NSF: Evidence points to widespread loss of ocean oxygen by 2030s .- La evidencia apunta a la pérdida generalizada de oxígeno del océano por la década de 2030....

Hola amigos: A VUELO DE UN QUINDE EL BLOG., hemos recibido información de la Fundación Nacional de Ciencias de Los Estados Unidos, sobre las evidencias de la pérdida de oxígeno en los océanos en el década del 2,030, nos dice: "El cambio climático ha provocado una caída en la cantidad de oxígeno disuelto en los océanos en algunas partes del mundo, y esos efectos debería ser evidente a través de grandes partes del océano entre 2030 y 2040, según un nuevo estudio dirigido por investigadores del Centro Nacional de Investigación atmosférica (NCAR) en Boulder, Colorado.Los científicos espera que el calentamiento global a los océanos de la savia de oxígeno, dejando de pescado, cangrejos, calamares, estrellas de mar y otras especies marinas luchando por respirar. Pero habían encontrado dificultades para determinar si esta fuga de oxígeno anticipado ya estaba teniendo un efecto notable."La pérdida de oxígeno en los océanos es uno de los efectos secundarios graves de calentamiento de la atmósfera, y una amenaza para la vida marina", dijo el científico del NCAR Mateo largo, autor principal del estudio. "Dado que las concentraciones de oxígeno en el océano varía naturalmente dependiendo de las variaciones en los vientos y la temperatura en la superficie, que ha sido un reto para atribuir cualquier desoxigenación al cambio climático. Este nuevo estudio nos dice cuándo podemos esperar el efecto del cambio climático para abrumar a la variabilidad natural ".

More information.........

http://www.nsf.gov/news/news_summ.jsp?cntn_id=138396&WT.mc_id=USNSF_51&WT.mc_ev=click

Deoxygenation due to climate change threatens marine life

Marine life moves much more slowly in a low-oxygen ocean. Credit and Larger Version

April 27, 2016

Climate change has caused a drop in the amount of oxygen dissolved in the oceans in some parts of the world, and those effects should become evident across large parts of the ocean between 2030 and 2040, according to a new study led by researchers at the National Center for Atmospheric Research (NCAR) in Boulder, Colorado.

Scientists expected a warming climate to sap oceans of oxygen, leaving fish, crabs, squid, sea stars, and other marine life struggling to breathe. But they had encountered difficulties in determining whether this anticipated oxygen drain was already having a noticeable effect.

"Loss of oxygen in the oceans is one of the serious side effects of a warming atmosphere, and a major threat to marine life," said NCAR scientist Matthew Long, lead author of the study. “Since oxygen concentrations in the ocean naturally vary depending on variations in winds and temperature at the surface, it's been challenging to attribute any deoxygenation to climate change. This new study tells us when we can expect the effect from climate change to overwhelm the natural variability."

The study is published in the American Geophysical Union journal Global Biogeochemical Cycles. The research was funded by the National Science Foundation (NSF).

 

Cutting through the natural variability

 

The entire ocean -- from the depths to the shallows -- gets its oxygen supply from the surface, either from the atmosphere or from phytoplankton, which release oxygen into the water through photosynthesis.

Warming surface waters, however, absorb less oxygen. And, in a double whammy, the absorbed oxygen has a more difficult time traveling deeper into the ocean. That's because as water heats up, it expands, becoming lighter than the water below it and less likely to sink.

Thanks to natural warming and cooling, oxygen concentrations at the sea's surface change constantly -- and deeper in the ocean, those changes can linger for years or decades.

For example, an exceptionally cold winter in the North Pacific would allow the ocean surface to soak up a large amount of oxygen. Thanks to the natural circulation pattern, that oxygen would then be carried deeper into the ocean, where it might still be detectable years later as it travels along its flow path.

On the flip side, unusually hot weather could lead to "dead zones" in the ocean, where fish and other marine life cannot survive.

To cut through this natural variability and investigate the impact of climate change, the research team -- including Curtis Deutsch of the University of Washington and Taka Ito of Georgia Tech -- relied on the NCAR-based Community Earth System Model, which is funded by NSF and the U.S. Department of Energy.

“This study shows how far comprehensive Earth System Models have come in the effort to quantify, along with relatively sparse observations, large-scale changes in oxygen in the oceans due to both natural variability and climate change,” said Eric Itsweire, program director in NSF's Division of Ocean Sciences.

