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  • richardmitnick 4:10 pm on December 26, 2014 Permalink | Reply
    Tags: , , Earth Sciences,   

    From NASA Earth Observatory: “What Lies Below” 

    NASA Earth Observatory

    NASA Earth Observatory

    During the Southern Hemisphere’s summer season, the South Pole bustles with science activity, from cosmic observations to seismic and atmospheric studies. This year, researchers are taking a close look at what lies below.

    1

    The image above shows a slice through almost 3 kilometers (1.9 miles) of ice spanning a few hundred kilometers on each side of the South Pole. (Note that the horizontal scale differs from the vertical scale.) From this perspective, ice would be flowing into the page, or away from you.

    Over many years, snow that fell at the surface has been compressed and transformed into successive layers of ice. The process continues and layers become further compressed under the tremendous weight of the ice sheet. The ice that makes up a single layer is a uniform age and contains information about the composition of the atmosphere at the time that the snow initially fell.

    Radar instruments on aircraft can detect these layers by transmitting microwave signals and recording the magnitude of the echoes returned to the instrument. The method works because the strength of the echo varies depending on factors such as density and the amount of impurities in each layer.

    In the radar image above, the stratigraphy (layers) appears misshapen in places, possibly caused by drag over rough bedrock “upstream” or from irregular ice flow. Orange lines highlight the part of the bedrock where the data are faint. White lines on either side of the South Pole are reflections from buildings at the surface.

    These radar data were collected during an airborne campaign in December 1998 led by the University of Texas Institute for Geophysics (UTIG). For two successive seasons, scientists with the Pensacola-Pole Transect campaign surveyed from the Ross Ice Shelf, southward over the Transantarctic mountains between the Scott and Reedy Glaciers, and over the South Pole. This particular scene was collected over the course of two days.

    r
    Map of Antarctica with the Ross ice shelf marked with a red X.

    rr
    Crevasse, Ross Ice Shelf in 2001

    According to Don Blankenship, whose UTIG team collected the data and later prepared this image, “this is one of the few and possibly the most recent image of this particular transect through the South Pole.” There has not yet been a scientific need to collect newer imagery across a such a large swath of the region.

    The view recently proved useful for scientists choosing a site for the drilling and recovery of a new ice core. Scientists began drilling in early December 2014, and when completed in 2016 the core will be the deepest yet recovered from near the South Pole. Scientists aim to drill down 1,500 meters (4,900 feet) to where the ice is about 40,000 years old. Analysis of the layers will provide a detailed history of the climate and environment in a unique area of the continent where moist air from the west meets cold, dry air from the east.

    According to NASA cryospheric scientist Tom Neumann: “The low temperature and relatively high accumulation rate here could give us an excellent record of the chemistry of the polar atmosphere over the last 40,000 years.”

    References and Further Reading
    Casey, K.A. et al., (2014) The 1500 m South Pole ice core: recovering a 40 ka environmental record. Annals of Glaciology 55 (68), 137-146.
    South Pole Ice Core (2014) Overview. Accessed December 22, 2014.
    National Snow & Ice Data Center (2014) <em>What is a glacier? Accessed December 22, 2014.
    University of Copenhagen Centre for Ice and Climate (2014) Ice core impurities Accessed December 22, 2014.

    Images courtesy of Don Blankenship and Marie Cavitte, University of Texas Institute for Geophysics (UTIG), based on work funded by the National Science Foundation. Caption by Kathryn Hansen.

    See the full article here.

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    The Earth Observatory’s mission is to share with the public the images, stories, and discoveries about climate and the environment that emerge from NASA research, including its satellite missions, in-the-field research, and climate models. The Earth Observatory staff is supported by the Climate and Radiation Laboratory, and the Hydrospheric and Biospheric Sciences Laboratory located at NASA Goddard Space Flight Center.

     
  • richardmitnick 8:29 pm on December 19, 2014 Permalink | Reply
    Tags: , Earth Sciences, ,   

    From NSF- “Geomagnetic reversal: Understanding ancient flips and flops in Earth’s polarity” 

    nsf
    National Science Foundation

    December 19, 2014
    Ivy F. Kupec, (703) 292-8796 ikupec@nsf.gov

    Investigators
    Masako Tominaga
    Maurice Tivey
    William Sager

    Related Institutions/Organizations
    Woods Hole Oceanographic Institution

    Locations
    Western Pacific Seafloor , Hawaii

    Related Programs
    Marine Geology and Geophysics

    Imagine one day you woke up, and the North Pole was suddenly the South Pole.

    This geomagnetic reversal would cause your hiking compass to seem impossibly backwards. However, within our planet’s history, scientists know that this kind of thing actually has happened…not suddenly and not within human time scales, but the polarity of the planet has in fact reversed, which has caused scientists to wonder not only how it’s happened, but why.

