This image shows the skull and skeleton of Iberian Worm Lizard, (Blanus). Credit: Nick Longrich
Tiny, burrowing reptiles known as worm lizards became widespread long after the breakup of the continents, leading scientists to conclude that they must have dispersed by rafting across oceans soon after the extinction of the dinosaurs, rather than by continental drift as previously thought.
Scientists at the Universities of Bath, Bristol, Yale University and George Washington University used information from fossils and DNA from living species to create a molecular clock to give a more accurate timescale of when the different species split apart from each other.
The team studied fossils of worm lizards (Amphisbaenia), a type of burrowing lizards that live almost exclusively underground. The six families of worm lizards are found in five different continents, puzzling biologists as to how these creatures became so widespread.
They found that the worm lizards evolved rapidly and expanded to occupy new habitats around 65 million years ago, just after the impact of an asteroid that caused the mass extinction of around 75 per cent of living things on Earth, including the dinosaurs.
Since this event occurred after the break-up of the super-continent Pangaea, the researchers conclude that these animals could not have dispersed across the globe using land bridges.
Instead they argue that this evidence supports a theory proposed by Charles Darwin and Alfred Russell Wallace in the 19th Century that creatures crossed from continent to continent crossing land bridges or floating across oceans — in this case being carried across the oceans on floating vegetation.
Dr Nick Longrich, from the University of Bath, explained: “Continental drift clearly can’t explain the patterns we’re seeing. Continental breakup was about 95 million years ago, and these animals only become widespread 30 million years later.
“It seems highly improbable not only that enough of these creatures could have survived a flood clinging to the roots of a fallen tree and then travelled hundreds of miles across an ocean, but that they were able to thrive and flourish in their new continent.
“But having looked at the data, it is the only explanation for the remarkable diversity and spread of not just worm lizards, but nearly every other living thing as well.
“Once you eliminate the impossible, whatever you’re left with, no matter how improbable, must be the truth.”
The researchers suggest that mass extinction actually helped the survivors of the asteroid hit colonise new places and diversify because there was less competition for food from other species.
Dr Jakob Vinther, from the University of Bristol, said: “The asteroid hit would have killed most of the plants, meaning there was no new food.
“However, scavengers like worm lizards that live off dead and decaying matter were able to survive and thrive. Their tunnels would have acted like bomb shelters, allowing them to withstand the asteroid impact and without any competition for food and space, they flourished.”
Their study, published in the Proceedings of the Royal Society B, describes the earliest definitive fossil evidence of worm lizards, around 100-1000 years after the asteroid hit and long after the break-up of Pangaea. The data suggest that the lizards must have travelled across the oceans at least three times: from North America to Europe, from North America to Africa and from Africa to South America.
The summit caldera of Tambora, which is about 6 kilometers wide and 7 kilometers long and more than 1 kilometer deep, was created by the 1815 eruption. Gray eruptive products form the top of the caldera wall (foreground) and appear to be 200-year-old pyroclastic flow or late surge deposits. On the floor of the caldera is an ephemeral lake (center) and a small cone from a post-1815 eruption (lower right of lake). Credit: Katie Preece
The 2010 eruption of the Icelandic volcano Eyjafjallajökull grounded thousands of air flights and spread ash over much of western Europe, yet it was puny compared to the eruption 200 years ago of Tambora, a volcano that probably killed more than 60,000 people in what is now Indonesia and turned summer into winter over much of the Northern Hemisphere.
“Because Tambora ejected sulfurous gas that generated sulfate aerosols in the atmosphere, which block sunlight, the eruption created a ‘year without a summer,’ leading to food shortages — people were eating cats and rats — and very general hardship throughout Europe and eastern North America,” said Stephen Self, an adjunct professor of earth and planetary science at the University of California, Berkeley, and an expert on volcanoes, in particular supervolcano eruptions 10 times larger than Tambora.
Tambora, which blew its top on April 10 and 11, 1815, is an example of the destruction volcanoes can wreak, he said, possibly made worse today by denser populations and our reliance on air transport. Self will deliver an invited talk April 7 at the opening of a four-day conference on Tambora in Bern, Switzerland, and will publish a commentary on the risk posed by volcanic eruptions in the April issue of the journal Nature Geoscience.
“An eruption of that size today would certainly have major effects on air traffic as well as atmospheric circulation around the globe, so we would like to know when the next big one is coming,” Self said. “But we can’t predict that if we don’t know the size of past eruptions and when they took place.”
That information is simply unavailable even for big, Tambora-like eruptions over the past thousand years, he said.
“Even in a country with well-studied volcanoes, like Japan, at least 40 percent of the big eruptions are missing from the record,” he said. “And if you look back beyond the past 1,000 years, to 3,000 or 4,000 years ago, the record gets worse and worse. We know there are big eruptions hiding from the record that we don’t know about.”
Many explosive eruptions send sulfate molecules, primarily sulfuric acid, around the globe that fall as acidic snow on glaciers and ice caps, leaving traces that can be seen in ice cores from Greenland and elsewhere. Self recently suggested that one mysterious ice-core sulfate peak, dating from 1452, resulted from an eruption off the island of Vanuatu in the Pacific Ocean that left behind a submerged hole, or caldera, remembered only through local legend.
“It is high time for a systematic exploration of all the available eruption archives — ice cores, ocean sediments, remotely sensed caldera volumes and geochronological analysis of eruption deposits — so that we have a better chance to understand potential future hazards,” he wrote in Nature Geosciences with coauthor Ralf Gertisser of Keele University in the United Kingdom.