The scientists used output from a project that ran the model more than two dozen times for the years 1920 to 2100. Each individual run started with miniscule variations in air temperature. As the model runs progressed, those tiny differences grew and expanded, producing a set of climate simulations useful for studying questions about variability and change.

Using the simulations to study dissolved oxygen gave the researchers guidance on the degree to which concentrations may have varied naturally in the past. With this information, they could determine when ocean deoxygenation due to climate change is likely to become more severe than at any point in the modeled historic range.

The researchers found they could already detect deoxygenation caused by climate change in the southern Indian Ocean and parts of the eastern tropical Pacific and Atlantic basins.

They also determined that more widespread detection of deoxygenation caused by climate change would be possible between 2030 and 2040.

However, in some parts of the ocean, including areas off the east coasts of Africa, Australia, and Southeast Asia, deoxygenation caused by climate change would not become evident even by 2100.

 

Detecting a global pattern

 

The researchers also created a visual way to distinguish between deoxygenation caused by natural processes and deoxygenation caused by climate change.

Using the same model dataset, the scientists created maps of oxygen levels in the ocean, showing which waters were oxygen-rich and which were oxygen-poor. They found they could distinguish between oxygenation patterns caused by natural weather phenomena and the pattern caused by climate change.

The climate change pattern also became evident in the model runs around 2030, adding confidence to the conclusion that widespread deoxygenation due to climate change will become detectable around that time.

The maps could also be useful resources for deciding where to place instruments to monitor ocean oxygen levels in the future to get the best picture of climate change effects. Currently, ocean oxygen measurements are relatively sparse.

"We need comprehensive and sustained observations of what's going on in the oceans to compare with what we're learning from our models, and to understand the full effect of a changing climate," Long said.

-NSF-

Media Contacts Cheryl Dybas, NSF, (703) 292-7734, cdybas@nsf.gov
David Hosansky, NCAR, (303) 497-8611, hosansky@ucar.edu

The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering. In fiscal year (FY) 2016, its budget is $7.5 billion. NSF funds reach all 50 states through grants to nearly 2,000 colleges, universities and other institutions. Each year, NSF receives more than 48,000 competitive proposals for funding and makes about 12,000 new funding awards. NSF also awards about $626 million in professional and service contracts yearly.

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By the 2030s, declining oxygen levels will likely be evident in many of the world's oceans.
Credit and Larger Version

How will species such as crabs fare in low oxygen seas? Scientists are working to find answers.
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Dungeness crabs washed up on a beach in Oregon after suffocating in low-oxygen waters.
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In ocean waters with less oxygen, fish kills are common.
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Declining cod stocks may be further threatened by waters with low oxygen.
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NASA : Chandra Celebrates 15th Anniversary: Supernova Remnant G292.0+1.8

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Chandra Celebrates 15th Anniversary: Supernova Remnant G292.0+1.8

At a distance of about 20,000 light years, G292.0+1.8 is one of only three supernova remnants in the Milky Way known to contain large amounts of oxygen. These oxygen-rich supernovas are of great interest to astronomers because they are one of the primary sources of the heavy elements (that is, everything other than hydrogen and helium) necessary to form planets and people. The X-ray image from Chandra shows a rapidly expanding, intricately structured, debris field that contains, along with oxygen (yellow and orange), other elements such as magnesium (green) and silicon and sulfur (blue) that were forged in the star before it exploded.

Image credit: NASA/CXC/SAO

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nsf.gov - National Science Foundation - Harvesting sunlight to help feed and fuel the world

Three U.S./U.K. funded projects have been awarded a total of almost $9 million in additional funding to continue research projects aimed at improving the efficiency of photosynthesis

Scientists are using novel methods to explore potential new ways to boost photosynthetic efficiency. Credit and Larger Version

May 30, 2014

Three research teams--each comprised of scientists from the United States and the United Kingdom--have been awarded a second round of funding to continue research on news ways to improve the efficiency of photosynthesis.

 

Societal benefits

The ultimate goal of this potentially high-impact research is to develop methods to increase yields of important crops that are harvested for food and sustainable biofuels. But if this research is successful, it may also be used to support reforestation efforts and efforts to increase the productivity of trees for the manufacture of wood and paper and thousands of other products that are derived from wood and chemicals extracted from trees. Another reason why photosynthesis is an important research topic: It has made the Earth hospitable for life by generating food and oxygen.

The second round of funding to the three refunded research teams is from the U.S.'s National Science Foundation (NSF) and the U.K.'s Biotechnology and Biological Sciences Research Council (BBSRC). This funding will total almost $9 million over three years. Each team is receiving additional funding because of the significant progress it achieved via its initial round of funding, which was also jointly awarded by NSF and the BBSRC in 2011.

 

Why and how can the efficiency of photosynthesis be increased?

A photosynthesizing organism uses sunlight and carbon dioxide to produce sugars that fuel the organism and release oxygen. But photosynthesis is a relatively inefficient process, usually capturing only about 5 percent of available energy, depending on how efficiency is measured. Nevertheless, some species of plants, algae and bacteria have evolved efficiency-boosting mechanisms that reduce energy losses or enhance carbon dioxide delivery to cells during photosynthesis.

Each of the three funded research teams is working, in a new and unique way, to improve, combine or engineer these types of efficiency-boosting mechanisms, so they may eventually be conferred on important crops that provide food or sustainable biofuels.

Scientists have long sought ways to increase the efficiency of photosynthesis but without, thus far, producing significant breakthroughs. The potentially transformational methods currently being pursued by the three funded teams were developed during an "Ideas Lab"--a workshop held in 2010 that was specially designed to generate innovative, potentially transformative research projects that might open longstanding bottlenecks to photosynthesis research.

If successful in helping to open such bottlenecks and generate ways to improve photosynthetic efficiency, any of the three re-funded research projects could provide critical support for efforts to address food and fuel challenges currently created by increasing human populations and other factors.

John Wingfield, NSF's assistant director for the Directorate of Biological Sciences, said, "Photosynthesis captures abundant and free solar energy and generates food and oxygen for the planet. Emerging technologies, like synthetic biology, are used in these potentially transformative projects to address the long-standing quest to increase efficiency of photosynthesis."

 

The three refunded projects:

1. Plug-and-play photosynthesis led by Anne Jones of Arizona State University: Some single-celled microbes capture solar energy and convert it to fuel for self-replication. Plug-and-play photosynthesis aims to distribute the capture and conversion of energy to two environments, so that each environment can be optimized for maximum efficiency for its role.

The plug-and-play team's overall goal is to capture unused energy, which would otherwise be dissipated, from a light-capturing photosynthetic cell--and transfer it to a second cell for fuel production. One way to carry out this energy transfer is to repurpose bacterial nanowires, which are tiny, electrically conductive wires that are present in some bacteria for reasons that are not yet completely understood.

These wires will be bioengineered to form an electrical bridge between light-capturing cells and fuel-producing cells--so that the wires will conduct energy from the former to the latter. To advance this project the plug-and-play team, together with other investigators, have corrected a false, but long accepted, mischaracterization of the biochemical composition of the bacterial nanowires and have thereby provided a new starting point for further study and engineering.

The research team is also working to develop another approach to intercellular energy transfer by creating new chemical pathways that would divert energy from the bacterial light-capturing cell to a designed biofuel-producing cell. The plug-and-play team has advanced this effort by developing a bioelectrochemical device that measures energy production by bacterial light-capturing cells.

 

2. Multi-Level Approaches for Generating Carbon Dioxide (MAGIC) led by John Golbeck of Pennsylvania State University: MAGIC is aimed at engineering a light-driven carbon dioxide pump that will increase the availability of carbon dioxide to an enzyme that promotes photosynthesis and will thereby increase photosynthetic efficiency.

To advance this effort, the team has, through genetic engineering, repurposed a light-sensitive protein, called halorhodopsin, which is found in a one-celled microbe called Natronomonas pharaonis; this protein helps the microbe maintain the correct chemical balance by pumping chloride into it. But the reengineered form of this protein instead pumps carbon dioxide, which is present as bicarbonate, into cells. To evaluate its pump's effectiveness, the team incorporated its light-driven bicarbonate pump into an artificial vesicle. This vesicle contains a dye whose brightness is proportional to carbon dioxide levels in the vesicle's interior--and therefore provides important information about the pump's usefulness. The team is preparing to incorporate its pump into plant cells to determine if resulting increases in the availability of carbon dioxide to plant cells will increase their growth.

