processing but also poses environmental and health risks. To address these challenges, this research investigates the feasibility of utilizing Hyperspectral imaging combined with machine learning techniques for the identification of arsenic-containing minerals in copper ore samples, with a focus on practical application in sorting and processing operations. Through experimentation with various copper sulfide ores, Neighborhood Component Analysis (NCA) was employed to select essential wavelength bands from Hyperspectral data, subsequently used as inputs for machine learning algorithms to identify arsenic concentrations. Results demonstrate that by selecting a subset of informative bands using NCA, accurate mineral identification can be achieved with a significantly reduced the size of dataset, enabling efficient processing and analysis. Comparison with other wavelength selection methods highlights the superiority of NCA in optimizing classification accuracy. Specifically, the identification accuracy showed 91.9% or more when utilizing 8 or more bands selected by NCA and was comparable to hyperspectral data analysis with 204 bands. The findings suggest potential for cost-effective implementation of multispectral cameras in mineral processing operations. Future research directions include refining machine learning algorithms, exploring broader applications across diverse ore types, and integrating hyperspectral imaging with emerging sensor technologies for enhanced mineral processing capabilities.
• Enhancing rock fragmentation assessment in mine blasting through machine learning algorithms: a practical approach
  Angesom Gebretsadik; Rahul Kumar; Yewuhalashet Fissha; Yemane Kide; Natsuo Okada; Hajime Ikeda; Arvind Kumar Mishra; Danial Jahed Armaghani; Yoko Ohtomo; Youhei Kawamura
  Discover Applied Sciences, 6, 5, Springer Science and Business Media LLC, 25 Apr. 2024, [Peer-reviewed]
  Scientific journal, Abstract
  
  The optimization of blasting operations greatly benefits from the prediction of rock fragmentation. The main factors that affect fragmentation are rock mass characteristics, blast geometry, and explosive properties. This paper is a step towards the implementation of machine learning and deep learning algorithms for predicting the extent of fragmentation (in percentage) in open pit mining. While various parameters can affect rock fragmentation, this study considers ten among them (i.e., spacing, drill hole diameter, burden, average bench height, powder factor, number of holes, charge per delay, uniaxial compressive strength, specific drilling, and stemming) to train and test the models. However, due to a weak correlation with rock fragmentation, drill diameter, average bench height, compressive strength, stemming, and charge per delay are eliminated to reduce model complexity. A total of 219 data sets having five input features including the number of holes, spacing, burden, specific drilling, and powder factor are used to develop the models. Machine learning models (random forest regression, support vector regression, and XG boost), as well as a deep learning model (neural network regression), are applied to develop a practical way that can optimize the prediction of fragmentation. This study employs performance measures such as R-squared, RMSE, MSE, MAPE, and MAE. The optimization of the model revealed promising results, indicating that the architecture 5-64-32-16-1 exhibits strong performance. Specifically, the model achieved mean squared error (MSE) values of 41.32 and 28.59 on the training and test datasets, respectively. The R² value for both training and test is 0.83. RFR is also performing well compared to SVR and XG boost with MSE values of 12.37 and 9.89 on training and testing data, respectively.in both sets, the R² value is 94%. Based on permutation importance and shapely plot values, it is observed that the powder factor has the highest impact, while the burden has the lowest impact on fragmentation.
• Development of Wide-Area Mineral Identification System Using Multispectral Camera Mounted on Drone for Beach Placer Deposits
  Hiromasa Nozaki; Natsuo Okada; Brian Bino Sinaice; Yoko Otomo; Youhei Kawamura
  Proceedings of the Second International Conference on Resources and Technology (RESAT 2023), 214, 232, Atlantis Press International BV, 29 Dec. 2023, [Peer-reviewed]
  English, International conference proceedings
• Applying nonnegative matrix factorization for underground mining method selection based on mining projects' historical data.
  Elsa Pansilvania Andre MANJATE; Yoko OHTOMO; Takahiko ARIMA; Tsuyoshi ADACHI; Bernardo Miguel BENE; Youhei KAWAMURA
  Int. J. Soc. Mater. Eng. Resour., 626, Oct. 2023, [Peer-reviewed]
  English, Scientific journal
• Low-Temperature Hydrothermal Synthesis of Chromian Spinel from Fe-Cr Hydroxides Using a Flow-Through Reactor
  Ohtomo, Y; Yang, J; Nishikata, M; Kawamoto, D; Kimura, Y; Otake, T; Sato, T
  Minerals, 12, 1110, 1110, 1110, MDPI AG, Aug. 2022, [Peer-reviewed], [Lead author]
  English, Scientific journal, Recent studies have suggested that a chromian spinel can be formed under natural hydrothermal conditions; however, the required conditions, process, and associated redistribution of Cr are still poorly understood. Here, chromian spinel formation was performed by Fe-Cr hydroxides alteration with an Fe2+(aq) supply at 150, 170, and 200 °C and 5 MPa simulating the diagenetic process. The flow-through system enabled the Fe2+(aq) supply to be leached from the magnetite by an acidic solution to synthesize Fe-Cr hydroxides as the starting material with two reaction cells, flow lines, heaters, and a high-performance liquid chromatography (HPLC) pump. The accuracy of the temperature measurement was confirmed based on the amorphous silica solubility. Mineralogical analysis of solid samples recovered from the reaction cell indicated that the chromian spinel was formed between 150 and 170 °C from Fe-Cr hydroxides through goethite with a simultaneous hematite formation, while Mössbauer spectra showed that a large quantity of Fe-Cr ferrihydrites still remained after the experiments probably because of the Cr addition to the stability of ferrihydrites. The Cr/Fe ratio of the chromian spinel was smaller than that of the bulk of the Fe-Cr ferrihydrites and equivalent to Cr-rich magnetite, suggesting a redistribution of Cr during the transformation from goethite to synthesized spinel under the hydrothermal conditions.
• Seasonal effects of natural attenuation on drainage contamination from artisanal gold mining, Cambodia: Implication for passive treatment
  Sereyroith Tum; Kanako Toda; Tatsuya Matsui; Ryosuke Kikuchi; Sitha Kong; Panha Meas; Unsovath Ear; Yoko Ohtomo; Tsubasa Otake; Tsutomu Sato
  Science of The Total Environment, 806, 150398, 150398, Elsevier BV, Feb. 2022, [Peer-reviewed]
  Scientific journal
• 地球表層環境における鉄の濃集と鉄鉱床の形成
  大竹 翼; 大友 陽子
  資源地質, 71, 2, 57, 73, 2021, [Peer-reviewed]
  Scientific journal
• Magmatic-Hydrothermal Processes Associated with Rare Earth Element Enrichment in the Kangankunde Carbonatite Complex, Malawi
  Frances Chikanda; Tsubasa Otake; Yoko Ohtomo; Akane Ito; Takaomi D. Yokoyama; Tsutomu Sato
  Minerals, 9, 7, 442, 442, 18 Jul. 2019, [Peer-reviewed]
  English, Scientific journal
• Deep-biosphere methane production stimulated by geofluids in the Nankai accretionary complex.
