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 Listening in: Acoustic monitoring devices detect illegal hunting and logging
14.12.2017 | Gesellschaft für Ökologie e.V.

nachricht How fires are changing the tundra’s face
12.12.2017 | Gesellschaft für Ökologie 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: First-of-its-kind chemical oscillator offers new level of molecular control

DNA molecules that follow specific instructions could offer more precise molecular control of synthetic chemical systems, a discovery that opens the door for engineers to create molecular machines with new and complex behaviors.

Researchers have created chemical amplifiers and a chemical oscillator using a systematic method that has the potential to embed sophisticated circuit...

Im Focus: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

Engineers program tiny robots to move, think like insects

15.12.2017 | Power and Electrical Engineering

One in 5 materials chemistry papers may be wrong, study suggests

15.12.2017 | Materials Sciences

New antbird species discovered in Peru by LSU ornithologists

15.12.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>