Mass transfer processes of a hydrate-covered deep CO2 lake

By means of an autoclaved, hydrodynamically calibrated flux chamber, the mass transfer coefficient kCO2kCO2 of carbon dioxide CO2 across a smooth hydrate–seawater interface is determined for friction velocities <1 cm s−1 at 30 and 40 MPa and 2–4 °C. In contrast to methane, kCO2kCO2 follows mixed-convection laws, requiring for increasing friction velocity u* metastable saturation values. At values u* > 0.4 cm s−1, mechanical strain on the hydrate film may generate an added hydrate debris or microdrop entrainment function. A quantitative data reduction chain is applied which shows that for the tidal range tested, mass transfer coefficients lie in the range 3×10−6