Researcher Profile and Settings

Master

Affiliation (Master)

• Faculty of Environmental Earth Science　Earth System Science　Biogeosystem Science

Affiliation (Master)

• Faculty of Environmental Earth Science　Earth System Science　Biogeosystem Science

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Profile and Settings

Degree

• Ph.D.（The University of Tokyo）

Profile and Settings

• Contact Point

  irinoees.hokudai.ac.jp

• Name (Japanese)

  Irino

• Name (Kana)

  Tomohisa

• Name

  D-9282-2018, 200901072141492364

Alternate Names

https://pablos.ees.hokudai.ac.jp/irino/
https://pablos.ees.hokudai.ac.jp/irino/en/

Achievement

Research Interests

• 古気候学   sedimentology   stratigraphy   inorganic geochemistry   isotope geochemistry   

Research Areas

• Natural sciences / Solid earth science

Research Experience

• 2022/02 - Today Hokkaido University Faculty of Environmental Earth Science Associate Professor
• 2007/04 - 2022/01 Hokkaido University Faculty of Environmental Earth Science Assistant Professor
• 2005/04 - 2007/03 Hokkaido University Faculty of Environmental Earth Science Research Associate
• 2000/10 - 2005/03 Hokkaido University Graduate School of Environmental Earth Science Research Associate
• 1999/01 - 2000/09 Japan Science and Technology Corporation Domestic Research Fellow
• 1996/01 - 1998/12 Japan Society for the Promotion of Science Research Fellow (PD)

Education

• 1993/04 - 1996/11  The University of Tokyo  Graduate School of Science  Geology
• 1990/04 - 1993/03  The University of Tokyo  Graduate School of Science  Geology
• 1988/04 - 1990/03  The University of Tokyo  Faculty of Science  Department of Geological Sciences
• 1985/04 - 1988/03  The University of Tokyo  College of Arts and Sciences  Natural Sciences I

Awards

• 2019/09 日本地質学会 The Geological Society of Japan Best Paper Award
   Depositional ages and characteristics of Middle‒Upper Jurassic and Lower Cretaceous lacustrine deposits in southeastern Mongolia. Island Arc 27-3, 2018. DOI: 10.1111/iar.12243 

  受賞者: Hasegawa, H;Ando, H;Hasebe, N;Ichinnorov, N;Ohta, T;Hasegawa, T;Yamamoto, M;Li, G;Erdenetsogt, B.-O;Heimhofer, U;Murata, T;Shinya, H;Enerel, G;Oyunjargal, G;Munkhtsetseg, O;Suzuki, N;Irino, T;Yamamoto, K
• 2014/06 Paleontological Society of Japan 2014 Best Paper Award
   Kitamura, A., Kobayashi, K., Tamaki, C., Yamamoto, N., Irino, T., Miyairi, Y., and Yokoyama, Y., Evidence of recent warming in the Okinawa region, subtropical northwestern Pacific, from an oxygen isotope record of a cave-dwelling marine micro-bivalve, Pal 

  受賞者: 北村晃寿;小林小夏;玉置周子;山本なぎさ;入野智久;宮入陽介;横山祐典
• 2010/08 日本第四紀学会 日本第四紀学会論文賞
   青木かおり・入野智久・大場忠道（2008）「鹿島沖海底コアMD01-2421の後期更新世テフラ層序」第四紀研究、47巻、6号、391-407. 

  受賞者: 青木かおり;入野智久;大場忠道

Published Papers

• Atmospheric particulates over the northwestern Pacific during the late Holocene: Volcanism, dust, and human perturbation

  Samuel K. Marx, James Hooper, Tomohisa Irino, Nicola Stromsoe, Krystyna M. Saunders, Osamu Seki, Anthony Dosseto, Andrea Johansen, Quan Hua, Florian Dux, Geraldine Jacobsen, Atun Zawadzki

  Science Advances 2024/10/25
• Orbital-scale competition of biogenic carbonate and opal production at the Del Caño Rise in the Indian sector of the Southern Ocean during the late Pleistocene 

  Hyuk Choi, Matthieu Civel-Mazens, Xavier Crosta, Isabelle Billy, Tomohisa Irino, Hiroyuki Takata, Sangbeom Ha, Boo-keun Khim

  2024/03/08
• Multiple episodes of ice loss from the Wilkes Subglacial Basin during the Last Interglacial

  Mutsumi Iizuka, Osamu Seki, David J. Wilson, Yusuke Suganuma, Keiji Horikawa, Tina van de Flierdt, Minoru Ikehara, Takuya Itaki, Tomohisa Irino, Masanobu Yamamoto, Motohiro Hirabayashi, Hiroyuki Matsuzaki, Saiko Sugisaki

  Nature Communications 14 (1) 2023/04/18 

  Abstract The Last Interglacial (LIG: 130,000–115,000 years ago) was a period of warmer global mean temperatures and higher and more variable sea levels than the Holocene (11,700–0 years ago). Therefore, a better understanding of Antarctic ice-sheet dynamics during this interval would provide valuable insights for projecting sea-level change in future warming scenarios. Here we present a high-resolution record constraining ice-sheet changes in the Wilkes Subglacial Basin (WSB) of East Antarctica during the LIG, based on analysis of sediment provenance and an ice melt proxy in a marine sediment core retrieved from the Wilkes Land margin. Our sedimentary records, together with existing ice-core records, reveal dynamic fluctuations of the ice sheet in the WSB, with thinning, melting, and potentially retreat leading to ice loss during both early and late stages of the LIG. We suggest that such changes along the East Antarctic Ice Sheet margin may have contributed to fluctuating global sea levels during the LIG.
• Beppu Bay, Japan, as a candidate Global Boundaries Stratotype Section and Point for an Anthropocene series

  Michinobu Kuwae, Bruce P Finney, Zhiyuan Shi, Aya Sakaguchi, Narumi Tsugeki, Takayuki Omori, Tetsuro Agusa, Yoshiaki Suzuki, Yusuke Yokoyama, Hirofumi Hinata, Yoshio Hatada, Jun Inoue, Kazumi Matsuoka, Misaki Shimada, Hikaru Takahara, Shin Takahashi, Daisuke Ueno, Atsuko Amano, Jun Tsutsumi, Masanobu Yamamoto, Keiji Takemura, Keitaro Yamada, Ken Ikehara, Tsuyoshi Haraguchi, Stephen Tims, Michaela Froehlich, Leslie Keith Fifield, Takahiro Aze, Kimikazu Sasa, Tsutomu Takahashi, Masumi Matsumura, Yukinori Tani, Peter R Leavitt, Hideyuki Doi, Tomohisa Irino, Kazuyoshi Moriya, Akira Hayashida, Kotaro Hirose, Hidekazu Suzuki, Yoshiki Saito

  The Anthropocene Review 205301962211350 - 205301962211350 2053-0196 2022/12/19 [Refereed][Not invited]
   

  For assessment of the potential of the Beppu Bay sediments as a Global Boundaries Stratotype Section and Point (GSSP) candidate for the Anthropocene, we have integrated datasets of 99 proxies. The datasets for the sequences date back 100 years for most proxy records and 1300 years for several records. The cumulative number of occurrences of the anthropogenic fingerprint reveal unprecedented increases above the base of the 1953 flood layer at 64.6 cm (1953 CE), which coincides with an initial increase in global fallout of ²³⁹Pu+²⁴⁰Pu. The onset of the proliferation of anthropogenic fingerprints was followed by diverse human-associated events, including a rapid increase in percent modern ¹⁴C in anchovy scales, changes in nitrogen and carbon cycling as recorded by anchovy δ¹⁵N and δ¹³C, elevated pollution of heavy metals, increased depositions of novel materials (spheroidal carbonaceous particles, microplastics, polychlorinated biphenyls), the occurrence of hypoxia (Re/Mo ratio) and eutrophication (biogenic opal, TOC, TN, diatoms, chlorophyll a), unprecedented microplankton community changes (compositions of carotenoids, diatoms, dinoflagellates), abnormally high spring air temperatures as inferred from diatom fossils, and lithological changes. These lines of evidence indicate that the base of the 1953 layer is the best GSSP level candidate in the stratigraphy at this site.
• Geological controls on dispersal and deposition of river flood sediments on the Hidaka shelf, Northern Japan

  Ken Ikehara, Hajime Katayama, Tsumoru Sagayama, Tomohisa Irino

  Geological Society, London, Special Publications SP505 - 2019 2022/09/06 [Refereed]
  
• Benthic foraminifera in the Nakdong River Delta (southeast Korea) and their response to middle Holocene climatic change in the coastal environment of the East Asian margin

  Hiroyuki Takata, Tomohisa Irino, Kota Katsuki, Han Jun Woo, Jun-Ho Lee, Hyoun Soo Lim, Sangbeom Ha, Boo-Keun Khim

  Journal of Asian Earth Sciences 2022/08
• Aleutian Low variability for the last 7500 years and its relation to the Westerly Jet

  Kana Nagashima, Jason Addison, Tomohisa Irino, Takayuki Omori, Kei Yoshimura, Naomi Harada

  Quaternary Research 108 161 - 179 0033-5894 2022/07 [Refereed]
   

  Abstract The Aleutian Low (AL) is one of the major atmospheric systems that determines environmental conditions during winter in the North Pacific Ocean, with impacts that affect the climates of both Asia and North America from mid- to high latitudes. However, the multi-centennial and longer scale behavior of the AL during the Holocene is not fully understood. In this study, AL variability since 7.5 ka was examined by applying the principal component analysis technique to published δ¹⁸O data derived from sedimentary calcite, peat, ice, and speleothem from western North America. The extracted Principal Component 1 (PC1) represents a dramatic change from the mid- to late Holocene, and appears to reflect long-term intensified AL related to interactions between orbitally-driven southward shift of the Westerly Jet (WJ) over East Asia and the northwestern Pacific, and intensification of the El Niño–Southern Oscillation. In contrast, PC2 is characterized by multi-centennial to millennial-scale oscillations, with a spatial loading pattern that suggests PC2 reflects AL intensity and position shifts. These oscillations are contemporaneous with both WJ latitude and/or the meandering path shifts over East Asia and solar activity change, suggesting that a decrease/increase in solar irradiance is related to AL variability via interactions with the WJ.
• Environmental evolution and fire history of Rebun Island (Northern Japan) during the past 17,000 years based on biomarkers and pyrogenic compound records from Lake Kushu

  Masanobu Yamamoto, Fangxian Wang, Tomohisa Irino, Kazuyoshi Yamada, Tsuyoshi Haraguchi, Hideto Nakamura, Katsuya Gotanda, Hitoshi Yonenobu, Christian Leipe, Xuan-Yu Chen, Pavel E. Tarasov

  QUATERNARY INTERNATIONAL 623 8 - 18 1040-6182 2022/06 

  Rebun is a small island located northwest of Hokkaido Island where hunter-fisher-gatherer cultural traditions continued until the 19th century CE. In this study, we quantified polycyclic aromatic hydrocarbons (PAHs), pentacyclic triterpene methyl ethers (PTMEs), n-fatty acids, and glycerol dialkyl glycerol tetraethers (GDGTs) in sediments from Lake Kushu in northern Rebun Island to reconstruct changes in limnology, the local environment and local to regional fire activities during the past 17,000 years (i.e., 17 ka). The PAH concentration increased from 11 to 10 cal ka BP. PAH and PTME compositions indicate that this change was associated with an increase of fire activity at proximal locations (i.e., the vicinity of Lake Kushu) and a change in the composition of grasses growing around the lake. A peak in PAH concentrations at 6.6-6.0 cal ka BP likely indicates intensive fire activity on Rebun Island. The PAH composition after 6 cal ka BP mainly reflected the combustion of conifers near the lake. The GDGTs, n-fatty acids, perylene, and PTME concentrations were higher around 10 cal ka BP and after 6 cal ka BP compared to the remaining periods, suggesting better preservation of those compounds under lake conditions marked by lower oxygen concentrations.
• Late Holocene centennial to millennial-scale variability in lower trophic level productivity off southern Hokkaido, Japan, and its response to dissolved iron-replete Coastal Oyashio dynamics

  Michinobu Kuwae, Narumi Tsugeki, Bruce P. Finney, Yukinori Tani, Jonaotaro Onodera, Mako Kiyoto, Mitsukuni Kusaka, Takuya Sagawa, Yugo Nakamura, Hiroji Ohnishi, Hiroshi Kuroda, Noboru Okuda, Tamihisa Ohta, Minoru Ikehara, Tomohisa Irino

  Quaternary Research 107 1 - 16 0033-5894 2022/02/22 

  Abstract Little is known about the dynamics of marine food chains spanning primary to higher trophic levels on centennial and longer timescales, especially where the supply of dissolved iron limits primary productivity. To elucidate the long-term dynamics of biological productivity in the Coastal Oyashio (CO), which is a major pathway for transporting dissolved iron into the western North Pacific from winter to spring, we reconstructed the lower trophic level productivity over the last 3000 years in the CO. Our results demonstrate that the concentrations and mass accumulation rates of both Chl-a (chlorophyll a and its derivatives) and biogenic opal used as proxies of primary productivity, and steryl chlorin esters (SCEs) used as that of zooplankton productivity, show a millennial-scale increasing trend and centennial-scale variability beginning ca. AD 400. SCEs were positively correlated with Chl-a, indicating that changes in zooplankton productivity were induced by bottom-up control of primary productivity. The Chl-a and SCEs showed synchronous centennial-scale patterns with a relative abundance of sea-ice-associated diatom species transported by CO, and with a ventilation index in the Okhotsk Sea Intermediate Water. This synchronous pattern indicates that lower trophic-level productivity during the spring bloom responded to the intensity of iron-replete CO.
• Orbital-scale vegetation-ocean-atmosphere linkages in western Japan during the last 550 ka based on a pollen record from the IODP site U1427 in the Japan Sea

  Ryoma Hayashi, Takuya Sagawa, Tomohisa Irino, Ryuji Tada

  Quaternary Science Reviews 267 107103 - 107103 0277-3791 2021/09 [Refereed]
  
• A Lacustrine Biomarker Record From Rebun Island Reveals a Warm Summer Climate in Northern Japan During the Early Middle Holocene Due to a Stronger North Pacific High

  Masanobu Yamamoto, Fangxian Wang, Tomohisa Irino, Kenta Suzuki, Kazuyoshi Yamada, Tsuyoshi Haraguchi, Katsuya Gotanda, Hitoshi Yonenobu, Xuan-Yu Chen, Pavel Tarasov

  FRONTIERS IN EARTH SCIENCE 9 2021/06 [Refereed]
   

  The summer climate of northern Japan since the last glacial period has likely been determined by atmospheric and oceanic dynamics, such as changes in the North Pacific High, the position of the westerlies, the Kuroshio Current, the Tsushima Warm Current (TWC), and the East Asian summer monsoon. However, it is unclear which factor has been most important. In this study, we analyzed leaf wax delta C-13 and delta D and glycerol dialkyl glycerol tetraethers (GDGTs) in sediments from Lake Kushu, Rebun Island, northern Japan, and discuss changes in climate over the past 17,000 years. The GDGT-based temperature, the averaged chain length, delta C-13 and delta D of long-chain n-fatty acids indicated that the climate was cold during the Oldest Dryas period similar to 16 ka and warm in the early Middle Holocene from similar to 9 to 6 ka. This climate change is consistent with the sea surface temperature in the Kuroshio-Oyashio transition, but inconsistent with changes in the TWC in the Sea of Japan. The results imply that the summer climate of northern Japan was controlled mainly by changes in the development of the North Pacific High via changes in the position of the westerly jet and East Asian summer monsoon rainfall, whereas the influence of the TWC was limited over a millennial timescale.
• Variations in sediment lithology of submarine flood deposits on the slope off Kumano River, Japan

  Ken Ikehara, Kazuko Usami, Tomohisa Irino

  Geological Society, London, Special Publications SP501 - 2019 2021/01/07 [Refereed]
  
• The 2011 Tohoku-oki tsunami-induced sediment remobilization on the Sendai shelf, Japan, from a comparison of pre- and post-tsunami surface sediments

  Ikehara, K., Irino, T., Saito, Y.

