教員紹介 – 小畑　元

2018.09.05

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

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 東京大学大気海洋研究所

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 (2010-)

  1. Yamashita, Y., J. Nishioka, H. Obata and H. Ogawa, 2020. Shelf humic substances as carriers for basin-scale iron transport in the North Pacific. Scientific Reports, 10, 4505.
  2. Mashio, A.S., H. Obata, T. Shimazaki, H. Fukuda and H. Ogawa, 2020. Spatiotemporal variations of platinum in seawater in Otsuchi Bay, Japan after the 2011 tsunami. Science of The Total Environment, 708, 134659.
  3. Escobar, Ma. Teresa, N. Takahata, H. Obata and Yuji Sano, 2020. Observation of the deep Indonesian throughflow using helium isotopes. Journal of Oceanography, doi: 10.1007/s10872-020-00560-8.
  4. Nishioka, J., H. Obata, H. Ogawa, K. Ono, Y. Yamashita, K. Lee, S. Takeda and I. Yasuda, 2020. Subpolar marginal seas fuel the North Pacific through the intermediate water at the termination of the global ocean circulation. Proceedings of the National Academy of Sciences of the United States of America, 117(23), 12665 – 12673.
  5. Miwa, K., H. Obata and T. Suzuki, 2020. Vertical distributions of Iodine-129 and iodide in the Chukchi Sea and Bering Sea. Journal of Nuclear Science and Technology, 57(5), 537 – 545.
  6. Tazoe, H., T. Yamagata, K. Tsujita, H. Nagai, H. Obata, D. Tsumune, J. Kanda and M. Yamada, 2019. Observation of dispersion in the Japanese coastal area of released 90Sr, 134Cs, and 137Cs from the Fukushima Daiichi Nuclear Power Plant to the sea in 2013. International Journal of Environmental Research and Public Health, 16(21), 4094 – 4094.
  7. Murakami-Sugihara, Naoko, K. Shirai, M. Hori, Y. Amano, H. Fukuda, H. Obata, K. Tanaka, K. Mizukawa, Y. Sano, H. Takada and H. Ogawa, 2019. Mussel shell geochemical analyses reflect coastal environmental changes following the 2011 Tohoku tsunami. ACS Earth and Space Chemistry, 3, 1346 – 1352.
  8. Sieber M., T.M. Conway, G.F. de Souza, H. Obata, S. Takano, Y. Sohrin and D. Vance, 2019. Physical and biogeochemical controls on the distribution of dissolved cadmium and its isotopes in the Southwest Pacific Ocean. Chemical Geology, 511,494 – 509.
  9. Grand, M. Maxime, A. Laes-Huon, S. Fietz, J.A. Resing, H. Obata, G.W. Luther III, A. Tagliabue, E.P. Achterberg, R. Middag, A. Tovar-Sánchez and A.R. Bowie, 2019. Developing autonomous observing systems for micronutrient trace metals. Frontiers in Marine Science, 6(35), 1 – 17.
  10. 辻 一真, 丸尾 雅啓, 小畑 元 , 2019. イオンクロマトグラフィーによる天然水中極微量メチルホスホン酸の定量. 分析化学, 68(4), 275 – 278.
  11. Escobar, Ma Teresa, N. Takahata, T. Kagoshima, K. Shirai, K. Tanaka, J.O. Park, H. Obata and Y. Sano, 2019. Assessment of helium isotopes near the Japan Trench 5 years after the 2011 Tohoku-Oki earthquake. ACS Earth and Space Chemistry, 3, 581 – 587.
  12. Amakawa, H, T.-L. Yu, H. Tazoe, H. Obata, T. Gamo, Y. Sano, C.-C. Shen and K. Suzuki, 2019. Neodymium concentration and isotopic composition distributions in the southwestern Indian Ocean and the Indian sector of the Southern Ocean. Chemical Geology, 511, 190 – 203.
  13. Wong, K.H, H. Obata, T. Kim, Y. Wakuta and S. Takeda, 2019. Distribution and speciation of copper and its relationship with FDOM in the East China Sea. Marine Chemistry, 212, 96 – 107.