  Akira Ijiri; Fumio Inagaki; Yusuke Kubo; Rishi R Adhikari; Shohei Hattori; Tatsuhiko Hoshino; Hiroyuki Imachi; Shinsuke Kawagucci; Yuki Morono; Yoko Ohtomo; Shuhei Ono; Sanae Sakai; Ken Takai; Tomohiro Toki; David T Wang; Marcos Y Yoshinaga; Gail L Arnold; Juichiro Ashi; David H Case; Tomas Feseker; Kai-Uwe Hinrichs; Yojiro Ikegawa; Minoru Ikehara; Jens Kallmeyer; Hidenori Kumagai; Mark A Lever; Sumito Morita; Ko-Ichi Nakamura; Yuki Nakamura; Manabu Nishizawa; Victoria J Orphan; Hans Røy; Frauke Schmidt; Atsushi Tani; Wataru Tanikawa; Takeshi Terada; Hitoshi Tomaru; Takeshi Tsuji; Urumu Tsunogai; Yasuhiko T Yamaguchi; Naohiro Yoshida
  Science advances, 4, 6, eaao4631, Jun. 2018, [Peer-reviewed], [International Magazine]
  English, Scientific journal, Microbial life inhabiting subseafloor sediments plays an important role in Earth's carbon cycle. However, the impact of geodynamic processes on the distributions and carbon-cycling activities of subseafloor life remains poorly constrained. We explore a submarine mud volcano of the Nankai accretionary complex by drilling down to 200 m below the summit. Stable isotopic compositions of water and carbon compounds, including clumped methane isotopologues, suggest that ~90% of methane is microbially produced at 16° to 30°C and 300 to 900 m below seafloor, corresponding to the basin bottom, where fluids in the accretionary prism are supplied via megasplay faults. Radiotracer experiments showed that relatively small microbial populations in deep mud volcano sediments (102 to 103 cells cm-3) include highly active hydrogenotrophic methanogens and acetogens. Our findings indicate that subduction-associated fluid migration has stimulated microbial activity in the mud reservoir and that mud volcanoes may contribute more substantially to the methane budget than previously estimated.
• Data report: water activity of the deep coal-bearing basin off Shimokita from IODP Expedition 337
  Tanikawa, W; Ohtomo, Y; Snyder, G; Morono, Y; Kubo, Y; Iijima, Y; Noguchi, T; Hinrichs, K.-U; Inagaki, F
  Proceedings of the Integrated Ocean Drilling Program, 337, 2018, [Peer-reviewed]
  English, Symposium
• Microscopic observations of chromian spinel synthesized in a low temperature hydrothermal environment
  Nishikata Miu; Ohtomo Yoko; Otake Tsubasa; Kimura Yuki; Kawamoto Daisuke; Sato Tsutomu
  Abstracts of Annual Meeting of the Geochemical Society of Japan, 64, 310, 310, GEOCHEMICAL SOCIETY OF JAPAN, 2017
  Japanese,

• Microstructure and geochemistry of organic matters in banded iron formations, Moodies Group, Barberton Green stone Belt, South Africa
  Nakajima Ryo; Ohtomo Yoko; Otake Tsubasa; Kakegawa Takeshi; Sato Tsutomu
  Abstracts of Annual Meeting of the Geochemical Society of Japan, 64, 308, 308, GEOCHEMICAL SOCIETY OF JAPAN, 2017
  Japanese,

• Micro to nanoscale observations of carbonaceous matters in Archaean sedimentary rocks : Examples of > 3.7 Ga Isua Supracrustal Belt and 3.2 Ga banded iron formations, Moodies Group, Barberton Greensto
  Ohtomo Yoko; Nakajima Ryo; Otake Tsubasa; Kakegawa Takeshi
  Abstracts of Annual Meeting of the Geochemical Society of Japan, 64, 166, 166, GEOCHEMICAL SOCIETY OF JAPAN, 2017
  Japanese,

• Occurrence of Tourmaline in Metasedimentary Rocks of the Isua Supracrustal Belt, Greenland: Implications for Ribose Stabilization in Hadean Marine Sediments
  Shinpei Mishima; Yoko Ohtomo; Takeshi Kakegawa
  ORIGINS OF LIFE AND EVOLUTION OF BIOSPHERES, 46, 2-3, 247, 271, Jun. 2016, [Peer-reviewed]
  English, Scientific journal
• Recent progress in understanding of early earth biosphere
  Ohtomo Yoko
  Chikyukagaku, 50, 3, 177, 186, The Geochemical Society of Japan, 2016, [Peer-reviewed]
  Japanese, Scientific journal,

  When the first biosphere was formed on the early earth has been actively discussed recent years. Oldest biogenic graphite and microfossils have been repeatedly tested from early 2000s, due to unclear geological settings and discovery of abiotic production of organic compounds in native environments. Here, I introduce our discovery of novel graphite-rich metasedimentary rocks in the northwest of ca. 3.8 billion-years-old Isua Supracrustal Belt, western Greenland by detail geological investigation. Isotopic and nano-scale structural signatures of graphite show that graphite is originated in biogenic organic matter, providing further oldest evidence of biological activity in the ca. 3.8 Ga ocean. Evidence of early biosphere could be found outside of carbonaceous materials in old rocks. Banded iron formations, chemical marine sediments including Fe-bearing minerals, have been a subject of active research connecting redox state to biosphere on early earth's surface. Previous studies indicate that atmospheric oxygen increased at ca. 2.45 Ga (Great Oxidation Event: GOE),suggesting that oxygenic photosynthesizing bacteria have been flourished and emitted oxygen. However, more recent geological and geochemical records reveal that shallow part of ocean and atmosphere have been slightly oxidized before GOE, which evokes that oxygenic photosynthesizing bacteria was active earlier than that anticipated.

• CO2 emission and shallow-type methane hydrate decomposition experiment on deep-sea floor
  Yoko Ohtomo; Akira Ijiri; Yuki Morono; Yojiro Ikegawa; Hiroshi Suenaga; David Case; Hideaki Machiyama; Fujio Yamamoto; Shusaku Goto; Tatsuhiro Fukuba; Makoto Nagasawa; Masamitsu Matsumoto; Fumio Inagaki
  JAMSTEC Report of Research and Development, 20, 61, 71, Japan Agency for Marine-Earth Science and Technology, Mar. 2015, [Peer-reviewed]
  Japanese, Scientific journal, Increasing anthropogenic CO₂ in the atmosphere causes global warming and subsequent environmental changes, which may lead to an increase in natural disasters jeopardizing human society. Prompt technological development for CO₂ capture and sequestration is required in the international community. In this study, we performed CO₂ emission and shallow-type methane hydrate decomposition experiments at the Joetsu Knoll, offshore Joetsu, Niigata, Japan, as pilot studies to test feasibility of CO₂ sequestration and methane recovery using methane-CO₂ replacement in shallow-type methane hydrates. An isobaric cylinder pump and probe with a built-in heater ("Heat sonde") were developed to inject CO₂ in deep-sea, high-pressure conditions. Before injecting CO₂ into a methane hydrate located in deep-sea sediments, we attempted CO₂ emission directly into deep-seafloor. In the experiment, liquid CO₂ was emitted at the head of Heat sonde, however, the isobaric cylinder pump became clogged during operation. The result reveals that precipitates of CO₂ hydrate, which are generated during mixing of inflow seawater and outflow liquid CO₂, blocked flow lines of the isobaric cylinder pump and Heat sonde. This suggests that our developed instruments must be improved for future work. We also observed the collapse of an exposed methane hydrate layer at the seafloor upon contact with the Heat sonde in our experiment.
