Toxic heavy metals stored in the UK’s peatlands could pose serious health risks to humans, animals, and agriculture if these ecosystems are not properly maintained, researchers at Queen’s University Belfast have warned.
They caution that wildfires and the ongoing impacts of climate change could release decades’ worth of pollutants—such as lead, arsenic, mercury, and cadmium—into natural water systems.
The health hazards posed by these substances are already known. A medical expert previously linked cadmium contamination at a former steelworks in Corby, Northamptonshire, to birth defects in animals.
The researchers argue that their findings underscore the urgency of re-wetting and restoring peatlands in order to safeguard both environmental and public health.
Peatlands are renowned carbon sinks, storing greenhouse gases in their waterlogged soils. However, they have also absorbed industrial pollutants for over two centuries.
The team at Queen’s University Belfast, led by Professor Graeme Swindles, has been analysing peat cores from across the UK, Ireland, and beyond, as part of a global research initiative involving numerous institutions.
Traces of long-stored pollution have even been discovered in samples taken from the remote Arctic North.
“It’s quite staggering to find such high levels in our peatlands that you think are these incredibly pristine places in many ways,” said Prof Swindles.
“But no – they have been affected by our pollution.”
PhD student Ellie Purdy, who described herself as eager to join the project, said the findings raise real concerns for the future.
“It’s basically just about how what we’re doing is affecting the environment,” she said.
“And even though these contaminants were once stored in these peatlands they’re now being released under climate warming.”
Her research has focused on cores from Ellesmere Island in the Canadian High Arctic. Discovering heavy metal contamination in such an isolated region with minimal human activity was, she said, “eye-opening”.
“It just shows how connected we are throughout the globe,” she said.
Peatlands cover approximately 12% of Northern Ireland, but their ability to sequester carbon depends on their condition. When healthy, they accumulate new peat at a rate of just 1mm per year. However, more than 80% of peatlands are currently in a degraded state—primarily due to burning and drainage for peat extraction.
Laboratory experiments at QUB are investigating how climate change could affect peatland stability.
Dr Richard Fewster has examined three likely future scenarios: a warming climate, wildfires, and summer droughts.
While all have an impact on peatland dynamics, he found that fire poses the greatest threat.
Dr Fewster said: “We’re seeing that burning actually mobilises some of the metals within the peatland much more rapidly, in a sort of a ‘big pulse’ event early on in the experiment that we don’t see in cores that are left intact.
“So one of the really early findings that we have is that protecting our systems in a wet, stable, intact condition is really important for locking these peat metals, these pollutants, away in our peatlands and preventing them from being released.”
A long-awaited peatland strategy from the Department of Agriculture, Environment and Rural Affairs is still awaiting Executive approval.
Northern Ireland’s draft Climate Action Plan states that annual peatland restoration must be “dramatically increased” to meet the Climate Change Committee’s target of restoring 10,000 hectares by 2027.
At Garry Bog, near Ballymoney in County Antrim, over 3,000 dams have been installed to block drainage channels and raise the water table.
The peat at Garry Bog extends to depths of at least nine metres, indicating that it has been forming—and storing carbon—for more than 9,000 years.
James Devenney from Ulster Wildlife, who is leading the restoration efforts at the site, described peatlands as our most important and impactful terrestrial carbon sinks.
“So the fact that we have 12% cover in Northern Ireland of peatlands – deep peat in a lot of cases that’s greater than 50 centimetres – there’s a huge scope of work that can be done.
“Northern Ireland has a big part to play in tackling climate change.”
Professor Swindles said the message from his team’s research at QUB could not be clearer.
“It’s really clear we need to ensure these peatlands are kept wet. We need to restore them, rehabilitate them, block drains.
“And we need to stop burning peatlands.”
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At Natural World Fund, we are passionate about restoring habitats in the UK to halt the decline in our wildlife.
