News Release

Yellowstone Mudpots Produce More Carbon Dioxide Than Expected

Peer-Reviewed Publication

Penn State

San Francisco, Calif. -- While the caldron-like bubbling of active mudpots may be the most eyecatching phenomenon in the Mud Volcano portion of Yellowstone National Park, Penn State researchers have discovered that nascent and dying mudpots actually produce equivalent amounts of carbon dioxide.

"We know that geothermal systems put a lot of carbon dioxide into the atmosphere," says Cindy Werner, graduate student in geosciences. "Up until now, researchers have estimated the amounts of naturally released carbon dioxide by counting and evaluating active volcanos."

Carbon dioxide is a greenhouse gas that contributes to global warming. Estimating the amounts of naturally occurring carbon dioxide can help scientists determine the contribution of humans to global carbon dioxide.

Using a statistically designed sampling method, Werner and Dr. Susan Brantley, professor of geosciences, investigated the northeastern section of Yellowstone for carbon dioxide out gassing. Their method was based on measured emissions rather than any visual cues in the area.

"Until recently, we assumed that active mudpots would be the locations of most of the carbon dioxide degassing," Werner told attendees today (Oct. 11) at the fall meeting of the American Geophysical Union. "We have found that you cannot let your senses bias the research, especially with a gas that cannot be seen or smelled and that does not, in itself, destroy vegetation."

Most of the carbon dioxide measured by the Penn State team was not related to vents -- active mudpots. Some visually inactive areas gave off as much as 32,000 grams per square meter per day of carbon dioxide while crop areas produce usually less than 30 grams per square meter per day and healthy forest only 20 grams per square meter per day.

Yellowstone is famous for its volcanic activity with geysers -- vents of steam created when underground magma heats the earth beneath groundwater until steam is forced explosively upward -- the best known. However, geysers make up only a small portion of the activity in the Yellowstone caldera, formed by the Lava Creek eruption some 650,000 years ago.

Mudpots are found in the northeastern acid sulfate area of the park and form when gases rise to the surface and sulfur compounds mix with water to form highly acidic solutions that dissolve the rocks. These bubbling pools are not boiling, although most mudpots are hot. Escaping gases causes the activity in the same way a bottle of soda will bubble over if shaken.

The volcanic activity at Yellowstone is similar to that in the Hawaiian Islands and is due to a hot spot beneath the Earth's crust. This differs from the vulcanism seen at Mt. St. Helens in the Cascade Mountains, which occurs when one tectonic plate moves beneath another and the edge of the plate forms a molten region.

"We know that Yellowstone is a hot spot volcanic region and the helium isotopes there have a signature similar to that of the volcanos in Hawaii, rather than the crustal volcanos in the Cascades," says Werner.

One area where the researchers found high levels of carbon dioxide was a grassy field surrounded by healthy forest. The area did not look like a mudpot, but closer examination and soil samples indicated that it had been a mudpot in the past and was filled in.

Earthquakes, which are prevalent in the area, can cause the pathways for escaping gases to alter and mudpots come and go.

Other areas with unexpectedly high levels appeared to be new mudpots in their early stages. Both nascent and dying mudpots can produce more carbon dioxide than active mudpots.


EDITORS: Ms. Werner may be reached at (814) 863-7516 or werner@farallon.geosc.psu.edu by email. Dr. Brantley may be reached at (814) 863-1739 or brantley@geosci.psu.edu by email.


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