Details of the Researcher

PHOTO

Ryuji Asami
Section
Graduate School of Science
Job title
Associate Professor
Degree

  • 博士（理学）（東北大学）

  • 修士（理学）（東北大学）

Research History 6

  • 2017/10 - Present
    Tohoku University　Graduate School of Science, Department of Earth Science

  • 2014/05 - 2017/09
    University of the Ryukyus　Faculty of Science

  • 2013/04 - 2014/04
    University of the Ryukyus　Faculty of Science

  • 2009/01 - 2013/03
    University of the Ryukyus　Transdisciplinary Research Organization for Subtropics and Island Studies (TRO-SIS)

  • 2006/04 - 2008/12
    Tohoku University　Graduate School of Science, Department of Earth Science

  • 2004/10 - 2006/03
    Tohoku University　Graduate School of Science, Department of Earth Science

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Committee Memberships 3

  • Asia Oceania Geoscience Society　Editorial Board of Geoscience Letters

    2023/01 - Present

  • 日本地質学会　代議員

    2018 - 2019

  • 日本地質学会　代議員

    2014 - 2015

Professional Memberships 11

  • プラズマ分光分析研究会

  • Paleosciences Society

  • American Geophysical Union

  • THE SEDIMENTOLOGICAL SOCIETY OF JAPAN

  • JAPAN GEOSCIENCE UNION

  • JAPANESE CORAL REEF SOCIETY

  • THE OCEANOGRAPHIC SOCIETY OF JAPAN

  • JAPAN ASSOCIATION FOR QUATERNARY RESEARCH

  • PALAEONTOLOGICAL SOCIETY OF JAPAN

  • THE GEOCHEMICAL SOCIETY OF JAPAN

  • THE GEOLOGICAL SOCIETY OF JAPAN

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Research Interests 4

  • 古環境学

  • 環境解析

  • 古気候学

  • 炭酸塩地球化学

Research Areas 2

  • Environmental science/Agricultural science / Environmental dynamics /

  • Natural sciences / Biogeoscience /

Awards 6

  1. 若手優秀発表賞

    2023/11　日本サンゴ礁学会　与論島の土地利用変遷によるサンゴ礁環境の経年変動：現生サンゴ骨格の年輪解析からの復元

  2. Best Presentation Award

    2017/05　Japan Geoscience Union

  3. 日本地質学会 優秀ポスター賞

    2016/09　日本地質学会

  4. 日本古生物学会例会 優秀講演賞

    2015/01　日本古生物学会

  5. 日本地質学会 優秀講演賞

    2005/09　日本地質学会

  6. 21世紀COE北方圏気候変動に関する国際レビュー会議 最優秀ポスター賞

    2004/03　東北大学

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Papers 85

  1. Initiation and internal structure of temperate coral reef community over the past 7.3 kyr in Kushimoto, mainland of Japan Peer-reviewed

    Chuki Hongo, Ryuji Asami, Hiroya Yamano

    Marine Geology　481　107499-107499　2025/03

    Publisher: Elsevier BV

    DOI： 10.1016/j.margeo.2025.107499 　

    ISSN： 0025-3227

  2. Expedition 389 summary

    J.M. Webster, A.C. Ravelo, H.L.J. Grant, M. Rydzy, M. Stewart, N. Allison, R. Asami, B. Boston, J.C. Braga, L. Brenner, X. Chen, P. Chutcharavan, A. Dutton, T. Felis, N. Fukuyo, E. Gischler, S. Greve, A. Hagen, Y. Hamon, E. Hathorne, M. Humblet, S. Jorry, P. Khanna, E. Le Ber, H. McGregor, R. Mortlock, T. Nohl, D. Potts, A. Prohaska, N. Prouty, W. Renema, K.H. Rubin, H. Westphal, Y. Yokoyama

    Proceedings of the International Ocean Discovery Program　2025/02/26

    Publisher: International Ocean Discovery Program

    DOI： 10.14379/iodp.proc.389.101.2025 　

    eISSN： 2377-3189

  3. Multidecadal hydroclimate responses to volcanic forcing in the Mid-Holocene Peer-reviewed

    Syed Azharuddin, Kanako Omine, Kosuke Masaka, Ryuji Asami, Mahjoor Ahmad Lone, Yu-Chen Chou, Chuan-Chou Shen, Ryu Uemura

    Communications Earth & Environment　6　(1)　2025/02

    Publisher: Springer Science and Business Media LLC

    DOI： 10.1038/s43247-025-02047-0 　

    eISSN： 2662-4435

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    Abstract The impact of volcanic and solar forcings on multi-decadal climate change during the Holocene remains unclear. Here, we analysed the stable isotopes of fluid inclusions in a stalagmite to investigate hydroclimate responses to the forcings in the Northwest Pacific region. Our stalagmite data, covering the active volcanism period in the mid-Holocene, showed that the start of large volcanic eruption clusters tends to coincide with an onset or an ongoing cooling phase. The impact of one of the largest volcanic eruptions during the Holocene, likely at Kikai caldera, is recorded as an amplified multi-decadal scale variation, including a noticeable cold-wet climate anomaly. Excluding this anomalous period, the solar forcing record negatively correlated with stalagmite-derived precipitation but not with stalagmite-derived temperature. Our data suggest that clusters of volcanic activity during the mid-Holocene likely contribute to climate change at multi-decadal scale via a teleconnection between the Northwest Pacific and the North Atlantic regions.

  4. 最終氷期の沖縄はどのくらい寒かったのか？-石筍と遺跡貝化石による地質考古学的手法からの復元-

    浅海竜司

    九州旧石器（Palaeolithic Kyusyu）　28　201-209　2024/11

  5. Tropical coral records of monthly ocean-temperature changes during the last deglaciation from IODP drilling

    Past Global Changes Magazine　32　(2)　78-79　2024/10

    Publisher: Past Global Changes (PAGES)

    DOI： 10.22498/pages.32.2.78 　

    ISSN： 2411-605X

    eISSN： 2411-9180

  6. 生物礁 いろいろな時代，さまざまな生物 Peer-reviewed

    井龍康文, 足立奈津子, 山本和幸, 藤田和彦, 浅海竜司, 山野博哉, 高柳栄子

    日本サンゴ礁学会誌　2024/08

    DOI： 10.3755/jcrs.26.59 　

  7. Expedition 389 Preliminary Report: Hawaiian Drowned Reefs

    Webster, J.M., Ravelo, A.C., Grant, H.L.J., he Expeditio, Scientists

    International Ocean Discovery Program Preliminary Report　2024/05

    Publisher: International Ocean Discovery Program

    DOI： 10.14379/iodp.pr.389.2024 　

    ISSN： 2372-9562

  8. IODP Expedition 389 航海報告 : Hawaiian Drowned Reefs”ハワイの海底下に眠るサンゴ礁を掘削!!過去4回の氷期・間氷期サイクルを知る鍵となるか!?”

    浅海竜司, 福與直人, Marc HUMBLET, 横山祐典

    J-DESC Newsletter　17　21-23　2024/05

  9. Paleoenvironmental significance of growth story of long-living deep-water acervulinid macroids from Kikai-jima shelf, Central Ryukyu Islands, Japan Peer-reviewed

    Davide Bassi, Juan Carlos Braga, Ryuji Asami, Kazuhisa Goto, Sönke Szidat, Hideko Takayanagi, Yasufumi Iryu

    Palaeogeography, Palaeoclimatology, Palaeoecology　112254-112254　2024/05

    Publisher: Elsevier BV

    DOI： 10.1016/j.palaeo.2024.112254 　

    ISSN： 0031-0182

  10. Last Deglacial Environmental Change in the Tropical South Pacific From Tahiti Corals Peer-reviewed

    Oliver Knebel, Thomas Felis, Ryuji Asami, Pierre Deschamps, Martin Kölling, Denis Scholz

    Paleoceanography and Paleoclimatology　39　(2)　2024/02/19

    Publisher: American Geophysical Union (AGU)

