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A sample of old oxygen, collected from a 1.4 billion year old evaporative lake deposit in Ontario, provides new evidence of the Earth 's atmosphere and biosphere during the 1980s. Interval leading to the emergence of animal life. 19659002] The results, 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 unequivocal evidence that it was indeed 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 the like – produce organic matter from carbon dioxide and release oxygen in the air.
A Lesser Biosphere
"This study shows that primary production was much less than today," says the co – Principal author, Boswell Wing, who oversaw Crockford's work at McGill. "This means that the size of the world biosphere has to be smaller and that it probably does not produce enough food – organic carbon – to support a complex macroscopic life," says Wing, now an badociate professor of geological sciences. Crockford teamed up with colleagues from Yale University, the University of California at Riverside, and Lakehead University in Thunder Bay, Ontario, who had collected pure samples of ancient salts , known at the University of Colorado at Boulder
. in the form of 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 part 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 the Earth. and planetary sciences at McGill. "This left open the possibility that there was another explanation why the average Proterozoic ocean was so uninteresting, in terms of organic carbon production and deposition." Crockford's data "provides direct evidence that this annoying carbon cycle was due to low primary productivity."
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 has been populated with microbes, and planning into the future they will likely be the guardians of the planet long after we're gone," says Crockford, now postdoctoral researcher at Princeton University and Israel. Weizmann Institute of Science. "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."