    This week, as the National Science Foundation (NSF) research vessel R/V Sikuliaq continues its journey towards its home port in University of Alaska Fairbanks’ Marine Center in Seward, Alaska, she detours for approximately 35 days as researchers take advantage of her close proximity to the western Pacific Ocean’s volcanic sea floors. With the help of three types of magnetometers, they will unlock more of our planet’s geomagnetic history that has been captured in our Earth’s crust there.

    1
    Before leaving port, an undergraduate student acquires important control data with a gravitometer.

    “The geomagnetic field is one of the major physical properties of planet Earth, and it is a very dynamic property that can change from milliseconds to millions of years. It is always, always changing,” said the expedition’s chief scientist, Masako Tominaga, an NSF-funded marine geophysicist from Michigan State University. “Earth’s geomagnetic field is a shield, for example. It protects us from magnetic storms–bursts from the sun–so very pervasive cosmic rays don’t harm us. Our research will provide data to understand how changes in the geomagnetic field have occurred over time and give us very important clues to understand the planet Earth as a whole.”

    Flipping and flopping

    Reportedly, the last time, a geomagnetic reversal occurred was 780,000 years ago, known as the Brunhes-Matuyama reversal. Bernard Brunhes and Motonori Matuyama were the geophysicists who identified that reversal in 1906.

    5
    A supercomputer to model flow patterns in Earth’s liquid core.
    Dr. Gary A. GlatzmaierLos Alamos National LaboratoryU.S. Department of Energy.

    Researchers Tominaga, Maurice Tivey (from Woods Hole Oceanographic Institution) and William Sager (from University of Houston) have an interest that goes further back in history to the Jurassic period, 145-200 million years ago when a curious anomaly occurred. Scientists originally thought that during this time period, no geomagnetic reversals had happened at all. However, data–like the kind that Tominaga’s team will be collecting–revealed that in fact, the time period was full of reversals that occurred much more quickly.

    “We came to the conclusion that it was actually ‘flipping flopping,’ but so fast that it did not regain the full strength of the geomagnetic field of Earth like today’s strength. That’s why it was super, super low,” Tominaga explained. “The Jurassic period is very distinctive. We think that understanding this part of the geomagnetic field’s behavior can provide important clues for computer simulation where researchers have been trying to characterize this flipping and flopping. Our data could help predict future times when we might see this flipping flopping again.”

    Interestingly, historical records have shown points where the flipping seems likely to occur but then seems to change its mind, almost like a tease, where it returns to its original state. Those instances actually do occur on a shorter time scale than the full-fledged flipping and flopping. Again, scientists are looking for answers on why they occur as well.

    Better tools equal better data

    For approximately three decades, researchers like Tominaga have been probing this area of the western Pacific seafloor. With her cruise on R/V Sikuliaq, Tominaga and Tivey come with even more technology in hand.

    Thirty years ago, researchers didn’t have access to autonomous underwater vehicles (AUV) that could go to deeper, harder-to-reach ocean areas. However, that is just one of three ways Tominaga’s team will deploy three magnetometers during its time at sea. One magnetometer will work from aboard R/V Sikuliaq. Another will trail behind the ship, and the third will be part of the AUV.

    “The seafloor spreading at mid-ocean ridge occurred because of volcanic eruption over time. And when this molten lava formed the seafloor, it actually recorded ambient geomagnetic data. So when you go from the very young ocean seafloor right next to the mid-ocean ridge to very, very old seafloor away from the mid-ocean ridge, a magnetometer basically unveils changes in the geomagnetic field for us,” Tominaga said. “The closer we can get to the seafloor, the better the signal. That’s the rule of thumb for geophysics.”

    With the help of R/V Sikuliaq’s ship’s crew, Tominaga and Tivey, a cruise archivist who is also a computer engineer/scientist, and seven students (three of whom are undergraduates), the team will run daily operations 24 hours a day/seven days a week, deploying the magnetometers, collecting data and then moving on to the next site.

    Naturally, the weather can waylay even the best plans. “Our goal is always about the science, but the road likely will be winding,” Tominaga said. “The most enjoyable part of this work is to be able to work together with this extremely diverse group of people. The Sikuliaq crew, the folks at UAF and those connected to the ship from NSF have all been committed to seeing this research happen, which is incredibly gratifying…. When we make things happen together as a team, it is really rewarding.”

    Focus on fundamentals

    Not surprisingly, this kind of oceanographic research is among some of the most fundamental, serving as a foundation for other research where it might correlate or illuminate. Additionally, because the causes and impacts of these geomagnetic changes are unknown, connections to currents, weather patterns, and other geologic phenomenon can still be explored also.

