End of August 2014 a fissure eruption has begun in the Holuhraun lava field which is located in the north-east of the Bardarbunga volcano system on Iceland. Since then this eruption exhibits a large and continuous flow of lava and a significant release of sulphur dioxide (SO2) into the lower troposphere. In contrast to the outbreak of the Eyjafjallajökull in Iceland in 2010 ash emissions, which caused a closure of air space over Europe for several days, are insignificant during the entire eruption episode of Bardarbunga. However, the high sulphur dioxide emissions of the current eruption pose a threat to the health of the inhabitants of Iceland. Measurements of the Icelandic Met Office (IMO) indicated emission rates of 20,000 – 50,000 tons of SO2 per day in September 2014. For comparison, the European Union daily emits about 14,000 tons of SO2 predominantly originated from energy production.

Depending on the weather situation, the volcanic SO2 emissions impact the air quality not only close to the unpeopled eruption site, but also other areas on Iceland, which are partly populated. For example, on September 9th 2014 high SO2 concentrations of nearly 4,000 micrograms per cubic meters were detected in the east Icelandic city of Reyðarfjörður, caused by prevailing westerly winds. Those observations indicate the highest SO2 values since the beginning of regular measurement records in 1970 in Iceland and they lie far above the European-wide defined one-hour critical value of 350 µg/m3. Again, this high SO2 concentration was even exceeded with measurements of 9,000 to 10,000 µg/m3 on October 26th 2014 in Höfn, also located in Eastern Iceland. The residents of the affected areas were recommended to remain indoors and to keep the windows and doors closed. Even outside of Iceland, especially in Norway increased sulphur dioxide measurements were quite frequent since the Bardarbunga has become active.

On September 22nd 2014 unusually high SO2 concentrations were also measured in some regions of Austria, at the German fringe of the alps, as well as in other parts of Central Europe. These high values agree with the forecasts of SO2 dispersion, daily conducted by the chemical transport model EURAD-IM at the Research Centre of Jülich and the Rhenish Institute of Environmental Research at the University of Cologne since the beginning of the eruption. Furthermore, the simulations indicate that the exceptionally high SO2 incidences are due to the transport of sulphur dioxide rich air from the Bardarbunga towards continental Europe.

According to an updated announcement of IMO, recently any detected SO2 value did not pass the health limit of 350 µg/m3. The assumed reduction in SO2 emissions is presumably a result of the general weakening of the seismic and volcanic activity of the Bardarbunga volcano system.

Text: Dr. Luise Fröhlich, Forschungszentrum Jülich (FZJ)/Rhenish Institute of Environmental Research at the University of Cologne (RIU).

For more information on the SO2 dispersion forecast as a result of the volcanic eruption close to Bardarbunga (Iceland).

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