小畑　元 obata(a)aori.u-tokyo.ac.jp
教授・博士(理学)


東京大学大気海洋研究所
海洋化学部門・海洋無機化学分野
〒277-8564　千葉県柏市柏の葉5-1-5

海洋における微量元素の分布、存在状態を調べ、その循環過程に関わる化学的、生物学的、物理学的要因を解析する。特に鉄やアルミニウム、白金などの微量金属元素を対象とする。また、海水中の微量元素についての高感度分析法も併行して開発している。

これまでの主な研究テーマ

●海洋における微量金属元素の分布と物質循環の解明

●海水中微量金属元素の存在状態の解明

●海水中微量金属元素(鉄、アルミニウム、マンガンなど)の高感度自動分析法の開発

●電気分析化学的手法の海洋への適用

経歴

1997年3月　京都大学大学院理学研究科化学専攻において博士(理学)取得

1997年4月　日本学術振興会特別研究員(PD, 滋賀県立大学環境科学部)

1999年1月　東京大学海洋研究所COE研究員

2000年2月　日本学術振興会海外特別研究員(University of Liverpool, UK)

2001年6月　東京大学海洋研究所助手

2003年4月　東京大学海洋研究所講師

2007年4月　東京大学海洋研究所准教授

2010年4月　東京大学大気海洋研究所准教授

2017年12月　東京大学大気海洋研究所教授

 

所属学会

●日本海洋学会

●日本地球化学会 （「地球化学」編集委員長, 2018-）

●日本分析化学会

●American Geophysical Union

●American Society of Limnology and Oceanography

著書

●「海と湖の化学」　微量元素で探るー(共著, 京都大学学術出版会, 2005)

●地球化学講座第6巻 「大気・水圏の地球化学」(共著, 培風館, 2005)

 
Publication List (2001-)

Okubo, A., H. Obata, T. Gamo and M. Yamada. ²³⁰Th and ²³²Th distributions in mid-latitudes of the North Pacific Ocean: effect of bottom scavenging and lateral transport. Earth and Planetary Science Letters, in press.

Kawagucci, S., Y. Ueno, K. Takai, T. Toki, M. Ito, K. Inoue, A. Makabe, N. Yoshida, Y. Muramatsu, N. Takahata, Y. Sano, T. Narita, G. Teranishi, H. Obata, S. Nakagawa, T. Nunoura, and T. Gamo. Geochemical origin of hydrothermal fluid methane in sediment-associated fields and its relevance to the geographical distribution of whole hydrothermal circulation. Chemical Geology, in press.

van de Flierdt, T., Pahnke, K., and GEOTRACES intercalibration participants (H. Amakawa, P. Andersson, C. Basak, B. Coles, C. Colin, K. Crocket, M. Frank, N. Frank, S. L. Goldstein, V. Goswami, B. A. Haley, E. C. Hathorne, S. R. Hemming, G. M. Henderson, C. Jeandel, K. Jones, K. Kreissig, F. Lacan, M. Lambelet1, E. E. Martin, D. R. Newkirk, H. Obata, L. Pena, A. M. Piotrowski, C. Pradoux, H. D. Scher, H. Schöberg, S. K. Singh, T. Stichel, H. Tazoe, D. Vance, J. Yang). GEOTRACES intercalibration of neodymium isotopes and rare earth element concentrations in seawater and suspended particles – Part 1: reproducibility of results for the international intercomparison. Limnology and Oceanography Method, in press.

Maruo, M. and H. Obata, 2011. Unique elution behavior of bromide and nitrate in anion-exchange chromatography using aqueous potassium chloride eluent containing cadmium or zinc ion. Analytical Sciences, 27: 949-951.

Kawagucci, S., H. Chiba, J. Ishibashi, T. Yamanaka, T. Toki, Y. Muramatsu, Y. Ueno, A. Makabe, K. Inoue, N. Yoshida, S. Nakagawa, T. Nunoura, K. Takai, N. Takahata, Y. Sano, T. Narita, G. Teranishi, H. Obata, and T. Gamo, 2011. Hydrothermal fluid geochemistry at the Iheya North field in the mid-Okinawa Trough: Implication for origin of methane in subseafloor fluid circulation systems. Geochemical Journal, 45(2): 109-124.

Tazoe, H., H. Obata, and T. Gamo, 2011. Coupled isotopic systematics of surface cerium and neodymium in the Pacific Ocean. Geochemistry, Geophysics, Geosystems, 12: Q04004, doi:10.1029/2010GC003342.

Gamo, T., U. Tsunogai, S. Ichibayashi, H. Chiba, H. Obata, T. Oomori, T. Noguchi, E. T. Baker, T. Doi, M. Maruo and Y. Sano, 2010. Microbial carbon isotope fractionation to produce extraordinarily heavy methane in aging hydrothermal plumes over the southwestern Okinawa Trough. Geochemical Journal, 44(6): 477-487.

Kameyama, S., H. Tanimoto, S. Inomata, U. Tsunogai, A. Ooki, Y. Yokouchi, S. Takeda, H. Obata, and M. Uematsu, 2010. High-resolution measurement of multiple volatile organic compounds dissolved in seawater using equilibrator inlet-proton transfer reaction-mass spectrometry (EI-PTR-MS). Marine Chemistry, 122(1-4): 59-73.