 

3. Combining Algal and Plant Photosynthesis (CAPP) led by Martin Jonikas of Stanford University: Chlamydomonas, a unicellular algae, has a pyrenoid--a ball-shaped structure that helps the algae assimilate carbon to improve its photosynthetic efficiency. CAPP is aiming to, for the first time, transplant the algal pyrenoid and its associated components into higher plants--with hopes of improving these plants' photosynthetic efficiency and thus their productivity.

So far, the team has identified novel components of the pyrenoid. It has also made progress towards the development of a protein-based sensor that will be used to compare levels of bicarbonate in several cellular compartments in algae. This sensor will be used to help explain the algae's carbon concentrating mechanism and help evaluate the pyrenoid's effectiveness after it has been transplanted into higher plants.

 

Improving on nature

Jackie Hunter, BBSRC chief executive said, "Nature barely skims the surface when it comes to photosynthesis and making use of the sun's energy. There is huge room for improvement and these research projects are taking steps to help us to unlock hidden potential that could benefit us all. Using the sun's energy more efficiently means a greater potential to produce fuel, food, fibers, useful chemicals and much more."

Gregory Warr, an NSF program director, said, "These projects, if successful, could transform the way we generate the fuel, food, clothing and shelter that plants and microbes provide to us."

-NSF-

Media Contacts Lily Whiteman, National Science Foundation, (703) 292-8310,

lwhitema@nsf.gov
Robert Dawson, U.K. Biotechnology and Biological Sciences Research Council, 01793 413 204, Robert.Dawson@bbsrc.ac.uk

Program Contacts Gregory Warr, National Science Foundation, (703) 292-8284,

 gwarr@nsf.gov
Kent Dearn Chapman, National Science Foundation, (703) 292-7879,

 kchapman@nsf.gov

The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering. In fiscal year (FY) 2014, its budget is $7.2 billion. NSF funds reach all 50 states through grants to nearly 2,000 colleges, universities and other institutions. Each year, NSF receives about 50,000 competitive requests for funding, and makes about 11,500 new funding awards. NSF also awards about $593 million in professional and service contracts yearly.

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Plug-and-play will separate processes into two environments connected by conductive nanowires.
Credit and Larger Version

The MAGIC team's pump will transport into cells bicarbonate (HCO3-) that will be converted into CO2.
Credit and Larger Version

CAPP: An algea pyrenoid appears blue and its chloroplast, a photosynthesizing unit, appears green.
Credit and Larger Versión
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NASA : NASA Astronauts Will Breathe Easier With New Oxygen Recovery Systems

ISS Air Revittilization System rack represents the state of the art in spacecraft oxygen recovery technology

Image Credit:

NASA

For NASA's long-duration human spaceflight missions, travelers will need to recycle as much breathable oxygen in their spacecraft environments, as possible. To turn that need into a reality, NASA is seeking proposals for lightweight, safe, efficient and reliable systems for regenerating oxygen on future human exploration missions.

The first of two phases of this new NASA solicitation will consist of a detailed design, development, fabrication, and testing of an advanced oxygen recovery technology. Under a two year Phase II contract, the proposer then will develop a prototype hardware system, capable of an oxygen recovery rate of at least 75 percent.

"Lengthy spaceflight missions in Earth's orbit and beyond must have life support systems that are more self-sufficient and reliable," said Michael Gazarik, associate administrator for Space Technology at NASA Headquarters in Washington. "The spacecraft life support system technologies for this proposal must significantly improve the rate of oxygen recovery while achieving high degrees reliability. NASA and its partners will need to develop new technologies to 'close' the atmosphere revitalization loop."

In addition to improving the oxygen recovery rate, the new systems must reduce mass required or take up less space and reduce power consumption. NASA's goal is to award technology development efforts that will increase the oxygen recovery rate to at least 75 percent without adversely impacting other design requirements.

The agency's Game Changing Development Program will accept proposals from NASA centers, other government agencies, federally funded research and development centers, educational institutions, industry and nonprofit organizations. NASA expects to make approximately six Phase I awards, ranging in value up to $750,000.

The Advanced Oxygen Recovery for Spacecraft Life Support Systems Appendix is part of the Space Technology Mission Directorate Game Changing Development Program NASA Research Announcement, "Space Technology Research, Development, Demonstration, and Infusion 2014" for high priority technology areas of interest to NASA.

