The biological impact on the ambient marine environment should be assessed in the CO2 injection at the intermediate depth. The long term dispersion (several decades) will also have a potential impact on the marine ecosystem in the wide area. The velocity field and dispersion of the substance in the North Pacific ocean at the intermediate depth were computed using an OGCM, and discussed with the comparison with the observed temperature, salinity and CFCs profiles. A model was applied to estimate the diffusion of the artificially injected CO2.