From The University of Arizona: “Microbes are ‘active engineers’ in Earth’s rock-to-life cycle”
From The University of Arizona
2.1.23
Jake Kerr and Rosemary Brandt | College of Agriculture and Life Sciences
An open-air, living laboratory that spans parts of Arizona and New Mexico is helping researchers better understand how mineral weathering – the breaking down or dissolving of rocks and minerals over time – feeds into Earth’s intricate life-support system.
An eddy covariance tower helps researchers measure forest-atmosphere exchanges of gas and water in the Santa Catalina Mountains in Arizona. Courtesy of The University of Arizona Department of Environmental Science.
The name “critical zone” may give off 1980s action thriller vibes, but it’s the term scientists use to refer to the area of Earth’s land surface responsible for sustaining life. A relatively small portion of the planetary structure, it spans from the bedrock below groundwater all the way up to the lower atmosphere.
“Think of it as Earth’s skin,” said Jon Chorover, head of the Department of Environmental Science in the University of Arizona College of Agriculture and Life Sciences. “It’s sometimes termed the zone where rock meets life.”
Most people – even geologists – don’t typically think about rock as the foundation of life or the way life may alter rock, but that cuts to the heart of critical zone science, Chorover said.
A relatively new framework for approaching Earth sciences, the critical zone aligns researchers across disciplines to better understand how the delicate web of physical, chemical and biological processes come together to form Earth’s life-support system.
As a biogeochemist, the whole-system approach is a way of thinking that comes naturally to Chorover, who has spent much of his career working to unravel the ways in which chemical and mineral weathering drives the evolution of everything from the soil microbiome to the carbon cycle.
Together with Qian Fang, a postdoctoral researcher from Peking University in Beijing, Chorover recently published the results [Nature Communications (below)] of nearly 10 years of data collected at the Santa Catalina-Jemez River Basin Critical Zone Observatory – which spans a gradient of elevation and climates on rock basins in northern New Mexico and Southern Arizona.
Fig. 1: A conceptual model showing the relationship of weathering congruency to the priming effect.
Mineral breakdown at high and low weathering congruencies results in different proportions of dissolved vs. solid-phase products (Table 1). High weathering congruency yields more dissolved cations and fewer solids relative to low congruency. Low congruency generates more short-range-order minerals that can bond with and protect organic matter (including dissolved organic matter-DOM) through formation of mineral-organic associations, which are inaccessible to microorganisms and, thus, influence the priming effect. The more limited production of solid phases at high congruency limits bonding and precipitation of dissolved organic matter, thus facilitating the priming of soil organic matter.
Their findings, according to Chorover, provide a “smoking gun” link between the activities of carbon-consuming microbes and the transformation of rock to life-sustaining soil in the critical zone.
An open-air, living laboratory
In the past, measuring something like mineral weathering often wasn’t that exciting — imagine researchers breaking off chunks of rock and watching it dissolve in beakers back at the lab. But viewing that process in a natural ecological system is a different story.
At the Santa Catalina-Jemez River Basin Critical Zone Observatory, towers that measure the exchange of water between the forest and atmosphere, soil probes that read the transfer of energy and gases, and a host of other in-environment instrumentation offer scientists a firsthand view of the complex systems within the critical zone.
The site is part of a larger National Science Foundation Critical Zone Observatory program, which unlike traditional brick-and-mortar observatories provides a network of regional ecological environments rigged with scientific instrumentation across the United States.
Temperature, moisture and gas sensors at the site collect measurements every 15 minutes, and after compiling and correlating the data, “What we found was a strong relationship between the rate at which the rock was weathering to form soil and the activities of the microbiome in the subsurface,” said Chorover, a principal investigator at the Catalina-Jemez observatory.
Breaking down the rock-to-life cycle
“Minerals, microorganisms and organics are among the most important components in Earth’s surface,” Fang said. “They interact with each other constantly to provide all terrestrial life with nutrients, energy and suitable living environments.”
These minerals in the critical zone are continuously attacked by microorganisms, organic acids and water, Fang explained. As the minerals break down, microbes in the soil consume the new organic matter and transform it into material that feeds plants and other microorganisms, while releasing carbon dioxide.
Previous studies suggest that microbial decomposition of soil organic matter can be fueled when more “fresh” organics – such as plant matter – are introduced to 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 essential soil processes are coupled, and these two processes continuously influence soil formation, CO2 emission and global climate,” Fang said. “The linkages may even be associated with long-term elemental cycling and rapid turnover of soil carbon and nutrients on Earth.”