  Scientific Reports 11 (1) 2045-2322 2021
• Characteristics and distribution of the event deposits induced by the 2011 Tohoku-oki earthquake and tsunami offshore of Sanriku and Sendai, Japan

  Ken Ikehara, Kazuko Usami, Tomohisa Irino, Akiko Omura, Robert G. Jenkins, Juichiro Ashi

  Sedimentary Geology 411 105791 - 105791 0037-0738 2021/01 [Refereed]
  
• Provenance changes in fine detrital quartz in the inner shelf sediments of the East China Sea associated with shifts in the East Asian summer monsoon front during the last 6 kyrs

  Ke Wang, Ryuji Tada, Hongbo Zheng, Tomohisa Irino, Bin Zhou, Keita Saito

  Progress in Earth and Planetary Science 7 (1) 2197-4284 2020/12/01 

  The inner shelf sediments of the East China Sea (ECS) preserve valuable information regarding climatic changes on land through detrital material discharged from large rivers, particularly the Yangtze River. In this paper, we examine the provenance changes of fine-grained detrital quartz preserved in the sediment of the MD06-3040 core retrieved from the mud belt on the inner shelf of the ECS during the last 6 kyrs. The provenance of the fine silt fraction (4–16 μm) of the sediments, which is considered to represent the suspended particulate matter (SPM) from the Yangtze River, is estimated based on the electron spin resonance (ESR) signal intensity and crystallinity index (CI) of quartz. By comparing the ESR signal intensity and CI of quartz in the fine silt fraction of sediments to those from different parts of tributaries in the modern Yangtze River drainage, we can discriminate the SPM sourced from the northwestern and southeastern tributaries of the Yangtze River. Shifts in the East Asian summer monsoon (EASM) front are monitored by changes in the main precipitation areas which are manifested as changes in source rock ages and types implied from the ESR signal intensity and CI of quartz in the fine silt fraction of the studied sediments discharged from the Yangtze River. Temporal changes in provenance of the fine silt fraction through time suggest that shifts in the main location of EASM precipitation (most likely representing the EASM front) occurred at a multi-centennial-to-millennial scale with the deepest northwestward penetration of the EASM precipitation front (an enhanced EASM) occurring during the period 3.5–2.0 kyr BP and a southeastward retreat (a weak EASM) occurring during the periods 6.0–4.1 and 2.0–0 kyr BP. [Figure not available: see fulltext.].
• Intercomparison of XRF Core Scanning Results From Seven Labs and Approaches to Practical Calibration

  Ann G. Dunlea, Richard W. Murray, Ryuji Tada, Carlos A. Alvarez‐Zarikian, Chloe H. Anderson, Adrian Gilli, Liviu Giosan, Thomas Gorgas, Rick Hennekam, Tomohisa Irino, Masafumi Murayama, Larry C. Peterson, Gert‐Jan Reichart, Arisa Seki, Hongbo Zheng, Martin Ziegler

  Geochemistry, Geophysics, Geosystems 21 (9) 2020/09 [Refereed]
   

  X-ray fluorescence (XRF) scanning of marine sediment has the potential to yield near-continuous and high-resolution records of elemental abundances, which are often interpreted as proxies for paleoceanographic processes over different time scales. However, many other variables also affect scanning XRF measurements and convolute the quantitative calibrations of element abundances and comparisons of data from different labs. Extensive interlab comparisons of XRF scanning results and calibrations are essential to resolve ambiguities and to understand the best way to interpret the data produced. For this study, we sent a set of seven marine sediment sections (1.5 m each) to be scanned by seven XRF facilities around the world to compare the outcomes amidst a myriad of factors influencing the results. Results of raw element counts per second (cps) were different between labs, but element ratios were more comparable. Four of the labs also scanned a set of homogenized sediment pellets with compositions determined by inductively coupled plasma-optical emission spectrometry (ICP-OES) and ICP-mass spectrometry (MS) to convert the raw XRF element cps to concentrations in two ways: a linear calibration and a log-ratio calibration. Although both calibration curves are well fit, the results show that the log-ratio calibrated data are significantly more comparable between labs than the linearly calibrated data. Smaller-scale (higher-resolution) features are often not reproducible between the different scans and should be interpreted with caution. Along with guidance on practical calibrations, our study recommends best practices to increase the quality of information that can be derived from scanning XRF to benefit the field of paleoceanography.
• Cyclostratigraphy of the Late Miocene to Pliocene sediments at IODP sites U1425 and U1430 in the Japan Sea and paleoceanographic implications

  Shunsuke Kurokawa, Ryuji Tada, Kenji M. Matsuzaki, Tomohisa Irino, Lofi Johanna

  Progress in Earth and Planetary Science 6 (1) 2019/12/01 

  High-resolution studies of sedimentary sequences have reconstructed paleoceanographic changes in the Atlantic and southern and equatorial Pacific Oceans during the Late Miocene and Pliocene, but comparable analyses are lacking for the North Pacific Ocean. However, continuous samples of hemipelagic sequences covering this time interval were obtained at Integrated Ocean Drilling Program sites U1425 and U1430 in the Japan Sea during expedition 346. Because the paleoceanography of the Japan Sea was sensitive to glacio-eustatic sea-level changes, changes in the sediment record are manifested as cyclic lithological changes. By using a gamma ray attenuation (GRA) density, which reflects biogenic silica content, as an indicator of sea-level changes, we developed an independent orbitally tuned chronology at each site to construct high-resolution, high-precision age models for the time span of 11.8 to 1.45 Ma. First, the 405-kyr-filtered GRA profile at each site was tuned to 405-kyr-filtered orbital eccentricity. Then, using the 405-kyr-tuned age model, the 100-kyr-filtered GRA profile was tuned to short-eccentricity cycles to adjust the 405-kyr-tuned age models. We used the resulting age models to revise the time intervals of previously published lithological units and paleoceanographic stages for the Japan Sea. Our profiles based on physical properties are a good match to the oxygen isotope record, except for 6.6–3.6 Ma, a time interval with small-amplitude fluctuations in the oxygen isotope record. [Figure not available: see fulltext.]
• Sources of atmospheric black carbon and related carbonaceous components at Rishiri Island, Japan: The roles of Siberian wildfires and of crop residue burning in China

  Chunmao Zhu, Yugo Kanaya, Hisayuki Yoshikawa-Inoue, Tomohisa Irino, Osamu Seki, Yasunori Tohjima

  Environmental Pollution 247 55 - 63 0269-7491 2019/04 [Refereed]
   

  A field study was conducted to clarify sources of atmospheric black carbon and related carbonaceous components at Rishiri Island, Japan. We quantified equivalent black carbon (eBC) particle mass and the absorption Angstrom exponent (AAE), atmospheric CO and CH4, in addition to levoglucosan in total suspended particles, a typical tracer of biomass burning. Sixteen high eBC events were identified attributable to either anthropogenic sources or biomass burning in Siberia/China. These events were often accompanied by increases of co-emitted gases such as CH4 and CO. Specifically, we observed pollution events with elevated eBC, AAE, levoglucosan, and CH4-CO slope in late July 2014, which were attributed to forest fires in Siberia by reference to the FLEXPART model footprint and fire hotspots. In autumn, drastic increases of eBC, AAE, and levoglucosan were observed, accompanied by an eBC-CO slope of >15 ng m(-3)/ppb, resulting from long-range transport of emissions from extensive burning of crop residue on the Northeast China Plain. Other than the sources of fossil fuel combustion in China and forest fires in Siberia, we report for the first time that pollution events in northern Japan are caused by crop residue burning in China. This study elucidated valuable information that will improve understanding of the effects of biomass burning in East Asia on atmospheric carbonaceous components. (C) 2019 Elsevier Ltd. All rights reserved.
• Progress report of the project to specify the location and magnitude of the Australasian tektite impact event

  Tada Ryuji, Tada Toshihiro, Carling Paul, Songtham Wichanet, Le Xuen Thuyen, Kayama Masahiro, Chang Yu, Kurosawa Kosuke, Tajika Eiichi, Okada Makoto, Suganuma Yusuke, Irino Tomohisa, Kubota Yoshimi

  Annual Meeting of the Geological Society of Japan 一般社団法人 日本地質学会 2019 298  1348-3935 2019
• Construction of perfectly continuous records of physical properties for dark-light sediment sequences collected from the Japan Sea during Integrated Ocean Drilling Program Expedition 346 and their potential utilities as paleoceanographic studies

  Tomohisa Irino, Ryuji Tada, Ken Ikehara, Takuya Sagawa, Akinori Karasuda, Shunsuke Kurokawa, Arisa Seki, Song Lu

  Progress in Earth and Planetary Science 5 (1) 23 - 23 2018/12 [Refereed]
  
• Phylogenetic diversity and distribution of bacterial and archaeal amoA genes in the East China Sea during spring

  Kataoka, Takafumi, Suzuki, Koji, Irino, Tomohisa, Yamamoto, Masanobu, Higashi, Seigo, Liu, Hongbin

  Archives of Microbiology 200 (2) 2018 [Refereed]
  
• Integrated tephrostratigraphy and stable isotope stratigraphy in the Japan Sea and East China Sea using IODP Sites U1426, U1427, and U1429, Expedition 346 Asian Monsoon

  Sagawa, Takuya, Nagahashi, Yoshitaka, Satoguchi, Yasufumi, Holbourn, Ann, Itaki, Takuya, Gallagher, Stephen J., Saavedra-Pellitero, Mariem, Ikehara, Ken, Irino, Tomohisa, Tada, Ryuji

  Progress in Earth and Planetary Science 5 (1) 2018 [Refereed]
  
• High-resolution and high-precision correlation of dark and light layers in the Quaternary hemipelagic sediments of the Japan Sea recovered during IODP Expedition 346

  Tada, Ryuji, Irino, Tomohisa, Ikehara, Ken, Karasuda, Akinori, Sugisaki, Saiko, Xuan, Chuang, Sagawa, Takuya, Itaki, Takuya, Kubota, Yoshimi, Lu, Song, Seki, Arisa, Murray, Richard W., Alvarez-Zarikian, Carlos, Anderson, William T., Bassetti, Maria Angela, Brace, Bobbi J., Clemens, Steven C., da Costa Gurgel, Marcio H., Dickens, Gerald R., Dunlea, Ann G., Gallagher, Stephen J., Giosan, Liviu, Henderson, Andrew C. G., Holbourn, Ann E., Kinsley, Christopher W., nd Lee, Gwang Soo, Lee, Kyung Eun, Lofi, Johanna, Lopes, Christina I. C. D., Saavedra-Pellitero, Mariem, Peterson, Larry C., Singh, Raj K., Toucanne, Samuel, Wan, Shiming, Zheng, Hongbo, Ziegler, Martin

  Progress in Earth and Planetary Science 5 (1) 2018 [Refereed]
  
• Fluctuations in the East Asian monsoon recorded by pollen assemblages in sediments from the Japan Sea off the southwestern coast of Hokkaido, Japan, from 4.3 Ma to the present

  Igarashi, Y., Irino, T., Sawada, K., Song, L., Furota, S.

  Global and Planetary Change 163 2018 [Refereed]
  
• Evidence for surface sediment remobilization by earthquakes in the Nankai forearc region from sedimentary records

  Okutsu, Natsumi, Ashi, Juichiro, Yamaguchi, Asuka, Irino, Tomohisa, Ikehara, Ken, Kanamatsu, Toshiya, Suganuma, Yusuke, Murayama, Masafumi, Lintern, D. G., Campbell, P. T.

  Subaqueous Mass Movements. Geological Society 477 2018 [Refereed]
  
• Depositional ages and characteristics of Middle-Upper Jurassic and Lower Cretaceous lacustrine deposits in southeastern Mongolia

  Hasegawa, Hitoshi, Ando, Hisao, Hasebe, Noriko, Ichinnorov, Niiden, Ohta, Tohru, Hasegawa, Takashi, Yamamoto, Masanobu, Li, Gang, Erdenetsog, Bat-Orshikh, Heimhofer, Ulrich, Murata, Takayuki, Shinya, Hironori, Enerel, G., Oyunjargal, G., Munkhtsetseg, O., Suzuki, Noriyuki, Irino, Tomohisa, Yamamoto, Koshi

  Island Arc (December 2015) 2018 [Refereed]
  
• Biomass burning history in East Asia during the last 4 million years recorded in elemental carbon variability at IODP site U1423

  Lu, Song, Irino, Tomohisa, Igarashi, Yaeko

  Progress in Earth and Planetary Science 5 (1) 2018 [Refereed]
  
• Holocene dynamics in the Bering Strait inflow to the Arctic and the Beaufort Gyre circulation based on sedimentary records from the Chukchi Sea

  Masanobu Yamamoto, Seung-Il Nam, Leonid Polyak, Daisuke Kobayashi, Kenta Suzuki, Tomohisa Irino, Koji Shimada

  Climate of the Past 13 (9) 1111 - 1127 2017/09/08 [Refereed]
  
• Characteristics of shallow marine flood sediments by organic carbon analyses, examples from shelf sediments off Hidaka, southern Hokkaido, after the 2003 typhoon no.10

  大村亜希子, 大村亜希子, 池原研, 片山肇, 入野智久, 嵯峨山積, 嵯峨山積

  地質学雑誌 一般社団法人 日本地質学会 123 (5) 321‐333 - 333 0016-7630 2017/05 [Refereed][Not invited]
   

  We conducted an organic carbon analysis of flood sediments from the 2003 typhoon no. 10 off Hidaka, southern Hokkaido. Flood-induced sediments from the river mouth, inner shelf, outer shelf, and upper slope are rich in terrigenous organic carbon. Four years after the typhoon, flood sediments were found preserved in a topographic depression on the inner shelf, within an area protected from waves and currents. Stratigraphic variations in terrigenous organic carbon ratios in flood sediments from the depression reflect changes in river discharge with rainfall during the flood. Our results indicate that terrigenous material from the river mouth was continuously supplied and deposited on the shelf. These stratigraphic variations in the terrigenous organic carbon ratio could be significant in ongoing attempts to discriminate flood sediments from ancient turbidite successions.

