---

Volcanic gases could deplete ozone layer

June 13, 2012

SELFOSS, ICELAND-Giant volcanic eruptions in Nicaragua over the past 70,000 years could have injected enough gases into the atmosphere to temporarily thin the ozone layer, according to new research. And, if it happened today, a similar explosive eruption could do the same, releasing more than twice the amount of ozone-depleting halogen gases currently in stratosphere due to manmade emissions.

Bromine and chlorine are gases that "love to react - especially with ozone," said Kirstin Krüger, a meteorologist with GEOMAR in Kiel, Germany. "If they reach the upper levels of the atmosphere, they have a high potential of depleting the ozone layer."

New research by Krüger and her colleagues, which she presented today at a scientific conference in Selfoss, Iceland, combined a mixture of field work, geochemistry and existing atmospheric models to look at the previous Nicaraguan eruptions. And the scientists found that the eruptions were explosive enough to reach the stratosphere, and spewed out enough bromine and chlorine in those eruptions, to have an effect on the protective ozone layer. Krüger's talk was at the American Geophysical Union's Chapman Conference on Volcanism and the Atmosphere.

Steffen Kutterolf, a chemical volcanologist with GEOMAR and one of Krüger's colleagues, tackled the question of how much gas was released during the eruptions. He analyzed gases that were trapped by minerals crystallizing in the magma chambers, and applied a novel method that involves using the high-energy radiation from the German Electron Synchrotron in Hamburg to detect trace elements, including bromine. From that, Kutterolf estimated the amount of gas within magma before the eruptions, as well as the gas content in the lava rocks post-eruption. The difference, combined with existing field data about the size of the eruption, allowed the scientists to calculate how much bromine and chlorine are released.

Previous studies have estimated that in large, explosive eruptions - the type that sends mushroom clouds of ash kilometers high - up to 25 percent of the halogens ejected can make it to the stratosphere. For this study, the research team used a more conservative estimate of 10 percent reaching the stratosphere, to calculate the potential ozone layer depletion.

Taking an average from 14 Nicaraguan eruptions, the scientists found bromine and chlorine concentrations in the stratosphere jumped to levels that are equivalent to 200 percent to 300 percent of the 2011 concentrations of those gases. The Upper Apoyo eruption 24,500 years ago, for example, released 120 megatons of chlorine and 600 kilotons of bromine into the stratosphere.

Volcanic sulfate aerosols alone can lead to an ozone increase - if chlorine levels are at low, pre-industrial levels, Krüger said. But bromine and chlorine are halogens, gases whose atoms have seven electrons in the outer ring. To reach a stable, eight-electron configuration, these atoms will rip electrons off of passing molecules, like ozone. So when an eruption also pumps bromine and chlorine levels into the stratosphere, the ozone-depleting properties of the gases together with aerosols is expected to thin the protective layer.

"As we have bromine and chlorine together, we believe that this can lead to substantial depletion," she said. "And this is from one single eruption."

Because the effects are in the stratosphere, where the volcanic gases can be carried across the globe, eruptions of tropical volcanoes could lead to ozone depletion over a large area, Krüger said, potentially even impacting the ozone over polar regions. However, that's a question for future research to address. Some volcanic gases can last in the stratosphere up to six years, she added, although the most significant impacts from eruptions like Mount Pinatubo were within the first two years.

The next step in the research, Krüger said, is to investigate how much damage to the ozone layer the volcanic gases caused in the past - and what the damage could be from future volcanic eruptions in the active Central American region.

American Geophysical Union

Related Volcanic Gases Current Events and Volcanic Gases News Articles

Volcanic aerosols, not pollutants, tamped down recent Earth warming, says CU-Boulder study
A team led by the University of Colorado Boulder looking for clues about why Earth did not warm as much as scientists expected between 2000 and 2010 now thinks the culprits are hiding in plain sight -- dozens of volcanoes spewing sulfur dioxide.

Ups and downs of biodiversity after mass extinction
The climate after the largest mass extinction so far 252 million years ago was cool, later very warm and then cool again.

EARTH: Danger in paradise -- the hidden hazards of volcano geotourism
Beautiful views and exotic thrills draw millions of tourists to volcanic sites each year. Previously frequented by smaller numbers of experienced hikers and trained tour guides, today's volcanic sites are plagued by throngs of novice hikers, who are often ill-prepared and uneducated about the risks of volcano geotourism.

Avalanche of reactions at the origin of life
Volcanic-hydrothermal flow channels offer a chemically unique environment, which at first glance appears hostile to life. It is defined by cracks in the crust of the earth, through which water flows, laden with volcanic gases are contacting a diversity of minerals.

Could Siberian volcanism have caused the Earth's largest extinction event?
Around 250 million years ago, at the end of the Permian geologic period, there was a mass extinction so severe that it remains the most traumatic known species die-off in Earth's history.

Siberian hot springs reveal ancient ecology
Exotic bacteria that do not rely on oxygen may have played an important role in determining the composition of Earth's early atmosphere, according to a theory that UChicago researcher Albert Colman is testing in the scalding hot springs of a volcanic crater in Siberia.

Technology in the extreme
Radio transmitters that can withstand temperatures of up to 900 oC could soon be dropped into the depths of the earth to provide early warning of a volcanic eruption.

Can We Spot Volcanoes on Alien Worlds? Astronomers Say Yes.
Volcanoes display the awesome power of Nature like few other events. Earlier this year, ash from an Icelandic volcano disrupted air travel throughout much of northern Europe. Yet this recent eruption pales next to the fury of Jupiter's moon Io, the most volcanic body in our solar system.

Volcanic eruptions in North America were more explosive in ancient past
Millions of years ago, volcanic eruptions in North America were more explosive and may have significantly affected the environment and the global climate. So scientists report in this week's issue of the journal Nature.

Volcanic eruption in Iceland unlikely to have global effects, says CU-Boulder scientist
The eruption of an Icelandic volcano that sent a huge plume of ash into the atmosphere and caused sweeping disruptions of air traffic over Great Britain and Scandinavia today will likely dissipate in the next several days, according to a University of Colorado at Boulder atmospheric scientist.

---

More Volcanic Gases Current Events and Volcanic Gases News Articles

---