Volcano risk study urged
In January, the Global Volcano Model and the International Association of Volcanology and Chemistry of Earth’s Interior issued a report on the hazards and risks of eruptions around the world. The groups noted a lack of information on the frequency and size of eruptions like Tambora, which makes it hard to estimate the danger to life and property from historically active but not currently erupting volcanoes.
Not surprisingly, the report identified Indonesia as the most dangerous place for volcanoes. Tambora, located on the island of Sumbawa in Indonesia, was the largest and deadliest known eruption of the last 750 years; a possibly larger explosion occurred on the nearby island of Lombok in 1257. Krakatau, on the western end of the Indonesian archipelago, is perhaps the best-known of the Indonesian volcanoes. Its 1883 eruption killed more than 34,000 people and was the second deadliest after Tambora. Tambora erupted three times the amount of ash and lava as Krakatau, Self said.
Recently, scientists have proposed that the eruption of Toba on the island of Sumatra 74,000 years ago was the most destructive super-eruption ever recorded: the explosion created a 100 by 60 kilometer caldera now occupied by Lake Toba, and spread ash as far away as the Himalayas 3,000 kilometers to the northwest.
According to the January report, 90 percent of the volcano risk worldwide is in the five nations of Indonesia, Philippines, Japan, Mexico and Ethiopia.
Self has spent much of his career visiting the calderas of major volcanic eruptions and collecting samples of ash and lava in order to determine when and how much they erupted in the past. In 1979, he was the first modern-day scientist to visit Tambora, a shield volcano somewhat like those in Hawaii, to collect rock for analysis. He later estimated that when it exploded in 1815, it blew out 30 to 50 cubic kilometers of material, a major change from the volcano’s earlier behavior.
Sulfur gas ascended into the stratosphere, spawning sulfate aerosol particles that were carried around the world, blocking sunlight for more than a year. This is the best-known example of volcano-induced global cooling, Self said. Some estimate that the global average temperature dropped more than 1 degree Celsius (1.4 degrees Fahrenheit) as a result, causing crop failures in Asia as well as Europe and North America.
For comparison, Mount St. Helens in Washington erupted about 1 cubic kilometer of material in 1980, while Pinatubo’s output in 1991 was about 5 cubic kilometers.
California’s smoking Long Valley caldera
Mainland North America has its own worrisome volcanoes. Crater Lake was created by an eruption of Tambora’s size 7,700 years ago, while the area around Yellowstone National Park was ground zero for a long series of super-eruptions, the most recent about 640,000 years ago, that blanketed much of the North American continent with ash. Long Valley caldera east of California’s Sierra Nevada, within which sits the town of Mammoth, is considered an active supervolcano, though it’s one and only huge eruption was 760,000 years ago.
Smaller volcanoes, such as Mount Rainier and Mount Hood in Washington and Oregon, respectively, are still considered active, while California’s Mount Lassen erupted just 100 years ago.
“We can’t stop an eruption, but we can prepare to adapt to the immediate impact of ash on air traffic and the delayed effect of sulfate aerosols on crops and vegetation,” Self said. Aside from the immediate, ground-level danger from ash flows, lava and hot gas to people living around an erupting volcano, ash thrown into the air, and sulfate aerosols, can pit airplane windows and damage jet engines, while both can cause respiratory problems downwind.
Self said that the 1816 “year without a summer” was not immediately associated with the Mount Tambora eruption because the western world didn’t learn of its explosion until months later, when reports finally made their way by ship from the Dutch East Indies. Krakatau’s fame comes as much from the existence of a new device, the telegraph, which immediately carried news of the eruption around the world in 1883, as from its size and global impact.
The Tambora eruption may have had one famous outcome. Had it not been for the cold, wet weather it brought to Europe, Mary and Percy Shelley and Lord Byron might not have spent the summer of 1816 telling ghost stories around a log fire in a rented house on Lake Geneva, and Mary Shelley might never have turned the best of those tales into a famous book, Frankenstein.
“Frankenstein was wrought from the year without a summer, all due to this volcano that nobody’s ever heard of,” Self said.
Reference:
Stephen Self, Ralf Gertisser. Tying down eruption risk. Nature Geoscience, 2015; 8 (4): 248 DOI: 10.1038/ngeo2403
Esteban Gazel, a geoscientist at Virginia Tech, collects samples of lava in a variety of locations, in this case Etna, Italy, to probe the chemical evolution of the planet. Credit: Virginia Tech
An international research team, led by a Virginia Tech geoscientist, has revealed information about how continents were generated on Earth more than 2.5 billion years ago — and how those processes have continued within the last 70 million years to profoundly affect the planet’s life and climate.
Published online today in Nature Geoscience, the study details how relatively recent geologic events — volcanic activity 10 million years ago in what is now Panama and Costa Rica — hold the secrets of the extreme continent-building that took place billions of years earlier.
The discovery provides new understanding about the formation of the Earth’s continental crust — masses of buoyant rock rich with silica, a compound that combines silicon and oxygen.
“Without continental crust, the whole planet would be covered with water,” said Esteban Gazel, an assistant professor of geology with Virginia Tech’s College of Science. “Most terrestrial planets in the solar system have basaltic crusts similar to Earth’s oceanic crust, but the continental masses — areas of buoyant, thick silicic crust — are a unique characteristic of Earth.”
The continental mass of the planet formed in the Archaean Eon, about 2.5 billion years ago. The Earth was three times hotter, volcanic activity was considerably higher, and life was probably very limited.
Many scientists think that all of the planet’s continental crust was generated during this time in Earth’s history, and the material continually recycles through collisions of tectonic plates on the outermost shell of the planet.
But the new research shows “juvenile” continental crust has been produced throughout Earth’s history.
