A new study has found a previously undetected potential health risk from the high concentration of small particles found in a boomerang-like return of a volcanic plume.
A team of scientists, led by Dr Evgenia Ilyinskaya at the University of Leeds, traced the evolution of the plume chemistry from the 2014-2015 Icelandic Holuhraun lava field eruption and found a second type of plume that impacts air quality.
This second plume had circled back to Icelandic cities and towns long after the health warning about the initial plume had been lifted.
Lead author, Dr Ilyinskaya from the Institute of Geophysics and Tectonics at Leeds, said: "The return of this second, mature, plume, which we referred to as a 'plumerang', showed that the volcanic sulphur had undergone a gas-to-particle conversion by spending time in the atmosphere. This conversion meant that the sulphur dioxide (SO2) levels of the plumerang were reduced and within the European Commission air quality standards and therefore there were no health advisory messages in place.
"However, our samples showed that the mature plume was instead very rich in fine particles which contained high concentrations of sulphuric acid and trace metals. The concentrations of these trace metals did not reduce as the plume matured and included heavy metals found in human-made air pollution that are linked to negative health effects.
"On at least 18 days during the 6-month long eruption the plumerang was in the capital city of Reykjavík, while the official forecast showed 'no plume'."
The fine particles found in the plumerang are so small they can penetrate deep into the lungs, potentially causing serious health problems such as exacerbating asthma attacks.
It is estimated that short and long-term exposure to this type of fine particles, from both human-made and natural sources, cause over three million premature deaths globally per year and remains the single largest environmental health risk in Europe.
Dr Ilyinskaya is currently researching the possible health impacts of the plumerang in collaboration with the University of Iceland. However there is already anecdotal evidence suggesting adverse effects.
Dr Ilyinskaya said: "We spoke to people living in Reykjavik who described a burning sensation in the throat and eyes when the SO2 levels would have been well within air quality standards but the particle-rich plumerang would have been over the city."
During the six-month-long eruption, the Icelandic Meteorological Office's daily forecasts of the plume dispersion accounted only for SO2 concentrations in the young plume. The mature plume was not forecast as part of volcanic air pollution monitoring.
The study, published in Earth and Planetary Science Letters, recommends that in future gas-rich eruptions both the young and mature plumes should be considered when forecasting air pollution and the dispersion and transport pattern of the plume.
Co-author Dr Anja Schmidt, from the Institute of Climate and Atmospheric Science as Leeds, said: "The Holuhraun eruption caused one of the most intense and widespread volcanogenic air pollution events in centuries. It's estimated that the amount of sulphur dioxide released into the atmosphere was roughly two times that of a yearly total of SO2 emissions generated by the European Economic area.
"It gave us a rare opportunity to study volcanism of this style and scale using modern scientific techniques. The data we have gathered will be invaluable to preparing for a potential future event and its impacts on air quality and human health."
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Anja Schmidt, University of Leeds
Evgenia Ilyinskaya, University of Leeds
Morten S. Riishuus, University of Iceland
Mike Burton, University of Manchester
Dr Evgenia Ilyinskaya and Dr Anja Schmidt are available for interview. Please contact press officer Anna Martinez at +44 (0)113 34 34196 email@example.com for further information.
Notes to editors:
- Icelandic large fissure eruptions were included in the UK National Risk Register in 2012 as one of the highest priority risks, due to the significant consequences caused by the Laki eruption 1783-1784. During the Laki eruption, a thick sulphate aerosol veil and fluoride contamination of pasture and drinking water for livestock, led to the loss of nearly 20% of Iceland's population through famine. It has also been suggested that mortality in the UK and mainland Europe increased due to this eruption. Holuhraun eruption 2014-2015 was the first modern opportunity to study a large Icelandic fissure eruption.
- Ilyinskaya et al. traced the evolution of the plume chemistry from the eruption site to two key areas of population: Reykjahlíð, which is the nearest municipality to Holuhraun (100 km distance) and Reykjavík capital area, which hosts roughly 60% of Iceland's population (250 km distance)
- Filter packs were used to collect simultaneous samples of gas and aerosol particle matter at three sites: the eruption site, Reykjahlíð and the Reykjavík capital area. Cascade impactors were used for size-segregated sampling of the particle matter.
- Gaseous SO2 concentration is routinely monitored around Iceland by the Environment Agency of Iceland air quality stations. Automated SO2 stations both in Reykjahlíð and Reykjavík were in operation before the onset of the eruption.
Understanding the environmental impacts of large fissure eruptions: Aerosol and gas emissions from the 2014-2015 Holuhraun eruption (Iceland) will be published in Earth and Planetary Science Letters 09 June 2017 (DOI: 10.1016/j.epsl.2017.05.025)
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Additional authors from:
University of Oxford, University of Birmingham, Met Office, University of Cambridge, King's College London, Environment Agency of Iceland, Icelandic Meteorological Office
This work was funded by the NERC urgency grant NE/M021130/1 'Source and longevity of sulphur in Icelandic flood basalt eruption plumes'.
The research has also benefited from the funding of the European Research Council under the European Union's Seventh Framework Programme (FP/2007-2013)/ERC grant agreement no. ; European Community's Seventh Framework Programme Grant No. 308377 (Project FUTUREVOLC) and support from the NERC-funded Centre for Observation and Modelling of Earthquakes, Volcanoes and Tectonics (COMET).