In modeling disposal and sequestration of anthropogenic CO, in the deep ocean, one of the complicated phenomena encountered is formation of a thin solid hydrate layer at the interface of the disposed liquid CO, and seawater. Recently, P. C. Lund published several -articles on formation and stability of the hydrate layer (or film in Lund's articles) which is believed to form at the surface of a "CO, lake" resulted from disposal of liquid CO, in the deep Ocean [ 1 -31. The basic assumptions in these analyses are: (1) water diffuses into liquid CO, and reacts with CO, to form hydrates in the liquid CO, phase; (2) the rapidly formed hydrate inhibits the further liquid-liquid diffusion which results in a thin hydrate layer at the interface; the hydrate layer is dense and impermeable; and
(3) the hydrate layer decays in water making the liquid-liquid diffusion regained and thus the hydrate layer is reformed. The key parameters in the modeling, such as diffusion coefficients of CO, in water and water in CO, as well as rate constants for hydrate formation and decay, were obtained from correlating the shrinkage rate data for a CO, droplet which, according to the experiments of North et al. [4], is significantly different from the semiinfinitely large CO, reservoir that Lund studied.
Assumptions that Lund's analyses are based on may be challenged on the following ground: (1) The mole fraction of water in CO, hydrate, CO2-.5.75H,O, is 85% while the measured solubility of water in liquid CO, is less than 0.5% which in-