UK shale has lots of poisonous selenium scientists warn

UK shale has lots of poisonous selenium, an element our body uses in tiny amounts, but is toxic to humans when levels are high – and levels of selenium in rock samples taken by an international team led by the University of Aberdeen from an area targeted for shale gas extraction in the UK are very high.

Symptoms of selenosis (selenium poisoning) include garlic-smelling breath, hair loss, fatigue, irritability, sloughing of nails, gastrointestinal disorders, and neurological damage. In extreme cases the patient can develop cirrhosis of the liver, pulmonary edema, and may die.

The researchers, from the Aberdeen University’s School of Geosciences, Australia’s National Science Agency, and the Commonwealth Scientific and Industrial Research Organisation (CSIRO) in Australia, wrote about their study and its findings in the academic journal Applied Geochemistry. Toxic levels of selenium were found in rock samples taken from the Bowland Shale, a geological formation that is rich in shale gas in the north of England.

Abnormally high selenium levels in shale rock samplesScientists have found toxic levels of selenium in the Carboniferous Bowland Shale. (Image: University of Aberdeen)

Risk of selenium getting into groundwater

The authors said there is a serious risk that high levels of selenium could be released into groundwater during ‘fracking’ (drilling) operations. Fracking companies need to be extremely careful during extraction to make sure that levels are kept to a minimum.

Study leader, Professor John Parnell, said:

“A major factor to be considered during shale gas drilling is the accompanying water, which may contain chemicals that require careful treatment.”

“Recently, there was widespread concern in the US when water wells near a shale drilling site were found to contain selenium at levels that exceeded the maximum amount considered safe to drink, and this was assumed to have been released from the shale during drilling.”

“The samples we have analysed from the Bowland Shale are some of the most selenium-rich in the British Isles, and far in excess of the levels of selenium found in the US example. Indeed, a number of the samples we tested exceeded the far stricter European Union limits, so it is clear that any drilling to extract shale gas in the Bowland Shale area must be carefully managed.”

Same problem in Ireland

The study also found high selenium levels in equivalent rocks in the Republic of Ireland. Scientists know that shales in Ireland have caused selenium toxicity in farm animals “further underlying the importance of the issue.”

Bowland Shale areaThe Bowland Shale area covers much of the North of England. (Image:

However, in spite of these concerns, high levels of selenium in the Bowland Shale offer opportunities, the scientists added. Selenium is a rare element in high demand – this demand is likely to grow.

Professor Parnell said:

“While this is first and foremost an environmental issue, the concentration of selenium and other trace elements in extraction waters could be regarded as an opportunity.”

Bowland Shale samplesMap showing sampled localities in Bowland Shale Formation, and localities for Se/As-rich oil residues. A, Altmush; B = Ballybunion; D, Dunshaughlin; E = Edale; H = Holywell; K = Killadysert; L, Co. Leitrim (Glenfarne, Thur Mountain); M = Poyllvaaish, Isle of Man; P = Pendle Hill and Earby; R = Walmsley Bridge; S = Loughshinny; T = Trough of Bowland; V = Lisdoonvarna; W, Whalley and Wiswell. (Image: Applied Geochemistry)

“Selenium is a rare element for which demand is likely to increase, so there is a commercial incentive here which companies will no doubt be mindful of.”

“This study emphasises the importance of research when looking at areas to explore, in order to be fully aware of the potential impacts.”

What is fracking?

Fracking, or hydraulic fracturing, is a procedure that creates fractures in rocks and rock formations. Fluid is injected into cracks to force them to open up further.

As the cracks (fissures) open up, more oil and gas flows out of the rocks and into a wellbore, from which the fossil fuel can be extracted.

Since the turn of the century, fracking has become a multi-billion dollar business in the United States. It has helped the country become almost self-sufficient in fossil fuels, and will soon be a net exporter.

Citation: “Selenium enrichment in Carboniferous Shales, Britain and Ireland: Problem or opportunity for shale gas extraction?” John Parnell, Connor Brolly, Sam Spinks, Stephen Bowden. Applied Geochemistry. December 2015. DOI: 10.1016/j.apgeochem.2015.12.008.

Video – What is Fracking?

Perhaps you have heard about fracking but are not sure what it is. Politicians and lobby groups are arguing about it a lot these days. This video explains in simple terms what fracking is.