Volcanic ash cloud – the latest news from SEPA – update 5
EXT01 – B05
The Scottish Environment Protection Agency (SEPA) is monitoring
the situation regarding the volcanic ash cloud currently affecting
the UK and its possible impact on Scotland's environment.
SEPA's Director of Science and Strategy, 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.
"The latest rainwater samples analysed also indicate no cause
for concern - pH levels are entirely consistent with normal
rainwater in Scotland.
"We believe, on the basis of the expected deposition patterns
and the nature of the ash, that there is a minimal risk to the
environment."
Ongoing monitoring
SEPA has been carrying out monitoring and analysis on four areas
of the Scottish Environment – ambient air quality; rainwater;
deposited ash particles; and vegetation. Samples collected covering
all these areas are being conveyed to SEPA laboratories by SEPA
staff, Met Office volunteers and partner organisations such as the
Scottish Agricultural College (SAC). Ongoing analysis is being
supported by the Macaulay Institute, Edinburgh University and the
Scottish Avalanche Information Service (SAIS). The picture shows a
typical SEPA solar powered monitoring station.
Typical dust deposition gauge & rain gauge at
Glendye, Aberdeenshire
Air quality
The Scottish Air Quality Database (SAQD) contains the most
up-to-date continuous ambient monitoring information across
Scotland. Members of the public can access this information at
www.scottishairquality.co.uk.
SEPA's most recent assessment of sulphur dioxide
(SO2) at 0600 this morning (20 April) was that
concentrations remain low across Scotland and there have been no
significant increases in pollutants. Therefore, there remains no
cause for concern.
Radiation measurements are taken across the UK and Europe via
the RIMNET monitoring network. Readings show no evidence that the
volcanic ash contains radioactive materials of any
significance.
Rainwater analysis
Preliminary analysis of 13 samples, 11 from rainwater and two
from snow, have been carried out for pH and fluoride levels. pH
measures the concentration of hydrogen ions in solution and is the
commonly accepted measure of acidity and alkalinity, using pH
units that range from 0 to 14, with 0 to 7 reflecting acidic
conditions, 7 neutral and 7-14 alkaline conditions.
Rainwater in Scotland is normally between 4 and 7 pH units.
Occasional acidic events are observed in Scotland and pH readings
can be as low as 2.5.
The results from the samples analysed by SEPA yesterday are all
between 4 and 7 pH units and as such are typical of normal Scottish
rainfall.
Currently, a selection of the rainwater samples have also been
analysed for fluoride. Results indicate that levels present in the
sample are less than 0.05 milligrams per litre. This is very
low and is more than an order of magnitude lower than the UK
safe levels for drinking water. The national and international
drinking water standard is 1.5 milligrams per litre.
All of the results above indicate that there is no cause for
concern.
Deposited ash analysis
SEPA is monitoring deposits of ash right across the country and
deposition rates remain low.
Below is a sticky pad showing dust deposited in Shetland over
the weekend. Although it appears to be a very boring picture, it
provides us with a very interesting result - it shows that very few
dust particles are being deposited.
Two further samples of volcanic ash, collected in Shetland, were
received at SEPA's Aberdeen laboratories on Monday 19 April.
Sample one was taken from a SEPA staff member's car at Burgh
Road, Lerwick. It was collected on a white cloth and the
cloth containing the sample was moist. The sample was of dark grey
appearance.
Sample two was collected from South Whiteness, from the roof of
a Nissen hut, and was collected on a piece of white paper towel.
The sample was dry and of dark grey appearance.
After initial analysis, both samples were transferred to the
Macaulay Institute for further analysis.
Sample One – Burgh Road, Lerwick
Under microscopic examination, the sample appeared to have a
crushed glass appearance, with angular glassy shards evident. These
were interspersed with some dark grey particles. Particles varied
in size from 45 x 15µm to 188 x 30µm.
Figure 1: Sample One at 200x magnification
Figure 2: Sample One at 400x magnification (central
shard = 45 x 15µm)
Figure 3: Sample One at 400x magnification (shard = 188
x 30µm)
The majority of the particles examined revealed a glassy type
material which was angular with conchoidal fractures and which
comprised a more complex composition than quartz. The morphology
and composition was similar to that of samples which had been
previously analysed. A few crystallised silicate grains (quartz)
were also evident and these exhibited a very simple composition of
Si and O. The latter are most likely to be background
contamination.
Figure 4: SEM analysis of sample 1 displaying glassy
material & quartz
Figure 5: SEM analysis of sample 1 displaying glassy
material
Sample Two – South Whiteness
Under microscopic examination, the sample appeared to have a
crushed glass appearance, with angular glassy shards evident. These
were interspersed with dark grey particles. There was evidence of
red coloured particles of glassy appearance. Particles ranged in
size from 20 x 18µm to 230 x 178µm.
Figure 6: Sample Two at 200x magnification (shard = 214
x 102µm)
Figure 7: Sample Two at 200x magnification (shard = 230
x 178µm)
Figure 8: Sample Two at 400x magnification (shard = 200
x 150µm)
Figure 9: Sample 2 at 400x magnification (shard = 20 x
18µm)
This sample exhibited a wider variety of particle sizes than
both Sample One and the sample obtained on Thursday 16 April. The
analysis showed that the larger particles tended to be of different
composition to the glassy material in the other samples, indicating
that they were not the same. Compositional analysis suggests that
these are muscovite and/or mica type materials and most likely of
environmental origin. Many of the smaller particles exhibited
similar conchoidal fracture and composition of the glassy material
in the other samples, indicating they are comparable and most
likely of volcanic origin. The higher incidence of environmental
background particles in this sample is most likely due to the
location the sample was taken from i.e. unlikely to have been
sufficiently clean prior to atmospheric deposition.
Figure 10: SEM analysis of sample two displaying varied
particle sizes
Vegetation
On behalf of SEPA, the Scottish Agricultural College (SAC) is
collecting samples of grass from across Scotland. SEPA scientists
will wash the samples and analyse the run off to ascertain if there
are any potential hazards for grazing animals and the wider
environment. Given that no adverse effects have been observed
in rainwater and dust deposits, we do not expect to see any issues
on concern.
Future work
Although it is Spring, there have been recent snowfalls in
upland areas across Scotland! Snow is a particularly good medium
for absorbing dust particles from the atmosphere. The Scottish
Avalanche Information System (SAIS) is now collecting samples of
snow on behalf of SEPA and transporting them to our laboratories.
As we have already analysed two samples of snow, again we do not
expect to find any areas of concern, but this will allows us to
provide further reassurance about the environmental impacts.
We will continue our environmental monitoring until the
Icelandic eruption subsides.
ENDS
Notes to editors
Environmental monitoring sites include 75 sites air quality
monitoring sites (results available live on www.scottishairquality.co.uk).
SEPA also uses data from other local air quality monitoring sites
across Scotland.
SEPA evaluates the results from 25 radioactivity monitoring
sites across the country. Some locations also have dust filters
that are being collected for analysis not only for their normal
purpose but also to provide additional samples for volcanic dust
analysis.