大気中メタンの<sup>14</sup>C同位体比測定のための試料調製  [in Japanese] Preparation of trace amount of atmospheric methane for measuring <sup>14</sup>C isotopic ratio  [in Japanese]

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Author(s)

    • 森泉 純 MORIIZUMI Jun
    • 名古屋大学工学部原子核工学科 Dept. of Nuclear Engineering, School of Engineering, Nagoya University
    • 永峰 康一郎 NAGAMINE Koichiro
    • 名古屋大学工学部原子核工学科|(現)名古屋大学大学院人間情報学研究科物質・生命情報学専攻 Dept. of Nuclear Engineering, School of Engineering, Nagoya University|(Present address) Division of Informatics for Natural Science, Graduate School of Human Informatics, Nagoya University

Abstract

Carbon-14 isotopic measurements of atmospheric methane (CH<sub>4</sub>) provide useful information on its sources and behavior. We have assembled a preparation line to concentrate and purify low levels (〜2 ppmv) of methane for the measurement of <sup>14</sup>C content with accelerator mass spectrometry (AMS). In this system, trace amounts of methane in nearly 1 m<sup>3</sup> of air sample are cryogenically adsorbed on active carbon, purified by gas chromatography, combusted and collected as carbon dioxide. The mean yield of this procedure is 88.6±5.8 (1σ) %. Carbon dioxide, obtained from the above procedure, is divided into two parts : one portion is converted to graphite for AMS, and the other is used for δ<sup>13</sup>C measurement. Sample contamination is negligible compared with the precision of 〜1 pM (1σ) for AMS. The effect of isotopic fractionation in this procedure is also smaller than any of the source of contamination. The overall error of this procedure is lower than 1 ‰ for the δ<sup>13</sup>C measurement. From isotopic measurements of atmospheric methane in Nagoya City at the beginning of 1994, we found a high methane concentration air sample in which <sup>14</sup>C content of methane was lower. This implies the contribution of fossil methane to the urban atmosphere.

Journal

  • Chikyukagaku

    Chikyukagaku 29(2), 99-111, 1995

    The Geochemical Society of Japan

References:  15

Cited by:  1

Codes

  • NII Article ID (NAID)
    110008679904
  • NII NACSIS-CAT ID (NCID)
    AN00141280
  • Text Lang
    JPN
  • Article Type
    Journal Article
  • ISSN
    0386-4073
  • NDL Article ID
    3916119
  • NDL Source Classification
    ZM41(科学技術--地球科学)
  • NDL Call No.
    Z15-645
  • Data Source
    CJP  CJPref  NDL  NII-ELS  J-STAGE 
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