While it is easy to perceive the success of plants and microorganisms as lucky environmental circumstance, Chorover said this study proves even the smallest parts of the critical zone have a substantial role to play.
“It shows that life is not simply a passive passenger on the trajectory of critical zone evolution, but actually an active engineer in determining the direction and path of how the Earth’s skin evolves,” Chorover said.
See the full article here .
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As of 2019, The University of Arizona enrolled 45,918 students in 19 separate colleges/schools, including The University of Arizona College of Medicine in Tucson and Phoenix and the James E. Rogers College of Law, and is affiliated with two academic medical centers (Banner – University Medical Center Tucson and Banner – University Medical Center Phoenix). The University of Arizona is one of three universities governed by the Arizona Board of Regents. The university is part of the Association of American Universities and is the only member from Arizona, and also part of the Universities Research Association . The university is classified among “R1: Doctoral Universities – Very High Research Activity”.
Known as the Arizona Wildcats (often shortened to “Cats”), The University of Arizona’s intercollegiate athletic teams are members of the Pac-12 Conference of the NCAA. The University of Arizona athletes have won national titles in several sports, most notably men’s basketball, baseball, and softball. The official colors of the university and its athletic teams are cardinal red and navy blue.
After the passage of the Morrill Land-Grant Act of 1862, the push for a university in Arizona grew. The Arizona Territory’s “Thieving Thirteenth” Legislature approved The University of Arizona in 1885 and selected the city of Tucson to receive the appropriation to build the university. Tucson hoped to receive the appropriation for the territory’s mental hospital, which carried a $100,000 allocation instead of the $25,000 allotted to the territory’s only university. (Arizona State University was also chartered in 1885, but it was created as Arizona’s normal school, and not a university). Flooding on the Salt River delayed Tucson’s legislators, and by the time they reached Prescott, back-room deals allocating the most desirable territorial institutions had been made. Tucson was largely disappointed with receiving what was viewed as an inferior prize.
With no parties willing to provide land for the new institution, the citizens of Tucson prepared to return the money to the Territorial Legislature until two gamblers and a saloon keeper decided to donate the land to build the school. Construction of Old Main, the first building on campus, began on October 27, 1887, and classes met for the first time in 1891 with 32 students in Old Main, which is still in use today. Because there were no high schools in Arizona Territory, the university maintained separate preparatory classes for the first 23 years of operation.
Research
The University of Arizona is classified among “R1: Doctoral Universities – Very high research activity”. UArizona is the fourth most awarded public university by National Aeronautics and Space Administration for research. The University of Arizona was awarded over $325 million for its Lunar and Planetary Laboratory (LPL) to lead NASA’s 2007–08 mission to Mars to explore the Martian Arctic, and $800 million for its OSIRIS-REx mission, the first in U.S. history to sample an asteroid.
National Aeronautics Space Agency OSIRIS-REx Spacecraft.
The LPL’s work in the Cassini spacecraft orbit around Saturn is larger than any other university globally.
National Aeronautics and Space Administration/European Space Agency [La Agencia Espacial Europea][Agence spatiale européenne][Europäische Weltraumorganization](EU)/ASI Italian Space Agency [Agenzia Spaziale Italiana](IT) Cassini Spacecraft.
The University of Arizona laboratory designed and operated the atmospheric radiation investigations and imaging on the probe. The University of Arizona operates the HiRISE camera, a part of the Mars Reconnaissance Orbiter.
U Arizona NASA Mars Reconnaisance HiRISE Camera.
NASA Mars Reconnaissance Orbiter.
While using the HiRISE camera in 2011, University of Arizona alumnus Lujendra Ojha and his team discovered proof of liquid water on the surface of Mars—a discovery confirmed by NASA in 2015. The University of Arizona receives more NASA grants annually than the next nine top NASA/JPL-Caltech-funded universities combined. As of March 2016, The University of Arizona’s Lunar and Planetary Laboratory is actively involved in ten spacecraft missions: Cassini VIMS; Grail; the HiRISE camera orbiting Mars; the Juno mission orbiting Jupiter; Lunar Reconnaissance Orbiter (LRO); Maven, which will explore Mars’ upper atmosphere and interactions with the sun; Solar Probe Plus, a historic mission into the Sun’s atmosphere for the first time; Rosetta’s VIRTIS; WISE; and OSIRIS-REx, the first U.S. sample-return mission to a near-earth asteroid, which launched on September 8, 2016.
