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NEWS

The vast reservoir of carbon stored in Arctic permafrost is gradually being converted to carbon dioxide (CO2) after entering the freshwater system in a process thought to be controlled largely by microbial activity. However, a new study – funded by the National Science Foundation and published in the journal Science – concludes that sunlight and […]

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The vast reservoir of carbon stored in Arctic permafrost is gradually being converted to carbon dioxide (CO2) after entering the freshwater system in a process thought to be controlled largely by microbial activity.

However, a new study – funded by the National Science Foundation and published in the journal Science – concludes that sunlight and not bacteria is the key to triggering the production of CO2 from material released by Arctic soils.

The finding is particularly important, scientists say, because climate change could affect when and how permafrost is thawed, which begins the process of converting the organic carbon into CO2.
“Arctic permafrost contains about half of all the organic carbon trapped in soil on the entire Earth – and equals an amount twice of that in the atmosphere,” said Byron Crump, an Oregon State University microbial ecologist and co-author on the Science study. “This represents a major change in thinking about how the carbon cycle works in the Arctic.”

Converting soil carbon to carbon dioxide is a two-step process, notes Rose Cory, an assistant professor of earth and environmental sciences at the University of Michigan, and lead author on the study. First, the permafrost soil has to thaw and then bacteria must turn the carbon into greenhouse gases – carbon dioxide or methane. While much of this conversion process takes place in the soil, a large amount of carbon is washed out of the soils and into rivers and lakes, she said.
“It turns out, that in Arctic rivers and lakes, sunlight is faster than bacteria at turning organic carbon into CO2,” Cory said. “This new understanding is really critical because if we want to get the right answer about how the warming Arctic may feedback to influence the rest of the world, we have to understand the controls on carbon cycling.

“In other words, if we only consider what the bacteria are doing, we’ll get the wrong answer about how much CO2 may eventually be released from Arctic soils,” Cory added.

The research team measured the speed at which both bacteria and sunlight converted dissolved organic carbon into carbon dioxide in all types of rivers and lakes in the Alaskan Arctic, from glacial-fed rivers draining the Brooks Range to tannin-stained lakes on the coastal plain. Measuring these processes is important, the scientists noted, because bacteria types and activities are variable and the amount of sunlight that reaches the carbon sources can differ by body of water.

In virtually all of the freshwater systems they measured, however, sunlight was always faster than bacteria at converting the organic carbon into CO2.

“This is because most of the fresh water in the Arctic is shallow, meaning sunlight can reach the bottom of any river – and most lakes – so that no dissolved organic carbon is kept in the dark,” said Crump, an associate professor in Oregon State’s College of Earth, Ocean, and Atmospheric Sciences. “Also, there is little shading of rivers and lakes in the Arctic because there are no trees.”

Another factor limiting the microbial contribution is that bacteria grow more slowly in these cold, nutrient-rich waters.

“Light, therefore, can have a tremendous effect on organic matter,” University of Michigan’s Cory pointed out.

The source of all of this organic carbon is primarily tundra plants – and it has been building up for hundreds of thousands of years, but doesn’t completely break down immediately because of the Arctic’s cold temperatures. Once the plant material gets deep enough into the soil, the degradation stops and it becomes preserved, much like peat.

“The level of thawing only gets to be a foot deep or so, even in the summer,” Crump said. “Right now, the thaw begins not long before the summer solstice. If the seasons begin to shift with climate change – and the thaw begins earlier, exposing the organic carbon from permafrost to more sunlight – it could potentially trigger the release of more CO2.”\

The science community has not yet been able to accurately calculate how much organic carbon from the permafrost is being converted into CO2, and thus it will be difficult to monitor potential changes because of climate change, they acknowledge.

“We have to assume that as more material thaws and enters Arctic lakes and rivers, more will be converted to CO2,” Crump said. “The challenge is how to quantify that.”

Some of the data for the study was made available through the National Science Foundation’s Arctic Long-Term Ecological Research project, which has operated in the Arctic for nearly 30 years.
Other authors on the study are Collin Ward and George Kling of the University of Michigan.

The research was supported by the following National Science Foundation grants: NSF-OPP 1023270/1022876; NSF-PLR 1107593; and NSF DEB-1026843 and 1147378/1347042.

