Kelsey et al. Figure 1: Location map of Sumatra, Indonesia, depicting rupture areas for the AD 2004 and 2005 subduction zone earthquakes
The 26 December 2004 Mw ~9.2 Indian Ocean earthquake (also known as the Sumatra-Andaman or Aceh-Andaman earthquake), which generated massive, destructive tsunamis, especially along the Aceh coast of northern Sumatra, Indonesia, clearly demonstrated the need for a better understanding of how frequently subduction zone earthquakes and tsunamis occur. Toward that end, Harvey M. Kelsey of Humboldt State University and colleagues present a study of earthquake history in the area.
Using subsidence stratigraphy, the team traced the different modes of coastal sedimentation over the course of time in the eastern Indian Ocean where relative sea-level change evolved from rapidly rising to static from 8,000 years ago to the present day.
Kelsey and colleagues discovered that 3,800 to 7,500 years ago, while sea level was gradually rising, there were seven subduction zone earthquakes recorded in coastal deposits. This was determined in part by the fact that each earthquake caused burial of a mangrove soil by sediment and/or deposition of tsunami sand at the time of the earthquake.
The team also discovered that sea level gradually stopped rising about 3,800 years ago, which meant that buried soils no longer formed. Thus, detecting subduction zone earthquakes required a different approach. They found a record of successive earthquakes in a sequence of stacked tsunami deposits on the coastal plain. Individual tsunami deposits were 0.2 to 0.5 m thick. Based on this information, Kelsey and colleagues determined that in the past 3,800 years there were between four and six tsunamis caused by Andaman-Aceh-type earthquakes.
The authors conclude that knowing the relative sea-level record for a coastal region on a subduction zone margin is the initial step in investigating paleoseismic history. For mid-latitude coasts that border subduction zones, sequences of buried soils may provide a long-duration, subsidence stratigraphic paleoseismic record that spans to the present, but in other settings such as the Aceh coastal plain, joint research approaches, for example targeted foraminiferal analyses and palynology, are required to both exploit the changing form of the relative sea-level curve and characterize coastal evolution in the context of the diminishing importance of accommodation space.
Reference:
“Accommodation space, relative sea level, and the archiving of paleo-earthquakes along subduction zones.” Geology, G36706.1, first published on June 23, 2015, DOI: 10.1130/G36706.1
This is a virtual section through the tooth plate of Romundina stellina, with colors gold through purple indicating the first up to the final tooth addition. Credit: Martin Rücklin, Naturalis Biodiversity Center
The tooth plate of just some millimeters in size had been in a box for more than 40 years, without being recognized after the discovery and preparation of the fish it belonged to. Palaeontologists from Naturalis Biodiversity Center, Netherlands and the University of Bristol, United Kingdom, studied the fossil using high energy X-rays at the Swiss Light Source at the Paul Scherrer Institut in Switzerland, revealing the structure and development of teeth and bones. Their findings are published today in Biology Letters.
Teeth are important in our daily life, they are crucial to munch and crunch our food. Jaws and teeth have been important innovations in the evolution of vertebrate animals. More than 98% of vertebrate animals have jaws.
Nevertheless earliest conditions and their origin are disguised in deep time. The search for fossil teeth of the earliest jawed vertebrates can literally be like the search for the needle in a haystack. This includes looking through boxes full of crumb sized bits and pieces of fossils remaining after dissolving rocks in acid.
Lead author, Martin Rücklin of Naturalis Biodiversity Center in Leiden says: “We were able to visualize the finest internal structures and distinguish tissues inside one of the first tooth plates. With powerful computing we combined thousands of X-rays and produced computer models reconstructing the growth of the first teeth.”
Philip Donoghue from the University of Bristol in the UK explains: “We show that the earliest teeth were like our own – but also structured like body scales in primitive fishes. This supports the view that teeth evolved from scales, which arose much earlier in vertebrate evolution.”
Rücklin adds: “Our results suggest that teeth originated deeper in the tree of life than we thought. We will have to look into more basal jawed vertebrates and also jawless fossils. Earliest jaws and teeth seem to be less integrated than we thought and teeth look more complex than expected. I am very happy that my research and our collaboration will be supported by the Vidi-grant of the Netherlands Organization for Scientific Research (NWO) in the next five years, enabling us to investigate these early stages of teeth and how the complex system of our own jaws and teeth evolved.”
Video
Reference:
M. Rucklin, P. C. J. Donoghue. Romundina and the evolutionary origin of teeth. Biology Letters, 2015; 11 (6): 20150326 DOI: 10.1098/rsbl.2015.0326
Uplift in the Santa María island as a result of the Maule earthquake in 2010. The island experienced a sudden uplift about 2 meters during the earthquake. Credit: Photo: M. Moreno, GFZ
Charles Darwin and his captain Robert Fitzroy witnessed the great earthquake of 1835 in south central Chile. The “Beagle”-Captain’s precise measurements showed an uplift of the island Isla Santa María of 2 to 3 meters after the earthquake. What Darwin and Fitzroy couldn’t know was the fact that 175 years later nearly at the same position such a strong earthquake would recur.
At the South American west coastline the Pacific Ocean floor moves under the South American continent. Resulting that through an in- and decrease of tension the earth’s crust along the whole continent from Tierra del Fuego to Peru broke alongside the entire distance in series of earthquakes within one and a half century. The earthquake of 1835 was the beginning of such a seismic cycle in this area.
After examining the results of the Maule earthquake in 2010 a team of geologists from Germany, Chile and the US for the first time were able to measure and simulate a complete seismic cycle at its vertical movement of the earth’s crust at this place.
In the current online-edition of Nature Geoscience they report about the earthquakes: After the earthquake of 1835 with a magnitude of about 8,5 Isla Santa María was uplifted up to 3 m, subsided again about 1,5 m in the following 175 years, and upliftet anew 1,5-2 m caused by the Maule earthquake with a moment magnitude scale of 8,8.
The Maule earthquake belongs to the great earthquakes, which was fully recorded and therefore well documented by a modern network of space-geodetical and geophysical measuring systems on the ground. More difficult was the reconstruction of the processes in 1835. But nautical charts from 1804 before the earthquake, from 1835 and 1886 as well as the precise documentation of captain Fitzroy allow in combination with present-day methods a sufficient accurate determination of the vertical movement of the earth’s crust along a complete seismic cycle.
At the beginning of such a cycle energy is stored by elastic deformation of the earth’s crust, then released at the time of the earthquake. “But interestingly, our observations hint at a variable subsidence rate during the seismic cycle” explains Marcos Moreno from GFZ German Research Centre for Geosciences, one of the co-authors. “Between great earthquakes the plates beneath Isla Santa María are large locked, dragging the edge of the South American plate, and the island upon it, downward and eastward.” During the earthquakes, motion is suddenly reversed and the edge of the South America Plate and island are thrust upward and to the west.” This complex movement pattern could be perfectly confirmed by a numerical model. In total, over time arises a permanent vertical uplift of 10 to 20% of the complete uplift.
Records of earthquakes show that there are no periodically sequence repetition times or consistent repeating magnitudes of earthquakes. An important instrument for a better estimation of risks caused by earthquakes are the compilation and measurement of earth’s crust deformation through an entire seismic cycle.
Reference:
Robert L. Wesson, Daniel Melnick, Marco Cisternas, Marcos Moreno, Lisa L. Ely. Vertical deformation through a complete seismic cycle at Isla Santa María, Chile. Nature Geoscience, 2015; DOI: 10.1038/NGEO2468
The elasmosaur piece discovered by Aiden Taylor during the middle school Museum Expedition.
Young Aiden Taylor loves all things dinosaur, so it seemed only natural for him to participate in The University of Alabama’s Museum Expedition this summer.
The 12-year-old Bay Minette native, however, found something that ignited his passion for paleontology even more during his week-long adventure in Greene County.
Taylor recently discovered a baseball-sized neck vertebra from an elasmosaur.
“Half of it was sticking out of the ground,” Taylor said. “It was huge, twice the size of my fist, and I knew I found something good. I yelled to everyone to come over.”
Dana Ehret, Alabama Museum of Natural History paleontologist, said the piece definitely belonged to an elasmosaur.
“The other types of reptile vertebrae that we commonly find in the Mooreville chalk—the geological formation where the vertebrae was found—belong to mosasaurs,” he said. “Mosasaur vertebrae look much different, with a front side that is concave and a back side that is convex. Elasmosaurs, on the other hand, have flattened front and back surfaces.”
A subgroup of the late Cretaceous plesiosaurs, elasmosaurid plesiosaurs are easily recognized by their large body size – some species reach up to 45 feet in length. Although elasmosaurs lived near the end of the dinosaur age – from about 90 million to 65 million years ago – Ehret said the species was not a dinosaur.