    “NSF, along with the entire science community, has waited years for this unique state-of-the-art Arctic vessel, and the timing couldn’t be more critical,” said Rose DuFour, NSF program director. “Our hope is to use R/V Sikuliaq to help carry out the abundant arctic-based seagoing science missions that go beyond NSF-funded science and extend to those from other federal agencies, like Office of Naval Research as well.”

    Tominaga notes that another key part to the cruise’s mission is record keeping; it’s why an archivist is part of her team. He even will blog daily (with pictures). As foundational research, it’s important to “keep every single record intact,” and she believes this broadcasting daily narrative will assist in this effort. Additionally, the plan is to share the collected data as soon as possible with other researchers who can benefit from it as well. “Without going there, getting real data–providing ground truth–how do we know what is going on?” Tominaga said, explaining fieldwork’s importance.

    Tominaga is quite clear on what prompts her to keep one of the busiest fieldwork schedules, even during a season usually reserved for family and friends, sipping eggnog or champagne. “I was raised as a scientist/marine geophysicist, and I don’t just mean academically,” she said. “I really looked up to my mentors and friends and how they handed down what they know-so unselfishly. And when I was finishing my Ph.D., I realized that there will be a time I will hand down these things to the next generation. Now, as a professor at Michigan State University, I’m the one who has to pass the torch, if you will–knowledge, experience, and skills at sea. That’s what drives me.”

    See the full article here.

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    The National Science Foundation (NSF) is an independent federal agency created by Congress in 1950 “to promote the progress of science; to advance the national health, prosperity, and welfare; to secure the national defense…we are the funding source for approximately 24 percent of all federally supported basic research conducted by America’s colleges and universities. In many fields such as mathematics, computer science and the social sciences, NSF is the major source of federal backing.

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  • richardmitnick 2:29 pm on August 22, 2014 Permalink | Reply
    Tags: , Earth Sciences,   

    From NASA: “Ozone-Depleting Compound Persists, NASA Research Shows “ 

    NASA

    NASA

    August 20, 2014
    Steve Cole
    Headquarters, Washington
    202-358-0918
    stephen.e.cole@nasa.gov

    Kathryn Hansen
    Goddard Space Flight Center, Greenbelt, Md.
    301-286-1046
    kathryn.h.hansen@nasa.gov

    NASA research shows Earth’s atmosphere contains an unexpectedly large amount of an ozone-depleting compound from an unknown source decades after the compound was banned worldwide.

    ball
    Satellites observed the largest ozone hole over Antarctica in 2006. Purple and blue represent areas of low ozone concentrations in the atmosphere; yellow and red are areas of higher concentrations. Image Credit: NASA

    Carbon tetrachloride (CCl4), which was once used in applications such as dry cleaning and as a fire-extinguishing agent, was regulated in 1987 under the Montreal Protocol along with other chlorofluorocarbons that destroy ozone and contribute to the ozone hole over Antarctica. Parties to the Montreal Protocol reported zero new CCl4 emissions between 2007-2012.

    However, the new research shows worldwide emissions of CCl4 average 39 kilotons per year, approximately 30 percent of peak emissions prior to the international treaty going into effect.

    “We are not supposed to be seeing this at all,” said Qing Liang, an atmospheric scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and lead author of the study. “It is now apparent there are either unidentified industrial leakages, large emissions from contaminated sites, or unknown CCl4 sources.”

    As of 2008, CCl4 accounted for about 11 percent of chlorine available for ozone depletion, which is not enough to alter the decreasing trend of ozone-depleting substances. Still, scientists and regulators want to know the source of the unexplained emissions.

    For almost a decade, scientists have debated why the observed levels of CCl4 in the atmosphere have declined slower than expectations, which are based on what is known about how the compound is destroyed by solar radiation and other natural processes.

    “Is there a physical CCl4 loss process we don’t understand, or are there emission sources that go unreported or are not identified?” Liang said.

    With zero CCl4 emissions reported between 2007-2012, atmospheric concentrations of the compound should have declined at an expected rate of 4 percent per year. Observations from the ground showed atmospheric concentrations were only declining by 1 percent per year.

    To investigate the discrepancy, Liang and colleagues used NASA’s 3-D GEOS Chemistry Climate Model and data from global networks of ground-based observations. The CCl4 measurements used in the study were made by scientists at the National Oceanic and Atmospheric Administration’s (NOAA’s) Earth System Research Laboratory and NOAA’s Cooperative Institute for Research in Environmental Sciences at the University of Colorado, Boulder.

    Model simulations of global atmospheric chemistry and the losses of CCl4 due to interactions with soil and the oceans pointed to an unidentified ongoing current source of CCl4. The results produced the first quantitative estimate of average global CCl4 emissions from 2000-2012.