The SpaceTech-REDDI-2014 Advanced Oxygen Recovery for Spacecraft Life Support Systems Appendix is available through the NASA Solicitation and Proposal Integrated Review and Evaluation System website by going to "Solicitations" and then "Open Solicitations" at:

http://nspires.nasaprs.com/

NASA's Langley Research Center in Hampton, Va., manages the Game Changing Development Program for the agency's Space Technology Mission Directorate. NASA's Space Technology Mission Directorate remains committed to developing the critical technologies required to enable future exploration missions beyond low-Earth orbit. The directorate continues to solicit the help of the best and brightest minds in academia, industry, and government to drive innovation and enable solutions in a myriad of important technology thrust areas. These planned investments are addressing high priority challenges for achieving safe and affordable deep-space exploration.

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Astronomy: Small Planets Don't Need Stars With Heavy Metal Content To Form

Hi My Friends: A VUELO DE UN QUINDE EL BLOG., The formation of small worlds like Earth previously was thought to occur mostly around stars rich in heavy elements such as iron and silicon. However, new ground-based observations, combined with data collected by NASA's Kepler space telescope, shows small planets form around stars with a wide range of heavy element content and suggests they may be widespread in our galaxy. 

Small Planets Don't Need Stars With Heavy Metal Content To Form

 

 

WASHINGTON -- The formation of small worlds like Earth previously was thought to occur mostly around stars rich in heavy elements such as iron and silicon. However, new ground-based observations, combined with data collected by NASA's Kepler space telescope, shows small planets form around stars with a wide range of heavy element content and suggests they may be widespread in our galaxy.

A research team led by Lars A. Buchhave, an astrophysicist at the Niels Bohr Institute and the Centre for Star and Planet Formation at the University of Copenhagen, studied the elemental composition of more than 150 stars harboring 226 planet candidates smaller than Neptune.

"I wanted to investigate whether small planets needed a special environment in order to form, like the giant gas planets, which we know preferentially develop in environments with a high content of heavy elements," said Buchhave. "This study shows that small planets do not discriminate and form around stars with a wide range of heavy metal content, including stars with only 25 percent of the sun's metallicity."
Astronomers refer to all chemical elements heavier than hydrogen and helium as metals. They define metallicity is the metal content of heavier elements in a star. Stars with a higher fraction of heavy elements than the sun are considered metal-rich. Stars with a lower fraction of heavy elements are considered metal-poor.

Planets are created disks of gas and dust around new stars. Planets like Earth are composed almost entirely of elements such as iron, oxygen, silicon and magnesium.

The metallicity of a star mirrors the metal content of the planet-forming disk. Astronomers have hypothesized that large quantities of heavy elements in the disk would lead to more efficient planet formation. It has long been noted that giant planets with short orbital periods tend to be associated with metal-rich stars.

Unlike gas giants, the occurrence of smaller planets is not strongly dependent on the heavy element content of their host stars. Planets up to four times the size of Earth can form around stars with a wide range of heavy element content, including stars with a lower metallicity than the sun. The findings are described in a new study published in the journal Nature.

"Kepler has identified thousands of planet candidates, making it possible to study big-picture questions like the one posed by Lars. Does nature require special environments to form Earth-size planets?" said Natalie Batalha, Kepler mission scientist at NASA's Ames Research Center at Moffett Field, Calif. "The data suggest that small planets may form around stars with a wide range of metallicities -- that nature is opportunistic and prolific, finding pathways we might otherwise have thought difficult."

The ground-based spectroscopic observations for this study were made at the Nordic Optical Telescope on La Palma in the Canary Islands; Fred Lawrence Whipple Observatory on Mt. Hopkins in Ariz.; McDonald Observatory at the University of Texas at Austin; and W.M. Keck Observatory atop Mauna Kea in Hawaii.

Launched in March 2009, Kepler searches for planets by continuously monitoring more than 150,000 stars, looking for telltale dips in their brightness caused by passing, or transiting, planets. At least three transits are required to verify a signal as a planet. Follow-up observations from ground-based telescopes are also needed to confirm a candidate as a planet.

Ames manages Kepler's ground system development, mission operations and science data analysis. NASA's Jet Propulsion Laboratory in Pasadena, Calif., managed the Kepler mission development.