    DOI： 10.1029/2022pa004585 　

    ISSN： 2572-4517

    eISSN： 2572-4525

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    Abstract On glacial‐interglacial time scales, changes in the Earth's orbital configuration control climate seasonality and mean conditions. Tropical coral skeletons can be sampled at a sufficient resolution to reconstruct past seasonality. Here, last deglacial Porites skeletons from Integrated Ocean Drilling Program Expedition 310 to Tahiti are investigated and, supported by a modern calibration, monthly resolved time series in geochemical proxies (Sr/Ca, δ18O, δ13C) are constructed. For most of the deglaciation, Sr/Ca seasonality was similar to modern (0.139 ± 0.010 mmol mol−1; 2.8 ± 0.2°C) reflecting the small change in insolation seasonality. However, during the Younger Dryas, high values in Sr/Ca seasonality (0.171 ± 0.017 mmol mol−1; 3.4 ± 0.3°C) suggest a reduced mixed layer depth and enhanced influence of the South Pacific Subtropical Gyre due to South Pacific Convergence Zone (SPCZ) inactivity. Furthermore, high amplitudes in Younger Dryas skeletal δ18O (0.40 ± 0.22 ‰) and δ13C (0.86 ± 0.22 ‰) seasonality compared to modern (δ18O = 0.29 ± 0.08 ‰; δ13C = 0.27 ± 0.08 ‰) point to elevated winter‐summer discrepancies in rainfall and runoff. Mean coral Sr/Ca variability suggests an influence of Northern Hemisphere climate events, such as the Younger Dryas cooling (+0.134 ± 0.012 mmol mol−1;−2.6 ± 0.2°C), or the Bølling–Allerød warming (+0.032 ± 0.040 mmol mol−1; −0.6 ± 0.4°C). Deglacial mean coral Δδ18O (δ18Oseawater contribution to skeletal δ18O), corrected for the ice volume effect, was elevated pointing to more saline, thus dryer conditions, likely due to a northward migration of the SPCZ. Seasonal cycles in coral δ13C were likely caused by variations in linear extension rates that were reduced during the last deglaciation (1.00 ± 0.6 cm year−1) compared to today (1.6 ± 0.3 cm year−1).

  11. Multidecadal-to-interannual modulations of Late Holocene climate variations reconstructed from oxygen isotope ratios of a 237-year-long lived fossil coral in Kikai Island, southwestern Japan International-journal Peer-reviewed

    Ko-Yuan Chuang, Ryuji Asami, Hideko Takayanagi, Maki Morimoto, Osamu Abe, Toru Nakamori, Yasufumi Iryu

    Quaternary Science Reviews　322　(108392)　2023/11/11

    Publisher: Elsevier

    DOI： 10.1016/j.quascirev.2023.108392 　

  12. Are the coral mounds of the Kushimoto area, Wakayama Prefecture, Japan, submerged Holocene reefs? Peer-reviewed

    Chuki Hongo, Ryuji Asami, Yasufumi Iryu

    Galaxea, Journal of Coral Reef Studies　26　1-7　2023/03/30

    DOI： 10.3755/galaxea.G26-1 　

  13. Last glacial temperature reconstructions using coupled isotopic analyses of fossil snails and stalagmites from archaeological caves in Okinawa, Japan International-journal Peer-reviewed

    Ryuji Asami, Rikuto Hondo, Ryu Uemura, Masaki Fujita, Shinji Yamasaki, Chuan-Chou Shen, Chung-Che Wu, Xiuyang Jiang, Hideko Takayanagi, Ryuichi Shinjo, Akihiro Kano, Yasufumi Iryu

    Scientific Reports　11　(1)　21922-21922　2021/11

    Publisher: Springer Science and Business Media LLC

    DOI： 10.1038/s41598-021-01484-z 　

    eISSN： 2045-2322

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    <title>Abstract</title>We applied a new geoarchaeological method with two carbonate archives, which are fossil snails from Sakitari Cave and stalagmites from Gyokusen Cave, on Okinawa Island, Japan, to reconstruct surface air temperature changes over the northwestern Pacific since the last glacial period. Oxygen isotope ratios (δ18O) of modern and fossil freshwater snail shells were determined to infer seasonal temperature variations. The observational and analytical data confirm that δ18O values of fluid inclusion waters in the stalagmite can be regarded as those of spring waters at the sites where snails lived. Our results indicate that the annual mean, summer, and winter air temperatures were lower by 6–7 °C at ca. 23 thousand years ago (ka) and 4–5 °C at ca. 16–13 ka than those of the present day. Our reconstruction implies that surface air cooling was possibly two times greater than that of seawater around the Ryukyu Islands during the Last Glacial Maximum, which potentially enhanced the development of the East Asian summer monsoon during the last deglaciation. Considering the potential uncertainties in the temperature estimations, the climatic interpretations of this study are not necessarily definitive due to the limited number of samples. Nevertheless, our new geoarchaeological approach using coupled δ18O determinations of fossil snails and stalagmite fluid inclusion waters will be useful for reconstructing snapshots of seasonally resolved time series of air temperatures during the Quaternary.

  14. Reconstruction of ocean environment time series since the late nineteenth century using sclerosponge geochemistry in the northwestern subtropical Pacific Peer-reviewed

    Ryuji Asami, Taketo Matsumori, Ryuichi Shinjo, Ryu Uemura, Yuki Miyaoka, Masaru Mizuyama, Yuji Ise, Takashi Sakamaki

    Progress in Earth and Planetary Science　8　(38)　2021/06

    DOI： 10.1186/s40645-021-00434-7 　

    ISSN： 2197-4284

    eISSN： 2197-4284

  15. High‐Resolution Evidence for Middle Holocene East Asian Winter and Summer Monsoon Variations: Snapshots of Fossil Coral Records Peer-reviewed

    Ryuji Asami, Natsumi Yoshimura, Hiroto Toriyabe, Shogo Minei, Ryuichi Shinjo, Chuki Hongo, Takashi Sakamaki, Kazuhiko Fujita

    Geophysical Research Letters　47　(16)　2020/08/28

    Publisher: American Geophysical Union (AGU)

    DOI： 10.1029/2020gl088509 　

    ISSN： 0094-8276

    eISSN： 1944-8007

  16. Evaluation of geochemical records as a paleoenvironmental proxy in the hypercalcified demosponge Astrosclera willeyana Peer-reviewed

    Ryuji Asami, Akira Kinjo, Daiki Ohshiro, Tohru Naruse, Masaru Mizuyama, Ryu Uemura, Ryuichi Shinjo, Yuji Ise, Yoshihisa Fujita, Takashi Sakamaki

    Progress in Earth and Planetary Science　7　(15)　2020/05

    DOI： 10.1186/s40645-020-00329-z 　

    ISSN： 2197-4284

    eISSN： 2197-4284

  17. Bomb-produced radiocarbon in the western tropical Pacific Ocean: Guam coral reveals operation-specific signals from the Pacific Proving Grounds Peer-reviewed

    Allen H. Andrews, Ryuji Asami, Yasufumi Iryu, Donald R. Kobayashi, Frank Camacho

    JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS　121　(8)　6351-6366　2016/08

    DOI： 10.1002/2016JC012043 　

    ISSN： 2169-9275

    eISSN： 2169-9291

  18. Precise oxygen and hydrogen isotope determination in nanoliter quantities of speleothem inclusion water by cavity ring-down spectroscopic techniques Peer-reviewed

    Ryu Uemura, Masashi Nakamoto, Ryuji Asami, Satoru Mishima, Masakazu Gibo, Kosuke Masaka, Chen Jin-Ping, Chung-Che Wu, Yu-Wei Chang, Chuan-Chou Shen

    GEOCHIMICA ET COSMOCHIMICA ACTA　172　159-176　2016/01

    DOI： 10.1016/j.gca.2015.09.017 　

    ISSN： 0016-7037

    eISSN： 1872-9533

  19. Response of Acropora digitifera to ocean acidification: constraints from δ11B, Sr, Mg, and Ba compositions of aragonitic skeletons cultured under variable seawater pH Peer-reviewed

    Kentaro Tanaka, Michael Holcomb, Asami Takahashi, Haruko Kurihara, Ryuji Asami, Ryuichi Shinjo, Kohki Sowa, Kai Rankenburg, Tsuyoshi Watanabe, Malcolm McCulloch

    Coral Reefs　34　(4)　1139-1149　2015/12/01

    Publisher: Springer Verlag

    DOI： 10.1007/s00338-015-1319-6 　

    ISSN： 0722-4028

    eISSN： 1432-0975

  20. Late Holocene coral reef environment recorded in Tridacnidae shells from archaeological sites in Okinawa-jima, subtropical southwestern Japan Peer-reviewed

    Ryuji Asami, Mika Konishi, Kentaro Tanaka, Ryu Uemura, Masahide Furukawa, Ryuichi Shinjo

