*Japanese articles are not listed on this page. 

Peer-Reviewed Papers

2024 ｜2023 ｜2022 ｜2021 ｜2020 ｜ 2019 ｜ 2018 ｜ 2017 ｜ 2016 ｜ 2015 ｜ 2014 ｜ 2013 ｜ 2012 ｜ 2011 ｜ 2010 ｜ 2009 ｜ 2008 ｜ 2007 ｜ 2006 ｜ 2005 ｜ 2004 ｜ 2003 ｜ 2002 ｜ 2001 ｜ 2000 ｜ 1994-1999

2024

• Kochi, T., Yoshimura, T., Ogawa, N.O., Ohkouchi, N., Kobayashi, Y., and Kuroda, J. (2024) Carbonate Associated Sulfate Extraction Method Using Weakly Acidic Cation Exchange Resins. Geostandards and Geoanalytical Research, 48(1), 77-89. doi:10.1111/ggr.12536. [Abstract]
• Koga, T., Takano, Y., Oba, Y., Naraoka, H., and Ohkouchi, N. (2024) Abundant extraterrestrial purine nucleobases in the Murchison meteorite: Implications for a unified mechanism for purine synthesis in carbonaceous chondrite parent bodies. Geochimica et Cosmochimica Acta, 365, 253-265. doi:10.1016/j.gca.2023.10.024. [Abstract]
• Nitzsche, K.N., Ishikawa, N.F., Yoshimura, T., Kajita, H., Kawahata, H., Ogawa, N.O., Suga, H., and Ohkouchi, N. (2024) Historical trend of polycyclic aromatic hydrocarbons in a sediment core from Osaka Bay during the Meghalayan. The Holocene, in press. doi:10.1177/09596836241236320. [Abstract]
• Sugahara, H., Yoshimura, T., Tamenori, Y., Takano, Y., Ogawa, N.O., Chikaraishi, Y., and Ohkouchi, N. (2024) Nitrogen K-edge X-ray adsorption near-edge structure spectroscopy of chemically adsorbed ammonia gas on clay minerals and the 15N/14N-nitrogen isotopic fractionation. Analytical Sciences, in press. doi:10.1007/s44211-023-00503-5. [Open Access]
• Yoshikawa, C., Shigemitsu, M., Yamamoto, A., Oka, A., and Ohkouchi, N. (2024) A nitrogen isoscape of phytoplankton in the western North Pacific created with a marine nitrogen isotope model. Frontiers in Marine Science, 11: 1294608. doi:10.3389/fmars.2024.1294608. [Open Access]

2023

• Hashiguchi, M., Aoki, D., Fukushima, K., Naraoka, H., Takano, Y., Dworkin, J.P., Dworkin, K.E., Aponte, J.C., Elsila, J.E., Eiler, J.M., Furukawa, Y., Furusho, A., Glavin, D.P., Graham, H.V., Hamase, K., Hertkorn, N., Isa, J., Koga, T., McLain, H.L., Mita, H., Oba, Y., Ogawa, N.O., Ohkouchi, N., Orthous-Daunay, F.-R., Parker, E.T., Ruf, A., Sakai, S., Schmitt-Kopplin, P., Sugahara, H., Thissen, R., Vuitton, V., Wolters, C., Yoshimura, T., Yurimoto, H., Nakamura, T., Noguchi, T., Okazaki, R., Yabuta, H., Sakamoto, K., Tachibana, S., Yada, T., Nishimura, M., Nakato, A., Miyazaki, A., Yogata, K., Abe, M., Usui, T., Yoshikawa, M., Saiki, T., Tanaka, S., Terui, F., Nakazawa, S., Watanabe, S.-i., and Tsuda, Y. (2023) The spatial distribution of soluble organic matter and their relationship to minerals in the asteroid (162173) Ryugu. Earth, Planets and Space, 75: 73. doi:10.1186/s40623-023-01792-w. [Open Access]
• Ishikawa, N.F., Tadokoro, K., Matsubayashi, J., and Ohkouchi, N. (2023) Biomass Pyramids of Marine Mesozooplankton Communities as Inferred From Their Integrated Trophic Positions. Ecosystems, 26, 217-231. doi:10.1007/s10021-022-00753-w. [Abstract]
• Kajita, H., Isaji, Y., Kato, R., Nishikura, Y., Murayama, M., Ohkouchi, N., Yang, S., Zheng, H., Wang, K., Nakanishi, T., Sasaki, T., Maeda, A., Suzuki, A., Yamanaka, T., and Kawahata, H. (2023) Climatic change around the 4.2 ka event in coastal areas of the East China Sea and its potential influence on prehistoric Japanese people. Palaeogeography, Palaeoclimatology, Palaeoecology, 609:111310. doi:10.1016/j.palaeo.2022.111310. [Open Access]
• Kaku, Y., Isobe, N., Ogawa, N.O., Ohkouchi, N., Ikuta, T., Saito, T., and Fujisawa, S. (2023) Chitin nanofiber-coated biodegradable polymer microparticles via one-pot aqueous process. Carbohydrate Polymers, 312: 120828. doi:10.1016/j.carbpol.2023.120828. [Abstract]
• Naraoka, H., Takano, Y., Dworkin, J.P., Oba, Y., Hamase, K., Furusho, A., Ogawa, N.O., Hashiguchi, M., Fukushima, K., Aoki, D., Schmitt-Kopplin, P., Aponte, J.C., Parker, E.T., Glavin, D.P., McLain, H.L., Elsila, J.E., Graham, H.V., Eiler, J.M., Orthous-Daunay, F.-R., Wolters, C., Isa, J., Vuitton, V., Thissen, R., Sakai, S., Yoshimura, T., Koga, T., Ohkouchi, N., Chikaraishi, Y., Sugahara, H., Mita, H., Furukawa, Y., Hertkorn, N., Ruf, A., Yurimoto, H., Nakamura, T., Noguchi, T., Okazaki, R., Yabuta, H., Sakamoto, K., Tachibana, S., Connolly, H.C., Lauretta, D.S., Abe, M., Yada, T., Nishimura, M., Yogata, K., Nakato, A., Yoshitake, M., Suzuki, A., Miyazaki, A., Furuya, S., Hatakeda, K., Soejima, H., Hitomi, Y., Kumagai, K., Usui, T., Hayashi, T., Yamamoto, D., Fukai, R., Kitazato, K., Sugita, S., Namiki, N., Arakawa, M., Ikeda, H., Ishiguro, M., Hirata, N., Wada, K., Ishihara, Y., Noguchi, R., Morota, T., Sakatani, N., Matsumoto, K., Senshu, H., Honda, R., Tatsumi, E., Yokota, Y., Honda, C., Michikami, T., Matsuoka, M., Miura, A., Noda, H., Yamada, T., Yoshihara, K., Kawahara, K., Ozaki, M., Iijima, Y.-i., Yano, H., Hayakawa, M., Iwata, T., Tsukizaki, R., Sawada, H., Hosoda, S., Ogawa, K., Okamoto, C., Hirata, N., Shirai, K., Shimaki, Y., Yamada, M., Okada, T., Yamamoto, Y., Takeuchi, H., Fujii, A., Takei, Y., Yoshikawa, K., Mimasu, Y., Ono, G., Ogawa, N., Kikuchi, S., Nakazawa, S., Terui, F., Tanaka, S., Saiki, T., Yoshikawa, M., Watanabe, S.-i., and Tsuda, Y. (2023) Soluble organic molecules in samples of the carbonaceous asteroid (162173) Ryugu. Science, 379(6634), eabn9033. doi:10.1126/science.abn9033. [Abstract]
• Nomaki, H., Kawatani, K., Motomura, Y., Tame, A., Uyeno, D., Ogawa, N.O., Ohkouchi, N., and Shimanaga, M. (2023) Bacterivory of the hydrothermal-vent-specific copepod Stygiopontius senokuchiae (Dirivultidae, Siphonostomatoida) from copepodite through adult stages. Journal of the Marine Biological Association of the United Kingdom, 103: e21. doi:10.1017/S0025315423000139. [Open Access]
• Oba, Y., Koga, T., Takano, Y., Ogawa, N.O., Ohkouchi, N., Sasaki, K., Sato, H., Glavin, D.P., Dworkin, J.P., Naraoka, H., Tachibana, S., Yurimoto, H., Nakamura, T., Noguchi, T., Okazaki, R., Yabuta, H., Sakamoto, K., Yada, T., Nishimura, M., Nakato, A., Miyazaki, A., Yogata, K., Abe, M., Okada, T., Usui, T., Yoshikawa, M., Saiki, T., Tanaka, S., Terui, F., Nakazawa, S., Watanabe, S.-i., Tsuda, Y., and Hayabusa2-initial-analysis, S.O.M.t. (2023) Uracil in the carbonaceous asteroid (162173) Ryugu. Nature Communications, 14: 1292. doi:10.1038/s41467-023-36904-3. [Open Access]
• Ohkouchi, N. (2023) A new era of isotope ecology: Nitrogen isotope ratio of amino acids as an approach for unraveling modern and ancient food web. Proceedings of the Japan Academy, Series B, 99(5), 131-154. doi:10.2183/pjab.99.009. [Open Access]
• Sun, Y., Ogawa, N.O., Ishikawa, N.F., Blattmann, T.M., Takano, Y., and Ohkouchi, N. (2023) Application of a porous graphitic carbon column to carbon and nitrogen isotope analysis of underivatized individual amino acids using high-performance liquid chromatography coupled with elemental analyzer/isotope ratio mass spectrometry. Rapid Communications in Mass Spectrometry, 37(17), e9602. doi:10.1002/rcm.9602. [Open Access]
• Tame, A., Maruyama, T., Ikuta, T., Chikaraishi, Y., Ogawa, N.O., Tsuchiya, M., Takishita, K., Tsuda, M., Hirai, M., Takaki, Y., Ohkouchi, N., Fujikura, K., and Yoshida, T. (2023) mTORC1 regulates phagosome digestion of symbiotic bacteria for intracellular nutritional symbiosis in a deep-sea mussel. Science Advances, 9(34), eadg8364. doi:10.1126/sciadv.adg8364. [Open Access]
• Yoshimura, T., Takano, Y., Naraoka, H., Koga, T., Araoka, D., Ogawa, N.O., Schmitt-Kopplin, P., Hertkorn, N., Oba, Y., Dworkin, J.P., Aponte, J.C., Yoshikawa, T., Tanaka, S., Ohkouchi, N., Hashiguchi, M., McLain, H., Parker, E.T., Sakai, S., Yamaguchi, M., Suzuki, T., Yokoyama, T., Yurimoto, H., Nakamura, T., Noguchi, T., Okazaki, R., Yabuta, H., Sakamoto, S., Yada, T., Nishimura, M., Nakato, A., Miyazaki, A., Yogata, K., Abe, M., Okada, T., Usui, T., Yoshikawa, M., Saiki, T., Tanaka, S., Terui, F., Nakazawa, S., Watanabe, S.-i., Tsuda, Y., Tachibana, S., and Hayabusa2-initial-analysis SOM team. (2023) Chemical evolution of primordial salts and organic sulfur molecules in the asteroid 162173 Ryugu. Nature Communications, 14: 5284. doi:10.1038/s41467-023-40871-0. [Open Access]
• Zeichner, S.S., Aponte, J.C., Bhattacharjee, S., Dong, G., Hofmann, A.E., Dworkin, J.P., Glavin, D.P., Elsila, J.E., Graham, H.V., Naraoka, H., Takano, Y., Tachibana, S., Karp, A.T., Grice, K., Holman, A.I., Freeman, K.H., Yurimoto, H., Nakamura, T., Noguchi, T., Okazaki, R., Yabuta, H., Sakamoto, K., Yada, T., Nishimura, M., Nakato, A., Miyazaki, A., Yogata, K., Abe, M., Okada, T., Usui, T., Yoshikawa, M., Saiki, T., Tanaka, S., Terui, F., Nakazawa, S., Watanabe, S.-i., Tsuda, Y., Hamase, K., Fukushima, K., Aoki, S., Hashiguchi, M., Mita, H., Chikaraishi, Y., Ohkouchi, N., Ogawa, N.O., Sakai, S., Parker, E.T., McLain, H.L., Orthous-Daunay, F.-R., Vuitton, V., Wolters, C., Schmitt-Kopplin, P., Hertkorn, N., Thissen, R., Ruf, A., Isa, J., Oba, Y., Koga, T., Yoshimura, T., Araoka, D., Sugahara, H., Furusho, A., Furukawa, Y., Aoki, J., Kano, K., Nomura, S.-i.M., Sasaki, K., Sato, H., Yoshikawa, T., Tanaka, S., Morita, M., Onose, M., Kabashima, F., Fujishima, K., Yamazaki, T., Kimura, Y., and Eiler, J.M. (2023) Polycyclic aromatic hydrocarbons in samples of Ryugu formed in the interstellar medium. Science, 382(6677), 1411-1416. doi:10.1126/science.adg6304. [Abstract]