Ball Aerospace & Technologies Corp. in Boulder, Colo., developed the Kepler flight system and supports mission operations with the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder.

The Space Telescope Science Institute in Baltimore archives hosts and distributes Kepler science data. Kepler is NASA's 10th Discovery Mission and is funded by NASA's Science Mission Directorate at the agency's headquarters in Washington.

For more information about the Kepler mission, visit:

 

http://www.nasa.gov/kepler

 

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text-only version of this release

 Small Planets Don't Need Stars with Heavy Metal Content to Form

 

 

MOFFETT FIELD, Calif. -- The formation of small worlds like Earth previously was thought to occur mostly around stars rich in heavy elements such as iron and silicon. However, new ground-based observations, combined with data collected by NASA's Kepler space telescope, shows small planets form around stars with a wide range of heavy element content and suggests they may be widespread in our galaxy.

A research team led by Lars A. Buchhave, an astrophysicist at the Niels Bohr Institute and the Centre for Star and Planet Formation at the University of Copenhagen, studied the elemental composition of more than 150 stars harboring 226 planet candidates smaller than Neptune.

"I wanted to investigate whether small planets needed a special environment in order to form, like the giant gas planets, which we know preferentially develop in environments with a high content of heavy elements," said Buchhave. "This study shows that small planets do not discriminate and form around stars with a wide range of heavy metal content, including stars with only 25 percent of the sun's metallicity."

Astronomers refer to all chemical elements heavier than hydrogen and helium as metals. They define metallicity as the metal content of heavier elements in a star. Stars with a higher fraction of heavy elements than the sun are considered metal-rich. Stars with a lower fraction of heavy elements are considered metal-poor.

Planets are created in disks of gas and dust around new stars. Planets like Earth are composed almost entirely of elements such as iron, oxygen, silicon and magnesium. The metallicity of a star mirrors the metal content of the planet-forming disk. Astronomers have hypothesized that large quantities of heavy elements in the disk would lead to more efficient planet formation. It has long been noted that giant planets with short orbital periods tend to be associated with metal-rich stars.

Unlike gas giants, the occurrence of smaller planets is not strongly dependent on the heavy element content of their host stars. Planets up to four times the size of Earth can form around stars with a wide range of heavy element content, including stars with a lower metallicity than the sun. The findings are described in a new study published in the journal Nature.

"Kepler has identified thousands of planet candidates, making it possible to study big-picture questions like the one posed by Lars. Does nature require special environments to form Earth-size planets?" said Natalie Batalha, Kepler mission scientist at NASA's Ames Research Center at Moffett Field, Calif. "The data suggest that small planets may form around stars with a wide range of metallicities -- that nature is opportunistic and prolific, finding pathways we might otherwise have thought difficult."

The ground-based spectroscopic observations for this study were made at the Nordic Optical Telescope on La Palma in the Canary Islands; Fred Lawrence Whipple Observatory on Mt. Hopkins in Ariz.; McDonald Observatory at the University of Texas at Austin; and W.M. Keck Observatory atop Mauna Kea in Hawaii.

Launched in March 2009, Kepler searches for planets by continuously monitoring more than 150,000 stars, looking for telltale dips in their brightness caused by passing, or transiting, planets. At least three transits are required to verify a signal as a planet. Follow-up observations from ground-based telescopes are also needed to confirm a candidate as a planet.

Ames manages Kepler's ground system development, mission operations and science data analysis. NASA's Jet Propulsion Laboratory in Pasadena, Calif., managed the Kepler mission development.

Ball Aerospace & Technologies Corp. in Boulder, Colo., developed the Kepler flight system and supports mission operations with the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder.

The Space Telescope Science Institute in Baltimore archives hosts and distributes Kepler science data. Kepler is NASA's 10th Discovery Mission and is funded by NASA's Science Mission Directorate at the agency's headquarters in Washington.

For more information about the Kepler mission, visit:

http://www.nasa.gov/kepler


The artist conception shows a newly formed star surrounded by a swirling protoplanetary disk of dust and gas. Debris coalesces to create rocky 'planetesimals' that collide and grow to eventually form planets. The results of this study show that small planets form around stars with a wide range of heavy element content suggesting that their existence might be widespread in the galaxy. Credit: University of Copenhagen/Lars Buchhave

 

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text-only version of this release

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Science: Path to Oxygen in Earth's Atmosphere: Long Series of Starts and Stops

Hi my Friends: A VUELO DE UN QUINDE EL BLOG., Rock cores from Northwest Russia provide new insights.Panorama of Russia's Imandra/Varzuga Greenstone Belt where FAR DEEP drilling took place.