Plesiosaurs became extinct by the end of Cretaceous, or about 65.5 million years ago, and they are rare in the fossil record for Alabama. The first elasmosaurid specimen containing more than one or two bones found in the state was discovered in the late 1960s. It consisted of 22 vertebrae, and it is now part of UA Collections. Middle school student Noah Traylor made the second discovery two years ago, also while participating in the middle school Museum Expedition.
“The piece recently discovered definitely belongs to the specimen found two years ago,” Ehret said. “It was found exactly in the same area where the others were found two years ago, and we were specifically looking in that area for more vertebrae.”
The specimen will be prepared and cleaned in the Paleontology Prep Lab, then examined and kept in the collections with the other vertebrae collected two years ago. Ehret said museum staff will continue to check the site periodically to see if more of the specimen erodes out of the chalk. He has also reached out to a professor at Marshall University who specializes in plesiosaurs in an attempt to arrange a visit.
“Finds like this are important because it gives paleontologists a picture into what life was like 80 million years ago in Alabama,” he said. “While we typically find mosasaurs, fish, turtles, sharks, invertebrates and even bird fossils sometimes, elasmosaur fossils tend to be extremely rare.
“When we do find these types of specimens, it helps us to flesh out a more accurate picture of what the Cretaceous sea off the coast of Alabama looked like.
“We can also use these types of specimens to look at how faunas change through time and how reptiles, fish, sharks and invertebrates respond to changes in climate and environment. This is important today because we are undergoing climate changes that are unprecedented in the last 50 plus million years. Fossils can be important for looking at how different groups respond to these large-scale change,” he added.
For Taylor, it’s a great memory that he will carry with him for the rest of his life.
“I love prehistoric animals because they’re just cool,” he said. “They’re unusual, they’ve adapted, evolved and become the creatures that we know today—preserved creatures that amaze people.”
A crinoid is an ocean animal that has long, feathery arms that extend into the water column and use their tiny, sticky tube feet to pick up particles for food. Credit: CAGE
Close to 30,000 high definition images of the deep Arctic Ocean floor were captured on a recent research cruise. This gives researchers insight into the most remote sites of natural methane release in the world.
Over a course of 12 days Dr. Giuliana Panieri and her colleagues from Centre for Arctic Gas Hydrate, Environment and Climate collected images from seven areas of known methane release in the Arctic Ocean. One of them was Vestnesa Ridge, with over 1000 active seep sites at the depth of over 1000 m.
Dr. Panieri collaborated with scientists and engineers at Woods Hole Oceanographic Institution’s MISO Deep-Sea Imaging Facility. The aim was to get a proper view of the deep Arctic Ocean floor.
“We have taken so many samples all over these areas, but we were sampling blind. We needed to see what was going on down there.” sais Panieri who is an awe of the results achieved during the two-week cruise.
The system that was used to get these images is based on the ‘TowCam’ design developed by WHOI scientists and engineers, and funded by the US National Science Foundation. It consists of a color still camera that takes images every 10-15 seconds.
“This is the first time that we have seen these methane seeps in the deep Arctic Ocean areas. The images are amazing.” sais Panieri.
The midnight sun allowed for the tow cam system to be deployed 24/7 providing scientist with data that will be crucial in new discoveries in years to come.
DNA taken from a 40,000-year-old modern human jawbone reveals that this man had a Neandertal ancestor as recently as four to six generations back. Credit: MPI f. Evolutionary Anthropology/ Paabo
Neanderthals became extinct about 40,000 years ago but contributed on average one to three percent to the genomes of present-day Eurasians. Researchers have now analyzed DNA from a 37,000 to 42,000-year-old human mandible from Oase Cave in Romania and have found that six to nine percent of this person’s genome came from Neanderthals, more than any other human sequenced to date. Because large segments of this individual’s chromosomes are of Neanderthal origin, a Neanderthal was among his ancestors as recently as four to six generations back in his family tree. This shows that some of the first modern humans that came to Europe mixed with the local Neanderthals.
All present-day humans who have their roots outside sub-Saharan Africa carry one to three percent of Neanderthal DNA in their genomes. Until now, researchers have thought it most likely that early humans coming from Africa mixed with Neanderthals in the Middle East around 50,000 to 60,000 years ago, before spreading into Asia, Europe and the rest of the world. However, radiocarbon dating of remains from sites across Europe suggests that modern humans and Neanderthals both lived in Europe for up to 5,000 years and that they may have interbred there, too.
In 2002, a 40,000-year-old jawbone was found by cavers in Oase Cave in south-western Romania and the site was subsequently studied by an international team led by the researchers of the Emil Racovita Institute of Speleology in Romania. Researchers from the Max Planck Institute for Evolutionary Anthropology (Germany), Harvard Medical School (USA), and the Key Laboratory of Vertebrate Evolution and Human Origins in Beijing (China) have now analyzed DNA from this fossil, which is one of the earliest modern-human remains found in Europe. They estimate that five to 11 percent of the genome preserved in the bone derives from a Neanderthal ancestor, including exceptionally large segments of some chromosomes. By estimating how lengths of DNA inherited from an ancestor shorten with each generation, the researchers estimated that the man had a Neanderthal ancestor in the previous four to six generations.
“The data from the jawbone imply that humans mixed with Neanderthals not just in the Middle East but in Europe as well” says Qiaomei Fu, one of the lead researchers of the study. “Interestingly, the Oase individual does not seem to have any direct descendants in Europe today,” says David Reich from Harvard Medical School who coordinated the population genetic analyses of the study. “It may be that he was part of an early migration of modern humans to Europe that interacted closely with Neanderthals but eventually became extinct.”
“It is such a lucky and unexpected thing to get DNA from a person who was so closely related to a Neanderthal” comments Svante Paabo from the Max Planck Institute for Evolutionary Anthropology who led the study. “I could hardly believe it when we first saw the results.” “We hope that DNA from other human fossils that predate the extinction of Neanderthals will help reconstruct the interactions between Neanderthals and modern humans in even more detail,” says Mateja Hajdinjak, another key researcher involved in the study.
“When we started the work on Oase site, everything was already pointing to an exceptional discovery,” remembers Oana Moldovan, the Romanian researcher who initiated the systematic excavation of the cave in 2003. “But such discoveries require painstaking research to be confirmed,” adds Silviu Constantin, her colleague who worked on dating of the site. “We have previously shown that Oase is indeed the oldest modern human in Europe known so far, and now this research confirms that the individual had a Neanderthal ancestor. What more could we wish for?”
Reference:
Qiaomei Fu, Mateja Hajdinjak, Oana Teodora Moldovan, Silviu Constantin, Swapan Mallick, Pontus Skoglund, Nick Patterson, Nadin Rohland, Iosif Lazaridis, Birgit Nickel, Bence Viola, Kay Prüfer, Matthias Meyer, Janet Kelso, David Reich, Svante Pääbo. An early modern human from Romania with a recent Neanderthal ancestor. Nature, 2015; DOI: 10.1038/nature14558
Chart shows the enormous uptick in species loss over the last century. Credit: Image courtesy of Stanford University
There is no longer any doubt: We are entering a mass extinction that threatens humanity’s existence.
That is the bad news at the center of a new study by a group of scientists including Paul Ehrlich, the Bing Professor of Population Studies in biology and a senior fellow at the Stanford Woods Institute for the Environment. Ehrlich and his co-authors call for fast action to conserve threatened species, populations and habitat, but warn that the window of opportunity is rapidly closing.
“[The study] shows without any significant doubt that we are now entering the sixth great mass extinction event,” Ehrlich said.
Although most well known for his positions on human population, Ehrlich has done extensive work on extinctions going back to his 1981 book, Extinction: The Causes and Consequences of the Disappearance of Species. He has long tied his work on coevolution, on racial, gender and economic justice, and on nuclear winter with the issue of wildlife populations and species loss.
There is general agreement among scientists that extinction rates have reached levels unparalleled since the dinosaurs died out 66 million years ago. However, some have challenged the theory, believing earlier estimates rested on assumptions that overestimated the crisis.
The new study, published in the journal Science Advances, shows that even with extremely conservative estimates, species are disappearing up to about 100 times faster than the normal rate between mass extinctions, known as the background rate.
“If it is allowed to continue, life would take many millions of years to recover, and our species itself would likely disappear early on,” said lead author Gerardo Ceballos of the Universidad Autónoma de México.
Using fossil records and extinction counts from a range of records, the researchers compared a highly conservative estimate of current extinctions with a background rate estimate twice as high as those widely used in previous analyses. This way, they brought the two estimates — current extinction rate and average background or going-on-all-the-time extinction rate — as close to each other as possible.
Focusing on vertebrates, the group for which the most reliable modern and fossil data exist, the researchers asked whether even the lowest estimates of the difference between background and contemporary extinction rates still justify the conclusion that people are precipitating “a global spasm of biodiversity loss.” The answer: a definitive yes.
“We emphasize that our calculations very likely underestimate the severity of the extinction crisis, because our aim was to place a realistic lower bound on humanity’s impact on biodiversity,” the researchers write.
