ECOSYSTEM MODEL 'DONGRI' STUDY ON THE EFFICIENCY AND THE LEAKAGE OF CO_2 SEQUESTRATION

摘要

The purpose of this paper is to evaluate the effectiveness of CO_2 sequestration including ocean-air CO_2 communication and the effects of injected depth/area and biochemical processes on the effectiveness of CO_2 sequestration. On the estimation, the ecosystem model, "DONGRI", comprised of the ocean and air system including physical and biological processes and being able to consider biochemical response to the impact of the sequestration, was used. First, we defined the Efficiency and the Leakage of the Sequestration (ES and LS) which have the possibility to be applied not only to ocean but also to other media's sequestration. From the results, ES rapidly decreased during early times from injection regardless of injection depth/area or from perfect sequestration (with no leakage), because of pCO_2 decrease in atmosphere which lead to weaker CO_2 absorption (CO_2 flux from air to sea) on sea surface. This result indicates that consideration of ocean-air communication has a possibility to become an important factor on ES of all methods of sequestration, depending on how to estimate/consider the efficiency of the sequestration. The ES/LS response to the ecosystem change due to the global warming/sequestration mainly comes from the differences of CaCO_3 dissolution and photosynthesis.