  14. Lutfi Firdaus, M, A.S. Mashio, T. Kim, R. Muhammad, J.A. McAlister, H. Obata, T. Gamo and R. Khaydarov, 2018. Simultaneous determination of picomolar zirconium, hafnium, niobium and tantalum in seawater using commercially available chelating resin and subsequent ICP-MS determination. Geochemical Journal 52(5), 427 – 431.
  15. Takahata, N, K. Shirai, K. Ohmori, H. Obata, T. Gamo and Y. Sano, 2018. Distribution of helium-3 plumes and deep-sea circulation in the central Indian Ocean. Terrestrial, Atmospheric and Oceanic Sciences, 29(3), 331-340.
  16. Rasheduzzaman, Md., M. Kawaguchi, H. Obata and M. Maruo, 2018. Determination of dissolved and particulate thiols in Lake Biwa water and extracted fulvic acids by solid phase extraction followed by HPLC with fluorescence detection. Limnology, 19, 299 – 309.
  17. Wong, K.H, H. Obata, T. Kim, A.S. Mashio, H. Fukuda and H. Ogawa, 2018. Organic complexation of copper in estuarine waters: An assessment of the multi-detection window approach. Marine Chemistry, 204, 144 – 151.
  18. Kim, T., H. Obata, S. Takeda, K. H. Wong, A. S. Mashio and T. Gamo, 2018. Organic complexation of zinc in a coastal hydrothermal area, Tachibana Bay, Nagasaki, Japan. Geochemical Journal, 52, e29 – e38.
  19. Lutfi Firdaus, M., A. S. Mashio, H. Obata, J. A. McAlister and K. J. Orians, 2018. Distribution of zirconium, hafnium, niobium and tantalum in the North Atlantic Ocean, northeastern Indian Ocean and its adjacent seas. Deep-Sea Research-I, 140, 128-135.
  20. Schlitzer, R., and GEOTRACES group, 2018. The GEOTRACES Intermediate Data Product 2017. Chemical Geology, 493, 210–223.
  21. Kim, T., H. Obata, J. Nishioka and T. Gamo, 2017. Distribution of dissolved zinc in the western and central subarctic North Pacific. Global Biogeochemical Cycles, 10.1002/2017GB005711.
  22. Nishioka, J. and H. Obata, 2017. Dissolved iron distribution in the western and central subarctic Pacific – HNLC water formation and biogeochemical processes -. Limnology and Oceanography, 62, 2004–2022, doi: 10.1002/lno.10548.
  23. Mashio, A. S., H. Obata, and T. Gamo, 2017. Dissolved platinum concentrations in coastal seawater: Boso to Sanriku, Japan. Archives of Environmental Contamination and Toxicology, 73 (2), 240-246.
  24. Lutfi Firdaus, M., I. Fitriani, S. Wyantuti, Y. W. Hartati, Khaydarov, J. A. McAlister, H. Obata and T. Gamo, 2017. Colorimetric Detection of Mercury (II) Ion in Aqueous Solution Using Silver Nanoparticles. Analytical Sciences, 33(7), 831-837.
  25. Wakaki, S., H. Obata, H. Tazoe and T. Ishikawa, 2017. Precise and accurate analysis of deep and surface seawater Sr stable isotopic composition by double-spike thermal ionization mass spectrometry. Geochemical Journal, 51, 227-239, doi:10.2343/geochemj.2.0461.
  26. Obata, H., J. Nishioka, T. Kim, K. Norisuye, S. Takeda, Y. Wakuta and T. Gamo, 2017. Dissolved iron and zinc in Sagami Bay and the Izu-Ogasawara Trench. Journal of Oceanography, 73, 333-344. doi:10.1007/s10872-016-0407-8.
  27. Tazoe, H., H. Obata, M. Tomita, S. Mamura, J. Nishioka, T. Yamagata, Z. Karube, and M. Yamada., 2017. Novel method for low level Sr-90 activity detection in seawater by combining oxalate precipitation and chelating resin extraction. Geochemical Journal, 51, pp. 193-197, doi:10.2343/geochemj.2.0441.
