A methodology has been developed to quantify mortality suffered by marine zooplankton passing through a CO2-enriched sea water plume. Predicted impact depends on the mode of injection with scenarios which disperse the CO2 showing least impact. Benthic impacts also depend on injection mode, with localized effects expected for any scenario in which the plume contacts the bottom. Effects of scale were found whereby the predicted impact from 10 power plants is greater than 10 times the impact of one plant at the same site. Based on available data, our modeling suggests that mortality associated with exposure to low pH can be avoided by properly dispersing the CO2 and keeping the plume off of the seabed.