Iceland's volcanic eruption stokes toxic
gas fears
The
Holuhraun eruption is emitting high volumes of toxic gases and raising health
and environmental concerns.
Eruption
of Holuhraun volcano in Iceland [Birkefeldt Moller Pedersen/Al Jazeera]
Reykjavik,
Iceland - For the past five months, Icelandic weather
forecasts have included daily updates on
the movement of noxious gas plumes emitted by the ongoing Holuhraun volcanic
eruption.
Poisonous gas appeared in late
August last year soon after Holuhraun began to spew molten rock. "Most of
the gas is sulphur dioxide, water and carbon dioxide," said Thorolfur
Gudnason, a medical professional with Iceland's Directorate of Health.
"The other gases occur in much lower quantities."
Sulphur dioxide, which causes respiratory, eye and throat problems, is responsible
for most of the eruption-related health issues, said Gudnason.
"But carbon dioxide can be
dangerous to those who work near the volcano itself," he said, referring
to scientists studying the lava field.
The 85sq km lava field is the
size of Manhattan and located far from inhabited areas in a remote central part
of Iceland, just north of the Vatnajokull glacier in an area known as
Holuhraun, from which the volcano gets its name.
Unlike the smaller, 2010
Eyjafjallajokull eruption, which spouted ash and disrupted air traffic across
Europe, Holuhraun doesn't spew ash - this only happens when the eruption occurs
beneath a glacier.
But the gas emitted is the most
dangerous the country has experienced in more than 200 years.
"We have not seen such
levels of gas in Iceland in recent times, not since the Laki eruption in
1783," said Evgenia Ilyinskaya, a volcanologist with the British
Geological Survey studying the Holuhraun emissions.
The devastating eruption of Laki started in June 1783
and lasted until February 1784 - wiping out a fifth of Iceland's population.
This eruption is a
first in many ways, said Ilyinskaya. "Normally eruptions don't last so
long," and it's the largest and only European basalt flood eruption since Laki.
Monitoring toxic gases
With volcanic gas emissions at such high levels, Icelandic
authorities have installed 27 automatic monitors around the country that measure
sulphur dioxide along with portable meters, some of which are attached to
police vehicles.
Depending on wind conditions, sulphur fumes can get blown
around and the entire country, sometimes exceeding 2,000 µg/m3 at different points throughout a day.
The Environment Agency set 350 µg/m3 for a
one-hour period and 125 µg/m3 for a 24-hour period as
acceptable exposure limits to sulphur dioxide. When the concentration rises,
advisories are posted online, via Facebook and by SMS, and Icelanders are advised to avoid going
outdoors and engaging in physical activity.
Levels more than 600µg/m3 are considered dangerous
for people who have existing health conditions and are more likely to
experience respiratory problems. At these levels, such people are advised to
stay indoors with the windows closed.
Meteorologist
Einar Sveinbjornsson is concerned about the longer-term and lesser-known
affects of exposure to low levels of sulphur dioxide. But there's also another
aspect of sulphur dioxide that troubles him - when it reacts with water it
turns into sulphuric acid and becomes far harder and more expensive to monitor.
"Sulphuric acid
becomes apparent over a longer time period than sulphur dioxide and typically
further from the centre of the eruption," he said pointing out the 1783
Laki eruption also killed an estimated 20,000 people in Britain, likely through
exposure to sulphuric acid.
Occasionally, the sulphur dioxide plumes, appearing as a bluish
haze, have reached the capital of Reykjavik on the west coast. But eastern
Iceland has been particularly susceptible to high gas concentrations. Schools
have sometimes been closed andGudnason said sales of asthma drugs have
spiked in the country's east with "indications that various respiratory symptoms
may have increased".
On January 11, a portable meter picked up a reading of 7,800 µg/m3 about
80km east of the eruption.
Sigvaldi Ragnarsson, a sheep farmer in the area, said when he went
outdoors that day he felt a burning sensation in his throat and eyes. He said
the gas built up steadily and stayed for about six to eight hours.
Previously, there had been a higher reading at 8,000 µg/m3,
but he said his symptoms this time were worse, and the pollution was so thick
that when he went into the sheep shed he couldn't see the other end of the
building.
Ragnarsson said he is now worried his livestock could wind up with
long-term damage, as they have been holed up inside the shed with poor air
circulation. "It wouldn't surprise me if the youngest sheep end up with
some health problems, such as weaker lungs," he said.
|
Sulphuric
acid is currently stored in the snow ... [the product of volcanic sulphur
dioxide reacting with water in the atmosphere acidified the snow]. It is only
when the snow melts in spring [that sulphuric acid will affect the water,
soil and vegetation].
Gisli Mar Gislason, University of Iceland
|
Scientists working at
the lava field can be exposed to other gases, such as odourless carbon
monoxide.
Ilyinskaya, the
volcanologist, was with a group that evacuated a site after detecting a carbon
monoxide concentration of 25ppm - the maximum exposure time for this is eight
hours.
"This concentration is not critically dangerous
to human health," she said, but they evacuated as a precaution. "We
travelled some distance to a higher ground until the gas sensor showed a zero
level of carbon monoxide."
Hazards of spring
While the lava flow shows signs of decreasing - and some calculate
the eruption will end in March - come springtime, other side effects of the
eruption could become apparent.
"Sulphuric acid is currently stored in the snow," Gisli
Mar Gislason, a freshwater biology professor at the University of Iceland, told
Al Jazeera.
It is a product of the volcanic sulphur dioxide reacting with
water in the atmosphere and has acidified the snow, he said. It is only when
the snow melts in the spring that sulphuric acid will affect the water, soil
and vegetation, Gislason said.
But there's been one ecological upshot to the eruption. The lava -
at some points as thick as 40 metres - is stabilising sand on a nearby flood
plain that's normally prone to wind erosion.
"An enormous
amount of dust emanates from this area and influences air quality and the
ecology of both land and sea," said Olafur Arnalds, a professor of soil science at the
Agricultural University of Iceland.
The eruption has had a
mitigating effect, according to Arnalds. "The lava is covering many of the
areas that are most susceptible to erosion."
Source: Al Jazeera
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