HR: 0800h
AN: V21D-0755    [Abstracts]
TI: Emission of CO2 from seafioor hydrothermal systems at Mariana Trough
AU: Maeda, Y
EM: ymaeda@ceresco.jp
AF: CERES, Inc., 1646, Abiko, Abiko, 2701166, Japan
AU: * Shitashima, K
EM: shita@criepi.denken.or.jp
AF: Central Research Institute of Electric Power Industry, 1646, Abiko, Abiko, 2701194, Japan
AB: Hydrothermal vent fluids are highly enriched in CO2 and the CO2 rich fluids are released into the ocean as a hydrothermal plume. Especially, the emission of hydrothermal-related liquid CO2 from the seafloor (about 1500m) was discovered at the Okinawa Trough and Mariana Trough. At these areas, it is considered that the liquid CO2 rises up to shallow depth as a CO2 droplet and that the rising CO2 droplet dissolves gradually in ambient seawater. The observation of the hydrothermal-related CO2 would provide the opportunity for understanding the physic-chemical behavior and diffusion process of liquid CO2 in the ocean. Newly developed in-situ pH/pCO2 sensor can detect precisely and rapidly the changes of pH and pCO2 derived from high CO2 concentration. At southern Mariana Trough, the pH/pCO2 sensor was installed onto the manned submersible and in-situ pH and pCO2 data were measured every 10 seconds during the operation on the hydrothermal active site. Mapping survey of low pH and pCO2 distribution was performed on the hydrothermal active site by the grid navigation of the manned submersible that installed the pH/pCO2 sensor. The results of pH mapping survey showed only localized pH depression at the hydrothermal active site. At NW Eifuku submarine volcano, hydrothermal-related liquid CO2 dispersion was observed by using a towing multi-layer monitoring system. This system can observe the dispersion behavior of CO2 by towing several in-situ pH/pCO2 sensors and SSBL transponders in the high CO2 plume. Low pH plume of 100m high and 200m wide was detected above the summit of NW Eifuku submarine volcano.
DE: 0428 Carbon cycling (4806)
DE: 1030 Geochemical cycles (0330)
DE: 1034 Hydrothermal systems (0450, 3017, 3616, 4832, 8135, 8424)
DE: 1050 Marine geochemistry (4835, 4845, 4850)
DE: 4825 Geochemistry
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting