Dynamic morphology of gas hydrate on a methane bubble in water: Observations and new insights for hydrate film models

• Published in: Geophysical research letters 2014-10, Vol.41 (19), p.6841-6847
• Main Authors: Warzinski, Robert P., Lynn, Ronald, Haljasmaa, Igor, Leifer, Ira, Shaffer, Frank, Anderson, Brian J., Levine, Jonathan S.
• Format: Article
• Language: English
• Subjects: Air pollution; Anthropogenic factors; Atmosphere; Atmospheric models; bubble hydrodynamics; Bubbles; Budgeting; Budgets; Coating; Coatings; Computational fluid dynamics; Computer simulation; Deep sea; Deep water; Dissociation; Dissolution; Dissolving; Eruptions; Fluid flow; Fluid mechanics; Formations; Gas hydrates; Gases; Greenhouse gases; Human influences; hydrate film modeling; hydrate morphology; Hydrates; hydrocarbon transport; Hydrocarbons; Hydrodynamics; marine seeps; Methane; Morphology; Ocean warming; ocean/atmospheric gas partitioning; Plume models; Sea ice; Seawater; Survival; Transit; Transport; Transportation models; Water; Water column
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1002/2014GL061665

Predicting the fate of subsea hydrocarbon gases escaping into seawater is complicated by potential formation of hydrate on rising bubbles that can enhance their survival in the water column, allowing gas to reach shallower depths and the atmosphere. The precise nature and influence of hydrate coatings on bubble hydrodynamics and dissolution is largely unknown. Here we present high‐definition, experimental observations of complex surficial mechanisms governing methane bubble hydrate formation and dissociation during transit of a simulated oceanic water column that reveal a temporal progression of deep‐sea controlling mechanisms. Synergistic feedbacks between bubble hydrodynamics, hydrate morphology, and coverage characteristics were discovered. Morphological changes on the bubble surface appear analogous to macroscale, sea ice processes, presenting new mechanistic insights. An inverse linear relationship between hydrate coverage and bubble dissolution rate is indicated. Understanding and incorporating these phenomena into bubble and bubble plume models will be necessary to accurately predict global greenhouse gas budgets for warming ocean scenarios and hydrocarbon transport from anthropogenic or natural deep‐sea eruptions. Key Points Complex surface mechanisms govern hydrate formation and dissociation on bubblesSurface hydrate morphology and coverage characteristics linked to hydrodynamicsNew mechanistic insights may have important implications for bubble plume models