• Evidence for biogenic graphite in early Archaean Isua metasedimentary rocks
  Yoko Ohtomo; Takeshi Kakegawa; Akizumi Ishida; Toshiro Nagase; Minik T. Rosing
  NATURE GEOSCIENCE, 7, 1, 25, 28, Jan. 2014, [Peer-reviewed]
  English, Scientific journal
• Methanogenesis promoted by iron corrosion under deep subsurface condition
  Ohtomo Yoko; Ijiri Akira; Inagaki Fumio
  Abstracts of Annual Meeting of the Geochemical Society of Japan, 61, 41, 41, GEOCHEMICAL SOCIETY OF JAPAN, 2014
  Japanese, 地球温暖化の主要因である大気への人為的CO₂排出量削減技術の一つとして、メタン生成菌が行うCO₂のメタン変換を促進し、CO₂を再資源化しようとの試みが為されている。本研究では、鉄腐食に伴う水素生成でメタン生成菌がどの程度活性化するかを実験的に検証した。実験では、嫌気環境下でシリカビーズと鉄粉末（4－5g）を熱収縮チューブに詰めた反応カラムにメタン生成菌を植菌し、リアクターに設置した後CO₂と嫌気培地の混合流体を通過させた。カラムを通過した溶液は保圧状態で回収した後、溶存ガスの定量分析を行った。実験の結果、鉄添加カラムを通過した溶液に水素濃度及びメタン濃度の増加がみられ、メタン生成活性は0.2-3.7µmol/mL/dayであった。本研究成果は、CCS現場環境や類似の陸上CO₂変換施設において、CO₂還元型のメタン生成活性を促進させる手法の一つと考えられる。
• Biological CO2 conversion to acetate in subsurface coal-sand formation using a high-pressure reactor system
  Yoko Ohtomo; Akira Ijiri; Yojiro Ikegawa; Masazumi Tsutsumi; Hiroyuki Imachi; Go-Ichiro Uramoto; Tatsuhiko Hoshino; Yuki Morono; Sanae Sakai; Yumi Saito; Wataru Tanikawa; Takehiro Hirose; Fumio Inagaki
  Frontiers in Microbiology, 4, 2013
  Scientific journal
• Increase in acetate concentrations during sediment sample onboard storage: a caution for pore-water geochemical analysis
  Ijiri, A; Ohtomo, Y; Morono, Y; Ikehara, M; Inagaki, F
  Geochemical Journal, 47, 5, 567, 571, Terrapub, 2013, [Peer-reviewed]
  English, Scientific journal
• Contrast occurrence of banded iron formations in western part of Isua Spracrustal Belt, West Greenland
  Y. Ohtomo; T. Kakegawa
  GEOCHIMICA ET COSMOCHIMICA ACTA, 72, 12, A702, A702, Jul. 2008
  English, International conference proceedings
• Geochemistry and TEM observation of graphite in 3.8 Ga metasedimentary rocks in Isua Supracrustal Belt
  Y. Ohtomo; T. Kakegawa
  GEOCHIMICA ET COSMOCHIMICA ACTA, 71, 15, A735, A735, Aug. 2007
  English, International conference proceedings
• Heavy metal enrichment in Archean carbon-rich samples: Hint to early carbon-metal compounds for enzyme formation?
  T Kakegawa; Y Ohtomo; H Nakazawa; M Rosing
  GEOCHIMICA ET COSMOCHIMICA ACTA, 68, 11, A799, A799, Jun. 2004
  English, International conference proceedings
• Geological study of carbonatization of the 3.8 Ga Isua spracrustal Belt and abiological graphite generation.
  Ohtomo, Y; Kakegawa, T
  Proceedings of the Second International Workshop, Water Dynamics, 1, 217, 218, 2004
  English, International conference proceedings

• CHIME dating of monazite in graphitic schist, Isua Supracrustal Belt, Greenland
  Yoko Ohtomo; Takenori Kato, Nagoya University Bulletin of Chronological Research, 1, 63-65, Mar. 2017
  English, Report research institution
• 水分活性が海底下微生物活動に与える影響-IODP exp.337下北八戸沖堆積盆地掘削コア試料を用いた考察-
  谷川亘; 大友陽子; 諸野祐樹; SNYDER Glen; 久保雄介; 飯島慈裕; KAI-UWE Hinrichs; 稲垣史生, 日本地球惑星科学連合大会予稿集(Web), 2016, 2016
• CCS現場条件を再現するリアクターシステムの開発及びシステムを利用したCO₂資源化菌の培養実験
  大友陽子; 井尻暁; 堤正純; 井町寛之; 浦本豪一郎; 星野辰彦; 諸野祐樹; 酒井早苗; 斉藤由美; 谷川亘; 廣瀬丈洋; 稲垣史生; 池川洋二郎, 資源・素材学会北海道支部春季講演会講演要旨集, 2015, 2015
• 西グリーンランド・イスア表成岩帯におけるグラファイトの成因と生命の痕跡
  大友陽子; 掛川武; 石田章純, 日本地球化学会年会講演要旨集, 60th, 2013

• 生命起源の事典
  生命の起原および進化学会; 薮田 ひかる; 川村 邦男; 赤沼 哲史; 木賀 大介; 根本 直人; 古川 善博; 横堀 伸一, 第2章生き物の仕組みと変遷 ［環境と生物］地球太古の生命の痕跡 I：炭素質物質
  朝倉書店, 17 Apr. 2024, 9784254160789, [Contributor]
• 地球生命誕生の謎 カラー図解 アストロバイオロジー
  M・ガルゴー; H・マーティン; P; ロペス=ガルシア; T・モンメルル; R・パスカル 著; 薮田ひかる 監訳, 第6章編訳協力
  西村書店, Jun. 2021, [Supervisor]
• 季刊 資源と素材 2021 [春号] Vol.6（2021）No.2
  石の上にも三年…9 －宇宙探査と生命の起源－
  Apr. 2021
• 理系女子のライフプラン あんな生き方・こんな生き方 研究・結婚・出産みんなどうしてる?
  丸山美帆子; 長濱裕美; 大隅典子, 体験談及びコラム
  Jul. 2018, [Contributor]
• 環境と微生物の事典
  大友陽子, コラム「世界最古の微生物化石」
  朝倉書店, Jul. 2014, [Contributor]

• 酸性鉱山排水を利用したCO2鉱物化: 多成分溶液からの結晶成長
  長嶋剣; 大友陽子; 佐藤久夫
  第54回結晶成長国内会議 (JCCG-54), 13 Nov. 2025, Japanese, Oral presentation
  11 Nov. 2025 - 13 Nov. 2025, 46089006
• Performance Evaluation of Classical and Deep Learning Models in Hyperspectral Imaging: A Dataset-Centric Approach
  Natsuo Okada; Kaito Takizawa; Shion Wakae; Narihiro Owada; Brian Bino Sinaice; George Mathews; Yoko Ohtomo; Youhei Kawamura
  11th Asian Mining Congress, 31 Oct. 2025, English, Oral presentation
  30 Oct. 2025 - 31 Oct. 2025
• Occurrence of different Fe minerals in the same ferruginous section of the 3.2 Ga Moodies Group
  Yoko Ohtomo
  3rd BASE sampling and research workshop, 13 Oct. 2025, English, Public symposium
  13 Oct. 2025 - 15 Oct. 2025, 46088716
• ネイチャーポジティブに向けた休廃止鉱山管理のためのデジタルツイン技術の検討
  浜口 怜子; 大塚 尚広; 保高 徹生; 山縣 三郎; 黒嶋 章太; 新開 啓; 岡田 夏男; 大友 陽子; 川村 洋平
  資源・素材2025（札幌）, 04 Sep. 2025, Japanese, Oral presentation
  02 Sep. 2025 - 04 Sep. 2025
• 実学分野におけるメタバースを活用した教育システムの構築および遠隔モニタリングシステムへの応用
  茂見 隆博; 松尾 昴太郎; ジャムシェッド ラフマトフ; 岡田 夏男; 大友 陽子; 川村 洋平
  資源・素材2025（札幌）, 03 Sep. 2025, Japanese, Poster presentation
  02 Sep. 2025 - 04 Sep. 2025
• ドローン空撮および衛星データを活用したモンゴル・ゴビ砂漠のリチウム鉱石探査
  若江 史生; 滝澤 海斗; 石渡 翔丸; George Paul Mathews; 岡田 夏男; 菊池 亮佑; Gurbadam Erdene-Ochir; 大友 陽子; 川村 洋平; Jargalan Sereenen
  資源・素材2025（札幌）, 03 Sep. 2025, Japanese, Poster presentation
  02 Sep. 2025 - 04 Sep. 2025, 46088996
• 岩石薄片のデジタルスキャナー画像と機械学習を用いた鉱物判定システムによる堆積環境復元
  竹山 晃弘; 別府 祐哉; 戸谷田 光希; 大竹 翼; 岡田 夏男; 川村 洋平; 大友 陽子
  資源・素材2025（札幌）, 03 Sep. 2025, Japanese, Poster presentation
  02 Sep. 2025 - 04 Sep. 2025, 46088716
• ハイパースペクトルデータと機械学習を用いた石灰石と夾雑岩の判定
  横町 貢平; 前川 陽平; 滝澤 海斗; 若江 史生; 徳永 慎一; Mathews George; 岡田 夏男; 大友 陽子; 川村 洋平
  資源・素材2025（札幌）, 03 Sep. 2025, Japanese, Poster presentation