Credit: Victor Melezhik, Geological Survey of Norway/University of Bergen

The appearance of oxygen in the Earth's atmosphere probably did not occur as a single event, but as a long series of starts and stops, according to geoscientists who investigated rock cores from the FAR DEEP project.
The Fennoscandia Arctic Russia - Drilling Early Earth Project--FAR DEEP--took place during the summer of 2007 near Murmansk in Northwest Russia.
The project, part of the International Continental Scientific Drilling Program, drilled a series of shallow, two-inch diameter cores and, by overlapping them, created a record of stone deposited during the Proterozoic Eon--2,500 million to 542 million years ago.
"We've always thought that oxygen came into the atmosphere really quickly during an event," said Lee Kump, a geoscientist at Penn State University.
"We are no longer looking for an event. Now we're looking for when and why oxygen became a stable part of the Earth's atmosphere."
The researchers report in this week's issue of the journal Science Express that evaluation of these cores, in comparison with cores from Gabon previously analyzed by others, supports the conclusion that the Great Oxidation Event, the appearance of free oxygen in Earth's atmosphere, played out over hundreds of millions of years. Kump is the lead author of the Science Express paper.
Oxygen levels gradually crossed the low atmospheric oxygen threshold for pyrite--an iron sulfur mineral--oxidation by 2,500 million years ago, and the loss of what scientists call mass-independently fractionated (MIF) sulfur by 2,400 million years ago.
Then oxygen levels rose at an ever-increasing rate through the Paleoproterozoic, achieving about one percent of the present atmospheric level.
"The definition of when an oxygen atmosphere occurred depends on which threshold you are looking for," said Kump. "It could be when pyrite becomes oxidized, when sulfur MIF disappears, or when deep crustal oxidation occurs."
When the MIF sulfur disappeared, the air on Earth was still not breathable by animal standards.
When red rocks containing iron oxides appeared 2,300 million years ago, the air was still unbreathable.
"At about one percent oxygen, the groundwater became strongly oxidized, making it possible for water seeping through rocks to oxidize organic materials," said Kump.
Initially, any oxygen in the atmosphere, produced by the photosynthesis of single-celled organisms, was used up when sulfur, iron and other elements oxidized.
When sufficient oxygen accumulated in the atmosphere, it permeated the groundwater and began oxidizing buried organic material, oxidizing carbon to create carbon dioxide.
"Insights into Earth's carbon cycle offer tantalizing clues to the history of atmospheric oxygen levels, and Kump and others have revealed unrecognized details of the timing and mechanism of the Great Oxidation Event," said Enriqueta Barrera, program director in the National Science Foundation's Division of Earth Sciences, which funded the research.
The cores from the FAR-DEEP project were compared with samples from Gabon using the ratio of carbon isotopes, or variants, 13 and 12 to see if the evidence for high rates of oxygen accumulation existed worldwide.
Both the FAR-DEEP project's cores and the Gabon cores show large deposits of carbon in the form of fossilized petroleum.
Both sets of cores also show similar changes in carbon 13 through time, indicating that the changes in carbon isotopes occurred worldwide and that oxygen levels throughout the atmosphere were high.
"Although others have documented huge carbon isotope variations at later times in Earth history associated with stepwise increases in atmospheric oxygen, our results are less equivocal because we have many lines of data all pointing to the same thing," said Kump.
"These indications include not only carbon 13 isotope profiles in organic mater from two widely separated locations, but also supporting profiles in limestones and no indication that processes occurring since that time have altered the signal."
Working with Kump on the project were geoscientists Michael Arthur of Penn State; Christopher Junium of Syracuse University; Alex Brasier and Anthony Fallick of the Scottish Universities Environmental Research Centre; Victor Melezhik, Aivo Lepland and Alenka Crne at the Norwegian Geological Survey; and Genming Luo, China University of Geosciences.
The NASA Astrobiology Institute also supported the research.
-NSF-
Guillermo Gonzalo Sánchez Achutegui
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