Maruo, M., K. Tate, K. Ohta, K. Hayakawa, and H. Obata, 2010. Vertical distribution of iron(II) and its relation to organic substances in Lake Biwa, Japan. Verhandlungen Internationale Vereinigung für theoretische und angewandte Limnologie, 30(9): 1379-1383.

Kameyama, S., H. Tanimoto, S. Inomata, U. Tsunogai, A. Ooki, Y. Yokouchi, S. Takeda, H. Obata, and M. Uematsu, 2009. Equilibrator inlet-proton transfer reaction-mass spectrometry (EI-PTR-MS) for sensitive, high-resolution measurement of dimethyl sulfide dissolved in seawater. Analytical Chemistry, 81(21): 9021-9026.

Hara, Y., H. Obata, T. Doi, Y. Hongo, T. Gamo, S. Takeda, and A. Tsuda, 2009. Rare earth elements in seawater during the iron-induced phtoplankton bloom of the western subarctic Pacific (SEEDS-II). Deep-Sea Research-II, 56: 2839-2851.

Nishioka, J., S. Takeda, Y. Kondo, H. Obata, T. Doi, D. Tsumune, C.S. Wong, W.K. Johnson, and A. Tsuda, 2009. Changes in iron concentrations and bio-availability during an open ocean mesoscale iron enrichment in the western subarctic Pacific, SEEDS II. Deep-Sea Research-II, 56: 2796-2809.

Oka, A., H. Hasumi, H. Obata, T. Gamo, and Y. Yamanaka, 2009. Study on vertical profiles of rare earth elements by using an ocean general circulation model. Global Biogeochemical Cycles, 23: GB4025, doi:10.1029/2008GB003353.

Ozaki, H., H. Obata, M. Naganobu, and T. Gamo. Long-term bottom water warming in the North Ross Sea, 2009. Journal of Oceanography, 65: 235-244.

Kondo, Y., S. Takeda, J. Nshioka, H. Obata, K. Furuya, W. K. Johonson and C. S. Wong, 2008. Organic iron (III) complexing ligands during an iron enrichment experiment in the western subarctic North Pacific. Geophysical Research Letters, 35: L12601, doi:10.1029/2008GL033354.

Zhang, Y., H. Obata, and T. Gamo, 2008. Silver in the Tokyo Bay estuarine waters and Japanese rivers. Journal of Oceanography, 64: 259-265.

Obata H., K. Shitashima, K. Isshiki, and E. Nakayama, 2008. Iron, manganese and aluminum in upper waters of the western South Pacific Ocean and its adjacent seas. Journal of Oceanography, 64: 233-245.

Obata, H., D.S. Alibo, and Y. Nozaki, 2007. Dissolved aluminum, indium and cerium in the Japan Sea and the Sea of Okhotsk: Comparison to the marginal seas of the western North Pacific. Journal of Geophysical Research-Ocean, 112: C12003, doi:10.1029/2006JC003944.

Tsuda, A., S. Takeda, H. Saito, J. Nishioka, I. Kudo, Y. Nojiri, K. Suzuki, M. Uematsu, M.L. Wells., D. Tsumune, T. Yoshimura, T. Aono, T. Aramaki, W.P. Cochlan, M. Hayakawa, K. Imai, T. Isada, Y. Iwamoto, W.K. Johnson, S. Kameyama, S. Kato, H. Kiyosawa, Y. Kondo, M. Levasseur, R. Machida, I. Nagao, F. Nakagawa, T. Nakanishi, S. Nakatsuka, A. Narita, Y. Noiri, H. Obata, H. Ogawa, K. Oguma, T. Ono, T. Sakuragi, M. Sasakawa, M. Sato, A. Shimamoto, H. Takada, C.G. Trick, Y.W. Watanabe, C.S. Wong, and N. Yoshie, 2007. Evidence for the grazing hypothesis: Grazing reduces phytoplankton responses of the HNLC ecosystem to iron enrichment in the western subarctic Pacific (SEEDS II). Journal of Oceanography, 63(6): 983-994.

Nakayama, N., H. Obata, and T. Gamo, T., 2007. Consumption of dissolved oxygen in the deep Japan Sea, giving a precise isotopic fractionation factor. Geophysical Research Letters, 34(20): L20604, doi:10.1029/2007GL029917.

Okubo, A., H. Obata, S. Luo, T. Gamo, H. Minami, and M. Yamada, 2007. Particle flux in the twilight zone of the eastern Indian Ocean: a constraint from ²³⁴U-²³⁰Th and ²²⁸Ra-²²⁸Th disequilibrium. Deep-Sea Research I, 54(10): 1758-1772.

Tazoe, H., H. Obata, and T. Gamo, 2007. Precise determination of cerium isotopes in geochemical samples using oxidative extraction with chelating resin. Journal of Analytical Atomic Spectrometry, 22: 616-622.