To history’s steady drumbeat, a human population growing in numbers, per capita consumption and economic inequity has altered or destroyed natural habitats. The long list of impacts includes:
Land clearing for farming, logging and settlement
Introduction of invasive species
Carbon emissions that drive climate change and ocean acidification
Toxins that alter and poison ecosystems
Now, the specter of extinction hangs over about 41 percent of all amphibian species and 26 percent of all mammals, according to the International Union for Conservation of Nature, which maintains an authoritative list of threatened and extinct species.
“There are examples of species all over the world that are essentially the walking dead,” Ehrlich said.
As species disappear, so do crucial ecosystem services such as honeybees’ crop pollination and wetlands’ water purification. At the current rate of species loss, people will lose many biodiversity benefits within three generations, the study’s authors write. “We are sawing off the limb that we are sitting on,” Ehrlich said.
Hope for the future
Despite the gloomy outlook, there is a meaningful way forward, according to Ehrlich and his colleagues. “Avoiding a true sixth mass extinction will require rapid, greatly intensified efforts to conserve already threatened species, and to alleviate pressures on their populations — notably habitat loss, over-exploitation for economic gain and climate change,” the study’s authors write.
In the meantime, the researchers hope their work will inform conservation efforts, the maintenance of ecosystem services and public policy.
Co-authors on the paper include Anthony D. Barnosky of the University of California at Berkeley, Andrés García of Universidad Autónoma de México, Robert M. Pringle of Princeton University and Todd M. Palmer of the University of Florida.
Video
Reference:
Gerardo Ceballos, Paul R. Ehrlich, Anthony D. Barnosky, Andrés García, Robert M. Pringle and Todd M. Palmer. Accelerated modern human–induced species losses: Entering the sixth mass extinction. Science Advances, 2015 DOI: 10.1126/sciadv.1400253
Note: The above post is reprinted from materials provided by Stanford University. The original item was written by Rob Jordan.
Major fluxes of carbon estimated by Craig Manning and Peter Kelemen. Credit: Courtesy of Josh Wood
Over billions of years, the total carbon content of the outer part of the Earth — in its upper mantle, crust, oceans, and atmospheres — has gradually increased, scientists reported this month in the journal Proceedings of the National Academy of Sciences.
Craig Manning, a professor of geology and geochemistry at UCLA, and Peter Kelemen, a geochemistry professor at Columbia University, present new analyses that represent an important advance in refining our understanding of Earth’s deep carbon cycle.
Manning and Kelemen studied how carbon, the chemical basis of all known life, behaves in a variety of tectonic settings. They assessed, among other factors, how much carbon is added to Earth’s crust and how much carbon is released into the atmosphere. The new model combines measurements, predictions and calculations.
Their research includes analysis of existing data on samples taken at sites around the world as well as new data from Oman.
The carbon ‘budget’ near the Earth’s surface exerts important controls on global climate change and our energy resources, and has important implications for the origin and evolution of life, Manning said. Yet much more carbon is stored in the deep Earth. The surface carbon that is so important to us is made available chiefly by volcanic processes originating deep in the planet’s interior.
Today carbon can return to Earth’s deep interior only by subduction — the geologic process by which one tectonic plate moves under another tectonic plate and sinks into the Earth’s mantle. Previous research suggested that roughly half of the carbon stored in subducted oceanic mantle, crust and sediments makes it into the deep mantle. Kelemen and Manning’s new analysis suggests instead that subduction may return almost no carbon to the mantle, and that ‘exchange between the deep interior and surface reservoirs is in balance.’
Some carbon must make it past subduction zones. Diamonds form in the mantle both from carbon that has never traveled to Earth’s surface, known as primordial carbon, and from carbon that has cycled from the mantle to the surface and back again, known as recycled carbon. Manning and Kelemen corroborated their findings with a calculation based on the characteristics of diamonds, which form from carbon in the earth’s mantle.
Deep carbon is important because the carbon at the Earth’s surface, on which we depend, ‘exists only by permission of the deep Earth,’ Manning said, quoting a friend. At times in the Earth’s history, the planet has been warmer (in the Cretaceous period, for example), and shallow seas covered North America. The new research sheds light on the Earth’s climate over geologic time scales.
The melting of Greenland contributes to the global sea level, but the loss of mass also means that the ice sheet’s own gravitational field weakens and thus does not attract the surrounding sea as strongly. This means that the sea will fall up to 2,000 km away from the ice sheet, and that the sea level in Northern Europe is not particularly sensitive to the melting of Greenland. Credit: Grinsted, Jevrejeva, Riva, and Dahl-Jensen
Global warming leads to the ice sheets on land melting and flowing into the sea, which consequently rises. New calculations by researchers from the Niels Bohr Institute show that the sea level in Northern Europe may rise more than previously thought. There is a significant risk that the seas around Scandinavia, England, the Netherlands and northern Germany will rise by up to about 1½ meters in this century. The results are published in a special issue of the scientific journal Climate Research.
Sea level rise is a significant threat to the world’s coastal areas, but the threat is not the same everywhere on Earth – it depends on many regional factors.
“Even though the oceans are rising, they do not rise evenly across the globe. This is partly due to regional changes in the gravitational field and land uplift,” explains Aslak Grinsted, associate professor at the Centre for Ice and Climate at the Niels Bohr Institute, University of Copenhagen.
He explains that gravity over the surface of the land and sea varies due to differences in the subsurface and surroundings – the greater the mass, the greater the gravity. The enormous ice sheet on Greenland attracts the sea, which consequently becomes higher around Greenland. When the ice sheet melts and flows out to sea as water, this attraction is reduced and even though more water has entered the sea, the sea level around Greenland would fall.
Another very important effect for Northern Europe is that during the ice age we had a thick ice sheet that weighted down the land. When the weight disappears, then the land rises and even though it has been more than 10,000 years since the ice disappeared, the land is still rising. The calculations show that in the Gulf of Bothnia the land is still rising faster than the expected sea level rise.
The UN Intergovernmental Panel on Climate Change (IPCC) has estimated that the average global warming in this century will rise by 4°C in a business-as-usual scenario. That is to say, if we continue to emit greenhouse gases as we have up to now. The effect will be a rise in sea levels.
“Based on the UN climate panel’s report on sea level rise, supplemented with an expert elicitation about the melting of the ice sheets, for example,how fast the ice on Greenland and Antarctica will melt while considering the regional changes in the gravitational field and land uplift, we have calculated how much the sea will rise in Northern Europe,” explains Aslak Grinsted.
Higher increase than expected
The calculations show that there is a real risk that what have been regarded as high scenarios in the Netherlands and England will be surpassed.
“For London, the calculated best estimate is that sea level will rise by 0.8 meters. In England, a sea level rise of more than 0.9 meters in this century has been considered highly unlikely, but our new calculation shows that there is a 27% chance that this limit is surpassed and we can not exclude a sea level rise of up to 1.75 meters this century,” explains Aslak Grinsted.
For the Netherlands, the best estimate of sea level rise is 0.83 meters, but the calculations show that there is a 26% chance that it will exceed the existing high-end scenario of 1.05 meters and a sea level rise of up to 1.80 meters cannot be excluded.
“Both countries have already established protections for the coasts with barriers, sluice gates, and dikes, but is it enough? I hope that our calculations for worst-case-scenarios will be taken into consideration as the countries prepare for climate change,” says Aslak Grinsted.
Copenhagen is slightly less exposed. Here the best estimate is that sea levels will rise by 0.68 meters, but there is a risk of increases up to 1.6 meters.
But even though the sea level around the world will rise by an average of 80 cm, the sea level in the Gulf of Bothnia in Finland is expected to fall by 10 cm due to land uplift. The land is rising faster than the sea is rising.
The reduced gravitational attraction of the Greenland ice sheet will result in lower sea levels as far away as 2000 km from Greenland in Ireland, Scotland and Norway. This means that the melting from Greenland will contribute 14 cm to the global sea level, but locally in Edinburgh it will result in a fall of 4 cm.
Aslak Grinsted explains that the great uncertainty in relation to future global sea level rise is how quickly the ice on Antarctica will melt and whether it will happen in a large collapse. But even without a collapse of the ice on Antarctica, vulnerable countries should prepare contingency plans in their coastal defence for the ‘worst-case-scenario’.
Large volumes of highly saline water extracted along with oil and gas from some producing formations gets injected into a deep disposal zone, the Arbuckle Formation, which sits directly upon crystalline basement rocks. Rising pore pressure in the Arbuckle Formation can penetrate already-stressed basement faults and trigger earthquakes. Credit: Steven Than/Stanford University
Stanford geophysicists have identified the triggering mechanism responsible for the recent spike of earthquakes in parts of Oklahoma — a crucial first step in eventually stopping them.
