Seifert, Richard, Nauhaus, Katja, Blumenberg, Martin, Krüger, Martin and Michaelis, Walter (2006) Methane dynamics in a microbial community of the Black Sea traced by stable carbon isotopes in vitro. Organic Geochemistry, 37 (10). pp. 1411-1419. DOI 10.1016/j.orggeochem.2006.03.007.

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Abstract

There is growing concern about the transfer of methane originating from water bodies
to the atmosphere. Methane from sediments can reach the atmosphere directly via bubbles
or indirectly via vertical turbulent transport. This work quantifies methane gas bubble
dissolution using a combination of bubble modeling and acoustic observations of
rising bubbles to determine what fraction of the methane transported by bubbles will
reach the atmosphere. The bubble model predicts the evolving bubble size, gas
composition, and rise distance and is suitable for almost all aquatic environments. The
model was validated using methane and argon bubble dissolution measurements
obtained from the literature for deep, oxic, saline water with excellent results. Methane
bubbles from within the hydrate stability zone (typically below 500 m water depth in the
ocean) are believed to form an outer hydrate rim. To explain the subsequent slow
dissolution, a model calibration was performed using bubble dissolution data from the
literature measured within the hydrate stability zone. The calibrated model explains the
impressively tall flares (>1300 m) observed in the hydrate stability zone of the Black
Sea. This study suggests that only a small amount of methane reaches the surface at active
seep sites in the Black Sea, and this only from very shallow water areas (<100 m). Clearly,
the Black Sea and the ocean are rather effective barriers against the transfer of bubble
methane to the atmosphere, although substantial amounts of methane may reach the
surface in shallow lakes and reservoirs.

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