Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists Estimate Mercury Emissions from U.S. Fires

19.10.2007
West Coast and Southeastern States are Major Emitters

Forest fires and other blazes in the United States likely release about 30 percent as much mercury as the nation's industrial sources, according to initial estimates in a new study by scientists at the National Center for Atmospheric Research (NCAR). Fires in Alaska, California, Oregon, Louisiana, and Florida emit particularly large quantities of the toxic metal, and the Southeast emits more than any other region, according to the research. The mercury released by forest fires originally comes from industrial and natural sources.

The study, "Mercury Emission Estimates from Fires: An Initial Inventory for the United States," is being published online today by the journal Environmental Science and Technology. The research was funded by the National Science Foundation, NCAR's principal sponsor, as well as by the Electric Power Research Institute and the Environmental Protection Agency.

The paper estimates that fires in the continental United States and Alaska release about 44 metric tons of mercury into the atmosphere every year. It is the first study to estimate mercury emissions for each state, based on a new computer model developed at NCAR. The authors caution that their estimates for the nation and for each state are preliminary and are subject to a 50 percent or greater margin of error. A metric ton is about 10% larger than a U.S. ton.

Mercury does not originate in fires. Instead, it comes from industrial and natural sources, often settling into soil and plant matter. Intense fires then release the mercury back into the atmosphere, where it poses a new danger because it can reach sensitive waterways and other areas.

"What we are seeing is that mercury from other sources is being deposited into the vegetation and soil and then being released back into the atmosphere, where it can travel far downwind and contaminate watersheds and fragile ecosystems," says NCAR scientist Christine Wiedinmyer, one of the study's co-authors. "It's important for federal and state officials to have this type of information and to know where mercury is coming from so they can better protect public health and the environment."

Mercury is a toxin that can threaten human health and ecosystems. Depending on its form, it can travel long distances in the atmosphere before returning to Earth through precipitation or dry deposition. It is particularly dangerous if it winds up in waterways, because it can transform into methylmercury and move up the aquatic food chain while becoming increasingly concentrated. The Environmental Protection Agency warns pregnant women and young children against consuming some types of fish and shellfish because of mercury levels.

To estimate the emissions, Wiedinmyer and NCAR scientist Hans Friedli, who co-authored the article, used satellite observations of fires, aircraft and ground-based measurements of mercury, and a new computer model of fire emissions that Wiedinmyer created. They focused on a five-year period from 2002 to 2006 and examined every state except Hawaii, for which they lacked detailed data.

The paper warns that its estimates are subject to at least a 50 percent margin of error due to imprecise information about both the exact size of fires and the amount of mercury emitted by each fire. The estimates for the nation and each state are midpoints; Alaska's emissions, for example, are likely to be from 6.3 to 18.8 tons, but 12.5 is the midpoint.

"These are initial estimates, but they clearly point to fires in certain states emitting particularly high amounts of mercury," Wiedinmyer says.

High and low emitters

Alaska, which experienced vast wildfires from 2002 to 2006, released far more mercury than other states, with California releasing the most in the continental United States. Alaska's annual emissions over the five-year period were estimated at about 12.5 metric tons. California averaged 3.4 tons, followed by Oregon (2.5 tons), Louisiana (1.95) and Florida (1.89).

The authors also quantified emissions by regions, as defined by the National Interagency Fire Center. The Southeast, a region that encompasses 13 states and includes border states such as Kentucky and Oklahoma, emitted 14.4 tons per year--the most of any of the NIFC regions. In addition to Louisiana and Florida, three other Southern states ranked in the top ten: Georgia, Texas, and Alabama.

In contrast, states in the Midwest and Great Lakes emitted comparatively little mercury from fires. However, they could potentially be affected by emissions from western wildfires.

The emissions varied widely by season and year, depending on the extent of fires and prescribed burns. Western states in general had far higher emissions in the summer and early fall, when wildfires are more prevalent. In the Southeast, however, emissions typically peaked in the spring and fall, which may reflect prescribed burning practices in the region.

The annual average of 44 tons for fires in the United States and Alaska compares to a total of about 108 tons that is released each year from industrial sources, such as power plants, incinerators, boilers, and mines. Mercury also comes from natural sources, including volcanoes and ocean vents.

Downwind impacts?

One of the next steps for the researchers will be to examine how much mercury from fires is deposited on nearby downwind areas, compared to how much travels around the hemisphere. Most of the mercury in fire emissions is in gaseous form, traveling thousands of miles before coming down in small amounts in rain or snow. But about 15 percent of the mercury is associated with airborne particles, such as soot, some of which may fall to Earth near the fire.

"We would like to determine the risk of mercury exposure for residents who live downwind of large-scale fires," Friedli says.

The University Corporation for Atmospheric Research manages the National Center for Atmospheric Research under primary sponsorship by the National Science Foundation (NSF). Opinions, findings, conclusions, or recommendations expressed in this document are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

David Hosansky | EurekAlert!
Further information:
http://www.ucar.edu/news/releases/2007/mercury.shtml
http://www.ucar.edu

More articles from Ecology, The Environment and Conservation:

nachricht Preservation of floodplains is flood protection
27.09.2017 | Technische Universität München

nachricht Conservationists are sounding the alarm: parrots much more threatened than assumed
15.09.2017 | Justus-Liebig-Universität Gießen

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: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

NRL clarifies valley polarization for electronic and optoelectronic technologies

20.10.2017 | Interdisciplinary Research

Metallic nanoparticles will help to determine the percentage of volatile compounds

20.10.2017 | Materials Sciences

Shallow soils promote savannas in South America

20.10.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>