Free Newsletters - Space - Defense - Environment - Energy - Solar - Nuclear
..
. 24/7 Space News .




EARLY EARTH
The ups and downs of early atmospheric oxygen
by Staff Writers
Riverside CA (SPX) Feb 24, 2014


This photo shows one-billion-year-old weathering profiles from Michigan. Ancient soils like these provide evidence for low atmospheric oxygen levels through much of Earth's history. Image courtesy Noah Planavsky.

A team of biogeochemists at the University of California, Riverside, give us a nontraditional way of thinking about the earliest accumulation of oxygen in the atmosphere, arguably the most important biological event in Earth history. A general consensus asserts that appreciable oxygen first accumulated in Earth's atmosphere around 2.3 billion years ago during the so-called Great Oxidation Event (GOE).

However, a new picture is emerging: Oxygen production by photosynthetic cyanobacteria may have initiated as early as 3 billion years ago, with oxygen concentrations in the atmosphere potentially rising and falling episodically over many hundreds of millions of years, reflecting the balance between its varying photosynthetic production and its consumption through reaction with reduced compounds such as hydrogen gas.

"There is a growing body of data that points to oxygen production and accumulation in the ocean and atmosphere long before the GOE," said Timothy W. Lyons, a professor of biogeochemistry in the Department of Earth Sciences and the lead author of the comprehensive synthesis of more than a decade's worth of study within and outside his research group.

Lyons and his coauthors, Christopher T. Reinhard and Noah J. Planavsky, both former UCR graduate students, note that once oxygen finally established a strong foothold in the atmosphere starting about 2.3 billion years ago it likely rose to high concentrations, potentially even levels like those seen today. Then, for reasons not well understood, the bottom fell out, oxygen plummeted to a tiny fraction of today's level, and the ocean remained mostly oxygen free for more than a billion years.

"This period of extended low oxygen spanning from roughly 2 to less than 1 billion years ago was a time of remarkable chemical stability in the ocean and atmosphere," Lyons said.

His research team envisions a series of interacting processes, or feedbacks, that maintained oxygen at very low levels principally by modulating the availability of life-sustaining nutrients in the ocean and thus oxygen-producing photosynthetic activity.

"We suggest that oxygen was much lower than previously thought during this important middle chapter in Earth history, which likely explains the low abundances and diversity of eukaryotic organisms and the absence of animals," Lyons said.

The late Proterozoic-the time period beginning less than a billion years ago following this remarkable chapter of sustained low levels of oxygen-was strikingly different, marked by extreme climatic events manifest in global-scale glaciation, indications of at least intervals of modern-like oxygen abundances, and the emergence and diversification of the earliest animals.

Lyons notes that the factors controlling the rise of animals are under close scrutiny, including challenges to the long-held view that a major rise in atmospheric oxygen concentrations triggered the event.

"Despite the new ideas about animal origins, we suspect that oxygen played a major if not dominant role in the timing of that rise and, in particular, in the subsequent emergence of complex ecologies for animal life on and within the sediment, predator-prey relationships, and large bodies" said Lyons. "But, again, feedbacks always rule the day. Environmental change drives evolution, and steps in the progression of life change the environment."

No single factor is likely to be the whole story, and there is much more to be written in the tale. Lyons and coauthors, along with research groups from around world over, are focusing current efforts on the timing and drivers of oxygenation in the late Proterozoic, favoring a combination of global-scale mountain building, evolutionary controls on the way carbon is cycled in the biosphere, and concomitant climate events.

"We are faced with a lot of chicken-and-egg questions when it comes to unraveling the timing and sequence of oxygenation of the ocean and atmosphere," Lyons said. "But now, armed with new and better data, more sophisticated numerical simulations, and highly integrated investigations in the lab and the field, Earth's oxygenation history seems much longer and more dynamic than envisioned before, and we are getting closer to understanding the mechanisms behind such change."

The paper appears in Nature on Feb. 19. Reinhard is a postdoctoral fellow at the California Institute of Technology and will join the faculty of the Georgia Institute of Technology as an assistant professor later this year. Planavsky is an assistant professor at Yale University.

.


Related Links
University of California - Riverside
Explore The Early Earth at TerraDaily.com






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News





EARLY EARTH
Evolution stuck in slime for a billion years
Hobart, Australia (SPX) Feb 24, 2014
Tasmanian researchers have revealed ancient conditions that almost ended life on Earth, using a new technique they developed to hunt for mineral deposits. The first life developed in the ancient oceans around 3.6 billion years ago, but then nothing much happened. Life remained as little more than a layer of slime for a billion years. Suddenly, 550 million years ago, evolution burst back in ... read more


EARLY EARTH
China Focus: Uneasy rest begins for China's troubled Yutu rover

Is Yutu Stuck?

Japan's Pocari Sweat bound for the moon: maker

Lunar ownership laws: a future necessity?

EARLY EARTH
NASA Mars Orbiter Views Opportunity Rover on Ridge

Curiosity Adds Reverse Driving for Wheel Protection

Curiosity Drives On After Crossing Martian Dune

The World Above and Beyond

EARLY EARTH
DARPA Open Catalog Makes Agency-Sponsored Software and Publications Available to All

Orion Underway Recovery Testing Begins off the Coast of California

Inside astronaut Alexander's head

NASA Welcomes University Participants to Develop Science Payloads

EARLY EARTH
No Call for Yutu

What's up, Yutu

China's Jade Rabbit rover comes 'back to life'

Yutu Awakes

EARLY EARTH
Space suit leak happened before, NASA admits

NASA Seeks US Industry Feedback on Options for Future ISS Cargo Services

NASA, International Space Station Partners Announce Future Crew Members

Andrews Space Cargo Module Power Unit Provides Power For Payloads Bound For ISS

EARLY EARTH
'Mission of Firsts' Showcased New Range-Safety Technology at NASA Wallops

First Copernicus satellite at launch site

Arianespace to launch OPTSAT 3000 and VENuS satellites

Lighter engines a headache for satellite launcher Ariane

EARLY EARTH
NASA cries planetary 'bonanza' with 715 new worlds

Detection of Water Vapor in the Atmosphere of a Hot Jupiter

ESA selects planet-hunting PLATO mission

Rife with hype, exoplanet study needs patience and refinement

EARLY EARTH
EIAST showcases DubaiSat-2 results, plans for KhalifaSat at space conference in Singapore

A New Way to Create Porous Materials

USAF reveals 'neighborhood watch' satellite program

UT Dallas-led team makes powerful muscles from fishing line and sewing thread




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - 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. 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. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.