Studies on potential relations between methane hydrate destabilization/methane gas emission and environmental fluctuations in Lake Baikal, Russia

2023 Fiscal Year Final Research Report

• Project/Area Number: 20H04304
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 63010:Environmental dynamic analysis-related
• Research Institution: Kitami Institute of Technology
• Principal Investigator: MINAMI Hirotsugu 北見工業大学, 工学部, 教授 (40241426)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: メタンハイドレート / バイカル湖 / 環境変動 / メタンハイドレートの分解 / 温室効果ガスの放出

Outline of Final Research Achievements

Lake Baikal, Russia, is the only freshwater lake in which methane hydrates (MHs) have accumulated in subsurface sediments. International collaborative research projects were conducted by scientists from Japan, Russia and Belgium to study subsurface MH formation/dissociation.
Subsurface MHs were retrieved at a mound-like bottom area off eastern coast of the central basin. The pressure-temperature condition at the MH-bearing area was, however, slightly out of the MH-stability conditions. This finding suggests that the MHs at the area have been in the process of dissociating since decrease in the water level and/or increase in water/sediment temperature. The fact that methane gas emissions from the lake floor were observed at the area supports aforementioned interpretation.
All results obtained during this study suggest potential relations between MH destabilization/methane gas emission and environmental fluctuations at the studied area.

Free Research Field

分析化学

Academic Significance and Societal Importance of the Research Achievements

世界で唯一MHの存在が確認されている淡水湖であるバイカル湖において、環境変動によるMH分解と温室効果ガスの放出に関する機構解明を目的に、日本-ロシア-ベルギーの国際共同研究を実施した。
水温と水深から算出されるMH安定領域からわずかに外れた条件下にMH存在が確認された事実は、MH生成後の環境変動を示唆する。湖面水位が現在より1 mほど高ければ計算上MHは安定であり、その当時に生成したMHが水位低下で分解しつつあるとの解釈が可能である。温暖化など地球規模の環境変動が指摘される中、天然MHの存在環境の変化と生成および分解機構の理解は学術的・社会的に重要である。