In a new study published in the June 19 issue of the journal Science Advances, Professor Mark Zoback and PhD student Rall Walsh show that the state’s rising number of earthquakes coincided with dramatic increases in the disposal of salty wastewater into the Arbuckle formation, a 7,000-foot-deep, sedimentary formation under Oklahoma.
In addition, the pair showed that the primary source of the quake-triggering wastewater is not so-called “flow back water” generated after hydraulic fracturing operations. Rather, the culprit is “produced water”-brackish water that naturally coexists with oil and gas within the Earth. Companies separate produced water from extracted oil and gas and typically reinject it into deeper disposal wells.
“What we’ve learned in this study is that the fluid injection responsible for most of the recent quakes in Oklahoma is due to production and subsequent injection of massive amounts of wastewater, and is unrelated to hydraulic fracturing,” said Zoback, the Benjamin M. Page Professor in the School of Earth, Energy & Environmental Sciences.
The Stanford study results were a major contributing factor in the recent decision by the Oklahoma Geological Survey (OGS) to issue a statement that said it was “very likely” that most of the state’s recent earthquakes are due to the injection of produced water into disposal wells that extend down to, or even beyond, the Arbuckle formation.
Before 2008, Oklahoma experienced one or two magnitude 4 earthquakes per decade, but in 2014 alone, the state experienced 24 such seismic events. Although the earthquakes are felt throughout much of the state, they pose little danger to the public, but scientists say that the possibility of triggering larger, potentially damaging earthquakes cannot be discounted.
In the study, Zoback and Walsh looked at three study areas-centered around the towns of Cherokee, Perry and Jones-in Oklahoma that have experienced the greatest number of earthquakes in recent years. All three areas showed clear increases in quakes following increases in wastetwater disposal. Three nearby control areas that did not have much wastewater disposal did not experience increases in the number of quakes.
Because the pair were also able to review data about the total amount of wastewater injected at wells, as well as the total amount of hydraulic fracturing happening in each study area, they were able to conclude that the bulk of the injected water was produced water generated using conventional oil extraction techniques, not during hydraulic fracturing.
“We know that some of the produced water came from wells that were hydraulically fractured, but in the three areas of most seismicity, over 95 percent of the wastewater disposal is produced water, not hydraulic fracturing flowback water,” said Zoback, who is also a senior fellow at Stanford’s Precourt Institute for Energy and director of the university’s recently launched Natural Gas Initiative, which is focused on ensuring that natural gas is developed and used in ways that are economically, environmentally, and societally optimal.
Time delay explained
The three study areas in Oklahoma that Zoback and Walsh looked at all showed a time delay between peak injection rate and the onset of seismicity, as well as spatial separations between the epicenter of the quakes and the injection well sites. Some of the quakes occurred months or even years after injection rates peaked and in locations that were sometimes located miles away from any wells.
These discrepancies had previously puzzled scientists, and had even been used by some to argue against a link between wastewater disposal and triggered earthquakes, but Zoback said they are easily explained by a simple conceptual model for Oklahoma’s seismicity that his team has developed.
According to this model, wastewater disposal is increasing the pore pressure in the Arbuckle formation, the disposal zone that sits directly above the crystalline basement, the rock layer where earthquake faults lie. Pore pressure is the pressure of the fluids within the fractures and pore spaces of rocks at depth. The earth’s crust contains many pre-existing faults, some of which are geologically active today. Shear stress builds up slowly on these faults over the course of geologic time, until it finally overcomes the frictional strength that keeps the two sides of a fault clamped together. When this happens, the fault slips, and energy is released as an earthquake.
Active faults in Oklahoma might trigger an earthquake every few thousand years. However, by increasing the fluid pressure through disposal of wastewater into the Arbuckle formation in the three areas of concentrated seismicity-from about 20 million barrels per year in 1997 to about 400 million barrels per year in 2013-humans have sped up this process dramatically. “The earthquakes in Oklahoma would have happened eventually,” Walsh said. “But by injecting water into the faults and pressurizing them, we’ve advanced the clock and made them occur today.”
Moreover, because pressure from the wastewater injection is spreading throughout the Arbuckle formation, it can affect faults located far from well sites, creating the observed time delay. “You can easily imagine that if a fault wasn’t located directly beneath a well, but several miles away, it would take time for the fluid pressure to propagate,” Walsh said.
Possible solutions
Now that the source of the recent quakes in Oklahoma is known, scientists and regulators can work on ways to stop them. One possible solution, Zoback said, would be cease injection of produced water into the Arbuckle formation entirely, and instead inject it back into producing formations such as the Mississippian Lime, an oil-rich limestone layer where much of the produced water in Oklahoma comes from in the first place.
Some companies already reinject water back into reservoirs in order to displace remaining oil and make it easier to recover. The Stanford study found that this technique, called enhanced oil recovery, does not result in increased earthquakes.
Even if companies opt to use producing formations to store wastewater, however, the quakes won’t cease immediately. “They’ve already injected so much water that the pressure is still spreading throughout the Arbuckle formation,” Zoback said. “The earthquakes won’t stop overnight, but they should subside over time.”
Reference:
F. Rall Walsh III and Mark D. Zoback. Oklahoma’s recent earthquakes and saltwater disposal. Science Advances, 2015 DOI: 10.1126/sciadv.1500195
A new study ties high-rate injection wells like this salt water disposal well in Colorado to enormous earthquake increase. Credit: Bill Ellsworth, USGS
A dramatic increase in the rate of earthquakes in the central and eastern U.S. since 2009 is associated with fluid injection wells used in oil and gas development, says a new study by the University of Colorado Boulder and the U.S. Geological Survey.
The number of earthquakes associated with injection wells has skyrocketed from a handful per year in the 1970s to more than 650 in 2014, according to CU-Boulder doctoral student Matthew Weingarten, who led the study. The increase included several damaging quakes in 2011 and 2012 ranging between magnitudes 4.7 and 5.6 in Prague, Oklahoma; Trinidad, Colorado; Timpson, Texas; and Guy, Arkansas.
“This is the first study to look at correlations between injection wells and earthquakes on a broad, nearly national scale,” said Weingarten of CU-Boulder’s geological sciences department. “We saw an enormous increase in earthquakes associated with these high-rate injection wells, especially since 2009, and we think the evidence is convincing that the earthquakes we are seeing near injection sites are induced by oil and gas activity.”
A paper on the subject appears in the June 18 issue of Science.
The researchers found that “high-rate” injection wells — those pumping more than 300,000 barrels of wastewater a month into the ground — were much more likely to be associated with earthquakes than lower-rate injection wells. Injections are conducted either for enhanced oil recovery, which involves the pumping of fluid into depleted oil reservoirs to increase oil production, or for the disposal of salty fluids produced by oil and gas activity, said Weingarten.
Co-authors on the study include CU-Boulder Professor Shemin Ge of the geological sciences department and Jonathan Godt, Barbara Bekins and Justin Rubinstein of the U.S. Geological Survey (USGS). Godt is based in Denver and Bekins and Rubenstein are based in Menlo Park, California.
The team assembled a database of roughly 180,000 injection wells in the study area, which ranged from Colorado to the East Coast. More than 18,000 wells were associated with earthquakes — primarily in Oklahoma and Texas — and 77 percent of associated injection wells remain active, according to the study authors.
Of the wells associated with earthquakes, 66 percent were oil recovery wells, said Ge. But active saltwater disposal wells were 1.5 times as likely as oil recovery wells to be associated with earthquakes. “Oil recovery wells involve an input of fluid to ‘sweep’ oil toward a second well for removal, while wastewater injection wells only put fluid into the system, producing a larger pressure change in the reservoir,” Ge said.
Enhanced oil recovery wells differ from hydraulic fracturing, or fracking wells, in that they usually inject for years or decades and are operated in tandem with conventional oil production wells, said Weingarten. In contrast, fracking wells typically inject for just hours or days.
The team noted that thousands of injection wells have operated during the last few decades in the central and eastern U.S. without a ramp-up in seismic events. “It’s really the wells that have been operating for a relatively short period of time and injecting fluids at high rates that are strongly associated with earthquakes,” said Weingarten.
In addition to looking at injection rates of individual wells over the study area, the team also looked at other aspects of well operations including a well’s cumulative injected volume of fluid over time, the monthly injection pressure at individual wellheads, the injection depth, and their proximity to “basement rock” where earthquake faults may lie. None showed significant statistical correlation to seismic activity at a national level, according to the study.
Oklahoma had the most seismic activity of any state associated with wastewater injection wells. But parts of Colorado, west Texas, central Arkansas and southern Illinois also showed concentrations of earthquakes associated with such wells, said Weingarten.
In Colorado, the areas most affected by earthquakes associated with injection wells were the Raton Basin in the southern part of the state and near Greeley north of Denver.
“People can’t control the geology of a region or the scale of seismic stress,” Weingarten said. “But managing rates of fluid injection may help decrease the likelihood of induced earthquakes in the future.”
