Iceland volcano covered Europe with sulfur dioxide

B r arbunga outbreak produced more sulfur dioxide than all Europeans throughout the year

Breakout of Bardarbunga at Holuhraun in autumn 2014. © Peter Hartree / CC-by-sa 2.0
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Sulfur veils over Europe: The eruption of the Bárðarbunga on Iceland brought only a little ash, but more sulfur dioxide into the atmosphere. During its six-month eruption, the sulfur dioxide levels in the air rose across Europe, a European research team reports. Even in the Alps, the SO2 levels temporarily reached 50 times the normal levels. It could have been much worse.

When the glacier volcano Bárðarbunga erupted on 31 August 2014, it was not yet clear how long-lasting and thus extensive this eruption would become. For six months, the underground magma chamber spewed lava, gases and smoke. During this time, a total of 1.6 cubic kilometers of lava from columns in the Holuhraun field north of the glacier Vatnajökull swell and made the eruption the largest of Iceland in the last 200 years.

"This was the largest volcanic eruption in Iceland since the eruption of Laki some 200 years ago, " says first author Sigurdur Gislason of the University of Iceland. At the outbreak of the Laki 1883/84, 20 percent of the Icelandic population died and tens of thousands of people across Europe felt ash and sulfur emissions from the volcano. How much sulfur dioxide depleted the Bardarbunga and how far this distributed, Gislason and his colleagues have now investigated.

Sulfur dioxide throughout Europe

The result: Although the eruption of the Bárðarbunga was less explosive and only partially spectacular, it influenced all of Europe. The dreaded ash clouds, as at the Eyjafjallajökull outbreak in 2010, did not materialize, but a cloud of sulfur dioxide covered the continent. After all, almost twelve million tons of SO2 released the eruption over the course of the six months, as the researchers determined - that is more than the total anthropogenic SO2 emissions in Europe in 2011.

Frequency of sulfur dioxide concentrations above 350 micrograms per cubic meter in Iceland during the Bardarbunga eruption. Gslason et al. (2015) Geochem. Persp. Let.

In Iceland, the limit was exceeded for several days and sometimes even weeks, from which the SO2 pollution is considered to be harmful. This limit is 350 micrograms per cubic meter per hour in the EU. But even at 1, 200 meters altitude in the Austrian Alps, SO2 values ​​of 235 micrograms per cubic meter were measured. This corresponds to around 60 percent of the limit and is around 50 times higher than the concentration of sulfur dioxide normally used for this location. display

Happiness in misfortune

But it could have been a lot worse: "We were lucky with the timing and the weather, " Gislason explains. Favorable winds ensured that a large part of the volcanic emissions were blown to the north - over largely uninhabited regions of Iceland. In addition, the outbreak was in winter, so that the wind speeds are higher and the pollutants are thickened faster.

Also beneficial: In winter, less sulfur dioxide is converted into sulfuric acid and thus into acid rain. In addition, the eruption was in the rain shadow of the mighty Vatnaj kull Glacier. This, too, minimizes the proportion of gas converted into vats, as the researchers explain. "The position and timing of the Holuhraun eruption helped in many ways to minimize the impact of the outbreak on the environment and humans, " the researchers note.

Despite the relatively large amount of sulfur dioxide, the B Ausr arbunga outbreak therefore had little impact on the environment and human health. (Geochemical Perspectives Letters, 2015; doi: 10.7185 / geochemlet.1509)

(European Association of Geochemistry, 21.07.2015 - NPO)