• Detrital provenance of the Holocene sediments of the Beppu Bay based on mineral composition

  Irino Tomohisa, Maruyama Airi, Ikehara Ken, Yamamoto Masanobu, Kuwae Michinobu, Takemura Keiji

  Abstracts of Annual Meeting of the Geochemical Society of Japan 一般社団法人日本地球化学会 64 16 - 16 2017 

• The ACER pollen and charcoal database: a global resource to document vegetation and fire response to abrupt climate changes during the last glacial period

  Goni, Maria Fernanda Sanchez, Despra, Stephanie, Daniau, Anne-Laure, Bassino, Frank C., Polanco-Martinez, Josue M., Harrison, Sandy P., Allen, Judy R. M., Anderson, R. Sco, Behling, Hermann, Bonnefille, Raymonde, Burjachs, Francesc, Carrion, Jose S., Cheddadi, Rachid, Clark, James S., Combourieu-Nebout, Nathalie, Mustaphi, Colin J. Courtney, Debusk, Georg H., Dupon, Lydie M., Finch, Jemma M., Fletcher, William J., Giardini, Marco, Gonzalez, Catalina, Gosling, William D., Grigg, Laurie D., Grimm, Eric C., Hayashi, Ryoma, Helmens, Karin, Heusser, Linda E., Hill, Trevor, Hope, Geoffrey, Huntley, Brian, Igarashi, Yaeko, Irino, Tomohisa, Jacobs, Bonnie, Jimenez-Moreno, Gonzalo, Kawai, Sayuri, Kershaw, A. Peter, Kumon, Fujio, Lawson, Ian T., Ledru, Marie-Pierre, Lezine, Anne-Marie, Liew, Ping Mei, Magri, Donatella, Marchant, Rober, Margari, Vasiliki, Mayle, Francis E., McKenzie, G. Merna, Moss, Patrick, Mueller, Stefanie, Mueller, Ulrich C., Naughton, Filipa, Newnham, Rewi M., Oba, Tadamichi, Perez-Obiol, Ramon, Pini, Roberta, Ravazzi, Cesare, Roucoux, Katy H., Rucina, Stephen M., Scott, Louis, Takahara, Hikaru, Tzedakis, Polichronis C., Urrego, Dunia H., van Geel, Bas, Valencia, B. Guido, Vandergoes, Marcus J., Vincens, Annie, Whitlock, Cathy L., Willard, Debra A., Yamamoto, Masanobu

  Earth System Science Data 9 (2) 2017 [Refereed]
  
• Origin of the water-soluble organic nitrogen in the maritime aerosol

  Matsumoto, Kiyoshi, Yamamoto, Yuya, Nishizawa, Kotaro, Kaneyasu, Naoki, Irino, Tomohisa, Yoshikawa-Inoue, Hisayuki

  Atmospheric Environment 167 2017 [Refereed]
  
• Multidecadal, centennial, and millennial variability in sardine and anchovy abundances in the western North Pacific and climate-fish linkages during the late Holocene

  Kuwae, Michinobu, Yamamoto, Masanobu, Sagawa, Takuya, Ikehara, Ken, Irino, Tomohisa, Takemura, Keiji, Takeoka, Hidetaka, Sugimoto, Takashige

  Progress in Oceanography 159 2017 [Refereed]
  
• Estimation of Evolutionary Rates of Mitochondrial DNA in Two Japanese Wood Mouse Species Based on Calibrations with Quaternary Environmental Changes

  Hanazaki, Kaori, Tomozawa, Morihiko, Suzuki, Yutaro, Kinoshita, Gohta, Yamamoto, Masanobu, Irino, Tomohisa, Suzuki, Hitoshi

  Zoological Science 34 (3) 2017 [Refereed]
  
• ESR signal intensity of quartz in the fine-silt fraction of riverbed sediments from the Yangtze River: a provenance tracer for suspended particulate matter

  Saito, Keita, Tada, Ryuji, Zheng, Hongbo, Irino, Tomohisa, Luo, Chao, He, Mengying, Wang, Ke, Suzuki, Yoshiaki

  Progress in Earth and Planetary Science 4 2017 [Refereed]
  
• Palaeobotanical records from Rebun Island and their potential for improving the chronological control and understanding human-environment interactions in the Hokkaido Region, Japan

  Mueller, Stefanie, Schmidt, Mareike, Kossler, Annette, Leipe, Christian, Irino, Tomohisa, Yamamoto, Masanobu, Yonenobu, Hitoshi, Goslar, Tomasz, Kato, Hirofumi, Wagner, Mayke, Weber, Andrzej W., Tarasov, Pavel E.

  Holocene 26 (10) 2016 [Refereed]
  
• Mass accumulation rate of detrital materials in Lake Suigetsu as a potential proxy for heavy precipitation: a comparison of the observational precipitation and sedimentary record

  Suzuki, Yoshiaki, Tada, Ryuji, Yamada, Kazuyoshi, Irino, Tomohisa, Nagashima, Kana, Nakagawa, Takeshi, Omori, Takayuki

  Progress in Earth and Planetary Science 3 2016 [Refereed]
  
• Documenting large earthquakes similar to the 2011 Tohoku-oki earthquake from sediments deposited in the Japan Trench over the past 1500 years

  Ikehara, Ken, Kanamatsu, Toshiya, Nagahashi, Yoshitaka a, Strasser, Michael, Fink, Hiske, Usami, Kazuko, Irino, Tomohisa, Wefer, Gerold

  Earth and Planetary Science Letters 445 2016 [Refereed]
  
• Distribution of detrital minerals and sediment color in western Arctic Ocean and northern Bering Sea sediments: Changes in the provenance of western Arctic Ocean sediments since the last glacial period

  Kobayashi, Daisuke, Yamamoto, Masanobu, Irino, Tomohisa, Nam, Seung-Il, Park, Yu-Hyeon, Harada, Naomi, Nagashima, Kana, Chikita, Kazuhisa, Saitoh, Sei-Ichi

  Polar Science 10 (4) 2016 [Refereed]
  
• Asian dust transport during the last century recorded in Lake Suigetsu sediments

  Nagashima, Kana, Suzuki, Yoshiaki, Irino, Tomohisa, Nakagawa, Takeshi, Tada, Ryuji, Hara, Yukari, Yamada, Kazuyoshi, Kurosaki, Yasunori

  Geophysical Research Letters 43 (6) 2016 [Refereed]
  
• Expedition 346 summary

  R. Tada, R.W. Murray, C.A. Alvarez Zarikian, W.T. Jr. Anderson, M.-A. Bassetti, B.J. Brace, S.C. Clemens, M.H. da Costa Gurgel, G.R. Dickens, A.G. Dunlea, S.J. Gallagher, L. Giosan, A.C.G. Henderson, A.E. Holbourn, K. Ikehara, T. Irino, T. Itaki, A. Karasuda, C.W. Kinsley, Y. Kubota, G.S. Lee, K.E. Lee, J. Lofi, C.I.C.D. Lopes, L.C. Peterson, M. Saavedra-Pellitero, T. Sagawa, R.K. Singh, S. Sugisaki, S. Toucanne, S. Wan, C. Xuan, H. Zheng, M. Ziegler

  Proceedings of the IODP 2015/03/28 [Not refereed]
  
• The reports on the session "A-HW27 Water and material transport and cycle in watersheds: from headwater to coastal area" in JPGU2015

  YOSHIKAWA Seiko, KOBAYASHI Masahiro, SAITO Mitsuyo, NAKAYA Shinji, ONODERA Shinichi, OKUDA Noboru, CHIKITA Kazuhisa, IRINO Tomohisa

  Japanese Journal of Soil Science and Plant Nutrition 一般社団法人 日本土壌肥料学会 86 (6) 592 - 594 0029-0610 2015
• Terrestrial plant biomarkers analyses in a sediment core from Japan Sea off Hokkaido (IODP Exp.346 U1423 site)

  Aoyagi Chiaki, Sawada Ken, Furota Satoshi, Irino Tomohisa, Igarashi Yaeko

  Annual Meeting of the Geological Society of Japan 一般社団法人 日本地質学会 2015 195 - 195 2015
• Temporal variations in black carbon recorded on Rishiri Island, northern Japan

  Zhu, Chunmao, Yoshikawa-Inoue, Hisayuki, Tohjima, Yasunori, Irino, Tomohisa

  Geochemical Journal 49 (3) 2015 [Refereed]
  
• Ozone depletion in the interstitial air of the seasonal snowpack in northern Japan

  Nakayama, Momoko, Zhu, Chunmao, Hirokawa, Jun, Irino, Tomohisa, Yoshikawa-Inoue, Hisayuki

  Tellus Series B-Chemical and Physical Meteorology 67 2015 [Refereed]
  
• OSL dating of fine-grained quartz from Holocene Yangtze delta sediments

  Sugisaki, Saiko, Buylaert, Jan-Pieter, Murray, Andrew, Tada, Ryuji, Zheng, Hongbo, Ke, Wang, Saito, Keita, Chao, Luo, Li, Shiyi, Irino, Tomohisa

  Quaternary Geochronology 30 2015 [Refereed]
  
• Possible submarine tsunami deposits on the outer shelf of Sendai Bay, Japan resulting from the 2011 earthquake and tsunami off the Pacific coast of Tohoku

  Ken Ikehara, Tomohisa Irino, Kazuko Usami, Robert Jenkins, Akiko Omura, Juichiro Ashi

  Marine Geology 358 120 - 127 2014/12 [Refereed]
  
• Distribution, source and transportation of glycerol dialkyl glycerol tetraethers in surface sediments from the western Arctic Ocean and the northern Bering Sea

  Park, Y.-H., Yamamoto, M., Nam, S.-I., Irino, T., Polyak, L., Harada, N., Nagashima, K., Khim, B.-K., Chikita, K., Saitoh, S.-I.

  Marine Chemistry 165 2014 [Refereed]
  
• Tracing Sr isotopic composition in space and time across the Yangtze River basin

  Luo, Chao, Zheng, Hongbo, Tada, Ryuji, Wu, Weihua, Irino, Tomohisa, Yang, Shouye, Saito, Keita

  Chemical Geology 388 2014 [Refereed]
  
• Nutricline shoaling in the eastern Pacific warm pool during the last two glacial maxima

  Bin Shaari, Hasrizal, Yamamoto, Masanobu, Irino, Tomohisa, Oba, Tadamichi

  Journal of Oceanography 70 (1) 2014 [Refereed]
  
• Millennial-scale East Asian Summer Monsoon variability recorded in grain size and provenance of mud belt sediments on the inner shelf of the East China Sea during mid-to late Holocene

  Wang, Ke, Zheng, Hongbo, Tada, Ryuji, Irino, Tomohisa, Zheng, Yan, Saito, Keita, Karasuda, Akinori

  Quaternary International 349 2014 [Refereed]
  
• Dynamics of the turbidity current generated by the 2011 Tohoku-Oki earthquake and tsunami

  Arai Kazuno, Naruse Hajime, Kawamura Kiichiro, Irino Tomohisa, Ikehara Ken, Saitoh Yu, Murayama Masafumi, Miura Ryo, Hino Ryota, Ito Yoshihiro, Inazu Daisuke, Yokokawa Miwa, Izumi Norihiro

  Annual Meeting of the Geological Society of Japan 一般社団法人 日本地質学会 2013 042  1348-3935 2013
• 日本の亜熱帯域と温帯域におけるキクメイシ Dipsastraea speciosa （ Dana , 1846 ） の骨格成長

  永田, 俊輔, 杉浦, 薫, 入野, 智久, 渡邊, 剛, 山野, 博哉

  日本サンゴ礁学会誌 日本サンゴ礁学会 15 37 - 56 1345-1421 2013 [Refereed]
  
• Stratigraphy and wiggle-matching-based age-depth model of late Holocene marine sediments in Beppu Bay, southwest Japan

  Kuwae, Michinobu, Yamamoto, Masanobu, Ikehara, Ken, Irino, Tomohisa, Takemura, Keiji, Sagawa, Takuya, Sakamoto, Tatsuhiko, Ikehara, Minoru, Takeoka, Hidetaka

  Journal of Asian Earth Sciences 69 2013 [Refereed]
  
• Seasonal variations in planktonic foraminiferal flux and oxygen isotopic composition in the western North Pacific: Implications for paleoceanographic reconstruction

  Sagawa, Takuya, Kuroyanagi, Azumi, Irino, Tomohisa, Kuwae, Michinobu, Kawahata, Hodaka

  Marine Micropaleontology 100 11 - 20 0377-8398 2013 [Refereed]
   

  The oxygen isotopic composition (delta O-18) of planktonic foraminiferal shells in seafloor sediment provides information on past surface oceanography. Knowledge of seasonal and depth habitat, as well as the delta O-18 disequilibrium (vital effect), is essential to constrain the interpretation of sedimentary delta O-18. Here, we present a 1-year time series of planktonic foraminiferal shell fluxes and delta(18)Ofrom a sediment trap moored in the northwestern margin of the North Pacific. The vital effect and calcification depth for four species were estimated by comparing shell delta O-18 and the predicted values of equilibrium calcite calculated from temperature and estimated delta O-18 in seawater. Six major species (Neogloboquadrina incompta, Nedgloboquadrina dutertrei, Neogloboquadrina pachyderma, Globigerina quinqueloba, Globigerina bulloides, and Globorotalia scitula) constituted 97% of the total foraminiferal flux. Most major species showed large fluxes in June and December, corresponding to periods of the development and disruption of the seasonal thermocline, implying the importance of nutrient injection and/or circulation for foraminiferal fluxes. Additional peaks in N. dutertrei and N. pachyderma were observed in August. The seasonal successions of foraminiferal fluxes corresponded to surface ocean stratification conditions and food availability, which are closely related to circulation of local currents. Vital effect estimations suggest that shells calcified in equilibrium for G. bulloides and N. pachyderma [sinistral (s)1 and with a -0.7% offset for N. dutertrei [dextral (d)], a -1.0%, offset for N. incompta (d), and a -03% offset for N. pachyderma (d). The calculation of flux-weighted delta O-18 values reveals that the sedimentary delta O-18 values of G. bulloides, N. dutertrei (d), and N. incompta (d) reflect surface temperature in winter season, and those of N. pachyderma (s) and N. pachyderma (d) reflect summer and annual mean subsurface temperature, respectively. The shallow calcification depths for the four species suggest that delta O-18 between different species (Delta delta O-18) in the western North Pacific does not work for reconstructing past stratification conditions, unlike in other regions. Rather, the delta O-18 between N. pachyderma (s) and G. bulloides, N. dutertrei (d) or N. incompta (d) may be a more suitable proxy for past seasonality. (C) 2013 Elsevier B.V. All rights reserved.
• Evidence of recent warming in the Okinawa region, subtropical northwestern Pacific, from an oxygen isotope record of a cave-dwelling marine micro-bivalve

  Kitamura, Akihisa, Kobayashi, Konatsu, Tamaki, Chikako, Yamamoto, Nagisa, Irino, Tomohisa, Miyairi, Yosuke, Yokoyama, Yusuke

  Paleontological Research 17 (1) 2013 [Refereed]
  
• Enhanced upwelling in the eastern equatorial Pacific at the last five glacial terminations

  bin Shaari, Hasrizal, Yamamoto, Masanobu, Irino, Tomohisa

  Palaeogeography Palaeoclimatology Palaeoecology 386 2013 [Refereed]
  
• Variabilities in detrital supply and the marine environment at ODP Site 1237 in the southeast Pacific Ocean since the late Oligocene.