2022

• Endo, I., Sakon, I., Onaka, T., Kimura, Y., Kimura, S., Wada, S., Helton, L.A., Lau, R.M., Kebukawa, Y., Muramatsu, Y., Ogawa, N.O., Ohkouchi, N., Nakamura, M., and Kwok, S. (2022) Towards the identification of carriers of the unidentified infrared (UIR) bands in novae. Proceedings of the International Astronomical Society, 16, 327-331. doi:10.1017/S1743921322000382. [Abstract]
• Etu-Sihvola, H., Salo, K., Naito, Y. I., Kytokari, M., Ohkouchi, N., Oinonen, M., Heyd, V., and Arppe, L. (2022) Isotopic insights into the early Medieval (600-1100 CE) diet in the Luistari cemetary at Eura, Finland. Archaeological and Anthropological Sciences, 14: 143. doi:10.1007/s12520-022-01613-3. [Open Access]
• Harada, Y., Ito, S., Ogawa, N.O., Yoshikawa, C., Ishikawa, N.F., Yoneda, M., and Ohkouchi, N. (2022) Compound-Specific Nitrogen Isotope Analysis of Amino Acids in Eye Lenses as a New Tool to Reconstruct the Geographic and Trophic Histories of Fish. Frontiers in Marine Science, 8:796532. doi:10.3389/fmars.2021.796532. [Open Access]
• Isaji, Y., Yoshikawa, C., Ogawa, N.O., Matsumoto, K., Makabe, A., Toyoda, S., Ishikawa, N.F., Ogawa, H., Saito, H., Honda, M.C., and Ohkouchi, N. (2022) Nitrogen sources for phytoplankton in the eastern Indian Ocean determined from δ15N of chlorophyll a and divinylchlorophyll a. Geochemistry, Geophysics, Geosystems, 23(4), e2021GC010057. doi:10.1029/2021GC010057. [Open Access]
• Ishikawa, N.F., Ogawa, N.O., Sun, Y., Chikaraishi, Y., Takano, Y., and Ohkouchi, N. (2022) Integrative assessment of amino acid nitrogen isotopic composition in biological tissue samples determined by GC/C/IRMS, LC × EA/IRMS, and LC × GC/C/IRMS. Limnology and Oceanography: Methods, 20(9), 531-542. doi:10.1002/lom3.10502. [Open Access]
• Kajita, H., Nakazawa, T., Utsunomiya, M., Ohkouchi, N., Sato, M., Harada, N., and Kawahata, H. (2022) Long-chain alkenones in the Shimosa Group reveal palaeotemperatures of the Pleistocene interglacial Palaeo-Tokyo Bays. Progress in Earth and Planetary Science, 9:40. doi:10.1186/s40645-022-00499-y. [Open Access]
• Kuroda, J., Hagino, K., Usui, Y., Bown, P.R., Hsiung, K.-H., Sakai, S., Hackney, R., Saito, S., Murayama, M., Ando, T., and Ohkouchi, N. (2022) Stratigraphy around the Cretaceous/Paleogene boundary in sediment cores from the Lord Howe Rise, Southwest Pacific. Geological Society of America Bulletin, 134(5-6), 1603-1613. doi:10.1130/B36112.1. [Abstract]
• Matsubayashi, J., Kimura, K., Ohkouchi, N., Ogawa, N. O., Ishikawa, N., Chikaraishi, Y., Tsuda, Y., and Minami, H. (2022) Using geostatistical analysis for simultaneous estimation of isoscapes and ontogenetic shifts in isotope ratios of highly migratory marine fish. Frontiers in Marine Science, 9: 1049056. doi:10.3389/fmars.2022.104905. [Open Access]
• Nitzsche, K.N., Yoshimura, T., Ishikawa, N.F., Kajita, H., Kawahata, H., Ogawa, N.O., Suzuki, K., Yokoyama, Y., and Ohkouchi, N. (2022) Metal contamination in a sediment core from Osaka Bay during the last 400 years. Progress in Earth and Planetary Science, 9:58. doi:10.1186/s40645-022-00517-z. [Open Access]
• Rey, L., Naito, Y., Ohkouchi, N., Chikaraishi, Y., Rottier, S., and Goude, G. (2022) Specifying subsistence strategies of Early farmers: new results from compound specific isotopic analysis of amino acids (CSIA-AA). International Journal of Osteoarchaeology, 32, 654-668. doi:10.1002/oa.3093. [Abstract]
• Tsutaya, T., Wong, A., Malim, P.T., Bernard, H., Ogawa, N.O., Ohkouchi, N., Hongo, S., Tajima, T., Kanamori, T., and Kuze, N. (2022) Stable isotopic investigation of the feeding ecology of wild Bornean orangutans. American Journal of Biological Anthropology, 179(2), 276-290. doi:10.1002/ajpa.24598. [Open Access]
• Toue, R., Fujita, K., Tsuchiya, M., Chikaraishi, Y., Sasaki, Y., and Ohkouchi, N. (2022) Trophic niche separation of two non-spinose planktonic foraminifers Neogloboquadrina dutertrei and Pulleniatina obliquiloculata. Progress in Earth and Planetary Science, 9: 20. doi:10.1186/s40645-022-00478-3. [Open Access]
• Urai, A., Takano, Y., Matsui, Y., Iwata, H., Miyairi, Y., Yokoyama, Y., Miyabara, Y., Ohkouchi, N., and Park, H.-D. (2022) Origin of Deep Methane from Active Faults along the Itoigawa-Shizuoka Tectonic Line between the Eurasian and North American Plates: ¹³C/¹²C and ¹⁴C/¹²C Methane Profiles from a Pull-Apart Basin at Lake Suwa. ACS Earth and Space Chemistry, 6(7), 1689-1697. doi:10.1021/acsearthspacechem.1c00392. [Open Access]
• Yoshikawa, C., Ogawa, N.O., Chikaraishi, Y., Makabe, A., Matsui, Y., Sasai, Y., Wakita, M., Honda, M.C., Mino, Y., Aita, M.N., Fujiki, T., Nunoura, T., Harada, N., and Ohkouchi, N. (2022) Nitrogen Isotopes of Sinking Particles Reveal the Seasonal Transition of the Nitrogen Source for Phytoplankton. Geophysical Research Letters, 49(17), e2022GL098670. doi:10.1029/2022GL098670. [Open Access]

2021

• Endo, I., Sakon, I., Onaka, T., Kimura, Y., Kimura, S., Wada, S., Helton, L.A., Lau, R.M., Kebukawa, Y., Muramatsu, Y., Ogawa, N.O., Ohkouchi, N., Nakamura, M., and Kwok, S. (2021) On the Nature of Organic Dust in Novae. Astrophysical Journal, 917(2):103. doi:10.3847/1538-4357/ac0cf1. [Open Access]
• Fujiwara, Y., Kawato, M., Poulsen, J.Y., Ida, H., Chikaraishi, Y., Ohkouchi, N., Oguri, K., Gotoh, S., Ozawa, G., Tanaka, S., Miya, M., Sado, T., Kimoto, K., Toyofuku, T., and Tsuchida, S. (2021) Discovery of a colossal slickhead (Alepocephaliformes: Alepocephalidae): an active-swimming top predator in the deep waters of Suruga Bay, Japan. Scientific Reports, 11, 2490. doi:10.1038/s41598-020-80203-6. [Open Access]
• Hallmann, C., Grosjean, E., Shapiro, N.D., Kashiyama, Y., Chikaraishi Y., Fike, D.A., Ohkouchi, N., and Summons R.E. (2021) Redox-controlled ammonium storage and overturn in Ediacaran oceans. Frontiers in Earth Science, 9, 706144. doi:10.3389/feart.2021.706144. [Open Access]
• Hsiung, K.-H., Kanamatsu, T., Ikehara, K., Usami, K., Horng, C.-S., Ohkouchi, N., Ogawa, N.O., Saito, S., and Murayama, M. (2021) X-ray fluorescence core scanning, magnetic signatures, and organic geochemistry analyses of Ryukyu Trench sediments: turbidites and hemipelagites. Progress in Earth and Planetary Science, 8:2. doi:10.1186/s40645-020-00396-2. [Open Access]
• Ishikawa, N.F., Ogawa, N.O., Chikaraishi, Y., Yamaguchi, M., Fujikura, K., Miyairi, Y., Yokoyama, Y., Nagata, T. and Ohkouchi, N. (2021) Influences of Ocean Currents on the Diets of Demersal Fish Communities in the Western North Pacific Revealed by Their Muscle Carbon and Nitrogen Isotopic Compositions. Frontiers in Marine Science, 8:641282. doi:10.3389/fmars.2021.641282. [Open Access]
• Kajita, H., Maeda, A., Utsunomiya, M., Yoshimura, T., Ohkouchi, N., Suzuki, A., and Kawahata, H. (2021) Biomarkers in the rock outcrop of the Kazusa Group reveal palaeoenvironments of the Kuroshio region. Communications Earth & Environment, 2:82. doi:10.1038/s43247-021-00154-2. [Open Access]
• Kaneko, M., Takano, Y., Kamo, M., Morimoto, K., Nunoura, T., and Ohkouchi, N. (2021) Insights into the Methanogenic Population and Potential in Subsurface Marine Sediments Based on Coenzyme F430 as a Function-Specific Biomarker. JACS Au, 1(10), 1743-1751. doi:10.1021/jacsau.1c00307. [Open Access]
• Kebukawa, Y., Zolensky, M.E., Goodrich, C.A., Ito, M., Ogawa, N.O., Takano, Y., Ohkouchi, N., Kiryu, K., Igisu, M., Shibuya, T., Ohigashi, T., Marcus, M.A., Kodama, Y., and Shaddad, M.H. (2021) Organic matter in carbonaceous chondrite lithologies of Almahata Sitta: Incorporation of previously unsampled carbonaceous chondrite lithologies into ureilitic regolith. Meteoritics and Planetary Science, 56(7), 1311-1327. doi.10.1111/maps.13713. [Abstract]
• Nitzsche, K.N., Yoshimura, T., Ishikawa, N.F., Ogawa, N.O., Suzuki, K. and Ohkouchi, N. (2021) Trace metal geochemical and Zn stable isotope data as tracers for anthropogenic metal contributions in a sediment core from Lake Biwa, Japan. Applied Geochemistry, 134:105107. doi:10.1016/j.apgeochem.2021.105107. [Abstract]
• Nomaki, H., Rastelli, E., Alves, A., Suga, H., Ramos, S., Kitahashi, T., Tsuchiya, M., Ogawa, N.O., Matsui, Y., Seike, K., Miyamoto, N., Corinaldesi, C., Manea, E., Ohkouchi, N., Danovaro, R., Nunoura, T., and Amaro, T. (2021) Abyssal fauna, benthic microbes, and organic matter quality across a range of trophic conditions in the western Pacific ocean. Progress in Oceanography, 195:102591. doi:10.1016/j.pocean.2021.102591. [Open Access]
• Nomaki, H., Rastelli, E., Ogawa, N.O., Matsui, Y., Tsuchiya, M., Manea, E., Corinaldesi, C., Hirai, M., Ohkouchi, N., Danovaro, R., Nunoura, T., Amaro, T. (2021) In situ experimental evidences for responses of abyssal benthic biota to shifts in phytodetritus compositions linked to global climate change. Global Change Biology, 27, 6139-6155. doi:10.1111/gcb.15882. [Open Access]
• Sproson, D.A., Takano, Y., Miyairi, Y., Aze, T., Matsuzaki, H., Ohkouchi, N., and Yokoyama, Y. (2021) Beryllium isotopes in sediments from Lake Maruwan Oike and Lake Skallen, East Antarctica, reveal substantial glacial discharge during the late Holocene. Quaternary Science Reviews, 256, 106841. doi:10.1016/j.quascirev.2021.106841. [Abstract]
• Takano, Y., Oba, Y., Furota, S., Naraoka, H., Ogawa, N.O., Blattmann, T.M., and Ohkouchi, N. (2021) Analytical development of seamless procedures on cation-exchange chromatography and ion-pair chromatography with high-precision mass spectrometry for short-chain peptides. International Journal of Mass Spectrometry, 463, 116529. doi:10.1016/j.ijms.2021.116529. [Open Access]
• Tsutaya, T., Ogawa, N.O., Nomura, T., Shimizu, M., Ohkouchi, N., and Kuze, N. (2021) Carbon and nitrogen stable isotopic offsets between diet and hair/feces in captive orangutans. Primates, 62, 945-954. doi:10.1007/s10329-021-00940-8. [Abstract]
• Urai, A., Matsushita, M., Park, H.-D., Imachi, H., Ogawara, M., Iwata, H., Kaneko, M., Ogawa, N.O., Ohkouchi, N., and Takano, Y. (2021) Detection of planktonic coenzyme factor 430 in a freshwater lake: small-scale analysis for probing archaeal methanogenesis. Progress in Earth and Planetary Science, 8:62. doi:10.1186/s40645-021-00450-7. [Open Access]
• Urai, A., Takano, Y., Imachi, H., Ishii, S., Matsui, Y., Ogawara, M., Tasumi, E., Miyairi, Y., Ogawa, N.O., Yoshimura, T., Inagaki, F., Yokoyama, Y., Murai, D., Kawano, K., Park, H.D., and Ohkouchi, N. (2021) Origin of Deep Methane Associated with a Unique Community of Microorganisms in an Organic- and Iodine-Rich Aquifer. ACS Earth and Space Chemsitry, 5(1), 1-11. doi:10.1021/acsearthspacechem.0c00204. [Abstract]
• Yamamoto, S., Nishizawa, F., Yoshimoto, M., Miyairi, Y., Yokoyama, Y., Suga, H., and Ohkouchi, N. (2021) Dating Lake Sediments Using Compound-Specific 14C Analysis of C16 Fatty Acid: A case study from the Mount Fuji Volcanic Region, Japan. Geochemistry Geophysics Geosystems, 22(5), e2020GC009544. doi:10.1029/2020GC009544. [Open Access]
• Yoshimura, T., Araoka, D., Kawahata, H., Hossain, H.M.Z., and Ohkouchi, N. (2021) The influence of weathering, water sources, and hydrological cycles on lithium isotopic compositions in river water and groundwater of the Ganges-Brahmaputra-Meghna River system in Bangladesh. Frontiers in Earth Science, 9:668757. doi:10.3389/feart.2021.668757. [Open Access]
• Yoshimura, T., Wakaki, S., Kawahata, H., Hossain, H.M.Z., Manaka, T., Suzuki, A., Ishikawa, T., and Ohkouchi, N. (2021) Stable Strontium Isotopic Compositions of River Water, Groundwater and Sediments From the Ganges-Brahmaputra-Meghna River System in Bangladesh. Frontiers in Earth Science, 9:592062. doi:10.3389/feart.2021.592062. [Open Access]