  28. Kondo, Y., H. Obata, N. Hioki, A. Ooki, S. Nishino, T. Kikuchi, K. Kuma, 2016. Transport of trace metals (Mn, Fe, Ni, Zn and Cd) in the western Arctic Ocean (Chukchi Sea and Canada Basin) in late summer 2012. Deep-Sea Research-I, 116, 236-252.
  29. Mashio, A. S., H. Obata, H. Tazoe, M. Tsutsumi, A. Ferrer i Santos, and T. Gamo, 2016. Dissolved platinum in river water and seawater around Tokyo Bay and Otsuchi Bay in Japan. Estuarine, Coastal and Shelf Science, 180, 160-167.
  30. Nakayama, N., T. Tokieda, A. Suzuki, T. Kim, T. Gamo and H. Obata, 2016. Size fractionation of nanoparticulate metal sulfides in oxic waters of Lake Teganuma, Japan. Geochemical Journal, 50, doi:10.2343/geochemj.2.0408.
  31. Tazoe, H., H. Obata, T. Yamagata, Z. Karube, H. Nagai, M. Yamada, 2016. Determination of strontium-90 from direct separation of yttrium-90 by solid phase extraction using DGA Resin for seawater monitoring. Talanta, 152, 219-227.
  32. Maruo, M., M. Ishimaru, Y. Azumi, A. Fukuizumi, Y. Kawasumi, O. Nagafuchi, and H. Obata, 2016. Comparison of soluble reactive phosphorous and orthophosphate concentrations in river waters. Limnology, 17, 7-12.
  33. Lee, J.-M., E. A. Boyle, T. Gamo, H. Obata, K. Norisuye and Y. Echegoyen, 2015. Impact of anthropogenic Pb and ocean circulation on the recent distribution of Pb isotopes in the Indian Ocean. Geochimica et Cosmochimica Acta, 170, 126-144.
  34. Yamashita, Y., C.-J. Lu, H. Ogawa, J. Nishioka, H. Obata, and H. Saito, 2015. Application of in situ fluorometer for determining distribution of fluorescent organic matter in the open ocean. Marine Chemistry, 177, 298-305.
  35. The GEOTRACES Group (The GEOTRACES Group comprises a total of 135 authors, as mentioned in the appendix.), 2015. The GEOTRACES Intermediate Data Product 2014. Marine Chemistry, 177, 1–8. doi:10.1016/j.marchem.2015.04.005.
  36. Kim, T, H. Obata and T. Gamo, 2015. Dissolved zinc and its speciation in the northeastern Indian Ocean and Andaman Sea. Frontiers in Marine Science, 2:60. doi: 10.3389/fmars.2015.00060.
  37. Nakayama, N., T. Gamo, K. Shirai, Y. Sano and H. Obata, 2015. Chemical speciation and vertical profiles of dissolved sulfides in oxic seawater over the sublittorial hydrothermal area of Kikai Caldara: Dispersed hydrothermally-derived sulfides throughout the water column. Geochemical Journal, 49, pp. e1-e7, doi:10.2343/geochemj.2.0374.
  38. Kim, T., H. Obata, Y. Kondo, H. Ogawa, and T. Gamo, 2015. Distribution and speciation of dissolved zinc in the western North Pacific and its adjacent seas. Marine Chemistry, 173, 330-341.
  39. Kim, T., H. Obata, T. Gamo and J. Nishioka, 2015. Sampling and onboard analytical methods for determining subnanomolar concentrations of zinc in seawater. Limnology and Oceanography: Methods, 13, 30-39.
  40. Tazoe, H., T. Yamagata, Y. Sakuma, R. Watanabe, T. Matsumura, H. Obata and H. Nagai, 2014. Determination of picomolar beryllium levels in seawater with inductively coupled plasma mass spectrometry following silica-gel preconcentration. Analytica Chimica Acta, 852, 74-81.