  02 Sep. 2025 - 04 Sep. 2025
• ハイパースペクトル画像と深層学習を用いた岩石試料中のヒ素濃度判別とCNNモデルの解釈性評価
  滝澤 海斗; 岡田 夏男; 黒木 宏忠; 後藤 佳子; George Mathews; 大友 陽子; 川村 洋平
  資源・素材2025（札幌）, 03 Sep. 2025, Japanese, Poster presentation
  02 Sep. 2025 - 04 Sep. 2025
• ブルー水素製造のための石炭地下ガス化燃焼制御を目的としたANNモデルによる温度推定と放射基底関数を用いた３次元可視化手法
  竹内 優太; 板倉 賢一; 出口 剛太; 濱中 晃弘; 岡田 夏男; 大友 陽子; 川村 洋平
  資源・素材2025（札幌）, 03 Sep. 2025, Japanese, Poster presentation
  02 Sep. 2025 - 04 Sep. 2025
• 地中熱ヒートポンプ導入支援のための遠隔モニタリング・人材育成システムの開発
  松尾 昂太郎; 茂見 隆博; ジャムシェド ラフマトフ; スオリネニ フィデリス; 岡田 夏男; 大友 陽子; 川村 洋平
  資源・素材2025（札幌）, 03 Sep. 2025, Japanese, Poster presentation
  02 Sep. 2025 - 04 Sep. 2025
• トンネル発破における余掘り予測AIの精度向上に向けた割れ目角度抽出手法の確立
  中根 光太郎; 中澤 雄奈; キョ ユリン; 後藤 佳子; 黒木 宏忠; 川村 洋平; 大友 陽子; 岡田 夏男
  資源・素材2025（札幌）, 03 Sep. 2025, Japanese, Poster presentation
  02 Sep. 2025 - 04 Sep. 2025
• トンネル発破における余掘り量及び発生箇所推定のためのドリルエネルギー解析による切羽背面の情報の可視化
  中澤 雄奈; Xu Yulin; 中根 光太郎; 翟 思敏; 岡田 夏男; 大友 陽子; 川村 洋平
  資源・素材2025（札幌）, 03 Sep. 2025, Japanese, Poster presentation
  02 Sep. 2025 - 04 Sep. 2025
• Geology-Constrained Data Generation for Tunnel Construction Using Tabular GANs
  Yulin Xu; Yuna Nakazawa; Natsuo Okada; Yoko Ohtomo; Youhei Kawamura
  MMIJ 2025, Sapporo, 03 Sep. 2025, English, Poster presentation
  02 Sep. 2025 - 04 Sep. 2025
• Rare Earth Element-related heavy mineral sand identification using AI
  Okhala Muacanhia; Natsuo Okada; Yoko Ohtomo; Youhei Kawamura
  MMIJ 2025, Sapporo, 02 Sep. 2025, English, Oral presentation
  02 Sep. 2025 - 04 Sep. 2025
• Mineralogical Composition and Trace Element Distribution in Coal Minerals for Environmental Pollution Assessment
  Jackson Ezekiel Birore; Yuna Nakazawa; Natsuo Okada; Angesom Gebretsadik; Yoko Ohtomo; Youhei Kawamura
  MMIJ 2025, Sapporo, 02 Sep. 2025, English, Oral presentation
  02 Sep. 2025 - 04 Sep. 2025
• Hybrid AI–Geostatistical Modeling for 3D Ash Prediction and Zoning in Sparse Drillhole Environments: A Case Study Integrating 3D Block Model and Machine Learning
  Angesom Gebretsadik Abraha; Natsuo Okada; Ryo Itano; Yoko Ohtomo; George Mathews; Youhei Kawamura
  MMIJ 2025, Sapporo, 02 Sep. 2025, English, Oral presentation
  02 Sep. 2025 - 04 Sep. 2025
• Training of the Fluid Inclusion Heating Freezing system
  Yoko Ohtomo
  M-JEED Visiting Scholar Program, English, Public discourse
  17 Jul. 2025 - 19 Jul. 2025, [Invited]
• Abiotic Catalytic Oxidation of Manganese in Acid Mine Drainage: Mechanisms and Remediation Potential
  Joseph Godirilwe; Kenta Hasegawa; Ryosuke Kikuchi; Frances Chikanda; Shingo Tomiyama; Yoko Ohtomo; Tsutomu Sato; Tsubasa Otake
  Goldschmidt 2025 Conference, 11 Jul. 2025, English, Oral presentation
  06 Jul. 2025 - 11 Jul. 2025
• Occurrence of different Fe minerals in a same ferruginous section in the 3.2Ga Moodies Group, Barberton Greenstone Belt
  Koki Toyata; Tsubasa Otake; Akizumi Ishida; Yoko Ohtomo; Ryosuke Kikuchi; Takeshi Kakegawa
  Goldschmidt 2025 Conference, 10 Jul. 2025, English, Poster presentation
  06 Jul. 2025 - 11 Jul. 2025, 46088716
• Evaluation of carbon dioxide removal potential of various rocks for enhanced rock weathering as a negative emission technology
  Shuai Wang; Knight Yamashita; Hkaung Htut san; Tsubasa Otake; Ryosuke Kikuchi; Yoko Ohtomo; Frances Chikanda; Tsutomu Sato
  Goldschmidt 2025 Conference, 07 Jul. 2025, English, Poster presentation
  06 Jul. 2025 - 11 Jul. 2025
• Geochemical Modeling of Acid Mine Drainage Treatment Integrated with Enhanced Basalt Weathering as Carbon Dioxide Removal Technology
  Monthicha Rawangphai; Nono Kitmosuki; Fugo Nakamura; Hkaung Htut san; Frances Chikanda; Ryosuke Kikuchi; Yoko Ohtomo; Tsubasa Otake; Tsutomu Sato
  Goldschmidt 2025 Conference, 07 Jul. 2025, English, Oral presentation
  06 Jul. 2025 - 11 Jul. 2025
• 偏光顕微鏡デジタルスキャナーを用いた苦鉄質岩中の鉱物相の定量解析
  別府祐哉; 菊池亮佑; 大友陽子; 大竹 翼
  資源地質学会第 74 回年会学術講演会, 27 Jun. 2025, Japanese, Poster presentation
  25 Jun. 2025 - 27 Jun. 2025
• Geology and mineralogy of lithium mineralization in the central east part of Mongolia
  E. Gurbadam; S. Jargalan; Y. Ohtomo; R. Kikuchi; S. Wakae
  The 74th Annual Meeting of the Society of Resource Geology, 27 Jun. 2025, English, Poster presentation
  25 Jun. 2025 - 27 Jun. 2025
• ハイパースペクトル画像と深層学習によるNiラテライト鉱床の風化層の判別
  古川皓一; 岡田夏男; 菊池亮佑; 大友陽子; 川村洋平; 大竹 翼
  資源地質学会第 74 回年会学術講演会, 26 Jun. 2025, Japanese, Oral presentation
  25 Jun. 2025 - 27 Jun. 2025
• マルチスペクトルカメラ搭載ドローンによるリチウム鉱石の探査システム開発
  若江史生; 滝澤海斗; 岡田夏男; 石渡翔丸; 菊池亮佑; Erdene-Ochir Gurbadam; 大友陽子; 川村洋平; Jargalan Sereenen
  資源地質学会第 74 回年会学術講演会, 26 Jun. 2025, Japanese, Oral presentation
  25 Jun. 2025 - 27 Jun. 2025, 46088996
• Identification of Lithium Ore Distributed in the Gobi Desert of Mongolia Using Multispectral Drone
  Shion Wakae; Kaito Takizawa; Natsuo Okada; Tobimaru Ishiwata; Ryosuke Kikuchi; Yoko Ohtomo; Youhei Kawamura
  Japan Geoscience Union Meeting 2025, 30 May 2025, English, Poster presentation
  25 May 2025 - 30 May 2025, 46088996
• Hyperspectral imagery machine learning analyser app for mineral identification: APiS (AI powered intelligence spectrum analyser)
  Natsuo Okada; Kaito Takizawa; Okhala Muacanhia; Yoko Ohtomo; Youhei Kawamura
  Japan Geoscience Union Meeting 2025, 30 May 2025, English, Poster presentation
  25 May 2025 - 30 May 2025
• 酸性鉱山廃水を利用したCO2鉱物化：多成分溶液からの結晶成長
  長嶋 剣; 大友 陽子
  日本地球惑星科学連合2025年大会, 25 May 2025, Japanese, Oral presentation
  25 May 2025 - 30 May 2025
• How are the mineral resources required for green technology produced in nature?
  Yoko Ohtomo
  J-PEAKS Workshop of Non-Equilibrium Science, 07 May 2025, Japanese, Nominated symposium
  07 May 2025 - 08 May 2025, 51587127
• 低温蛇紋岩化反応時の水素生成に与える溶存イオンの影響
  長島 康裕; 大竹 翼; 菊池 亮佑; 大友 陽子; 佐藤 努
  資源・素材学会2025年度春季大会, 14 Mar. 2025, Japanese, Oral presentation
  12 Mar. 2025 - 14 Mar. 2025
• 環境調和型鉱山開発に向けた地質学と情報学の融合
  大友陽子
  工学アカデミー北海道支部 第1回研究発表会, 21 Jan. 2025, Japanese, Invited oral presentation
  [Invited]
• 資源の安定的な確保に向けたアジア・アフリカにおける共同研究の紹介
  大友陽子
  令和6年度大学学部説明会, 06 Nov. 2024, Japanese, Public discourse
• Formation process of carbonate minerals in iron formations deposited in a shallow ocean 3.2 billion years ago
  K. Toyata; R. Sugiura; Y. Ohtomo; T. Otake
  International Symposium on Chemical and Biological Hazards on One Health: Toward Sustainable Mineral Development and Pollution Monitoring, University of Botswana, Gaborone, Botswana, 09 Oct. 2024, English, Poster presentation
• 湯の花の結晶成長
  大友陽子
  第43回結晶成長討論会「先端可視化手法と結晶成長素過程」, 登別, 北海道, 13 Sep. 2024, Japanese, Public discourse
  12 Sep. 2024 - 14 Sep. 2024
• Abiotic catalytic reaction dominance in manganese removal from an acid mine water
  J. Godirilwe; T. Otake; F. Chikanda; R. Kikuchi; Y. Ohtomo; S. Tomiyama; T. Sato
  International Geological Congress 2024, Busan, Korea, 28 Aug. 2024, English, Oral presentation
• Identification of high-grade Ni laterite ores using hyperspectral imagining and deep learning
  K. Furukawa; N. Okada; R. Kikuchi; Y. Ohtomo; T. Otake; Y. Kawamura
  International Geological Congress 2024, Busan, Korea, 28 Aug. 2024, English, Poster presentation
• Wide-area ore deposits exploration system using a drone equipped with a multispectral camera
  Yoko Ohtomo; Hiromasa Nozaki; Natsuo Okada; Youhei Kawamura
  Japan Geoscience Union Meeting 2024, 30 May 2024, English, Poster presentation
  26 May 2024 - 31 May 2024, [Invited]
• Passive treatments learnt from natural attenuation processes
  Ohtomo, Y.
  The Symposium of Passive Treatment for Mine Wastewater. Joint sponsorship of JICA and Ministry of Mines and Energy, Cambodia. Kizuna follow-up symposium, Phnom Penh, Cambodia, 29 Apr. 2024, English, Keynote oral presentation
  [Invited]
• 風化促進によるネガティブエミッション技術に利用する岩石の二酸化炭素除去ポテンシャル評価
  山下騎士; 肝付のの; SAN Hkaung Htu; CHIKANDA Frances; 野呂田晋; 菊池亮佑; 大友陽子; 大竹翼; 佐藤努
  資源・素材学会春季大会, 18 Mar. 2024, Japanese, Oral presentation
  17 Mar. 2024 - 19 Mar. 2024
• バッテリーメタルの鉱床学
  大友陽子
  札幌×秋田ゼロカーボンワークショップ, 秋田大学, 06 Dec. 2023, Japanese
  [Invited]
• Fe-silicate and -carbonate formations at C-steel-compacted bentonite interface hinders buffer degradation in high-level radioactive waste disposal.
  Kikuchi, R; Fujimura, T; Sato, T; Otake, T; Ohtomo, Y; Goto, T; Suzuki, S; Taniguchi, N; Suzuki, H
  Water-Rock Interaction WRI-17, Sendai, Miyagi, Japan, Aug. 2023, English, Oral presentation
• Geochemical signatures recorded by trace element compositions in magnetite in Archean Banded Iron Formations
  Matsukawa, H; Otake, T; Ohtomo, Y; Kon, Y; Sato, T; Kakegawa, T
  Water-Rock Interaction WRI-17, Sendai, Miyagi, Japan, Aug. 2023, English, Poster presentation
• Mechanism of manganese oxidation and removal from acid mine drainage wastewater
  Godirilwe, G. J; Otake, T; Tomiyama, S; Chikanda, F; Ohtomo, Y; Sato, T
  Water-Rock Interaction WRI-17, Sendai, Miyagi, Japan, Aug. 2023, English, Poster presentation
• Development of a Different Altitude Spectral Image Registration Protocol Utilizing Digital Twin.
  Okada, N; Toriya, H; Arima, T; Ohtomo, Y; Shigemi, T; Rasoanindriana, A; Nozaki, H; Nakamura, S; Kawamura, Y
  Water-Rock Interaction WRI-17, Sendai, Miyagi, Japan, Aug. 2023, English, Oral presentation
• 3.2 Ga shallow ocean environment recorded in banded iron formation by chromium concentration, Moodies Group, Barberton Greenstone Belt, South Africa.
  Ohtomo, Y; Matsukawa, H; Nagashima, Y; Otake, T; Kakegawa, T; Sato, T
  Water-Rock Interaction WRI-17, Aug. 2023, English, Oral presentation
• Fe and Mg isotope fractionations in ferruginous sedimentary rocks from the ~3.2 Ga Moodies Group, Barberton Greenstone Belt, South Africa.
  Otake, T; Sugiura, R; Shin, K; Ohtomo, Y; Kakegawa, T; Sato, T
  Goldschmidt Conference, Lyon, France, 13 Jul. 2023, English, Oral presentation
  45202009
• Transparent carbon films containing graphene in 3.2 Ga sedimentary rocks in the Moodies group, Barberton Greenstone Belt, South Africa.