2020

• Bialik, O.M., Auer, G., Ogawa, N.O., Kroon, D., Waldmann, N.D., and Ohkouchi, N. (2020) Monsoons, Upwelling, and the Deoxygenation of the Northwestern Indian Ocean in Response to Middle to Late Miocene Global Climatic Shifts. Paleoceanography and Paleoclimatology, 35(2), e2019PA003762. doi:10.1029/2019PA003762. [Open Access]
• Isaji, Y., Ogawa, N.O., Boreham, C.J., Kashiyama, Y., and Ohkouchi, N. (2020) Evaluation of δ¹³C and δ¹⁵N uncertainties associated with the compound-specific isotope analysis of geoporphyrins. Analytical Chemistry, 92(4), 3152-3160. doi:10.1021/acs.analchem.9b04843. [Abstract]
• Isaji, Y., Ogawa, N.O., Takano, Y., and Ohkouchi, N. (2020) Quantification and carbon and nitrogen isotopic measurements of heme B in environmental samples. Analytical Chemistry, 92(16), 11213-11222. doi:10.1021/acs.analchem.0c01711. [Abstract]
• Ishikawa, N.F., Finlay, J.C., Uno, H., Ogawa, N.O., Ohkouchi, N., Tayasu, I., and Power, M.E. (2020) Combined use of radiocarbon and stable carbon isotopes for the source mixing model in a stream food web. Limnology and Oceanography, 65(11), 2688-2696. doi: 10.1002/lno.11541. [Abstract]
• Kajita, H., Nakamura, H., Ohkouchi, N., Harada, N., Sato, M., Tokioka, S., and Kawahata, H. (2020) Genomic and geochemical identification of the long-chain alkenone producers in the estuarine Lake Takahoko, Japan: Implications for temperature reconstructions. Organic Geochemistry, 142, 103980. doi:10.1016/j.orggeochem.2020.103980. [Abstract]
• Kebukawa, Y., Zolensky, M.E., Ito, M., Ogawa, N.O., Takano, Y., Ohkouchi, N., Nakato, A., Suga, H., Takeichi, Y., Takahashi, Y., and Kobayashi, K. (2019) Primordial organic matter in the xenolithic clast in the Zag H chondrite: Possible relation to D/P asteroids. Geochimica et Cosmochimica Acta, 271, 61-77. doi:10.1016/j.gca.2019.12.012. [Abstract]
• Matsubayashi, J., Osada, Y., Tadokoro, K., Abe, Y., Yamaguchi, A., Shirai, K., Honda, K., Yoshikawa, C., Ogawa, N.O., Ohkouchi, N., Ishikawa, N.F., Nagata, T., Miyamoto, H., Nishino, S., and Tayasu, I. (2020) Tracking long‐distance migration of marine fishes using compound‐specific stable isotope analysis of amino acids. Ecology Letters, 23(5), 881-890. doi:10.1111/ele.13496. [Abstract]
• Matsumoto, H., Kuroda, J., Coccioni, R., Frontalini, F., Sakai, S., Ogawa, N.O., and Ohkouchi, N. (2020) Marine Os isotopic evidence for multiple volcanic episodes during Cretaceous Oceanic Anoxic Event 1b. Scientific Reports, 10, 12601. doi:10.1038/s41598-020-69505-x. [Open Access]
• Prothro, L.O., Majewski, W., Yokoyama, Y., Simkins, L.M., Anderson, J.B., Yamane, M., Miyairi, Y., and Ohkouchi, N. (2020) Timing and pathways of East Antarctic Ice Sheet retreat. Quaternary Science Reviews, 230, 106166. doi:10.1016/j.quascirev.2020.106166. [Abstract]
• Sun, Y., Ishikawa, N.F., Ogawa, N.O., Kawahata, H., Takano, Y., and Ohkouchi, N. (2020) A method for stable carbon isotope measurement of underivatized individual amino acids by multi‐dimensional high‐performance liquid chromatography and elemental analyzer/isotope ratio mass spectrometry. Rapid Communications in Mass Spectrometry, 34(20), e8885. doi:10.1002/rcm.8885. [Abstract]
• Takizawa, Y., Takano, Y., Choi, B., Dharampal, P.S., Steffan, S.A., Ogawa, N.O., Ohkouchi, N., and Chikaraishi, Y. (2020) A new insight into isotopic fractionation associated with decarboxylation in organisms: implications for amino acid isotope approaches in biogeoscience. Progress in Earth and Planetary Science, 7:50. doi:10.1186/s40645-020-00364-w. [Open Access]
• Xing, D., Choi, B., Takizawa, Y., Fan, R., Sugaya, S., Tuchiya, M., Ohkouchi, N., and Chikaraishi, Y. (2020) Trophic hierarchy of coastal marine fish communities viewed via compound-specific isotopic analysis of amino acids. Marine Ecology Progress Series, 652, 137-144. doi:10.3354/meps13475. [Open Access]
• Yamamoto, S., Miyairi, Y., Yokoyama, Y., Suga, H., Ogawa, N.O., and Ohkouchi, N. (2020) Compound-Specific Radiocarbon Analysis of Organic Compounds from Mount Fuji Proximal Lake (Lake Kawaguchi) Sediment, Central Japan. Radiocarbon, 62(2), 439-451. doi:10.1017/RDC.2019.158. [Abstract]
• Yoshimura, T., Wakaki, S., Ishikawa, T., Gamo, T., Araoka, D., Ohkouchi, N., and Kawahata, H. (2020) A systematic assessment of stable Sr isotopic compositions of vent fluids in arc/back-arc hydrothermal systems: effects of host rock type, phase separation, and overlying sediment. Frontiers in Earth Science, 8:591711. doi:10.3389/feart.2020.591711. [Open Access]

2019

• Cortés-Sánchez, M., Jiménez-Espejo, F.J., Simón-Vallejo, M.D., Stringer, C., Lozano Francisco, M.C., García-Alix, A., Vera Peláez, J.L., Odriozola, C.P., Riquelme-Cantal, J.A., Parrilla Giráldez, R., Maestro González, A., Ohkouchi, N., and Morales-Muñiz, A. (2019) An early Aurignacian arrival in southwestern Europe. Nature Ecology & Evolution, 3, 207-212. doi:10.1038/s41559-018-0753-6. [Abstract]
• Cortés-Sánchez, M., Jiménez-Espejo, F.J., Simón-Vallejo, M.D., Stringer, C., Lozano Francisco, M.C., García-Alix, A., Vera Peláez, J.L., Odriozola, C.P., Riquelme-Cantal, J.A., Parrilla-Giráldez, R., Maestro González, A., Ohkouchi, N., and Morales-Muñiz, A. (2019) Reply to ‘Dating on its own cannot resolve hominin occupation patterns’ and ‘No reliable evidence for a very early Aurignacian in Southern Iberia’. Nature Ecology & Evolution, 3, 714-715. doi:10.1038/s41559-019-0887-1. [Abstract]
• Furukawa, Y., Chikaraishi, Y., Ohkouchi, N., Ogawa, N.O., Glavin, D.P., Dworkin, J.P., Abe, C., and Nakamura, T. (2019) Extraterrestrial ribose and other sugars in primitive meteorites. Proceedings of the National Academy of Sciences, 116(49), 24440-24445. doi:10.1073/pnas.1907169116. [Open Access]
• Goulden, S.K.E., Ohkouchi, N., Freeman, K.H., Chikaraishi, Y., Ogawa, N.O., Suga, H., Chadwick, O., and Houlton, B.Z. (2019) Strong correspondence between nitrogen isotope composition of foliage and chlorin across a rainfall gradient: implications for paleo-reconstruction of the nitrogen cycle. Biogeosciences, 16(19), 3869-3882. doi:10.5194/bg-16-3869-2019. [Open Access]
• Isaji, Y., Kawahata, H., Ogawa, N.O., Kuroda, J., Yoshimura, T., Jiménez-Espejo, F.J., Makabe, A., Shibuya, T., Lugli, S., Santulli, A., Manzi, V., Roveri, M., and Ohkouchi, N. (2019) Efficient recycling of nutrients in modern and past hypersaline environments. Scientific Reports, 9, 3718. doi:10.1038/s41598-019-40174-9. [Open Access]
• Isaji, Y., Kawahata, H., Takano, Y., Ogawa, N.O., Kuroda, J., Yoshimura, T., Lugli, S., Manzi, V., Roveri, M., and Ohkouchi, N. (2019) Diazotrophy drives primary production in the organic-rich shales deposited under a stratified environment during the Messinian salinity crisis (Vena del Gesso, Italy). Frontiers in Earth Science, 7, 85. doi:10.3389/feart.2019.00085. [Abstract]
• Isaji, Y., Yoshimura, T., Araoka, D., Kuroda, J., Ogawa, N.O., Kawahata, H., and Ohkouchi, N. (2019) Magnesium Isotope Fractionation during Synthesis of Chlorophyll a and Bacteriochlorophyll a of Benthic Phototrophs in Hypersaline Environments. ACS Earth and Space Chemistry, 3, 1073-1079. doi:10.1021/acsearthspacechem.9b00013. [Abstract]
• Isaji, Y., Yoshimura, T., Kuroda, J., Tamenori, Y., Jiménez-Espejo, F.J., Lugli, S., Manzi, V., Roveri, M., Kawahata, H., and Ohkouchi, N. (2019) Biomarker records and mineral compositions of the Messinian halite and K-Mg salts from Sicily. Progress in Earth and Planetary Science, 6:60. doi:10.1186/s40645-019-0306-x. [Open Access]
• Itahashi,Y., Erdal, Y.S., Tekin,H., Omar, L., Miyake, Y., Chikaraishi, Y., Ohkouchi, N., and Yoneda, M. (2019) Amino acid ¹⁵N analysis reveals change in the importance of freshwater resources between the hunter‐gatherer and farmer in the Neolithic upper Tigris. American Journal of Physical Anthropology, 168(4), 676-686. doi:10.1002/ajpa.23783. [Abstract]
• Maeda, A., Yoshimura, T., Araoka, D., Suzuki, A., Tamenori, Y., Fujita, K., Toyofuku, T., Ohkouchi, N., and Kawahata, H. (2019) Magnesium Isotopic Composition of Tests of Large Benthic Foraminifers: Implications for Biomineralization. Geochemistry, Geophysics, Geosystems. 20(8), 4046-4058. doi:10.1029/2019GC008314. [Abstract]
• Nomaki, H., Uejima, Y., Ogawa, N.O., Yamane, M., Watanabe, H.K., Senokuchi, R., Bernhard, J.M,, Kitahashi, T., Miyairi, Y., Yokoyama, Y., Ohkouchi, N., and Shimanaga, M. (2019) Nutritional source of meio- and macrofauna athydrothermal vents and adjacent fields: natural-abundance radiocarbon and stable isotope analyses. Marine Ecology Progress Series, 622, 49-65. doi:10.3354/meps13053. [Open Access]
• Sugahara, H., Takano, Y., Tachibana, S., Sugawara, I., Chikaraishi, Y., Ogawa, N.O., Ohkouchi, N., Kouchi, A., and Yurimoto, H. (2019) Molecular and isotopic compositions of nitrogen-containing organic molecules formed during UV-irradiation of simulated interstellar ice. Geochemical Journal, 53(1), 5-20. doi:10.2343/geochemj.2.0553. [Open Access]
• Wyatt, A.S.J., Matsumoto, R., Chikaraishi, Y., Miyairi, Y., Yokoyama, Y., Sato, K., Ohkouchi, N., and Nagata, T. (2019) Enhancing insights into foraging specialization in the world's largest fish using a multi‐tissue, multi‐isotope approach. Ecological Monographs, 89(1), e01339. doi:10.1002/ecm.1339. [Open Access]
• Yamane, M., Yokoyama, Y., Hirabayashi, S., Miyairi, Y., Ohkouchi, N., and Aze, T.(2019) Small- to ultra-small-scale radiocarbon measurements using newly installed AMS at the University of Tokyo. Nuclear Instruments in Physics Research B, 455, 238-243. doi:10.1016/j.nimb.2019.01.035. [Abstract]

2018

• Camuera, J., Jiménez-Moreno, G., Ramos-Román, M.J., García-Alix, A., Toney, J.L., Anderson, R.S., Jiménez-Espejo, F., Kaufman, D., Bright, J., Webster, C., Yanes, Y., Carrión, J.S., Ohkouchi, N., Suga, H., Yamame, M., Yokoyama, Y., and Martínez-Ruizj, F. (2018) Orbital-scale environmental and climatic changes recorded in a new ∼200,000-year-long multiproxy sedimentary record from Padul, southern Iberian Peninsula. Quaternary Science Reviews, 198, 91-114. doi:10.1016/j.quascirev.2018.08.014. [Open Access]
• Furota, S., Ogawa, N.O., Takano, Y., Yoshimura, T., and Ohkouchi, N. (2018) Quantitative analysis of underivatized amino acids in the sub- to several-nanomolar range by ion-pair HPLC using a corona-charged aerosol detector (HPLC-CAD). Journal of Chromatography B, 1095, 191-197. doi:10.1016/j.jchromb.2018.07.033. [Abstract]
• Goto, A.S., Miura, K., Korenaga, T., Hasegawa, T., Ohkouchi, N., and Chikaraishi, Y. (2018) Fractionation of stable nitrogen isotopes (¹⁵N/¹⁴N) during enzymatic deamination of glutamic acid: Implications for mass and energy transfers in the biosphere. Geochemical Journal, 52(3), 273-280. doi:10.2343/geochemj.2.0513. [Abstract]
• Gueneli, N., McKenna, A.M., Ohkouchi, N., Boreham, C.J., Beghin, J., Javaux, E.J., and Brocks, J.J. (2018) 1.1-billion-year-old porphyrins establish a marine ecosystem dominated by bacterial primary producers. Proceedings of the National Academy of Sciences of the United States of America, 115(30), 6978-6986. doi:10.1073/pnas.1803866115. [Abstract]
• Ishikawa, N.F., Chikaraishi, Y., Takano, Y., Sasaki, Y., Takizawa, Y., Tsuchiya, M., Tayasu, I., Nagata, T., and Ohkouchi, N. (2018) A new analytical method for determination of the nitrogen isotopic composition of methionine: Its application to aquatic ecosystems with mixed resources. Limnology and Oceanography: Methods, 16(9), 607-620. doi:10.1002/lom3.10272. [Open Access]
• Ishikawa, N.F., Itahashi, Y., Blattmann, T.M., Takano, Y., Ogawa, N.O., Yamane, M., Yokoyama, Y., Nagata, T., Yoneda, M., Haghipour, N., Eglinton, T.I., and Ohkouchi, N. (2018) Improved method for isolation and purification of underivatized amino acids for radiocarbon analysis. Analytical Chemistry, 90(20), 12035-12041. doi:10.1021/acs.analchem.8b02693. [Abstract]
• Itahashi, Y., Tsuneki, A., Dougherty, S.P., Chikaraishi, Y., Ohkouchi, N., and Yoneda, M. (2018) Dining together: Reconstruction of Neolithic food consumption based on the δ¹⁵N values for individual amino acids at Tell el-Kerkh, northern Levant. Journal of Archaeological Science: Reports, 17, 775-784. doi:10.1016/j.jasrep.2017.12.042. [Open Access]
• Jiménez-Espejo, F.J., García-Alix, A., Harada, N., Bahr, A., Sakai, S., Iijima, K., Chang, Q., Sato, K., Suzuki, K., and Ohkouchi, N. (2018) Changes in detrital input, ventilation and productivity in the central Okhotsk Sea during the marine isotope stage 5e, penultimate interglacial period. Journal of Asian Earth Sciences, 156, 189-200. doi:10.1016/j.jseaes.2018.01.032. [Abstract]
• Kajita, H, Kawahata, H., Wang, K., Zheng, H., Yang, S., Ohkouchi, N. Utsunomiya, M., Zhou, B., and Zheng, B. (2018) Extraordinary cold episodes during the mid-Holocene in the Yangtze delta: Interruption of the earliest rice cultivating civilization. Quaternary Science Reviews, 201, 418-428. doi:10.1016/j.quascirev.2018.10.035. [Open Access]
• Kobayashi, K., Tanaka, M., Yatsukawa, Y., Tanabe, S., Tanaka, M., and Ohkouchi, N. (2018) Development of a method to isolate glutamic acid from foodstuffs for a precise determination of their stable carbon isotope ratio. Analytical Science, 34(5), 571-574. doi:10.2116/analsci.17P450. [Open Access]
• Kondo, Y., Okada, S., Ohtsuka, S., Hirabayashi, T., Adachi, A., Urata, M., Toshino, S., Miyake, H., Ogawa, N.O., and Ohkouchi, N.(2018) Piscivory of the Japanese giant box jellyfish Morbakka virulenta. Plankton and Benthos Research, 13(2), 66-74. doi:10.3800/pbr.13.66. [Open Access]
• Nunoura, T., Chikaraishi, Y., Izaki, R., Suwa, T., Sato, T., Harada, T., Mori, K., Kato, Y., Miyazaki, M., Shimamura, S., Yanagawa, K., Shuto, A., Ohkouchi, N., Fujita, N., Takaki, Y., Atomi, H., and Takai, K. (2018) A primordial and reversible TCA cycle in a facultatively chemolithoautotrophic thermophile. Science, 359(6375), 559-563. doi:10.1126/science.aao3407. [Abstract]
• Sekine, Y., Kodama, K., Kobayashi, T., Obata, S., Chang, Y., Ogawa, N.O., Takano, Y., Ohkouchi, N., Saiki, K., and Sekine, T. (2018) An experimental study on impact-induced alterations of planetary organic simulants. Meteoritics and Planetary Science, 53(6), 1267-1282. doi:10.1111/maps.13075. [Abstract]
• Sugahara, H., Takano, Y., Karouji, Y., Kumagai, K., Yada, T., Ohkouchi, N., Abe, M., and Hayabusa2 project team. (2018) Amino acids on witness coupons collected from the ISAS/JAXA curation facility for the assessment and quality control of the Hayabusa2 sampling procedure. Earth, Planets and Space, 70(194). doi:10.1186/s40623-018-0965-7. [Open Access]
• Takano, Y., Chikaraishi, Y., Imachi, H., Miyairi, Y., Ogawa, N.O., Kaneko, M., Yokoyama, Y., Krüger, M., and Ohkouchi, N. (2018) Insight into anaerobic methanotrophy from ¹³C/¹²C- amino acids and ¹⁴C/¹²C-ANME cells in seafloor microbial ecology. Scientific Reports, 8:14070. doi:10.1038/s41598-018-31004-5. [Open Access]
• Tsuchiya, M., Chikaraishi, Y., Nomaki, H., Sasaki, Y., Tame, A., Uematsu, K., and Ohkouchi, N. (2018) Compound‐specific isotope analysis of benthic foraminifer amino acids suggests microhabitat variability in rocky‐shore environments. Ecology and Evolution, 8(16), 8380-8395. doi:10.1002/ece3.4358. [Open Access]
• Yoshikawa, C., Makabe, A., Matsui, Y., Nunoura, T., and Ohkouchi, N. (2018) Nitrate isotope distribution in the subarctic and subtropical North Pacific. Geochemistry, Geophysics, Geosystems, 19(7), 2212-2224. doi:10.1029/2018GC007528. [Open Access]
• Yoshimura, T., Araoka, D., Tamenori, Y., Kuroda, J., Kawahata, H., and Ohkouchi, N. (2018) Lithium, magnesium and sulfur purification from seawater using an ion chromatograph with a fraction collector system for stable isotope measurements. Journal of Chromatography A, 1531, 157-162. doi:10.1016/j.chroma.2017.11.052. [Open Access]