The study was supported by the USGS John Wesley Powell Center for Analysis and Synthesis, which provides opportunities for collaboration between government, academic and private sector scientists.
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Reference:
M. Weingarten, S. Ge, J. W. Godt, B. A. Bekins, J. L. Rubinstein. High-rate injection is associated with the increase in U.S. mid-continent seismicity. Science, 2015 DOI: 10.1126/science.aab1345
Jumping the shark. Credit: Dmitry Bogdanov, CC BY-SA
The release of Jurassic World has reignited our love for palaeontology. Many of us share a longing to understand the dinosaurs that roamed the Earth long before we arrived. But palaeontology is a discipline much broader than this.
Dinosaurs dominated the land for 135 million years, but what happened during the rest of the Earth’s 4.6 billion-year history? The role of palaeontologists past and present has been to unravel the mysteries of life on Earth, and in doing so they’ve found a lot more than just dinosaur bones.
Right side up? Credit: Natural Math/flickr, CC BY-SA
Hallucigenia was discovered when a 508 million year old fossil was found in 1911 in the world-famous Burgess Shale fossil site in Canada. Since then, our understanding of this ocean-dwelling creature has changed dramatically.
Its age means it falls into the geological Cambrian period, a pivotal moment for all life on Earth when complex lifeforms started to rapidly evolve. When originally described, Hallucigenia was first thought to have walked along the ocean floor on spiny legs and used tentacles on its back to catch food. Palaeontologists also argued over which end was its head.
But when a similar fossil was found in China, Hallucigenia was re-examined. Palaeontologists then discovered that its “legs” were actually protective spines on its back, and the tentacles formed two rows on its underside enabling it to “walk”. Researchers are still debating many of the features of Hallucigenia today, more than 100 years after it was discovered.
2. (Almost) the first fish out of water
Best foot forward. Credit: Nobu Tamura, CC BY-SA
100 million years on from Hallucigenia, aquatic habitats were thriving, but life on land was still in its earliest stages. Tiktaalik, part fish, part four-legged animal, is believed to be the first creature to develop characteristics that would help animals move out of the water and on to land.
It had gills, fins and scales like a fish, but also evolved features such as a flexible neck and a reptile-like head and lungs, beneficial for life on the ground. Fossils also show Tiktaalik had long fins that acted as legs, meaning it could “walk” along riverbeds as well as swim.
3. The giant Scottish scorpion
Sting in the tail. Credit: Nobu Tamura, CC BY
Pulmonoscorpius kirktonensis, a 70cm-long scorpion, lived in what we now know as Scotland 340 million years ago. At a length greater than that of the average pet cat, this terrifying creature used its tail to catch and kill its prey.
Pulmonoscorpius also had unusually large eyes compared to its modern relatives, so most likely hunted during daylight hours. Scorpions shed their skin as they grow, so fossils of both the skin and the animal itself have been found.
4. The spiral-lipped shark
Jumping the shark. Credit: Dmitry Bogdanov, CC BY-SA
Helicoprion, a shark-like fish alive during the Permian (290 million years ago), had a rather unique dental structure. With a face that baffled palaeontologists for years, this creature had a lower jaw made up of a spiral of teeth, known as a tooth-whorl.
Modern sharks are able to lose and replace their teeth, but Helicoprion kept them all, with older teeth hidden within the inner layers of the tooth-whorl. When it caught its prey (most likely relatives of the squid), it would close its mouth and rotate its tooth-whorl to shred its catch.
5. A tiny, drunk horse
Gone to that big horsey ring in the sky. Credit: Daderot
The Messel Oil Shale, once a volcanic lake in Germany, has plenty to offer the world of palaeontology. Eurohippus messelensis, was a miniature horse (the size of a modern day fox) originally thought to have died from eating fermented berries and in a drunken stupor, fallen into the lake. It’s now believed the 47 million year old horse actually died from inhaling toxic gas occasionally released from the depths of the lake.
But the misfortune continues, as it was later discovered that the horse was pregnant. Palaeontologists used high-resolution microscopes to identify the bones of a foal within the adult Eurohippus, improving our understanding of foetal development in these animals.
Palaeontology is a career firmly seated on many childhood wish-lists alongside movie stars and astronauts, and rightly so. But it’s important to remember there’s a lot more to palaeontology than the dinosaurs. This list is just the start.
Note: The above post is reprinted from materials provided by The Conversation. This story is published courtesy of The Conversation (under Creative Commons-Attribution/No derivatives).
Teeth of a 16-million-year-old bat discovered in New Zealand. Credit: Rod Morris
Fossilised remains of a new bat species, which lived 16 million years ago, walked on four limbs and was three times larger than today’s average bat, have been discovered in New Zealand.
The fossils were found near Central Otago on South Island, in sediment left over from a vast prehistoric body of water known as Lake Manuherikia, which was part of warmer subtropical rainforest during the early Miocene era, between 16 and 19-million-years-ago.
The new species, Mystacina miocenalis, was described today in the journal PLOS ONE, and is related to another bat, Mystacina tuberculata, which still lives in New Zealand’s old growth forests.
“Our discovery shows for the first time that Mystacina bats have been present in New Zealand for upwards of 16 million years, residing in habitats with very similar plant life and food sources,” says lead author and vertebrate palaeontologist, Associate Professor Suzanne Hand from the University of New South Wales (UNSW) in Australia.
New Zealand’s only native terrestrial mammals are three species of bat, including two belonging to the Mystacina genus – one of which was last sighted in the 1960s. They are known as burrowing bats because they forage on the ground under leaf-litter and snow, as well as in the air, scuttling on their wrists and backward-facing feet, while keeping their wings tightly furled.
These bats were believed to have an ancient history in New Zealand, but until now, the oldest fossil of a Mystacina bat in New Zealand was from a cave in South Island, dating to 17,500 years ago. This latest discovery forces a rethink of when these peculiar, walking bats first crossed the ditch, arriving from what is present-day Australia.
“This helps us understand the capacity of bats to establish populations on islands and the climatic conditions required for this to happen,” says Associate Professor Hand.
“Bats are important pollinators and seed dispersers that keep forests healthy. Understanding the connectivity between the bat faunas of different landmasses is important for evaluating biosecurity threats and conservation priorities for fragile island ecosystems.”
The new species has similar teeth to its contemporary relative, suggesting a broad diet that included nectar, pollen and fruit, as well as insects and spiders. Limb bones found in the deposit also showed similar structures specialised for walking.
Where they differ is body size: at an estimated 40 grams, the fossil bat is roughly three times heavier than its living cousin, and the average weight of more than 900 living bat species.
“The size of bats is physically constrained by the demands of flight and echolocation, as you need to be small, quick and accurate to chase insects in the dark,” explains Associate Professor Hand. “The unusually large size of this bat suggests it was doing less in-flight hunting and was taking heavier prey from the ground, and larger fruit than even its living cousin.”
The team also found a diverse array of plant, animal and insect fossils at the site, which shows that the 16-million-year-old subtropical ecosystem bore resemblance to the more temperate one that exists today.
“Remarkably, the Miocene ecosystems associated with the fossil bat contain the kinds of trees used today by Mystacina for its colonial roosts,” says Associate Professor Hand. “Most of its food plants are also represented, as are terrestrial arthropods including a variety of beetles, ants and spiders, which these bats continue to hunt on the ground.”
The Lake Manuherikia site has been a treasure trove for palaeontologists over the years, producing New Zealand’s oldest frogs, lizards and land birds, as well as its only crocodiles and terrestrial turtles.
Reference:
Suzanne J. Hand, Daphne E. Lee, Trevor H. Worthy, Michael Archer, Jennifer P. Worthy, Alan J. D. Tennyson, Steven W. Salisbury, R. Paul Scofield, Dallas C. Mildenhall, Elizabeth M. Kennedy, Jon K. Lindqvist. Miocene Fossils Reveal Ancient Roots for New Zealand’s Endemic Mystacina (Chiroptera) and Its Rainforest Habitat. PLOS ONE, 17 Jun 2015 DOI: 10.1371/journal.pone.0128871
Inside the head of the worm C. elegans, the TV antenna-like structure at the tip of the AFD neuron (green) is the first identified sensor for Earth’s magnetic field. Credit: Illustration by Andres Vidal-Gadea.
A team of scientists and engineers at The University of Texas at Austin has identified the first sensor of Earth’s magnetic field in an animal, finding in the brain of a tiny worm a big clue to a long-held mystery about how animals’ internal compasses work.
Animals as diverse as migrating geese, sea turtles and wolves are known to navigate using Earth’s magnetic field. But until now, no one has pinpointed quite how they do it. The sensor, found in worms called C. elegans, is a microscopic structure at the end of a neuron that other animals probably share, given similarities in brain structure across species. The sensor looks like a nano-scale TV antenna, and the worms use it to navigate underground.