    In addition to unexplained sources of CCl4, the model results showed the chemical stays in the atmosphere 40 percent longer than previously thought. The research was published online in the Aug. 18 issue of Geophysical Research Letters.

    “People believe the emissions of ozone-depleting substances have stopped because of the Montreal Protocol,” said Paul Newman, chief scientist for atmospheres at NASA’s Goddard Space Flight Center, and a co-author of the study. “Unfortunately, there is still a major source of CCl4 out in the world.”

    NASA monitors Earth’s vital signs from land, air and space with a fleet of satellites and ambitious airborne and ground-based observation campaigns. NASA develops new ways to observe and study Earth’s interconnected natural systems with long-term data records and computer analysis tools to better see how our planet is changing. The agency shares this unique knowledge with the global community and works with institutions in the United States and around the world that contribute to understanding and protecting our home planet.

    See the full article, with video, here.

    The National Aeronautics and Space Administration (NASA) is the agency of the United States government that is responsible for the nation’s civilian space program and for aeronautics and aerospace research.

    President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29, 1958, disestablishing NASA’s predecessor, the National Advisory Committee for Aeronautics (NACA). The new agency became operational on October 1, 1958.

    Since that time, most U.S. space exploration efforts have been led by NASA, including the Apollo moon-landing missions, the Skylab space station, and later the Space Shuttle. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle and Commercial Crew vehicles. The agency is also responsible for the Launch Services Program (LSP) which provides oversight of launch operations and countdown management for unmanned NASA launches. Most recently, NASA announced a new Space Launch System that it said would take the agency’s astronauts farther into space than ever before and lay the cornerstone for future human space exploration efforts by the U.S.

    NASA science is focused on better understanding Earth through the Earth Observing System, advancing heliophysics through the efforts of the Science Mission Directorate’s Heliophysics Research Program, exploring bodies throughout the Solar System with advanced robotic missions such as New Horizons, and researching astrophysics topics, such as the Big Bang, through the Great Observatories [Hubble,
    Chandra, Spitzer ]and associated programs. NASA shares data with various national and international organizations such as from the Greenhouse Gases Observing Satellite.

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  • richardmitnick 2:02 pm on July 30, 2014 Permalink | Reply
    Tags: , Earth Sciences, ,   

    From SPACE.com: “Early Earth: A Battered, Hellish World with Water Oases for Life “ 

    space-dot-com logo

    July 30, 2014
    Charles Q. Choi

    Asteroids and comets that repeatedly smashed into the early Earth covered the planet’s surface with molten rock during its earliest days, but still may have left oases of water that could have supported the evolution of life, scientists say.

    The new study reveals that during the planet’s infancy, the surface of the Earth was a hellish environment, but perhaps not as hellish as often thought, scientists added.

    Earth formed about 4.5 billion years ago. The first 500 million years of its life are known as the Hadean Eon. Although this time amounts to more than 10 percent of Earth’s history, little is known about it, since few rocks are known that are older than 3.8 billion years old.

    early earth
    depiction of possible early planet Earth

    Earth’s violent youth

    For much of the Hadean, Earth and its sister worlds in the inner solar system were pummeled with an extraordinary number of cosmic impacts.

    “It was thought that because of these asteroids and comets flying around colliding with Earth, conditions on early Earth may have been hellish,” said lead study author Simone Marchi, a planetary scientist at the Southwest Research Institute in Boulder, Colorado. This imagined hellishness gave the eon its name — Hadean comes from Hades, the lord of the underworld in Greek mythology.

    However, in the past dozen years or so, a radically different picture of the Hadean began to emerge. Analysis of minerals trapped within microscopic zircon crystals dating from this eon “suggested there was liquid water on the surface of the Earth back then, clashing with the previous picture that the Hadean was hellish,” Marchi said. This could explain why the evidence of the earliest life on Earth appears during the Hadean — maybe the planet was less inhospitable during that eon than previously thought.

    Cosmic bombardment history

    The exact timing and magnitude of the impacts that smashed Earth during the Hadean are unknown. To get an idea of the effects of this bombardment, Marchi and his colleagues looked at the moon, whose heavily cratered surface helped model the battering that its close neighbor Earth must have experienced back then.

    “We also looked at highly siderophile elements (elements that bind tightly to iron), such as gold, delivered to Earth as a result of these early collisions, and the amounts of these elements tells us the total mass accreted by Earth as the result of these collisions,” Marchi said. Prior research suggests these impacts probably contributed less than 0.5 percent of the Earth’s present-day mass.

    The researchers discovered that “the surface of the Earth during the Hadean was heavily affected by very large collisions, by impactors larger than 100 kilometers (60 miles) or so — really, really big impactors,” Marchi said. “When Earth has a collision with an object that big, that melts a large volume of the Earth’s crust and mantle, covering a large fraction of the surface,” Marchi added.