2017

• Campbell, C.J., Nelson, D.M., Ogawa, N.O., Chikaraishi, Y., and Ohkouchi, N. (2017) Trophic position and dietary breadth of bats revealed by nitrogen isotopic composition of amino acids. Scientific Reports, 7:15932. doi:10.1038/s41598-017-15440-3. [Open Access]
• Choi, B., Ha, S.-Y., Lee, J.S., Chikaraishi, Y., Ohkouchi, N., and Shin, K.-H. (2017) Trophic interaction among organisms in a seagrass meadow ecosystem as revealed by bulk δ¹³C and amino acid δ¹⁵N analyses. Limnology and Oceanography, 62(4), 1426-1435. doi:10.1002/lno.10508. [Abstract]
• Drucker, D.G., Naito, Y.I., Péan, S., Prat, S., Crépin, L., Chikaraishi, Y., Ohkouchi, N., Puaud, S., Lázničková-Galetová, M., Patou-Mathis, M., Yanevich, A., and Bocherens, H. (2017) Isotopic analyses suggest mammoth and plant in the diet of the oldest anatomically modern humans from far southeast Europe. Scientific Reports, 7:6833. doi:10.1038/s41598-017-07065-3. [Open Access]
• Isaji, Y., Kawahata, H., Kuroda, J., Yoshimura, T., Ogawa, N.O., Suzuki, A., Shibuya, T., Jiménez-Espejo, F.J., Lugli, S., Santulli, A., Manzi, V., Roveri, M., and Ohkouchi, N. (2017) Biological and physical modification of carbonate system parameters along the salinity gradient in shallow hypersaline solar salterns in Trapani, Italy. Geochimica et Cosmochimica Acta, 208, 354-367. doi:10.1016/j.gca.2017.04.013. [Abstract]
• Ishikawa, M., Ogawa, N.O., Ohkouchi, N., Husana, D.E.M., and Kase, T. (2017) Stable carbon isotope compositions of foot tissue, conchiolin opercula, and organic matrix within the shells of two marine gastropods from a seagrass meadow in the Philippines. Geochemical Journal, 51(3), 241-250. doi:10.2343/geochemj.2.0465. [Abstract]
• Ishikawa, N.F., Chikaraishi, Y., Ohkouchi, N., Murakami, A.R., Tayasu, I., Togashi, H., Okano, J., Sakai, Y., Iwata, T., Kondoh, M., and Okuda, N. (2017) Integrated trophic position decreases in more diverse communities of stream food webs. Scientific Reports, 7:2130. doi:10.1038/s41598-017-02155-8. [Open Access]
• Ishikawa, N.F., Hayashi, F., Sasaki, Y., Chikaraishi, Y., and Ohkouchi, N. (2017) Trophic discrimination factor of nitrogen isotopes within amino acids in the dobsonfly Protohermes grandis (Megaloptera: Corydalidae) larvae in a controlled feeding experiment. Ecology and Evolution, 7(6), 1674-1679. doi:10.1002/ece3.2728. [Open Access]
• Itahashi, Y., Miyake, Y., Maeda, O., Kondo, O., Hongo, H., Van Neer, W., Chikaraishi, Y., Ohkouchi, N., and Yoneda, M. (2017) Preference for fish in a Neolithic hunter-gatherer community of the upper Tigris, elucidated by amino acid δ¹⁵N analysis. Journal of Archaeological Science, 82, 40-49. doi:10.1016/j.jas.2017.05.001. [Abstract]
• Kinoshita, K., Takano, Y., Ohkouchi, N., and Deguchi, S. (2017) Free-radical polymerization of acrylic acid under extreme reaction conditions mimicking deep-sea hydrothermal vents. ACS Omega, 2(6), 2765-2769. doi:10.1021/acsomega.7b00293. [Open Access]
• Naeher, S., and Ohkouchi, N. (2017) Pigmente - Indikatoren für Umweltveränderungen. Nachrichten aus der Chemie, 65(1), 16-20. doi:10.1002/nadc.20174056149. [Abstract]
• Ohkouchi, N., Chikaraishi, Y., Close, H.G., Fry, B., Larsen, T., Madigan, D.J., McCarthy, M.D., McMahon, K.W., Nagata, T., Naito, Y.I., Ogawa, N.O., Popp, B.N., Steffan, S., Takano, Y., Tayasu, I., Wyatt, A.S.J., Yamaguchi, Y.T., and Yokoyama, Y. (2017) Advances in the application of amino acid nitrogen isotopic analysis in ecological and biogeochemical studies. Organic Geochemistry, 113, 150-174. doi:10.1016/j.orggeochem.2017.07.009. [Abstract]
  The Most Cited Organic Geochemistry Articles
• Sakai, S., Matsuda, S., Hikida, T., Shimono, A., McManus, J.B., Zahniser, M., Nelson, D., Dettman, D.L., Yang, D., and Ohkouchi, N. (2017) High-precision simultaneous ¹⁸O/¹⁶O, ¹³C/¹²C, and ¹⁷O/¹⁶O analyses for microgram quantities of CaCO₃ by tunable infrared laser absorption spectroscopy. Analytical Chemistry, 89(21), 11846-11852. doi:10.1021/acs.analchem.7b03582. [Abstract]
• Steffan, S.A., Chikaraishi, Y., Dharampal, P.S., Pauli, J.N., Guédot, C., and Ohkouchi, N. (2017) Unpacking brown food-webs: Animal trophic identity reflects rampant microbivory. Ecology and Evolution, 7(10), 3532-3541. doi:10.1002/ece3.2951. [Open Access]
• Sugahara, H., Takano, Y., Ogawa, N.O., Chikaraishi, Y., and Ohkouchi, N. (2017) Nitrogen isotopic fractionation in ammonia during adsorption on silicate surfaces. ACS Earth and Space Chemistry, 1(1), 24-29. doi:10.1021/acsearthspacechem.6b00006. [Open Access]
• Takishita, K., Chikaraishi, Y., Tanifuji, G., Ohkouchi, N., Hashimoto, T., Fujikura, K., and Roger, A.J. (2017) Microbial eukaryotes that lack sterols. Journal of Eukaryotic Microbiology, 64(6), 897-900. doi:10.1111/jeu.12426. [Abstract]
• Takishita, K., Takaki, Y., Chikaraishi, Y., Ikuta, T., Ozawa, G., Yoshida, T., Ohkouchi, N., and Fujikura, K. (2017) Genomic evidence that methanotrophic endosymbionts likely provide deep-sea Bathymodiolus mussels with a sterol intermediate in cholesterol biosynthesis. Genome Biology and Evolution, 9(5), 1148-1160. doi:10.1093/gbe/evx082. [Open Access]
• Takizawa, Y., Dharampal, P.S., Steffan, S.A., Takano, Y., Ohkouchi, N., and Chikaraishi, Y. (2017) Intra-trophic isotopic discrimination of ¹⁵N/¹⁴N for amino acids in autotrophs: Implications for nitrogen dynamics in ecological studies. Ecology and Evolution, 7(9), 2916-2924. doi:10.1002/ece3.2866. [Open Access]
• Williams, B., Thibodeau, B., Chikaraishi, Y., Ohkouchi, N., Walnum, A., Grottoli, A.G., and Colin, P.L. (2017) Consistency in coral skeletal amino acid composition offshore of Palau in the western Pacific warm pool indicates no impact of decadal variability in nitricline depth on primary productivity. Limnology and Oceanography, 62(2), 399-407. doi:10.1002/lno.10364. [Abstract]
• Yamaguchi, Y.T., Chikaraishi, Y., Takano, Y., Ogawa, N.O., Imachi, H., Yokoyama, Y., and Ohkouchi, N. (2017) Fractionation of nitrogen isotopes during amino acid metabolism in heterotrophic and chemolithoautotrophic microbes across Eukarya, Bacteria, and Archaea: Effects of nitrogen sources and metabolic pathways. Organic Geochemistry, 111, 101-112. doi:10.1016/j.orggeochem.2017.04.004. [Abstract]
• Yoshimura, T., Tamenori, Y., Suzuki, A., Kawahata, H., Iwasaki, N., Hasegawa, H., Nguyen, L.T., Kuroyanagi, A., Yamazaki, T., Kuroda, J., and Ohkouchi, N. (2017) Altervalent substitution of sodium for calcium in biogenic calcite and aragonite. Geochimica et Cosmochimica Acta, 202, 21-38. doi:10.1016/j.gca.2016.12.003. [Abstract]