“Whether the Earth has been recycling all of its continental crust has always been the big mystery,” Gazel said. “We were able to use the formation of the Central America land bridge as a natural laboratory to understand how continents formed, and we discovered while the massive production of continental crust that took place during the Archaean is no longer the norm, there are exceptions that produce ‘juvenile’ continental crust.”
The researchers used geochemical and geophysical data to reconstruct the evolution what is now Costa Rica and Panama, which was generated when two oceanic plates collided and melted iron- and magnesium-rich oceanic crust over the past 70 million years, Gazel said.
Melting of the oceanic crust originally produced what today are the Galapagos islands, reproducing Achaean-like conditions to provide the “missing ingredient” in the generation of continental crust.
The researchers discovered the geochemical signature of erupted lavas reached continental crust-like composition about 10 million years ago. They tested the material and observed seismic waves traveling through the crust at velocities closer to the ones observed in continental crust worldwide.
Additionally, the researchers provided a global survey of volcanoes from oceanic arcs, where two oceanic plates interact. The western Aleutian Islands and the Iwo-Jima segment of the Izu-Bonin islands of are some other examples of juvenile continental crust that has formed recently, the researchers said.
“This is an interesting paper that makes the case that andesitic melts inferred to derive ultimately by melting of subducted slabs in some modern arcs are a good match for the composition of the average continental crust,” said Roberta L. Rudnick, a Distinguished University Professor and chair of the Department of Geology at the University of Maryland, who was not involved in conducting the research. “The authors focus primarily on Central America, but incorporate global data to strengthen their case that slab melting is important in unusual conditions of modern continent generation — and probably in the past.”
The study raises questions about the global impact newly generated continental crust has had over the ages, and the role it has played in the evolution of not just continents, but life itself.
For example, the formation of the Central American land bridge resulted in the closure of the seaway, which changed how the ocean circulated, separated marine species, and had a powerful impact on the climate on the planet.
“We’ve revealed a major unknown in the evolution of our planet,” said Gazel, who was the senior and corresponding author of the study.
Reference:
Esteban Gazel, Jorden L. Hayes, Kaj Hoernle, Peter Kelemen, Erik Everson, W. Steven Holbrook, Folkmar Hauff, Paul van den Bogaard, Eric A. Vance, Shuyu Chu, Andrew J. Calvert, Michael J. Carr, Gene M. Yogodzinski. Continental crust generated in oceanic arcs. Nature Geoscience, 2015; 8 (4): 321 DOI: 10.1038/ngeo2392
Note: The above story is based on materials provided by Virginia Tech.
This image shows Saurichthys rieppeli, a new species of bony fish from the Middle Triassic of Monte San Giorgio, UNESCO world heritage in Southern Switzerland (length 60 cm). Credit: University of Zurich
Working with an international team, paleontologists at the University of Zurich have discovered two new species of Saurichthys. The ~242 million year old predatory fishes were found in the fossil Lagerstätte Monte San Giorgio, in Ticino. They are distinct from previously known Saurichthys species in the shape of the head and body, suggesting different habitats and diet.
Saurichthys is a predatory fish characterized by a long thin body and a sharply pointed snout with numerous teeth. This distinctive ray-finned fish lived in marine and freshwater environments all over the world 252-201 million years ago during the Triassic period. Two new species of this extinct fish have been discovered by paleontologists at the University of Zurich, working in collaboration with researchers in Germany and China. The first species, “Saurichthys breviabdominalis,” is named for its relatively short body and the second, “Saurichthys rieppeli,” is named after Olivier Rieppel, a Swiss paleontologist formerly based at the University of Zurich. Including the new finds, there are now six species of Saurichthys known from Monte San Giorgio, making it both the most abundant and diverse fish at this classic Middle Triassic locality.
Evidence of different diet and habitat
Both 40 to 60 cm long fishes differ from other species of Saurichthys in skull and body shape. “These differences indicate different hunting styles and habitats in the shallow sea. This enabled multiple species to co-exist,” clarified Heinz Furrer, paleontologist at the University of Zurich and author of this research project. According to Furrer, the ability to occupy multiple specialized feeding and habitat niches may be responsible for the evolutionary success of these fishes, both in the Monte San Giorgio basin and globally.
Monte San Giorgio is world-renowned for its beautifully preserved fossils from the Middle Triassic time (~239-243 million years ago). Large-scale excavations conducted by the University of Zürich between 1924 and 2004 yielded a substantial number of fossil reptiles and fishes. As part of a research project funded by the Swiss National Science Foundation, scientists at the Paleontological Institute and Museum, University of Zurich have prepared and studied over a hundred well-preserved specimens over the last three years.
Reference:
Erin E. Maxwell, Carlo Romano, Feixiang Wu, Heinz Furrer. Two new species ofSaurichthys(Actinopterygii: Saurichthyidae) from the Middle Triassic of Monte San Giorgio, Switzerland, with implications for character evolution in the genus. Zoological Journal of the Linnean Society, 2015; 173 (4): 887 DOI: 10.1111/zoj.12224
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This image shows a house damaged by Sept. 2013 debris flow in Big Thompson Canyon, Colorado Front Range; deposit covers part of US Hwy 34. Credit: Photo by Jonathan Godt, 20 Sept. 2013; published on the cover of the Oct. 2014 issue of GSA Today.
Scott W. Anderson and colleagues use repeat aerial LiDAR to quantify the erosional impact of the heavy rains that inundated the Colorado Front Range in September 2013. The five-day storm triggered more than 1,100 landslides and debris flows in a 3,430-square-kilometer area due to 200-450 mm of heavy, steady rainfall. This number of hillslope failures in a single event represents unprecedented activity for the region in its ~150 years of written history.