    ISLAND ARC　24　(1)　61-72　2015/03

    DOI： 10.1111/iar.12076 　

    ISSN： 1038-4871

    eISSN： 1440-1738

  21. Selected scientific results of the Integrated Ocean Drilling Program Expedition 310 "Tahiti Sea Level"

    井龍康文, 浅海竜司

    月刊地球　(64)　81-87　2014

    Publisher:

    ISSN： 0916-9733

  22. MIS 7 interglacial sea-surface temperature and salinity reconstructions from a southwestern subtropical Pacific coral Peer-reviewed

    Ryuji Asami, Yasufumi Iryu, Kimio Hanawa, Takashi Miwa, Peter Holden, Ryuichi Shinjo, Gustav Paulay

    Quaternary Research (United States)　80　(3)　575-585　2013/11

    DOI： 10.1016/j.yqres.2013.09.002 　

    ISSN： 0033-5894 1096-0287

  23. Interlaboratory study for coral Sr/Ca and other element/Ca ratio measurements Peer-reviewed

    Ed C. Hathorne, Alex Gagnon, Thomas Felis, Jess Adkins, Ryuji Asami, Wim Boer, Nicolas Caillon, David Case, Kim M. Cobb, Eric Douville, Peter deMenocal, Anton Eisenhauer, Dieter Garbe-Schoenberg, Walter Geibert, Steven Goldstein, Konrad Hughen, Mayuri Inoue, Hodaka Kawahata, Martin Koelling, Florence L. Cornec, Braddock K. Linsley, Helen V. McGregor, Paolo Montagna, Intan S. Nurhati, Terrence M. Quinn, Jacek Raddatz, Helene Rebaubier, Laura F. Robinson, Aleksey Sadekov, Rob Sherrell, Dan Sinclair, Alexander W. Tudhope, Gangjian Wei, Henri Wong, Henry C. Wu, Chen-Feng You

    GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS　14　(9)　3730-3750　2013/09

    DOI： 10.1002/ggge.20230 　

    ISSN： 1525-2027

    eISSN： 1525-2027

  24. Ocean acidification trend in the tropical North Pacific since the mid-20th century reconstructed from a coral archive Peer-reviewed

    Ryuichi Shinjo, Ryuji Asami, Kuo-Fang Huang, Chen-Feng You, Yasufumi Iryu

    MARINE GEOLOGY　342　58-64　2013/08

    DOI： 10.1016/j.margeo.2013.06.002 　

    ISSN： 0025-3227

    eISSN： 1872-6151

  25. Pronounced interannual variability in tropical South Pacific temperatures during Heinrich Stadial 1 International-journal Peer-reviewed

    Thomas Felis, Ute Merkel, Ryuji Asami, Pierre Deschamps, Ed C. Hathorne, Martin Koelling, Edouard Bard, Guy Cabioch, Nicolas Durand, Matthias Prange, Michael Schulz, Sri Yudawati Cahyarini, Miriam Pfeiffer

    NATURE COMMUNICATIONS　3　965-965　2012/07

    DOI： 10.1038/ncomms1973 　

    ISSN： 2041-1723

  26. Seawater temperature proxies based on D-Sr, D-Mg, and D-U from culture experiments using the branching coral Porites cylindrica Peer-reviewed

    Armid, Alrum, Asami, Ryuji, Fahmiati, Tanri, Sheikh, Mohammed Ali, Fujimura, Hiroyuki, Higuchi, Tomihiko, Taira, Eiko, Shinjo, Ryuichi, Oomori, Tamotsu

    GEOCHIMICA ET COSMOCHIMICA ACTA　75　(15)　4273-4285　2011/08

    DOI： 10.1016/j.gca.2011.05.010 　

    ISSN： 0016-7037

  27. Sources of plutonium to the tropical Northwest Pacific Ocean (1943-1999) identified using a natural coral archive Peer-reviewed

    Patric Lindahl, Ryuji Asami, Yasufumi Iryu, Paul Worsfold, Miranda Keith-Roach, Min-Seok Choi

    GEOCHIMICA ET COSMOCHIMICA ACTA　75　(5)　1346-1356　2011/03

    DOI： 10.1016/j.gca.2010.12.012 　

    ISSN： 0016-7037

    eISSN： 1872-9533

  28. Evidence for tropical South Pacific climate change during the Younger Dryas and the Bolling-Allerod from geochemical records of fossil Tahiti corals Peer-reviewed

    Ryuji Asami, Thomas Felis, Pierre Deschamps, Kimio Hanawa, Yasufumi Iryu, Edouard Bard, Nicolas Durand, Masafumi Murayama

    EARTH AND PLANETARY SCIENCE LETTERS　288　(1-2)　96-107　2009/10

    DOI： 10.1016/j.epsl.2009.09.011 　

    ISSN： 0012-821X

    eISSN： 1385-013X

  29. A review of paleoenvironmental studies on Sr/Ca ratios and oxygen isotopes from fossil corals Peer-reviewed

    ASAMI Ryuji

    Fossils　86　67-78　2009

  30. Climatic and oceanographic records from modern coral skeletons for the last several centuries: Reconstruction of interannual, decadal-multidecadal, and centennial variability. Peer-reviewed

    Asami, R, Yamada, T, Iryu, Y

    Chikyukagaku (Geochemistry)　40　(3)　179-194　2006/09

    Publisher: The Geochemical Society of Japan

    DOI： 10.14934/chikyukagaku.40.179 　

    ISSN： 0386-4073

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    Massive hermatypic corals are one of the most excellent archives for reconstructing paleoclimatic and paleoceanographic changes because they commonly live in shallow tropical and subtropical oceans, grow at a rapid rate, and contain a remarkable array of geochemical tracers within their skeletons. In particular, oxygen isotopic composition and Sr/Ca ratio of coral skeletons have been used as proxies for past thermal and hydrological variations in sea surface conditions. Recent investigations on geochemical records of modern long coral cores provide continuous time series of sea surface temperature and salinity in many tropical regions, which document climatic variability on interannual and decadal to multidecadal timescales (El Nino/ Southern Oscillation, Indian Ocean Dipole mode, and Inter-decadal Pacific Oscillation), volcanic eruptions, and global warming. However, high-resolution paleoclimatic records of coral skeletons over the last several centuries are spatially limited and the mechanisms causing the climatic variability remain unclear at present. High-fidelity paleoclimatology should be progressed in order to expand our knowledge on the nature and causes of global climatic changes.

  31. Interannual and decadal variability of the western Pacific sea surface condition for the years 1787-2000: Reconstruction based on stable isotope record from a Guam coral Peer-reviewed

    R Asami, T Yamada, Y Iryu, TM Quinn, CP Meyer, G Paulay

    JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS　110　(C5)　1-13　2005/05

    DOI： 10.1029/2004JC002555 　

    ISSN： 0148-0227

  32. Carbon and oxygen isotopic composition of a Guam coral and their relationships to environmental variables in the western Pacific Peer-reviewed

    R Asami, T Yamada, Y Iryu, CP Meyer, TM Quinn, G Paulay

    PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY　212　(1-2)　1-22　2004/09

    DOI： 10.1016/j.palaeo.2004.05.014 　

    ISSN： 0031-0182

  33. A Review of Paleoenvironmental Reconstructions Based on Mg/Ca and Sr/Ca Thermometry in Goral Skeletons Peer-reviewed

    Ryuji Asami, Tsutomu Yamada, Yasufumi Iryu

    The Quat. Res.　43　(3)　231-245　2004

    Publisher: Japan Association for Quaternary Research

    DOI： 10.4116/jaqua.43.231 　

    ISSN： 0418-2642

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    Reconstruction of changes in the tropical ocean-atmosphere system in the period prior to the use of instrumental records requires the use of climatic and oceanographic proxies such as corals and tree rings. The elemental ratios (Mg/Ca and Sr/Ca) in massive coral skeletons have been used to calculate high-resolution (weekly to monthly) SST (sea surface temperature) in tropical and subtropical oceans during the Quaternary period because there exist significant relationships between the ratios and SST. However, some investigations indicate that skeletal Mg/Ca and Sr/Ca may be influenced by seawater Mg2+/Ca2+ and Sr2+/Ca2+ variations, vital effects, heterogeneity effects, submarine and meteoric diagenesis, and various chemical treatments. If these influences are evaluated quantitatively, the Mg/Ca and Sr/Ca thermometers will provide more accurate past SST than at present.

