底質の安定同位体比を指標とした子吉川の水環境評価  [in Japanese] Evaluations of Aquatic Environment in Koyoshi River Watershed Using Analysis of Stable Isotope Ratios in Sediment  [in Japanese]

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Author(s)

    • 金澤 伸浩 KANAZAWA Nobuhiro
    • 秋田県立大学システム科学技術学部経営システム工学科 Department of Management Science and Engineering, Faculty of System Science and Technology, Akita Prefectural University
    • 齋藤 修成 SAITO Syusei
    • 秋田県立大学システム科学技術学部経営システム工学科 Department of Management Science and Engineering, Faculty of System Science and Technology, Akita Prefectural University
    • 漆川 芳國 URUSHIGAWA Yoshikuni
    • 秋田県立大学システム科学技術学部経営システム工学科 Department of Management Science and Engineering, Faculty of System Science and Technology, Akita Prefectural University

Abstract

The stable isotope ratios of carbon (δ<sup>13</sup>C) and nitrogen (δ<sup>15</sup>N) in sediment and water quality were monitored in the Koyoshi River watershed in Akita, Japan and used in describing the change in water quality and nitrogen balance in the watershed. Although the degree of organic pollution had worsened downstream (DOC: 2.0 mgC · <I>l</I><sup>-1</sup> to 2.8 mgC · <I>l</I><sup>-1</sup>; NO<sub>3</sub><sup>-</sup>-N: 0.22 mg · <I>l</I><sup>-1</sup> to 0.31 mg · <I>l</I><sup>-1</sup>), the values of δ<sup>15</sup>N and δ<sup>13</sup>C downstream (1.5 ‰ and -26.3 ‰, respectively) were lower than those in the upper river basin (3.2 ‰ and -24.0 ‰, respectively). It was deduced that there have been nitrogen loading in the upper river basin and that humic substances have contributed to the decrease in the isotope ratios in the middle basin. The seasonal variation in δ<sup>15</sup>N in sediment indicates the influence of fertilizer applied in rice fields. The amount of nitrogen removal from water was estimated by isotope fractionation analysis with ammonium concentration and δ<sup>15</sup>N in sediment, and found to be reasonable considering the estimated amount of fertilizer normally applied in rice fields.

Journal

  • Journal of Japan Society on Water Environment

    Journal of Japan Society on Water Environment 31(1), 53-58, 2008-01-10

    Japan Society on Water Environment

References:  28

Codes

  • NII Article ID (NAID)
    10020129728
  • NII NACSIS-CAT ID (NCID)
    AN10372439
  • Text Lang
    JPN
  • Article Type
    ART
  • ISSN
    09168958
  • NDL Article ID
    9338614
  • NDL Source Classification
    ZN5(科学技術--建設工学・建設業--都市工学・衛生工学)
  • NDL Call No.
    Z16-1045
  • Data Source
    CJP  NDL  J-STAGE 
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