Mechanism for precipitation of ikaite crystals in sea ice

2016 Fiscal Year Annual Research Report

• Project/Area Number: 15K16135
• Research Institution: Hokkaido University
• Principal Investigator: 野村 大樹 北海道大学, 水産科学研究院, 助教 (70550739)
• Project Period (FY): 2015-04-01 – 2017-03-31
• Keywords: 海氷 / 炭酸カルシウム / 炭素循環 / 極域海洋

Outline of Annual Research Achievements

イカイトは、炭酸カルシウムの6 水和塩の結晶であり、近年、遂に南極海の海氷内から発見された。しかし、海氷内でイカイトがどのような条件で、どれだけ生成するか等のメカニズムについては全く分かっていない。本研究では、海氷内に存在するイカイトの析出メカニズムを明らかにすることを目的とし、室内海氷生成実験および野外海氷現場観測を実施した。

1. 室内海氷生成実験：北海道大学低温実験施設を利用し、海氷生成タンクで人工海氷を作成した。結氷温度および時間、海水の化学成分（pH）を調整し、様々な条件で実験を実施した。結氷温度が低いほど、海氷内部の温度が低下し、海氷内ブラインにおける化学成分が濃縮することによって、イカイト結晶の数は多くなった。また、結氷時間が長いほど、イカイト結晶が成長するためサイズは大きくなった。そして、海水のpHを高くした際、通常の海水に対してイカイト結晶の数は多くなった。以上の結果より、条件（結氷温度、時間、海水の化学成分）によって、イカイトの析出条件を詳細に記述することが出来た。

2. 野外海氷現場観測：ノルウェー極地研究所が所有する砕氷船『Lance』を用いた北極海での長期海氷観測航海（平成27 年1-6 月）および海上保安庁が所有する砕氷巡視船『そうや』を用いたオホーツク海での海氷観測航海においてイカイトサンプル採取を試みた。航海中、海氷を約100サンプル採取し、イカイト結晶の有無を確認した。しかし、すべてのサンプルにおいてイカイト結晶は発見されなかった。近年極域では、海氷上の積雪が顕著であり、雪の断熱効果によって、海氷温度が-6度以上と高いために、イカイト析出に至らなかったと考えた。また、近年の海洋酸性化によるpHの低下などもイカイト結晶の析出を抑制したために、イカイト析出に至らなかったと考えた。

