春季出水期におけるコムケ湖の水質変動解析と大気-海水間CO<sub>2</sub>フラックスの推定  [in Japanese] PREDICTION OF SPATIAL AND TEMPORAL VARIATION OF AIR-SEA CO<sub>2</sub> FLUX DURING SPRING FLOOD IN LAKE KOMUKE  [in Japanese]

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Abstract

本研究では,北海道コムケ湖の春季出水期における水質変動解析と大気-海水間CO<sub>2</sub>フラックスの推定を行った.はじめに,2013年春季のコムケ湖の現地観測データを用いて,塩分とDIC(溶存無機炭素濃度)の関係から生物過程(光合成,呼吸・分解等)による海水中CO<sub>2</sub>分圧への影響を検出し,その生物過程の有無や大小により,CO<sub>2</sub>分圧にどの程度影響を与えるかについて検討した.次に,3次元流動解析によりコムケ湖の再現計算を行い,湖内の流動および水質変動特性を把握した.最後に,生物過程を考慮した海水中CO<sub>2</sub>分圧と塩分の関係式から,海水中CO<sub>2</sub>分圧の湖内平面分布を求めるとともに,風速等の諸条件を与えたバルク法を用いて,コムケ湖全体の大気-海水間CO<sub>2</sub>フラックスの経時変化を推定した.

 In Lake Komuke, which is an important lagoon as carbon sinks, we analyzed previous data and found that salinity and biological metabolism (e.g., photosynthesis and respiration as shown by ΔDIC) are the two key environmental factors affecting CO<sub>2</sub> fugacity in the water column. Further, the data were analyzed using an approximate expression and the numerical computations using three-dimensional numerical model during spring flood to predict spatial and temporal variation of air-sea CO<sub>2</sub> flux. Results show that air-sea CO<sub>2</sub> flux changes into negative (i.e., absorption) when the lake is autotrophic with ΔDIC being < -100μmol/kg.

Journal

  • Journal of Japan Society of Civil Engineers, Ser. B3 (Ocean Engineering)

    Journal of Japan Society of Civil Engineers, Ser. B3 (Ocean Engineering) 72(2), I_982-I_987, 2016

    Japan Society of Civil Engineers

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