2016

• Chan, Q.H.S., Chikaraishi, Y., Takano, Y., Ogawa, N.O., and Ohkouchi, N. (2016) Amino acid compositions in heated carbonaceous chondrites and their compound-specific nitrogen isotopic ratios. Earth, Planets and Space, 68(7). doi:10.1186/s40623-016-0382-8. [Open Access]
• Ishikawa, N.F., Togashi, H., Kato, Y., Yoshimura, M., Kohmatsu, Y., Yoshimizu, C., Ogawa, N.O., Ohte, N., Tokuchi, N., Ohkouchi, N., and Tayasu, I. (2016) Terrestrial-aquatic linkage in stream food webs along a forest chronosequence: multi-isotopic evidence. Ecology, 97(5), 1146-1158. doi:10.1890/15-1133.1. [Abstract]
• Kaneko, M., Takano, Y., Ogawa, N.O., Sato, Y., Yoshida, N., and Ohkouchi, N. (2016) Estimation of methanogenesis by quantification of coenzyme F430 in marine sediments. Geochemical Journal, 50(6), 453-460. doi:10.2343/geochemj.2.0410. [Open Access]
• Kondo, Y., Ohtsuka, S., Hirabayashi, T., Okada, S., Ogawa, N.O., Ohkouchi, N., Shimazu, T., and Nishikawa, J. (2016) Seasonal changes in infection with trematode species utilizing jellyfish as hosts: evidence of transmission to definitive host fish via medusivory. Parasite, 23(16). doi:10.1051/parasite/2016016. [Open Access]
• Kruger, B.R., Werne, J.P., Branstrator, D.K., Hrabik, T.R., Chikaraishi, Y., Ohkouchi, N., and Minor, E.C. (2016) Organic matter transfer in Lake Superior's food web: Insights from bulk and molecular stable isotope and radiocarbon analyses. Limnology and Oceanography, 61(1), 149-164. doi:10.1002/lno.10205. [Abstract]
• Kuroda, J., Jiménez-Espejo, F.J., Nozaki, T., Gennari, R., Lugli, S., Manzi, V., Roveri, M., Flecker, R., Sierro, F.J., Yoshimura, T., Suzuki, K., and Ohkouchi, N. (2016) Miocene to Pleistocene osmium isotopic records of the Mediterranean sediments. Paleoceanography, 31(1), 148-166. doi:10.1002/2015PA002853. [Open Access]
• Naeher, S., Suga, H., Ogawa, N.O., Schubert, C.J., Grice, K., and Ohkouchi, N. (2016) Compound-specific carbon and nitrogen isotopic compositions of chlorophyll a and its derivatives reveal the eutrophication history of Lake Zurich (Switzerland). Chemical Geology, 443, 210-219. doi:10.1016/j.chemgeo.2016.09.005. [Abstract]
• Naeher, S., Suga, H., Ogawa, N.O., Takano, Y., Schubert, C.J., Grice, K., and Ohkouchi, N. (2016) Distributions and compound-specific isotopic signatures of sedimentary chlorins reflect the composition of photoautotrophic communities and their carbon and nitrogen sources in Swiss lakes and the Black Sea. Chemical Geology, 443, 198-209. doi:10.1016/j.chemgeo.2016.04.029. [Abstract]
• Naito, Y.I., Bocherens, H., Chikaraishi, Y., Drucker, D.G., Wißing, C., Yoneda, M., and Ohkouchi, N. (2016) An overview of methods used for the detection of aquatic resource consumption by humans: Compound-specific delta N-15 analysis of amino acids in archaeological materials. Journal of Archaeological Science: Reports, 6, 720-732. doi:10.1016/j.jasrep.2015.11.025. [Abstract]
• Naito, Y.I., Chikaraishi, Y., Drucker, D.G., Ohkouchi, N., Semal, P., Wißing, C., and Bocherens, H. (2016) Ecological niche of Neanderthals from Spy Cave revealed by nitrogen isotopes of individual amino acids in collagen. Journal of Human Evolution, 93, 82-90. doi:10.1016/j.jhevol.2016.01.009. [Abstract]
• Naito, Y.I., Germonpré, M., Chikaraishi, Y., Ohkouchi, N., Drucker, D.G., Hobson, K.A., Edwards, M.A., Wißing, C., and Bocherens, H. (2016) Evidence for herbivorous cave bears (Ursus spelaeus) in Goyet Cave, Belgium: Implications for paleodietary reconstruction of fossil bears using amino acid δ¹⁵N approaches. Journal of Quaternary Science, 31(6), 598-606. doi:10.1002/jqs.2883. [Abstract]
• Ohkouchi, N., Shibata, H., Chikaraishi, Y., Nomaki, H., Ogawa, N.O., Nagata, T., Goto, T., Fujikura, K., and Kitazato, H. (2016) A monitoring result of polychlorinated biphenyls (PCBs) in deep-sea organisms and sediments off Tohoku during 2012-2014: temporal variation and the relationship with the trophic position. Journal of Oceanography, 72(4), 629-639. doi:10.1007/s10872-016-0359-z. [Abstract]
• van Soelen, E.E., Ohkouchi, N., Suga, H., Sinninghe Damsté, J.S., and Reichart, G.-J. (2016) A late Holocene molecular hydrogen isotope record of the East Asian Summer Monsoon in Southwest Japan. Quaternary Research, 86(3), 287-294. doi:10.1016/j.yqres.2016.07.005. [Abstract]
• Yokoyama, Y., Anderson, J.B., Yamane, M., Simkins, L.M., Miyairi, Y., Yamazaki, T., Koizumi, M., Suga, H., Kusahara, K., Prothro, L., Hasumi, H., Southon, J.R., and Ohkouchi, N. (2016) Widespread collapse of the Ross Ice Shelf during the late Holocene. Proceedings of the National Academy of Sciences of the United States of America, 113(9), 2354-2359. doi:10.1073/pnas.1516908113. [Open Access]
• Yoshikawa, C., Abe, H., Aita, M.N., Breider, F., Kuzunuki, K., Toyoda, S., Ogawa, N.O., Suga, H., Ohkouchi, N., Danielache, S.O., Wakita, M., Honda, M.C., and Yoshida, N. (2016) Insight into nitrous oxide production processes in the western North Pacific based on a marine ecosystem isotopomer model. Journal of Oceanography, 72(3), 491-508. doi:10.1007/s10872-015-0308-2. [Abstract]
• Yoshimura, T., Kuroda, J., Lugli, S., Tamenori, Y., Ogawa, N.O., Jiménez-Espejo, F.J., Isaji, Y., Roveri, M., Manzi, V., Kawahata, H., and Ohkouchi, N. (2016) An X-ray spectroscopic perspective on Messinian evaporite from Sicily: Sedimentary fabrics, element distributions, and chemical environments of S and Mg. Geochemistry, Geophysics, Geosystems, 17(4), 1383-1400. doi:10.1002/2015GC006233. [Open Access]

2015

• Chikaraishi, Y., Steffan, S.A., Takano, Y., and Ohkouchi, N. (2015) Diet quality influences isotopic discrimination among amino acids in an aquatic vertebrate. Ecology and Evolution, 5(10), 2048-2059. doi:10.1002/ece3.1491. [Open Access]
• Inagaki, F., Hinrichs, K.-U., Kubo, Y., Bowles, M.W., Heuer, V.B., Hong, W.-L., Hoshino, T., Ijiri, A., Imachi, H., Ito, M., Kaneko, M., Lever, M.A., Lin, Y.-S., Methé, B.A., Morita, S., Morono, Y., Tanikawa, W., Bihan, M., Bowden, S.A., Elvert, M., Glombitza, C., Gross, D., Harrington, G.J., Hori, T., Li, K., Limmer, D., Liu, C.-H., Murayama, M., Ohkouchi, N., Ono, S., Park, Y.-S., Phillips, S.C., Prieto-Mollar, X., Purkey, M., Riedinger, N., Sanada, Y., Sauvage, J., Snyder, G., Susilawati, R., Takano, Y., Tasumi, E., Terada, T., Tomaru, H., Trembath-Reichert, E., Wang, D.T., and Yamada, Y. (2015) Exploring deep microbial life in coal-bearing sediment down to ~2.5 km below the ocean floor. Science, 349(6246), 420-424. doi:10.1126/science.aaa6882. [Abstract]
• Isaji, Y., Kawahata, H., Ohkouchi, N., Murayama, M., and Tamaki, K. (2015) Terrestrial environmental changes around the Gulf of Aden over the last 210 kyr deduced from the sediment n-alkane record: Implications for the dispersal of Homo sapiens. Geophysical Research Letters, 42(6), 1880-1887. doi:10.1002/2015GL063196. [Open Access]
• Isaji, Y., Kawahata, H., Ohkouchi, N., Ogawa, N.O., Murayama, M., Inoue, K., and Tamaki, K. (2015) Varying responses to Indian monsoons during the past 220 kyr recorded in deep-sea sediments in inner and outer regions of the Gulf of Aden. Journal of Geophysical Research: Oceans, 120(11), 7253-7270. doi:10.1002/2015JC010982. [Open Access]
• Ishikawa, N.F., Tayasu, I., Yamane, M., Yokoyama, Y., Sakai, S., and Ohkouchi, N. (2015) Sources of dissolved inorganic carbon in two small streams with different bedrock geology: insights from carbon isotopes. Radiocarbon, 57(3), 439-448. doi:10.2458/azu_rc.57.18348. [Open Access]
• Ishikawa, N.F., Yamane, M., Suga, H., Ogawa, N.O., Yokoyama, Y., and Ohkouchi, N. (2015) Chlorophyll a-specific Δ¹⁴C, δ¹³C and δ¹⁵N values in stream periphyton: implications for aquatic food web studies. Biogeosciences, 12(22), 6781-6789. doi:10.5194/bg-12-6781-2015. [Open Access]
• Kuroda, J., Ihoriya, N., Hori, R.S., Ogawa, N.O., Ikehara, M., Tanimizu, M., and Ohkouchi, N. (2015) Geochemistry of an Aptian bedded chert succession from the deep Pacific basin: New insights into Cretaceous oceanic anoxic event (OAE) 1a. Geological Society of America Special Papers, 511, 305-328. doi:10.1130/2015.2511(16). [Abstract]
• Kusuno, H., Matsuzaki, H., Nagata,T., Miyairi, Y., Yokoyama, Y., and Ohkouchi, N. (2015) An approach for measuring the ¹²⁹I/¹²⁷I ratio in fish samples. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 361, 414-418. doi:10.1016/j.nimb.2015.04.074. [Abstract]
• Miyachi, S., Mayahara, T., Tsushima, K., Sasada, K., Kohno, E., Ogawa, N.O., Chikaraishi, Y., and Ohkouchi, N. (2015) Approach to determine individual trophic level and the difference in food sources of Japanese anchovy Engraulis japonicus in Sagami Bay, based on compound-specific nitrogen stable isotope analysis of amino acids. Fisheries Science, 81(6), 1053-1062. doi:10.1007/s12562-015-0923-2. [Abstract]
• Monge, G., Jiménez-Espejo, F.J., García- Alix, A., Martínez-Ruiz, F., Mattielli, N., Finlayson, C., Ohkouchi, N., Sánchez, M.C., Bermúdez de Castro, J.M., Blasco, R., Rosell, J., Carrión, J., Rodríguez-Vidal, J., and Finlayson, G. (2015) Earliest evidence of pollution by heavy metals in archaeological sites. Scientific Reports, 5:14252. doi:10.1038/srep14252. [Open Access]
• Nomaki, H., Chikaraishi, Y., Tsuchiya, M., Toyofuku, T., Suga, H., Sasaki, Y., Uematsu, K., Tame, A., and Ohkouchi, N. (2015) Variation in the nitrogen isotopic composition of amino acids in benthic foraminifera: Implications for their adaptation to oxygen-depleted environments. Limnology and Oceanography, 60(6), 1906-1916. doi:10.1002/lno.10140. [Abstract]
• Ohkouchi, N., Kuroda, J., and Taira, A. (2015) The origin of Cretaceous black shales: a change in the surface ocean ecosystem and its triggers. Proceedings of the Japan Academy, Series B, 91(7), 273-291. doi:10.2183/pjab.91.273. [Open Access]
• Ohkouchi, N., Ogawa, N.O., Chikaraishi, Y., Tanaka, H., and Wada, E. (2015) Biochemical and physiological bases for the use of carbon and nitrogen isotopes in environmental and ecological studies. Progress in Earth and Planetary Science, 2(1), doi:10.1186/s40645-015-0032-y. [Open Access] 
  PEPS The Most Accessed Paper Award 2017
  PEPS The Most Cited Paper Award 2018
• Sakon, I., Sato, K., Onaka, T., Kimura, S., Wada, S., Ogawa, N.O., Ohkouchi, N., and Pathak, A. (2015) Infrared Properties of laboratory-synthesized Nitrogen-containing Carbonaceous Composites (NCCs). Asian Journal of Physics, 24(8), 1143-1150. [Abstract]
• Steffan, S.A., Chikaraishi, Y., Currie, C.R., Horn, H., Gaines-Day, H.R., Pauli, J.N., Zalapa, J.E., and Ohkouchi, N. (2015) Microbes are trophic analogs of animals. Proceedings of the National Academy of Sciences of the United States of America, 112(49), 15119-15124. doi:10.1073/pnas.1508782112. [Open Access]
• Steffan, S.A., Chikaraishi, Y., Horton, D.R., Miliczky, E., Zalapa, J.E., Jones, V.P., and Ohkouchi, N. (2015) Beneficial or not? Decoding carnivore roles in plant protection. Biological Control, 91, 34-41. doi:10.1016/j.biocontrol.2015.07.002. [Abstract]
• Takano, Y., Chikaraishi, Y., and Ohkouchi, N. (2015) Isolation of underivatized amino acids by ion-pair high performance liquid chromatography for precise measurement of nitrogen isotopic composition of amino acids: Development of comprehensive LC x GC/C/IRMS method. International Journal of Mass Spectrometry, 379, 16-25. doi:10.1016/j.ijms.2014.11.012. [Open Access]

2014

• Chikaraishi, Y., Steffan, S.A., Ogawa, N.O., Ishikawa, N.F., Sasaki, Y., Tsuchiya, M., and Ohkouchi, N. (2014) High-resolution food webs based on nitrogen isotopic composition of amino acids. Ecology and Evolution, 4(12), 2423-2449. doi:10.1002/ece3.1103. [Open Access]
• Itahashi, Y., Chikaraishi, Y., Ohkouchi, N., and Yoneda, M. (2014) Refinement of reconstructed ancient food webs based on the nitrogen isotopic compositions of amino acids from bone collagen: A case study of archaeological herbivores from Tell Ain el-Kerkh, Syria. Geochemical Journal, 48(4), e15-e19. doi:10.2343/geochemj.2.0318. [Open Access]
• Kaneko, M., Takano, Y., Chikaraishi, Y., Ogawa, N.O., Asakawa, S., Watanabe, T., Shima, S., Krüger, M., Matsushita, M., Kimura, H., and Ohkouchi, N. (2014) Quantitative analysis of coenzyme F430 in environmental samples: a new diagnostic tool for methanogenesis and anaerobic methane oxidation. Analytical Chemistry, 86(7), 3633-3638. doi:10.1021/ac500305j. [Open Access]
• Maki, K., Ohkouchi, N., Chikaraishi, Y., Fukuda, H., Miyajima, T., and Nagata, T. (2014) Influences of nitrogen substrates and substrate C:N ratios on the nitrogen isotopic composition of amino acids from the marine bacterium Vibrio harveyi. Geochimica et Cosmochimica Acta, 140, 521-530. doi:10.1016/j.gca.2014.05.052. [Open Access]
• Nakayama, T., Kamikawa, R., Tanifuji, G., Kashiyama, Y., Ohkouchi, N., Archibald, J.M., and Inagaki, Y. (2014) Complete genome of a nonphotosynthetic cyanobacterium in a diatom reveals recent adaptations to an intracellular lifestyle. Proceedings of the National Academy of Sciences of the United States of America, 111(31), 11407-11412. doi:10.1073/pnas.1405222111. [Open Access]
• Nomaki, H., Chikaraishi, Y., Tsuchiya, M., Toyofuku, T., Ohkouchi, N., Uematsu, K., Tame, A., and Kitazato, H. (2014) Nitrate uptake by foraminifera and use in conjunction with endobionts under anoxic conditions. Limnology and Oceanography, 59(6), 1879-1888. doi:10.4319/lo.2014.59.6.1879. [Open Access]
• Ohkouchi, N., and Takano, Y. (2014) Organic nitrogen: sources, fates, and chemistry. Treatise on Geochemistry, Vol. 12, 10: Organic Geochemistry (Edited by Birrer, B., Falkowski, P., Freeman, K.), Elsevier, pp. 251-289. doi:10.1016/B978-0-08-095975-7.01015-9. [Open Access]
• Yamane, M., Yokoyama, Y., Miyairi, Y., Suga, H., Matsuzaki, H., Dunbar, R.B., and Ohkouchi, N. (2014) Compound-Specific ¹⁴C dating of IODP Expedition 318 core U1357A obtained off the Wilkes Land coast, Antarctica. Radiocarbon, 56(3), 1009-1017. doi:10.2458/56.17773. [Open Access]

2013

• Goto, K.T., Sekine, Y., Suzuki, K., Tajika, E., Senda, R., Nozaki, T., Tada, R., Goto, K., Yamamoto, S., Maruoka, T., Ohkouchi, N., and Ogawa, N.O. (2013) Redox conditions in the atmosphere and shallow-marine environments during the first Huronian deglaciation: Insights from Os isotopes and redox-sensitive elements. Earth and Planetary Science Letters, 376, 145-154. doi:10.1016/j.epsl.2013.06.018. [Abstract]
• Kaneko, M., Naraoka, H., Takano, Y., and Ohkouchi, N. (2013) Distribution and isotopic signatures of archaeal lipid biomarkers associated with gas hydrate occurrences on the northern Cascadia Margin. Chemical Geology, 343, 76-84. doi:10.1016/j.chemgeo.2013.02.003. [Abstract]
• Kurosawa, K., Sugita, S., Ishibashi, K., Hasegawa, S., Sekine, Y., Ogawa, N.O., Kadono, T., Ohno, S., Ohkouchi, N., Nagaoka, Y., and Matsui, T. (2013) Hydrogen cyanide production due to mid-size impacts in a redox-neutral N₂-rich atmosphere. Origins of Life and Evolution of Biospheres, 43(3), 221-245. doi:10.1007/s11084-013-9339-0. [Abstract]
• Naito, Y.I., Chikaraishi, Y., Ohkouchi, N., Drucker, D.G., and Bocherens, H. (2013) Nitrogen isotopic composition of collagen amino acids as an indicator of aquatic resource consumption: insights from Mesolithic and Epipalaeolithic archaeological sites in France. World Archaeology, 45(3), 338-359. doi:10.1080/00438243.2013.820650. [Abstract]
• Naito, Y.I., Chikaraishi, Y., Ohkouchi, N., and Yoneda, M. (2013) Evaluation of carnivory in inland Jomon hunter-gatherers based on nitrogen isotopic compositions of individual amino acids in bone collagen. Journal of Archaeological Science, 40(7), 2913-2923. doi:10.1016/j.jas.2013.03.012. [Abstract]
• Ogawa, N.O., Chikaraishi, Y., and Ohkouchi, N. (2013) Trophic position estimates of formalin-fixed samples with nitrogen isotopic compositions of amino acids: an application to gobiid fish (Isaza) in Lake Biwa, Japan. Ecological Research, 28(5), 697-702. doi:10.1007/s11284-012-0967-z. [Abstract]
• Ohkouchi, N., Tsuda, R., Chikaraishi, Y., and Tanabe, K. (2013) A preliminary estimate of the trophic position of the deep-water ram’s horn squid Spirula spirula based on the nitrogen isotopic composition of amino acids. Marine Biology, 160(4), 773-779. doi:10.1007/s00227-012-2132-1. [Abstract]
• Schouten, S., Hopmans, E.C., Rosell-Melé, A., Pearson, A., Adam, P., Bauersachs, T., Bard, E., Bernasconi, S.M., Bianchi, T.S., Brocks, J.J., Carlson, L.T., Castañeda, I.S., Derenne, S., Selver, A.D., Dutta, K., Eglinton, T., Fosse, C., Galy, V., Grice, K., Hinrichs, K.-U., Huang, Y., Huguet, A., Huguet, C., Hurley, S., Ingalls, A., Jia, G., Keely, B., Knappy, C., Kondo, M., Krishnan, S., Lincoln, S., Lipp, J., Mangelsdorf, K., Martínez-García, A., Ménot, G., Mets, A., Mollenhauer, G., Ohkouchi, N., Ossebaar, J., Pagani, M., Pancost, R.D., Pearson, E.J., Peterse, F., Reichart, G.-J., Schaeffer, P., Schmitt, G., Schwark, L., Shah, S.R., Smith, R.W., Smittenberg, R.H., Summons, R.E., Takano, Y., Talbot, H.M., Taylor, K.W.R., Tarozo, R., Uchida, M., van Dongen, B.E., Van Mooy, B.A.S., Wang, J., Warren, C., Weijers, J.W.H., Werne, J.P., Woltering, M., Xie, S., Yamamoto, M., Yang, H., Zhang, C.L., Zhang, Y., Zhao, M., and Sinninghe Damsté, J.S. (2013) An interlaboratory study of TEX₈₆ and BIT analysis of sediments, extracts and standard mixtures. Geochemistry, Geophysics, Geosystems, 14(12), 5263-5285. doi:10.1002/2013GC004904. [Open Access]
• Steffan, S.A., Chikaraishi, Y., Horton, D.R., Ohkouchi, N., Singleton, M.E., Miliczky, E., Hogg, D.B., and Jones, V.P. (2013) Trophic hierarchies illuminated via amino acid isotopic analysis. PLoS ONE, 8(9): e76152. doi:10.1371/journal.pone.0076152. [Open Access]
• Takano, Y., Kaneko, M., Kahnt, J., Imachi, H., Shima, S., and Ohkouchi, N. (2013) Detection of coenzyme F430 in deep sea sediments: A key molecule for biological methanogenesis. Organic Geochemistry, 58, 137-140. doi:10.1016/j.orggeochem.2013.01.012. [Open Access]

2012

• Chikaraishi Y., Kaneko, M., and Ohkouchi N. (2012) Stable hydrogen and carbon isotopic compositions of long-chain (C₂₁-C₃₃) n-alkanes and n-alkenes in insects. Geochimica et Cosmochimica Acta, 95, 53-62. doi:10.1016/j.gca.2012.07.036. [Open Access]
• Miller, M.J., Chikaraishi, Y., Ogawa, N.O., Yamada, Y., Tsukamoto, K., and Ohkouchi, N. (2012) A low trophic position of Japanese eel larvae indicates feeding on marine snow. Biology Letters, 9(1). doi:10.1098/rsbl.2012.0826. [Open Access]
• Sakuma, H., Tada, R., Ikeda, M., Kashiyama, Y., Ohkouchi, N., Ogawa, N.O., Watanabe, S., Tajika, E., and Yamamoto, S. (2012) High-resolution lithostratigraphy and organic carbon isotope stratigraphy of the Lower Triassic pelagic sequence in central Japan. Island Arc, 21(2), 79-100. doi:10.1111/j.1440-1738.2012.00809.x. [Open Access]
• Takano, Y., Tyler, J.J., Kojima, H., Yokoyama, Y., Tanabe, Y., Sato, T., Ogawa, N.O., Ohkouchi, N., and Fukui, M. (2012) Holocene lake development and glacial-isostatic uplift at Lake Skallen and Lake Oyako, Lützow-Holm Bay, East Antarctica: Based on biogeochemical facies and molecular signatures. Applied Geochemistry, 27(12), 2546-2559. doi:10.1016/j.apgeochem.2012.08.009. [Open Access]
• Takishita, K., Chikaraishi, Y., Leger, M.M., Kim, E., Yabuki, A., Ohkouchi, N., and Roger, A.J. (2012) Lateral transfer of tetrahymanol-synthesizing genes has allowed multiple diverse eukaryote lineages to independently adapt to environments without oxygen. Biology Direct, 7(5). doi:10.1186/1745-6150-7-5. [Open Access]

2011

• Chikaraishi, Y., Ogawa, N.O., Doi, H., and Ohkouchi, N. (2011) ¹⁵N/¹⁴N ratios of amino acids as a tool for studying terrestrial food webs: a case study of terrestrial insects (bees, wasps, and hornets). Ecological Research, 26(4), 835-844. doi:10.1007/s11284-011-0844-1. [Open Access] Ecological Research Award, 2011
• Enge, A.J., Nomaki, H., Ogawa, N.O., Witte, U., Moeseneder, M.M., Lavik, G., Ohkouchi, N., Kitazato, H., Kučera, M., and Heinz, P. (2011) Response of the benthic foraminiferal community to a simulated short-term phytodetritus pulse in the abyssal North Pacific. Marine Ecology Progress Series, 438, 129-142. doi:10.3354/meps09298. [Abstract]
• Kohzu, A., Imai, A., Ohkouchi, N., Fukushima, T., Kamiya, K., Komatsu, K., Tomioka, N., Kawasaki, N., Miura, S., and Satou, T. (2011) Direct evidence for the alteration of ¹³C natural abundances during early diagenesis in Lake Kasumigaura, Japan. Geochemistry, Geophysics, Geosystems, 12(10). doi:10.1029/2011GC003532. [Open Access]
• Kuroda, J., Tanimizu, M., Hori, R.S., Suzuki, K., Ogawa, N.O., Tejada, M.L.G., Coffin, M.F., Coccioni, R., Erba, E., and Ohkouchi, N. (2011) Lead isotopic record of Barremian-Aptian marine sediments: Implications for large igneous provinces and the Aptian climatic crisis. Earth and Planetary Science Letters, 307, 126-134. doi:10.1016/j.epsl.2011.04.021. [Open Access]
• Nomaki, H., Ogawa, N.O., Takano, Y., Suga, H., Ohkouchi, N., and Kitazato, H. (2011) Differing utilization of glucose and algal particulate organic matter by deep-sea benthic organisms of Sagami Bay, Japan. Marine Ecology Progress Series, 431, 11-24. doi:10.3354/meps09144. [Open Access]
• Sekine, Y., Suzuki, K., Senda, R., Goto, K.T., Tajika, E., Tada, R., Goto, K., Yamamoto, S., Ohkouchi, N., Ogawa, N.O., and Maruoka, T. (2011) Osmium evidence for synchronicity between a rise in atmospheric oxygen and Palaeoproterozoic deglaciation. Nature Communications, 2(502). doi:10.1038/ncomms1507. [Open Access]
• Strable M.S., Tschanz, C.L., Varamini, B., Chikaraishi, Y., Ohkouchi, N., and Brenna, J.T. (2011) Mammalian DNA δ¹⁵N exhibits 40‰ intramolecular variation and is unresponsive to dietary protein level. Rapid Communications in Mass Spectrometry, 25(23), 3555-3562. doi:10.1002/rcm.5263. [Abstract]
• Tayasu, I., Hirasawa, R., Ogawa, N.O., Ohkouchi, N., and Yamada, K. (2011) New organic reference materials for carbon- and nitrogen-stable isotope ratio measurements provided by Center for Ecological Research, Kyoto University, and Institute of Biogeosciences, Japan Agency for Marine-Earth Science and Technology. Limnology, 12(3), 261-266. doi:10.1007/s10201-011-0345-5. [Abstract]
• Toyoda, S., Yano, M., Nishimura, S., Akiyama, H., Hayakawa, A., Koba, K., Sudo, S., Yagi, K., Makabe, A., Tobari, Y., Ogawa, N.O., Ohkouchi, N., Yamada, K., and Yoshida, N. (2011) Characterization and production and consumption processes of N₂O emitted from temperate agricultural soils determined via isotopomer ratio analysis. Global Biogeochemical Cycles, 25(2), GB2008. doi:10.1029/2009GB003769. [Open Access]
• Yamazaki, A., Watanabe, T., Ogawa, N.O., Ohkouchi, N., Shirai, K., Toratani, M., and Uematsu, M. (2011) Seasonal variations in the nitrogen isotope composition of Okinotori coral in the tropical western Pacific: A new proxy for marine nitrate dynamics. Journal of Geophysical Research - Biogeosciences, 116, G04005. doi:10.1029/2011JG001697. [Open Access]
• Zhou, Y., Grice, K., Chikaraishi, Y., Stuart-Williams, H., Farquhar, G.D., and Ohkouchi, N. (2011) Temperature effect on leaf water deuterium enrichment and isotopic fractionation during leaf lipid biosynthesis: Results from controlled growth of C₃ and C₄ land plants. Phytochemistry, 72, 207-213. doi:10.1016/j.phytochem.2010.10.022. [Abstract]