  Noma Eriko, Irino Tomohisa, Shaari Hasrizal, Yamamoto Masanobu

  Annual Meeting of the Geological Society of Japan 一般社団法人 日本地質学会 2012 214 - 214 2012
• Relationship between mineral and major element compositions of suspended materials of the Saru River, Hokkaido, and marine sediments at its river mouth

  Irino Tomohisa, Yamashita Yohei, Seki Osamu, Ikehara Ken, Nagao Seiya

  Annual Meeting of the Geological Society of Japan 一般社団法人 日本地質学会 2012 220 - 220 2012
• Sea level at the last glacial maximum, constrained by oxygen isotopic curves of planktonic foraminifera in the Japan Sea

  Oba, Tadamichi, Irino, Tomohisa

  Journal of Quaternary Science 27 (9) 2012 [Refereed]
  
• Orbital- and millennial-scale paleoceanographic changes in the north-eastern Japan Basin, East Sea/Japan Sea during the late Quaternary

  Khim, Boo-Keun, Ikehara, Ken, Irino, Tomohisa

  Journal of Quaternary Science 27 (3) 2012 [Refereed]
  
• Distribution of glycerol dialkyl glycerol tetraethers, alkenones and polyunsaturated fatty acids in suspended particulate organic matter in the East China Sea

  Nakanishi, Takahiro, Yamamoto, Masanobu, Irino, Tomohisa, Tada, Ryuji

  Journal of Oceanography 68 (6) 2012 [Refereed]
  
• Relationship between the Andean volcanism and paleoclimatic /paleoceanographic changes based on ODP Site 1237 core

  Irino Tomohisa, Yamamoto Masanobu

  Abstracts of Annual Meeting of the Geochemical Society of Japan 日本地球化学会 58 110 - 110 2011 

  新生代における山地の隆起と気候変動の関係を検討するために、ペルー沖ODP Site 1237コアの鉱物・化学組成を検討する。特に堆積物コアに含まれる中央アンデス起源と思われる火山灰の寄与と砕屑物および海洋炭酸塩組成の分析を通して、この地域の長い時間スケールの火山活動と気候・海洋変動との間の関係を解析することを目的とした。コアは前期漸新世までおよんでおり、4 Maまでは95%以上が炭酸塩の軟泥である。砕屑鉱物組成が検討できた2.5 Ma以降では、火山活動の活発化に遅れて乾燥化が起こることが示唆された。
• Meridional Sea Surface Temperature Evolution in the Eastern Tropical Pacific during the Last Glacial Cycles

  bin Shaari Hasrizal, Yamamoto Masanobu, Irino Tomohisa

  Abstracts of Annual Meeting of the Geochemical Society of Japan 日本地球化学会 58 144 - 144 2011 

  ODPサイト1237, 1239, 1241の堆積物に含まれるグリセロール・ジアルキル・グリセロール・テトラエーテルを分析することにより過去１５万年間のTEX86古水温変動を求め，水温の緯度勾配の変化を検討した．
• Winter monsoon variability during the last 40,000 years; evidence from TEX86-derived temperatures in the northern East China Sea

  Yamamoto Masanobu, Nakanishi Takahiro, Kishizaki Midori, Irino Tomohisa, Tada Ryuji, Oda Hirokuni

  Abstracts of Annual Meeting of the Geochemical Society of Japan 日本地球化学会 58 142 - 142 2011 

  We discuss winter monsoon variability during the last 40,000 years, based on TEX86-derived temperature records from cores MD98-2195, KY0704 PC-1, and KY0704 PL-1 retrieved from the northern East China Sea.
• SPATIAL DISTRIBUTION OF Delta C-14 VALUES OF ORGANIC MATTER IN SURFACE SEDIMENTS OFF SARU RIVER IN NORTHERN JAPAN, ONE YEAR AFTER A FLOOD EVENT IN 2006

  Nagao, Seiya, Irino, Tomohisa, Aramaki, Takafumi, Ikehara, Ken, Katayama, Hajime, Otosaka, Shigeyoshi, Uchida, Masao, Shibata, Yasuyuki

  Radiocarbon 52 (3) 1068 - 1077 0033-8222 2010 [Refereed]
   

  Dispersion and deposition of terrestrial organic matter by flooding on the inner shelf were studied using C/N ratios, delta C-13, and Delta C-14 values of sedimentary organic matter. Surface sediment samples (top 2 cm) were collected from coastal areas near the Saru River in southwestern Hokkaido, northern Japan, 1 yr after a flood event in 2006. Riverine suspended solids were also collected at a fixed station downstream during 2006-2008. Sandy sediments were located at the front of the river mouth and the western part of the sampling area, with the delta C-13 of organic matter ranging from -23.8 parts per thousand to -22.0 parts per thousand, Delta C-14 of -655 parts per thousand to -388 parts per thousand, and an organic carbon/total nitrogen (C/N) ratio of 5.9-7.7. On the other hand, silt and clay sediments were distributed in a restricted area 11-16 km from the river mouth, with lighter delta C-13 (-26.7 parts per thousand to -24.1 parts per thousand) and higher Delta C-14 (-240 parts per thousand to -77 parts per thousand) of organic matter and C/N ratio (7.8-13.3). From end-member analysis, the apparently younger and less degraded organic matter in the silt and clay sediments consists mainly of terrestrial organic matter released by flood events. They remain in the depression, although most flood deposits were moved to deep-sea environments.
• Millennial-scale variability in vegetation records from the East Asian Islands: Taiwan, Japan and Sakhalin

  Takahara, Hikaru, Igarashi, Yaeko, Hayashi, Ryoma, Kumon, Fujio, Liew, Ping-Mei, Yamamoto, Masanobu, Kawai, Sayuri, Oba, Tadamichi, Irino, Tomohisa

  Quaternary Science Reviews 29 (21-22) 2010 [Refereed]
  
• Climatic and hydrologic variability in the East China Sea during the last 7000 years based on oxygen isotope records of the submarine cavernicolous micro-bivalve Carditella iejimensis

  Yamamoto, Nagisa, Kitamura, Akihisa, Irino, Tomohisa, Kase, Tomoki, Ohashi, Syu-ichi

  Global and Planetary Change 72 (3) 2010 [Refereed]
  
• Investigation on coral necrosis in massive Porites colony in the Mouth of Todoroki river, Ishigaki Island, Japan deduced from the δ^O, δ^C and Mn/Ca ratios

  KAWASHIMA Tatsunori, WATANABE Tsuyoshi, SHIRAI Kotaro, MAEKAWA Satoshi, SHIMAMURA Michiyo, IRINO Tomohisa, SANO Yuji

  Chikyukagaku 日本地球化学会 43 (1) 35 - 42 0386-4073 2009/03/30 [Refereed][Not invited]
   

  Coral reefs are increasingly faced to the crisis of decline and death caused by climate changes and anthropogenic influence. These crises were reported in Shiraho coral reefs, the Ishigaki Island, Southwestern Japan, caused by the red soils runoff through the Todoroki River. In order to evaluate the influence of terrestrial inputs on coral skeletal growth and coral death, we have analyzed oxygen and carbon isotopic ratios, as well as Mn/Ca ratio, of coral Porites, skeleton collected from Shiraho reef. The coral colony used in this study was still alive but partly dead when the samples were ...
• 北限サンゴ礁から採取されたキクメイシ属サンゴ骨格中の 酸素・炭素同位体比 -中緯度域における高時間分解能古気候アーカイブとしての検討-

  島村 道代, ヒョン キソン, 渡邊 剛, ソ インア, ユ チャンミン, 入野 智久, 杉原 薫, 山野 博哉

  日本地球化学会年会要旨集 日本地球化学会 56 29 - 29 2009 

  世界で最も高緯度に位置する、日本の壱岐サンゴ礁より採取されたキクメイシ属サンゴ骨中の酸素・炭素同位体比を分析し、中緯度域における高時間分解能古気候アーカイブとしての可能性を検討した。まず試料は莢壁と軸柱の骨格構造別に分析し、その結果を生育時の環境記録と対比・検討を行った。この結果、軸柱と莢壁は形成のタイミングが異なっており、キクメイシ属サンゴの場合、莢壁の方がより正確に環境を記録することがわかった。また本研究で用いたサンゴ骨格は、骨格構造自体にも成長パターンの季節的変化が見られた。これらの成果を基に、さらに長期に渡る骨格分析を行い、これらを周辺の環境と対比・検討したのでその成果を報告する。
• Geochemical perspective on coral skeletal growth of temperate Porites and Favia

  Kawamura Takashi, Watanabe Tsuyoshi, Sowa Kohki, Sakamoto Tatsuhiko, Irino Tomohisa, Shimamura Michiyo, Hyeong Kiseong, Sugihara Kaoru, Yamano Hiroya

  Abstracts of Annual Meeting of the Geochemical Society of Japan 日本地球化学会 56 25 - 25 2009 

  造礁性サンゴ骨格を用いた古環境復元においては、これまで塊状の群体を形成するハマサンゴ属が主に用いられてきた。キクメイシ属の塊状群体は、ハマサンゴ属のそれよりもさらに高緯度の地域でみられることから、ハマサンゴ属よりも低水温に適応していると考えられている。したがってキクメイシ属の骨格は、従来造礁性サンゴ骨格があまりターゲットにしてこなかった温帯地域での古環境指標として広く利用できる可能性を秘めている。鹿児島県甑島は温帯性の気候帯に属し、ハマサンゴ属とキクメイシ属がどちらも生息している。本研究では、甑島産のハマサンゴとキクメイシの軟X線画像による密度バンドと骨格中の酸素安定同位体比を用いて、両種のサンゴの温帯地域における骨格成長の季節性と、古水温指標としての可能性を比較・検討した。
• 太平洋中層での浮遊性有孔虫殻の溶解と二次石灰化およびその同位体比への影響

  入野 智久, 太田 晴美, 大場 忠道

  日本地球化学会年会要旨集 日本地球化学会 56 128 - 128 2009 

  氷期-間氷期サイクルに伴う大気中CO2濃度の変動には、海洋の炭素循環が大きな役割を果たしていることは確かであるが、炭酸塩の保存・溶解がどの程度寄与しているかを定量的に言うことは依然として難しい。また太平洋は大きいので炭素収支への寄与も大きいことは確かだが、海盆全体が深いことととCCDが浅いことのために、中層での炭酸塩保存・溶解が十分には評価されてきていない。そこで本研究では、日本南岸の外洋域において、海洋表層に死骸で浮遊していたもの・セディメントトラップで回収された水柱を沈降中のもの・表層堆積物の３通りの試料から浮遊性有孔虫Globigerinoides sacculiferの完全個体を50-70個ずつ集め、そのサイズ・重量・酸素炭素安定同位体比を一個体ずつについて分析することを通して、浮遊性有孔虫殻の重量変化過程を明らかにするとともに、過去の溶解程度の変動とその同位体比への影響を検討した。
• The 1500-year climate oscillation in the midlatitude North Pacific during the Holocene

  Isono, Dai, Yamamoto, Masanobu, Irino, Tomohisa, Oba, Tadamichi, Murayama, Masafumi, Nakamura, Toshio, Kawahata, Hodaka

  Geology 37 (7) 2009 [Refereed]
  
• Holocene temperature change in the northern East China Sea

  Nakanishi Takahiro, Yamamoto Masanobu, Okino Tatsufumi, Irino Tomohisa, Oda Hirokuni, Yokoyama Yusuke, Matsuzaki Hiroyuki, Tada Ryuji

  Abstracts of Annual Meeting of the Geochemical Society of Japan 日本地球化学会 55 414 - 414 2008 

  KY07-04航海により採取されたピストンコアPC-1とマルチプルコアPL-1を使用して、東シナ海北部の過去5000年間の表層水温を、バイオマーカー指標であるアルケノンに基づくU^K₃₇'とGDGT指標であるTEX₈₆を用いて、40年から80年間隔と時間的解像度を高めて水温変動を復元した。アルケノン水温は過去5000年間に渡って23.5℃から24℃とほぼ一定の値を示した。一方、TEX₈₆水温はアルケノン水温とは異なり、20.4℃から24.8℃の間で激しく変動した。両者の水温変動に違いが見られる理由として、それぞれの物質をつくる生物の生息時期や深度の違いが挙げられるが、GDGTをつくるクレンアーキオータの生息深度は不明である。これを解決する手段として、本年５月に行われたKT08-10航海にてコアサイト付近の表層から中層の海水を採取し、ろ過後脂質を抽出し、GDGTを分析した。発表では、海水より求めたTEX₈₆水温の結果も合わせて報告する。
• Development of non-destructive and expeditious analysis of coral skeleton for reconstructing paleo-environment ; Coral skeletal growth from digitized images of X-radiographs and chemical compositional variants from Non-Destructive X-Ray Fluorescence

  SOWA KOHKI, WATANABE TSUYOSHI, SAKAMOTO TATSUHIKO, IJIMA KOHICHI, TAKASAWA MASAYOSHI, IRINO TOMOHISA, Aguilar Yolanda M., KASE TOMOKI

  Abstracts of Annual Meeting of the Geochemical Society of Japan 日本地球化学会 55 408 - 408 2008 

  本研究では, 非破壊かつ迅速で簡便にサンゴ骨格成長量と俯瞰的な化学組成変動(数ヶ月程度の解像度での季節変動)を捉える分析手法を開発することが目的である。具体的には, 軟X線写真,非破壊蛍光X線地殻コアロガー・微少領域対応型（TATSCAN-F1）とコア対応型(TATSCAN-F2)を用いて, サンゴ骨格成長量と俯瞰的な化学組成変動を時系列に沿って分析する。本研究手法の確立により, 最大150cm長のサンゴコア(推定年齢150年程度)のサンゴ骨格成長量と俯瞰的な化学組成変動を, サンゴコアを数枚に切断することなく, 非破壊で数日以内に分析できる。本講演では, 我々がこれまで鋭意進めてきたそれらの手法の可能性と開発成果を報告する。
• Reconstruction of seasonal sea surface temperature variability in the Japan Sea during the Last Glacial Maximum based on oxygen isotope composition of bivalve

  Tada Keigo, Irino Tomohisa, Kitamura Akihisa, Ikehara Ken

  Abstracts of Annual Meeting of the Geochemical Society of Japan 日本地球化学会 55 417 - 417 2008 

  現在、東アジア東縁域は季節性のあるモンスーン域にあたる。モンスーン変動の仕組みを解明するためにはこのような季節性が過去にどうであったかを明らかにする必要がある。現在の日本海表層水はモンスーンの季節性を反映している。しかし、LGMは過去の研究から日本海表層水の低塩分化は確実であるが、水温変化については見解が一致していない。加えて、その情報はブルーミング時期に集中している。これらの問題点を克服するために、水温・塩分の連続的な季節変動を記録していると期待される二枚貝化石を用いてLGMの日本海表層の水温季節変動幅の復元を行った。得られた結果から対象とした二枚貝のうちPatinopecten yessoensisの年代は22112±112 cal yr BPでLGMにあたる。P. yessoensisのδ18Oは周期的な変動を示し、夏期にあたる最小値は0.7‰でありOba et al., (1991)のLGMにおける浮遊性有孔虫のδ18O値と一致していた。また、過去の研究では不明であった冬期の酸素同位体比の最大値は3.0‰であった。
• 鹿島沖海底コアMD01-2421の後期更新世テフラ層序

  青木, かおり, 入野, 智久, 大場, 忠道

  第四紀研究 47 (6) 2008 [Refereed]
  
• Opposed trend of skeletal carbon isotopic ratios found in two different coral species collected from the same site: Genus-dependent responses

  Shimamura, Michiyo, Hyeong, K., Watanabe, Tsuyoshi, Irino, Tomohisa, Yoo, Chan Min, Kim, W. S.