This study for Geology addresses the role of such large, rare events in shaping landscapes by documenting the location and size of landslides and debris flows. Anderson and colleagues use before-and-after high-resolution topographic data from airborne laser mapping (LiDAR) to quantify landslide erosion.
The “before” LiDAR mapping of Boulder Creek was completed in 2010. With a few weeks of the storm, the authors repeated the aerial survey. They then subtracted the 2013 topographic data from the 2010 topographic data where the datasets overlapped — west of Boulder, Colorado — to produce a digital elevation model (DEM) of difference.
They located 120 landslides and debris flows ranging in size from 10 to 21,000 cubic meters, all on slopes greater than 20 degrees. On average, about 15 mm of lowering occurred in basins in which landslides occurred.
Other methods have shown that it takes hundreds to thousands of years to loosen this much sediment from rock. These results therefore show that it is these rare debris flows that transport the sediment off the steep hillslopes along the eastern edge of the Front Range.
This study both highlights the importance of rare events in long-term erosion of this landscape and helps to explain why modern sediment yields may greatly underestimate long-term denudation rates in such settings. Debris flows dominate sediment export from storage on the steep hillslopes that bound the canyons draining the Colorado Front Range. Landscapes evolve over time scales that greatly exceed the period of historical records. It is therefore important to understand the degree to which modern observations capture the full range of geologically formative processes and process rates.
Refernce:
Scott W. Anderson et al., Dept. of Geography and Institute of Arctic and Alpine Research (INSTAAR), University of Colorado, Boulder, Colorado, USA; currently at U.S. Geological Survey, Tacoma, Washington 98402, USA. Published online ahead of print on 27 Mar. 2015; DOI: 10.1130/G36507.1
DRI and NASA JPL engineers prepare coring device to sample thermokarst lake sediments in early November on the North Slope of Alaska. Credit: Alison Murray, DRI
New research into the changing ecology of thousands of shallow lakes on the North Slope of Alaska suggests that in scenarios of increasing global temperatures, methane-generating microbes, found in thawing lake sediments, may ramp up production of the potent greenhouse gas – which has a global warming potential 25 times greater than carbon dioxide.
A study published this month in Geobiology – resulting from five-years of collaborative research led by Nevada’s Desert Research Institute (DRI) and including scientists from NASA’s Jet Propulsion Laboratory (JPL), Montana State University, and University of California, Riverside – illustrates how the decomposition of organic matter in thermokast lake sediments can produce up to three times more biological methane gas emissions when subjected to increased temperatures in a simulated environment.
Further, researchers found that the methane detected in in lake sediments in this region can arise from both ancient theremogenic sources deep in the earth, or from shallow contemporary biological sources. Interestingly, the coastal plain in the North Slope of Alaska is estimated to contain 53-billion cubic feet of natural gas trapped under the permafrost ice cap.
Thermokarst lakes occur as permafrost thaws and creates surface depressions where meltwater accumulates , converting what was previously frozen land into small freshwater lakes with active decomposing sediment layers.
While scientists have long understood that methane and carbon dioxide releases from thawing permafrost are important sources of global greenhouse gas emissions, little is known about the sources and rates of methane production (known as methanogensis) from microbial communities found in these changing environments.
“The large amount of organic matter stored in the thaw layer between the water column and the permafrost table serves as a significant source of carbon for methanogensis,” explained Paula Matheus Carnevali, a doctoral student at DRI and the study’s lead author. “Identifying and understanding the production sources of methane will improve our ability to generate accurate predictions about the changing climate in the Arctic.”
The study focused on methane dynamics within 16 sediment cores collected over a period of four years from two Alaskan thermokarst lakes, near Barrow, Alaska. Samples were obtained from three sites, one proximal to an active, submerged natural gas seep and another from a site approximately one-kilometer away from the seep site. The second lake was located about 13-km to the northwest, and did not have visibly active seeps.
Simulated climate scenarios were performed in a controlled DRI laboratory in Reno, Nevada and scientists analyzed the potential for increased biological production of methane from methanogens found in the lake sediments; the role of the sediment geochemistry in this process; and the temperature dependency of this process.
“This study marks an important step in recognizing that there are different methane sources in close proximity that may respond differently in the changing Alaskan arctic ecosystems,” said Alison Murray, Ph.D., a principal investigator on the study and expert in microbial ecology and archaea found in some of Earth’s most extreme environments.
“In scenarios of warming climate,” Murray said, “our measurements indicate that biological methane production may play a larger role in total methane emissions in the future, which could have a significant impact on our climate.”
Reference:
Methane sources in arctic thermokarst lake sediments on the North Slope of Alaska. DOI: 10.1111/gbi.12124
Fumaroles escape from Fourpeaked volcano through a fissure in Fourpeaked Glacier on 24 September 2006 Credit: Read, Cyrus, USGS
Particles emitted during major volcanic eruptions cool the atmosphere due to a ‘parasol’ effect that reflects sunlight. The direct impact of these particles in the atmosphere is fairly short, lasting two to three years. However, they alter for more than 20 years the North Atlantic Ocean circulation, which connects surface and deep currents and influences the climate in Europe. This is the conclusion of a study by researchers from the CNRS, IRD, CEA and Météo‐France* who combined, for the first time, climate simulations, recent oceanographic data, and information from natural climate records. Their findings** are published in Nature Communications on March 30th.
The Atlantic Ocean is home to variations in surface temperatures that last for several decades, affecting Europe’s climate. This slow variability is caused by changes in the ocean circulation, which connects surface to deep currents and transports heat from the tropics to the Norway and Greenland seas. However, the reason for this variability is still poorly understood.
