Brownfield soil has a surprisingly high ability to trap CO2 from the atmosphere

Brownfield sites ‘incredibly efficient’ in capturing atmospheric CO2

Image credit: Petr Vilgus

Brownfields could play a significant role in the fight against climate change as the soil containing demolition waste is extremely efficient in trapping carbon dioxide, researchers have found.

Demolition waste containing concrete, dust and lime is rich in calcium, which efficiently binds carbon dioxide from the atmosphere and locks it in the form of calcium carbonate, or calcite.

The research project called SUCCESS led by Newcastle University researchers found that one hectare of brownfield soil can capture and lock up to 85 tonnes of atmospheric carbon per year.

“Scaling that up, appropriate management of less than 12,000 hectares of urban land to maximise calcite formation could remove 1 million tonnes of CO2 from the atmosphere each year,” explained Professor David Manning who led the study.

The UK has 1.7 million hectares of urban land. The researchers calculated that properly managing only 40 per cent of this land could meet 10 per cent of the UK’s annual CO2 reduction target.

“The soil beneath our feet is a major reservoir for carbon,” said Mark Goddard of Newcastle University. “Our research shows that we mustn’t neglect brownfield soils because they have huge potential for carbon capture via a process called ‘carbonation’.”

Brownfield soils sequester carbon from the atmosphere much more quickly than natural peatlands.

The researchers believe the soil could be specially engineered to capture and store carbon even more efficiently. The use of specific types of plants could further enhance the effect by channelling carbon dioxide from the atmosphere into the soil.

The research project, funded by the Engineering and Physical Sciences Research Council, focused on 21 brownfield sites across Tyneside and Teesside. The researchers measured soil carbon levels and monitored how wildlife recolonises the once industrial land.

“We encountered a great variety of sites – from a recently demolished hospital comprising little but brick rubble and a few brave, early colonising plants, through to long abandoned ex-industrial sites now supporting a myriad of wildlife, including deer, skylarks, ringed plovers, rare insects and bee orchids,” Goddard said.

The researchers envision carbon capture gardens could be created in urban green spaces in future, soaking up CO2 but also providing environment for recreation and wildlife.

The UK’s 23 million gardens occupy some 433,000 hectares. If a carbon capture function was built in to just 1 per cent of this area, they could remove 300,000 tonnes of CO2 from the atmosphere each year.

“We are a nation of gardeners, and we see carbon capture gardens as an exciting opportunity to increase people’s awareness of carbon capture and to show them that there is something simple that they can do locally to compensate for climate change through soil management associated with gardening and landscaping activities,” said Goddard.

“For such initiatives to succeed, we must take soil and vegetation management much more seriously in urban developments, including urban brownfield sites, green space around transport infrastructure, and in land remediation and restoration.”

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