Research Products

• [Int'l Joint Research] ノルウェー極地研究所/ノルウェー海洋研究所(ノルウェー)
  • Country Name: NORWAY
  • Counterpart Institution: ノルウェー極地研究所/ノルウェー海洋研究所
• [Int'l Joint Research] ブリュッセル自由大学/リエージュ大学(ベルギー)
  • Country Name: BELGIUM
  • Counterpart Institution: ブリュッセル自由大学/リエージュ大学
• [Int'l Joint Research] タスマニア大学/オーストラリア南極局(オーストラリア)
  • Country Name: AUSTRALIA
  • Counterpart Institution: タスマニア大学/オーストラリア南極局
• [Int'l Joint Research] アルフレッドウェゲナー極地海洋研究所(ドイツ)
  • Country Name: GERMANY
  • Counterpart Institution: アルフレッドウェゲナー極地海洋研究所
• [Journal Article] Macro-nutrient concentrations in Antarctic pack ice: Overall patterns and overlooked processes. (2017)
  • Author(s): Fripiat F, Meiners K.M, Vancoppenolle M, Ackley S.F, Arrigo K, Carnat G, Cozzi S, Delille B, Dieckmann G.S, Dunbar R.B, Fransson A, Kattner G, Kennedy H, Lannuzel D, Munro D.R, Nomura D, Papadimitriou S, Rintala J.M, Schoemann V, Stefels J, Steiner N, Thomas D.N, Tison J-L.
  • Journal Title: Elementa-Science of the Anthropocene Volume: 5, 13 Pages: -
  • DOI: DOI: https://doi.org/10.1525/elementa.217
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] On the extraordinary snow on the sea ice off East Antarctica in late winter, 2012 (2016)
  • Author(s): Toyota T, Massom R, Lecomte O, Nomura D, Heil P, Tamura T, Fraser A.D.
  • Journal Title: Deep-Sea Research Part II Volume: 131 Pages: 53-67
  • DOI: doi:10.1016/j.dsr2.2016.02.003
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Effect of elevated CO2 concentration on the microalgae in Antarctic pack ice algal communities. (2016)
  • Author(s): Coad T, McMinn A, Nomura D, Martin A
  • Journal Title: Deep-Sea Research Part II Volume: 131 Pages: 60-69
  • DOI: doi:10.1016/j.dsr2.2016.01.005
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] DMSP and DMS cycling within Antarctic sea ice during the winter spring transition (2016)
  • Author(s): Damm E, Nomura D, Dieckmann G.S, Martin A, Meiners K.M.
  • Journal Title: Deep-Sea Research Part II Volume: 131 Pages: 150-159
  • DOI: doi:10.1016/j.dsr2.2015.12.015
  • Peer Reviewed / Int'l Joint Research
• [Presentation] Macronutrients in Sea Ice: Overall Patterns and Related Processes (2017)
  • Author(s): Fripiat F, Meiners K.M, Vancoppenolle M, Ackley S.F, Arrigo K, Carnat G, Cozzi S, Delille B, Dieckmann G.S, Dunbar R.B, Fransson A, Kattner G, Kennedy H, Lannuzel D, Munro D.R, Nomura D, Papadimitriou S, Rintala J.M, Schoemann V, Stefels J, Steiner N, Thomas D.N, Tison J-L.
  • Organizer: Gordon Research Conference, Polar Marine Science
  • Place of Presentation: Ventura Beach Marriott in Ventura, CA, United States
  • Year and Date: 2017-03-26 – 2017-03-31
  • Int'l Joint Research / Invited
• [Presentation] Influence of sea-ice crack formation on the spatial distribution of nutrients and microalgae in flooded Antarctic multi-year sea ice. (2017)
  • Author(s): Nomura D., S. Aoki, D. Simizu, T. Iida.
  • Organizer: Gordon Research Conference, Polar Marine Science
  • Place of Presentation: Ventura Beach Marriott in Ventura, CA, United States
  • Year and Date: 2017-03-26 – 2017-03-31
  • Int'l Joint Research
• [Presentation] Snow contribution to the air-sea ice gas exchange process (2017)
  • Author(s): Nomura D.
  • Organizer: J-ARC Net meeting
  • Place of Presentation: 北海道大学創成研究機構（北海道札幌市）
  • Year and Date: 2017-03-15 – 2017-03-15
• [Presentation] リュツォホルム湾広域における海水および海氷コア採取の必要性と今後の展開 (2017)
  • Author(s): 野村大樹, 牛尾収輝, 豊田威信, 田村岳史, 清水大輔, 平野大輔, 小野数也, 橋田元, 青木茂
  • Organizer: ROBOTICA研究集会
  • Place of Presentation: 国立極地研究所（東京都立川市）
  • Year and Date: 2017-01-14 – 2017-01-14
• [Presentation] Quasi-periodic breakup of multi-year landfast ice in Lutzow-Holm Bay, Antarctica: Physical processes and some possible factors of breakup events (2016)
  • Author(s): Ushio S., T. Toyota, D. Nomura, K. Naoki
  • Organizer: The Seventh Symposium on Polar Science
  • Place of Presentation: National Institute of Polar Research, Tachikawa, Tokyo, Japan
  • Year and Date: 2016-11-29 – 2016-12-02
  • Int'l Joint Research
• [Presentation] Growth and decay processes deduced from the fast-ice cores collected near the Syowa Station (2016)
  • Author(s): Toyota T., S. Ushio, T. Tamura, D. Nomura, K. Naoki, A. Fraser
  • Organizer: The Seventh Symposium on Polar Science
  • Place of Presentation: National Institute of Polar Research, Tachikawa, Tokyo, Japan
  • Year and Date: 2016-11-29 – 2016-12-02
  • Int'l Joint Research
• [Presentation] Incorporation and degradation processes of biogeochemical compounds within Antarctic multi-year land-fast sea ic (2016)
