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The findings, published in the journal Nature represent the oldest measurement of isotopes of atmospheric oxygen by nearly a billion years. The findings support previous research suggesting that oxygen levels in the air during this period in the Earth 's history were a tiny fraction of what they are today. because of a much less productive biosphere.
"It has been suggested for several decades Peter Crockford, who led the study as a Ph.D. student at McGill University, said that the atmosphere has changed a lot over time. "We provide unambiguous evidence that it was actually very different 1.4 billion years ago."
The study provides the oldest gauge of what scientists call "primary production," in which the microorganisms at the base of the food chain – algae, cyanobacteria, and others – produce matter. organic from carbon dioxide.
A Smaller Biosphere
"This study shows that primary production, 1.4 billion years ago, was far less important than today. "says co-author Boswell Wing, who oversaw Crockford's work at McGill. "This means that the size of the global biosphere has to be smaller and probably does not produce enough food – organic carbon – to support a complex macroscopic life," says Wing, now an badociate professor of geological sciences at the university. . Crockford teamed up with colleagues from Yale University, the University of California at Riverside, and Lakehead University of Thunder Bay, Ontario, who had collected immaculate samples of ancient salts , known as sulphates. , found in a sedimentary rock formation north of Lake Superior. Crockford transported the samples to Louisiana State University, where he worked closely with co-authors Huiming Bao, Justin Hayles and Yongbo Peng, whose laboratory is one of the few in the world to use a specialized spectrometry technique mbad capable of probing such materials.
The book also sheds new light on a stretch of the Earth's history known as the "annoying billion" because it has produced little apparent biological or environmental changes.
"Moderate primary productivity in the middle of the Proterozoic It has long been implicit, there are about 2 billion to 800 million years, but no solid data has been generated to support this idea, "notes Galen Halverson, co-author of the study and badociate professor of science at McGill. "This left open the possibility that there was another explanation for which the average Proterozoic ocean was so uninteresting, in terms of organic carbon production and deposition." Crockford's data "provide direct evidence that this carbon cycle was boring."
Exoplanet clues
The findings could also help inform astronomers of the search for life outside of our own solar system.
"For most of the Earth's history, our planet was peopled with microbes, and projecting themselves into the future they will probably be the guardians of the planet long after we let's be gone, "says Crockford, now a postdoctoral researcher at Princeton University and Weizmann Institute of Science in Israel. "Understanding the environments that they shape not only informs us of our own past and how we arrived here, but also provides clues to what we might find if we discover an inhabited exoplanet."
MCGILL UNIVERSITY [19659002] Header Image – Lake superior – Image credit: Kevstan
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