Savannah, Ga. – While climatologists are carefully watching carbon dioxide levels in the atmosphere, another group of scientists is exploring a massive storehouse of carbon that has the potential to significantly affect the climate change picture.
University of Georgia Skidaway Institute of Oceanography researcher Aron Stubbins is part of a team investigating how ancient carbon, locked away in Arctic permafrost for thousands of years, is now being transformed into carbon dioxide and released into the atmosphere. The results of the study were published in Geophysical Research Letters.
“However, if you allow your food to defrost, eventually bacteria will eat away at it, causing it to decompose and release carbon dioxide,” Stubbins said. “The same thing happens to permafrost when it thaws.”The Arctic contains a massive amount of carbon in the form of frozen soil—the remnants of plants and animals that died more than 20,000 years ago. Because this organic material was permanently frozen year-round, it did not undergo decomposition by bacteria the way organic material does in a warmer climate. Just like food in a home freezer, it has been locked away from the bacteria that would otherwise cause it to decay and be converted to carbon dioxide.
Scientists estimate there is more than 10 times the amount of carbon in the Arctic soil than has been put into the atmosphere by burning fossil fuels since the start of the Industrial Revolution. To look at it another way, scientists estimate there is two and a half times more carbon locked away in the Arctic deep freezer than there is in the atmosphere today. Now, with a warming climate, that deep freezer is beginning to thaw and that long-frozen carbon is beginning to be released into the environment.
“The study we did was to look at what happens to that organic carbon when it is released,” Stubbins said. “Does it get converted to carbon dioxide or is it still going to be preserved in some other form?”
Stubbins and his colleagues conducted their fieldwork at Duvanni Yar in Siberia. There, the Kolyma River carves into a bank of permafrost, exposing the frozen organic material. This worked well for the scientists, as they were able to find streams that consisted of 100 percent thawed permafrost. The researchers measured the carbon concentration, how old the carbon was and what forms of carbon were present in the water. They bottled it with a sample of the local microbes. After two weeks, they measured the changes in the carbon concentration and composition and the amount of carbon dioxide that had been produced.
The study also confirmed what the scientists had suspected: The carbon being used by the bacteria is at least 20,000 years old. This is significant because it means that carbon has not been a part of the global carbon cycle in the recent past.
Lead author Robert Spencer of Florida State University added, “Interestingly, we also found that the unique composition of thawed permafrost carbon is what makes the material so attractive to microbes.”“We found that decomposition converted 60 percent of the carbon in the thawed permafrost to carbon dioxide in two weeks,” Stubbins said. “This shows the permafrost carbon is definitely in a form that can be used by the microbes.”
“If you cut down a tree and burn it, you are simply returning the carbon in that tree to the atmosphere where the tree originally got it,” Stubbins said. “However, this is carbon that has been locked away in a deep-freeze storage for a long time.
“This is carbon that has been out of the active, natural system for tens of thousands of years. To reintroduce it into the contemporary system will have an effect.”
The carbon release has the potential to create what scientists call a positive feedback loop. This means as more carbon is released into the atmosphere, it would amplify climate warming. That, in turn, would cause more permafrost to thaw and release more carbon, causing the cycle to continue.
“Currently, this is not a process that shows up in future (Intergovernmental Panel on Climate Change) climate projections; in fact, permafrost is not even accounted for,” Spencer said.
“Moving forward, we need to find out how consistent our findings are and to work with a broader range of scientists to better predict how fast this process will happen,” Stubbins said.
In addition to Stubbins and Spencer, the research team included Paul Mann from Northumbria University, United Kingdom; Thorsten Dittmar from the University of Oldenburg, Germany; Timothy Eglinton and Cameron McIntyre from the Geological Institute, Zurich, Switzerland; Max Holmes from Woods Hole Research Center; and Nikita Zimov from the Far-Eastern Branch of the Russian Academy of Science.
University of Georgia Skidaway Institute of Oceanography professor Marc Frischer will discuss his on-going research into black gill in shrimp in an Evening @ Skidaway program on March 12th. The program will be in the McGowan Library at the UGA Skidaway Institute, beginning with a reception at 6:30 p.m. to be followed by the lecture program at 7:15 p.m.
A Georgia shrimp with the Black Gill characteristics clearly visible.
In recent years, Georgia shrimpers have been very concerned about black gill, a mysterious condition affecting the coastal shrimp population. While the condition does not affect the edibility of the shrimp, many shrimpers believe that black gill may be largely responsible for reduced shrimp harvests. Frischer is leading a research project involving scientists, regulators and shrimpers from three states in an effort to determine the cause, effects and possible solutions to the black gill problem.