    These findings suggest that Earth’s surface was buried over and over again by large volumes of molten rock — enough to cover the surface of the Earth several times. This helps explain why so few rocks survive from the Hadean, the researchers said.

    However, although these findings might suggest that the Hadean was a hellish eon, the researchers found that “there were time gaps between these large collisions,” Marchi said. “Generally speaking, there may have been something on the order of 20 or 30 impactors larger than 200 km (120 miles) across during the 500 million years of the Hadean, so the time between such impactors was relatively long,” Marchi said.

    Any water vaporized near these impacts “would rain down again,” Marchi said, and “there may have been quiet tranquil times between collisions — there could have been liquid water on the surface.”

    The researchers suggested that life emerging during the Hadean was probably resistant to the high temperatures of the time. Marchi and his colleagues detailed their findings in the July 31 issue of the journal Nature.

    See the full article, with video, here.


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  • richardmitnick 3:45 pm on June 16, 2014 Permalink | Reply
    Tags: , Earth Sciences,   

    Fro Brookhaven Lab: “New Evidence for Oceans of Water Deep in the Earth” 

    Brookhaven Lab

    June 13, 2014
    Karen McNulty Walsh, (631) 344-8350 or Peter Genzer, (631) 344-3174printer iconPrint

    Water bound in mantle rock alters our view of the Earth’s composition

    Researchers from Northwestern University and the University of New Mexico report evidence for potentially oceans worth of water deep beneath the United States. Though not in the familiar liquid form — the ingredients for water are bound up in rock deep in the Earth’s mantle — the discovery may represent the planet’s largest water reservoir.

    earth
    Structure of the Earth

    The presence of liquid water on the surface is what makes our “blue planet” habitable, and scientists have long been trying to figure out just how much water may be cycling between Earth’s surface and interior reservoirs through plate tectonics.

    Northwestern geophysicist Steve Jacobsen and University of New Mexico seismologist Brandon Schmandt have found deep pockets of magma located about 400 miles beneath North America, a likely signature of the presence of water at these depths. The discovery suggests water from the Earth’s surface can be driven to such great depths by plate tectonics, eventually causing partial melting of the rocks found deep in the mantle.

    The findings, to be published June 13 in the journal Science, will aid scientists in understanding how the Earth formed, what its current composition and inner workings are and how much water is trapped in mantle rock.

    “Geological processes on the Earth’s surface, such as earthquakes or erupting volcanoes, are an expression of what is going on inside the Earth, out of our sight,” said Jacobsen, a co-author of the paper. “I think we are finally seeing evidence for a whole-Earth water cycle, which may help explain the vast amount of liquid water on the surface of our habitable planet. Scientists have been looking for this missing deep water for decades.”

    mntle
    A blue crystal of ringwoodite containing around one percent of H2O in its crystal structure is compressed to conditions of 700 km depth inside a diamond-anvil cell. Using a laser to heat the sample to temperatures over 1500C (orange spots), the ringwoodite transformed to minerals found in the lowermost mantle. Synchrotron-infrared spectra collected on beamline U2A at the NSLS reveal changes in the OH-absorption spectra that correspond to melt generation, which was also detected by seismic waves underneath most of North America.

    Scientists have long speculated that water is trapped in a rocky layer of the Earth’s mantle located between the lower mantle and upper mantle, at depths between 250 miles and 410 miles. Jacobsen and Schmandt are the first to provide direct evidence that there may be water in this area of the mantle, known as the “transition zone,” on a regional scale. The region extends across most of the interior of the United States.

    Schmandt, an assistant professor of geophysics at the University of New Mexico, uses seismic waves from earthquakes to investigate the structure of the deep crust and mantle. Jacobsen, an associate professor of Earth and planetary sciences at Northwestern’s Weinberg College of Arts and Sciences, uses observations in the laboratory to make predictions about geophysical processes occurring far beyond our direct observation.

    The study combined Jacobsen’s lab experiments in which he studies mantle rock under the simulated high pressures of 400 miles below the Earth’s surface with Schmandt’s observations using vast amounts of seismic data from the USArray, a dense network of more than 2,000 seismometers across the United States.

    Jacobsen’s and Schmandt’s findings converged to produce evidence that melting may occur about 400 miles deep in the Earth. H2O stored in mantle rocks, such as those containing the mineral ringwoodite, likely is the key to the process, the researchers said.

    “Melting of rock at this depth is remarkable because most melting in the mantle occurs much shallower, in the upper 50 miles,” said Schmandt, a co-author of the paper. “If there is a substantial amount of H2O in the transition zone, then some melting should take place in areas where there is flow into the lower mantle, and that is consistent with what we found.”

