SEPA's director of Science and Strategy, (right)Professor James Curran, said: 

"The greatest environmental concern from volcanic ash, and the most significant risk to grazing livestock, would be fluoride content in ash deposits.

Information from SEPA's analysis of Scottish dust samples, and from similar analysis in Norway, indicates low levels of fluoride in the current Icelandic ash plume.

"We think, on the basis of the expected deposition patterns and the nature of the ash, that there is a  minimal risk to the environment."



Continuous environment monitoring will be ongoing over the weekend and beyond, using information about from a wide network of existing environmental monitoring sites across Scotland.

SEPA and the Met Office will also attempt to collect rainwater samples over the weekend of 17-18th April.


These will be analysed by SEPA for pH and soluble fluoride. 

Radiation measurements taken across the UK and Europe indicate there is no evidence that the volcanic ash contains radioactive materials of any significance. 



The Scottish Air Quality Database contains the most up-to-date continuous ambient monitoring information across Scotlandand is open to members of the public.  All concentrations have remained low at all monitoring sites across Scotland.

Latest results from SEPA's dust analysis 

SEPA analysed three dust samples collected in Lerwick, Aberdeen and East Kilbride. 
Initially a small portion of the Lerwick sample was placed on a microscope slide for examination. The sample was dark grey, black in appearance. Under microscope there were aggregrates of dark grey, black particles possibly opaque material covered in a dark deposit. This was interspersed with regular shaped angular particles of glassy appearance.

The particles ranged in size from 15 x 20 micronmetre to 70 x 85 micronmetre. 

The Aberdeen sample was also examined and was found to contain angular particles of glassy appearance and were approximately 60 x 70micornmetre in size.

Further analysis conducted by the Macaulay Institute (right) shows broadly uniformed sized (approx. 20 micronmetre) particles of angular shape some exhibiting striations and others conchoidal (smooth curved surfaces) fractures (typical of quartz and glass). 



Most particles showed similar composition consisting of silicon, oxygen, aluminium, sodium, calcium, magnesium, potassium, iron and chloride. There was no evidence of high concentrations of fluorine in this sample. 

Based on the morphology of the particles (angular with conchoidal fracture faces) and the fairly uniform elemental composition of the particles it is likely that the sample is of volcanic origin.

The sample collected at East Kilbride was examined by microscopy in East Kilbride and also found to contain glassy, angular particles which were identified as 'new silica' ie sharp, bright and clear as opposed to smooth and opaque. This is typical of volcanic material.

NORWEGIAN FOOTNOTE

How long will the eruption of the Eyjafjallajokull volcano continue and what other kinds of activity can we expect? A volcanologist at the Norwegian University of Science and Technology (NTNU)  who has worked extensively in Iceland says a month-long eruption would not be out of the question. But the eruption could also continue for a year or more, he says.

Professor Reidar Trønnes, (right) who was a research scientist at the University of Iceland’s Nordic Volcanological Institute from 2000 to 2004, says as eruptions go, the Eyjafjallajokull volcano is not that large. Nevertheless, concerns about the effects of volcanic ash on jet engines led to a range of airport closures in northern Europe on Friday.

Trønnes says that the ash gets shot high into the air as magma that was once deep in the Earth comes to the surface and is depressurized. Any water that has dissolved in the magma comes boiling out when the magma is no longer under pressure, much the way that CO2 bubbles out of your selzer water when the cap is removed, he says. The plume coming out of the Eyjafjallajokull volcano also contains a good deal of steam because the intensely hot magma is melting the ice cap that blankets the volcano, he adds.
 
While the Eyjafjallajokull volcano’s eruption is highly dramatic, most volcanologists like Trønnes are watching the volcano’s much larger neighbour (right) to the east, Katla.

This volcano, buried under the Mýrdalsjökull glacier, Iceland’s fourth largest ice sheet, usually erupts twice a century,
Trønnes says, but has erupted just once in the last 100 years – in 1918.

“Katla has had two large eruptions every century since Iceland was settled 1,100 years ago,” he said. “It is long overdue – or it could mean that Katla has changed its behaviour.”

A number of large volcanic eruptions over the last several decades may have helped drain the vast magma reservoirs that would feed any eruption of Katla, says Trønnes. These include eruptions as far back as one that created the island of Surtsey in 1963-1967 and one that took place on nearby Heimaey in 1973.

“The fact that we have had these two large eruptions in the 1960s and 1970s may have relieved the pressure in the Katla reservoir, although this is just speculation,” he said.

The Eyjafjallajokull volcano now appears to have released enough pressure that Trønnes does not expect any large-scale explosions, but the melting of the glacier caused by lava flows will continue to pose risks of potentially large and devastating floods.