In order to elucidate its mechanisms, the researchers first used information from the natural climate record covering the last millennium. By studying the chemical composition of water from ice cores in Greenland, they were able to estimate past temperature changes. The data highlights the close connection between the surface temperature of the Atlantic Ocean and air temperatures over Greenland, showing that climate variability in the region is a periodic phenomenon some of whose cycles, or oscillations, last around twenty years.
By using numerical simulations from more than twenty different climate models, the researchers also showed that major volcanic eruptions, like that of Mount Agung, Indonesia, in 1963, or Pinatubo in the Philippines in 1991, could significantly alter ocean circulation in the North Atlantic. This is because the large quantities of particles emitted by these eruptions into the upper atmosphere reflect part of the solar radiation, rather like a parasol, causing the climate at Earth’s surface to cool. The cooling, which only lasts two or three years, then triggers a rearrangement of ocean circulation in the North Atlantic Ocean. Around fifteen years after the beginning of the eruption, the circulation speeds up. It then slows down after twenty-five years, before accelerating again thirty-five years after the phenomenon. Volcanic eruptions thus appear to act on the ocean circulation in the North Atlantic rather like a pacemaker, causing variability over a twenty-year period.
The scientists confirmed these results by comparing them with observations of ocean salinity, a key factor for the sinking of water and therefore for ocean circulation. In numerical simulations and modern oceanographic data they detected similar variations in the early 1970s and 1990s connected to the eruption of the Agung volcano. Using data from Greenland ice cores and observations carried out on bivalve molluscs collected to the north of Iceland and dating back more than 500 years, as well as a simulation of the climate over the last thousand years, the researchers systematically identified acceleration of ocean circulation fifteen years after five volcanic eruptions that took place several hundred years ago.
Lastly, the researchers revealed the interference produced by the latest three main eruptions, Agung in 1963, El Chichón in Mexico in 1982, and Pinatubo in 1991, explaining for the first time the recent variability of currents in the North Atlantic ocean. They conclude that a major eruption in the near future could have an impact on the currents in the North Atlantic Ocean — and hence on our ability to predict the variability of the climate in Europe — over several decades. They now hope to consolidate these findings by collecting data from additional sources, especially in paleoclimatology.
* From the Laboratoire Environnements et Paléo-environnements Océaniques et Continentaux (CNRS/Université de Bordeaux), Centre National de Recherches Météorologiques — Groupe d’Etude de l’Atmosphère Météorologique (CNRS/Météo France), and Laboratoire d’Océanographie et du Climat: Expérimentations et Approches Numériques (CNRS/UPMC/MNHN/IRD) and Laboratoire des Sciences du Climat et de l’Environnement (CNRS/CEA/UVSQ), both part of the Institut Pierre Simon Laplace.
**The project was funded by the Agence Nationale de la Recherche via the ‘Groenland Vert’ project in the ‘Changements Environnementaux Planétaires et Société’ program (2011-2015).
Reference:
Didier Swingedouw, Pablo Ortega, Juliette Mignot, Eric Guilyardi, Valérie Masson-Delmotte, Paul G. Butler, Myriam Khodri, Roland Séférian. Bidecadal North Atlantic ocean circulation variability controlled by timing of volcanic eruptions. Nature Communications, 2015; 6: 6545 DOI: 10.1038/ncomms7545
Note: The above story is based on materials provided by CNRS.
Microscopic gold-rich and lead-rich particles in a municipal biosolids sample. Credit: Heather Lowers, USGS Denver Microbeam Laboratory
Poop could be a goldmine — literally. Surprisingly, treated solid waste contains gold, silver and other metals, as well as rare elements such as palladium and vanadium that are used in electronics and alloys. Now researchers are looking at identifying the metals that are getting flushed and how they can be recovered. This could decrease the need for mining and reduce the unwanted release of metals into the environment.
“If you can get rid of some of the nuisance metals that currently limit how much of these biosolids we can use on fields and forests, and at the same time recover valuable metals and other elements, that’s a win-win,” says Kathleen Smith, Ph.D.
“There are metals everywhere,” Smith says, noting they are “in your hair care products, detergents, even nanoparticles that are put in socks to prevent bad odors.” Whatever their origin, the wastes containing these metals all end up being funneled through wastewater treatment plants, where she says many metals end up in the leftover solid waste.
At treatment plants, wastewater goes through a series of physical, biological and chemical processes. The end products are treated water and biosolids. Smith, who is at the U.S. Geological Survey (USGS), says more than 7 million tons of biosolids come out of U.S. wastewater facilities each year. About half of that is used as fertilizer on fields and in forests, while the other half is incinerated or sent to landfills.
Smith and her team are on a mission to find out exactly what is in our waste. “We have a two-pronged approach,” she says. “In one part of the study, we are looking at removing some regulated metals from the biosolids that limit their use for land application.
“In the other part of the project, we’re interested in collecting valuable metals that could be sold, including some of the more technologically important metals, such as vanadium and copper that are in cell phones, computers and alloys,” Smith said. To do this, they are taking a page from the industrial mining operations’ method book and are experimenting with some of the same chemicals, called leachates, which this industry uses to pull metals out of rock. While some of these leachates have a bad reputation for damaging ecosystems when they leak or spill into the environment, Smith says that in a controlled setting, they could safely be used to recover metals in treated solid waste.
So far, her group has collected samples from small towns in the Rocky Mountains, rural communities and big cities. For a more comprehensive picture, they plan to combine their information with many years’ worth of existing data collected by the Environmental Protection Agency and other groups at the USGS.