NEWS

Volcanoes can have multiple personalities, peaceful one minute, explosive the next. A geologist who has untangled these complicated states on land and at sea, improving our ability to see deadly eruptions coming, will receive the 2015 Vetlesen Prize. Stephen Sparks, a volcanologist at the University of Bristol, will be awarded a medal and $250,000 at […]

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Volcanoes can have multiple personalities, peaceful one minute, explosive the next. A geologist who has untangled these complicated states on land and at sea, improving our ability to see deadly eruptions coming, will receive the 2015 Vetlesen Prize. Stephen Sparks, a volcanologist at the University of Bristol, will be awarded a medal and $250,000 at a ceremony in New York in June. Considered the Nobel Prize of the earth sciences, theVetlesen Prize is supported by the G. Unger Vetlesen Foundation and administered by Lamont-Doherty Earth Observatory at Columbia University.
As a graduate student in the 1970s, Sparks became one of the first to apply math and physics to the interpretation of volcanic deposits in the field, bringing volcanology into the modern era. His methodical, collaborative approach has produced a long list of discoveries that have improved our practical understanding of volcanic hazards globally.
Born near London and raised in the city of Chester, Sparks developed an early interest in rocks exploring the caves and crags of the British countryside. He studied geology at Imperial College in London; an expedition that first summer mapping volcanic rocks in southern Iceland sealed his interest in volcanoes.

After finishing his PhD in 1974, Sparks worked with colleagues to model eruptive processes during stints at Lancaster University in Britain and the University of Rhode Island. In a 1977 study inNature, he showed how magma deep within the earth could mix with material closer to the surface to trigger an explosive eruption. Working with physicist Lionel Wilson, he explained how explosions sometimes shoot ash high into the stratosphere, but at other times unleash deadly flows of ash and gas down the flanks of volcanoes.  He went on to show in Icelandic volcanoes that the sideways flow of magma could cause the spectacular collapse of a caldera up to 40 miles away. Off the coast of Greece, his analysis of deep-sea volcanic rocks added support for the idea that the Thera eruption around 1500 BC may have influenced the fall of the ancient Minoans on the island of Crete.

 In 1978, Sparks moved to Cambridge University, where he published a series of influential papers with mathematician Herbert Huppert on the physics of magma chambers beneath volcanoes. In lab experiments, they demonstrated how heavy magma can become unstable and, counterintuitively, rise. In 1989, amid a restructuring of Britain’s research universities, Sparks and geochemist Bernie Wood were tapped to lead Bristol University’s geology department. There, in a country with no volcanoes of its own, they built one of the world’s leading centers for volcanology and the earth sciences.
When Montserrat’s Soufrière Hills volcano came to life in 1995, Sparks was picked to head monitoring efforts there and advise the government. Ongoing research has led to a better understanding of pyroclastic flows–rapid exhalations of gas, ash and rock dished out by explosive volcanoes like Soufrière Hills and its neighbor, Mount Pelée on Martinique, whose 1902 eruption killed 30,000 people. Drawing on data from Soufrière Hills, Sparks helped to show in a 1999 study inNature how small pressure variations in a volcano’s magma chamber, or in the stickiness of its magma, can create wild mood swings, turning a gently oozing eruption into something explosive. He also pioneered methods for assessing the danger posed by active volcanic eruptions, helping governments to improve decisions about evacuations and rebuilding. Thanks in part to Sparks’s work, the eruptions on Montserrat are now taught in British schools.
More recently, in a 2006 study in the Journal of Petrology, Sparks helped model the evolution of earth’s crust in deep “hot zones” where chemically altered magmas drive volcanism. He has partnered with the mining company BHP Billiton in Chile and DeBeers in South Africa to learn more about the volcanic processes that produce copper and diamond deposits. He has also assessed the safety of old volcanic rocks in Britain, Japan and the United States for storing radioactive waste. He has coordinated a global assessment of volcanic risk for the United Nations.
Elected to the Royal Society at the early age of 38, he is among the top-cited volcanologists ever. An enthusiasm to share his knowledge has led to frequent appearances on TV and in print. Colleagues remark on his collegiality. “Everyone has an egotism that drives their research, but Steve never lets it get in the way of working with others,” said Barry Voight, a volcanologist at Penn State. “You know he’s not going to pick your brain and run off with your ideas. Instead, he will often improve on them.”
Sparks lives in Bristol with his wife, Ann Talbot Sparks, an elementary school teacher; they have two grown sons. His previous awards include the Geological Society of London’s Wollaston Medal in 2011, the European Geosciences Union’s Arthur Holmes Medal in 2004 and the Geological Society of America’s Arthur Day Medal in 2000.
Since the Vetlesen Prize was first awarded in 1959, recipients have included geologist J. Tuzo Wilson, a key force in developing the theory of plate tectonics; oceanographer Walter Munk, whose work has shaped our understanding of tides, waves, and ocean mixing; astronomer Jan Oort, who elucidated the architecture of galaxies and the outer solar system; geochemist Wallace Broecker, a father of modern climate science; and geologist Walter Alvarez, who connected the extinction of the dinosaurs to an asteroid impact.