An “Evening @ Skidaway” is sponsored by the UGA Skidaway Institute of Oceanography and the Associates of Skidaway Institute.
The free program is open to the public.
For additional information, call 912-598-2325.
A sample of marine debris collected along the Georgia coast sits on a table at the UGA Skidaway Institute of Oceanography.
University of Georgia researchers are hoping to find a consistent way to record the marine debris—particularly pieces of plastic—crowding Georgia's beaches as part of an effort to find a solution for the growing problem.
Marine debris has been washing up on Georgia beaches and uninhabited islands for years. Combatting the issue starts with figuring out how big it is, and a new two-part study from the UGA Skidaway Institute of Oceanography and Marine Extension published online in the Marine Pollution Bulletin finds that marine debris reporting can improve if it becomes standardized.
The problem right now is this: A volunteer group goes out and records the weight or volume of the marine debris collected. However, volunteers don't often record the specific square feet measured or the contents of the debris. Due to a lack of report standardization, researchers often can't compare the marine debris, especially plastic fragments, reported by different groups.
"We've seen plastic usage go up dramatically," said study co-author Dodie Sanders, a marine educator and outreach coordinator for UGA Marine Extension, a unit of the Office of Public Service and Outreach. "It's an important 21st century global issue. We need to learn more to better understand the issues of marine debris."
The study's lead author Richard F. Lee, professor emeritus with the UGA Skidaway Institute of Oceanography, agrees.
"Plastic debris is created on land and then it goes into rivers, flows into the ocean and washes up on land," he said. "We've found that plastic debris ends up not only on populated beaches, but on inaccessible islands as well. We've found plastic everywhere on the coast."
The first part of the study gathered debris from 20 sites along Georgia's coast, including Tybee, Cumberland and Ossabaw islands. The debris was reported from volunteer organizations like Clean Coast, which hold monthly beach and marsh cleanups in Georgia.
"The volunteer groups reported the weight of the debris, though we didn't know the exact amount of plastic," Lee said. "Based off the volunteer information we received, we did a follow-up study to more precisely measure the marine debris in a fixed location and period of time."
The total collected debris ranged from 180 to 1,000 kilograms. The levels of plastic debris differed at each site over the course of the study, though plastic was consistently among the mix. Found plastic included plastic bottles, wrappers, food utensils and fragments of fishing gear.
Sanders spearheaded the second part of the study, where she and students collected plastic debris from Skidaway and Wassaw islands over a period of two years.
"While Dr. Lee did data analysis, I did some of the field work," Sanders said. "We picked the two islands in the second part of the study because they were accessible sites where Marine Extension often takes students for marine education."
For the fieldwork, Sanders and students visited the islands each month. They took inventory of what kinds of plastics were on specific areas of the coast.
"On about a monthly basis, I would take students to learn about debris and tally all the items on the islands," Sanders said. "We took areas of 200 meters by 40 meters and recorded the items found. We also used GPS units to mark what areas we had done."
The students, many of them in middle and high school, came from all over Georgia to assist. As part of Marine Extension, Sanders regularly teaches visiting students about marine life. When students volunteered to clean up, she tried to emphasize the issues surrounding debris.
"The bulk of the plastic comes from land," Sanders said. "When people think of marine debris, they think of the ocean. I try to emphasize watershed concepts—what happens upstream ultimately gets downstream."
"It can take years for plastic to degrade," Lee said, adding, "80 percent of the plastic found at Wassaw turned out to be fragments. The fragments then spread and can have a number of environmental effects."
Sanders says that since plastic debris is everywhere on the coast, it has to be addressed and reported efficiently to reduce its effects.
"There are proactive and reactive approaches to the issues of marine debris, and both are important," she said. "We've been reactive so far by picking up debris. The proactive approach is our role in educating the public and researching the negative impacts of marine debris."
The study was supported by the Georgia Department of Natural Resources Coastal Incentive Grant, NOAA Southeast Atlantic Marine Debris Initiative and the NOAA Marine Debris Program.
The full article on "The amount and accumulation rate of plastic debris on marshes and beaches on the Georgia coast" is available at www.sciencedirect.com/science/article/pii/S0025326X1400820
A research team from the University of Georgia Skidaway Institute of Oceanography has completed the first high-resolution, bathymetric (bottom-depth) survey of Wassaw Sound in Chatham County.
Led by Skidaway Institute scientist Clark Alexander, the team produced a detailed picture of the bottom of Wassaw Sound, the Wilmington River and other connected waterways. The yearlong project was developed in conjunction with the Georgia Department of Natural Resources.
