Christopher Barry, has an article on OTEC and CO2 sequestration at RenewableEnergyWorld.com. This article also discusses the subject of dissolved CO2 in the deep water which is being brought up by an OTEC system.
We have a paper from 1989, Carbon dioxide release from OTEC cycles, by Herbert J. Green and Peter R. Guenther that discusses this issue, in the OTEC Library.