In the treated waste, Smith’s group has already started to discover metals like platinum, silver and gold. She states that they have observed microscopic-sized metal particles in biosolids using a scanning electron microscope. “The gold we found was at the level of a minimal mineral deposit,” she says, meaning that if that amount were in rock, it might be commercially viable to mine it. Smith adds that “the economic and technical feasibility of metal recovery from biosolids needs to be evaluated on a case-by-case basis.”
In a recent Environmental Science & Technology paper another research group also studying this issue calculated that the waste from 1 million Americans could contain as much as $13 million worth of metals. That’s money that could help fuel local economies.
The researchers acknowledge funding from the U.S. Geological Survey Mineral Resources Program.
Reference:
Paul Westerhoff, Sungyun Lee, Yu Yang, Gwyneth W. Gordon, Kiril Hristovski, Rolf U. Halden, Pierre Herckes. Characterization, Recovery Opportunities, and Valuation of Metals in Municipal Sludges from U.S. Wastewater Treatment Plants Nationwide. Environmental Science & Technology, 2015; 150127115347007 DOI: 10.1021/es505329q
The new fossil is the only record of an adult female insect from the Mesozoic, an era that spanned roughly 180 million years. Credit: CCBY 4.0 Wang et al.
Scientists have uncovered the earliest fossilised evidence of an insect caring for its young.
The findings, published in the journal eLife, push back the earliest direct evidence of insect brood care by more than 50 million years, to at least 100 million years ago when dinosaurs dominated the earth.
The new fossil is the only record of an adult female insect from the Mesozoic, an era that spanned roughly 180 million years. The Mesozoic era was the age of the reptiles and saw both the rise and fall of the dinosaurs, as well as the breakup of the supercontinent Pangaea.
The female ensign scale insect is preserved in a piece of amber retrieved from a mine in northern Myanmar (Burma). The specimen was trapped while carrying around 60 eggs and her first freshly hatched nymphs. The eggs and nymphs are encased in a wax-coated egg sac on the abdomen. This primitive form of brood care protects young nymphs from wet and dry conditions and from natural enemies until they have acquired their own thin covering of wax.
The behaviour has been so successful for promoting the survival of offspring that it is still common in insects today. Young nymphs hatch inside the egg sac and remain there for a few days before emerging into the outside world.
The findings may even offer an explanation for the early diversification of scale insects. The emergence of flowering plants and ants are thought to have been crucial for the rapid evolution of many new insect species, but they were not yet present during the evolutionary history of the ensign scale insects.
“Brood care could have been an important driver for the early radiation of scale insects, which occurred during the end of the Jurassic or earliest Cretaceous period during the Mesozoic era,” says lead author Bo Wang, an associate professor at the Chinese Academy of Sciences.
Fossilised evidence of animals caring for their young is extremely rare, especially in insects. Wingless females were largely immobile, so were less likely to be accidentally buried. A cockroach from a similar period was reported carrying a mass of eggs, but cockroaches often deposit their eggs rather than brooding them. The only other direct evidence of brood care is from Cenozoic ambers, the era that extends to the present and began about 65 million years ago with the extinction of the dinosaurs.
“Although analysis seemed to suggest that ancient insects evolved brood care, this is the first direct, unequivocal evidence for the fossil record,” says Wang.
The team have named this new species Wathondara kotejai after the goddess of earth in Buddhist mythology and the late Polish entomologist Jan Koteja.
Reference:
The paper ‘Brood care in a 100-million-year-old scale insect’ can be freely accessed online at DOI: 10.7554/eLife.05447
Note : The above story is based on materials provided by eLife.
At the UC Davis Bodega Marine Laboratory, Sarah Moffitt examines fossils within a marine sediment core. Credit: Copyright Joe Proudman, UC Davis
A 30-foot-long core sample of Pacific Ocean seafloor is changing what we know about ocean resiliency in the face of rapidly changing climate. A new study reports that marine ecosystems can take thousands, rather than hundreds, of years to recover from climate-related upheavals. The study’s authors–including Peter Roopnarine, PhD, of the California Academy of Sciences–analyzed thousands of invertebrate fossils to show that ecosystem recovery from climate change and seawater deoxygenation might take place on a millennial scale. The revolutionary study is the first of its kind, and is published today in the Early Edition of the journal PNAS.
The scientific collaborative–led by Sarah Moffitt, PhD, from the UC Davis Bodega Marine Laboratory and Coastal and Marine Sciences Institute–analyzed more than 5,400 invertebrate fossils, from sea urchins to clams, within a sediment core from offshore Santa Barbara, California.
“In this study, we used the past to forecast the future,” says Roopnarine, Academy curator of invertebrate zoology and geology. “Tracing changes in marine biodiversity during historical episodes of warming and cooling tells us what might happen in years to come. We don’t want to hear that ecosystems need thousands of years to recover from disruption, but it’s critical that we understand the global need to combat modern climate impacts.”
The tube-like sediment core is a slice of ocean life as it existed between 3,400 and 16,100 years ago, and provides a before-and-after snapshot of what happened during the last major deglaciation–a time of abrupt climate warming, melting polar ice caps, and expansion of low oxygen zones in the ocean. The new study documents how long it has historically taken for ecosystems to begin recovery following dramatic shifts in climate.
Previous marine sediment studies reconstructing Earth’s climatic history rely heavily upon simple, single-celled organisms called Foraminifera. This week’s study explores multicellular life–in the form of invertebrates–in pursuit of a more complete picture of ocean ecosystem resilience during past periods of climate change.
“The complexity and diversity of a community depends on how much energy is available,” says Roopnarine. “To truly understand the health of an ecosystem and the food webs within, we have to look at the simple and small as well as the complex. In this case, marine invertebrates give us a better understanding of the health of ecosystems as a whole.”
