Scientists from the University of Cambridge and NTU in Singapore have found that the slow collision of tectonic plates is pulling more carbon into the Earth’s interior than previously thought.
They found that carbon pulled into the Earth’s interior in subduction zones – where tectonic plates collide and sink into the Earth’s interior – tends to remain beyond depth, rather than emerge as volcanic emissions.
“We currently have a relatively good understanding of surface carbon reservoirs and flows between them, but we know very little about Earth’s internal carbon stores, which recycle carbon over millions of years.” – Stephen Farsang
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Their findings, published in Natural Communication, suggesting that about a third of the carbon recycled under volcanic chains returns to the surface via recycling, in contrast to the previous theory that what falls mostly returns to the surface.
One solution to tackling climate change is to find ways to reduce the amount of carbon dioxide2 in the earth’s atmosphere. By studying how carbon behaves deep within the Earth, which comprises most of the carbon on our planet, scientists can better understand the entire life cycle of carbon on Earth, and how carbon flows between the atmosphere, oceans, and life on the surface.
The best understood part of the carbon cycle is at or near the Earth’s surface, but deep carbon stores play a key role in maintaining our planet’s viability by regulating carbon dioxide in the atmosphere.2 level. said lead author Stephane Farsang, who conducted the research while a PhD student in the Department of Earth Sciences at Cambridge University.
There are several ways that carbon is released back into the atmosphere (such as carbon dioxide2But there is only one way to get back into the Earth’s interior: through plate subduction. Here, surface carbon, for example in the form of shellfish and microorganisms that trap carbon dioxide in the atmosphere2 In their shells, they are directed towards the ground. Scientists believe that most of this carbon then returns to the atmosphere in the form of carbon dioxide2 by emissions from volcanoes. But a new study reveals that chemical reactions in ingested rock in subduction zones trap carbon and send it deeper into the Earth’s interior – preventing some of it from returning to the Earth’s surface.
The team conducted a series of experiments at the European Synchrotron Radiation Facility, and co-author Simon Redfern, Dean of the Faculty of Science at NTU Singapore, said: “ESRF has world-leading facilities and the expertise we needed to get our results. “This facility can measure very low concentrations of these metals under conditions of high pressure and temperature which are of interest to us.” To mimic the high pressure and temperature in the area of the eruption, they used a hot “diamond anvil,” where extreme pressure is achieved by pressing two tiny diamond anvils into the sample.
The work supports growing evidence that carbonate rocks, which have the same chemical composition as limestone, become less calcium-rich and more magnesium-rich as they are channeled deeper into the mantle. This chemical shift makes the carbonates less soluble – meaning they are not attracted to the liquid that supplies the volcano. Instead, most of the carbonates sink deep into the mantle where they can eventually become diamonds.
“There is still a lot of research to be done in this area,” says Varsang. “In the future, we aim to improve our forecasts by studying the solubility of carbonates over a wider temperature, pressure range, and in many fluid compositions.”
The findings are also important for understanding the role of carbonate formation in our general climate system. Our results show that this mineral is very stable and can definitely trap CO2 from the atmosphere into solid mineral forms that can cause negative emissions,” said Redfern. The team is looking for a similar method to capture carbon, which moves carbon dioxide into the atmosphere.2 In storage in rocks and oceans.
These results will also help us understand better ways to sequester carbon on Earth’s dense, outer atmosphere. If we can accelerate this process faster than nature is handling, this could be a way to help solve the climate crisis,” said Redfern.
Reference: “The deep carbon cycle is limited by carbonate solubility” by Stephane Farsang, Marion Lovell, Chushuai Zhao, Mohamed Mezouar, Angelica de Rosa, Remo N. Widmer, Xiaoli Feng, Jin Liu, and Simon AT Redfern, July 14, 2021, Natural Communication.
DOI: 10.1038 / s41467-021-24533-7
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