“Chances are that the same molecules will be used by cuter animals like butterflies and birds,” said Jon Pierce-Shimomura, assistant professor of neuroscience in the College of Natural Sciences and member of the research team. “This gives us a first foothold in understanding magnetosensation in other animals.”
The researchers discovered that hungry worms in gelatin-filled tubes tend to move down, a strategy they might use when searching for food.
When the researchers brought worms into the lab from other parts of the world, the worms didn’t all move down. Depending on where they were from — Hawaii, England or Australia, for example — they moved at a precise angle to the magnetic field that would have corresponded to down if they had been back home. For instance, Australian worms moved upward in tubes. The magnetic field’s orientation varies from spot to spot on Earth, and each worm’s magnetic field sensor system is finely tuned to its local environment, allowing it to tell up from down.
The research is published today in the journal eLife.
The study’s lead author is Andrés Vidal-Gadea, a former postdoctoral researcher in the College of Natural Sciences at UT Austin, now a faculty member at Illinois State University. He noted that C. elegans is just one of myriad species living in the soil, many of which are known to migrate vertically.
“I’m fascinated by the prospect that magnetic detection could be widespread across soil dwelling organisms,” said Vidal-Gadea.
The neuroscientists and engineers, who use C. elegans in their research into Alzheimer’s disease and addiction, had previously discovered the worm’s ability to sense humidity. That work led them to ask what else the worms might be able to sense, such as magnetic fields.
In 2012, scientists from Baylor College of Medicine announced the discovery of brain cells in pigeons that process information about magnetic fields, but they did not discover which part of the body senses the fields. That team and others have proposed a magnetosensor in the birds’ inner ear.
“It’s been a competitive race to find the first magnetosensory neuron,” said Pierce-Shimomura. “And we think we’ve won with worms, which is a big surprise because no one suspected that worms could sense the Earth’s magnetic field.”
The neuron sporting a magnetic field sensor, called an AFD neuron, was already known to sense carbon dioxide levels and temperature.
The researchers discovered the worms’ magnetosensory abilities by altering the magnetic field around them with a special magnetic coil system and then observing changes in behavior. They also showed that worms which were genetically engineered to have a broken AFD neuron did not orient themselves up and down as do normal worms. Finally, the researchers used a technique called calcium imaging to demonstrate that changes in the magnetic field cause the AFD neuron to activate.
Pierce-Shimomura suggested this research might open up the possibility of manipulating magnetic fields to protect agricultural crops from harmful pests.Other members of the research team from the College of Natural Sciences are Joshua Russell, a former graduate student who completed his Ph.D.; Kristi Ward, a former undergraduate; and Celia Beron, a current undergraduate. Research team members from the Cockrell School of Engineering are: Dr. Adela Ben-Yakar, associate professor of mechanical engineering; Navid Ghorashian, a former graduate student who completed his Ph.D.; and Sertan Gokce, a current graduate student.
Support for this research came from the National Institutes of Health and the National Institute of Neurological Disorders and Stroke.
Less oxygen dissolved in the water is often referred to as a “dead zone” (in red above) because most marine life either dies, or, if they are mobile such as fish, leave the area. Habitats that would normally be teeming with life become, essentially, biological deserts. Credit: NOAA
Scientists are expecting a very large “dead zone” in the Gulf of Mexico and a smaller than average hypoxic level in the Chesapeake Bay this year, based on several NOAA-supported forecast models.
NOAA-supported modelers at the University of Michigan, Louisiana State University, and the Louisiana Universities Marine Consortium are forecasting that this year’s Gulf of Mexico hypoxic “dead” zone will be between 7,286 and 8,561 square miles which could place it among the ten largest recorded. That would range from an area the size of Connecticut, Rhode Island and the District of Columbia combined on the low end to the New Jersey on the upper end. The high estimate would exceed the largest ever reported 8,481 square miles in 2002 .
Hypoxic (very low oxygen) and anoxic (no oxygen) zones are caused by excessive nutrient pollution, often from human activities such as agriculture, which results in insufficient oxygen to support most marine life in near-bottom waters. Aspects of weather, including wind speed, wind direction, precipitation and temperature, also impact the size of dead zones.
The Gulf estimate is based on the assumption of no significant tropical storms in the two weeks preceding or during the official measurement survey cruise scheduled from July 25-August 3 2013. If a storm does occur the size estimate could drop to a low of 5344 square miles, slightly smaller than the size of Connecticut.
This year’s prediction for the Gulf reflect flood conditions in the Midwest that caused large amounts of nutrients to be transported from the Mississippi watershed to the Gulf. Last year’s dead zone in the Gulf of Mexico was the fourth smallest on record due to drought conditions, covering an area of approximately 2,889 square miles, an area slightly larger than the state of Delaware. The overall average between 1995-2012 is 5,960 square miles, an area about the size of Connecticut.
A second NOAA-funded forecast, for the Chesapeake Bay, calls for a smaller than average dead zone in the nation’s largest estuary. The forecasts from researchers at the University of Maryland Center for Environmental Science and the University of Michigan has three parts: a prediction for the mid-summer volume of the low-oxygen hypoxic zone, one for the mid-summer oxygen-free anoxic zone, and a third that is an average value for the entire summer season.
The forecasts call for a mid-summer hypoxic zone of 1.46 cubic miles, a mid-summer anoxic zone of 0.26 to 0.38 cubic miles, and a summer average hypoxia of 1.108 cubic miles, all at the low end of previously recorded zones. Last year the final mid-summer hypoxic zone was 1.45 cubic miles.
This is the seventh year for the Bay outlook which, because of the shallow nature of large areas of the estuary, focuses on water volume or cubic miles, instead of square mileage as used in the Gulf. The history of hypoxia in the Chesapeake Bay since 1985 can be found at the EcoCheck website.
Both forecasts are based on nutrient run-off and river stream data from the U.S. Geological Survey (USGS), with the Chesapeake data funded with a cooperative agreement between USGS and the Maryland Department of Natural Resources. Those numbers are then inserted into models developed by funding from the National Ocean Service’s National Centers for Coastal Ocean Science (NCCOS).
“Monitoring the health and vitality of our nation’s oceans, waterways, and watersheds is critical as we work to preserve and protect coastal ecosystems,” said Kathryn D. Sullivan, Ph.D., acting under secretary of commerce for oceans and atmosphere and acting NOAA administrator. “These ecological forecasts are good examples of the critical environmental intelligence products and tools that help shape a healthier coast, one that is so inextricably linked to the vitality of our communities and our livelihoods.”
The dead zone in the Gulf of Mexico affects nationally important commercial and recreational fisheries, and threatens the region’s economy. The Chesapeake dead zones, which have been highly variable in recent years, threaten a multi-year effort to restore the Bay’s water quality and enhance its production of crabs, oysters, and other important fisheries.
During May 2013, stream flows in the Mississippi and Atchafalaya rivers were above normal resulting in more nutrients flowing into the Gulf. According to USGS estimates, 153,000 metric tons of nutrients flowed down the rivers to the northern Gulf of Mexico in May, an increase of 94,900 metric tons over last year’s 58,100 metric tons, when the region was suffering through drought. The 2013 input is an increase of 16 percent above the average nutrient load estimated over the past 34 years.
For the Chesapeake Bay, USGS estimates 36,600 metric tons of nutrients entered the estuary from the Susquehanna and Potomac rivers between January and May, which is 30 percent below the average loads estimated from1990 to 2013.
“Long-term nutrient monitoring and modeling is key to tracking how nutrient conditions are changing in response to floods and droughts and nutrient management actions,” said Lori Caramanian, deputy assistant secretary of the interior for water and science. “Understanding the sources and transport of nutrients is key to developing effective nutrient management strategies needed to reduce the size of hypoxia zones in the Gulf, Bay and other U.S. waters where hypoxia is an on-going problem.”
“Coastal hypoxia is proliferating around the world,” said Donald Boesch, Ph.D., president of the University of Maryland Center for Environmental Science. “It is important that we have excellent abilities to predict and control the largest dead zones in the United States. The whole world is watching.”
The confirmed size of the 2013 Gulf hypoxic zone will be released in August, following a monitoring survey led by the Louisiana Universities Marine Consortium beginning in late July, and the result will be used to improve future forecasts. The final measurement in the Chesapeake will come in October following surveys by the Chesapeake Bay Program’s partners from the Maryland Department of Natural Resources and the Virginia Department of Environmental Quality.
Despite the Mississippi River/Gulf of Mexico Nutrient Task Force’s goal to reduce the dead zone to less than 2,000 square miles, it has averaged 5,600 square miles over the last five years. Demonstrating the link between the dead zone and nutrients from the Mississippi River, this annual forecast continues to provide guidance to federal and state agencies as they work on the 11 implementation actions outlined by the Task Force in 2008 for mitigating nutrient pollution.