The study’s all-important sediment core revealed an ancient history of abundant, diverse, and well-oxygenated seafloor ecosystems, followed by a period of oxygen loss and warming that seems to have triggered a rapid loss of biodiversity. The study reports that invertebrate fossils are nearly non-existent during times of lower-than-average oxygen levels.
Moffitt emphasized the importance of using a large, 30-foot core sample from one portion of the seafloor, saying the team “cut it up like a cake” to analyze the full, unbroken record.
In periods of fewer than 100 years, oceanic oxygen levels decreased between 0.5 and 1.5 mL/L. Sediment samples during these periods show that relatively minor oxygen fluctuations can result in dramatic changes for seafloor communities.
‘New normal’ of rapid climate change
The study results suggest that future periods of global climate change may result in similar ecosystem-level effects with millennial-scale recovery periods. As the planet warms, scientists expect to see much larger areas of low-oxygen “dead zones” in the world’s oceans.
“Folks in Oregon and along the Gulf of Mexico are all-too-familiar with the devastating impacts of low-oxygen ocean conditions on local ecosystems and economies,” says Roopnarine. “We must explore how ocean floor communities respond to upheaval as we adapt to a ‘new normal’ of rapid climate change. We humans have to think carefully about the planet we are leaving for future generations.”
Reference:
Sarah E. Moffitt, Tessa M. Hill, Peter D. Roopnarine, and James P. Kennett. Response of seafloor ecosystems to abrupt global climate change. PNAS, 2015 DOI: 10.1073/pnas.1417130112
Looking toward Svalbard, an archipelago off the coast of Norway, from the Isfjorden fjord. Credit: Joel Johnson
Research led by a University of New Hampshire professor has identified a new source of methane for gas hydrates — ice-like substances found in sediment that trap methane within the crystal structure of frozen water — in the Arctic Ocean. The findings, published online now in the May 2015 journal Geology, point to a previously undiscovered, stable reservoir for abiotic methane — methane not generated by decomposing carbon — that is “locked” away from the atmosphere, where it could impact global climate change.
“We’ve found an example where methane produced at a mid-ocean ridge is locked up in stable, deep water gas hydrate, preventing it from possibly getting out of the seafloor,” says lead author Joel Johnson, associate professor of geology at UNH and guest researcher at the Center for Arctic Gas Hydrate, Environment and Climate (CAGE) at UiT The Arctic University of Norway in Tromsø. Johnson notes that the findings, which pinpointed a source of abiotic methane ¬produced in seafloor crust, indicate gas hydrates throughout the Arctic may be supplied by a significant portion of abiotic gas.
The study, “Abiotic methane from ultraslow-spreading ridges can charge Arctic gas hydrates,” focused on the Arctic mid-ocean ridge system, one of two so-called ultraslow-spreading ridge regions on Earth. Scientists have known that abiotic methane can be generated in these ridges through a process called serpentization, which involves the reaction of seawater with hot mantle-derived rocks exposed during slow to ultraslow mid-ocean ridge spreading.
While on sabbatical last year (2013-14) at CAGE, Johnson and his co-authors from that institution embarked on two cruises in the unique geologic and oceanographic region called the Fram Strait, a deep, narrow gateway to the Arctic Ocean between Greenland and the Norwegian archipelago of Svalbard. There, fast-moving currents move sediment, uncommon on most mid-ocean ridges, into sediment drifts that cover the ridges. Using a seismic data acquisition system, they found a methane hydrate system within those sediments.
The discovery surprised the researchers. “We didn’t know whether or not abiotic methane could supply gas hydrate systems so close to mid-ocean ridges” Johnson says. “It had been thought that mid-ocean ridge environments might be too hot for gas hydrates to be stable.”
Indeed, those methane hydrates are remarkably stable: The researchers showed that the hydrate system is long-lived, about two million years old. Further, because the hydrates exist under very deep water — more than 1500 meters — the methane is less vulnerable to potential release due to changing sea levels or ocean warming. Such stability has important implications for climate change; as a greenhouse gas, methane is 20 times more potent than carbon dioxide.
“This work shows there are parts of the Arctic where abiotic methane is coming up to the seafloor and instead of coming out, it is trapped in gas hydrates; it’s finding itself in a stable environment for millions of years,” says Johnson. Where climate change is concerned, he adds, “this is not the part of the gas hydrate system that is most susceptible to change in a warming Arctic Ocean.”
Although his focus is on the crust of Earth, not interplanetary space, Johnson notes that these findings are interesting, as some researchers have suggested abiotic methane formed by serpentinization may exist and reside as gas hydrates on Mars. And as gas hydrates gain popularity as potential fuel for the future here on Earth, the energy sector is likely to take notice as well. “This is a new source of methane for gas hydrates in the Arctic that could be quite extensive,” Johnson says.
Reference:
J. E. Johnson, J. Mienert, A. Plaza-Faverola, S. Vadakkepuliyambatta, J. Knies, S. Bunz, K. Andreassen, B. Ferre. Abiotic methane from ultraslow-spreading ridges can charge Arctic gas hydrates. Geology, 2015; DOI: 10.1130/G36440.1
This image shows a freshly excavated fossil specimen of Yawunik kootenayi. Credit: Robert Gaines
What do butterflies, spiders and lobsters have in common? They are all surviving relatives of a newly identified species called Yawunik kootenayi, a marine creature with two pairs of eyes and prominent grasping appendages that lived as much as 508 million years ago – more than 250 million years before the first dinosaur.
The fossil was identified by an international team led by palaeontologists at the University of Toronto (U of T) and the Royal Ontario Museum (ROM) in Toronto, as well as Pomona College in California. It is the first new species to be described from the Marble Canyon site, part of the renowned Canadian Burgess Shale fossil deposit.
