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In recent years, the issue of ocean acidification with the increase of atmospheric CO2 concentration came to be greatly taken up. Therefore, in addition to long-term prediction using a numerical simulation, CO2 exposure experiments in laboratory and field mesocosm have been carried out. However, in real ocean, it is extremely difficult to produce the low pH/high CO2 environment and to observe it. On the other hand, large amounts of CO2 (liquid CO2 and/or gaseous CO2) are being supplied to the ocean by the hydrothermal activity as a natural phenomenon. The low pH/high CO2 environment in the ocean derived from the hydrothermal activity is the only field for observing the ocean environments already acidified and/or acidifying. I have been observing the low pH/high CO2 environment in the ocean by surveying the dissolution and diffusion behaviors of the CO2 supplied from the hydrothermal activity as a natural analogue. I applied the pH/pCO2 sensor which I developed originally for observation. This sensor was put on the ocean observing platforms such as ROV or AUV and performed mapping observation and vertical observation. In the Hatoma Knoll at the Okinawa Trough and the NW Eifuku submarine volcano at the Mariana Trough of 1500 m water depth, CO2 droplets are spouting to the ocean from the sea floor and the depreciation of pH 0.2 ~ 1.0 was observed. In the Kagoshima Bay of 200 m water depth, gaseous CO2 is emitted to the bottom water of the bay and pH 5.5 ~ 6.0 in the bottom water ware detected. In the shallow hot springs of 20 m water depth at the off Taketomi Island, pH 6.5 ~ 7.0 in the water around the springs were searched.


Shitashima, K., Tokyo University of Marine Science and Technology, Japan,


Poster presentation

Session #:056
Date: 03/01/2017
Time: 11:00 - 12:00
Location: Poster/Exhibit Hall

Presentation is given by student: No

PosterID: 472