. | . |
Billion-year-old lake deposit yields clues to Earth's ancient biosphere by Staff Writers Montreal, Canada (SPX) Jul 19, 2018
A sample of ancient oxygen, teased out of a 1.4 billion-year-old evaporative lake deposit in Ontario, provides fresh evidence of what the Earth's atmosphere and biosphere were like during the interval leading up to the emergence of animal life. The findings, published in the journal Nature, represent the oldest measurement of atmospheric oxygen isotopes by nearly a billion years. The results support previous research suggesting that oxygen levels in the air during this time in Earth history were a tiny fraction of what they are today due to a much less productive biosphere. "It has been suggested for many decades now that the composition of the atmosphere has significantly varied through time," says Peter Crockford, who led the study as a PhD student at McGill University. "We provide unambiguous evidence that it was indeed much different 1.4 billion years ago." The study provides the oldest gauge yet of what earth scientists refer to as "primary production," in which micro-organisms at the base of the food chain - algae, cyanobacteria, and the like - produce organic matter from carbon dioxide and pour oxygen into the air.
A smaller biosphere "This means that the size of the global biosphere had to be smaller, and likely just didn't yield enough food - organic carbon - to support a lot of complex macroscopic life," says Wing, now an associate professor of geological sciences at University of Colorado at Boulder. To come up with these findings, Crockford teamed up with colleagues from Yale University, University of California Riverside, and Lakehead University in Thunder Bay, Ontario, who had collected pristine samples of ancient salts, known as sulfates, found in a sedimentary rock formation north of Lake Superior. Crockford shuttled the samples to Louisiana State University, where he worked closely with co-authors Huiming Bao, Justin Hayles, and Yongbo Peng, whose lab is one of a handful in the world using a specialized mass-spectrometry technique capable of probing such materials for rare oxygen isotopes within sulfates. The work also sheds new light on a stretch of Earth's history known as the "boring billion" because it yielded little apparent biological or environmental change. "Subdued primary productivity during the mid-Proterozoic era - roughly 2 billion to 800 million years ago - has long been implied, but no hard data had been generated to lend strong support to this idea," notes Galen Halverson, a co-author of the study and associate professor of earth and planetary sciences at McGill. That left open the possibility that there was another explanation for why the middle Proterozoic ocean was so uninteresting, in terms of the production and deposit of organic carbon." Crockford's data "provide the direct evidence that this boring carbon cycle was due to low primary productivity."
Exoplanet clues "For most of Earth history our planet was populated with microbes, and projecting into the future they will likely be the stewards of the planet long after we are gone," says Crockford, now a postdoctoral researcher at Princeton University and Israel's Weizmann Institute of Science. "Understanding the environments they shape not only informs us of our own past and how we got here, but also provides clues to what we might find if we discover an inhabited exoplanet."
Climate change is making night-shining clouds more visible Washington DC (SPX) Jul 03, 2018 Increased water vapor in Earth's atmosphere due to human activities is making shimmering high-altitude clouds more visible, a new study finds. The results suggest these strange but increasingly common clouds seen only on summer nights are an indicator of human-caused climate change, according to the study's authors. Noctilucent, or night-shining, clouds are the highest clouds in Earth's atmosphere. They form in the middle atmosphere, or mesosphere, roughly 80 kilometers (50 miles) above Earth's su ... read more
|
|
The content herein, unless otherwise known to be public domain, are Copyright 1995-2024 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. General Data Protection Regulation (GDPR) Statement Our advertisers use various cookies and the like to deliver the best ad banner available at one time. All network advertising suppliers have GDPR policies (Legitimate Interest) that conform with EU regulations for data collection. By using our websites you consent to cookie based advertising. If you do not agree with this then you must stop using the websites from May 25, 2018. Privacy Statement. Additional information can be found here at About Us. |