What first appeared to be effervescent bubbles, like those in champagne, rising from a hydrothermal vent area in the northern Mariana Arc of the Pacific Ocean turned out to be liquid carbon dioxide. This is only the second location where the phenomenon has been identified. Scientists from the National Oceanic and Atmospheric Administration and its partner institutions made the discovery during an April 2004 expedition. NOAA is an agency of the U.S. Department of Commerce.
The findings and analysis of that expedition were presented today at the annual meeting of the American Geophysical Union in San Francisco.
“Out of the hundreds and hundreds of known hydrothermal areas, it was an exciting discovery to find another location with liquid carbon dioxide,” said John Lupton, an oceanographer at NOAA’s Pacific Marine Environmental Laboratory in Seattle. The only other reported area is in the Okinawa Trough in the Pacific Ocean.
The finding of liquid carbon dioxide will help scientists as they study the effects of carbon dioxide rich waters on organisms living in those waters. A study this summer reported on laboratory experiments where the shells of calcium-carbonate creatures dissolved in carbon dioxide rich waters.
“In the Mariana Trench, we found a natural laboratory where the effects of carbon dioxide on marine organisms can be studied,” said Steve Hammond, acting director of NOAA’s Office of Ocean Exploration. “Discoveries such as this help NOAA improve its understanding of ecosystems, which is one of its four mission goals.”
The expedition used the remotely-operated vehicle ROPOS. Scientists could see milky gas-rich fluid coming out of a couple of the small chimneys at a site near the summit of Northwest Eifuku, a submarine volcano in the northern Mariana Arc.
Lupton noted that there were two fluids coming up from the vent sites: a hot vent fluid measuring 217-degrees Fahrenheit coming from the chimneys or smokers, and the cooler liquid droplets coming from other parts of the vent field.
Samples were collected for further analysis, although the scientific team was fairly confident that the fluid was predominately carbon dioxide.
“The droplets were sticky and they didn’t join together to make larger bubbles,” Lupton recalled. “Although we were pretty sure it was liquid carbon dioxide, we wanted to analyze the samples to make sure.”
That analysis determined that the cold droplets were composed of about 90 percent carbon dioxide, and that the amount of carbon dioxide in the hot vent fluid liquid was a surprising 2.3 moles of carbon dioxide per kilogram of water, or about 60 liters of gaseous carbon dioxide per kilogram of water.
“This was an order of magnitude higher than any carbon dioxide values previously reported,” Lupton said.
Lupton noted that there are plans by scientific teams in the U.S., Germany, and Japan to revisit the site in 2005 and 2006 to conduct more research.
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On the Web:
Read about the expedition at: http://oceanexplorer.noaa.gov/explorations/04fire/logs/april10/april10.html
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