Okubo, A., H. Obata, T. Gamo, H. Minami, and M. Yamada, 2007. Scavenging of ²³⁰Th in the Sulu Sea. Deep-Sea Research II, 54: 50-59.

Obata, H., T.  Doi, Y. Hongo, D.S. Alibo, H. Minami, Y. Kato, and M. Maruo, 2007. Manganese, cerium, and iron in the Philippine, Celebes, and Sulu Seas. Deep-Sea Research II, 54: 38-49.

Hongo, Y., H. Obata, T. Gamo, M. Nakashima, J. Ishibashi, U. Konno, S. Saegusa, S. Ohkubo and U. Tsunogai, 2007. Rare earth elements in the hydrothermal system at Okinawa Trough back-arc basin. Geochemical Journal, 41: 1-15.

Tazoe, H., H. Obata, H. Amakawa, Y. Nozaki, and T. Gamo, 2007. Precise determination of the cerium isotopic composition of surface water in the Northwest Pacific Ocean and Tokyo Bay. Marine Chemistry, 103: 1-14.

Obata, H., T. Yoshida, and H. Ogawa, 2006. Determination of picomolar levels of platinum in estuarine waters: a comparison of cathodic stripping voltammetry and isotope dilution-inductively coupled plasma mass spectrometry. Analytica Chimica Acta, 580: 32-38.

Maruo, M., T. Doi and H. Obata, 2006. Onboard determination of submicromolar nitrate in seawater by anion-exchange chromatography with lithium chloride eluent. Analytical Sciences, 22: 1175-1178.

Hongo, Y, H. Obata, D.S. Alibo and Y. Nozaki, 2006. Spatial variations of rare earth elements in North Pacific surface water. Journal of Oceanography, 62: 441-455.

Zhang, Y., H. Obata and Y. Nozaki, 2004. Silver in the Pacific Ocean and the Bering Sea. Geochemical Journal, 38(6): 623-633.

Gamo, T., H. Masuda, T. Yamanaka, K. Okamura, J. Ishibashi, E. Nakayama, H. Obata, K. Shitashima, Y. Nishio, H. Hasumoto, M. Watanabe, K. Mitsuzawa, N. Seama, U. Tsunogai, F. Kouzuma and Y. Sano, 2004. Discovery of a new hydrothermal venting site in the southernmost Mariana Arc: Al-rich hydrothermal plumes and white smoker activity associated with biogenic methane. Geochemical Journal, 38(6): 527-534.

Okubo, A., H. Obata, Y. Yamamoto and Y. Nozaki, 2004. ²³⁰Th in the Andaman Sea: Rapid renewal. Geophysical Research Letters, 31: L22306, doi:1029/2004GL020226.

Doi, T., H. Obata and M. Maruo, 2004. Shipboard analysis of picomolar levels of manganese in seawater by chelating resin concentration and chemiluminescence detection. Analytical and Bioanalytical Chemistry, 378: 1288-1293.

Obata, H., Y. Nozaki, D. S. Alibo and Y. Yamamoto, 2004. Dissolved Al, In and Ce in the eastern Indian Ocean and the Southeast Asian Seas in comparison with the radionuclides ²¹⁰Pb and ²¹⁰Po. Geochimica et Cosmochimica Acta, 68(5):1035-1048.

Suzuki, K., H. Liu, T. Saino, H. Obata, M. Takano, K. Okamura, Y. Sohrin and Y. Fujishima, 2002. East-west gradients in the photosynthetic potential of phytoplankton and iron concentration in the subarctic Pacific Ocean during early summer. Limnology and Oceanography, 47(6): 1581-1594.

Okamura, K., H. Kimoto, K. Saeki, J. Ishibashi, H. Obata, M. Maruo, T. Gamo, E. Nakayama and Y. Nozaki, 2001.  Development of a deep-sea in situ Mn analyzer and its application for hydrothermal plume observation. Marine Chemistry, 76: 17-26.

Okamura, K., M. Sugiyama, H. Obata, M. Maruo, E. Nakayama, H. Karatani, 2001. Automated determination of vanadium(IV) and -(V) in natural waters based on chelating resin separation and catalytic detection with Bindschedler's green leuco base. Analytica Chimica Acta, 443: 143-151.

Obata, H. and C. M. G. van den Berg, 2001. Determination of picomolar levels of iron in seawater using catalytic cathodic stripping voltammetry. Analytical Chemistry, 73: 2522-2528.

Maruo, M., E. Nakayama, H. Obata, K. Kamiyama and T. Kimoto, 2001. Application of the flow-through analyses of ammonia and calcium in ice core and fresh water by fluorometric detection. Field Analytical Chemistry and Technology, 5: 29-36.

 
「大学院生募集中！」
　海洋無機化学分野では海洋・化学に興味があり、意欲のある大学院生を募集しています。海洋無機化学分野には、東京大学大学院理学系研究科化学専攻、農学生命科学研究科水圏生物科学専攻、新領域創成科学研究科自然環境学専攻を通じて入学することができます。詳しい情報のほしい方は、小畑(obata＠aori.u-tokyo.ac.jp)までお知らせ下さい。

　　　　　　　　　　　　　　　　　　　　　　　　閉じる