  Ohtomo, Y; Otake, T; Kakegawa, T; Sato, T
  Goldschmidt Conference, Lyon, France, 10 Jul. 2023, English, Oral presentation
  13464449
• Development of Wide-Area Mineral Identification System Using Multispectral Camera Mounted on Drone for Beach Placer Deposits.
  Nozaki, H; Okada, N; Sinaice, B. B; Otomo, Y; Kawamura, Y
  The Second International Conference on Resources and Technology (RESAT 2023), English, Oral presentation
  19 Jun. 2023 - 20 Jun. 2023
• Evidence for biogenic graphite in early Archean Isua metasedimentary rocks
  Yoko Ohtomo
  Special Lecture in Mongolian University of Science and Technology, 02 Mar. 2023, English, Public discourse
  44711493, [Invited]
• 低温蛇紋岩化反応における水素生成再現のための地球化学モデリング
  菅原 あすか; 東野 駿太; 大竹翼; 大友 陽子; 佐藤努
  日本地球化学会第69会年会, Poster presentation
  05 Sep. 2022 - 12 Sep. 2022
• Iron precipitation and associated microbial activities in Ainai and Shojin river mine drainages, Japan
  Yoko Ohtomo; Tatsuya Matsui; Frances Chikanda; Sereyroith Tum; Tsubasa Otake; Tsutomu Sato
  Goldschmidt Conference, 2022, Hawaii, Poster presentation
  07 Jul. 2022 - 17 Jul. 2022
• 南アフリカ・ムーディーズ層群中の縞状鉄鉱層に産する磁鉄鉱の微量元素組成
  松川春樹; 大友陽子; 大竹 翼; 昆 慶明; 佐藤 努; 掛川 武
  資源地質学会第71回年会学術講演会, 30 Jun. 2022, Poster presentation
• Iron precipitation and associated microbial activities in acid mine drainages of Ainai and Shojin river mine
  Yoko Ohtomo; Tatsuya Matsui; Frances Chikanda; Sereyroith Tum; Tsubasa Otake; Tsutomu Sato
  02 Jun. 2022, Poster presentation
• Geochemical behavior of Fe and Mg in the Moodies Banded Iron Formations, Barberton Greenstone Belt, South Africa
  Ryohei Sugiura; Tsubasa Otake; Yoko Ohtomo; Tsutomu Sato; Ki-Cheol Shin
  JpGU, 2022, 02 Jun. 2022, Poster presentation
• 相内鉱山及び精進川鉱山坑廃水路における微生物叢と鉄沈殿物形成
  大友陽子; 松居達也; Frances Chikanda; Sereyroith Tum; 大竹翼; 佐藤努
  Webシンポジウム「休廃止鉱山のグリーン・レメディエーションに関わる研究の最前線」, 01 Mar. 2022, Japanese, Invited oral presentation
  13464451, [Invited]
• Microbial communities and Iron-bearing precipitates in the passive treatment sites of Ainai and Shojingawa mines
  大友 陽子; 松居 達也; チカンダ フランセス; セレイロイス タム; 大竹 翼; 佐藤 努
  資源・素材2021, 14 Sep. 2021, Oral presentation
• Geochemical modeling of a natural remediation of an acid mine drainage from an abandoned mine in northern Japan.
  S. Tum; F. Chikanda; T. Matsui; Y. Ohtomo; T. Otake; R. Kikuchi; S. Norota; T. Sato
  Goldschmidt 2021 (online), 07 Jul. 2021, Poster presentation
• Fe isotope signatures for oxidative precipitation of ferrous iron in ~3.2 Ga shallow ocean from the Moodies Group, Barberton Greenstone Belt, South Africa.
  R. Sugiura; T. Otake; Y. Ohtomo; T. Sato; T. Kakegawa
  Goldschmidt 2021 (online), 07 Jul. 2021, Oral presentation
• Geochemical characterization of rivers contaminated by acid mine drainage from an abandoned mine in northern Japan.
  S.Tum; T. Matsui; F. Chikanda; R. Kikuchi; Y. Ohtomo; T. Otake; S. Norota; T. Sato
  JpGU 2021, 03 Jun. 2021, English
  30 May 2021 - 06 Jun. 2021
• 32億年前に形成した縞状鉄鉱層中の鉄同位体比に記録された太古代浅海域における鉄の酸化沈殿プロセス.
  杉浦 遼平; 大竹 翼; 山内 大蔵; 大友 陽子; 佐藤 努
  第10回同位体環境学シンポジウム, 18 Dec. 2020, English
• A Process Model of Natural Attenuation of Heavy Metals in a Stream Contaminated by Acid Mine Drainage from Artisanal Gold Mining in Cambodia.
  S. Tum; T. Sato; T. Matsui; S. Kong; Y. Ohtomo; R. Kikuchi; T. Otake
  JpGU-AGU Joint Meeting 2020, English
  12 Jul. 2020 - 16 Jul. 2020
• Depositional setting and biological activity highlighted by Cr concentration, 3.2Ga Moodies Group, Barberton Greenstone Belt.
  Ohtomo, Y., Yamauchi, D., Otake, T. and Sato, T.
  JpGU-AGU Joint Meeting 2020, English
  12 Jul. 2020 - 16 Jul. 2020
• 32億年前に形成した南アフリカ・バーバトン緑色片岩帯ムーディーズ縞状鉄鉱層における鉄同位体分別.
  杉浦 遼平; 大竹 翼; 山内 大蔵; 大友 陽子; 佐藤 努
  JpGU-AGU Joint Meeting 2020, Japanese
  12 Jul. 2020 - 16 Jul. 2020
• 32億年前縞状鉄鉱層中有機物の微細構造観察及び微小領域分析
  大友陽子
  北海道大学大学院工学研究院 ナノマイクロマテリアルラボ・ユーザーズミーティング, 23 Oct. 2019, Japanese
  [Invited]
• Micro to nanostructures of carbonaceous materials in 3.2 Ga banded iron formations, Moodies Group, Barberton Greenstone Belt, South Africa
  Ohtomo, Y; Nakajima, R; Otake, T; Kakegawa, T; Sato, T
  Goldschmidt Conference, Boston, USA, 17 Aug. 2018, English, Oral presentation
  [International presentation]
• Nano-scale observation of Cr-bearing spinel synthesized in a seafloor hydrothermal condition
  Nishikata, M; Ohtomo, Y; Otake, T; Kimura, Y; Kawamoto, D; Sato, T
  Goldschmidt Conference, Boston, USA, 15 Aug. 2018, English, Poster presentation
  [International presentation]
• The role of multi-stage processes on ree enrichment in Kangankunde carbonatites, Malawi.
  F. Chikanda; T. Otake; Y. Ohtomo; T. Sato
  Goldschmidt;Hynes Convention Center;Boston, USA;August, 14 Aug. 2018, Oral presentation
• Hydrothermal synthesis of chormian spinel from iron and chromium hydroxides using a flow-through apparatus.
  T. Otake; M. Nishikata; T. Ohtomo; Y. Kimura; D. Kawamoto; T. Sato
  American Chemical Society National Meeting;The Ernest E. Morial;Convention Center;New Orleans;USA, 18 Mar. 2018, Oral presentation
• Micro to nanoscale observations of carbonaceous matters in 3.2 Ga Banded iron formations, Sheba Gold mine, Moodies Group, Barberton Greenstone Belt and 3.7 Ga schist, Isua Supracrustal Belt.
  Ohtomo, Y; Nakajima, R; Otake, T; Kakegawa
  Goldschmidt Conference, Aug. 2017, English, Poster presentation
  [International presentation]
• Petrographic and geochemical characteristics of monazite and zircon associated with biogenic graphite in > 3.7 Ga metasedimentary rocks, Isua Supracrustal Belt, West Greenland.
