ECOSYSTEM MODEL STUDY ON LONG-TERM DYNAMICS OF DISSOLVED OXYGEN AND ITS FACTORS AT THE BOTTOM WATER IN TOKYO BAY
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- SOHMA Akio
- 大阪市立大学大学院 工学研究科都市系専攻
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- HARUTA Takuro
- 大阪市水道局 南部水道センター 配水管工事グループ 元大阪市立大学大学院 工学研究科都市系専攻
Bibliographic Information
- Other Title
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- 東京湾における海底溶存酸素濃度の経年変化とその要因 ～生態系モデル解析～
- トウキョウワン ニ オケル カイテイ ヨウゾンサンソ ノウド ノ ケイ ネンヘンカ ト ソノ ヨウイン : セイタイケイ モデル カイセキ
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Abstract
Hypoxia has been improving throughout Tokyo Bay, however, there are still seriously hypoxic areas. In this study, we analyzed the secular change of dissolved oxygen (DO) and consumption mechanism of the sea-floor due to reduction of nutrients and COD inflow from the land from 1979 to 2009, using the benthic-pelagic coupled ecosystem model, EMAGIN-H.P. As a result, the model demonstrated that there were at least three types of areas: zone A, in which DO increases; zone B, in which DO turns from a decrease to an increase; and zone C, where DO decreases. In addition, reduction of nutrients and COD inflow leads to (1) decrease of reduced substances (Mn2+, Fe2+, S2-) and increase of benthic fauna due to improvement of hypoxia at zone A, (2) decrease of reduced substances due to DO increase and decrease of benthic fauna due to food shortage at zone C, and (3) increase of benthic fauna until 1994 with the improvement of hypoxia and then a decrease due to food shortage at zone B. These results show that the optimal amount of nutrients and COD inflow in view of both the increase of benthic fauna and the improvement of hypoxia differs from area to area.
Journal
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- Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering)
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Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering) 74 (2), I_1273-I_1278, 2018
Japan Society of Civil Engineers