    If just one percent of the weight of mantle rock located in the transition zone is H2O, that would be equivalent to nearly three times the amount of water in our oceans, the researchers said.

    This water is not in a form familiar to us — it is not liquid, ice or vapor. This fourth form is water trapped inside the molecular structure of the minerals in the mantle rock. The weight of 250 miles of solid rock creates such high pressure, along with temperatures above 2,000 degrees Fahrenheit, that a water molecule splits to form a hydroxyl radical (OH), which can be bound into a mineral’s crystal structure.

    Schmandt and Jacobsen’s findings build on a discovery reported in March in the journal Nature in which scientists discovered a piece of the mineral ringwoodite inside a diamond brought up from a depth of 400 miles by a volcano in Brazil. That tiny piece of ringwoodite — the only sample in existence from within the Earth — contained a surprising amount of water bound in solid form in the mineral.

    “Whether or not this unique sample is representative of the Earth’s interior composition is not known, however,” Jacobsen said. “Now we have found evidence for extensive melting beneath North America at the same depths corresponding to the dehydration of ringwoodite, which is exactly what has been happening in my experiments.”

    For years, Jacobsen has been synthesizing ringwoodite, colored sapphire-like blue, in his Northwestern lab by reacting the green mineral olivine with water at high-pressure conditions. (The Earth’s upper mantle is rich in olivine.) He found that more than one percent of the weight of the ringwoodite’s crystal structure can consist of water — roughly the same amount of water as was found in the sample reported in the Nature paper.

    “The ringwoodite is like a sponge, soaking up water,” Jacobsen said. “There is something very special about the crystal structure of ringwoodite that allows it to attract hydrogen and trap water. This mineral can contain a lot of water under conditions of the deep mantle.”

    For the study reported in Science, Jacobsen subjected his synthesized ringwoodite to conditions around 400 miles below the Earth’s surface and found it forms small amounts of partial melt when pushed to these conditions. He detected the melt in experiments conducted at the Advanced Photon Source of Argonne National Laboratory and at the National Synchrotron Light Source of Brookhaven National Laboratory.

    Jacobsen uses small gem diamonds as hard anvils to compress minerals to deep-Earth conditions. “Because the diamond windows are transparent, we can look into the high-pressure device and watch reactions occurring at conditions of the deep mantle,” he said. “We used intense beams of X-rays, electrons and infrared light to study the chemical reactions taking place in the diamond cell.”

    Jacobsen’s findings produced the same evidence of partial melt, or magma, that Schmandt detected beneath North America using seismic waves. Because the deep mantle is beyond the direct observation of scientists, they use seismic waves — sound waves at different speeds — to image the interior of the Earth.

    “Seismic data from the USArray are giving us a clearer picture than ever before of the Earth’s internal structure beneath North America,” Schmandt said. “The melting we see appears to be driven by subduction — the downwelling of mantle material from the surface.”

    The melting the researchers have detected is called dehydration melting. Rocks in the transition zone can hold a lot of H2O, but rocks in the top of the lower mantle can hold almost none. The water contained within ringwoodite in the transition zone is forced out when it goes deeper (into the lower mantle) and forms a higher-pressure mineral called silicate perovskite, which cannot absorb the water. This causes the rock at the boundary between the transition zone and lower mantle to partially melt.

    “When a rock with a lot of H2O moves from the transition zone to the lower mantle it needs to get rid of the H2O somehow, so it melts a little bit,” Schmandt said. “This is called dehydration melting.”

    “Once the water is released, much of it may become trapped there in the transition zone,” Jacobsen added.

    Just a little bit of melt, about one percent, is detectible with the new array of seismometers aimed at this region of the mantle because the melt slows the speed of seismic waves, Schmandt said.

    The USArray is part of EarthScope, a program of the National Science Foundation that deploys thousands of seismic, GPS and other geophysical instruments to study the structure and evolution of the North American continent and the processes the cause earthquakes and volcanic eruptions.

    The National Science Foundation (grants EAR-0748797 and EAR-1215720) and the David and Lucile Packard Foundation supported the research.

    The paper is titled Dehydration melting at the top of the lower mantle. In addition to Jacobsen and Schmandt, other authors of the paper are Thorsten W. Becker, University of California, Los Angeles; Zhenxian Liu, Carnegie Institution of Washington; and Kenneth G. Dueker, the University of Wyoming

    See the full article here.

