Verification of the direct uptake of atmospheric CO2 by coastal macrophyte using carbon isotopes and chamber method

2022 Fiscal Year Final Research Report

• Project/Area Number: 19K20500
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 64050:Sound material-cycle social systems-related
• Research Institution: National Institute of Maritime, Port and Aviation Technology
• Principal Investigator: Watanabe Kenta 国立研究開発法人海上・港湾・航空技術研究所, 港湾空港技術研究所, 主任研究官 (20725618)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: 海草藻場 / 大気CO2吸収 / ブルーカーボン / CO2フラックス / アマモ / 沿岸域

Outline of Final Research Achievements

Recent studies have found that vegetated coastal habitats such as seagrass meadows can be a net sink for atmospheric CO2. This study aims to measure the direct CO2 uptake from seagrass leaves exposed to the atmosphere in seagrass meadows. I developed a transparent floating chamber that does not inhibit photosynthesis of seagrasses, and measured CO2 gas exchange rates in seagrass beds. The measurement results showed that seagrass meadows in the subarctic and temperate sites acted as CO2 sinks on a daily scale during summer. On the other hand, direct CO2 uptake was not detected as CO2 exchange rates. This study suggested that whether direct CO2 uptake by seagrasses contributes significantly to CO2 exchange rates or not may depend on the characteristics of the seagrass meadows (e.g., exposure time and length of exposed leaf).

Free Research Field

生物地球化学

Academic Significance and Societal Importance of the Research Achievements

海草等が大気に露出した際の直接的CO2吸収という未知の炭素フローの実測を行ったことは，学術的・社会的に意義のある成果と考えている．沿岸植生による大気CO2除去機能は気候変動緩和策への活用が期待されているが，大気CO2除去の過程には未だ評価できていない未知の炭素フローも残されている．ブルーカーボン生態系とも呼ばれる沿岸植生を大気CO2除去の目的で社会的に活用していく上では，こうした過程の解明を進めていく必要がある．