To study greenhouse gas, researchers take the ferry

Federal scientists hitch a ride on UNC water-tracking studies

Staff WriterSeptember 30, 2010 

— Clues about how the earth responds to climate change may soon emerge from the lower decks of the Floyd J. Lupton and other ferries sailing along the North Carolina coast.

In the ferries' hot, noisy engine rooms, instruments for measuring the greenhouse gas carbon dioxide will join sensors and collection bottles that have been used for years to monitor vital signs of the Neuse River and Pamlico Sound.

Knowing how much gas Pamlico Sound absorbs and how much it gives off, when combined with all the other information collected about the water, will enhance the picture of how some of the most vibrant bodies of water on Earth react to climate change.

Hans Paerl, a professor at the UNC Institute of Marine Science, is leading an effort to learn the value of the Pamlico Sound and other coastal waters in absorbing greenhouse gases. Data gathered about the Pamlico will be stored for scientists worldwide who want to see how the sound responds.

In the Pamlico, life thrives in the mix of saltwater and freshwater. The sound is rich in tiny plants that soak up carbon dioxide, a gas that in excess contributes to warming of Earth's atmosphere, scientists say. Waterborne plants release greenhouse gases when they decompose.

Paerl compares the Pamlico and other coastal waters to the importance of rainforests in soaking up greenhouse gas.

Scientists are interested not only in activities that produce carbon dioxide, but in places such as forests and farms that absorb the gas. For years, research ships and commercial vessels have been used to measure how much carbon dioxide oceans absorb.

But not nearly as much is known about near-shore areas, where the immediate effect of human activities are felt most intensely on water quality, Paerl said.

"We know less about coastal systems and how important they are," he said.

Climate change is a hot research topic for the National Science Foundation, which gave grants totaling $500,000 to Paerl and other researchers to find out what's happening in the Pamlico.

"This is one of the new breaking stories in terms of research," said David Garrison, program director for biological oceanography at the National Science Foundation in Arlington, Va.

Way ahead of the feds

UNC had a head start getting a program going, Paerl said, because it's been using North Carolina ferries for nearly a decade to watch the water. The testing program started in 2000, the year after Hurricane Floyd inundated the Pamlico with freshwater runoff and sewage.

Instruments continuously record the water's temperature, saltiness, acidity, and levels of the pigment that makes plants green. Jugs collect water samples that are examined in Morehead City labs. The equipment travels three ferry routes: the short jaunt between Cherry Branch and Minnesott Beach, and the longer two-hour-plus trips between Ocracoke and Cedar Island, and between Ocracoke and Swan Quarter.

On a recent trip to Minnesott Beach, institute technicians put on ear protectors and headed into the Lupton's engine room, while passengers gazed at the shore, oblivious to the science happening beneath their feet.

Information about water conditions streams to computers in the boat's pilot house and at the Morehead City institute almost as soon as it's gathered. In-person visits are needed every week or two to retrieve water samples and to switch out the sensors that get clogged with gunk. The bundle of facts will eventually help scientists figure out what happens to gas uptake when, for example, pollution causes the overgrowth of the tiny plants.

Since June 2009, Joseph Crosswell, a graduate student at the institute, as been testing the carbon dioxide sensor by periodically taking it on trips up the Neuse River on a 25-foot boat.

The carbon dioxide gear will start its ferry rides in early November. Having equipment that measures carbon dioxide on the day and night ferry runs will produce a more complete picture than drawing water periodically from a few spots on the sound.

"The estuary is so dynamic from one point to another," Crosswell said. "This helps us see overall how the system breathes day in and day out."

The ferries don't cover the whole 80-mile-long sound. So Michael Wetz, a marine scientist in Texas, plans to use satellite imagery and the ferries' scans to see what's happening in the entire sound. Wetz, who used to work with Paerl in Morehead City, also worked with scientists in the U.S. Environmental Protection Agency in Research Triangle Park on using information from satellites for water quality measurements.

Team members said discoveries about the Pamlico can be translated to similar water systems around the country. Through the National Science Foundation, their discoveries will be available to scientists around the world.

"I think that what we'll find will be applicable to other systems," Wetz said. "The results will go beyond the Neuse-Pamlico." or 919-829-4821

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