Researches in Organic Geochemistry
Online ISSN : 2189-7891
Print ISSN : 1344-9915
ISSN-L : 1344-9915
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Volume 28
Displaying 1-6 of 6 articles from this issue
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Review
  • Studies on atmospheric circulation and paleoenvironmental changes using the stable isotopes of terrestrial biomarkers
    Shinya Yamamoto
    Article type: Article
    2012 Volume 28 Pages 1-12
    Published: December 28, 2012
    Released on J-STAGE: April 18, 2017
    DOIhttps://doi.org/10.20612/rog.28.0_1
    JOURNAL FREE ACCESS
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    Long-chain n-alkyl compounds, major components of plant leaf waxes, have been recognized as important terrestrial biomarkers. This is because molecular and stable carbon (δ13C) and hydrogen (δD)isotopic compositions of these compounds have a significant potential to reconstruct past changes in the plant growing environment and compositional changes in the source vegetation. However, delivery mechanism of terrestrial biomarkers in the atmosphere still remains unclear. This paper reviews recent studies on the δ13C and δD analyses of long-chain n-alkyl compounds in marine and bog sediments, and discusses their advantages and disadvantages for paleoenvironmental studies. In addition, this paper also reviews studies on the atmospheric transport process of these biomarkers to the Northwest Pacific based on their δ13C and δD measurements in the atmospheric aerosols from the Asian continent. The results of these studies suggest that further elucidation of the transport process of terrestrial biomarkers is necessary to increase their palaeoclimatic utility in sedimentary records, especially in which the biomarkers are long-range atmospheric transported from the continent.
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Article
  • Stable nitrogen isotopic fractionation associated with transamination of glutamic acid to aspartic acid : implications for understanding 15N trophic enrichment in ecological food webs
    Kasumi Miura, Akiko S. Goto
    Article type: Article
    2012 Volume 28 Pages 13-17
    Published: December 28, 2012
    Released on J-STAGE: April 18, 2017
    DOIhttps://doi.org/10.20612/rog.28.0_13
    JOURNAL FREE ACCESS
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    The stable nitrogen isotope ratio of glutamic acid is increased by 〜8.0‰ during trophic level changes in ecological food webs. It has been hypothesized that significant isotopic fractionation occurs associated with glutamic acid metabolism during transamination or deamination in heterotrophic animals. However, few studies have investigated the isotopic fractionation factor (α) in this process, even though knowledge of this factor is critical in quantitatively evaluating the flux of amino acid metabolism in animals. In this study we determined the value of a associated with an enzymatic transamination of glutamic acid to aspartic acid in vitro. We found 0.1‰ and 2.2‰ enrichment of 15N following the enzymatic transamination of glutamic acid for 10 and 60min, respectively. Using a Rayleigh model, the α value in this reaction was estimated to be 0.9958. Although this value is associated with much uncertainty (0.9949-0.9968) when applying it to test for an 8.0‰ enrichment, 8‰ of 15N-enrichment for a α value of 0.9958 corresponds to 86% of the glutamic acid being reacted during transamination.
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Short article
  • The first experimental demonstration of thermal transformation of bacteriochlorophylls into benzoporphyrins in sediments
    Kenta Asahina, Shinya Nomoto
    Article type: Article
    2012 Volume 28 Pages 19-22
    Published: December 28, 2012
    Released on J-STAGE: April 18, 2017
    DOIhttps://doi.org/10.20612/rog.28.0_19
    JOURNAL FREE ACCESS
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    Benzoporphyrins have been found as minor components of sedimentary porphyrins. It was proposed that benzoporphyrins were derived from bacteriochlorophylls c and d, which possess 3-methyl-4-n-propyl-, or 3-methyl-4-iso-butylpyrrole units. We established the diagenetic formation process of benzoporphyrins from these bacteriochlorophylls by heating experiments of model porphyrins (2,7,12,17-tetramethyl-3,8,13,18-tetra-n-propylporphyrin and 3,8,13,18-tetra-isobutyl-2, 7, 12, 17-tetramethylporphyrin). The heating products were oxidized by chromic acid to give phthalimides, in which the profile of phthalimides clearly indicates the formation of benzopyrrole units during heating experiments. These results imply that bacteriochlorophylls c and d are potential sources of benzoporphyrins found in petroleum and sedimentary rocks.
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  • Does the symbiotic scale-worm feed on the host mussel in deep-sea vent fields?
    Yoshimi Takahashi, Yoko Sasaki, Yoshito Chikaraishi, Masashi Tsuchiya, ...
    Article type: Article
    2012 Volume 28 Pages 23-26
    Published: December 28, 2012
    Released on J-STAGE: April 18, 2017
    DOIhttps://doi.org/10.20612/rog.28.0_23
    JOURNAL FREE ACCESS
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    The scale-worm Branchipolynoe pettiboneae is frequently found in the mantle cavity of Bathymodiolus mussels living in hydrothermal vents and seeps around Japan. To investigate its feeding habits and symbiotic relationship with the host mussels, we determined the stable nitrogen isotopic composition of glutamic acid and phenylalanine for representative scale-worms including a symbiotic juvenile and a symbiotic adult, both with their host mussels, and a free-living adult, collected from hydrothermal vents of the Hatoma Knoll (〜1532 m in depth) in the Okinawa Trough, Japan. The isotopic data suggested the feeding habits that Bathymodiolus platifrons is a major source of amino acids for symbiotic adult scale-worm but not for free-living adult and symbiotic juvenile scale-worms.
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  • Methyl and ethyl chloroformate derivatizations for compound-specific stable isotope analysis of fatty acids-II
    Kanji Aoyagi, Atsuko Yamanaka, Akiko S. Goto, Tatsuya Fujino, Takashi ...
    Article type: Article
    2012 Volume 28 Pages 27-30
    Published: December 28, 2012
    Released on J-STAGE: April 18, 2017
    DOIhttps://doi.org/10.20612/rog.28.0_27
    JOURNAL FREE ACCESS
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    Methyl (MCF) and ethyl chloroformate (ECF) derivatizations are potentially useful for rapid and simple esterification (i.e., at room temperature for 5 min) prior to compound-specific stable isotope analysis (CSIA) of fatty acids. In this study, we have used acetonitrile as an organic solvent in the esterification process to improve the yields of derivatives, and we evaluated whether the improved esterification is suitable for carbon and hydrogen CSIA. Six saturated (14:0, 16:0, 18:0, 20:0, 22:0, and 24:0) and three unsaturated (18:1 n-9, 18:2 n-6, and 18:3 n-3) fatty acids were used in this study. The yields of derivatives are 67-107% for MCF and 84-89% for ECF derivatizations, which are approximately twice the yields obtained in MCF and ECF derivatizations that did not use acetonitrile. The accuracy of the CSIA is <±0.4‰ (1σ) for carbon and <± 11‰ (1σ) for hydrogen, with no significant differences in these uncertainties observed for saturated and unsaturated fatty acids. Thus, MCF and ECF derivatizations using acetonitrile are suitable for the CSIA of fatty acids.
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Technical paper
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