    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world.Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.
    i1


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  • richardmitnick 12:44 pm on March 29, 2013 Permalink | Reply
    Tags: , , , , Earth Sciences, ,   

    From PNNL Lab: “Striking While the Iron Is Hot” 

    Chromatography combined with database search strategy identifies hard-to-find heme proteins

    March 2013
    Suraiya Farukhi
    Christine Sharp

    Results: Heme c is an important iron-containing post-translational modification found in many proteins. It plays an important role in respiration, metal reduction, and nitrogen fixation, especially anaerobic respiration of environmental microbes. Such bacteria and their c-type cytochromes are studied extensively because of their potential use in bioremediation, microbial fuel cells, and electrosynthesis of valuable biomaterials.

    heme c
    Heme C

    Until recently, these modifications were hard to find using traditional proteomic methods. Scientists at Pacific Northwest National Laboratory combined a heme c tag protein affinity purification strategy called histidine affinity chromatography (HAC) with enhanced database searching. This combination confidently identified heme c peptides in liquid chromatography-tandem mass spectrometry (LC-MS/MS) experiments-by as much as 100-fold in some cases.”

    Why It Matters: Iron is a critical part of many biological processes; however, it is often not biologically available or it can be toxic in high quantities. So, biological systems have developed intricate methods to use and store iron. Many environmentally important microbes and microbial communities are rich in c-type cytochromes. Combining HAC and data analysis tailored to the unique properties of heme c peptides should enable more detailed study of the role of c-type cytochromes in these microbes and microbial communities.

    ‘Several proteomics studies have analyzed the expression of c-type cytochromes under various conditions,’ said PNNL postdoctoral researcher Dr. Eric Merkley, and lead author of a paper that appeared in the Journal of Proteome Research. ‘A shared feature of these studies is that the cytochrome-rich fractions, the cell envelope or extracellular polymeric substance, were purified and explicitly analyzed to efficiently detect cytochromes. Analyses of large-scale proteomics datasets have typically suggested that c-type cytochromes, particularly the heme c peptides, are under-represented.'”

    See the full article here.

    Pacific Northwest National Laboratory (PNNL) is one of the United States Department of Energy National Laboratories, managed by the Department of Energy’s Office of Science. The main campus of the laboratory is in Richland, Washington.

    PNNL scientists conduct basic and applied research and development to strengthen U.S. scientific foundations for fundamental research and innovation; prevent and counter acts of terrorism through applied research in information analysis, cyber security, and the nonproliferation of weapons of mass destruction; increase the U.S. energy capacity and reduce dependence on imported oil; and reduce the effects of human activity on the environment. PNNL has been operated by Battelle Memorial Institute since 1965.

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  • richardmitnick 12:20 pm on March 7, 2013 Permalink | Reply
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    From SLAC: “Unexpected Allies Help Bacteria Clean Uranium From Groundwater” 

    March 7, 2013
    Lori Ann White

    Since 2009, SLAC scientist John Bargar has led a team using synchrotron-based X-ray techniques to study bacteria that help clean uranium from groundwater in a process called bioremediation. Their initial goal was to discover how the bacteria do it and determine the best way to help, but during the course of their research the team made an even more important discovery: Nature thinks bigger than that.

    thtree
    From left to right: Sam Webb, John Bargar and Juan Lezama-Pacheco used X-rays from the Stanford Synchrotron Radiation Lightsource to discover Nature’s housecleaning secrets. Since the housecleaning involves uranium, their curiosity may have important benefits. (Credit: Matt Beardsley)

    The researchers discovered that bacteria don’t necessarily go straight for the uranium, as was often thought to be the case. The bacteria make their own, even tinier allies – nanoparticles of a common mineral called iron sulfide. Then, working together, the bacteria and the iron sulfide grab molecules of a highly soluble form of uranium known as U(VI), or hexavalent uranium, and transform them into U(IV), a less-soluble form that’s much less likely to spread through the water table. According to Barger, this newly discovered partnership may be the basis of a global geochemical process that forms deposits of uranium ore.

    And it’s all done using one of the most basic types of chemical reactions known: oxidation and reduction, commonly known as ‘redox.’ Redox reactions can be thought of as the transfer of electrons from donor atoms to atoms that are hungry for electrons, and they are a primary source of chemical energy for both living and non-living processes. Photosynthesis involves redox reactions, as does cell respiration. Iron oxidizes to form rust; batteries depend on redox reactions to store and release energy.

    ‘Redox transitions are a very fundamental process,’ Bargar said. ‘It’s the stuff of life. It’s how you breathe.'”

    The study, published Monday in the Proceeding of the National Academy of Sciences, was conducted at the Old Rifle site on the Colorado River, a former uranium ore processing site in the town of Rifle, Colo. The aquifer at the site is contaminated with uranium and is the focus of bioremediation field studies conducted by a larger team of scientists at Lawrence Berkeley National Laboratory and funded by the Department of Energy’s Office of Biological and Environmental Research. As part of their study, the LBNL team added acetate – essentially vinegar – to the aquifer in a series of injection wells to “feed the bugs,” as Bargar put it, allowing acetate to flow throughout the aquifer around the wells.

    See the full article here.

