| Project/Area Number |
09554030
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
地球化学
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| Research Institution | TOKYO METROPOLITAN UNIVERSITY |
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Principal Investigator |
NARAOKA Hiroshi Dept. of Chemistry, Tokyo Metropolitan Univ., Assoc. Prof., 理学研究科, 助教授 (20198386)
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| Co-Investigator(Kenkyū-buntansha) |
KOMIYA Masatoshi Resource & Energy Dept., Geological Survey of Japan, Senior Researcher, 燃料資源部, 主任研究官
ISHIWATARI Ryoshi Dept. of Chemistry, Tokyo Metropolitan Univ., Prof., 理学研究科, 教授 (90087106)
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| Project Period (FY) |
1997 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥9,500,000 (Direct Cost: ¥9,500,000)
Fiscal Year 1999: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 1998: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1997: ¥7,000,000 (Direct Cost: ¥7,000,000)
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| Keywords | low-molecular wieght organic acids / carbon isotope ratios / monocarboxylic acids / dicarboxylic acids / oil field water / pyrolysis / GC / C / IRMS / 降水 / ケロジェン / クラッキングモデル / 速度論的同位体効果 / 同位体平衡 / ヒドロキシカルボン酸 / 分子レベル炭素同位体比 / 固相マイクロ抽出 |
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| Research Abstract |
Carbon isotopic compositions of individual low-molecular carboxylic acids such as acetic acid and oxalic acid were measured on sub-nano mol level using gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). While free monocarboxylic acids are hard to oxidaze to COィイD22ィエD2 quantatively in a micro volume furnace, decyl ester derivatives of the acids are easier to convert to COィイD22ィエD2. Also the dicarboxylic acids were derivatized to dibutyl esters for the GC/C/IRMS measurement. Using internal isotopic standards of n-alkanes, analytical precision was within ±0.3‰. Isotopic mass balance calculation shows that the corrected analytical precisions are 2-3‰ for the free acids.
Carbon isotopic compositions of individual organic acids in oil-field waters from Sarukawa Oil Field (Funakawa Formation, Miocene) in the northern Japan. The δィイD113ィエD1C values of acetic acid and propanoic acid range widely from -61 to -23‰ (relative to PDB) and -from -51 to -28‰, respectively. The low-molecular acids are more depleted in ィイD113ィエD1C than the bulk crude oil (ca. -22‰) produced from the same formation. The δィイD113ィエD1C values of acetic acid correlate well (rィイD12ィエD1=0.94) with those of propanoic acid (n=7 with one exception). Isotopically heavy acids tend to be observed in higher temperature water. In addition we conducted hydrous pyrolysis of kerogen purified from the same formation. The isotopic composition of acetic acid and propanoic acid produced by the pyrolysis experiment is plotted on the correlation that is observed in natural samples. These results suggest that the low-molecular monocarboxylic acids are produced by cracking of kerogen.
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