  Proc 11th Int Coral Reef Symp (4) 2008 [Refereed]
  
• Reconstruction of paleotemperatures in the Northwest Pacific over the past 3000 years from delta(18)O values of the micro-bivalvia Carditella iejimensis found in a submarine cave

  Yamamoto, Nagisa, Kitamura, Akihisa, Irino, Tomohisa, Kase, Tomoki, Ohashi, Syu-ichi

  Global and Planetary Change 62 (1-2) 2008 [Refereed]
  
• Main controlling factors of coral skeletal carbon isotopic composition and skeletal extension rate: High-resolution study at Hainan Island, South China Sea

  Shimamura, Michiyo, Irino, Tomohisa, Oba, Tadamichi, Xu, Guoqiang, Lu, Bingquan, Wang, Luejiang, Toyoda, Kazuhiro

  Geochemistry Geophysics Geosystems 9 2008 [Refereed]
  
• High resolution stable isotope records of sclreractinian corals near Ishigaki Island: Their implication as a potential paleoclimatic recorder in middle latitude regions

  Shimamura, Michiyo, Hyeong, Kiseong, Yoo, Chan Min an, Watanabe, Tsuyoshi, Irino, Tomohisa, Jung, Hoi-Soo

  Geosciences Journal 12 (1) 2008 [Refereed]
  
• 北海道日高沖陸棚上における 2003 年洪水後の表層堆積物分布

  片山, 肇, 池原, 研, 菅, 和哉 an, 嵯峨山, 積, 入野, 智久, 辻野, 匠, 井上, 卓彦

  地質調査研究報告 58 2007 [Not refereed]
  
• Potential of submarine-cave sediments and oxygen isotope composition of cavernicolous micro-bivalve as a late Holocene paleoenvironmental record

  Kitamura, Akihisa, Yamamoto, Nagisa, Kase, Tomoki, Ohashi, Shu-ichi, Hiramoto, Mayumi, Fukusawa, Hitoshi an, Watanabe, Tsuyoshi, Irino, Tomohisa, Kojitani, Hiroshi, Shimamura, Michiyo, Kawakami, Ikuo

  Global and Planetary Change 55 (4) 2007 [Refereed]
  
• Orbital-scale stratigraphy and high-resolution analysis of biogenic components and deep-water oxygenation conditions in the Japan Sea during the last 640 kyr

  Kido, Yoshiki, Minami, Ikue, Tada, Ryuji, Fujine, Kazuho, Irino, Tomohisa, Ikehara, Ken, Chun, Jong-Hwa

  Palaeogeography Palaeoclimatology Palaeoecology 247 (1-2) 2007 [Refereed]
  
• Orbital- and millennial-scale variations in Asian dust transport path to the Japan Sea

  Nagashima, Kana, Tada, Ryuji, Matsui, Hiroyuki, Irino, Tomohisa, Tani, Atsushi, Toyoda, Shin

  Palaeogeography Palaeoclimatology Palaeoecology 247 (1-2) 2007 [Refereed]
  
• Deep water ventilation in the northwestern North Pacific during the last deglaciation and the early Holocene (15-5 cal. kyr BP) based on AMS C-14 dating

  Minoshima, Kayo, Kawahata, Hodaka, Irino, Tomohisa, Ikehara, Ken, Aoki, Kaori, Uchida, Masao, Yoneda, Minoru, Shibata, Yasuyuki

  Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions with Materials and Atoms 259 (1) 2007 [Refereed]
  
• 堆積物から紐解く自然災害 2003年北海道日高洪水堆積物の海域における堆積様式

  池原研, 片山肇, 嵯峨山積, 菅和哉, 辻野匠, 入野智久, 大村亜希子

  月刊地球 海洋出版 28 (8) 512 - 517 0387-3498 2006/08/01 [Not refereed][Not invited]
  
• O-59 Evaluation of carbonate dissolution during last glacial maximum based on weight distribution of planktonic foraminifer

  Irino Tomohisa, Ota Harumi, Oba Tadamichi

  Annual Meeting of the Geological Society of Japan 日本地質学会 2006 73 - 73 2006
• Paleoenvironmental change off Kashima of central Japan during the last 144,000 years based on planktonic foraminiferal assemblage

  Niimura Yasushi, Irino Tomohisa, Oba Tadamichi

  Fossils 日本古生物学会 79 4 - 17 0022-9202 2006 

  We reconstructed the oceanographic changes during the last 144 kyr off Kashima, central Japan, utilizing several planktonic foraminiferal species extracted from an IMAGES sediment core of 45.82m long (MD01-2421; 36°02'N latitude and 141°47'E longitude; water depth=2,224m). We proposed the results based on the temporal variation in Tf values, (ratio of warm water species)/(warm+cold water species), relative abundance of Neogloboquadrina pachyderma (Ehrenberg) (sinistral coiling), sea surface temperatures (SST) and the faunal similarity between the present core and the surface sediments along the Pacific side off the Japanese Islands together. These results suggest that the core site has experienced under the water mass condition similar to the present Oyashio Current off southeast Hokkaido (42-43°N) during the glacial maxima and the water mass similar to the present Kuroshio Current off south Kyushu to south coast of the Japanese Islands (31-33°N) during the interglacial maxima. The SST estimates at the core site using regional and global transfer functions indicate that the SSTs were lower by〜10℃ around the Last Glacial Maximum (LGM, in particular 19-18 ka) and Marine Isotope Stage (MIS) 6 maximum (135-129 ka) compared to the modern temperature, while the SSTs were higher by〜1℃ during mid-Holocene (8-7 ka) and at MIS 5a (77-76ka), MIS 5c (〜94 ka), MIS 5d (112-107 ka) and MIS 5e (122-119 ka). Most prominent changes off Kashima have occurred during the cold to warm transitions of MIS 6/5 and MIS 2/1, when the Oyashio Current occupied over the core site as well as during the LGM. However, the influence of the Kuroshio Current was more distinct during most of the last interglacial period (MIS-5) than today except short periods of MIS 5b (〜86 ka) and MIS 5d (〜115 ka).
• Paleoceanographic history around the Tsugaru Strait between the Japan Sea and the Northwest Pacific Ocean since 30 cal kyr BP

  Koizumi, Itaru, Tada, Ryuji, Narita, Hisashi, Irino, Tomohisa, Aramaki, Takafumi, Oba, Tadamichi, Yamamoto, Hirofumi

  Palaeogeography, Palaeoclimatology, Palaeoecology 232 (1) 2006 [Refereed]
  
• Paleoceanographic change off central Japan since the last 144,000 years based on high-resolution oxygen and carbon isotope records

  Oba, Tadamichi, Irino, Tomohisa, Yamamoto, Masanobu, Murayama, Masafumi, Takamura, Akira, Aoki, Kaori

  Global and Planetary Change 53 (1-2) 2006 [Refereed]
  
• Long term Aleutian Low dynamics and obliquity-controlled oceanic primary production in the mid-latitude western North Pacific (Core MD01-2421) during the last 145,000 years

  Ueshima, Toshinori, Yamamoto, Masanobu, Irino, Tomohisa, Oba, Tadamichi, Minagawa, Masao, Narita, Hisashi, Murayama, Masafumi

  Global and Planetary Change 53 (1-2) 2006 [Refereed]
  
• Changes of primary production and ocean circulation off Sanriku in the northwestern Pacific over the last 27kyr

  Minoshima Kayo, Kawahata Hodaka, Irino Tomohisa, Ikehara Ken, Uchida Masao, Shibata Yasuyuki

  Abstracts of Annual Meeting of the Geochemical Society of Japan 一般社団法人日本地球化学会 52 122 - 122 2005 

  三陸沖は、親潮・津軽暖流・黒潮がぶつかり合い、多数の渦が形成される複雑な水塊構造をなす海域である。渦の中でも冷水渦は亜表層から表層に栄養塩を供給しており、この海域の高い生物生産を支えていると考えられる。最終氷期から現在にかけて親潮フロントの位置や黒潮流軸の変動、津軽海峡の閉鎖などが報告されており、海洋環境の変動が生物生産へ大きな影響を与えたと予想される。そこで三陸沖で取られたピストンコア試料を用いて、有機炭素量・オパール量・アルケノン量の測定を行い、過去2万7千年間にわたり生物生産がどのように変動していたかを、これまでの研究と併せて検討を行った。
• Southern migration of westerlies in the Northern Hemisphere PEP II transect during the Last Glacial Maximum

  Ono, Y., Irino, T.

  Quaternary International 118 13 - 22 2004 [Refereed]
  
• Paleoceanography during the last 150 kyr off central Japan based on diatom floras

  Koizumi, I., Irino, T., Oba, T.

  Marine Micropaleontology 53 (3-4) 2004 [Refereed]
  
• Lithology of pelagic sediment cores (PC-2,3,7) recovered from northwestern Pacific on R/V "Kairei" KR02-15 cruise.

  IRINO TOMOHISA, SAGAWA TAKUYA, NIIMURA YASUSHI, KANAMATSU TOSHIYA, YAMAZAKI TOSHITSUGU, MISHIMA TOSHIAKI

  JAMSTEC深海研究 (23) 121 - 133 1340-7848 2003/12 [Not refereed][Not invited]
  
• High-resolution reconstruction of variation in aeolian dust (Kosa) deposition at ODP site 797, the Japan Sea, during the last 200 ka

  Irino, T., Tada, R.

  Global and Planetary Change 35 (1-2) 2003 [Refereed]
  
• High resolution records of organic carbon and its isotopes in Core MD01-2421 off central Japan, NW Pacific, during the last 145,000 years

  Ueshima, T., Yamamoto, M., Oba, T., Kuramoto, T., Minagawa, M., Irino, T.

  Geochimica Et Cosmochimica Acta 67 (18) 2003 [Refereed]
  
• Diatom record of the late Holocene in the Okhotsk Sea

  Koizumi, I., Shiga, K., Irino, T., Ikehara, M.

  Marine Micropaleontology 49 (1-2) 2003 [Refereed]
  
• 日本近海の長尺ピストンコアに見いだされたスープ状擾乱層

  山本, 正伸, 入野, 智久, 大場, 忠道, 村山, 雅史, 池原, 実, 小玉, 一人, 川幡, 穂高

  石油技術協会誌 石油技術協会 67 (6) 590 - 593 0370-9868 2002 [Refereed][Not invited]
  
• O-67 Temporal variations in aeolian dust flux and grain size based on elemental and grain size analyses of the Japan Sea sediments

  Irino T., Tada R., Matsui H., Nagashima K.

  Annual Meeting of the Geological Society of Japan 日本地質学会 2000 45 - 45 2000
• O-180 Strong grain size dependence of organic carbon content in the fine-grained sediments deposited under the influence of bottom current

  多田 隆治, 入野 智久, 佐藤 宗平, 長島 佳菜

  Annual Meeting of the Geological Society of Japan 日本地質学会 2000 101 - 101 2000
• Quantification of aeolian dust (Kosa) contribution to the Japan Sea sediments and its variation during the last 200 ky

  Irino, T., Tada, R.

  Geochemical Journal 34 (1) 2000 [Refereed]
  
• Millennial-scale compositional variations in late Quaternary sediments at site 1017, Southern California

  Tada, R., Sato, S., Irino, T., Matsui, H., Kennett, J. P.

  Proceedings of the Ocean Drilling Program: Scientific Results 167 2000 [Refereed]
  
• Late Quaternary textural change offshore of point conception, site 1017, central California margin

  Behl, R. J., Tada, R., Irino, T.

  Proceedings of the Ocean Drilling Program: Scientific Results 167 2000 [Refereed]
  
• Geochemical character of glacial to interglacial sediments at site 1017, southern Californian margin: Minor and trace elements

  Irino, T., Pedersen, T. F.

  Proceedings of the Ocean Drilling Program: Scientific Results 167 2000 [Refereed]
  
• Land-ocean linkages over orbital and millennial timescales recorded in late Quaternary sediments of the Japan Sea

  Tada, R., Irino, T., Koizumi, I.

  Paleoceanography 14 (2) 1999 [Refereed]
  
• 287 Paleo-environmental changes at ODP Site 1017, off California during the last 50,000 years.

  Sato S., Tada R., Irino T., Takayama H., Leg167 Shipboard Scientific Party

  Annual Meeting of the Geological Society of Japan 日本地質学会 1997 245 - 245 1997
• 225. Palaeoclimat ological significance of the Dans gaard Oscillation signal recorded in the Quat emary sediments of the Japan Sea

  TADA Ryuji, IRINO Tomohisa, KOIZUMI Itaru

  Annual Meeting of the Geological Society of Japan 日本地質学会 1995 199 - 199 1995
• 233. The flux variation of Kosa and the Japan Arc derived detritus at ODP Sites 797 and 798 in the Japan Sea during the last 200 ky

  IRINO Tomohisa, TADA Ryuji

  Annual Meeting of the Geological Society of Japan 日本地質学会 1995 203 - 203 1995
• Reconstruction of Miocene volcanic seamount and the sedimentation depth for siliceous shale of the Onnagawa Formation in the Fujisato area,northern Akita

  Yamamoto Shinji, Irino Tomohisa, Tada Ryuji, Iijima Azuma

  Journal of the Geological Society of Japan 日本地質学会 100 (8) 557 - 573 0016-7630 1994/08/15 [Refereed][Not invited]
  
• 158. The origin and flux varlation of the detritan components at ODP Sltes 797 and 798 in the Japan Sea during the late Quaternary

  IRINO Tomohisa, TADA Ryuji

  Annual Meeting of the Geological Society of Japan 日本地質学会 1994 127 - 127 1994
• 122 Depth of sedimentation for the Middle Miocene siliceous shale in the Fujisato area, Akita

  Yamamoto Shinji, Irino Tomohisa, Tada Ryuji, Iijima Azuma

  Annual Meeting of the Geological Society of Japan 日本地質学会 1990 255 - 255 1990

MISC

• Onset and evolution of millennial-scale variability of East Asian summer monsoon and its linkage with AMOC

  Tada Ryuji, Seki Arisa, Irino Tomohisa, Ikehara Ken, Itaki Takuya, Sagawa Takuya, Kubota Yoshimi, Sugisaki Saiko, Karasuda Akinori, Mitake Kaz, Ikeda Masayuki, Murayama Masafumi, Murray Richard W., Zarikian Carlos A., Scientist Expedition 346  Annual Meeting of the Geological Society of Japan  2019-  (0)  153  -153  2019  

• Close connection between East Asian monsoon and AMOC during the last 2.72 Ma

  Tada Ryuji, Ikeda Masayuki, murayama Masafumi, Murray Richard W, Alvarez-Zarikian Carlos A, Expedition 346 Scientists, Seki Arisa, Irino Tomohisa, Ikehara Ken, Itaki Takuya, Sagawa Takuya, Kubota Yoshimi, Sugisaki Saiko, Karasuda Akinori  Annual Meeting of the Geological Society of Japan  2018-  (0)  178  -178  2018  [Not refereed][Not invited]
   

  [Program canceled for a disaster] Program canceled for the 2018 Hokkaido Eastern Iburi earthquake. However, This abstract is quotable and viewable on PDF.
• Onset and evolution of centennial to millennial-scale variations of East Asian Summer Monsoon and their significance in global climatic changes

  Tada Ryuji, Lu Song, Seki Arisa, Kurokawa Shunsuke, Mitake Kaz, Murayama Masafumi, Irino Tomohisa, Karasuda Akinori, Ikehara Ken, Sagawa Takuya, Itaki Takuya, Sugisaki Saiko, Kubota Yoshimi, Ikeda Masayuki  Annual Meeting of the Geological Society of Japan  2017-  (0)  163  -163  2017  [Not refereed][Not invited]
   

  [Program canceled for typhoon] Program canceled for typhoon. However, This abstract is quotable and viewable on PDF.
• 大雪山地域の高層湿原泥炭の鉱物組成に基づく完新世における黄砂供給量の変動

  入野智久, 平井啓介, 関宰, HOOPER James, MARX Samuel K  日本地球惑星科学連合大会予稿集(Web)  2017-  ROMBUNNO.MIS23‐P13 (WEB ONLY)  2017  [Not refereed][Not invited]
  