NOAA’s National Ocean Service has been funding investigations and forecast development for the dead zone in the Gulf of Mexico since 1990, and oversees national hypoxia research programs which include the Chesapeake Bay and other affected bodies of water.
USGS operates more than 3,000 real-time stream gages and collects water quality data at numerous long-term stations throughout the Mississippi River basin and the Chesapeake Bay to track how nutrient loads are changing over time.
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Note: The above post is reprinted from materials provided by NOAA.
So perhaps there is some truth in the old legends of the underworld reeking of brimstone (or sulphur, as it is now called)? New research confirms that the Earth’s core does in fact contain vast amounts of sulphur, estimated to be up to 8.5 x 1018 tonnes. This is about 10 times the amount of sulphur in the rest of the Earth, based on the most recent estimates (and for comparison, around 10% of the total mass of the Moon). This is the first time that scientists have conclusive geochemical evidence for sulphur in the Earth’s core, lending weight to the theory that the Moon was formed by a planet-sized body colliding with the Earth. This work is reported in the peer-reviewed journal, Geochemical Perspectives Letters.
The Earth’s core begins 2900km beneath our feet, so it is impossible to investigate directly. However, an international group of researchers have been able to develop indirect geochemical methods to show core composition.
As lead researcher Dr Paul Savage (Department of Earth Sciences, Durham University, UK) said:
“Scientists have suspected that there is sulphur in the core for some time, but this is the first time we have solid geochemical evidence to support the idea.”
For a long time it has been known that the Earth’s core is too light to be made only of iron and nickel, and it had been assumed that the core contained other lighter elements, such as sulphur, silicon, oxygen and carbon. However, given the depth of the core, this has been impossible to confirm directly. Fortunately, a cataclysmic event in the distant past – when the Earth collided with a large, planet-sized body, tearing off the part which became our Moon – left a fingerprint, which has been used to confirm the core content.
The researchers believe that the impact of the collision melted the Earth’s mantle, allowing a sulphur-rich liquid to form in Earth’s mantle, the vast middle layer between the core and the crust; some was probably lost into space, but some remained and sunk into the core. The key to confirming this lay in measuring the isotope ratios of elements (isotopes are atoms of the same element with slightly different masses) in the mantle, and comparing these to certain meteorites, which are believed to be the best match to the Earth’s original composition.
Because of variability in mantle composition, it is difficult to draw firm conclusions from measuring sulphur directly, so the researchers chose to analyse copper from the Earth’s mantle and crust – copper is often bound to sulphur. “We chose copper, because it is a chalcophile element, which means it prefers to be in sulphide-rich material – so is a good element to trace the fate of sulphur on Earth,” said senior author Professor Frédéric Moynier (Institut de Physique du Globe, Paris). “Generally, where there is copper, there is sulphur; copper gives us a proxy measurement for sulphur.”
The work comprised 3 distinct stages:
Firstly, the researchers had to estimate the isotopic composition of copper in the Earth’s mantle and crust.
Secondly, they had to estimate the isotopic composition of copper in the Earth before it formed a core, and was bombarded by giant impactors. Direct measurement is of course impossible, so they used meteorites, which are regarded as the best analogue.
Finally, they had to simulate which copper isotopic signature would be generated by the removal of sulphur-rich liquid after the ‘giant impact’.
Using the state-of-the-art mass spectroscopes at the Washington University in St. Louis and the Institut de Physique du Globe, Paris, they were able to confirm that there was a difference of 0.025% in the copper isotopic ratios between the Earth mantle samples, and the meteorite samples. Because the isotopes of copper divide unevenly between a sulphur-rich liquid and the rest of Earth’s mantle, this shows that a large amount of sulphur must have been removed from the mantle.
Paul Savage said:
“This study is the first to show clear geochemical evidence that a sulphide liquid must have separated from the mantle early on in Earth’s history – which most likely entered the core. We estimate that the quantity of sulphur in the core is vast, around 8.5 x 1018 tonnes, which to give an idea of scale, is around 10% of the mass of the Moon. In addition, the work adds weight to the theory that the Moon was formed via a collision between the Earth and another body.
“In a way, we can also say that we have life imitating art. For millennia, tales have been told of the underworld being awash with fire and brimstone. Now at least, we can be sure of the brimstone.”
Commenting, Executive Co-Editor of Geochemical Perspectives Letters, Professor Graham Pearson (University of Alberta) said:
“The presence and identity of other elements in the Earth’s core has been one of the most enduring problems in geochemistry. Savage and colleagues provide very elegant evidence, using isotopes of copper as a tracer, of the stripping of vast amounts of sulphur from the Earth’s early mantle into the core. So the core turns out to be a good place to hide quite substantial amounts of elements other than iron and nickel. This study will surely encourage others to persist in the search for evidence of other elements in the core – data that is critically needed to complete our understanding of how the Earth formed and what the geochemical mass balance is in the Earth.”
Reference:
Copper isotope evidence for large-scale sulphide fractionation during Earth’s differentiation, Geochemical Perspectives Letters, v1, n1 , DOI: 10.7185/geochemlet.1506
A discovery by James Cook University researchers means evidence from the past could be used to help predict the danger of earthquakes in less-developed countries.
Lead researcher Hannah Hilbert-Wolf and supervisor Dr Eric Roberts used innovative methods to examine the ground around Mbeya in Tanzania where a large earthquake occurred some 25,000 years ago.
They found evidence of fluidisation (where soil behaves like quicksand) and upward displacement of material unprecedented in a continental setting, raising questions of how resilient the rapidly growing cities of the region would be in a major shake.
“We can now use this to evaluate how the ground would deform in a modern earthquake,” said Dr Roberts. “This is important because the approach is inexpensive and can be used to model how structures might be affected by future events, providing a valuable tool in hazard assessment.”
Ms Hilbert-Wolf said the team found evidence of massive ground deformation and previously unknown styles of liquefaction and fluidisation, caused by past earthquakes. “This could be a major concern for the growing urban population of East Africa, which has similar tectonic settings and surface conditions,” she said.
The study comes on the back of a series of damaging earthquakes already this year, including in Nepal and Papua New Guinea and the study may be of much use in predicting the effects of earthquakes in those countries.
“What we have shown is that in developing countries in particular, which may lack extensive seismic monitoring, the rock record can be used to not only investigate the timing and frequency of past events, but also provide important insights into how the ground will behave in certain areas to seismic shock,” said Ms Hilbert-Wolf.
In 1910, 7.5 million people lived in Tanzania when the most powerful earthquake in Africa of the twentieth century struck, collapsing houses and triggering liquefaction and fluidisation. By 2050 it is estimated that around 130 million people will live in Tanzania, mostly in constructed urban settings that are more susceptible to earthquake damage and surface deformation than traditionally fabricated buildings.
Reference:
Hannah Louise Hilbert-Wolf, Eric M. Roberts. Giant Seismites and Megablock Uplift in the East African Rift: Evidence for Late Pleistocene Large Magnitude Earthquakes. PLOS ONE, 2015; 10 (6): e0129051 DOI: 10.1371/journal.pone.0129051
UC Irvine researchers used NASA satellites to show aquifer depletion worldwide. They are trying to raise awareness about the lack of information about remaining groundwater supplies on Earth Credit: UC Irvine / NASA
Two new studies led by UC Irvine using data from NASA Gravity Recovery and Climate Experiment satellites show that civilization is rapidly draining some of its largest groundwater basins, yet there is little to no accurate data about how much water remains in them.
The result is that significant segments of Earth’s population are consuming groundwater quickly without knowing when it might run out, the researchers conclude. The findings appear today in Water Resources Research.
“Available physical and chemical measurements are simply insufficient,” said UCI professor and principal investigator Jay Famiglietti, who is also the senior water scientist at NASA’s Jet Propulsion Laboratory. “Given how quickly we are consuming the world’s groundwater reserves, we need a coordinated global effort to determine how much is left.”
The studies are the first to characterize groundwater losses via data from space, using readings generated by NASA’s twin GRACE satellites that measure dips and bumps in Earth’s gravity, which is affected by the weight of water.
For the first paper, researchers examined the planet’s 37 largest aquifers between 2003 and 2013. The eight worst off were classified as overstressed, with nearly no natural replenishment to offset usage. Another five aquifers were found, in descending order, to be extremely or highly stressed, depending upon the level of replenishment in each — still in trouble but with some water flowing back into them.
The most overburdened are in the world’s driest areas, which draw heavily on underground water. Climate change and population growth are expected to intensify the problem.
“What happens when a highly stressed aquifer is located in a region with socioeconomic or political tensions that can’t supplement declining water supplies fast enough?” asked the lead author on both studies, Alexandra Richey, who conducted the research as a UCI doctoral student. “We’re trying to raise red flags now to pinpoint where active management today could protect future lives and livelihoods.”
The research team — which included co-authors from NASA, the National Center for Atmospheric Research, National Taiwan University and UC Santa Barbara — found that the Arabian Aquifer System, an important water source for more than 60 million people, is the most overstressed in the world.
