Undersea methane could be contributor to increased ocean acidity, researchers find

Dec 07, 2010

(PhysOrg.com) -- A North Carolina State University researcher is part of a team which has found that methane from “cold seeps” – undersea areas where fluids bubble up through sediments at the bottom of the ocean – could be contributing to the oceans’ increasing acidity and stressing already delicate undersea ecosystems.

Oceanic microorganisms and bacteria survive by consuming dissolved organic carbon, or DOC. A byproduct of this consumption is CO2 – – which, in large enough concentrations, makes seawater more acidic.

Dr. Chris Osburn, assistant professor of marine science at NC State, and a research team led by geologists from the U.S. Geological Survey found high levels of methane-derived DOC in the deep water over cold seeps in two areas of the Pacific Ocean. Their findings appear online in Nature Geoscience.

“Normally, DOC primarily comes from the degradation of phytoplankton (algae), or from river discharge into the ocean,” Osburn says. “Finding DOC that comes from is a new part of the carbon cycle that hasn’t really been accounted for.”

Now that they have found methane-derived DOC, the researchers need to determine if it is found in other cold seeps worldwide, and whether or not it is labile, or easily used by the microorganisms that survive on DOC.

“Based on what we found, up to 30 percent of the Pacific Ocean’s deep water DOC could be methane-derived,” Osburn says. “If it is utilized by marine microorganisms, methane-derived DOC could be a component of deep ocean ecosystems. Moreover, microbial processing of this DOC could be contributing to increased CO2 in the deep ocean and thus to acidification.”

Explore further: Images released of shipwreck in San Francisco Bay

More information: www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1016.html

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User comments : 2

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Sancho
not rated yet Dec 08, 2010
Methane seeps also affect atmospheric CO2 concentrations. Yet it is not accounted for in the IPCC models.
3432682
not rated yet Dec 08, 2010
There is massively more methane already in methane hydrates. They have not caused a problem with acidic seawater. I have found no reason to believe that oceans could become acidic, or that the tiny changes possible would be harmful. The oceans are slightly base, not acidic. Articles which discuss possibilities of harmful effects ought to at least mention opposing or mitigating factors, in order to be balanced and forthright.

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