  34. 九州地方の洞窟

    浅海竜司

    日本の洞窟（狩野彰宏・柏木健治編）　171-176　2025/04

  35. 沖縄地方の洞窟

    浅海竜司

    日本の洞窟（狩野彰宏・柏木健治編）　177-184　2025/04

  36. Monthly interpolated geochemical data and linear extension rates from IODP Expedition 310 Tahiti corals

    Oliver Knebel, Thomas Felis, Ryuji ASAMI, Pierre Deschamps, Martin Kölling, Denis Scholz

    PANGAEA　https://doi.pangaea.de/10.1594/PANGAEA.955157　2024/02

  37. Monthly interpolated geochemical data and linear extension rates from modern Tahiti corals

    Oliver Knebel, Thomas Felis, Ryuji ASAMI, Pierre Deschamps, Martin Kölling, Denis Scholz

    PANGAEA　https://doi.pangaea.de/10.1594/PANGAEA.955127　2024

  38. 動的時間伸縮法によるサンゴ年輪データの時系列変換

    阿部理, 浅海竜司, 奥平早香, 森本真紀

    岐阜大学教育学部研究報告　47　41-46　2023/03

  39. Quantitative reconstruction of air-temperature in Okinawa during the last deglaciation by fluid inclusions analyses of a stalagmite

    Uemura Ryu, Mishima Satoru, Nakamura Koki, Asami Ryuji, Kato Hirokazu, Kano Akihiro, Chen Jin―Ping, Shen Chuan―Chou

    Abstracts of Annual Meeting of the Geochemical Society of Japan　68　55　2021

    Publisher: GEOCHEMICAL SOCIETY OF JAPAN

    DOI： 10.14862/geochemproc.68.0_55 　

  40. Oxygen isotope record during GI-21 from a stalagmite in Minami-daito island, Okinawa

    Uemura Ryu, Asami Ryuji, Abe Osamu, YUAN Shufang, WANG Xianfeng

    Abstracts of Annual Meeting of the Geochemical Society of Japan　67　72　2020

    Publisher: GEOCHEMICAL SOCIETY OF JAPAN

    DOI： 10.14862/geochemproc.67.0_72 　

  41. Carbon and oxygen isotope records of Tridacna squamosa shells from two different latitudes in the Ryukyu Islands Peer-reviewed

    Kodama, S, Takanayagi, H, Yoshii, K., Ha, T. T. N., Asami, R., Abe, O., Iryu, Y.

    Paleontological Research　25　(2)　2020

    Publisher: The Paleontological Society of Japan

    DOI： 10.2517/2020PR003 　

    ISSN： 1342-8144

  42. Preliminary Test of the EA-AGE3 System for 14C Measurement of CaCO3 Samples and Coral-Based Estimation of Marine Reservoir Correction in the Ogasawara Islands, Northwestern Subtropical Pacific Peer-reviewed

    Yoko Saito-Kokubu, Takehiro Mitsuguchi, Takahiro Watanabe, Tsutomu Yamada, Ryuji Asami, Yasufumi Iryu

    Radiocarbon　61　(5)　1593-1601　2019/10

    Publisher: Cambridge University Press (CUP)

    DOI： 10.1017/rdc.2019.69 　

    ISSN： 0033-8222

    eISSN： 1945-5755

    More details Close

    <title>ABSTRACT</title>We conducted a preliminary test of the coupled system of an elemental analyzer and the automated graphitization equipment Ionplus AGE3 (EA-AGE3 method) for accelerator mass spectrometry radiocarbon (AMS 14C) measurements of CaCO3 samples, by comparing with the conventional method where the samples are hydrolyzed in phosphoric acid and resulting CO2 gas is manually graphitized in a vacuum line (HPA method). The samples used in the test were the IAEA C2 travertine, fossil and modern corals from the Ryukyu Islands and the Ogasawara Islands, respectively (both are located in the northwestern subtropical Pacific). Results indicate that, relative to the HPA method, the EA-AGE3 method tends to cause an increase of ~0.4–0.5 pMC with more widely scattered data. This is presumably due to 14C contamination in the EA (the most likely cause seems to be a memory effect of 14C); this effect could be reduced by careful optimization of conditions and procedures in the EA process. The 14C data of pre-bomb annual bands (1931–1949 AD) in the modern Ogasawara coral obtained by the HPA method were used to estimate the marine reservoir 14C-age correction (ΔR) of this region; it ranges from –109 yr to –28 yr with the mean value with standard deviation of –81 ± 29 yr.

  43. 1400-year oxygen and carbon isotopic records from a stalagmite in Minami-daito island, Japan

    Uemura Ryu, Asami Ryuji, Ahmad LONE Mahjoor, CHOU Yu―Chen, SHEN Chuan―Chou

    Abstracts of Annual Meeting of the Geochemical Society of Japan　66　65　2019

    Publisher: GEOCHEMICAL SOCIETY OF JAPAN

    DOI： 10.14862/geochemproc.66.0_65 　

  44. Production age, transport and depositional processes of beach sediments around Sesoko Island (Okinawa, Japan), based on abrasion grades and radiocarbon ages of empty tests of Baculogypsina sphaerulata (Foraminifera) Peer-reviewed

    Mayuko Ito, Ai Mori, Chuki Hongo, Ryuji Asami, Yosuke Miyairi, Yusuke Yokoyama, Kazuhiko Fujita

    J. Jap. Coral Reef Soc　20　(1)　1-20　2018

  45. Nonlinear relationship between preservation of microstructure and geochemical composition of Pleistocene brachiopod shells from the Ryukyu Islands, southwestern Japan Peer-reviewed

    Kazuyuki Yamamoto, Mamoru Takizawa, Hideko Takayanagi, Ryuji Asami, Yasufumi Iryu

    ISLAND ARC　26　(6)　2017/11

    DOI： 10.1111/iar.12217 　

    ISSN： 1038-4871

    eISSN： 1440-1738

  46. Recent Dasycladales (Chlorophyta) in Okinawa Jima in the Central Ryukyus, southwestern Japan: Paleontological implications Peer-reviewed

    Hideo Ohba, Shinya Matsuda, Ryuji Asami, Yasufumi Iryu

    ISLAND ARC　26　(3)　2017/05

    DOI： 10.1111/iar.12185 　

    ISSN： 1038-4871

    eISSN： 1440-1738

  47. The climate changes in a mid-Holocene stalagmite from Minami Daito, Okinawa

    Omine Kanako, Uemura Ryu, Masaka Kosuke, Asami Ryuji, Shen Chuan―Chou

    Abstracts of Annual Meeting of the Geochemical Society of Japan　64　96-96　2017

    Publisher: GEOCHEMICAL SOCIETY OF JAPAN

    DOI： 10.14862/geochemproc.64.0_96 　

    More details Close

    <p></p>

  48. Carbon and Oxygen Isotope Records from Tridacna derasa Shells: Toward Establishing a Reliable Proxy for Sea Surface Environments International-journal Peer-reviewed

    Junpei Yamanashi, Hideko Takayanagi, Ayaka Isaji, Ryuji Asami, Yasufumi Iryu

    PLOS ONE　11　(6)　e0157659　2016/06

    DOI： 10.1371/journal.pone.0157659 　

    ISSN： 1932-6203

  49. The climate reconstruction of the Hoshino Cave, Okinawa by isotope analysis of carbonate and fluid inclusion in mid-Holocene stalagmite

    Omine Kanako, Uemura Ryu, Masaka Kosuke, Asami Ryuji, Shen Chuan―Chou, Ahmad Lone Mahjoor

    Abstracts of Annual Meeting of the Geochemical Society of Japan　63　54-54　2016

    Publisher: GEOCHEMICAL SOCIETY OF JAPAN

    DOI： 10.14862/geochemproc.63.0_54 　

    More details Close

    <p></p>

  50. 沖縄島西海岸における中深度サンゴ礁生態系に関する研究

    水山克, 大原拓, 大原拓, WEINSTEIN David, 藤井琢磨, 藤井琢磨, MCCLELLAND Ty, MONTENEGRO Javier, 式場はるか, 浅海竜司, YANG Sung‐yin, 河村伊織, REIMER James Davis

    沖縄生物学会誌　(54)　54-55　2016

  51. Quantitative analysis of intraspecific variations in the carbon and oxygen isotope compositions of the modern cool-temperate brachiopod Terebratulina crossei Peer-reviewed

    Hideko Takayanagi, Ryuji Asami, Tsuguo Otake, Osamu Abe, Toshihiro Miyajima, Hiroyuki Kitagawa, Yasufumi Iryu

    GEOCHIMICA ET COSMOCHIMICA ACTA　170　301-320　2015/12

    DOI： 10.1016/j.gca.2015.08.006 　

    ISSN： 0016-7037

    eISSN： 1872-9533

  52. Carbonate sedimentation in seagrass beds on Ishigaki-jima, Ryukyu Islands, southwestern Japan Peer-reviewed

    Keita Fujita, Ryuji Asami, Hideko Takayanagi, Yasufumi Iryu

    ISLAND ARC　24　(2)　263-279　2015/06

    DOI： 10.1111/iar.12112 　

    ISSN： 1038-4871

    eISSN： 1440-1738

  53. Effects of causeway construction on environment and biota of subtropical tidal flats in Okinawa, Japan International-journal Peer-reviewed

    James Davis Reimer, Sung-Yin Yang, Kristine N. White, Ryuji Asami, Kazuhiko Fujita, Chuki Hongo, Shingo Ito, Iori Kawamura, Isshu Maeda, Masaru Mizuyama, Masami Obuchi, Takashi Sakamaki, Katsunori Tachihara, Maiko Tamura, Akira Tanahara, Aika Yamaguchi, Holger Jenke-Kodama

    MARINE POLLUTION BULLETIN　94　(1-2)　153-167　2015/05

    DOI： 10.1016/j.marpolbul.2015.02.037 　

    ISSN： 0025-326X

    eISSN： 1879-3363

  54. Buried fossil microatolls off the Kaichu-Doro Causeway, between Okinawa and Henza Islands Peer-reviewed

    Fujita K, Hongo C, Koutoku M, Ito S, Asami R, Reimer JD

    Fauna Ryuykuana　24　13-15　2015

  55. Differences in oxygen and carbon stable isotope ratios between hatchery and wild pink salmon fry Peer-reviewed

    Yasuo Tomida, Toshiya Suzuki, Tsutomu Yamada, Ryuji Asami, Hirofumi Yaegashi, Yasufumi Iryu, Tsuguo Otake

    FISHERIES SCIENCE　80　(2)　273-280　2014/03

    DOI： 10.1007/s12562-014-0699-9 　

    ISSN： 0919-9268

    eISSN： 1444-2906

  56. Oxygen isotope analysis of speleothem water inclusion: glacial temperatures reconstruction

    Uemura Ryu, Nakamoto Masashi, Mishima Satoru, Asami Ryuji, Gibo Masakazu, Masaka Kosuke, Jing-Ping Chen, Wu Chung-Che, Chang Yu-Wei, Shen Chuan-Chou

    Abstracts of Annual Meeting of the Geochemical Society of Japan　61　194-194　2014

    Publisher: GEOCHEMICAL SOCIETY OF JAPAN

    DOI： 10.14862/geochemproc.61.0_194 　

  57. Intraspecific variations in carbon-isotope and oxygen-isotope compositions of a brachiopod Basiliola lucida collected off Okinawa-jima, southwestern Japan Peer-reviewed

    Hideko Takayanagi, Ryuji Asami, Osamu Abe, Toshihiro Miyajima, Hiroyuki Kitagawa, Keiichi Sasaki, Yasufumi Iryu

    GEOCHIMICA ET COSMOCHIMICA ACTA　115　115-136　2013/08

    DOI： 10.1016/j.gca.2013.03.026 　

    ISSN： 0016-7037

  58. Correlative relationships between carbon- and oxygen-isotope records in two cool-temperate brachiopod species off Otsuchi Bay, northeastern Japan Peer-reviewed

    Kazuyuki Yamamoto, Ryuji Asami, Yasufumi Iryu

    PALEONTOLOGICAL RESEARCH　17　(1)　12-26　2013/04

    DOI： 10.2517/1342-8144-17.1.12 　

    ISSN： 1342-8144

  59. 古環境指標としての腕足動物殻の炭素同位体組成

    高柳栄子, 浅海竜司, 井龍康文

    月刊地球　35　(12)　690-696　2013

    Publisher:

    ISSN： 0387-3498

  60. Factors controlling isotopic composition of precipitation on Okinawa Island, Japan: Implications for paleoclimate reconstruction in the East Asian Monsoon region Peer-reviewed

    Ryu Uemura, Nao Yonezawa, Kei Yoshimura, Ryuji Asami, Hisashi Kadena, Keita Yamada, Naohiro Yoshida

    JOURNAL OF HYDROLOGY　475　314-322　2012/12

    DOI： 10.1016/j.jhydrol.2012.10.014 　

    ISSN： 0022-1694

  61. Carbon- and oxygen-isotope compositions of a modern deep-water brachiopod Campagea japonica collected off Aguni-jima, Central Ryukyu Islands, southwestern Japan Peer-reviewed

    Hideko Takayanagi, Ryuji Asami, Osamu Abe, Hiroyuki Kitagawa, Toshihiro Miyajima, Yasufumi Iryu

    GEOCHEMICAL JOURNAL　46　(2)　77-87　2012

    DOI： 10.2343/geochemj.1.0153 　

    ISSN： 0016-7002

    eISSN： 1880-5973

  62. Brachiopod taxa and shell portions reliably recording past ocean environments: Toward establishing a robust paleoceanographic proxy Peer-reviewed

    Kazuyuki Yamamoto, Ryuji Asami, Yasufumi Iryu

    GEOPHYSICAL RESEARCH LETTERS　38　2011/07

    DOI： 10.1029/2011GL047134 　

    ISSN： 0094-8276

  63. 沖縄本島西方の粟国島沖（水深606 m）より採取された現生腕足動物殻の炭素・酸素同位体組成

    高柳栄子, 浅海竜司, 井龍康文

    沖縄周辺海域の海洋地質学的研究 平成22年度研究概要報告書—沖縄島西方沖海域—　55　187-193　2011

  64. Within-shell variations in carbon and oxygen isotope compositions of two modern brachiopods from a subtropical shelf environment off Amami-o-shima, southwestern Japan Peer-reviewed

    Kazuyuki Yamamoto, Ryuji Asami, Yasufumi Iryu

    GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS　11　2010/10

    DOI： 10.1029/2010GC003190 　

    ISSN： 1525-2027

  65. Carbonate diagenesis of the Late Pleistocene limestone of the Faaa M0020A core: IODP Expedition 310, Tahiti Sea Level Change Peer-reviewed

    Kyung Sik Woo, Kyeong Hwan Yoon, Young Joo Lee, Tsutomu Yamada, Ryuji Asami, Yasufumi Iryu

    GEOSCIENCES JOURNAL　14　(2)　225-234　2010/06

    DOI： 10.1007/s12303-010-0021-5 　

    ISSN： 1226-4806

  66. Carbon and oxygen isotopic compositions of modern brachiopod shells from a warm-temperate shelf environment, Sagami Bay, central Japan Peer-reviewed

    Kazuyuki Yamamoto, Ryuji Asami, Yasufumi Iryu

    PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY　291　(3-4)　348-359　2010/05

    DOI： 10.1016/j.palaeo.2010.03.006 　

    ISSN： 0031-0182

    eISSN： 1872-616X

  67. 沖縄本島西方海域より採取した底層水の炭素・酸素同位体組成

    高柳栄子, 阿部 理, 浅海竜司, 井龍康文

    沖縄周辺海域の海洋地質学的研究 平成21年度研究概要報告書—沖縄島西方沖海域—　51　86-92　2010

  68. Isotopic and chemical composition of meteoric water, seawater and interstitial water at Tahiti

    Yamada Tsutomu, Kolling Martin, Matsuda Hiroki, Asami Ryuji, Aizawa Shoichi

    Annual Meeting of the Geological Society of Japan　2008　178-178　2008

    Publisher: The Geological Society of Japan

    DOI： 10.14863/geosocabst.2008.0.178.0 　

    ISSN： 1348-3935

  69. 腕足動物殻の炭素・酸素同位体比記録が意味するもの―Kikaithyris hanzawaiおよびBasiliola lucidaを例にして―

    山本和幸, 浅海竜司, 井龍康文

    月刊地球　(59)　86-94　2008

    Publisher:

    ISSN： 0916-9733

  70. IODP Expedition 310 reconstructs sea level, climatic, and environmental changes in the South Pacific during the last deglaciation Peer-reviewed

