Researchers at Michigan State University, the U.S. Geological Survey, the National Center for Atmospheric Research, and the Canadian Forest Service find that wildfires, which are becoming more frequent and intense, are unleashing this sequestered mercury at levels up to 15 times greater than previously calculated. Their report was published 19 August in Geophysical Research Letters.
"This study makes the point that while peat lands are typically viewed as very wet and stagnant places, they do burn in continental regions, especially late in the season when water tables are depressed," said Merritt Turetsky, lead author of the study. "When peat lands burn, they can release a huge amount of mercury that overwhelms regional atmospheric emissions. Our study is new in that it looks to the soil record to tell us what happens when peat soil burns, soil that has been like a sponge for mercury for a long time."
Normal atmospheric conditions naturally carry the mercury emitted from burning fossil fuel and other industry northward, where it eventually settles on land or water surfaces. The cold, wet soils of the boreal forest region in Alaska and northern Canada have been efficient in retaining, or sequestering, mercury.
"When we walk across the surface of a peat land, we are standing on many thousands of years of peat accumulation," Turetsky said. "This type of wetland is actually doing us a service. Peat lands have been storing mercury from the atmosphere since well before and during the Industrial Revolution, locking it in peat where it's not causing any biological harm, away from the food web."
In addition to industrial activity, climate change also appears to be disrupting the mercury cycle. Increasingly, northern wetlands are drying out. Forest fires are burning more frequently, more intensely, and later in the season, which Turetsky believes will make peat lands more vulnerable to fire. In May, Turetsky co-authored with Eric Kasischke of the University of Maryland another Geophysical Research Letters paper that documented recent changes in North American fires and proposed that more frequent summer droughts and severe fire weather have increased burn areas.
"We are suggesting that environmental mercury is just like a thermometer. Levels will rise in the atmosphere with climate change, but due to increasing fire activity in the north and not solely due to warming, said Jennifer Harden, soil scientist at the U.S. Geological Survey and a co-author of the study.
In the newly published paper, Turetsky and her co-authors measured the amount of mercury stored in soils and vegetation of forests and peat lands, then used historical burn areas and emission models to estimate how much of that mercury is released to the atmosphere at a regional scale during fires.
The group studied more than five years of prescribed burns and natural fires to measure the influence of burning on terrestrial mercury storage. They also sampled smoke plumes to measure atmospheric mercury levels as fires blaze.
Their findings indicate that drier conditions in northern regions will cause soil to relinquish its hold on hundreds of years of mercury accumulation, sending that mercury back into the air at levels considerably higher than previously realized.
We're talking about mercury that has been relatively harmless, trapped in peat for hundreds of years, rapidly being spewed back into the air," Turetsky said. "Some of it will fall back onto soils. Some will fall into lakes and streams where it could become toxic in food chains. Our findings show us that climate change is complex and will contribute to the pollution of food chains that are very far away from us, in remote regions of the north."
The research was funded by the U.S. Geological Survey, the National Center of Atmospheric Research (supported by the National Science Foundation), and the Electric Power Research Institute. Turetsky's work also is supported by Michigan State University's Michigan Agricultural Research Station.
Harvey Leifert | AGU
Predicting unpredictability: Information theory offers new way to read ice cores
07.12.2016 | Santa Fe Institute
Sea ice hit record lows in November
07.12.2016 | University of Colorado at Boulder
Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.
Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
09.12.2016 | Life Sciences
09.12.2016 | Ecology, The Environment and Conservation
09.12.2016 | Health and Medicine