Earth’s soils contain more than three times the amount of carbon available in the atmosphere, but the processes that bind carbon to the soil are not yet understood.
Developing such an understanding may help researchers to develop strategies for capturing more carbon in soil, thus keeping it out of the atmosphere where it mixes with oxygen and work as a greenhouse gas.
A new study outlines an advanced way to visualize the physical and chemical interactions that capture carbon in soil at near-atomic scales, with remarkable results.
The study, “Organo-Organic and Organo-Mineral Interface in Soil at Nanometer Scale,” was published Nov. 30 in Nature Communication.
At that mission, the researchers showed – for the first time – that ground carbon interacts with both minerals and other types of carbon from organic materials, such as bacterial cell walls and microbial byproducts. Previous imaging research had only identified linear interactions between carbon and minerals in soils.
“If equipment is looked at that could help us retain more carbon in soils, then that will help our climate,” said lead author Johannes Lehmann, Liberty Hyde Professor Bailey in the Department of Integrated Plant Science, Soil and Crop Sciences, College of Agriculture and Life Sciences. Angela Possinger Ph.D. The first author of the paper is ’19, a former graduate student at the Lehmann Laboratory and currently a graduate researcher at Virginia Tech University.
As the purpose of the new device is close to atomic scale, the researchers are not sure what fertilizers they are looking at, but they suspect that the carbon found in soils is likely from metabolites produced by ground microbes and from microbial cell walls. “Apparently, this is a microbial cemetery,” Lehmann said.
“We found an unexpected discovery where we would see an interface between different types of carbon and not just between carbon and minerals,” said Possinger. “We could start looking at these interface facilities and try to understand something about these interactions. “
This method revealed layers of carbon around that organic interface. It also showed that nitrogen was an important player in enabling chemical interactions between both organic and mineral interfaces, Possinger said.
As a result, farmers may improve soil health and reduce climate change through carbon sequestration by considering the form of nitrogen in soil changes, she said.
While pursuing her doctorate, Possinger worked for years with Cornell physics – including co-authors Lena Kourkoutis, associate professor of applied physics and engineering, and David Muller, Senior Samuel B. Eckert Professor of Engineering in Applied Physics and Engineering, and Cornell ‘s co – director of the Kavli Institute for Nanoscale Science – to help develop the multidisciplinary approach.
The researchers intended to use powerful electron microscopes to direct electron conduction down to subatomic plates, but found that the electrons were altering and damaging scattered and complex ground samples. As a result, they had to freeze the samples to around minus 180 degrees Celsius, which reduced the harmful effects from the beams.
“We had to develop a device that will essentially keep the ground grains frozen through the process of making thin chips to look at these tiny resources,” Possinger said.
The beams could then be scanned throughout the sample to produce images of the structure and chemistry of a ground sample and its complex interface features, Kourkoutis said.
“Our physics colleagues are leading the way across the globe to our ability to look closely into material constructions,” Lehmann said. “Without such interdisciplinary collaboration, these developments are not possible.”
The new cryogenic electron microscopy and spectroscopy device will allow researchers to study a full range of interfaces between soft and hard materials, including those involved in the work of batteries, fuel cells and electrolyzers, Kourkoutis said.
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Coauthors include Michael Zachman Ph.D. ’18, who was a graduate student in the Kourkoutis laboratory; Akio Enders, former researcher in the Lehmann laboratory; and Barnaby Levin Ph.D. ’17, who was a graduate student in the Muller laboratory.
The study was funded by the National Science Foundation, Munich Advanced University Technical Institute for Advanced Study, Andrew W. Mellon Foundation and Cornell College of Agricultural and Life Sciences Alumni Foundation.
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