PAGES Japan

Takeshi NAKATSUKA
Associate Professor
Institute of Low Temperature Science
Hokkaido University
Office: North 19, West 8, Kita-Ku
Sapporo 060-0819
Japan

Phone: +81-11-706-5504
Fax: +81-11-706-7142
Email: nakatuka@lowtem.hokudai.ac.jp
Website: http://environ.lowtem.hokudai.ac.jp/nakatsuka/nakatsuka_top-e.htm

Research fields

Marine Biogeochemistry, Isotopic Geochemistry, Paleoceanography, Paleoclimatology

Current research

My current research interests are variability of "water cycle" and "water-associated material cycle" in the present and past, and their impacts on ecosystems and human societies. They cover both of the terrestrial and marine environments and the modern and past researches, including topics such as "Linkage between inland and open-ocean ecosystems (industries) by material transports through large river and ocean currents" and "Teleconnection between East Asian summer monsoon and ENSO". My major research targets are deep-sea sediment cores and tree-ring disks together with modern water, air and biological samples, which are analyzed mainly by isotopic and/or organic geochemical methods. My major research fields are the whole of Japanese archipelago and surrounding seas, with special focus on the Sea of Okhotsk and its catchment area "Amur River Basin" in Russian Far East.

Recent publications related to PAGES

• Nakatsuka, T., C. Yoshikawa, M. Toda, K. Kawamura and M. Wakatsuchi (2002): An extremely turbid intermediate water in the Sea of Okhotsk : Implication for the transport of particulate organic carbon in a seasonally ice-bound sea. Geophysical Research Letter, 29, 10.1029/2001GL014029.
• Narita, H., M. Sato, S. Tsunogai, M. Murayama, M. Ikehara, T. Nakatsuka, and M. Wakatsuchi (2002): Biogenic opal indicating less productive northwestern North Pacific during the glacial ages. Geophysical Research Letter, 29, 10.1029/2001GL014320.
• Seki, O., K. Kawamura, T. Nakatsuka, K. Ohnishi M. Ikehara and M. Wakatsuchi (2003): Sediment core profiles of long-chain n-alkanes in the Sea of Okhotsk: Enhanced transport of terrestrial materials in the last deglacial to the early Holocene. Geophysical Research Letter, 30, 10.1029/2001GL014464.
• Nakatsuka, T., T. Masuzawa, J. Kanda, H. Kitazato, Y. Shirayama, M. Shimanaga and A. Yamaoka (2003): Particle dynamics in the deep water column of Sagami Bay, Japan -I: Origins of apparent flux of sinking particles. Progress in Oceanography, 57, 31-45.
• Nakatsuka, T., J. Kanda and H. Kitazato (2003): Particle dynamics in the deep water column of Sagami Bay, Japan -II: Seasonal change in profiles of suspended phytodetritus. Progress in Oceanography, 57, 47-57.
• Okazaki, Y., K. Takahashi, T. Nakatsuka and M. C. Honda (2003): The production scheme of Cycladophora davisiana (Radiolaria) in the Okhotsk Sea and the northwestern North Pacific: implication for the paleoceanographic conditions during the glacials in the high latitude oceans. Geophysical Research Letter, 30, 1939 doi.10,1029/2003 GL018070.
• Okazaki, Y., Takahashi, K., Yoshitani, H., Nakatsuka, T., Ikehara, M., and Wakatsuchi, M. (2003): Radiolarians under the seasonally sea-ice covered conditions in the Okhotsk Sea: flux and their implications for paleoceanography. Marine Micropaleontology, 49, 195-230.
• Nakatsuka, T., K. Ohnishi, T. Hara, A. Sumida, D. Mitsuishi, N. Kurita and S. Uemura (2004): Oxygen and carbon isotopic ratios of tree-ring cellulose in a conifer-hardwood mixed forest in northern Japan. Geochemical Journal, 38, 77-88.
• Seki, O., K. Kawamura, M. Ikehara, T. Nakatsuka and T. Oba (2004): Variation of alkenone sea surface temperature in the Sea of Okhotsk over the last 85 kyrs. Organic Geochemistry, 35, 347-354.
• Seki, O., M. Ikehara, K. Kawamura, T. Nakatsuka, K. Ohnishi, M. Wakatsuchi, H. Narita and T. Sakamoto (2004): Reconstruction of paleoproductivity in the Sea of Okhotsk over the last 30 kyrs. Paleoceanography, 19, PA1016, doi:10.1029/2002PA000808.
• Nakatsuka, T., T. Fujimune, C. Yoshikawa, S. Noriki, K. Kawamura, Y. Fukamachi, G. Mizuta and M. Wakatsuchi (2004): Biogenic and lithogenic particle flux in the western region of the Sea of Okhotsk: Implications for lateral material transport and biological productivity. Journal of Geophysical Research, 109, C09S13, doi:10.1029/2003JC001908.
• Nakatsuka, T., M. Toda, K. Kawamura and M. Wakatsuchi (2004): Dissolved and particulate organic carbon in the Sea of Okhotsk: Transport from continental shelf to ocean interior. Journal of Geophysical Research, 109, C09S14, doi:10.1029/2003JC001909.
• Seki, O., K. Kawamura, T. Sakamoto, M. Ikehara, T. Nakatsuka, and M. Wakatsuchi (2005): Decreased surface salinity in the Sea of Okhotsk during the last glacial period estimated from alkenones, Geophysical Research Letter, 32, L08710, doi:10.1029/2004GL022177.
• Yoshikawa, C., T. Nakatsuka and H. Kawahata (2005): Transition of low-salinity water in the Western Pacific Warm Pool recorded in the nitrogen isotopic ratios of settling particles. Geophysical Research Letter, 32, L14615, doi:10.1029/2005GL023103.
• Sakamoto, T., M. Ikehara, K. Aoki, K. Iijima, N. Kimura, T. Nakatsuka and M. Wakatsuchi (2005) : Ice-rafted debris (IRD) based sea-ice expansion events during the past 100 kyrs in the Okhotsk Sea. Deep-Sea Research II, 52, 2275-2301.
• Tsuji, H., T. Nakatsuka and K. Takagi (2006): ?18O of tree-rings cellulose in two species (spruce and oak) as proxies of precipitation amount and relative humidity in Northern Japan. Chemical Geology, 231, 67-76.
• Okazaki, Y., O. Seki, T. Nakatsuka, T. Sakamoto, M. Ikehara and K. Takahashi (2006): Cycladophora davisiana (Radiolaria) in the Okhotsk Sea : a key for reconstructing glacial ocean conditions. Journal of Oceanography, 62, 639-648.
• Nishioka, J., T. Ono, H. Saito, T. Nakatsuka, S. Takeda, T. Yoshimura, K. Suzuki, K. Kuma, S. Nakabayashi, D. Tsumune, H. Mitsudera, W. K. Johnson, and A. Tsuda (2007): Iron supply to the western subarctic Pacific: Importance of iron export from the Sea of Okhotsk. Journal of Geophysical Research, 112, C10012, doi:10.1029/2006JC004055.
• Tsuji, H., T. Nakatsuka, K. Yamazaki and K. Takagi (2007): Summer relative humidity in northern Japan inferred from tree-ring ?18O (1776-2002 AD)- Influence of paleoclimate indices of atmospheric circulation. Journal of Geophysical Research (in press).