• Controlling mechanism for mineral composition of suspended materials during a flood event at the Saru River, Hokkaido

  Irino Tomohisa, Nakata Satoshi, Ikehara Ken, Yamashita Youhei, Seki Osamu, Nagao Seiya  Annual Meeting of the Geological Society of Japan  2017-  (0)  062  2017  [Not refereed][Not invited]
  
• 日本海若狭湾沖における採泥結果~KR15‐10航海の概要報告~

  佐川拓也, 池原研, 中川毅, 入野智久, 高橋聡, 久保田好美, 松崎賢治, 鈴木克明, 小坂由紀子, LU Song, 多田賢弘, HOLBORNE Ann, HENDERSON Andrew, HUANG Huai‐Hsuan  ブルーアース要旨集  2016-  42  2016  [Not refereed][Not invited]
  
• Classification of dark and light layers in Quaternary sediments of the Japan Sea based on color and its application to identification of glacial- interglacial cycles

  Seki Arisa, Tada Ryuji, Irino Tomohisa, Karasuda Akinori, Murray Richard W., Alvarez Zarikian Carlos, Expedition 346 Scientists  Annual Meeting of the Geological Society of Japan  2015-  596  2015
• ターミナル海盆における2004年紀伊半島南東沖地震の地震性堆積物

  芦寿一郎, 大村亜希子, 奥津なつみ, 山口飛鳥, 入野智久, 村山雅史, 池原研, 中村恭之  日本地球惑星科学連合大会予稿集(Web)  2015-  ROMBUNNO.SCG64‐P11 (WEB ONLY)  2015  [Not refereed][Not invited]
  
• 終端堆積盆に記録された2004年紀伊半島南東沖地震時の地震性堆積物

  芦寿一郎, 大村亜希子, 山口飛鳥, 中村祐貴, 福地里菜, 入野智久, 村山雅史, 池原研, 中村恭之  日本地質学会学術大会講演要旨  121st-  86  2014/09/10  [Not refereed][Not invited]
  
• Temporal variation of very fine elemental carbon in sediments from the Lake Kushu in the Rebun Island during the last 3000 years

  Irino Tomohisa, Nakai Yoshie, Yamamoto Masanobu, Miyazaki Yuzo, Kawamura Kimitaka, Yamada Kazuyoshi, Yonenobu Hitoshi  Abstracts of Annual Meeting of the Geochemical Society of Japan  61-  (0)  287  -287  2014  [Not refereed][Not invited]
   

  遠距離輸送されるバイオマス燃焼起源物質の定量を目指して，堆積物中の極細粒元素状炭素（EC）量評価のために，Thermal optical transmittance法の応用を検討した．スクロース，フミン酸，フルボ酸，フラーレンのEC・有機炭素（OC）分析を行った結果，O2雰囲気，550℃-700℃に耐えるOCも存在することが分かったので，700℃-850℃で検出されるフラクションのみをECとして定義した．この方法で，礼文島・久種湖の湖底堆積物コアから選んだ試料を，2μmを境に粗粒および細粒に分画し，それぞれの粒度画分についてEC・OC分析を行った．その結果，粗粒・細粒画分中のEC・OC変動が異なる事が分かり、粗粒ECはローカルな，細粒ECはローカル，遠方両方のバイオマス燃焼起源である可能性が示唆された．ECの細粒/粗粒比変動は大陸規模でのバイオマス燃焼変動を反映する可能性がある．
• 東北沖浅海域における東北地方太平洋沖地震・津波に伴うイベント堆積物

  新井和乃, 成瀬元, 入野智久, 池原研, 笠谷貴史, 金松敏也, 野牧秀隆, 齋藤有, 横川美和, 泉典洋  ブルーアース要旨集  2013-  2013
• 471 Late Holocene human impact on vegetation changes around Beppu Bay in northeast Kyushu, southwest Japan based on the influx pollen data dated by a wiggle-matching

  Shimada Misaki, Takahara Hikaru, Kuwae Michinobu, Yamamoto Masanobu, Ikehara Ken, Irino Tomohisa, Takemura Keiji, Sagawa Takuya, Sakamoto Tatsuhiko, Ikehara Minoru, Takeoka Hidetaka  日本花粉学会会誌  58-  212  -213  2012/08/23
• 178 Detection and characterisation of millennial-scale vegetation and climate variability in Quaternary pollen records from East Asia -recent progress and future perspective

  Hayashi Ryoma, Takahara Hikaru, Igarashi Yaeko, Kumon Fujio, Liew Ping-Mei, Yamamoto Masanobu, Kawai Sayuri, Oba Tadamichi, Irino Tomohisa, Shichi Koji  日本花粉学会会誌  58-  81  -82  2012/08/23
• 東シナ海における古細菌および真正細菌群集の検出と鉛直分布

  片岡剛文, 入野智久, 山本正伸, 鈴木光次, 東正剛  日本海洋学会大会講演要旨集  2009-  185  2009/03/23  [Not refereed][Not invited]
  
• O-193 Changes in sea surface temperature in Okinawa Islands during the last 3,000 years

  Kitamura Akihisa, Yamamoto Nagisa, Irino Tomohisa, Kase Tomoki  日本地質学会学術大会講演要旨  114-  157  -157  2007/09/01
• S-60 Holocene 1500-year variation of the Kuroshio Current

  Yamamoto Masanobu, Isono Dai, Irino Tomohisa, Murayama Masafumi, Nakamura Toshio, Kawahata Hodaka  Annual Meeting of the Geological Society of Japan  2006-  (0)  31  -31  2006  [Not refereed][Not invited]
  
• 「みらい」MR02-K03 PC-2の珪藻化石群集に基づく過去20万年間の黒潮系暖水の変遷

  小泉 格, 入野 智久, 三島 稔明  海洋科学技術センタ-試験研究報告  (48)  1  -9  2003/12
• 「みらい」のMR01-K02 PC-1中の珪藻化石群集に基づく最終氷期末期--現間氷期における黒潮系暖水の変遷

  小泉 格, 入野 智久, 山本 浩文  海洋科学技術センタ-試験研究報告  (46)  39  -46  2002/11
• 北西太平洋域における完新世および最終氷期の風成塵フラックスと粒度 (総特集 海洋生物生産の加速と海洋大気)

  入野 智久  海洋  34-  (3)  156  -161  2002/03
• 「みらい」MR00-K05 PC-1及びPC-2の珪藻化石群集に基づく最終氷期末期〜現間氷期における黒潮系暖水の変遷

  小泉 格, 入野 智久, 山本 浩文  海洋科学技術センタ-試験研究報告  (44)  29  -40  2001/11
• 159. Establishment of the methods for the extraction of detrital components from diatomaceous sediments and the detrital grain size analysis

  Irino Tomohisa  日本地質学会学術大会講演要旨  100-  377  -377  1993/03/25

Books etc

• 海洋底科学の基礎

  日本地質学会「海洋底科学の基礎」編集委員会 (Contributor)
  共立出版 2016/09 (ISBN: 9784320047297) ix, 389p, 図版 [8] p
• 地球と宇宙の化学事典

  日本地球化学会 (Contributor)
  朝倉書店 2012/09 (ISBN: 9784254160574) xvi, 479p, 図版 [8] p
• 地球温暖化の科学

  (Contributor)
  北海道大学出版会 2007

Presentations

• Onset and evolution of millennial-scale variability of East Asian summer monsoon and its linkage with AMOC

  Tada Ryuji, Mitake Kaz, Ikeda Masayuki, Murayama Masafumi, Murray Richard W., Zarikian Carlos A., Scientist Expedition 346, Seki Arisa, Irino Tomohisa, Ikehara Ken, Itaki Takuya, Sagawa Takuya, Kubota Yoshimi, Sugisaki Saiko, Karasuda Akinori

  Annual Meeting of the Geological Society of Japan  2019  The Geological Society of Japan
   

• Progress report of the project to specify the location and magnitude of the Australasian tektite impact event

  Tada Ryuji, Okada Makoto, Suganuma Yusuke, Irino Tomohisa, Kubota Yoshimi, Tada Toshihiro, Carling Paul, Songtham Wichanet, Le Xuen Thuyen, Kayama Masahiro, Chang Yu, Kurosawa Kosuke, Tajika Eiichi

  Annual Meeting of the Geological Society of Japan  2019  The Geological Society of Japan
   

• Close connection between East Asian monsoon and AMOC during the last 2.72 Ma  [Not invited]

  Tada Ryuji, Ikeda Masayuki, murayama Masafumi, Murray Richard W, Alvarez-Zarikian Carlos A, Expedition 346 Scientists, Seki Arisa, Irino Tomohisa, Ikehara Ken, Itaki Takuya, Sagawa Takuya, Kubota Yoshimi, Sugisaki Saiko, Karasuda Akinori

  Annual Meeting of the Geological Society of Japan  2018  The Geological Society of Japan
   

  [Program canceled for a disaster] Program canceled for the 2018 Hokkaido Eastern Iburi earthquake. However, This abstract is quotable and viewable on PDF.
• Controlling mechanism for mineral composition of suspended materials during a flood event at the Saru River, Hokkaido  [Not invited]

  Irino Tomohisa, Nakata Satoshi, Ikehara Ken, Yamashita Youhei, Seki Osamu, Nagao Seiya

  Annual Meeting of the Geological Society of Japan  2017  The Geological Society of Japan
  
• 大雪山地域の高層湿原泥炭の鉱物組成に基づく完新世における黄砂供給量の変動  [Not invited]

  入野智久, 平井啓介, 関宰, HOOPER James, MARX Samuel K

  日本地球惑星科学連合大会予稿集(Web)  2017
• Onset and evolution of centennial to millennial-scale variations of East Asian Summer Monsoon and their significance in global climatic changes  [Not invited]

  Tada Ryuji, Lu Song, Seki Arisa, Kurokawa Shunsuke, Mitake Kaz, Murayama Masafumi, Irino Tomohisa, Karasuda Akinori, Ikehara Ken, Sagawa Takuya, Itaki Takuya, Sugisaki Saiko, Kubota Yoshimi, Ikeda Masayuki

  Annual Meeting of the Geological Society of Japan  2017  The Geological Society of Japan
   

  [Program canceled for typhoon] Program canceled for typhoon. However, This abstract is quotable and viewable on PDF.
• 日本海若狭湾沖における採泥結果~KR15‐10航海の概要報告~  [Not invited]

  佐川拓也, 池原研, 中川毅, 入野智久, 高橋聡, 久保田好美, 松崎賢治, 鈴木克明, 小坂由紀子, LU Song, 多田賢弘, HOLBORNE Ann, HENDERSON Andrew, HUANG Huai‐Hsuan

  ブルーアース要旨集  2016
• ターミナル海盆における2004年紀伊半島南東沖地震の地震性堆積物  [Not invited]

  芦寿一郎, 大村亜希子, 奥津なつみ, 山口飛鳥, 入野智久, 村山雅史, 池原研, 中村恭之

  日本地球惑星科学連合大会予稿集(Web)  2015
• 終端堆積盆に記録された2004年紀伊半島南東沖地震時の地震性堆積物  [Not invited]

  芦寿一郎, 大村亜希子, 山口飛鳥, 中村祐貴, 福地里菜, 入野智久, 村山雅史, 池原研, 中村恭之

  日本地質学会学術大会講演要旨  2014/09
• Temporal variation of very fine elemental carbon in sediments from the Lake Kushu in the Rebun Island during the last 3000 years  [Not invited]

  Irino Tomohisa, Nakai Yoshie, Yamamoto Masanobu, Miyazaki Yuzo, Kawamura Kimitaka, Yamada Kazuyoshi, Yonenobu Hitoshi

  Abstracts of Annual Meeting of the Geochemical Society of Japan  2014  GEOCHEMICAL SOCIETY OF JAPAN
   

  遠距離輸送されるバイオマス燃焼起源物質の定量を目指して，堆積物中の極細粒元素状炭素（EC）量評価のために，Thermal optical transmittance法の応用を検討した．スクロース，フミン酸，フルボ酸，フラーレンのEC・有機炭素（OC）分析を行った結果，O2雰囲気，550℃-700℃に耐えるOCも存在することが分かったので，700℃-850℃で検出されるフラクションのみをECとして定義した．この方法で，礼文島・久種湖の湖底堆積物コアから選んだ試料を，2μmを境に粗粒および細粒に分画し，それぞれの粒度画分についてEC・OC分析を行った．その結果，粗粒・細粒画分中のEC・OC変動が異なる事が分かり、粗粒ECはローカルな，細粒ECはローカル，遠方両方のバイオマス燃焼起源である可能性が示唆された．ECの細粒/粗粒比変動は大陸規模でのバイオマス燃焼変動を反映する可能性がある．
• 東シナ海における古細菌および真正細菌群集の検出と鉛直分布  [Not invited]

  片岡剛文, 入野智久, 山本正伸, 鈴木光次, 東正剛

  日本海洋学会大会講演要旨集  2009/03
• S-60 Holocene 1500-year variation of the Kuroshio Current  [Not invited]

  Yamamoto Masanobu, Isono Dai, Irino Tomohisa, Murayama Masafumi, Nakamura Toshio, Kawahata Hodaka

  Annual Meeting of the Geological Society of Japan  2006  The Geological Society of Japan
  

Association Memberships

• Paleosciences Society   Geological Society of Japan   Geochemical Society of Japan   Japan Association for Quaternary Research   Sedimentological Society of Japan   SEPM (Society for Sedimentary Geology)   American Geophysical Union   

Research Projects

• Elucidation of variation in marine primary production and biogeochemical linkages between land and ocean in North Pacific Ocean during the Neogene

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2022/04 -2026/03 

  Author : 沢田 健, 桑田 晃, 力石 嘉人, 入野 智久, 加藤 悠爾

   

  本研究では、深海掘削および陸上調査によって得られた新第三紀堆積物から、藻類および陸上植物の分子化石（バイオマーカー）、藻類微化石、生物源シリカを分析し、新生代の北太平洋におけるグローバルな海洋ー陸域間の生物地球化学的循環と生態系の連鎖（リンケージ）、環境気候システムとの関連性を解明する。海洋・陸域生態系が駆動する長時間スケールの物質循環システムの解明という観点から、海洋基礎生産と陸源有機物の海洋への輸送量の変動の体系的で定量性の高い復元を目指す。さらに、新しい古環境復元法を確立するため、新規の藻類バイオマーカーの探索とその解析法、陸上植物バイオマーカーの分子内同位体比解析法を開発する。2022年度における主な研究成果は次のとおりである。 1. 北部北太平洋アラスカ湾掘削コア（U1417）のバイオマーカー分析を行い、珪藻、ハプト藻、渦鞭毛藻、真正眼点藻などに由来するバイオマーカーを検出し、低分解能で大まかではあるが過去1000万年間の海洋基礎生産変動を復元した。また、ハプト藻由来の長鎖アルケノンおよび真正眼点藻由来の長鎖アルキルジオールを用いた古水温計によって海洋表層水温の変動を復元した。これらの水温の変動パターンは概ねよく一致し、全体的には中新世以降の全球的な寒冷化傾向を示すことがわかった。 2. 北海道中南部の日高町などに分布する中新統荷菜層における泥質堆積岩から、陸上セクションからは極稀な長鎖アルケノンが検出されることを発見した。そのアルケノン古水温計を用いて中期～後期中新世における体系的な海洋表層水温と海洋基礎生産の変動を復元した。 3. 陸源有機物において陸上植物だけでなく菌類のような生物のバイオマーカーにも着目し、特に地衣類の生体試料を用いて、新規のバイオマーカーを検討した。その結果、ファルネンなどのテルペノイドがそのバイオマーカーになり得ることを明らかにした。
• 海洋に存在する熱成有機物のミッシングソースの解明

