Japan Geoscience Union Meeting 2014

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Poster

Symbol M (Multidisciplinary and Interdisciplinary) » M-TT Technology & Techniques

[M-TT42_2PO1] Frontiers in Geochemistry : Innovative approaches for Earth and Planetary Sciences

Fri. May 2, 2014 4:15 PM - 5:30 PM Poster (3F)

Convener:*Yokoyama Yusuke(Atmosphere and Ocean Research Institute, University of Tokyo), Hiroyuki Kagi(Geochemical Laboratory, Graduate School of Science, University of Tokyo), Shogo Tachibana Shogo(Department of Natural History Scieces, Hokkaido University), Takafumi Hirata(Graduate School of Science, Kyoto University), Urumu Tsunogai(Graduate School of Environmental Studies, Nagoya University), Katsuhiko Suzuki(Institute for Research on Earth Evolution, Japan Agency for Marine-Earth Science and Technology), Gen Shimoda(Geological Survey of Japan, AIST), Hirochika Sumino(Geochemical Research Center, Graduate School of Science, University of Tokyo), Hajime Obata(Marine inorganic chemistry division, Atmosphere and Ocean Research Institute, University of Tokyo), Yoshio Takahashi(Department of Earth and Planetary Systems Science, Graduate School of Science, Hiroshima University), Tetsuya Yokoyama(Department of Earth and Planetary Sciences, Graduate School of Science and Engineering, Tokyo Institute of Technology)

4:15 PM - 5:30 PM

[MTT42-P04] Development of the technique for determination of I-129 in fish samples as new tracer of marine ecosystem

*Haruka KUSUNO1, Hiroyuki MATSUZAKI1, Toshi NAGATA2, Yosuke MIYAIRI2, Yusuke YOKOYAMA2, Naohiko OHKOUCHI3, Hironori TOKUYAMA1 (1.School of Engineering, The University of Tokyo, 2.Atmosphere and Ocean Research Institute, The University of Tokyo, 3.Japan Agency for Marine-Earth Science and Technology)

Keywords:Iodine-129, tracer, marine ecosystem, fish, AMS

The availability of 129I as a new tracer for marine ecosystem was examined.The iodine isotopic ratio (129I/127I) in seawater is determined by the anthropogenic 129I transferred from the atmosphere, i.e., it shows very high ratio as the order of 10-10 for 129I/127I at the surface or surface mixing layer and suddenly decreases going deeper to some of 10-12 or lower. Iodine isotopic ratio (129I/127I) of marine lives like fish should be determined by their habitats and the ways exchanging iodine with seawater. This means that the iodine isotopic ratio is potential indicator of marine ecosystem. However there have been only few studies using 129I for marine ecosystem. This is because 129I is so trace in the marine lives that ordinary analytical techniques cannot detect.Recent development of analytical technique for 129I using AMS (Accelerator Mass Spectrometry) enables determine trace amount of 129I concentration in environmental samples.In this study the pyrohydrolysis method was applied to extract iodine from fish samples. A freeze-dried and homogenized fish sample, 0.1g to 0.5g, was combusted in the quartz tube under oxygen and water vapor flow. Iodine was extracted into an alkaline solution. An aliquot of this solution was taken for ICP-MS analysis to determine the stable iodine (127I) concentration. The remaining was, added with carrier iodine (about 1 mg), purified by solvent extraction and collected as AgI precipitation. 129I/127I ratio was determined by AMS. From the AMS result and the 127I concentration, the 129I/127I ratio of the fish samples themselves can be calculated.The extraction yield was evaluated using IAEA-414 fish standard sample. Background in the pyrohydrolysis was also examined.The preliminary results of fish samples, collected from Suruga-bay (located on Pacific coast in the middle of Honshu, Japan) showed 1×10-10 to 7×10-10, which was consistent with that of surface seawater.