The fate of CO₂ bubble leaked from seabed

A numerical model of an individual CO₂ bubble dissolution and ascent in shallow seawater was developed to simulate the fate of CO₂ leaked from seabed naturally or artificially. The model consists of a solubility sub-model of CO₂ gas in seawater, a CO₂ bubble mass transfer sub-model, and a CO₂ bubble momentum transfer sub-model. The model is applied to predict the dynamics of leaked CO₂ in seawater at various depths from 0-150 m (temperature from 10 ^{{ring operator}}C to 25 ^{{ring operator}}C) and for initial bubble sizes from 3.0 to 40.0 mm in diameter. A diagram of CO₂ ascending distance vs dissolution time is obtained from model simulations. It is found that CO₂ bubbles ascend at a mean speed of 16 cm/sec and a mean shrinking rate of 30 × 1 0^{- 3} mm/s in diameter approximately if leaked from a shallow ocean (<150 m) seabed. A parameter, named as critical depth, is defined and suggested as a parameter to indicate if the CO₂ leaked from seabed can return to atmosphere. This critical depth is approximately linearly related to the initial bobble size with a gradient of -0.68 m/mm under seawater conditions in the simulation ocean. © 2009 Elsevier Ltd. All rights reserved.