The survey provides detailed information about the depth and character of the sound’s bottom. This information will be useful to boaters, but boating safety was not the primary aim of the project. The primary objective was to map bottom habitats for fisheries managers. DNR conducts fish surveys in Georgia sounds, but, according to Alexander, they have limited knowledge of what the bottom is like. “One of the products we developed is an extrapolated bottom character map,” Alexander said. “This describes what the bottom grain size is like throughout the sound. Is it coarse, or shelly or muddy? This is very important in terms of what kind of habitat there is for marine life.”
A second goal was to provide detailed bathymetric data to incorporate into computer models that predict storm surge flooding caused by hurricanes and other major storms. Agencies like the United States Army Corps of Engineers, the Federal Emergency Management Agency and the National Oceanographic and Atmospheric Administration use mathematical models to predict anticipated storm inundation and flooding for specific coastal areas. A key factor in an accurate modeling exercise is the bathymetry of the coastal waters.
“You need to know how the water will pile up, how it will be diverted and how it will be affected by the bottom morphology,” Alexander said. “Since we have a gently dipping coastal plain, storm inundation can reach far inland. It is important to get it as right as we can so the models will provide us with a better estimate of where storm inundation and flooding will occur.”
Funded by an $80,000 Coastal Incentive Grant from DNR, Alexander and his research team, consisting of Mike Robinson and Claudia Venherm, used a cutting-edge interferometric side-scan sonar system to collect bathymetry data. The sonar transmitter/receiver was attached to a pole and lowered into the water from Skidaway Institute’s 28-foot Research Vessel Jack Blanton. Unlike a conventional fishfinder, which uses a single pinger to measure depth under a boat, the Edgetech 4600 sonar array uses fan-shaped sonar beams to both determine water depth and bottom reflectivity, which identifies sediment type, rocky outcroppings and bedforms, in a swath across the boat’s direction of travel.
The actual process of surveying the sound involved long hours of slowly driving the boat back and forth on long parallel tracks. On each leg, the sonar produced a long, narrow strip indicating the depth and character of the sound bottom. Using high-resolution Global Positioning System data that pinpointed the boat’s exact location, the system assembled the digital strips of data into a complete picture of the survey area.
All the other sounds on the Georgia coast were mapped in 1933, but for some reason data from that time period for Wassaw Sound was unavailable. When the team began this project, they believed they were conducting the first survey of the sound. However, just as the researchers were finishing the project, NOAA released data from a 1994 single-beam survey that had been conducted in advance of the 1996 Olympic yachting races that were held in and near Wassaw Sound.
“This worked out very well for our project, because we are able to compare the differences between the two surveys conducted 20 years apart,” Alexander said. “We see areas that have accumulated sediment by more than 2 meters, and we also see areas that have eroded more than 2 meters since 1994. Channels have shifted and bars have grown or been destroyed.”
Because of advances in technology, the current survey is significantly richer in detail than the one conducted in 1994. “We can zoom down to a square 25 centimeters (less than a foot) on a side and know the bottom depth,” Alexander said.
The survey produced a number of findings that were surprising. The intersection of Turner Creek and the Wilmington River is a deep, busy waterway. Although most of the area is deep, the survey revealed several pinnacles sticking up 20 feet off the bottom. “They are round and somewhat flat, almost like underwater mesas,” Alexander said.
The researchers determined that the deepest place mapped in the study area was a very steep-sided hole, 23 meters deep, in the Half Moon River where it is joined by a smaller tidal creek. They also found several sunken barges and other vessels.
The survey data set is available to the public on the Georgia Coastal Hazards Portal at http://gchp.skio.usg.edu/. Alexander warns that while boaters should find the survey interesting, the information is intended for habitat research and storm surge modeling, not for navigation. “Because the bottom of Wassaw Sound is always shifting and changing, as our survey showed, don’t rely on the data for safe navigation,” he cautioned.
Alexander has already received a grant for an additional survey, this time of Ossabaw Sound, the next sound south of Wassaw Sound. He expects work to begin on that survey in early 2015.
The Skidaway Institute of Oceanography is a research unit of the University of Georgia located on Skidaway Island near Savannah. The mission of the institute is to provide the state of Georgia with a nationally and internationally recognized center of excellence in marine science through research and education.
Spencer, R. G. M., P. J. Mann, T. Dittmar, T. I. Eglinton, C. McIntyre, R. M. Holmes, N. Zimov, and A. Stubbins. 2015. Detecting the signature of permafrost thaw in Arctic rivers. Geophysical Research Letters (pagination pending), doi: 10.1002/2015GL063498
Bittar, T. B., A. A. H. Vieira, A. Stubbins, and K. Mopper. 2015. Competition between photochemical and biological degradation of dissolved organic matter from the cyanobacteria Microcystis aeruginosa. Limnology & Oceanography (pagination pending), doi: 10.1002/lno.10090
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