2010

• Chikaraishi, Y., Ogawa, N.O., and Ohkouchi, N. (2010) Further evaluation of the trophic level estimation based on nitrogen isotopic composition of amino acids. Earth, Life, and Isotopes (Eds. Ohkouchi N, Tayasu I, Koba K), Kyoto University Press, pp.37-51. [Open Access]
• Chikaraishi, Y., and Ohkouchi, N. (2010) An improved method for precise determination of carbon isotopic composition of amino acids. Earth, Life, and Isotopes (Eds. Ohkouchi N, Tayasu I, Koba K), Kyoto University Press, pp.355-366.
• Chikaraishi, Y., Takano, Y., Ogawa, N.O., and Ohkouchi, N. (2010) Instrumental optimization of compound-specific nitrogen isotope analysis of amino acids by gas chromatography/combustion/isotope ratio mass spectrometry. Earth, Life, and Isotopes (Eds. Ohkouchi N, Tayasu I, Koba K), Kyoto University Press, pp.367-386. [Open Access]
• Kashiyama, Y., Ogawa, N.O., Chikaraishi, Y., Kashiyama, N., Sakai, S., Tanabe, K., and Ohkouchi, N. (2010) Reconstructing the life history of modern and fossil nautiloids based on the nitrogen isotopic composition of shell organic matter and amino acids. Cephalopods - Present and Past, Tokai University Press, Tokyo, pp.67-75. [Open Access]
• Kashiyama, Y., Ogawa, N.O., Nomoto, S., Kitazato, H., and Ohkouchi, N. (2010) Nitrogen and carbon isotopic compositions of copper, nickel, and vanadyl porphyrins in Cretaceous black shales. Earth, Life, and Isotopes (Eds. Ohkouchi N, Tayasu I, Koba K), Kyoto University Press, pp.313-335. [Open Access]
• Kuroda, J., Hori, R.S., Suzuki, K., Gröcke, D.R., and Ohkouchi, N. (2010) Marine osmium isotope record across the Triassic-Jurassic boundary from a Pacific pelagic site. Geology, 38(12), 1095-1098. doi:10.1130/G31223.1. [Open Access]
• Kusch, S., Kashiyama, Y., Ogawa, N.O., Altabet, M., Butzin, M., Friedrich, J., Ohkouchi, N., and Mollenhauer, G. (2010) Implications for chloro- and pheopigment synthesis and preservation from combined compound-specific δ¹³C, δ¹⁵N, and Δ¹⁴C analysis. Biogeosciences, 7(12), 4105-4118. doi:10.5194/bg-7-4105-2010. [Open Access]
• Naito, Y.I., Chikaraishi, Y., Ohkouchi, N., Mukai, H., Shibata, Y., Honch, N.V., Dodo, Y., Ishida, H., Amano, T., Ono, H., and Yoneda, M. (2010) Dietary reconstruction of the Okhotsk Culture of Hokkaido, Japan, based on nitrogen composition of amino acids: implication for correction of ¹⁴C marine reservoir effects on human bones. Radiocarbon, 52(2), 671-681. doi:10.1017/S0033822200045690. [Open Access]
• Naito, Y.I., Honch, N.V., Chikaraishi, Y., Ohkouchi, N., and Yoneda, M. (2010) Quantitative evaluation of marine protein contribution in ancient diets based on nitrogen isotope ratios of individual amino acids in bone collagen: An investigation at the Kitakogane Jomon site. American Journal of Physical Anthropology, 143(1), 31-40. doi:10.1002/ajpa.21287. [Abstract]
• Nomaki, H., Ogawa, N.O., Ohkouchi, N., Toyofuku, T., and Kitazato, H. (2010) The role of meiofauna in deep-sea benthic food webs revealed by carbon and nitrogen stable isotope analyses. Earth, Life, and Isotopes (Eds. Ohkouchi N, Tayasu I, Koba K), Kyoto University Press, pp.119-138.
• Ogawa, N.O., Nagata, T., Kitazato, H., and Ohkouchi, N. (2010) Ultra-sensitive elemental analyzer/isotope ratio mass spectrometer for stable nitrogen and carbon isotope analyses. Earth, Life, and Isotopes (Eds. Ohkouchi N, Tayasu I, Koba K), Kyoto University Press, pp.339-353. [Open Access]
• Ohkouchi, N., Chikaraishi, Y., Kashiyama, Y., and Ogawa, N.O. (2010) Isotopomers of chlorophyll nuclei: Theories and an application. Earth, Life, and Isotopes (Eds. Ohkouchi N, Tayasu I, Koba K), Kyoto University Press, pp.271-290. [Open Access]
• Sekine, Y., Tajika, E., Ohkouchi, N., Ogawa, N.O., Goto, K., Tada, R., Yamamoto, S., and Kirschvink, J.L. (2010) Anomalous negative excursion of carbon isotope in organic carbon after the last Paleoproterozoic glaciation in North America. Geochemistry Geophysics Geosystems, 11(8), Q08019. doi:10.1029/2010GC003210. [Open Access]
• Takano, Y., Chikaraishi, Y., Ogawa, N.O., Nomaki, H., Morono, Y., Inagaki, F., Kitazato, H., Hinrichs, K.-U., and Ohkouchi, N. (2010) Sedimentary membrane lipids recycled by deep-sea benthic archaea. Nature Geoscience, 3, 858-861. doi:10.1038/ngeo983. [Abstract]
• Takano, Y., Chikaraishi, Y., and Ohkouchi, N. (2010) Enantiomer-specific isotope analysis of D- and L-alanine: Nitrogen isotopic hetero- and homogeneity in microbial and chemical processes. Earth, Life, and Isotopes (Eds. Ohkouchi N, Tayasu I, Koba K), Kyoto University Press, pp.387-402. [Open Access]
• Takano, Y., Kashiyama, Y., Ogawa, N.O., Chikaraishi, Y., and Ohkouchi, N. (2010) Isolation and desalting with cation-exchange chromatography for compound-specific nitrogen isotope analysis of amino acids: application to biogeochemical samples. Rapid Communications in Mass Spectrometry, 24(16), 2317-2323. doi:10.1002/rcm.4651. [Open Access]
• Takano, Y., Yokoyama, Y., Tyler, J.J., Kojima, H., Fukui, M., Sato, T., Ogawa, N.O., Suzuki, N., Kitazato, H., and Ohkouchi, N. (2010) Crustal uplifting rate associated with late-Holocene glacial-isostatic rebound at Skallen and Skarvsnes, Lützow-Holm Bay, East Antarctica: evidence of a synchrony in sedimentary and biological facies on geological setting. Biogeosciences Discuss, 7, 4341-4384. doi:10.5194/bgd-7-4341-2010. [Open Access]
• Tyler, J., Kashiyama, Y., Ohkouchi, N., Ogawa, N.O., Yokoyama, Y., Chikaraishi, Y., Staff, R.A., Ikehara, M., Bronk Ramsey, C., Bryant, C., Brock, F., Gotanda, K., Haraguchi, T., Yonenobu, H., and Nakagawa, T. (2010) Tracking aquatic change using chlorin-specific carbon and nitrogen isotopes: The last glacial-interglacial transition at Lake Suigetsu, Japan. Geochemistry, Geophysics, Geosystems, 11(9), Q09010. doi:10.1029/2010GC003186. [Open Access]
• Yamaguchi, K., Oguri, K., Ogawa, N.O., Sakai, S., Hirano, S., Kitazato, H., and Ohkouchi, N. (2010) Geochemistry of modern carbonaceous sediments overlain by a water mass showing photic zone anoxia in the saline meromictic Lake Kai-ike, southwest Japan: I. Early diagenesis of organic carbon, nitrogen, and phosphorus. Palaeogeography, Palaeoclimatology, Palaeoecology, 294(1-2), 72-82. doi:10.1016/j.palaeo.2009.10.024. [Open Access]
• Yokoyama, Y., Koizumi, M., Matsuzaki, H., Miyairi, Y., and Ohkouchi, N. (2010) Developing ultra small-scale radiocarbon sample measurement at the University of Tokyo. Radiocarbon. 52(2), 310-318. [Open Access]

2009

• Bassez, M.-P., Takano, Y., and Ohkouchi, N. (2009) Organic analysis of peridotite rocks from the Ashadze and Logatchev hydrothermal sites. International Journal of Molecular Sciences, 10(7), 2986-2998. doi:10.3390/ijms10072986. [Open Access]
• Chikaraishi, Y., Ogawa, N.O., Kashiyama, Y., Takano, Y., Suga, H., Tomitani, A., Miyashita, H., Kitazato, H., and Ohkouchi, N. (2009) Determination of aquatic food-web structure based on compound-specific nitrogen isotopic composition of amino acids. Limnology and Oceanography: Methods, 7(11), 740-750. doi:10.4319/lom.2009.7.740. [Open Access]
• Chikaraishi, Y., Tanaka, R., Tanaka, A., and Ohkouchi, N. (2009) Fractionation of hydrogen isotopes during phytol biosynthesis. Organic Geochemistry, 40(5), 569-573. doi:10.1016/j.orggeochem.2009.02.007. [Open Access]
• Nomaki, H., Ohkouchi, N., Heinz, P., Suga, H., Chikaraishi, Y., Ogawa, N.O., Matsumoto, K., and Kitazato, H. (2009) Degradation of algal lipids by deep-sea benthic foraminifera: An in situ tracer experiment. Deep Sea Research Part I: Oceanographic Research Papers, 56(9), 1488-1503. doi:10.1016/j.dsr.2009.04.013. [Open Access]
• Takano, Y., Chikaraishi, Y., Ogawa, N.O., Kitazato, H., and Ohkouchi, N. (2009) Compound-specific nitrogen isotope analysis of D-alanine, L-alanine, and valine: Application of diastereomer separation to δ¹⁵N and microbial peptidoglycan studies. Analytical Chemistry, 81(1), 394-399. doi:10.1021/ac802077v. [Open Access]
• Tejada, M.L.G., Suzuki, K., Kuroda, J., Coccioni, R., Mahoney, J.J., Ohkouchi, N., Sakamoto, T., and Tatsumi, Y. (2009) Ontong Java Plateau eruption as a trigger for the early Aptian oceanic anoxic event. Geology, 37(9), 855-858. doi:10.1130/G25763A.1. [Open Access]

2008

• Chikaraishi, Y., Kashiyama, Y., Ogawa, N.O., Kitazato, H., Satoh, M., Nomoto, S., and Ohkouchi, N. (2008) A compound-specific isotope method for measuring the stable nitrogen isotopic composition of tetrapyrroles. Organic Geochemistry, 39(5), 510-520. doi:10.1016/j.orggeochem.2007.08.010. [Open Access]
• Jenkins, R.G., Hikida, Y., Chikaraishi, Y., Ohkouchi, N., and Tanabe, K. (2008) Microbially induced formation of ooid-like coated grains in the Late Cretaceous methane-seep deposits of the Nakagawa area, Hokkaido, northern Japan. Island Arc, 17(2), 261-269. doi:10.1111/j.1440-1738.2008.00616.x. [Abstract]
• Kashiyama, Y., Miyashita, H., Ohkubo, S., Ogawa, N.O., Chikaraishi, Y., Takano, Y., Suga, H., Toyofuku, T., Nomaki, H., Kitazato, H., Nagata, T., and Ohkouchi, N. (2008) Evidence of global chlorophyll d. Science, 321(5889), pp.658. doi:10.1126/science.1158761. [Abstract]
• Kashiyama, Y., Ogawa, N.O., Kuroda, J., Shiro, M., Nomoto, S., Tada, R., Kitazato, H., and Ohkouchi, N. (2008) Diazotrophic cyanobacteria as the major photoautotrophs during mid-Cretaceous oceanic anoxic events: Nitrogen and carbon isotopic evidence from sedimentary porphyrin. Organic Geochemistry, 39(5), 532-549. doi:10.1016/j.orggeochem.2007.11.010. [Open Access]
• Kashiyama, Y., Ogawa, N.O., Shiro, M., Tada, R., Kitazato, H., and Ohkouchi, N. (2008) Reconstruction of the biogeochemistry and ecology of photoautotrophs based on the nitrogen and carbon isotopic compositions of vanadyl porphyrins from Miocene siliceous sediments. Biogeosciences, 5(3), 797-816. doi:10.5194/bg-5-797-2008. [Open Access]
• Neal, C.R., Coffin, M.F., Arndt, N.T., Duncan, R.A., Eldholm, O., Erba, E., Farnetani, C., Fitton, J.F., Ingle, S.P., Ohkouchi, N., Rampino, M.R., Reichow, M.K., Self, S., and Tatsumi, Y. (2008) Investigatin large igneous province formation and associated paleoenvironmental events: A white paper for scientific drilling. Scientific Drilling, 6, 4-18. doi:10.2204/iodp.sd.6.01.2008. [Open Access]
• Nomaki, H., Ogawa, N.O., Ohkouchi, N., Suga, H., Toyofuku, T., Shimanaga, M., Nakatsuka, T., and Kitazato, H. (2008) Benthic foraminifera as trophic links between phytodetritus and benthic metazoans: carbon and nitrogen isotopic evidence. Marine Ecology Progress Series, 357, 153-164. doi:10.3354/meps07309. [Open Access]
• Ohkouchi, N., and Eglinton, T.I. (2008) Compound-specific radiocarbon dating of Ross Sea sediments: A prospect for constructing chronologies in high-latitude oceanic sediments. Quaternary Geochronology, 3(3), 235-243. doi:10.1016/j.quageo.2007.11.001. [Abstract]
• Ohkouchi, N., Nakajima, Y., Ogawa, N.O., Chikaraishi, Y., Suga, H., Sakai, S., and Kitazato, H. (2008) Carbon isotopic composition of the tetrapyrrole nucleus in chloropigments from a saline meromictic lake: A mechanistic view for interpreting the isotopic signature of alkyl porphyrins in geological samples. Organic Geochemistry, 39(5), 521-531. doi:10.1016/j.orggeochem.2007.11.002. [Open Access]
• Shah, S.R., Mollenhauer, G., Ohkouchi, N., Eglinton, T.I., and Pearson, A. (2008) Origins of archaeal tetraether lipids in sediments: Insights from radiocarbon analysis. Geochimica et Cosmochimica Acta, 72(18), 4577-4594. doi:10.1016/j.gca.2008.06.021. [Open Access]
• Suzuki, Y., Chikaraishi, Y., Ogawa, N.O., Ohkouchi, N., and Korenaga, T. (2008) Geographical origin of polished rice based on multiple element and stable isotope analyses. Food Chemistry, 109(2), 470-475. doi:10.1016/j.foodchem.2007.12.063. [Abstract]

2007

• Chikaraishi, Y., Kashiyama, Y., Ogawa, N.O., Kitazato, H., and Ohkouchi, N. (2007) Metabolic control of nitrogen isotopic composition of amino acids in macroalgae and gastropods: implications for aquatic food web studies. Marine Ecology Progress Series, 342, 85-90. doi:10.3354/meps342085. [Open Access]
• Chikaraishi, Y., Matsumoto, K., Kitazato, H., and Ohkouchi, N. (2007) Sources and transformation processes of pheopigments: Stable carbon and hydrogen isotopic evidence from Lake Haruna, Japan. Organic Geochemistry, 38(6), 985-1001. doi:10.1016/j.orggeochem.2007.01.005. [Open Access]
• Kashiyama, Y., Kitazato, H., and Ohkouchi, N. (2007) An improved method for isolation and purification of sedimentary porphyrins by high-performance liquid chromatography for compound-specific isotopic analysis. Journal of Chromatography A, 1138(1-2), 73-83. doi:10.1016/j.chroma.2006.10.028. [Abstract]
• Kashiyama, Y., Shiro, M., Tada, R., and Ohkouchi, N. (2007) A novel vanadyl alkylporphyrins from geological samples: A possible derivative of divinylchlorophylls or bacteriochlorophyll a? Chemistry Letters, 36(6), 706-707. doi:10.1246/cl.2007.706. [Abstract]
• Kuroda, J., Ogawa, N.O., Tanimizu, M., Coffin, M.F., Tokuyama, H., Kitazato, H., and Ohkouchi, N. (2007) Contemporaneous massive subaerial volcanism and late Cretaceous Oceanic Anoxic Event 2. Earth and Planetary Science Letters, 256(1-2), 211-223. doi:10.1016/j.epsl.2007.01.027. [Open Access]

2006

• Kameo, K., Okada, M., El-Masry, M., Hisamitsu, T., Saito, S., Nakazato, H., Ohkouchi, N., Ikehara, M., Yasuda, H., Kitazato, H., and Taira, A. (2006) Age model, physical properties and paleoceanographic implications of the middle Pleistocene core sediments in the Choshi area, central Japan. Island Arc, 15(3), 366-377. doi:10.1111/j.1440-1738.2006.00535.x. [Abstract]
• Kuroda, J., and Ohkouchi, N. (2006) Implications of spatiotemporal distribution of black shales deposited during the Cretaceous Oceanic Anoxic Event-2. Paleontological Research, 10(4), 345-358. doi:10.2517/prpsj.10.345. [Open Access]
• Nomaki, H., Heinz, P., Nakatsuka, T., Shimanaga, M., Ohkouchi, N., Ogawa, N.O., Kogure, K., Ikemoto, E., and Kitazato, H. (2006) Different ingestion patterns of ¹³C-labeled bacteria and algae by deep-sea benthic foraminifera. Marine Ecology Progress Series, 310, 95-108. doi:10.3354/meps310095. [Open Access]
• Ohkouchi, N., and Eglinton, T.I. (2006) Radiocarbon constraint on relict organic carbon contributions to Ross Sea sediments. Geochemistry, Geophysics, Geosystems, 7(4), Q04012. doi:10.1029/2005GC001097. [Open Access]
• Ohkouchi, N., Kashiyama, Y., Kuroda, J., Ogawa, N.O., and Kitazato, H. (2006) The importance of diazotrophic cyanobacteria as primary producers during Cretaceous Oceanic Anoxic Event 2. Biogeosciences, 3(4), 467-478. doi:10.5194/bg-3-467-2006. [Open Access]
• Yokoyama, Y., Naruse, T., Ogawa, N.O., Tada, R., Kitazato, H., and Ohkouchi, N. (2006) Dust influx reconstruction during the last 26,000 years inferred from a sedimentary leaf wax record from Japan Sea. Global and Planetary Change, 54(3-4), 239-250. doi:10.1016/j.gloplacha.2006.06.022. [Open Access]