    Gilbert F. Camoin, Yasufumi Iryu, Dave B. McInroy, R. Asami, H. Braaksma, G. Cabioch, P. Castillo, A. Cohen, J. E. Cole, P. Deschamps, R. G. Fairbanks, T. Felis, K. Fujita, E. Hathorne, S. Lund, H. Machiyama, H. Matsuda, T. M. Quinn, K. Sugihara, A. Thomas, C. Vasconcelos, K. Verwer, R. Warthmann, J. M. Webster, H. Westphal, K. S. Woo, T. Yamada, Y. Yokoyama

    Scientific Drilling　(5)　4-12　2007/09

    DOI： 10.2204/iodp.sd.5.01.2007 　

    ISSN： 1816-8957 1816-3459

  71. P-45 The IODP Expedition 310 'Tahiti Sea Level' : Sea-level changes and reef development during the Last Deglaciation

    Asami R., Iryu Y., Camoin Gilbert, Expedition 310 Scientists

    Annual Meeting of the Geological Society of Japan　2006　190-190　2006

    Publisher: The Geological Society of Japan

    DOI： 10.14863/geosocabst.2006.0_190_2 　

  72. Tahiti Sea Level: the last deglacial sea level rise in the South Pacific: offshore drilling in Tahiti (French Polynesia)

    Expedition, Scientists (Camoin, G. F, Iryu, Y, McInroy, D. B, Asami, R, Braaksma, H, Cabioch, G, Castillo, P, Cohen, A. L, Cole, J. E, Deschamps, P, Fairbanks, R. G, Felis, T, Fujita, K, Hathorne, Ed C, Lund, S. P, Machiyama, H, Matsuda, H, Quinn, T. M, Sugihara, K, Thomas, A, Vasconcelos, C. de O, Verwer, K, Webster, J. M, Westphal, H, Woo, K. S, Yamada, T, Yokoyama, Y

    IODP Preliminary Report, 310　2006

  73. El Nino history over the last 200 years

    Asami Ryuji, Yamada Tsutomu, Iryu Yasufumi

    Annual Meeting of the Geological Society of Japan　2005　240-240　2005

    Publisher: The Geological Society of Japan

    DOI： 10.14863/geosocabst.2005.0_240_2 　

  74. Proceedings of the Ocean Drilling Program, Scientific Results, Volume 182. Peer-reviewed

    Machiyama, H, Yamada, T, Kaneko, N, Iryu, Y, Odawara, K, Asami, R, Matsuda, H, Mawatari, S. F, Bone, Y, James, N. P

    Ocean Drilling Program, Texas A & M University, Texas　1-29　2002/05

  75. O-171 Reliability of paleothermometer and paleosalinometer using coral δ^<18>O and Sr/Ca ratio

    Yamada Tsutomu, Asami Ryuji, Iryu Yasufumi

    Annual Meeting of the Geological Society of Japan　2002　84-84　2002

    Publisher: The Geological Society of Japan

    DOI： 10.14863/geosocabst.2002.0_84_1 　

  76. O-170 Migration and contraction/expansion of WPWP recorded in a Guam coral skeleton

    ASAMI Ryuji, YAMADA Tsutomu, IRYU Yasufumi

    Annual Meeting of the Geological Society of Japan　2002　83-83　2002

    Publisher: The Geological Society of Japan

    DOI： 10.14863/geosocabst.2002.0_83_2 　

  77. P-107 Uncertainty of sea surface temperatures calculated from oxygen isotopic composition in fossil coral skeletons

    KOBAYASHI Hisako, IRYU Yasufumi, YAMADA Tsutomu, ASAMI Ryuji

    Annual Meeting of the Geological Society of Japan　2002　260-260　2002

    Publisher: The Geological Society of Japan

    DOI： 10.14863/geosocabst.2002.0_260_1 　

  78. P-108 Changes in carbon and oxygen isotopic ratios caused by various pre-treatment procedures

    Hemmi Sachi, Yamada Tsutomu, Asami Ryuji

    Annual Meeting of the Geological Society of Japan　2002　260-260　2002

    Publisher: The Geological Society of Japan

    DOI： 10.14863/geosocabst.2002.0_260_2 　

  79. P-109 Sedimentary facies of carbonate deposits in seagrass beds

    FUJITA Keita, IRYU Yasufumi, YAMADA Tsutomu, ASAMI Ryuji

    Annual Meeting of the Geological Society of Japan　2002　261-261　2002

    Publisher: The Geological Society of Japan

    DOI： 10.14863/geosocabst.2002.0_261_1 　

  80. Carbon and oxygen isotopes of cool-water bryozoans from the Great Australian Bight, and their paleoenvironmental significance Peer-reviewed

    Machiyama, H, Yamada, T, Kaneko, N, Iryu, Y, Odawara, K, Asami, R, Matsuda, H, Mawatari, S.F, Bone, Y, James, N.P

    Proc. ODP, Sci. Results, 182, <http://www-odp.tamu.edu/publications/182_SR/007/007.htm>　2002

  81. Holocene SSTs inferred from oxygen isotopic composition of fossil corals.

    Tsutomu Yamada, Hisako Kobayashi, Ryuji Asami, Yasufumi Iryu

    「平成12年度深田研究助成」研究報告　131-144　2001/09/30

  82. O-139 Can bryozoan isotopes be used as a paleoceanographic proxy? : results from the Great Australian Bight, ODP Leg 182

    Machiyama Hideaki, Yamada Tsutomu, Kaneko Naotomo, Iryu Yasufumi, Odawara Kei, Asami Ryuji, Matsuda Hiroki, Mawatari Shunsuke F., Bone Yvonne, James Noel P.

    Annual Meeting of the Geological Society of Japan　2001　70-70　2001

    Publisher: The Geological Society of Japan

    DOI： 10.14863/geosocabst.2001.0_70_2 　

  83. P-98 ENSO episodes recorded in a coral skeleton from Guam

    ASAMI Ryuji, YAMADA Tsutomu, IRYU Yasufumi

    Annual Meeting of the Geological Society of Japan　2001　246-246　2001

    Publisher: The Geological Society of Japan

    DOI： 10.14863/geosocabst.2001.0_246_1 　

  84. コケムシ骨格の同位体比は環境指標として使えるか？－ODP Leg182:グレートオーストラリア湾の測定結果予報－

    町山栄章, 山田 努, 兼子尚知, 井龍康文, 小田原 啓, 浅海竜司, 松田博貴, 馬渡駿輔, Y. Bone・N. P. James

    (53)　117-120　2001

    Publisher:

    ISSN： 1342-310X

  85. P-83 What oceanographic fluctuations are recorded in a Porites skeleton from Guam, western Pacific?

    ASAMI Ryuji, YAMADA Tsutomu, IRYU Yasufumi, NAKAMORI Toru, PAULAY Gustav, MEYER Christopher P.

    Annual Meeting of the Geological Society of Japan　2000　248-248　2000

    Publisher: The Geological Society of Japan

    DOI： 10.14863/geosocabst.2000.0_248_2 　

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Misc. 7

  1. 現生腕足動物殻の微量金属元素濃度に関する基礎的研究

    西尾拓哉, 高柳栄子, 浅海竜司, 新城竜一, 山本鋼志, 井龍康文

    日本古生物学会年会講演予稿集　2018　29　2018/06/22

  2. 腕足動物化石の炭素・酸素同位体組成と殻の微細構造は続成作用の進行によってどのように変化するか

    滝澤護, 佐藤晋佑, TECHAPINYAWAT Lapone, 高柳栄子, CHAROENTITIRAT Thasinee, 浅海竜司, 阿部理, 原英俊, 曽根正敏, 山本鋼志, 井龍康文

    日本地質学会学術大会講演要旨　123rd　293　2016/09/05

    ISSN： 1348-3935

  3. 腕足動物の同位体記録を歪める原因

    高柳栄子, 浅海竜司, 大竹二雄, 阿部理, 宮島利宏, 北川浩之, 井龍康文

    日本古生物学会例会講演予稿集　164th　2015

  4. Within- and inter-shell variations of carbon and oxygen isotope composition in Permian brachiopod shells from the Indochina terrane in Thailand

    Takizawa Mamoru, Iryu Yasufumi, Lapone Techapinawat, Takayanagi Hideko, Charoentitirat Thasinee, Asami Ryuji, Abe Osamu, Hara Hidetoshi, Sone Masatoshi, Yamamoto Koshi