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 2022/04 -2026/03 

  Author : 山下 洋平, 宮崎 雄三, 入野 智久
• Elucidation of the variation in marine primary production and the land-ocean biogeochemical linkage in North Pacific Ocean

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2022/04 -2026/03 

  Author : 沢田 健, 桑田 晃, 力石 嘉人, 入野 智久, 加藤 悠爾
• 霞ヶ浦における過去5000年間の季節を分けた洪水史復元

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 2022/04 -2026/03 

  Author : 山田 桂, 香月 興太, 多田 隆治, 入野 智久, 多田 賢弘, 鈴木 健太
• Reconstruction of atmospheric carbon dioxide concentration during the last 6 million years and the study of the interaction between atmospheric carbon dioxide and climate

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2019/06 -2024/03 

  Author : 山本 正伸, 吉森 正和, 阿部 彩子, 関 宰, 入野 智久

   

  温室効果は地球表層の温度を決める重要な要素である。大気中CO2濃度の連続的な測定は1957年以降であり、それ以前のCO2濃度はアイスコア気泡中のガス測定により復元されている（Luthi et al., 2008など）。しかし、アイスコアの最古の氷は80万年前のものであり、それ以前のCO2濃度の精密復元は行われていない。 本研究では、ベンガル湾の国際深海掘削科学計画（IODP）U1445地点の堆積物コアに含まれる長鎖脂肪酸の安定炭素同位体比（δ13CFA）を測定し、600万年前以降のCO2濃度を約1700年解像度で復元する。得られたデータにもとづき、鮮新世における気候感度を推定し、温暖期におけるCO2濃度と全球気温の関係を検討する。さらに、過去600万年間のCO2濃度と海洋深層水温度・気温・氷床量変動との関係から、CO2濃度変動の原因を考察し、CO2と気候の相互作用を解明する。 脂肪酸同位体比測定は全3200試料が終了した。過去80万年間のCO2濃度復元値は、アイスコアのCO2濃度およびU1446地点でのCO2濃度復元値と良い一致を示し、当研究で用いているCO2濃度復元手法をU1445地点に適用することが妥当であることが確かめられた。国際深海掘削科学計画（IODP）U1445地点での船上分析により得られた生層序と非破壊分析の結果に基づき仮の年代モデルを作成した。 U1446地点で得られたCO2濃度変動記録と過去150万年間の降水量変動を比較し、δ13CFA変動の2-10%は降水量変動により、 78%がCO2濃度変動でより説明可能であることを示した。CO2濃度と降水量の変動がインド東部のC3/C4植生に与える影響を植生モデルを用いて検討した。このモデルの結果からも、δ13CFA変動は基本的にCO2変動を反映していることが明らかになった。
• Refinement of biomarker-based paleovegetation analysis, and its application to reconstruction of the paleovegetational variation in the northern Japan over the past 5 million years

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2018/04 -2021/03 

  Author : Sawada Ken

   

  The objective of this study is to reconstruct variations in paleovegetation and terrestrial paleoenvironment by analyses of terrestrial plant-derived biomarkers and pollen/spore in sediment cores from Japan Sea off Hokkaido (U1422 and U1423 cores) collected by the International Ocean Drilling Program (IODP). We reconstructed the paleovegetation variations during ca. 4.3 million years and centurial-scale variations during ca. 700 kiloyears in U1423 and U1422 sites, respectively. The paleovegetation variations reconstructed by the coniferous diterpenoids and the triterpenoids derived by broad-leaved tree are synchronous to the global climatic variations such as warm/cool conditions with glacial/interglacial or centurial scales, elucidating paleoclimatic system variations related to monsoonal system in the northern Japan Sea by combined analyses of organic molecules and pollens.
• Reconstruction of the Pacific Decadal Oscillation during the last 8000 years by the analysis of Beppu Bay sediment cores

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2016/04 -2019/03 

  Author : Yamamoto Masanobu

   

  We analyzed paleotemperature and fish scale abundance in sediments from two 20 m-long cores retrived from Beppu Bay, Kushu, Japan and generated a four-year resolution records of the Pacific Decadal Oscillation and regime shifts during the last 8000 years. The result indicates that the periods of dominant 50-year and 200-year cycles were exchanged on muti-centennial scale, suggesting a modulation of the Pacific Decadal Oscillation by external forcing, most likely, both solar and volcanic forcings.
• Centennial to millennial-scale variability of East Asian Monsoon: Onset timing, temporal changes, and their controlling factors

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2016/04 -2019/03 

  Author : Tada Ryuji, SEKI Arisa, WANG Ke, MITAKE Kaz, MATSUZAKI Kenji, KUROKAWA Shunsuke

   

  Variations of Marine Organic Carbon (MOC) content in the dark and light hemipelagic sediments from the deeper part of the Japan Sea reflect variability of East Asian Summer Monsoon (EASM) precipitation through nutrient influx through the Tsushima Strait and consequent enhancement of surface productivity in the sea. We used IODP cores from 3 depth transect sites in the Japan Sea and reconstructed temporal changes in EASM intensity during the last 3 Ma based on high-resolution analyses of the cores. The result revealed onset of millennial-scale large and abrupt changes of EASM intensity at 1.31 Ma, temporal changes in their periodicity and amplitude was closely related with the ice volume and its growth rate, and changes in westerly jet path seem to play a critical role in propagation of the signal from high-latitude North Atlantic.
• Accuracy improvement of earthquake history of the Nankai Trough by sediment records from terminal basins

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2015/04 -2018/03 

  Author : Ashi Juichiro, IRINO Tomohisa, YAMAGUCHI Asuka, OMURA Akiko

   

  We conducted shallow subbottom profiling survey and sediment core sampling in the Nankai forearc region to know the earthquake history from off Tokai to off Hyuga. A subbottom profiler on a remotely operated vehicle successfully obtained high-resolution shallow subseafloor structures from the trench landward slope to the forearc basin, and found active faults and on-going tilting off Cape Muroto and off Hyuga. Sedimentological study revealed rework and redeposition processes of surface sediments by earthquake shaking and suggested that the thickness of the redeposited layer could correlate with the depth of the reworked unit of the source formation.
• Reconstruction of variations in paleovegetation during the Quaternary by analysis of plant-derived organic molecule in the deep sea drilling sediment cores from the Atlantic Ocean and Japan Sea

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2014/04 -2017/03 

  Author : Sawada Ken, IGARASHI Yaeko

   

  The objective of this study is to reconstruct variations in paleovegetation and terrestrial paleoenvironment by analyses of terrestrial plant-derived biomarkers and pollen/spore in sediment cores from northeastern Atlantic Ocean off the Iberian Peninsula (U1385) and the Japan Sea off the southwestern coast of Hokkaido (U1423) collected by the International Ocean Drilling Program (IODP). We reconstructed the paleovegetation variations during 4.3 million years and centurial-scale variations during the marine isotope stages (MIS) 12 - 10 in U1423 and U1385 sites, respectively. In particular, the paleovegetation variations reconstructed by the indicators for diterpenoids derived from Taxodiaceae/Cupressaceae and Pinaceae are synchronous to the global climatic variations such as warm/cool conditions with glacial/interglacial or centurial scales, confirming high applicability of the terpenoid proxy for reconstructing paleovegetation from deep sea sediment.
• Understanding the mechanisms controlling the environmental dynamics of radionuclides released from the Fukushima Daiichi Nuclear Power Plant in the ocean.

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2012/06 -2017/03 

  Author : YAMADA MASATOSHI, UEMATSU Mitsuo, KAWAKAMI Hajime, IKEHARA Ken, IRINO Tomohisa, TAKAHATA Naoto, MASUMOTO Norio, ISOBE Atsuhiko, KIDA Shinichiro, TSUBONO Takaki, MISUMI Kazuhiro, INOMATA Yayoi, KAERIYAMA Hideki, KUSAKABE Masashi, YANG Guosheng, NAKANO Toshiya, POVINEC Pavel, BUESSELER Ken, HULT Mikael, NIES Hartmut

   

  The Fukushima Dai-ichi Nuclear Power Plant(FNPP1) accident has resulted in a substantial release of radionuclides to the atmosphere and ocean, and has caused extensive contamination of the environment. The objectives of this study were to collect seawaters, marine sediments and settling particles in Japanese coast and North Pacific Ocean and to understand the condition and factor of the radionuclide distribution therein. FNPP1-derived radiocesium spread eastward in the surface water across the mid-latitude North Pacific with a speed of 7 km/day and it had been transported into the ocean interior due to formation/subduction of subtropical mode water and central mode water. The release of Pu isotopes from the FNPP1 accident to the marine environment was negligible. The FNPP1-derived radiocesium was detected in settling particles collected at 4810 m in early April 2011 at station in the subarctic gyre and it was quickly transported to the deep sea in the western North Pacific.
• High resolution reconstruction of Holocene sea surface temperature in the Southern Ocean and the Arctic Ocean

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2013/04 -2016/03 

  Author : Yamamoto Masanobu, IRINO Tomohisa, YOKOYAMA Yusuke

   

  TEX86 analysis indicated that sea surface temperature (SST) decreased from 12,000 years ago to 3,000 years ago and increased afterward off Wilkes Land in the Southern Ocean. In the Chukchi Sea of the Arctic, SST increased since 9,000 years ago. Both areas showed significant millennial-scale SST variability. In the Chukchi Sea core, the chlorite/illite ratio showed higher values in the middle Holocene, suggesting the intensified Bering Strait inflow. The Quartz/feldspar ratios showed a decreasing trend, suggesting a decline of the Beaufort Gyre circulation since 9,000 years ago.
• Changes in hydrological cycle in East Asia during the Holocene and their implication for Global Monsoon

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2011/04 -2016/03 

  Author : TADA Ryuji, NAKAGAWA Takeshi, ZHENG HONGBO

   

  Provenance changes of suspended sediments of the Yangtze River during the last 7 k.y. revealed millennial-scale changes in East Asian summer monsoon (EASM) precipitation front between NW and SE parts of the Yangtze drainage with SE-ward retreat during 5.4-3.5 and 1.9-0.2 k.y. These shifts are associated with southward shifts of the westerly jet(WJ) during the same periods deduced from provenance changes of eolian dust in the Japan Sea sediments, supporting the idea that northern limit of the EASM front is controlled by the position of the WJ. Floods record of Lake Suigetsu implies frequent storms during these periods suggesting shifts of the storm track. Comparison with Southern Hemisphere WJ position revealed symmetric movement of WJ in both hemispheres with respect to the equator, suggesting expansion and shrinkage of the Hadley circulations seem the cause of these changes. It is possible the solar activity is the ultimate forcing but further study is needed.
• Development of new carbonate dissolution index by X-ray Tomography and geochemical proxies

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2012/04 -2015/03 

  Author : KIMOTO Katsunori, SASAKI Osamu, IRINO Tomohisa, WAKITA Masahide

   

  We developed a novel method to know the shell density of calcareous zooplankton (foraminiera) by using Micro X-ray Computing Tomography (MXCT) successfully. We found that shell density of individual planktic foraminifers which were recovered by the sediment trap deployed at Stn. K2 (47N, 160E), North Pacific had remarkably changed seasonally. In particular, shell degradation progressed in winter season from December to April. According to observations of seawater chemistry, shell density changes might be closely associated with carbonate systems and related physicochemical parameters: vertical mixing, pH, TCO2 and Omega. Geochemical proxy (strontium-calcium ratio, Sr/Ca) of individual foraminiferal shell indicated strong correlation with shell density, and it suggests that Sr/Ca of foraminiferal shells has potential to be a quantitative tracer of carbonate dissolution. These result should contribute to understand material cycles of ocean and biogeochemical cycles.
• Analysis of ecosystem function of taiga in eastern Siberia

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2009 -2012 

  Author : SUGIMOTO Atsuko, IRINO Tomohisa, OHOTE Nobuhito, TOKUCHI Naoko, IWAHANA Go, KODAMA Yuuji, YAMASHITA Yohei, ISHII Yoshiyuki, OHOTA Takeshi, UZUKI Rikie, YONENOBU Hitoshi

   

  Field observations were carried out on water, carbon, and nitrogen cycles in taiga and taiga-tundra boundary in eastern Siberia. Soil moisture water equivalent at taiga forest study site was reconstructed for pas 100 years from tree-ring 13C of larch. Our observational results showed that the wet condition in 2006-2007 was extreme event, and runoff from the region to Lena river was generated for a whole year during this period. N dynamics was also observed in larch forest. Soil inorganic N pool size showed large seasonality depending on the soil temperature.
• Development of proxy for oceanic carbonate using Micro-X-ray CT technique

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2009 -2011 

  Author : KIMOTO Katsunori, SASAKI Osamu, IRINO Tomohisa

   

  Quantitative evaluation methods of dissolution for marine carbonates(foraminifera) using Micro-focus X-ray Computing Tomography(MXCT) has developed. Quantity of carbonate dissolution is expressed by total CT value as shell volume, and mean CT value as shell density. Availability and usefulness of this method was confirmed for natural and laboratory samples.
• Reconstruction of changes in the atmospheric convection activity in the tropical Pacific Ocean during the last 150,000 years using hydrogen isotopes of biomarkers

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2007 -2011 

  Author : YAMAMOTO Masanobu, IRINO Tomohisa, SUGIMOTO Atsuko, OKINO Tatsufumi

   

  We reconstructed the atmospheric convection activity in the tropical Pacific by analyzing biomarkers in marine cores retrieved from five locations in the tropical Pacific. Paleotemperature records demonstrated that the cold tongue shrunk, the western Pacific warm pool expanded, and zonal temperature gradient was relaxed during the last deglaciation. A deuterium record of fatty acids from the southern South China Sea disagrees with a published stalagmite record from northern Borneo. The latter is consistent with paleotemperature records, suggesting that zonal temperature gradient and the position of convection center has varied in response to precession.
• 利尻島および日本海北部海域に降下するシベリア森林火災起源物質の時代変化

  Date (from‐to) : 2009
• Temporal variation of charcoal deposition originated from Siberian forest fire in the Rishiri Island and the northern Japan Sea

  Date (from‐to) : 2009
• Reconstruction of paleoceanographic variations of Kuroshio over the past 7,000 years from oxygen isotope ratio of the micro-bivalvia ound in a submarine cave

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2007 -2008 

  Author : KITAMURA Akihisa, IRINO Tomohisa, KASE Tomoki

   

  海底洞窟から採取した堆積物コア試料に含まれる160個体の微小二枚貝の酸素同位体比を測定した. その結果, 現在よりもかなり寒冷・乾燥化した冬期が, 6,300年前, 5,550年前. 5,200年前に起きており, それらの期間は太陽活動の弱体期にあたる. このことから, 日本南方域の気候は, 太陽活動の影響を受けることが分かった.
• Research of characteristics of riverine suspended particles released by heavy rain and their effects on coastal ecosystem

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2006 -2008 

  Author : NAGAO Seiya, YAMAMOTO Masanobu, IRINO Tomohisa, HUJITAKE Nobuhide, ARAMAKI Takahumi

   