  • Author(s): Nomura D., S. Aoki, D. Simizu, T. Toyota, S. Ushio, K. Naoki, T. Tamura
  • Organizer: The Seventh Symposium on Polar Science
  • Place of Presentation: National Institute of Polar Research, Tachikawa, Tokyo, Japan
  • Year and Date: 2016-11-29 – 2016-12-02
  • Int'l Joint Research
• [Presentation] Interpretation of both-polar environmental variability through the investigation of sea ice variability (2016)
  • Author(s): Tamura T., K. Mizobata, E. Watanabe, M. Sampei, M. Yamamoto, D. Nomura, J. Nishioka, Y. Watanabe
  • Organizer: The Seventh Symposium on Polar Science
  • Place of Presentation: National Institute of Polar Research, Tachikawa, Tokyo, Japan
  • Year and Date: 2016-11-29 – 2016-12-02
  • Int'l Joint Research
• [Presentation] CO2 fluxes from younger and thinner Arctic sea ice (2016)
  • Author(s): Nomura D., M. A. Granskog, B. Delille, A. Fransson, A. Silyakova, L. Cohen, M. Chierici, G. S. Dieckmann, S. R. Hudson, K. I. Ohshima
  • Organizer: The Seventh Symposium on Polar Science
  • Place of Presentation: National Institute of Polar Research, Tachikawa, Tokyo, Japan
  • Year and Date: 2016-11-29 – 2016-12-02
  • Int'l Joint Research
• [Presentation] 室内実験による海氷表面でのブロモホルム生成機構の解明 (2016)
  • Author(s): 野村大樹, 大木淳之, P. Assmy, 今井良輔
  • Organizer: 日本海洋学会秋季大会
  • Place of Presentation: 鹿児島大学（鹿児島県鹿児島市）
  • Year and Date: 2016-09-14 – 2016-09-14
• [Presentation] Observations of Arctic sea ice and ocean biogeochemistry in the new thinner ice era: the N-ICE2015 drift ice expedition (2016)
  • Author(s): Granskog M.A., P. Assmy, P. Duarte, M. Ferndez-Mndez, A. Fransson, H. Kauko, L.M. Olsen, M. Chierici, D. Nomura, C. J. Munday H. Steen
  • Organizer: Goldschmidt2016
  • Place of Presentation: Pacifico Yokohama, Yokohama-shi, Kanagawa, Japan
  • Year and Date: 2016-06-26 – 2016-07-01
  • Int'l Joint Research
• [Presentation] Role of sea-ice crack formation on biological productivity and transport of biogeochemical components into sea ice (2016)
  • Author(s): Nomura D., S. Aoki, D. Simizu.
  • Organizer: Goldschmidt2016
  • Place of Presentation: Pacifico Yokohama, Yokohama-shi, Kanagawa, Japan
  • Year and Date: 2016-06-26 – 2016-07-01
  • Int'l Joint Research
• [Presentation] Wintertime sea-ice chemistry and influence of glacial freshwater discharge during two contrasting years in a Spitsbergen fjord. (2016)
  • Author(s): Fransson A., M. Chierici, D. Nomura, M. A. Granskog, S. Kristiansen, T. Martma, G. Nehke
  • Organizer: Goldschmidt2016
  • Place of Presentation: Pacifico Yokohama, Yokohama-shi, Kanagawa, Japan
  • Year and Date: 2016-06-26 – 2016-07-01
  • Int'l Joint Research
• [Presentation] Sea-ice biogeochemistry in the Arctic Ocean (2016)
  • Author(s): Nomura D.
  • Organizer: Japan－Norway Arctic Science and Innovation Week 2016
  • Place of Presentation: Tokyo International Exchange Center, Minato-ku, Tokyo, Japan
  • Year and Date: 2016-06-02 – 2016-06-03
  • Int'l Joint Research
• [Presentation] 海氷変動を軸とした両極の環境変動の解明 (2016)
  • Author(s): 田村岳史, 溝端浩平, 渡邉英嗣, 三瓶真, 山本正伸, 野村大樹, 西岡純, 渡邉豊
  • Organizer: 日本地球惑星連合大会
  • Place of Presentation: 幕張メッセ（千葉県千葉市）
  • Year and Date: 2016-05-22 – 2016-05-26
• [Presentation] 南大洋インド洋区季節海氷域における溶存炭酸物質の空間分布と時間変化 (2016)
  • Author(s): 橋田元, 高村友海, 野村大樹, 吉川久幸
  • Organizer: 日本地球惑星連合大会
  • Place of Presentation: 幕張メッセ（千葉県千葉市）
  • Year and Date: 2016-05-22 – 2016-05-26
• [Presentation] Winter-to-spring evolution of Arctic Ocean acidification state in under-ice water and effect of sea-ice dynamics during N-ICE2015 ice drift project (2016)
  • Author(s): Fransson A., M. Chierici, P. Assmy, P. Dodd, A. Meyer, M. A. Granskog, D. Nomura, A. Rusel, M. Fernndez-Mndez, A. Silyakova, H. Steen
  • Organizer: 4th International Symposium on the Ocean in a High-CO2 World
  • Place of Presentation: Hotel Grand Chancellor, Hobart, Tasmania, Australia
  • Year and Date: 2016-05-03 – 2016-05-06
  • Int'l Joint Research
• [Presentation] Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC). (2016)
  • Author(s): Dethloff K., M. Rex, M. Shupe, A. Sommerfeld, ......D. Nomura, I. Peeken, J. Pelon, D. Perovich, O. Persson, C. Provost, B. M. Wendisch, H. Yang, X. Zhang.
  • Organizer: European Geosciences Union General Assembly 2016, 20 April
  • Place of Presentation: Austria Center Vienna, Vienna, Austria
  • Year and Date: 2016-04-17 – 2016-04-22
  • Int'l Joint Research
• [Remarks] Daiki Nomura sea ice biogeochemistry
  • URL: https://dnomura.jimdo.com/
• [Remarks] Hokusui-ocean-biogeochemistry
  • URL: https://hokusui-ocean-biogeochemistry.jimdo.com/