    Annual Meeting of the Geological Society of Japan　2015　(0)　2015

    Publisher: The Geological Society of Japan

    ISSN： 1348-3935

  5. O-93 South Pacific sea surface conditions at 〜200 ka inferred from skeletal records of a fossil Niue coral

    ASAMI Ryuji, YAMADA Tsutomu, IRYU Yasufumi, PAULAY Gustav, MIWA Takashi

    114　107-107　2007/09/01

    Publisher: The Geological Society of Japan

  6. Interannual and decadal variability of sea surace condition recorded in Guam coral for the years 1787-2000

    R Asami, T Yamada, Y Iryu

    GEOCHIMICA ET COSMOCHIMICA ACTA　67　(18)　A27-A27　2003/09

    ISSN： 0016-7037

  7. Precise restoration of the surface sea water temperature for the past 10,000 years based on the skeletal record of the reef-making coral. Restoration of the sea water temperature changes for the past 10,000 years using the coral fossils of the Holocene Ep

    小林久子, 山田努, 浅海竜司, 井龍康文, 大村明雄, 佐々木圭一, 松田伸也, 中森亨

    造礁サンゴの骨格記録に基づく過去1万年間の表面海水温の精密復元 平成12-14年度 No.12304028　13-111　2003

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Books and Other Publications 4

  1. 巨大なサンゴの「年輪から過去の環境を知る」

    ASAMI Ryuji

    ボーダーインク　2015

  2. Large corals can record past climate change

    ASAMI Ryuji

    Faculty of Science, University of the Ryukyus,　2015

  3. Expadition 310: Tahiti Sea Level

    E. C. Hathorne, A. Thomas, IODP Ex, Scientists

    U. K. IODP newsletter　2007

  4. Tahiti Sea Level: the last deglacial sea level rise in the South Pacific: offshore drilling in Tahiti (French Polynesia)

    IODP Expeditio, Scientists

    IODP Preliminary Report　2006

Presentations 13

  1. 炭酸塩試料による過去の大気海洋変動の解析：季節スケールから氷期・間氷期スケールまで Invited

    浅海竜司

    日本地質学会第131回学術大会　2024/09

  2. Last glacial temperature reconstructions using coupled isotopic analyses of fossil snails and stalagmites from archaeological caves in Okinawa, Japan Invited

    Ryuji ASAMI, R. Hondo, R. Uemura, M. Fujita, S. Yamasaki, C.-C. Shen, C.-C. Wu, X. Jiang, H. Takayanagi, R. Shinjo, A. Kano, Y. Iryu

    EGU General Assembly　2022/05

  3. サンゴ骨格を用いた古気候復元 Invited

    浅海竜司

    第65回日本地球化学会年会　2018/09

  4. サンゴ年輪の化学分析による海洋環境復元 Invited

    ASAMI Ryuji

    第102回プラズマ分光分析研究会　2018/03

  5. A stalagmite-inferred high-resolution hydroclimate record at 6-7.5 ka in Okinawa, Japan International-presentation

    Kanako Omine, Ryu Uemura, Kosuke Masaka, Ryuji Asami, Mahjoor Ahmad Lone, Yu-Chen Chou, Chuan-Chou Shen

    American Geophysical Union Fall meeting　2017/12

  6. 沖縄県南大東島の石筍に記録された完新世中期における気候変動

    大嶺佳菜子, 植村立, 眞坂昂佑, 浅海竜司, Chuan-Chou Shen

    地球化学年会　2017/09

  7. Isotopic Compositions of Fluid Inclusions Water from Stalagmites in Okinawa, Japan International-presentation Invited

    R. Uemura, S. Mishima, K. Ohmine, Ryuji ASAMI, C. Jin-Ping, C.-C. Shen

    14th Annual Meeting Asia Oceania Geosciences Society　2017/08

  8. Coral-based climatology: what can we know? International-presentation

    Y. Iryu, H. Takayanagi, Ryuji ASAMI

    International Geoscience Program 630　2017/06

  9. Relationship between climate changes and solar activity in a mid-Holocene stalagmite from Minami Daito, Okinawa

    大嶺佳菜子, 植村立, 眞坂昂佑, 浅海竜司, C.-C. Shen, M. A. Lone

    日本地球惑星科学連合大会　2017/05

  10. Paleoceanographic proxy and skeletal records of sclerosponges from the Ryukyu Islands, Japan International-presentation

    Ryuji ASAMI, T. Matsumori, S. Ishihara, A. Kinjo, D. Ohshiro, T. Naruse, M. Mizuyama, Y. Ise, Y. Fujita, T. Sakamaki

    JpGU-AGU joint Meeting　2017/05

  11. Paleoclimate records in stalagmites from Okinoerabu-jima, Ryukyu Islands, Japan

    浅海竜司, 赤嶺裕二, 源河秀尚, 松本涼太郎, 植村立, 井龍康文, C.-C. Shen

    日本地球惑星科学連合大会　2017/05

  12. 星砂の摩耗度と放射性炭素年代に基づく瀬底島サンゴ礁堆積物の生産・運搬・堆積過程

    伊藤真裕子, 森 愛, 浅海竜司, 本郷宙軌, 宮入陽介, 横山祐典, 藤田和彦

    日本地球惑星科学連合大会　2017/05

  13. 鍾乳石中に流体包有物として保存された過去の水の同位体比分析

    植村立, 仲本壮志, 三嶋悟, 儀保雅一, 浅海竜司, C. Jin-Ping, C.-C. Wu, Y.-W. Chang, C.-C. Shen

    Japan Geoscience Union　2017/05

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Research Projects 17

  1. 不確実性0.5℃以内の古水温復元への挑戦：無機セメントと単体サンゴの直接分析から

    浅海 竜司, 植村 立

    Offer Organization: 日本学術振興会

    System: 科学研究費助成事業

    Category: 挑戦的研究(萌芽)

    Institution: 東北大学

    2024/06 - 2027/03

  2. Adaptive Governance of Multiple Resources based on Land-Sea Linkages of the Water Cycle: Application to Coral Reef Island Systems

    Offer Organization: Research Institute for Humanity and Nature

    System: Research Project

    Institution: Research Institute for Humanity and Nature

    2019/04 - 2027/03

  3. Reconstructions of seawater temperature and salinity time series and the Kuroshio Current variability for the last 400 years using geochemical analyses of large biogenic carbonates

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research

    Category: Grant-in-Aid for Scientific Research (B)

    Institution: Tohoku University

    2022/04/01 - 2026/03/31

  4. 大型海洋生物の化学分析による過去400年の水温・塩分時系列と黒潮変動の解析

    浅海 竜司, 井龍 康文, 阿部 理, 成瀬 貫, 高柳 栄子, 杉本 周作

    Offer Organization: 日本学術振興会

    System: 科学研究費助成事業

    Category: 基盤研究(B)

    Institution: 東北大学

    2022/04/01 - 2026/03/31

  5. 洞窟内での鍾乳石コア掘削による最終氷期以降の日本の気候変動の解明

    植村 立, 阿部 理, 浅海 竜司

    Offer Organization: 日本学術振興会

    System: 科学研究費助成事業 基盤研究(A)

    Category: 基盤研究(A)

    Institution: 名古屋大学

    2020/04 - 2024/03

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    本計画では、主に沖縄地域の洞窟内で鍾乳石を掘削し、鍾乳石コアを採取することで、連続・高時間分解能の環境・気候変動のデータを得る。さらに、鍾乳石内に閉じ込められた流体包有物の同位体比分析をおこなうことで定量的な気候復元を行う。 具体的な研究は以下の２点について実施した。 (1)洞窟内でのボーリングコアを掘削：本年度は、沖縄本島南部の玉泉洞および周辺洞窟において掘削を実施した。今回の掘削の主な目的は古気候復元に適した試料を得られる地点の探索である。新型コロナウィルス感染症対策と緊急事態宣言等によって、掘削の実施は延期されたものの12月に実施することができた。8か所でのコア掘削と数個の石筍採取を行った。多くの掘削地点ではコア掘削作業は順調だったものの、試料の質にはやや問題（密度が低い、多孔質、泥層が含まれる等）が認められた。古気候に非常に適したコア試料はリムストーンを掘削した1試料と破損していた石筍を掘削した1試料の計2試料であった。そのほかの石筍試料も古気候試料として適している。コア試料の切断作業の実施も緊急事態宣言等によって翌年度に遅延したものの実施することができた。これらの掘削の結果をうけて、計画通り来年度も掘削を実施することとし、掘削地は第二候補の洞窟に変更することとした。 (2)同位体・化学分析による気候変動データ 掘削試料が得られるまでの間は、試料の分析に適した各分析システムの改良を進めた。流体包有物の分析システムは、高速処理を目指した改良を随時進めた。水蒸気連続フロー式のシステムを構築し、分析時のメモリー効果が無くすことに成功した。この結果、処理速度は格段に向上した。また、得られた試料の年代をウラン・トリウム法による放射性同位体分析によって実施した。掘削で得られた８試料について、シンガポール南洋工科大学に於いて分析を実施した。

  6. 鍾乳石と貝化石の先端化学分析と文理融合による洞穴遺跡研究の新展開 Competitive

    浅海 竜司

    System: 科学研究費助成事業：挑戦的研究（萌芽）代表

    2018/04 -

  7. In situ boron isotopic analysis of subduction-related volcanic rocks and quantitative evaluation of subduction component

    SHINJO Ryuichi, ASAMI Ryuji, TOKI Tomohiro, ISHIBASHI Jun-ichiro, UNO Yoshie, KINJO Kazuki, YASUDA Keisuke, UZA Hirotaka

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research

    Category: Grant-in-Aid for Scientific Research (C)

    Institution: University of the Ryukyus

    2013/04/01 - 2018/03/31

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    Effective boron separation methods (micro-sublimation and mini-column methods) from geological materials are developed. In addition, laser ablation-multiple-collector ICP mass spectrometer (LA-MC-ICP-MS) method is developed for in situ analyses of boron isotope. Repeated analyses of geological standard reference materials yielded high precision and accurate results. Annual-scale boron isotopic analyses for coral skeleton from Guam Island provide an evidence for ocean acidification in tropic Pacific seawater. Boron isotopic profile analyses for interstitial water in sediments at active hydrothermal area in Okinawa Trough demonstrate that boron isotope is an effective tracer for investigation of sub-bottom circulation pattern of hydrothermal fluids. Boron isotopic analyses by LA-MC-ICP-MS on tourmalines from Yamaguchi Prefecture indicate that fluids related to the formation of tourmaline were strongly linked to host granitic magma.

  8. Long-term chnages in coral-reef ecosystem after historic times, based on sediment cores

    Fujita Kazuhiko, ASAMI Ryuji, YASUMOTO Jun

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research

    Category: Grant-in-Aid for Scientific Research (C)

    Institution: University of the Ryukyus

    2013/04/01 - 2016/03/31

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    Coral reef ecosystems are now being threatened by global environmental changes and human impacts. However, it is still argued that when and how increasing human populations historically affect coral reef ecosystems. We conducted geochemical and micropaleontological analyses of sediment cores drilled from the reclaimed areas of Naha City (Okinawa Prefecture, Japan), where pristine coral reefs had been reclaimed. Results showed that Holocene sediments consisting mainly of bioclastic carbonate sand and mud increasingly contained terrigenous siliciclasts in the upper part of cores, and that some cores potentially record historical changes in terrigenous sediment inputs into coral reef environments, starting from periods of Gusuku and Ryukyu Kingdom.

  9. Reconstruction of past marine environment using coral skeletons collected from Ishigaki Island, southwest of Japan Competitive

    ABE Osamu, IRYU Yasufumi, ASAMI Ryuji, MORIMOTO Maki

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research

    Category: Grant-in-Aid for Scientific Research (B)

    Institution: Nagoya University

    2012/04 - 2016/03/31

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    To reconstruct past marine environments for the last millenium at low-latitude, where paleoenvironmental information is limited, we collected modern and fossil coral skeletons from Ishigaki Island and determined ages, oxygen isotopic composition and minor metal concentrations. We obtained total 1015 years coral records containing the periods of Little Ice Age as well as Medieval Climatic Anomaly.

  10. 鍾乳石の流体包有物同位体分析による第四紀古気候学の新展 Competitive

    System: 科学研究費助成事業：基盤研究（A）分担

    2015/04 -

  11. 琉球列島の石筍の高分解能解析とサンゴデータを組合せた完新世の大気海洋変動復元 Competitive

    浅海 竜司

    System: 科学研究費助成事業：若手研究（A）代表

    2014/04 -

  12. 硬骨海綿の環境解析～複合プロキシによるサンゴ礁海域の時空間変化の復元を目指して～ Competitive

    浅海 竜司

    System: 科学研究費助成事業：挑戦的萌芽研究，代表

    2014/04 -

  13. Reconstruction of long-term oceanic pH variability since the Industrial Revolution from chemical composition in corals around Ryukyu Islands Competitive

    ASAMI Ryuji

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research

    Category: Grant-in-Aid for Young Scientists (B)

    Institution: University of the Ryukyus

    2011/04 - 2013

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    Massive Porites corals from Ryukyu Islands and Guam Island were investigated to analyze long-term trend and variability of ocean environment in the northwestern Pacific Ocean. Analysis of X-ray images showed that the coral cores collected at Okinoerabu-jima, Ryukyu Islands, have continuous annual skeletal density bands for the last 450 years (A.D. 1560-2011). Stable isotope and trace element analyses of the coral skeleton generated high-resolution time series of ocean environment parameters such as seawater temperature, salinity, pH, etc, over the long term. Climate reconstruction using the proxy data suggests that sea surface waters in the tropical and subtropical northwestern Pacific Ocean possibly have become warmer, fresher, and more acid since the mid-20th century.

  14. タイ国産腕足動物化石の炭素・酸素同位体組成を用いた石炭紀～ペルム紀の古環境復元 Competitive

    System: 科学研究費助成事業：基盤研究（B）海外学術調査，分担）

    2012/04 -

  15. タヒチ化石サンゴ骨格記録に基づいた最終氷期最盛期～最終間氷期の古海洋環境復元 Competitive

    浅海 竜司

    Offer Organization: 日本学術振興会

    System: 科学研究費助成事業：特別研究員奨励費

    Category: 特別研究員奨励費

    Institution: 東北大学

    2006/04 - 2008

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    2005年度秋〜冬に施行された,統合国際深海掘削計画の310次航海(Tahiti Sea Level)に参加し,過去のサンゴ礁堆積物から掘削された造礁サンゴ化石の骨格試料を採取した.本研究課題の最も重要な目的の一つは,最終氷期最盛期以降(過去2万年間)に生息したサンゴ化石から古水温ならびに古塩分の時系列データを抽出し,南太平洋熱帯〜亜熱帯域における古海洋環境の変遷(様々なタイムスケールの気候変動現象)を復元することである.そこで,軟X線写真撮影による骨格年輪構造解析,粉末X線回折分析による鉱物組成の同定,走査型電子顕微鏡による骨格構造観察を行い,続成作用の影響を被っていない試料を選別した.そして,それらの炭素・酸素同位体組成ならびに金属元素濃度(Ca,Mg,Sr)の分析を行った.また,現地調査で採取したタヒチ島のサンゴ礁内の海水試料の化学組成分析を行った.サンゴの化学組成の時系列データは1サンプルあたり2週間〜3週間の高時間解像度であり,それらから復元された古水温と古塩分の時系列データには,明瞭な季節変化と数年スケールの変動が認められた.また,複数のサンゴ化石試料の化学分析と統計解析から,最終氷期最盛期以降の海水の温度と酸素同位体組成を復元し,太平洋低〜中緯度域の深海堆積物や極域の氷床コアから得られている古気候データと比較検討を行った.以上の研究成果を,国内(東北大学,名古屋大,高知大学)や海外(Bremen大学,CEREGE)の共同研究者と議論を交わすとともに,国内学会や国際学会で発表した.さらに,原著論文を執筆し,国際学術雑誌に論文を投稿した(Asami et al.,査読中).また,共同研究者と行った研究の成果を原著論文としてまとめ,国際学術雑誌に投稿した(2編,共著,査読中)

  16. タヒチ化石サンゴを用いた過去2万年間の古エルニーニョ記録の復元

    浅海 竜司

    Offer Organization: 日本学術振興会

    System: 科学研究費助成事業

    Category: 若手研究(B)

    Institution: 東北大学

    2006 - 2006

  17. グアム島の造礁サンゴ骨格記録に基づく西太平洋海域の海洋環境変動の復元 Competitive

    浅海 竜司

    Offer Organization: 財団法人藤原ナチュラルヒストリー振興財団

    System: 平成15年度学術研究助成金，代表

    2003/04 -

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