Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Plankton key to origin of Earth's first breathable atmosphere

22.02.2011
Researchers studying the origin of Earth's first breathable atmosphere have zeroed in on the major role played by some very unassuming creatures: plankton.

In a paper to appear in the online Early Edition of the Proceedings of the National Academy of Sciences (PNAS), Ohio State University researcher Matthew Saltzman and his colleagues show how plankton provided a critical link between the atmosphere and chemical isotopes stored in rocks 500 million years ago.

This work builds on the team's earlier discovery that upheavals in the earth's crust initiated a kind of reverse-greenhouse effect 500 million years ago that cooled the world's oceans, spawned giant plankton blooms, and sent a burst of oxygen into the atmosphere.

The new study has revealed details as to how oxygen came to vanish from Earth's ancient atmosphere during the Cambrian Period, only to return at higher levels than ever before.

It also hints at how, after mass extinctions, the returning oxygen allowed enormous amounts of new life to flourish.

Saltzman and his team were able to quantify how much oxygen was released into the atmosphere at the time, and directly link the amount of sulfur in the ancient oceans with atmospheric oxygen and carbon dioxide.

The result is a clearer picture of life on Earth in a time of extreme turmoil.

"We know that oxygen levels in the ocean dropped dramatically [a condition called anoxia] during the Cambrian, and that coincides with the time of a global extinction," said Saltzman, associate professor of earth sciences at Ohio State.

In a paper in the journal Nature just last month, the same researchers presented the first geochemical evidence that the anoxia spread even to the world's shallow waters.

"We still don't know why the anoxia spread all over the world. We may never know," Saltzman said. "But there have been many other extinction events in Earth's history, and with the exception of those caused by meteor impacts, others likely share elements of this one – changes in the balance of oxygen and carbon dioxide in the atmosphere and oceans."

"By getting a handle on what was happening back then, we may improve our understanding of what's happening to the atmosphere now."

Something enabled oxygen to re-enter the oceans and the atmosphere 500 million years ago, and the study suggests that the tiny plant and animal life forms known as plankton were key.

Plankton may be at the bottom our food chain today, but back then, they ruled the planet. There was no life on land at all. And aside from an abundance of trilobites, life in the oceans was not very diverse.

Not diverse, that is, until a geologic event that scientists call the Steptoean Positive Carbon Isotope Excursion (SPICE) occurred. In previous work, Saltzman and his collaborators showed that the SPICE event was caused by the burial of huge quantities of organic matter in ocean sediments, which pulled carbon dioxide from the atmosphere and released oxygen.

The more oxygen plankton encounter in their cells, the more selective they become for the light isotope of carbon in carbon dioxide, and absorb it into their bodies.

By studying isotopes in fossilized plankton contained in rocks found in the central United States, the Australian outback, and China, the researchers determined that the SPICE event happened around the same time as an explosion of plankton diversity known as the "plankton revolution."

"The amount of oxygen rebounded, and so did the diversity of life," Saltzman explained.

Other researchers have tried to gauge how much oxygen was in the air during the Cambrian, but their estimates have varied widely, from a few percent to as much as 15-20 percent.

If the higher estimates were correct, then the SPICE event would have boosted oxygen content to greater than 30 percent – or almost 50 percent richer than today's standard of 21 percent.

This study has provided a new perspective on the matter.

"We were able to bring together independent lines of evidence that showed that if the total oxygen content was around 5-10 percent before the SPICE, then it rose to just above modern levels for the first time after the SPICE," Saltzman said.

The study has some relevance to modern geoengineering. Scientists have begun to investigate what we can do to forestall climate change, and altering the chemistry of the oceans could help remove carbon dioxide and restore balance to the atmosphere. The ancient and humble plankton would be a necessary part of that equation, he added.

"When it comes to ancient life, they don't sound as exciting as dinosaurs, but the plankton are critical to this story."

Saltzman's coauthors on the PNAS paper include Seth Young of Indiana University; Lee Kump of Pennsylvania State University; Benjamin Gill of the University of California, Riverside, and Harvard University; Timothy Lyons, also of the University of California, Riverside; and Bruce Runnegar of the University of California, Los Angeles. Additional coauthors on the Nature paper included Andrew Knoll of Harvard University.

The National Science Foundation's Geobiology and Low-Temperature Geochemistry Program funded this research.

Contact: Matthew Saltzman, (614) 292-0481; Saltzman.11@osu.edu
Written by Pam Frost Gorder, (614) 292-9475; Gorder.1@osu.edu

Matthew Saltzman | EurekAlert!
Further information:
http://www.osu.edu

More articles from Earth Sciences:

nachricht A close-up look at an uncommon underwater eruption
11.01.2018 | Woods Hole Oceanographic Institution

nachricht Environmental history told by sludge: Global warming lets the dead zones in the Black Sea grow
10.01.2018 | Leibniz-Institut für Ostseeforschung Warnemünde

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...

Im Focus: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

Im Focus: Room-temperature multiferroic thin films and their properties

Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.

Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...

Im Focus: A thermometer for the oceans

Measurement of noble gases in Antarctic ice cores

The oceans are the largest global heat reservoir. As a result of man-made global warming, the temperature in the global climate system increases; around 90% of...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

 
Latest News

Novel 3-D printing technique yields high-performance composites

16.01.2018 | Materials Sciences

New application for acoustics helps estimate marine life populations

16.01.2018 | Life Sciences

Fast-tracking T cell therapies with immune-mimicking biomaterials

16.01.2018 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>