2009 年 21 巻 2 号 p. 2_1-2_13
CO2 oceanic sequestration is one of the technologies for reducing the discharge of CO2 into the atmosphere, which is considered to cause the global warming, and consists in isolating industry-made CO2 gas within the depths of the ocean. This method is expected to enable industry-made CO2 to be separated from the atmosphere for a considerably long period of time.
On the other hand, it is also feared that the CO2 injected in the ocean may lower pH of seawater surrounding the sequestration site, thus may adversely affect marine organisms.
For evaluating the biological influences, we have studied to precisely predict the CO2 distribution around the CO2 injection site by a numerical simulation method.
In previous studies, in which a 2 degree by 2 degree mesh was employed in the simulation, CO2 concentrations tended to be evenly dispersed within the grid, giving lower concentration values. Thus, the calculation accuracy within the area several hundred kilometers from the CO2 injection site was not satisfactory for the biological effect assessment.
In the present study, we improved the accuracy of concentration distribution by changing the computational mesh resolution for a 0.2 by 0.2 degree.
By the renewed method we could obtain detailed CO2 distribution in waters within several hundred kilometers of the injection site, and clarified that the Moving-ship procedure may have less effects of lowered pH on marine organisms than the fixed-point release procedure of CO2 sequestration.