  41. Suzuki, A., H. Obata, A.Okubo and T. Gamo, 2014. Precise determination of dissolved platinum in seawater of the Japan Sea, the Sea of Okhotsk and the western North Pacific. Marine Chemistry, 166, 114-121.
  42. Hioki, N., K. Kuma, Y. Morita, R. Sasayama, A. Ooki, Y. Kondo, H. Obata, J. Nishioka, Y. Yamashita, S. Nishino, T. Kikuchi, and M. Aoyama. Laterally spreading iron, humic-like dissolved organic matter and nutrients in cold, dense subsurface water of the Arctic Ocean, Scientific Reports, 4: 6775, DOI: 10.1038/srep06775.
  43. Echegoyen, Y., E. A. Boyle, J.-M. Lee, T. Gamo, H. Obata, and K. Norisuye, 2014. Recent distribution of lead in the Indian Ocean – The impact of regional emission. Proceedings of the National Academy of Sciences of the United States of America, doi/10.1073/pnas.1417370111.
  44. Kawagucci, S., T. Narita, H. Obata, H. Ogawa, and T. Gamo, 2014. Molecular hydrogen and carbon monoxide in seawater in an area adjacent to Kuroshio and Honshu Island in Japan. Marine Chemistry, 164, 75-83.
  45. Okubo, A., H. Obata, M. Magara, T. Kimura, H. Ogawa, 2013. Rapid collection of iron hydroxide for determination of Th isotopes in seawater. Analytica Chimica Acta, 804, 120-125.
  46. Amakawa, H., H. Tazoe, H. Obata, T. Gamo and Y. Sano, 2013. Neodymium isotopic composition and concentration in the central South Pacific Ocean. Geochemical Journal, 47, 409-422.
  47. Okubo, A., S. Takeda, H. Obata, 2013. Atmospheric deposition of trace metals to the western North Pacific Ocean observed at coastal station in Japan. Atmospheric Research, 129-130, 20-32.
  48. Kawagucci, S., Ueno, Y., Takai, K., Toki, T., Ito, M., Inoue, K., Makabe, A., Yoshida, N., Muramatsu, Y., Takahata, N., Sano, Y., Narita, T., Teranishi, G., Obata, H., Nakagawa, S., Nunoura, T., and Gamo, T, 2013. Geochemical origin of hydrothermal fluid methane in sediment-associated fields and its relevance to the geographical distribution of whole hydrothermal circulation, Chemical Geology, 339, 213-225.
  49. Matsumoto, T., T. Maruoka, G. Shimoda, H. Obata, H. Kagi, K. Suzuki, K. Yamamoto, T. Mitsuguchi, K. Hagino, N. Tomioka, C. Sambandam, D. Brummer, P. M. Klaus and P. Aggarwal, 2013. Tritium in Japanese precipitation following the March 2011 Fukushima Daiichi Nuclear Plant accident. Science of the Total Environment, 445-446, 365-370.
  50. Nishioka, J., H. Obata, D. Tsumune, 2013. Evidence of an extensive spread of hydrothermal dissolved iron in the Indian Ocean. Earth and Planetary Science Letters, 361, 26-33: doi:10.1016/j.epsl.2012.11.040.
  51. Okubo, A., H. Obata, T. Gamo and M. Yamada, 2012. 230Th and 232Th distributions in mid-latitudes of the North Pacific Ocean: Effect of bottom scavenging. Earth and Planetary Science Letters, 339-340, 139-150.
  52. 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, 2012. 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, 10, 234-251.
  53. 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.
  54. 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, 109-124.
  55. 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.
  56. 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, 477-487.
  57. 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, 59-73.

 

「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(a)aori.u-tokyo.ac.jp)までお知らせ下さい。