Researchers Find Acidified Ocean Water

Evidence of corrosive water caused by the ocean's absorption of carbon dioxide (CO2) was found less than 20 miles off the West Coast of North America during a field study from Canada to Mexico last summer. This was the first time "acidified" ocean water has been found on the continental shelf of western North America.

The term "ocean acidification" describes the process of ocean water becoming corrosive as a result of carbon dioxide being absorbed from the atmosphere.

"Acidification of the Earth's ocean water could have far-reaching impacts on the health of our near-shore environment and the sustainability of ecosystems that support human populations through nourishment and jobs," said Richard W. Spinrad, National Oceanic and Atmospheric Administration assistant administrator for oceanic and atmospheric research. "This research is vital to understanding the processes within the ocean, as well as the consequences of a carbon-rich atmosphere."

The findings were published May 22 in the online journal Science Express. "Evidence for Upwelling of Corrosive 'Acidified' Water onto the Continental Shelf" was written by Richard A. Feely and Christopher Sabine, both oceanographers at NOAA's Pacific Marine Environmental Laboratory in Seattle, Wash.

"Our findings represent the first evidence that a large section of the North American continental shelf is seasonally impacted by ocean acidification," said Feely. "This means that ocean acidification may be seriously impacting marine life on our continental shelf right now."

"While this absorption provides a great service to humans by significantly reducing the amount of greenhouse gases in the atmosphere and decreasing the effects of global warming, the change in the ocean chemistry affects marine life, particularly organisms with calcium carbonate shells, such as corals, mussels, mollusks, and small creatures in the early stages of the food chain," said Feely.

The study was the first in what is planned to be a biennial sequence of observations and studies of carbon. The researchers participated in the North American Carbon Program West Coast Cruise on the R/V Wecoma, owned by the National Science Foundation and operated by Oregon State University. The international scientific team plans to continue their studies of ocean acidification in follow-up cruises in late 2009.

Previous studies found ocean acidification at deeper depths farther from shore. The researchers said that the movement of the corrosive water appears to happen during the upwhelling season during the spring and summer, when winds bring CO2 -rich water up from depths of about 400-600 feet onto the continental shelf. The water that upwells off of the North American Pacific Coast has been away from the surface for about 50 years.

The field study collected samples from Queen Charlotte Sound, Canada, to San Gregorio Baja California Sur, Mexico. The closest they found corrosive water was about four miles off of the northern California coast.

"We did not expect to see this extent of ocean acidification until the middle to the end of the century," said Sabine. "Because of this effort, we have a baseline for future observations as we continue to study and monitor the relationship of biological and physical processes and their ability to respond to ocean acidification."

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