Researches in Organic Geochemistry
Online ISSN : 2189-7891
Print ISSN : 1344-9915
ISSN-L : 1344-9915
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Volume 21
Displaying 1-6 of 6 articles from this issue
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Review
Article
  • Quantitative and qualitative characteristics of chromophoric dissolved organic matter in Pacific subarctic and subtropical surface waters
    Youhei Yamashita, Eiichiro Tanoue
    Article type: Article
    2006 Volume 21 Pages 13-22
    Published: December 26, 2006
    Released on J-STAGE: April 07, 2017
    DOIhttps://doi.org/10.20612/rog.21.0_13
    JOURNAL FREE ACCESS
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    Vertical profiles of chromophoric dissolved organic matter (CDOM) were determined by absorption coefficient and fluorescence intensity in surface waters (〜300m) at 4 stations of the western North Pacific. Vertical characteristics of CDOM were similar irrespective of differences in oceanic regions, on the one hand, i.e., levels were lower and higher in and below the temporal mixed layer, respectively. CDOM levels, on the other hand, were higher in the subarctic than in the subtropical region throughout the water columns. The ratios of fluorescence intensity to absorption coefficient increased with depth, while, the ratios were within a relatively narrow range in water layers at 4 stations, i.e., the temporal mixed layer (4.11±0.53), beneath the temporal mixed layer to 200m (6.06±1.73) and below (8.33±0.94), irrespective of differences of oceanic regions, indicating that the photochemical characteristics of CDOM in the respective water layers were similar irrespective of differences in oceanic regions. Such distributional characteristics suggested that an integrated effect of the in situ production, and photo- and bio-reactivity of CDOM in the upper water columns might give rise to a different quantity but a similar quality of CDOM among the various oceanic regimes.
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  • Early diagenetic processes of diterpenoids in Pinus densiflora: Differences of diterpenoids between forest soils and the Pond Shibu-ike sediments in Matsumoto City, Nagano Prefecture, Japan
    Yasuhiro Nozue, Kazuo Fukushima
    Article type: Article
    2006 Volume 21 Pages 23-33
    Published: December 26, 2006
    Released on J-STAGE: April 07, 2017
    DOIhttps://doi.org/10.20612/rog.21.0_23
    JOURNAL FREE ACCESS
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    Conifer plant Pinus densiflora predominates in the catchment of the Pond Shibu-ike in Matsumoto City, Nagano Prefecture, Japan. P. densiflora can supply leaf resins to the sediments in the pond. In this study, we analyzed lipids in P. densiflora leaves, forest soils, and Pond Shibu-ike sediments to understand early diagenetic processes of the abietane-type diterpenoids. P. densiflora leaves contained abietane-type precursors such as dehydroabietic acid, which might be altered to several diterpenoids in forest soils and lacustrine sediments. A great amount of compounds, of which molecular weight was 258 or 272, were detected in the litter layer of forest soil. They might be mixtures of intermediates of diterpenoid hydrocarbons derived from P. densiflora. They disappeared completely in the humic layer underlying forest soils presumably due to microbial degradation. On the other hand, aromatic and dehydro-type abietanes were identified in the Pond Shibu-ike sediment, and must be produced by early diagenetic processes from dehydroabietic acid, which was confirmed to be present in P. densiflora leaves samples. It is suggested that aromatic abietanes such as retene were produced by aromatization of abietane-type diterpenoids in lacustrine sediments.
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