  石狩川河川水の懸濁態有機物の放射性炭素のδΔ14C値は年間を通じて大きな変動を示し、雪融けと降雨時には古い有機物が移動していることが明らかとなった。その変動幅は下流域<中流域<河口域<上流域の順であり、河川に供給される懸濁態の有機物は、河川流域環境や水の供給経路等の特徴と関連して変動することが考えられる。これらの結果から、沿岸域への影響評価には、雪融けと降雨時の粒子の供給量と供給機構の重要性が示唆された。
• The 2003 Hokkaido Hidaka flood : sedimentary processes in the open ocean and influence to sea bottom environments

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2005 -2007 

  Author : IKEHARA Ken, KATAYAMA Hajime, NODA Atsushi, TUZINO Taqumi, IRINO Tomohisa, OMURA Akiko

   

  Floods supply large amounts of terrigenous materials to marine environments that affects sea bottom environments and strata formation. Quick deposition of large amount of sediments on sea floor may influence to sea floor environments. Because of few marine geological and sedimentological surveys have been conducted immediately after floods, behavior of flood sediments in marine environments and sedimentary processes are not well understood. In August 2003, heavy rain associated with by the typhoon 200310 caused flooding and landslides in Hidaka area, Hokkaido large amount of sand and mud were transported by rivers to ocean. Our survey indicated the two modes of flood mud deposition on the shelf. One is transportation by density (hyperpycnal) flows. Long distance transport across shelf was available by this mechanism. Another is diverse by hypopycnal surface plume. Flood mud was deposited near the river mouth by this system. Inner shelf submarine topography controls such a transportation mode. Taking into account of flood mud deposition on the outer shelf to deep-sea basin floor, the larger amount of terrigenous materials than those previously estimated from river observations were supplied to ocean by this flood. There results verify the importance of the hyperpycnal flow for long-distance transport of the terrigeouns materials to the deep-sea, and flood plays an important role on material supply to deep-sea.
• Evaluation of nutrient impact from river to coastal biogeochemical systems as an aspect from material transport processes

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2004 -2007 

  Author : MINAGAWA Masao, NAGAO Seiya, IRINO Tomohisa, KATO Yoshisa, NARITA Hisashi, MURAYAMA Masafumi

   

  We have investigated biogeochemical role of river runoff at several locations in Hokkaido, Central Honshu and Shikoku districts and have evaluated the contribution of these river water for the coastal biological production that is dealing with the marine carbon cycling. Based on geochemical observations including nutrient and isotopic analyses at Tokachi river, Abe river, Niyodo river, and Shimanto river, we found following results. (1) Nutrient loadings from Tokachi river were estimated as 1.3 and 0.009 mol/m^2/yr for DIN, and DIP, respectively. (2) These nutrient discharge can have dealings with 8.4 molC/m^2/yr as photosynthesis and may benefit for diatom production by their N/P and Si/N ratios. (3) Sporadic events with heavy precipitation can supply large effect mainly for nitrogen which provides potentially corresponding to 8% DIN supply of mean annual transport flux. (4) River discharge in the snow melting season would supply 30 to 40% of nutrient needed for coastal biological production, on the other hand particulate organic carbon make for less than one tenth of carbon fixation and less than a half of PON nitrogen. (5) The first class rivers in Shizuoka prefecture tend to have relatively lower nitrogen content ranging from 27 to 98 μM, but those in the second class rivers showed higher concentrations ranging from 82 to 504 mM and even wide variations. The phosphate and silicate concentrations are ranging from 0.21 to 9.2 μM and from 109 to 413 μM, respectively, reflecting difference of local environmental conditions such as water shed area, land utilization pattern and degree of civilizations.
• Improvement of paleo-SST and SSS reconstruction based on precise estimation of secondary calcification and dissolution of planktonic foraminifer test

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2005 -2006 

  Author : IRINO Tomohisa

   

  Calcite test of planktonic foraminifer produced in surface ocean sinks in the water column after its death, deposits on the seafloor, and buried in the sediment. During these process, the weight of test decreases by dissolution and increases by secondary calcification. Weight loss of calcite test has been regarded as a good proxy for carbonate dissolution, however, estimation of secondary calcification is also necessary to know a true weight loss. Since secondary calcification occurs in the deep ocean, paleo-sea surface temperature (SST) and salinity (SSS) information recorded in isotope and chemical composition of test calcite would be also biased. In order to establish the method to estimate true weight loss from and addition on initial calcite test of planktonic foraminifer, weight and oxygen / carbon isotopes analyses were conducted on 50-70 individula foraminifer tests obtained from surface water, water column, and sediments in the western North Pacific. As a result of evaluation for Globigerinoides sacculifer tests, 1) G. sac produce their tests in the surface water and attach gametogenic calcite in < 400 m water depth 2) Gametogenic calcite increases test weight by~20% 3) Dissolution slightly occur during sinking process but secondary calcification does not occur in the water column 4) Significant dissolution occur on the sea floor followed by secondary calcification during burial process Positive correlation of oxygen isotope and weight suggests a strong influence of secondary calcification to the isotope information kept in foraminifer tests. Dissolution process of formaminifer test is characterized by thinning of their wall. Strong dissolution finally break the wall of tests, which leads to a positive skewness of weight distribution of perfect foraminifer tests, because imperfect (broken) test is not counted for weight measurement. It is discovered during this research that the skewness of weight distribution is a good semi-quantitative estimator of carbonate dissolution which is independent of secondary calcification. This fact enables us to estimate a true loss of primary calcite and addition of secondary calcite from the sediment core samples, and the objective of this study to improve the paleo-SST / SSS proxy using foraminifer tests is archieved.
• High resolution reconstruction of hydrological cycle in the East Asia during the last deglaciation using terrestrial biomarkers

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2004 -2006 

  Author : YAMAMOTO Masanobu, IRINO Tomohisa, TADA Ryuji, IKEHARA Minoru, OBA Tadamichi

   

  This study aims at examining the role of El Nino-Southern Oscillation in last deglacial warming and hydrological changes by reconstructing the latitudinal gradient of precipitation along the East Asian margin during the last deglaciation. For this purpose, we analyzed terrestrial biomarkers in marine cores from five different locations from the tropical to subarctic regions. Variations in lignin, terrestrial biomarkers and pollen compositions and biomarker-specific deuterium/hydrogen ratio indicated a dry climate in the regions north of 30 degrees north and an increase of precipitation at the site of 8 degrees north during the last deglaciation. This enhanced latitudinal gradient of precipitation was presumably caused by the combination of El Nino-like atmospheric pattern in the North Pacific and the intensified tropical convection. Other findings are as follows. The winter Aleutian Low was intensified during the last two deglaciations. Winter monsoon was stronger during the last deglaciation. The Holocene 1500-year oscillation was found in the sea surface temperature record from the Japan margin.
• 有孔虫の殻内有機物を用いた地質時代の大気CO_2分圧プロキシの開発

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 2004 -2005 

  Author : 長谷川 卓, 入野 智久, 田崎 和江, 森下 知晃, 池原 実

   

  本年度は,有孔虫の殻に閉じ込められた有機物の含有量について,現生底生有孔虫,化石底生有孔虫(膠着質,石灰質),現生浮遊性有孔虫について分析を行った結果,約0.1-0.4%の含有量を持っていることが明らかになった.特に,浮遊性有孔虫ではその含有量の個体や種による差は小さいことがわかり,同位体分析のための適切な試料量が容易に推定できるようになった.そこに至るまでの過程で,様々な溶媒を用いたり,ふるいを自作するなどして効率的な準備方法を開発した.これらの作業は金沢大学で行った. これらの手法がほぼ確立したことを受け,実際に北海道大学地球環境科学研究院に設置の微量炭素の同位体比分析が可能な装置を用いて個別の種の浮遊性有孔虫(赤道太平洋の表層堆積物に含まれる現生浮遊性有孔虫)の殻構造内部に含まれる有機物の炭素同位体比を測定した(18年2月,3月).1個体の殻の重量が異なるため,分析に用いた有孔虫の個体数は種によって異なるが,Globorotalia menardiiでは100個体を用いて分析を行い,3回測定を繰り返すことができる程度の二酸化炭素ガスを得ることができた.Globigerinoides sacculiferでは400個体を用いることでほぼ同量のガスを得た.個別に処理したG.menardiiの4試料ではいずれも-24.35±0.3‰の範囲であった。このように開発した処理法は炭素同位体比の再現性が高いことが示すことができた.G.sacculiferでは1試料で-22.9‰,Globorotalia tumidaでは2試料から-23.72‰および-24.12%を得た.このように,種が異なっても同位体比値が大きく異なることがない. 本研究の結果,有孔虫の殻体構造内に閉じ込められた有機炭素の同位体比分析の手法が確立した.今後,確立した手法を用いてデータを増やすことで,表層種と温度躍層種に系統的な差があるのかどうか,などが議論できる.また,実用面に関しては,限定した種を用いて有機炭素同位体比の経時変化を調べ,その炭酸塩炭素の同位体比との差を取り,その差が経時的にどのような変化を示すのか,を調査する次のステップに研究を進める段階に達した。
• Study on Accumulation and Transportation of Refractory Organic Materials in Terrestrial Area

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2003 -2005 

  Author : NAGAO Seiya, YAMAMOTO Masanobu, FUJITAKE Nobuhide, IRINO Tomohisa, KODAMA Hiroki

   

  An important part of global organic carbon cycle is the flux of terrestrial organic carbon from the continents to the oceans. The potential importance of coastal systems in global and regional organic budgets is still unclear because of the inherent complexity and variability of rivers, estuaries and coastal zones. Therefore, it is important to understand the organic matter cycling in estuaries and coastal systems, especially characteristics and dynamics of river DOM and POM. But the DOM and POM is not homogeneous in terms of size or chemical characteristics so that we can't evaluate the linkage of terrestrial and coastal environments. The objective of this study is to understand the transport behavior of dissolved and particulate organic matter from terrestrial region to ocean. This study used carbon isotopic ratios (Δ^<14>C and δ^<13>C values) as tracers of organic carbon because the simultaneous use of these values adds a second dimension to isotopic studies of carbon cycling in surface aquatic environments. Refractory organic materials, humic substances, were isolated from the river waters in Scotland, Ukraine, Japan and Indonesia by the XAD extraction. The Δ^<14>C values of dissolved humic substances ranged from -316‰ to +209‰, indicating spatial and temporal distribution. To understand transport of POM in river systems, we selected three river systems (Tokachi, Ishikari and Kuji River systems) with different watershed conditions and carried out the observation at a fixed point in each river. The Δ^<14>C values range from -111 to -286‰ for the Tokachi River in northeast Hokkaido, -103〜-364‰ for the Ishikari River in southeast Hokkaido and -18.7〜-94.4‰ for the Kuji River in Kanto area in Japan. The paired Δ^<14>C vs. δ^<13>C distributions vary with rivers and seasons. These results suggest that the difference in paired Δ^<14>C vs. δ^<13>C distributions may reflect the water discharge and watershed environments.
• 河川懸濁粒子の量および組成観測に基づく河川流出量変動の海洋への影響の解明

  Date (from‐to) : 2004
• Biogeochemical impact on marine environment from river discharge based on observation of river suspended materials

  Date (from‐to) : 2004
• Chemical pproxy parametarization for evaluating prehistoric human activities.

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2001 -2003 

  Author : MINAGAWA Masao, IRINO Tomohisa, NAGAO Seiya, YAMAMOTO Masanobu, MATSUI Akira, NISHIMOTO Tohohiro

   

  The purpose of this project is to prepare analytical procedures to identify a chemical evidence of human activities and to develop a chemical method to discriminate human remains from natural substances found in archeological sites. We focused organic compounds and stable isotope compositions, as both parameters are expected to characterize human agricultural activity and domestication of wild animals. Soil samples were collected from some archaeological sites, modern agricultural fields and natural fields. Some compounds in lipid fraction were extracted for identifying molecular composition by gas chromatography-mass spectrometer analysis. Stable carbon and nitrogen isotopes ratios were simultaneously studied to characterize biogeochemical perturbation of soil organic matter under taking agricultural activity. Bone collagen isotope analyses were also applied to discriminate domestication of Sus scrofa from wild boar populations. Soil organic matter analysis in modern agricultural field revealed that δ^<13>C and δ^<15>N of soil organic matter can be a useful proxy indicating C4 plants cultivation and consequent human perturbation of the soil microbe. Based on this result, soil samples from Bibi excavation site, a middle-Jomon sites in Chitose city, Hokkaido, evidences that there should be some kind treatment by prehistoric human at least 4,000 years, ago. In addition to this evidence molecular evidence by deoxycholic acids, a component of human bile, for soild lipid fraction also suggested likely usage of human leftover as fertilizer or toilet. Same analysis was applied to soil samples from burial site, Kamifukushima Nakamachi in Gunma prefecture, a lost village by a volcanic eruption in Edo era. Deoxycholic acid was detected closely in the soil from both a farm and manure sink in a farmer house, indicating that such molecules can be a promising proxy indicating manure treatment. Carbon and nitrogen isotope ratios of bone collagen were used to identify a individual of pigs from wild boar. We revealed that early domestication of boar could produce pigs having unusual isotopic patterns due to artificial feeding by human being, then it ca be useful proxy to detect early evidence of pig feeding.
• High-resolution reconstruction of environmental change off the east coast of Japan since the last 50,000 years reconded in a marine sediment core.

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2001 -2003 

  Author : OBA Tadamichi, YAMAMOTO Masanobu, NAGAO Seiya, OKADA Hisatake, NARITA Hisashi, IRINO Tomohisa

   

  The northwest Pacific, where the cold Oyashio and the warm Kuroshio Currents meet each other today, is the most sensitive region in the North Pacific for monitoring the migration of the western boundary corrects in response to the past climatic change. A long core (45.82 m length) was recovered from 2,224 m water depths off the central Japan during the IMAGES cruise in 2001. A multi-disciplinary study was carried out on the core by analyzing the following research items : color, grain size, mineral composition, paleomagnetism, δ^<18>O, δ^<13>C Opal, CaCO_3, species of diatoms, coccolithophorids, radiolaria, planktonic foraminifera and benthic foraminifera, CaCO_3 preservation, Uk37', TOC, C/N, δ^<13>C_, δ^<15>N_, biomakers and pollen. The following main results ware obtained. The δ^<18>O curve of G.bulloides is similar to the standard oxygen isotope curve, suggesting continuous deposition over the last 145 ka. All warm water indices yielded by the four microfossil assemblages (diatoms, coccolith, radiolaria, planktonic foraminifera) show temperature decreases during the MIS 2 and 6, and increases during the MIS 5, although their correlation coefficients with each other are not always high (between 0.5 and 0,6). The Alkenon-derived temperature (19℃) at the core top agrees with the mean annual SST at present time in this region. The SST at the end of the MIS 2 was 13℃, which is seen today about 4.5 degree latitude north than the core site. Similar migrations in SST are inferred from the coiling ratio of N.pachyderma. The C/N ratio, δ^<13>C_ and δ^<15>N_ indicate that the TOC is mainly of marine origin, although terrestrial origin slightly increases during the MIS 6. The curve of the warm pollen index is similar to the δ^<18>O curve of G.bulloides, except for the MIS 6 and 5e when the land temperature changes inferred from the pollen curve precede the δ^<18>O curve.
• 海底細粒堆積物の粒度・鉱物・化学組成にもとづく供給源と運搬過程の解明

  Date (from‐to) : 2000
• Provenance and transport process of fine grained marine sediments based on grain size, mineral, and chemical composition

  Date (from‐to) : 2000
• 日本海・北西太平洋深海底堆積物への黄砂及び島弧起源砕屑物フラックスの時空変動復元

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 1998 -1998 

  Author : 入野 智久