2005

• Chikaraishi, Y., Matsumoto, K., Ogawa, N.O., Suga, H., Kitazato, H., and Ohkouchi, N. (2005) Hydrogen, carbon and nitrogen isotopic fractionations during chlorophyll biosynthesis in C3 higher plants. Phytochemistry, 66(8), 911-920. doi:10.1016/j.phytochem.2005.03.004. [Abstract]
• Kuroda, J., Ohkouchi, N., Ishii, T., Tokuyama, H., and Taira, A. (2005) Lamina-scale analysis of sedimentary components in Cretaceous black shales by chemical compositional mapping: Implications for paleoenvironmental changes during the Oceanic Anoxic Events. Geochimica et Cosmochimica Acta, 69(6), 1479-1494. doi:10.1016/j.gca.2004.06.039. [Open Access]
• Ohkouchi, N., Eglinton, T.I., Hughen, K.A., Roosen, E., and Keigwin, L.D. (2005) Radiocarbon dating of alkenones from marine sediments: III. Influence of solvent extraction procedures on ¹⁴C measurements of foraminifera. Radiocarbon, 47(3), 425-432. [Open Access]
• Ohkouchi, N., Nakajima, Y., Okada, H., and Kitazato, H. (2005) Copper-chelated bacteriochlorophyll e homologues in sediment from an anoxic lake (Lake Abashiri, Japan). Organic Geochemistry, 36(11), 1576-1580. doi:10.1016/j.orggeochem.2005.08.003. [Open Access]
• Ohkouchi, N., Nakajima, Y., Okada, H., Ogawa, N.O., Suga, H., Oguri, K., and Kitazato, H. (2005) Biogeochemical processes in the saline meromictic Lake Kaiike, Japan: implications from molecular isotopic evidences of photosynthetic pigments. Environmental Microbiology, 7(7), 1009-1016. doi:10.1111/j.1462-2920.2005.00772.x. [Abstract]
• Ohkouchi, N., Xu, L., Reddy, C.M., Montluçon, D., and Eglinton, T.I. (2005) Radiocarbon dating of alkenones from marine sediments: I. Isolation protocol. Radiocarbon, 47(3), 401-412. [Open Access]

2004

• Nakajima, Y., Shimizu, H., Ogawa, N.O., Sakamoto, T., Okada, H., Koba, K., Kitazato, H., and Ohkouchi, N. (2004) Vertical distributions of stable isotopic compositions and bacteriochlorophyll homologues in suspended particulate matter in saline meromictic Lake Abashiri. Limnology, 5(3), 185-189. doi:10.1007/s10201-004-0125-6. [Abstract]

2003

• Johnson, C.G., Frysinger, G.S., Nelson, R.K., Gaines, R.B., Ohkouchi, N., Reddy, C.M., and Eglinton, T.I. (2003) Innovative methods for determining alkenone unsaturation indices. Marine Chemistry, 83(1-2), 5-22. doi:10.1016/S0304-4203(03)00092-6. [Open Access]
• Mollenhauer, G., Eglinton, T.I., Ohkouchi, N., Schneider, R.R., Müller, P.J., Grootes, P.M., and Rullkötter, J. (2003) Asynchronous alkenone and foraminifera records from the Benguela Upwelling System. Geochimica et Cosmochimica Acta, 67(12), 2157-2171. doi:10.1016/S0016-7037(03)00168-6. [Open Access]
• Nakajima, Y., Okada, H., Oguri, K., Suga, H., Kitazato, H., Koizumi, Y., Fukui, M., and Ohkouchi, N. (2003) Distribution of chloropigments in suspended particulate matter and benthic microbial mat of a meromictic lake, Lake Kaiike, Japan. Environmental Microbiology, 5(11), 1103-1110. doi:10.1046/j.1462-2920.2003.00517.x. [Abstract]
• Ohkouchi, N., Eglinton, T.I., and Hayes, J.M. (2003) Radiocarbon dating of individual fatty acids as a tool for refining Antarctic margin sediment chronologies. Radiocarbon, 45(1), 17-24. [Open Access]

2002

• Ohkouchi, N., Eglinton, T.I., Keigwin, L.D., and Hayes, J.M. (2002) Spatial and temporal offsets between proxy records in a sediment drift. Science, 298(5596), 1224-1227. doi:10.1126/science.1075287. [Abstract]
• Pagani, M., Freeman, K.H., Ohkouchi, N., and Caldeira, K. (2002) Comparison of water column [CO_2aq] with sedimentary alkenone-based estimates: A test of the alkenone-CO₂ proxy. Paleoceanography, 17(4), PA000756. doi:10.1029/2002PA000756. [Open Access]

2001

• Ogawa, N.O., Koitabashi, T., Oda, H., Nakamura, T., Ohkouchi, N., and Wada, E. (2001) Fluctuations of nitrogen isotope ratio of gobiid fish (Isaza) specimens and sediments in Lake Biwa, Japan, during the 20th century. Limnology and Oceanography, 46(5), 1228-1236. doi:10.4319/lo.2001.46.5.1228. [Open Access]
• Rosell-Melé, A., Bard, E., Emeis, K.-C., Grimalt, J.O., Müller, P., Schneider, R., Bouloubassi, I., Epstein, B., Fahl, K., Fluegge, A., Freeman, K., Goñi, M., Güntner, U., Hartz, D., Hellebust, S., Herbert, T., Ikehara, M., Ishiwatari, R., Kawamura, K., Kenig, F., de Leeuw, J., Lehman, S., Mejanelle, L., Ohkouchi, N., Pancost, R.D., Pelejero, C., Prahl, F., Quinn, J., Rontani, J.-F., Rostek, F., Rullkötter, J., Sachs, J., Blanz, T., Sawada, K., Schults-Bull, D., Sikes, E., Sonzogni, C., Ternois, Y., Versteegh, G., Volkman, J.K., and Wakeham, S. (2001) Precision of the current methods to measure the alkenone proxy U₃₇K' and absolute alkenone abundance in sediments: Results of an interlaboratory comparison study. Geochemistry, Geophysics, Geosystems, 2(7), Paper number 2000GC000141. doi:10.1029/2000GC000141. [Open Access]
• Ternois, Y., Kawamura, K., Keigwin, L., Ohkouchi, N., and Nakatsuka, T. (2001) A biomarker approach for assessing marine and terrigenous inputs to the sediments of Sea of Okhotsk for the last 27,000 years. Geochimica et Cosmochimica Acta, 65(5), 791-802. doi:10.1016/S0016-7037(00)00598-6. [Open Access]

2000

• Ikehara, M., Kawamura, K., Ohkouchi, N., Murayama, M., Nakamura, T., and Taira, A. (2000) Variations of terrestrial input and marine productivity in the Southern Ocean (48°S) during the last two deglaciations. Paleoceanography, 15(2), 170-180. doi:10.1029/1999PA000425. [Open Access]
• Ohkouchi, N., Kawamura, K., Takemoto, N., Ikehara, M., and Nakatsuka, T. (2000) Implications of carbon isotope ratios of C₂₇-C₃₃ alkanes and C₃₇ alkenes for the sources of organic matter in the southern ocean surface sediments. Geophysical Research Letters, 27(2), 233-236. doi:10.1029/1999GL002351. [Open Access]
• Prahl, F., Herbert, T., Brassell, S.C., Ohkouchi, N., Pagani, M., Repeta, D., Rosell-Melé, A., and Sikes, E. (2000) Status of alkenone paleothermometer calibration: Report from Working group 3. Geochemistry, Geophysics, Geosystems, 1(11), Paper number 2000GC000058. doi:10.1029/2000GC000058. [Open Access]
• Ternois, Y., Kawamura, K., Ohkouchi, N., and Keigwin, L. (2000) Alkenone sea surface temperature in the Okhotsk Sea for the last 15 kyr. Geochemical Journal, 34(4), 283-293. doi:10.2343/geochemj.34.283. [Open Access]

1994-1999

• Ikehara, M., Kawamura, K., Ohkouchi, N., and Taira, A. (1999) Organic geochemistry of greenish clay and organic-rich sediments since the early Miocene from Hole 985A, Norway Basin. Proceedings of Ocean Drilling Program, Scientific Results, 162, 209-216. doi:10.2973/odp.proc.sr.162.020.1999. [Open Access]
• Ohkouchi, N., Kawamura, K., and Kawahata, H. (1999) Distributions of three- to seven-ring polynuclear aromatic hydrocarbons on the deep sea floor in the central Pacific. Environmental Science and Technology, 33(18), 3086-3090. doi:10.1021/es981181w. [Abstrat]
• Ohkouchi, N., Kawamura, K., Kawahata, H., and Okada, H. (1999) Depth ranges of alkenone production in the central Pacific Ocean. Global Biogeochemical Cycles, 13(2), 695-704. doi:10.1029/1998GB900024. [Open Access]
• Ohkouchi, N., Kawamura, K., Kajiwara, Y., Wada, E., Okada, M., Kanamatsu, T., and Taira, A. (1999) Sulfur isotope records around Livello Bonarelli (northern Apennines, Italy) black shale at the Cenomanian-Turonian boundary. Geology, 27(6), 535-538. doi:10.1130/0091-7613. [Abstract]
• Ikehara, M., Kawamura, K., Ohkouchi, N., Kimoto, K., Murayama, M., Nakamura, T., Oba, T., and Taira, A. (1997) Alkenone sea surface temperature in the Southern Ocean for the last two deglaciations. Geophysical Research Letters, 24(6), 679-682. doi:10.1029/97GL00429. [Open Access]
• Ohkouchi, N., Kawamura, K., Kawahata, H., and Taira, A. (1997) Latitudinal distributions of terrestrial biomarkers in the sediments from the Central Pacific. Geochimica et Cosmochimica Acta, 61(9), 1911-1918. doi:10.1016/S0016-7037(97)00040-9. [Open Access]
• Ohkouchi, N., Kawamura, K., and Taira, A. (1997) Fluctuations of terrestrial and marine biomarkers in the western tropical Pacific during the last 23,300 years. Paleoceanography, 12(4), 623-630. doi:10.1029/97PA00820. [Open Access]
• Ohkouchi, N., Kawamura, K., and Taira, A. (1997) Molecular paleoclimatology: reconstruction of climate variabilities in the late Quaternary. Organic Geochemistry, 27(3-4), 173-183. doi:10.1016/S0146-6380(97)00080-6. [Open Access]
• Ohkouchi, N., Kawamura, K., Wada, E., and Taira, A. (1997) High abundances of hopanols and hopanoic acids in Cretaceous black shales. Ancient Biomolecules, 1, 183-192.
• Ohkouchi, N., and Wada, E. (1997) Secular variations in sedimentary organic δ¹³C during the last 35 M.Y. in the tropical Atlantic, Site 925. Proceedings of Ocean Drilling Program Scientific Results, 154, 501-505. [Open Access]
• Ohkouchi, N., Kawahata, H., Okada, M., Murayama, M., Matsumoto, E., Nakamura, T., and Taira, A. (1995) Benthic foraminifera cadmium record from the western equatorial Pacific. Marine Geology, 127(1-4), 167-180. doi:10.1016/0025-3227(95)00009-N. [Open Access]
• Ohkouchi, N., Kawamura, K., Kawahata, H., and Taira, A. (1995) Organic geochemistry of deep sea sediments: how it contributes to paleoceanography. in Global Fluxes of Carbon and Its Related Substances in the Coastal Sea-Ocean-Atmosphere System, pp.533-538.
• Ohkouchi, N., Kawahata, H., Murayama, M., Okada, M., Nakamura, T., and Taira, A. (1994) Was deep water formed in the North Pacific during the Late Quaternary? Cadmium evidence from the Northwest Pacific. Earth and Planetary Science Letters, 124(1-4), 185-194. doi:10.1016/0012-821X(94)00082-4. [Open Access]
• Ohkouchi, N., Kawamura, K., Nakamura, T., and Taira, A. (1994) Small changes in the sea surface temperature during the last 20,000 years: Molecular evidence from the western tropical Pacific. Geophysical Research Letters, 21(20), 2207-2210. doi:10.1029/94GL01991. [Abstract]

---

---

Books and Reviews

• Ohkouchi, N. (2017) Development of sediment chronologies with amino acid radiocarbon dating. Impact, 2017(11), 33-35. doi:10.21820/23987073.2017.11.33. [Open Access]
• Bickle, M., Arculus, R., Barrett, P., DeConto, R., Camoin, G., Edwards, K., Fisher, F., Inagaki, F.,Kodaira, S., Ohkouchi, N., Palike, H., Ravelo, C., Saffer, D., and Teagle, D. (2011) Illuminating Earth’s Past, Present and Future. The International Ocean Discovery Program, Science Plan for 2013-2023, 84pp. [IODP Science Plan]
• Ohkouchi, N., Tayasu, I., and Koba, K. (eds.) (2010) Earth, Life, and Isotopes. Kyoto University Press.
• Fukao, Y., Kodaira, S., Kinoshita, M., Tatsumi, Y., Ohkouchi, N., Suzuki, K., Suetsugu, D., Hanyu, T., Sugioka, H., Ono, S., Hirose, K., Yanagisawa, T., Hamano, Y., Fujiwara, T., Kitazato, H., Takahashi, N., and Sakaguchi, H. (2009) Review of five years of activity at IFREE /JAMSTEC. JAMSTEC Report of Research and Development, 9(2), 43-94. [Open Access]
• Ogawa, N.O., Sato, R., and Ohkouchi, N. (2006) Evaluation of precision and accuracy for carbon isotopic measurements of ¹³C-labeled samples by an on line elemental analyzer / isotope ratio mass spectrometer system. Frontier Research on Earth Evolution, Vol.2. [PDF]
• Ohkouchi, N., Nakajima, Y., Ogawa, N.O., Suga, H., Kashiyama, Y., Matsumoto, K., Chikaraishi, Y., Oguri, K., and Kitazato, H. (2006) Stable carbon and nitrogen isotopic compositions of photosynthetic pigments as tracers for elemental cycle in the modern- and paleo-environments. Frontier Research on Earth Evolution, Vol.2. [PDF]
• Ohkouchi, N., Yanagisawa, T., Kuroda, J., Yamagishi, Y., Hamano, Y., Tanimizu, M., Ogawa, N.O., Suganuma, Y., and Yoshihara, A. (2006) A status report of MUD “Global Event” group: A dynamic interaction between Earth’s interior and surface environments in the mid Cretaceous. Frontier Research on Earth Evolution, Vol.2. [PDF]
• Ohkouchi, N., Kuroda, J., Okada, M., and Tokuyama, H. (2003) Why Cretaceous black shales have high C/N ratios: Implications from SEM-EDX observations for Livello Bonarelli black shales at Cenomanian-Turonian boundary. Frontier Research on Earth Evolution, Vol.1, 239-241. [PDF]
• Kajiwara, Y., Kaiho, K., and Ohkouchi, N. (1997) An invitation to the sulfur isotope study of marine sediments: implications and constraints for the exogenic sulfur cycle. Annual Report of Institute of Geoscience, University of Tsukuba, 23, 69-74.