Estimation of Source Origins of Organic Matter Inducing Oxygen-Depleted Water in Coastal Seas Using Stable Isotope Ratios of Carbon

• KOBAYASHI Shiho

  Field Science Education and Research Center, Kyoto University

• FUJIWARA Tateki

  Professor Emeritus of Kyoto University

• KOMAI Yukio

  Osaka Institute of Technology

• TANAKA Shuhei

  Graduate School of Global Environmental Studies, Kyoto University

• SUZUKI Yuji

  Graduate School of Global Environmental Studies, Kyoto University

Bibliographic Information

Other Title

• 沿岸海域の貧酸素化を引き起こす有機物の起源推定：炭素安定同位体比を用いたアプローチ
• エンガン カイイキ ノ ヒンサンソカ オ ヒキオコス ユウキブツ ノ キゲン スイテイ : タンソ アンテイ ドウイタイヒ オ モチイタ アプローチ

Abstract

The method of estimating the source origin of the organic matter that consumes dissolved oxygen in an aquatic environment using carbon stable isotope (δ¹³C) of dissolved inorganic carbon (DIC) is effective because the method needs only a small portion of water and a brief duration. In an anoxic water mass in a low-lying depression in a port, δ¹³C-DIC decreases in accordance with the increase in the concentration of DIC (R²=0.93) ; and hence, δ¹³C of the organic matter that consumes dissolved oxygen can be estimated with considerable accuracy using the relationship between the concentration of DIC and δ¹³C-DIC. We demonstrated that the method of using in situ δ¹³C-DIC, which had been applied to lakes, performs effectively under the condition of continually decreasing pH in an anoxic water mass formed at the bottom of the sea. The contribution ratio of the phytoplankton-derived and land-derived organic matter was estimated using their δ¹³C values estimated in previous studies. As a result, 59-88％ of organic matter that consumes oxygen was estimated to originate from phytoplankton. Low-lying depressions in coastal seas, where the water exchange rate is significantly small, is suitable for examining remineralization processes of organic matter in coastal seas.

Journal

• Journal of Japan Society on Water Environment

  Journal of Japan Society on Water Environment 41 (1), 1-10, 2018

  Japan Society on Water Environment

Keywords

• Coastal seas
• Hypoxia
• Carbon stable isotope ratio
• Phytoplankton-derived organic matter
• Land-derived organic matter

Details

• CRID: 1390001205080881152
• NII Article ID: 130006307497
• NII Book ID: AN10372439
• DOI: 10.2965/jswe.41.1
• ISSN: 18813690
• ISSN: 09168958
• NDL BIB ID: 029401731
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I029401731
• Web Site: https://www.jstage.jst.go.jp/article/jswe/41/1/41_1/_pdf
• Text Lang: ja
• Data Source:
  • JaLC
  • NDL
  • Crossref
  • CiNii Articles
  • KAKEN
• Abstract License Flag: Disallowed