GMD Seminars
For questions about GMD seminars, contact Irina Petropavlovskikh, Phone: (303) 497-6279 or Ann Thorne, Phone: (303) 497-4600. Visitors from outside the NOAA campus need to contact Irina or Ann at least one day before the seminar date to be added to the visitor's list at the security gate.

*NEW Additional Requirement for Visitors:* Names of all off-site visitors without a U.S. government issued ID badge must be collected and submitted to security in advance of every seminar. Please call Ann Thorne at 303-497-4600 (leave a message including your name) or send an e-mail to Irina Petropavlovskikh by the day before the seminar if you plan to attend.

Speaker: John Lupton, NOAA Pacific Marine Environmental Laboratory, Newport, Oregon
Date/Time: Friday, October 3, 2008 10:00AM
Location: Multi-purpose Room (GC-402) David Skaggs Research Center (DSRC) NOAA Building, DOC Boulder Campus
Title: Natural CO2 from Submarine Hydrothermal Systems

ABSTRACT
Although dozens of mid-ocean ridge (MOR) hydrothermal systems have been studied over the past few decades, a significant discharge of a pure gas phase has been found at only one site on the Explorer Ridge, northeast Pacific. In contrast to MOR systems, recent studies of submarine volcanoes on volcanic arcs have found several sites that, in addition to discharging hot vent fluid, are also venting a separate CO2 -rich phase either in the form of gas bubbles or liquid CO2 droplets. Submersible dives on 22 active submarine volcanoes on the Mariana and Tonga-Kermadec Arcs have discovered systems on 6 of these volcanoes that are venting a free gas phase in addition to hot vent fluids.

This talk will focus on the Champagne vent field on NW Eifuku volcano in the northern Mariana Arc, which is discharging cold droplets of liquid CO2 as well as hot gas-rich vent fluid. The other 5 volcanoes in this study are shallower and therefore the free gas discharge takes the form of gas bubbles rather than liquid CO2 droplets. At NW Eifuku, collecting samples of the liquid CO2 droplets required the development of special sampling technology that could be deployed from a robotic submersible. The carbon flux from this small vent field is quite large, estimated at 23 moles/s, about 0.1% of the global mid-ocean ridge carbon flux. Detailed analysis of the helium and carbon discharging at the Champagne site has provided clues to the origin of this high carbon flux. One follow-up biological study at NW Eifuku has shown that the mussels at the Champagne site are drastically affected by the low pH environment. Thus these CO2 -rich systems may be important natural laboratories for studying the effects of high CO2 concentrations on marine ecosystems, with relevance to ocean acidification and seabed sequestration of anthropogenic carbon.