  Ohtomo, Y; Kato, T; Otake, T
  Goldschmidt Conference, Yokohama, 29 Jun. 2016, English, Poster presentation
  [International presentation]
• Biosignature recorded in geochemical correlations between organic matter and Fe-bearing minerals in 3.2Ga banded iron formations, Barberton Greenstone Belt, South Africa
  Yoko Ohtomo
  Goldschmidt Conference, Yokohana, 29 Jun. 2016, English, Poster presentation
  [International presentation]
• グリーンランド・イスア地域の岩石から読み解く約38億年前の生命圏
  大友陽子
  第28回名古屋大学宇宙地球環境研究所 年代測定研究部シンポジウム, 28 Jan. 2016, Japanese, Invited oral presentation
  [Invited], [Domestic Conference]
• 地下深部に自生するCO2資源化菌の高圧リアクター培養
  大友陽子
  北海道資源・素材フォーラム2015 〜資源・エネルギー・環境の諸問題に微生物機能を利用した最新の技術動向と未来〜, 11 Dec. 2015, Japanese, Invited oral presentation
  [Invited], [Domestic Conference]
• 約38億年前の岩石に残された最古の生命の痕跡
  大友陽子
  第45回結晶成長国内会議 (NCCG-45) 結晶成長基礎・評価分科会, バイオ有機文科会 合同シンポジウム 「地球・惑星・生命における結晶成長」, 19 Oct. 2015, Japanese, Invited oral presentation
  [Invited], [Domestic Conference]
• Carbonate vein formation in banded iron formations and metabasalts associated with CO2 metasomatism, Isua Supracrustal Belt, West Greenland
  Ohtomo, Y; Kakegawa, T
  Goldschmidt Conference, Prague, 16 Aug. 2015, English, Poster presentation
  [International presentation]
• The oldest remnant of life in 3.8 Ga old early Archaean rocks
  Yoko Ohtomo
  JpGU, 2014, 30 Apr. 2014, Japanese, Invited oral presentation
  [Invited], [Domestic Conference]
• Biological CO2 conversion to acetate in subsurface coal-sand formation using a high-pressure reactor system.
  Ohtomo, Y; Ijiri, A; Ikegawa, Y; Tsutsumi, M; Imachi, H; Uramoto, G; Hoshino, T; Morono, Y; Tanikawa, W; Hirose, T; Inagaki, F
  AGU, San Francisco, 2013, English, Poster presentation
  [International presentation]
• Evidence for biogenic graphite in early Archaean Isua metasedimentary rocks.
  Ohtomo, Y; Kakegawa, T; Ishida, A; Rosing, M. T
  The International Biogeoscience Conference, Nagoya, Japan, 2013, English, Oral presentation
  [International presentation]
• Energetic habitability and biogeochemical carbon cycle in a deep-sea mud-volcano subsutface.
  Ijiri, A; Ohtomo, Y; Inagaki, F
  Microenergy 2012, 2nd International Workshop on Microbial Life under Extreme Energy Limitation, Aarhus, Denmark, 2012, English, Poster presentation
  [International presentation]
• Contrast occurrence of banded iron formation in western part of Isua Spracrustal Belt, Greenland.
  Ohtomo, Y; Kakegawa, T
  Goldschmidt Conference, Vancouver, Canada, 2008, English, Poster presentation
  [International presentation]
• Geochemistry and TEM observation of graphite in 3.8 Ga metasedimentary rocks in Isua Supracrustal Belt.
  Ohtomo, Y; Kakegawa, T
  Goldschmidt Conference, Cologne, Germany, 2007, English, Poster presentation
  [International presentation]
• Metamorphic and metasomatic effects on carbon isotope and REE compositions in 3.8 Ga metasedimentary rocks in Isua Supracrustal Belt.
  Yoko Ohtomo
  19th general meeting of the international mineralogical association, expansion to nano, bio and planetary worlds, 23 Jul. 2006, English, Poster presentation
  [International presentation]
• Geological study of carbonatization of the 3.8 Ga Isua spracrustal Belt and abiological graphite generation.
  Ohtomo, Y; Kakegawa, T
  Water Dynamics, Sendai, Japan, 2004, English, Poster presentation
  [International presentation]
• Heavy metal enrichment in Archean carbon-rich samples: Hint to early carbon-metal compounds for enzyme formation?
  Kakegawa, T; Ohtomo, Y; Nakazawa, H; Rosing, M
  Goldschmidt Conference, Copenhagen, Denmark, 2004, English, Poster presentation
  [International presentation]

• 環境化学, 2024年, 学士課程, 工学部
• 資源情報学, 2024年, 学士課程, 工学部

• Jan. 2023 - Present
  資源地質学会
• Oct. 2018 - Present
  一般社団法人 資源・素材学会
• 2011 - Present
  American Geophysical Union
• THE GEOCHEMICAL SOCIETY OF JAPAN
• JAPAN GEOSCIENCE UNION

• スマートマイニング+による環境破壊を引き起こさない持続可能な環境調和的鉱山開発システムの構築
  地球規模課題対応国際科学技術協力プログラム
  Apr. 2024 - Mar. 2029
  川村洋平
  科学技術振興機構, 北海道大学, Coinvestigator
• 自然に学ぶ非平衡状態の学理構築と高効率次世代材料開発拠点の形成
  J-PEAKS連携研究プラットフォーム事業
  Apr. 2025 - Mar. 2028
  日本学術振興会, 北海道大学, Coinvestigator
• 科学掘削コア試料を用いた32億年前の金属元素循環と酸化還元環境の解明
  科学研究費助成事業
  Apr. 2024 - Mar. 2028
  大竹 翼
  日本学術振興会, 基盤研究(A)分担, 北海道大学, 24H00436
• 休廃止鉱山環境を活用した岩石風化促進による二酸化炭素の鉱物固定
  科学研究費助成事業
  Apr. 2024 - Mar. 2027
  大友 陽子
  日本学術振興会, 基盤研究(B), 北海道大学, 24K01411
• モンゴルのリチウム鉱石を対象とした次世代型鉱山開発モデルの提案
  科学研究費補助金
  Apr. 2024 - Mar. 2026
  日本学術振興会, 二国間交流事業 オープンパートナーシップ共同研究, 北海道大学, Principal investigator
• Understanding biosphere-hydrosphere-atmosphere-lithosphere interactions 3.2 billion years ago with an international continental drilling program
  Grants-in-Aid for Scientific Research
  Apr. 2020 - Mar. 2024
  大竹 翼; 石田 章純; 杉谷 健一郎; AGANGI ANDREA; 掛川 武; 大友 陽子
  R4年度はR3年度から引き続きバーバトンにて科学掘削が行われた。最後の掘削コアとなるsite 1では500m近くの掘削に成功し、ムーディーズ層群のうち最下層であるMdS1層の一部化学堆積物を含む砕屑性堆積岩を採取することができた。さらに上部のMdS2層では今回の掘削コアの中では最も深海部で堆積したと考えられる頁岩層の採取にも成功した。日本チームも11月に現地を訪れ、掘削後の現地の様子や周辺露頭の調査を行った。掘削コアは計8本, 総延長は3131mにわたる。32億年前の最古の沿岸域から深海底の砕屑性・化学性の堆積岩を網羅する新鮮な岩石試料を採取できたことは大きな科学的成果だと言える。国際共同プロジェクトとして共通の成果とするため、現地の代表チームにて掘削コアの岩石学的な記載が行われた後、コアを２分割し、半分はドイツ、ベルリンにあるBGRのコアセンターに輸送された。現在は非破壊分析による全岩化学組成のデータを収集しているところであり、岩石記載データと合わせて解析を行う。これまでに採取している露頭や稼行中の鉱山で採取済みの岩石試料では、これまで鉄やクロムの安定同位体比はバルク試料での分析のみを行っていたが、ホスト鉱物ごとの同位体比を明らかにするために、磁力選別や比重選別などの物理的な手法によって鉱物の選別を試みた。しかしながら、鉱物の粒径が小さすぎたため100%に近い鉱物の単体分離は困難であることが分かった。今後は化学的な抽出方法を検討する必要がある。
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Hokkaido University, 20H00184
• Constrains on timings of cyanobacterial and eukaryotic evolutions based on innovative biomarker analyses
  Grants-in-Aid for Scientific Research
  Apr. 2019 - Mar. 2023
  Sugitani Kenichiro
  Unfortunately, we were not able to detect the biomarkers that we initially intended in this study. However, thorough morphological analysis of microfossils in specimens in petrographic thin sections and maceration products, we found that large (~100 micron) lenticular microfossils form complex colonies that can only be attributed to intercellular physical communication. This suggests that they had a highly organized cytoskeleton. Similar cytoskeletons have been shown to hold for large sack-like fossils that can reach over 200 microns, allowing us to take a step closer to understanding the eukaryotic nature of these large microfossils. In addition, we were able to build a framework for the classification system of a series of Archean microfossil groups discovered by the applicant.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Nagoya University, 19H02013
• Microbial ecosystem involved in the genesis of banded iron formation at ca. 3.2 Ga
  Grants-in-Aid for Scientific Research
  Apr. 2019 - Mar. 2023
  Ohtomo Yoko
  Microorganisms involved in the iron oxidation of Banded Iron Formation before ca. 2.4 Ga Great Oxidation Event (GOE) has been actively discussed in Early Earth Science. The objective of this study is to give constraints on the microbial species by micro to nano morphological/structural observations, micro-spectrometry, carbon and nitrogen stable isotope analyses of carbonaceous materials in the 3.2 Ga BIF, Moodies Group, Barberton Greenstone Belt, South Africa with petrological data.
