Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Fires fuel mercury emissions

11.01.2007
Forest fires release more mercury into the atmosphere than previously recognized, a multidisciplinary research project at the University of Michigan suggests.

The study, which has implications for forest management and global mercury pollution, was published online today (Jan. 9) in the journal Global Biogeochemical Cycles.

Doctoral student Abir Biswas, the paper's lead author, came up with the idea for the project when he was a student at U-M's Camp Davis Rocky Mountain Field Station near Jackson Hole, Wyoming. Wildfires were burning all around the station that summer, and smoke blanketed the camp. Around that time, Biswas happened to read a new scientific paper suggesting the possible role of fires in global mercury emissions.

"There I was, watching forest fires around our field camp, and it seemed like the ideal place to study the problem," he said.

The study Biswas read investigated mercury emissions from the combustion of foliage at locations around the USA and extrapolated to estimate mercury release during forest fires. "I'm interested in earth surface geochemistry so I wanted to approach the question differently," Biswas said.

Over the next two summers, under the direction of U-M professor Joel Blum, Biswas collected core samples of forest soil from burned and unburned areas, using sections of PVC pipe sharpened at one end to obtain the cylindrical samples. He and Blum also collaborated with U-M professor Gerald Keeler and former research scientist Bjorn Klaue to take air samples at Camp Davis—measuring mercury and trace metals over two summers—which provided the scientists with a picture of the atmospheric background on which the fires were superimposed.

Forests act as mercury traps because mercury in the atmosphere—which comes from both natural and human-generated sources such as coal-fired power plants and municipal waste incinerators—collects on foliage. When the foliage dies, it falls to the forest floor and decomposes, and the mercury enters the soil. Because it binds strongly to organic molecules, mercury is most prevalent in the top several inches of soil, where organic matter is concentrated. By comparing the mercury content of burned soil with that of unburned soil, the researchers could estimate how much mercury was released when forests burned.

They found that both the type of trees in the forest and the severity of the fire affected the amount of mercury released. The type of tree makes a difference because evergreens take up more mercury from the atmosphere on their needles than do broad-leafed trees, leading to more mercury accumulation in the soil prior to the fire.

Based on their analysis and estimates of the area of forest and shrub land burned annually in the United States, Biswas, Blum and coworkers calculated that wildfires and prescribed burns account for approximately 25 percent of human-generated mercury emissions in this country.

Understanding the role fires play in mercury emissions is particularly important in light of predictions that forest fires will increase as global warming makes some parts of the world hotter and drier, said Blum, who is the John D. MacArthur Professor of Geological Sciences and director of Camp Davis.

The findings also have implications for forest fire management, Biswas said. "When you let fires run free in an area where they have been suppressed for a long time, as happened in the Yellowstone fire of 1988, the fires end up burning a huge area that has been accumulating mercury for a long time, so a lot of mercury is released. By contrast, when you allow fires to occur in natural 50- to 100-year cycles, you end up with more frequent, less severe fires, which release less of the mercury in the soil. So the current shift in management practices from suppressing fires to letting some of them burn suggests that in the immediate future there may be a lot of high mercury release fires, but that down the road the amount of mercury released from these fires should drop."

In a related project, the researchers are trying to identify the sources of the atmospheric mercury that ended up in the forests they studied. Preliminary results suggest that much of it came from mining operations in the western United States.

Studies of the sources and fate of mercury pollution are critical, Blum said, because it's a problem that won't go away. "Once mercury starts getting emitted and deposited into a forest, it then gets re-emitted and re-deposited and re-emitted again. So the legacy of mercury pollution will be with us for a very long time."

Funding was provided by grants from the National Institute of Environmental Health Sciences to Blum and from the department of Geological Sciences to Biswas.

Nancy Ross-Flanigan | EurekAlert!
Further information:
http://www.umich.edu

More articles from Ecology, The Environment and Conservation:

nachricht Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF

nachricht Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Future electronic components to be printed like newspapers

A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.

The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

A smart safe rechargeable zinc ion battery based on sol-gel transition electrolytes

20.07.2018 | Power and Electrical Engineering

Reversing cause and effect is no trouble for quantum computers

20.07.2018 | Information Technology

Princeton-UPenn research team finds physics treasure hidden in a wallpaper pattern

20.07.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>