    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

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  • richardmitnick 2:59 pm on March 4, 2013 Permalink | Reply
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    From Argonne Lab: “Doubling Estimates of Light Elements in the Earth’s Core” 

    Argonne National Laboratory

    MARCH 1, 2013
    Zhu Mao

    The inner core of the Earth is the remotest area on the globe, mostly impossible to study directly. It is an area of the planet that experiences both extremely high pressure ranging from 3,300,000 to 3,600,000 times atmospheric pressure, and extremely high temperatures somewhere from 5000 to 6000 K. One way to study this area is by recording how sound waves travel across the interior, matching these profiles to known information about how sound waves travel through candidate iron alloys, and attempting to discern which materials must be present. This method requires an understanding of how sound waves travel through the potential materials present in the core. A team of researchers utilized APS x-rays to develop a new model of how sound waves travel through iron and iron-silicon alloys, showing for the first time that increased temperatures will affect the sound wave profile, and that sound velocity and density correlate in a non-linear way. Their results suggest that the amount of light elements in the inner core could be two times more than estimated in previous studies without considering these effects.

    plots
    Velocity-density plots of the samples at high pressures and temperatures. The top panel shows the velocity-density plot for hcp-Fe at both 300 K and 700 K. The dashed lines shows the linear fit, while the solid line shows the power law fit, which matches the data more closely. The bottom panel shows the velocity-density relation of both hcp-Fe and the iron-silicon alloy at 300 K.

    earth core

    See the full article here.

    Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science

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  • richardmitnick 3:20 pm on January 10, 2013 Permalink | Reply
    Tags: , Earth Sciences, ,   

    From Livermore Lab: “Oxygen to the core” 


    Lawrence Livermore National Laboratory

    01/10/2013
    Anne M Stark

    An international collaboration including researchers from Lawrence Livermore National Laboratory has discovered that the Earth’s core formed under more oxidizing condition’s than previously proposed.

    core
    Home Sweet Home

    Through a series of laser-heated diamond anvil cell experiments at high pressure (350,000 to 700,000 atmospheres of pressure) and temperatures (5,120 to 7,460 degrees Fahrenheit), the team demonstrated that the depletion of siderophile (also known as “iron loving”) elements can be produced by core formation under more oxidizing conditions than earlier predictions.

    ‘We found that planet accretion (growth) under oxidizing conditions is similar to those of the most common meteorites, said LLNL geophysicist Rick Ryerson.

    The research appears in the Jan. 10 edition of Science Express.

    Other teams members include Julien Siebert and Daniele Antonangeli (former LLNL postdocs) from the Université Pierre et Marie Curie, and James Badro (a faculty scholar at LLNL) from the Institut de Physique du Globe de Paris.

    See the full and enlightening article here.

    Operated by Lawrence Livermore National Security, LLC, for the Department of Energy’s National Nuclear Security
    Administration

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  • richardmitnick 5:03 pm on January 4, 2013 Permalink | Reply
    Tags: , , Earth Sciences   

    From Berkeley Lab: “A New Way to Study Permafrost Soil, Above and Below Ground” 


    Berkeley Lab

    Berkeley Lab research could lead to a better understanding of the Arctic ecosystem’s impact on the planet’s climate

    January 03, 2013
    Dan Krotz

    What does pulling a radar-equipped sled across the Arctic tundra have to do with improving our understanding of climate change? It’s part of a new way to explore the little-known world of permafrost soils, which store almost as much carbon as the rest of the world’s soils and about twice as much as is in the atmosphere.

    Berkeley Permafrost

    The new approach combines several remote-sensing tools to study the Arctic landscape—above and below ground—in high resolution and over large spatial scales. It was developed by a group of researchers that includes scientists from the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab).

    They use ground-penetrating radar, electrical resistance tomography, electromagnetic data, and LiDAR airborne measurements. Together, these tools allow the scientists to see the different layers of the terrestrial ecosystem, including the surface topography, the active layer that seasonally freezes and thaws, and the deeper permafrost layer.

    The goal is to help scientists determine what will happen to permafrost-trapped carbon as the climate changes. Will it stay put? Or will it enter the atmosphere and accelerate climate change?

    lidar
    The scientists use data from airborne Lidar, surface geophysical measurements, and point measurements to explore the complex relationships between different layers of permafrost soil.

    ‘By combining surface geophysical and airborne remote-sensing methods, we have a new window that allows us to study permafrost systems like never before,’ says Susan Hubbard, a geophysicist in Berkeley Lab’s Earth Sciences Division who leads the Lab’s participation in the NGEE-Arctic collaboration.

    ngee

    Carbon sequestration and carbon dioxide are constants in our lives, making this a very important research. See the full article here.

    A U.S. Department of Energy National Laboratory Operated by the University of California

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