The name “critical zone” might give off a 1980s action thriller vibe, but it’s a term scientists use to refer to the regions of the Earth’s land surface that are involved in sustaining life. A relatively small portion of the planetary structure, extending from the bedrock beneath the groundwater to the lower atmosphere.
“Think of it as the skin of the earth,” said John Chover, director of the Department of Environmental Sciences at the University of Arizona’s School of Agricultural and Life Sciences. “Sometimes called The Zone Where Rock Meets Life.”
Most people, even geologists, don’t usually think of rocks as the basis for life, or that life can change rocks, but that gets to the heart of critical zone science. Mr Chover says.
A relatively new framework for approaching the Earth sciences, Critical Zone brings together researchers from different disciplines to work together on physical, chemical and biological process Collectively, they form the Earth’s life support system.
As a biogeochemist, a whole-systems approach is a natural way of thinking for Chowber, who has spent much of his career figuring out how chemicals and chemicals change. mineral weathering Evolve everything from soil Microbiome to carbon cycle.
Along with Qian Fang, a postdoctoral researcher at Peking University in Beijing, Chorover recently presented results from nearly a decade of data collected at the Santa Catalina-Jemez River Basin Critical Zone Observatory. northern New Mexico and southern Arizona.
According to Chowber, their findings provide “conclusive evidence” between carbon-consuming microbial activity and the transformation of rocks into life-sustaining soils in critical zones.
open-air living laboratory
In the past, measuring things like mineral weathering was often less exciting. Imagine a researcher breaking a chunk of rock and watching it melt back into the lab into a beaker. But seeing that process in a natural ecosystem is another story.
At the Santa Catalina-Jemez Basin Critical Zone Observatory, a tower that measures water exchange between forests and the atmosphere, soil probes that read energy and gas transfers, and a host of other instruments in the environment provide scientists with Provides a first-hand view. of complex systems within the critical zone.
The site is part of the larger National Science Foundation Critical Zone Observatory program and unlike traditional brick-and-mortar observatories, it offers a network of regional ecological environments with scientific instruments across the United States. .
The site’s temperature, humidity, and gas sensors collected readings every 15 minutes, and after compiling and correlating the data, “What we found was strong relationship It’s between the rate at which rocks weather and form soil and the activity of the subsurface microbiome,” said Chowber, principal investigator at the Catalina Jemez Observatory.
Breaking down rocks into lifecycles
“Minerals, microbes and organic matter are among the most important building blocks on the surface of the earth,” Fang said. “They constantly interact with each other to provide nutrients, energy and a suitable living environment for all life on Earth.”
These minerals in the critical zone are continuously attacked by microorganisms, organic acid And water, explained Fang. As the minerals break down, microorganisms in the soil consume the new organic matter, releasing carbon dioxide and converting it into substances that plants and other microorganisms can feed on.
Previous studies suggest microbial degradation of soil organic matter Having more “fresh” organic matter can provide energy. vegetable matter— introduced into the soil system. This process is called the “priming effect” by soil scientists. However, the relationship between mineral weathering and microbial priming remains unclear.
“Our study shows for the first time how these important soil processes are combined and how these two processes continuously affect soil formation, CO.2 Mr Fang said: “These associations may even be related to long-term elemental cycling and rapid turnover of soil carbon and nutrients on Earth.”
While it’s easy to perceive the success of plants and microbes as lucky environmental conditions, Chorover said the study proves that even the smallest parts of critical zones play an important role. .
“This shows that life is not just a passive passenger on the evolutionary trajectory of the Critical Zone, but is actually an active engineer determining the direction and course of how the skin of the Earth evolves. It shows,” said Chover.
My work was published in a magazine Nature Communications.
For more information:
Qian Fang et al., Mineralweathering relates to microbial priming in critical zones. Nature Communications (2023). DOI: 10.1038/s41467-022-35671-x
University of Arizona
Quote: Microbes are the ‘active engineers’ in the Earth’s rock-to-life cycle (Feb. 2, 2023). html
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