The Indus Basin aquifer of northwestern India and Pakistan is the second-most overstressed, and the Murzuk-Djado Basin in northern Africa is third. California’s Central Valley, utilized heavily for agriculture and suffering rapid depletion, was slightly better off but still labeled highly stressed in the first study.
“As we’re seeing in California right now, we rely much more heavily on groundwater during drought,” Famiglietti said. “When examining the sustainability of a region’s water resources, we absolutely must account for that dependence.”
In a companion paper published today in the same journal, the scientists conclude that the total remaining volume of the world’s usable groundwater is poorly known, with often widely varying estimates, but is likely far less than rudimentary estimates made decades ago.
By comparing their satellite-derived groundwater loss rates to what little data exists on groundwater availability, they found major discrepancies in projected “time to depletion.” In the overstressed Northwest Sahara Aquifer System, for example, this fluctuated between 10 and 21,000 years.
“We don’t actually know how much is stored in each of these aquifers. Estimates of remaining storage might vary from decades to millennia,” Richey said. “In a water-scarce society, we can no longer tolerate this level of uncertainty, especially since groundwater is disappearing so rapidly.”
The study notes that the dearth of groundwater is already leading to significant ecological damage, including depleted rivers, declining water quality and subsiding land.
Groundwater aquifers are typically located in soil or deeper rock layers beneath Earth’s surface. The depth and thickness of many make it tough and costly to drill to or otherwise reach bedrock and learn where the moisture bottoms out. But it has to be done, according to the authors.
“I believe we need to explore the world’s aquifers as if they had the same value as oil reserves,” Famiglietti said. “We need to drill for water the same way that we drill for other resources.”
References:
Alexandra S. Richey, Brian F. Thomas, Min-Hui Lo, James S. Famiglietti, Sean Swenson, Matthew Rodell. Uncertainty in global groundwater storage estimates in a total groundwater stress framework. Water Resources Research, 2015; DOI: 10.1002/2015WR017351
Alexandra S. Richey, Brian F. Thomas, Min-Hui Lo, John T. Reager, James S. Famiglietti, Katalyn Voss, Sean Swenson, Matthew Rodell. Quantifying renewable groundwater stress with GRACE. Water Resources Research, 2015; DOI: 10.1002/2015WR017349
Scientists found methane gas in samples taken from Martian meteorites. Credit: Image by Michael Helfenbein
An international team of researchers has discovered traces of methane in Martian meteorites, a possible clue in the search for life on the Red Planet.
The researchers examined samples from six meteorites of volcanic rock that originated on Mars. The meteorites contain gases in the same proportion and with the same isotopic composition as the Martian atmosphere. All six samples also contained methane, which was measured by crushing the rocks and running the emerging gas through a mass spectrometer. The team also examined two non-Martian meteorites, which contained lesser amounts of methane.
The discovery hints at the possibility that methane could be used as a food source by rudimentary forms of life beneath the Martian surface. On Earth, microbes do this in a range of environments.
“Other researchers will be keen to replicate these findings using alternative measurement tools and techniques,” said co-author Sean McMahon, a Yale University postdoctoral associate in the Department of Geology and Geophysics. “Our findings will likely be used by astrobiologists in models and experiments aimed at understanding whether life could survive below the surface of Mars today.”
The discovery was part of a joint research project led by the University of Aberdeen, in collaboration with the Scottish Universities Environmental Research Centre, the University of Glasgow, Brock University in Ontario, and the University of Western Ontario.
“One of the most exciting developments in the exploration of Mars has been the suggestion of methane in the Martian atmosphere,” said University of Aberdeen professor John Parnell, who directed the research. “Recent and forthcoming missions by NASA and the European Space Agency, respectively, are looking at this, however, it is so far unclear where the methane comes from, and even whether it is really there. However, our research provides a strong indication that rocks on Mars contain a large reservoir of methane.”
Co-author Nigel Blamey, of Brock University, said the team plans to expand its research by analyzing additional meteorites.
Yale’s McMahon noted that the team’s approach may prove helpful in future Mars rover experiments. “Even if Martian methane does not directly feed microbes, it may signal the presence of a warm, wet, chemically reactive environment where life could thrive,” McMahon said.
Reference:
Nigel J. F. Blamey, John Parnell, Sean McMahon, Darren F. Mark, Tim Tomkinson, Martin Lee, Jared Shivak, Matthew R. M. Izawa, Neil R. Banerjee, Roberta L. Flemming. Evidence for methane in Martian meteorites. Nature Communications, 2015; 6: 7399 DOI: 10.1038/ncomms8399
Note: The above post is reprinted from materials provided by Yale University. The original item was written by Jim Shelton.
Sign at shuttered uranium mill in Rifle, Colorado, warns onlookers of hazards that remain from Cold War era nuclear weapons production. Credit: Bill Gillette, U.S. National Archives and Records Administration
A strain of bacteria that “breathes” uranium may hold the key to cleaning up polluted groundwater at sites where uranium ore was processed to make nuclear weapons.
A team of Rutgers University scientists and collaborators discovered the bacteria in soil at an old uranium ore mill in Rifle, Colorado, almost 200 miles west of Denver. The site is one of nine such mills in Colorado used during the heyday of nuclear weapons production.
The research is part of a U.S. Department of Energy program to see if microorganisms can lock up uranium that leached into the soil years ago and now makes well water in the area unsafe to drink.
The team’s discovery, published in the April 13, 2015 issue of PLOS ONE, is the first known instance where scientists have found a bacterium from a common class known as betaproteobacteria that breathes uranium. This bacterium can breathe either oxygen or uranium to drive the chemical reactions that provide life-giving energy.
“After the newly discovered bacteria interact with uranium compounds in water, the uranium becomes immobile,” said Lee Kerkhof, a professor of marine and coastal sciences in the School of Environmental and Biological Sciences. “It is no longer dissolved in the groundwater and therefore can’t contaminate drinking water brought to the surface.”
Kerkhof leads the Rutgers team that works with U.S. Department of Energy researchers.
Breathing uranium is rather rare in the microbial world. Most examples of bacteria which can respire uranium cannot breathe oxygen but often breathe compounds based on metals – typically forms of solid iron. Scientists had previously witnessed decreasing concentrations of uranium in groundwater when iron-breathing bacteria were active, but they have yet to show that those iron-breathing bacteria were directly respiring the uranium.
While the chemical reaction that the bacteria perform on uranium is a common process known as “reduction,” or the act of accepting electrons, Kerkhof said it’s still a mystery how the reduced uranium produced by this microorganism ultimately behaves in the subsurface environment.
“It appears that they form uranium nanoparticles,” he said, but the mineralogy is still not well known and will be the subject of ongoing research.
The Rutgers team was able to isolate the uranium-breathing bacterium in the lab by recognizing that uranium in samples from the Rifle site could be toxic to microorganisms as well as humans. The researchers looked for signs of bacterial activity when they gradually added small amounts of dissolved uranium at the right concentration back to the samples where uranium had become immobilized. Once they found the optimal uranium concentrations, they were able to isolate the novel strain.
Exactly how the strain evolved, Kerkhof said, “we are not sure.” But, he explained, bacteria have the ability to pass genes to each other. So just like bacteria pick up resistance to things like antibiotics and heavy metal toxicity, this bacterium “picked up a genetic element that’s now allowing it to detoxify uranium, to actually grow on uranium.” His research team has completed sequencing its genome to support future research into the genetic elements that allow the bacterium to grow on uranium.
What Kerkhof is optimistic about is the potential for these bacteria to mitigate the specific groundwater pollution problem in Rifle. Scientists at first expected the groundwater to flush into the Colorado River and carry the dissolved uranium with it, where it would get diluted to safer levels. But that hasn’t happened. Other potential methods of remediation, such as digging up the contaminated soil or treating it with harsh chemicals, are thought to be too expensive or hazardous.
“Biology is a way to solve this contamination problem, especially in situations like this where the radionuclides are highly diluted but still present at levels deemed hazardous,” said Kerkhof. If the approach is successful, it could be considered for other sites where uranium was processed for nuclear arsenals or power plant fuel. While the problem isn’t widespread, he said there’s potentially a lot of water to be concerned about. And the problem could spread beyond traditional places such as ore processing sites.
“There is depleted uranium in a lot of armor-piercing munitions,” he said, “so places like the Middle East that are experiencing war could be exposed to high levels of uranium in the groundwater.”
Reference:
Nicole M. Koribanics, Steven J. Tuorto,Nora Lopez-Chiaffarelli, Lora R. McGuinness,Max M. Häggblom, Kenneth H. Williams, Philip E. Long,Lee J. Kerkhof. Spatial Distribution of an Uranium-Respiring Betaproteobacterium at the Rifle, CO Field Research Site. DOI: 10.1371/journal.pone.0123378
