Volcanic ‘plumerang’ or boomerang-like return of a volcanic plume with potential health-risk in Iceland

VolcanoesIceland.png
a) Location map of the Holuhraun eruption site (lava flow extent in red) and the two populated areas: Reykjavik, city capital area, and Reykjahlio. b) Holuhraun eruption during the January 2015 field campaign – activity exclusively effusive lava flow width ~ 50 m (Source: Ilyinska et al., 2017)

All volcanoes are on satellite watch due to their continuous gas emissions, in particular SO2 – Sulphur dioxide, and their impacts after eruptions on air quality and landslide risks. A new study, from University of Leeds (Ilyinska et al., 2017), has found a previously undetected potential health risk from the high concentration of small particles – aerosols – found in a boomerang-like return of a volcanic plume.

This study focused on 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.

The 2014–2015 Holuhraun eruption in Iceland, emitted ∼11 Tg of SO2 into the troposphere over 6 months, and caused one of the most intense and widespread volcanogenic air pollution events in centuries, exceeding hourly air quality standards (350 μg/m3) for SO2 on 88 occasions in Reykjahlíð town (100 km distance), and 34 occasions in Reykjavík capital area (250 km distance). Average daily concentration of volcanogenic sulphate particles exceeded 5μg/m3 on 30 days in Reykjavík capital area.

2 types of plume impacted the downwind populated areas:

  • The first type was characterised by high concentrations of both SO2 gas and fine particles,
  • The second type had a low SO2 gas concentration.

Ilyinska et al. (2017) suggest that this second type was a mature plume where sulphur had undergone significant gas-to-aerosol conversion in the atmosphere. This second plume had circled back to Icelandic cities and towns long after the health warning about the initial plume had been lifted. The return of this second mature plume, named as a ‘plumerang’, meant that the sulphur dioxide (SO2) levels were reduced and within the European Commission air quality standards and, therefore, there were no health advisory messages in place.

SO2_aer.png
Dispersion model of hourly-mean SO2 (left) and sulphate aerosol (SO42−, right) surface mass concentrations (μg/m3) in September 2014. Panels (a) and (b) show a mature low Sgas/SAerosolplume reaching the Reykjavik capital area on 14 and 20 September 2014 (right), whereas SO2 mass concentrations are very low in the same location on those days (left). Panel (c) shows a ‘near-miss’ situation with a highly sulphate-rich mature plume narrowly passing the densely populated south-east coast of Iceland on 8 September 2014.

However, both types of plume were rich in fine aerosol, sulphate (on average ∼90% of the aerosol mass) and various trace species, including heavy metals. The fine size of the volcanic aerosol mass (~75–80%), combined with chemical components, have potential adverse implications for environmental and health impacts (e.g. exacerbating asthma attacks). 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. But, only the dispersion of volcanic SO2 gas was forecast in public warnings and operationally monitored during the eruption.

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’.” (said lead author, Dr Ilyinskaya from the Institute of Geophysics and Tectonics at Leeds). “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.”

For the future, Ilyinska et al. (2017) strongly 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.

The gas-to-particle conversion is quite typical for some so-called trace gases that are also precursor of aerosol particles, such as NO2 – Nitrogen dioxide, and SO2.

 

More information on:

  • WebPage on aerosol particles here
  • Previous WebPost on “Volcanoes on Sentinel-2 and OMI satellites watch – First global emission maps!” here
  • Ilyinska et al. (2017): Evgenia Ilyinskaya, Anja Schmidt, Tamsin A. Mather, Francis D. Pope, Claire Witham, Peter Baxter, Thorsteinn Jóhannsson, Melissa Pfeffer, Sara Barsotti, Ajit Singh, Paul Sanderson, Baldur Bergsson, Brendan McCormick Kilbride, Amy Donovan, Nial Peters, Clive Oppenheimer, Marie Edmonds. Understanding the environmental impacts of large fissure eruptions: Aerosol and gas emissions from the 2014–2015 Holuhraun eruption (Iceland). Earth and Planetary Science Letters, 2017; DOI: 10.1016/j.epsl.2017.05.025 here
  • “Volcanic ‘plumerang’ could impact human health” on geology page here

 

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