NASA – GRAIL Flying in Formation (Artist’s Concept). Credit: NASA.
National Aeronautics Space Agency Juno at Jupiter.
NASA/Lunar Reconnaissance Orbiter.
NASA Parker Solar Probe Plus named to honor Pioneering Physicist Eugene Parker. The Johns Hopkins University Applied Physics Lab.
National Aeronautics and Space Administration Wise /NEOWISE Telescope.
The University of Arizona students have been selected as Truman, Rhodes, Goldwater, and Fulbright Scholars. According to The Chronicle of Higher Education, UArizona is among the top 25 producers of Fulbright awards in the U.S.
The University of Arizona is a member of the Association of Universities for Research in Astronomy , a consortium of institutions pursuing research in astronomy. The association operates observatories and telescopes, notably Kitt Peak National Observatory just outside Tucson.
National Science Foundation NOIRLab National Optical Astronomy Observatory Kitt Peak National Observatory on Kitt Peak of the Quinlan Mountains in the Arizona-Sonoran Desert on the Tohono O’odham Nation, 88 kilometers (55 mi) west-southwest of Tucson, Arizona, Altitude 2,096 m (6,877 ft), annotated.
Led by Roger Angel, researchers in the Steward Observatory Mirror Lab at The University of Arizona are working in concert to build the world’s most advanced telescope. Known as the Giant Magellan Telescope (CL), it will produce images 10 times sharper than those from the Earth-orbiting Hubble Telescope.
Giant Magellan Telescope(CL) 21 meters, to be at the Carnegie Institution for Science’s NOIRLab NOAO Las Campanas Observatory(CL), some 115 km (71 mi) north-northeast of La Serena, Chile, over 2,500 m (8,200 ft) high.
GMT will ultimately cost $1 billion. Researchers from at least nine institutions are working to secure the funding for the project. The telescope will include seven 18-ton mirrors capable of providing clear images of volcanoes and riverbeds on Mars and mountains on the moon at a rate 40 times faster than the world’s current large telescopes. The mirrors of the Giant Magellan Telescope will be built at The University of Arizona and transported to a permanent mountaintop site in the Chilean Andes where the telescope will be constructed.
Reaching Mars in March 2006, the Mars Reconnaissance Orbiter contained the HiRISE camera, with Principal Investigator Alfred McEwen as the lead on the project. This National Aeronautics and Space Agency mission to Mars carrying the UArizona-designed camera is capturing the highest-resolution images of the planet ever seen. The journey of the orbiter was 300 million miles. In August 2007, The University of Arizona, under the charge of Scientist Peter Smith, led the Phoenix Mars Mission, the first mission completely controlled by a university. Reaching the planet’s surface in May 2008, the mission’s purpose was to improve knowledge of the Martian Arctic. The Arizona Radio Observatory , a part of The University of Arizona Department of Astronomy Steward Observatory , operates the Submillimeter Telescope on Mount Graham.
University of Arizona Radio Observatory at NOAO Kitt Peak National Observatory, AZ USA, U Arizona Department of Astronomy and Steward Observatory at altitude 2,096 m (6,877 ft).

U Arizona Steward Observatory at NSF’s NOIRLab NOAO Kitt Peak National Observatory in the Arizona-Sonoran Desert 88 kilometers 55 mi west-southwest of Tucson, Arizona in the Quinlan Mountains of the Tohono O’odham Nation, altitude 2,096 m (6,877 ft).
The National Science Foundation funded the iPlant Collaborative in 2008 with a $50 million grant. In 2013, iPlant Collaborative received a $50 million renewal grant. Rebranded in late 2015 as “CyVerse”, the collaborative cloud-based data management platform is moving beyond life sciences to provide cloud-computing access across all scientific disciplines.
In June 2011, the university announced it would assume full ownership of the Biosphere 2 scientific research facility in Oracle, Arizona, north of Tucson, effective July 1. Biosphere 2 was constructed by private developers (funded mainly by Texas businessman and philanthropist Ed Bass) with its first closed system experiment commencing in 1991. The university had been the official management partner of the facility for research purposes since 2007.
U Arizona mirror lab-Where else in the world can you find an astronomical observatory mirror lab under a football stadium?
University of Arizona’s Biosphere 2, located in the Sonoran desert. An entire ecosystem under a glass dome? Visit our campus, just once, and you’ll quickly understand why The University of Arizona is a university unlike any other.
University of Arizona Landscape Evolution Observatory at Biosphere 2.
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