As volcanic ash fallout is predicted to reach ground level following the eruption of the Eyjafjallajökull volcano in Iceland, scientists from the Centre for Ecology & Hydrology have responded rapidly to increase sampling rates of air quality, soils and vegetation at its long-term monitoring sites across the UK.
CEH operates a number of long-term monitoring programmes in the UK, including the Environmental Change Network (ECN), the UK EMEP supersite in Scotland which measures air pollutants, and the Acid Waters Monitoring Network (AWMN). The ECN collects, stores, analyses and interprets long-term data based on a set of key physical, chemical and biological factors which drive and respond to environmental change at more than 50 terrestrial and freshwater sites across the UK.
Since the volcanic eruption episode began, CEH scientists have increased existing sampling rates, particularly where extra data may give further information on changes in levels of acidity, sulphur, mercury and fluoride.
"We are installing intensive monitoring systems at several locations to examine whether sulphur from the ash could cause pulses of acidity in our streams."
Chris Evans, Centre for Ecology & Hydrology
Levels of fluoride are being analysed in waters, soils and vegetation. CEH’s Auchencorth site in Scotland has been measuring air mercury levels since the morning of 16 April when the volcanic ash began to drift over northern Europe. Results from the last week show no noticeable increase in mercury concentration, although this could change as the plume continues to reach ground level. Analysis is ongoing for other elements.
Atmospheric monitoring of air quality continues with daily rain samples and fortnightly bulk rain chemistry analysis at 38 sites. At eight sites this has been increased to weekly measurements in response to a request from Defra for fluoride analysis to be carried out for the duration of the volcanic plume event.
In addition, ongoing intensive sampling is underway for a range of CEH catchments to identify potential acidification in freshwater. Vegetation samples are being collected from a wide range of sites, with particular interest in the Pennines and the South East area where most of the deposition appears to be concentrated.
As the volcanic eruption develops, CEH will continue to collect samples of interest to feed into these long term trends and monitoring programmes. Analysis of results will help to provide evidence to inform policy-makers and encourage appropriate action in light of future volcanic ash developments.
Chris Evans, a biogeochemical modeller from the Centre for Ecology & Hydrology, said any effects of volcanic ash deposition on soil and water quality should be detectable at various CEH long-term monitoring sites across the UK. “We are installing intensive monitoring systems at several locations to examine whether sulphur from the ash could cause pulses of acidity in our streams – there is evidence that this happened after previous Icelandic eruptions.”
Some scenarios, from computer models developed at CEH, suggest that “a severe sulphur deposition event could trigger levels of stream and lake acidity not witnessed since the ‘acid rain’ peak of the 1970s to 80s.” However, Dr Evans added that presently “we do not expect the current eruption to have impacts on this scale.”
Details of CEH's long-term monitoring programmes
More about the UK Environmental Change Network
Operation of EMEP 'supersites' in the United Kingdom, Annual Report 2007