  Morphological observations of carbonaceous materials extracted by micro-sampling and acid-treatment suggest that multiple microbial species flourished before the GOE and each microbial community fluctuated with the transition of the iron oxidation conditions of the BIF. The interiors of the carbonaceous materials are not like microfossil-like structures but showed aggregates of micro-grains covered by thin films, containing graphene structures.
  Japan Society for the Promotion of Science, Grant-in-Aid for Early-Career Scientists, Hokkaido University, 19K15486
• 大気からCO2を効率的に回収・固定化する新たな風化促進技術“A-ERW”の開発
  ムーンショット型開発研究事業
  Sep. 2022
  中垣隆雄, 早稲田大学
  国立研究開発法人新エネルギー・産業技術開発機構, 北海道大学, Coinvestigator not use grants
• 秋田県相内鉱山坑廃水のパッシブトリートメントにおける微生物学的プロセスの理解
  Experimental research grant
  Apr. 2019 - Mar. 2021
  Yoko Ohtomo
  Japan mining industory association, Principal investigator, Competitive research funding
• 一般共同研究
  Apr. 2017 - Mar. 2018
  大友陽子
  名古屋大学宇宙地球環境研究所, Principal investigator, Competitive research funding
• 約３８億年前の地球表層希土類金属元素循環と生命圏の解明
  科学研究費助成事業
  Apr. 2015 - Mar. 2018
  大友 陽子
  本研究では約38億年前に形成したイスア表成岩帯に産する生物由来graphiteと共存する希土類鉱物 (zircon, monazite, xenotime)の年代測定・組成分析により、当時の微生物生態系に制約を与えることを目的とした。これら希土類鉱物はサイズ数μm～10μmと非常に小さい為、微小領域分析に強いCHIME年代法での分析を試みた。希土類鉱物はしばしばクラックが入っている為、CHIME法であってもビームがうまく当たらず正確な測定ができないという問題点が浮上した。そこで可能な限り多点分析を行い、妥当な測定値のみを採用することとした。測定の結果、zirconは過去の研究で示されたイスア表成岩帯の形成年代 (Nutman et al., 2009)と同等かそれよりも古く、当時の砕屑物由来であり変成作用の影響は少ないと考えられる。一方でxenotime及びmonaziteの年代は約37億年前と約27億年前の2箇所にピークを持つことがわかったが、CHIME年代の誤差を考えると、本結果のみでxenotimeやmonaziteの初生年代を決定することはできない。そこでgraphiteとmonaziteの微小領域における位置関係からその成因を割り出すため、monazite、基質およびgraphite凝集体が共存する部分を集束イオンビームで切断して薄膜を作製し、透過型電子顕微鏡による組織観察を行った。するとmonazite結晶中にもgraphite及び石英の包有物が観察された。このgraphiteの結晶格子は乱れており、生物由来graphiteに似た特徴を示した。この産状は形成過程でgraphiteのもととなった生物の死骸や石英がmonazite中に取り込まれた、すなわちモナザイトの前駆物質が当時の海洋で沈殿したことを示唆していると考えられる。
  日本学術振興会, 特別研究員奨励費, 北海道大学, 15J00507
• 一般共同研究
  Apr. 2016 - Mar. 2017
  大友陽子
  名古屋大学宇宙地球環境研究所, Principal investigator, Competitive research funding
• グリーンランドにおけるグラファイト層の総合研究:38億年前の生物活動と生息環境
  科学研究費助成事業
  Apr. 2006 - Mar. 2008
  大友 陽子
  イスア地域の黒色頁岩及び縞状鉄鉱層に関する研究成果を以下に示す。
  (1)黒色頁岩において、グラファイト含有量<8.8wt%、炭素安定同位体値が-20‰前後の露頭では主要鉱物が緑泥石なのに対し、グラファイト含有量<0.5wt%、炭素安定同位体値が〜-14‰の露頭では角閃石・石英である。これは、Fe(III)を含む緑泥石がグラファイトを酸化して、二酸化炭素と角閃石(Fe(II))に置き換わる反応が起こったと考えられる。このように、同一層であっても、局所的にグラファイトの酸化が起こっている証拠が見つかった。
  (2)希土類元素含有量測定から、グラファイトの含有量が少ない露頭はLight-REEに欠乏したパターンを示すことが解った。これは、変成作用中に、REEを多量に含む鉱物が変成流体に溶して、岩石中から取り去られたものと考えられる。この結果はグラファイト含有量や炭素同位体値の結果とも調和的である。
  以上より、地質学的・地球化学的・岩石鉱物学的データをすべて対比させることが出来た。このように詳細なデータはこれまでの研究にないものであり、本研究結果から最古のグラファイトの起源のみならず、変成中のグラファイト-流体の同位体交換や移動プロセスについても言及することが可能となった。
  (3)縞状鉄鉱層中の角閃石の化学組成を測定した。北部の低変成地域ではマグネシウムに富むカミングトナイト、アンソフィライトのみが観察されるのに対し、南部の高変成地域は鉄に富むグリューネライトに卓越している。このことから、南部の縞状鉄鉱層堆積時にはシデライトが沈殿しており、変成作用の際の二次反応でグリューネライトが出来たと考えられる。
  これにより、詳細な岩石鉱物学的記載から、これまで行われていなかった初生鉱物の推定が可能になった。
  日本学術振興会, 特別研究員奨励費, 東北大学, 06J05251

• Ancient graphene formed 3 billion years before humans discovered it
  Jul. 2023
  Other than myself
  New Scientist
  New Scientist
  https://www.newscientist.com/article/2382891-ancient-graphene-formed-3-billion-years-before-humans-discovered-it/, [Internet]
• 第27回山下太郎学術研究奨励賞受賞.
  May 2016
  秋田魁新報
• 世界最古の生命跡発見・東北大などグリーンランドで
  Dec. 2013
  読売新聞
• 38億年前地球最古の生命
  Dec. 2013
  河北新報
• 38億年前の生物、グリーンランドで痕跡 東北大など
  Dec. 2013
  日本経済新聞電子版