Yawunik had evolved long frontal appendages that resemble the antennae of modern beetles or shrimps, though these appendages were composed of three long claws, two of which bore opposing rows of teeth that helped the animal catch its prey.
“This creature is expanding our perspective on the anatomy and predatory habits of the first arthropods, the group to which spiders and lobsters belong,” said Cedric Aria, a PhD candidate in U of T’s Department of Ecology & Evolutionary Biology and lead author of the resulting study published this week in Palaeontology. “It has the signature features of an arthropod with its external skeleton, segmented body and jointed appendages, but lacks certain advanced traits present in groups that survived until the present day. We say that it belongs to the ‘stem’ of arthropods.”
The study presents evidence that Yawunik was capable of moving its frontal appendages backward and forward, spreading them out during an attack and then retracting them under its body when swimming. Coupled with the long, sensing whip-like flagella extending from the tip of the claws, this makes the frontal appendages of the animal some of the most versatile and complex in all known arthropods.
“Unlike insects or crustaceans, Yawunik did not possess additional appendages in the head that were specifically modified to process food,” said Aria. “Evolution resulted here in a combination of adaptations onto the frontal-most appendage of this creature, maybe because such modifications were easier to acquire.
“We know that the larvae of certain crustaceans can use their antennae to both swim and gather food. But a large active predator such as a mantis shrimp has its sensory and grasping functions split up between appendages. Yawunik and its relatives tell us about the condition existing before such a division of tasks among parts of the organism took place.”
The Marble Canyon site is located in British Columbia’s Kootenay National Park, 40 kilometres south from the original Burgess Shale in Yoho National Park. Aria was part of the team that discovered the site in 2012, led by Jean-Bernard Caron, an associate professor at U of T’s Departments of Earth Sciences and Ecology & Evolutionary Biology and curator of invertebrate palaeontology at the ROM, and Robert Gaines, associate professor at the Department of Geology at Pomona College in California, both co-authors of the study.
“Yawunik is the most abundant of the large new species of the Marble Canyon site, and so, as a predator, it held a key position in the food network and had an important impact on this past ecosystem,” said Caron. “This animal is therefore important for the study of Marble Canyon, and shows how the site increases the significance of the Burgess Shale in understanding the dawn of animals.”
The study benefited from cutting-edge techniques of fossil imagery, including so-called “elemental mapping,” which consists in detecting the atomic composition of the fossil and the sediment surrounding it.
“Our understanding of these organisms rests upon interpreting their fossil remains,” said Gaines. “These fossils are a composed of a mosaic of delicate original organic material and minerals that replicate parts of fossil anatomy.
“The scanning electron microscope allows us to make maps of the fossils that reveal their composition. This gives us a remarkable perspective on the fossils, allowing anatomical structures to be visualized more precisely. This technique also provides insight into the unusual fossilization process that was at work here.”
The new creature is named in tribute to the Ktunaxa People who have long inhabited the Kootenay area where the Marble Canyon locality was found. It owes its name to “Yawu?nik?”, a mythological figure described as a huge and fierce marine creature, killing and causing such mayhem that it triggered an epic hunt by other animals to bring the threat down.
“We wanted to acknowledge the Ktunaxa culture, and given the profile of Yawunik, it looked like a natural choice of name,” Aria said.
“Yawu?nik? is a central figure in the Ktunaxa creation story, and, as such, is a vital part of Ktunaxa oral history,” said Donald Sam, Ktunaxa Nation Council Director of Traditional Knowledge and Language. “I am ecstatic that the research team recognizes how important our history is in our territory, and chose to honour the Ktunaxa through this amazing discovery.”
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Reference:
Cédric Aria, Jean-Bernard Caron and Robert Gaines. A large new leanchoiliid from the Burgess Shale and the influence of inapplicable states on stem arthropod phylogeny. Palaeontology, 27 MAR 2015 DOI: 10.1111/pala.12161
Figure 1 is from Pondrelli et al. (A) Location map of the study area on MOLA-based shaded relief map. Topographic contours (in black, 1000 m spacing) are indicated. (B) High Resolution Stereo Camera (HRSC) mosaic of the mapped area. Topographic contours (in white, 500 m spacing) are indicated. (C) Excerpt of the geological map by Scott and Tanaka (1986) on an HRSC mosaic. Geologic units (see text for more details): Npl1–Noachian cratered unit of the plateau sequence; Npl2–Noachian subdued crater unit of the plateau sequence; Hr–Hesperian ridged plains material. (D) Footprints of High Resolution Imaging Science Experiment (HiRISE) coverage on an HRSC mosaic. The white fi lling indicates stereo pairs. The area is fully covered by Context Camera (CTX) imagery. Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) scenes used in this study are recognizable by the hourglass shape. Click on the figure for a larger image. Credit: Pondrelli et al. and GSA Bulletin
Monica Pondrelli and colleagues investigated the Equatorial Layered Deposits (ELDs) of Arabia Terra in Firsoff crater area, Mars, to understand their formation and potential habitability. On the plateau, ELDs consist of rare mounds, flat-lying deposits, and cross-bedded dune fields. Pondrelli and colleagues interpret the mounds as smaller spring deposits, the flat-lying deposits as playa, and the cross-bedded dune fields as aeolian. They write that groundwater fluctuations appear to be the major factor controlling ELD deposition.
Pondrelli and colleagues also note that the ELDs inside the craters would likely have originated by fluid upwelling through the fissure ridges and the mounds, and that lead to evaporite precipitation. The presence of spring and playa deposits points to the possible presence of a hydrological cycle, driving groundwater upwelling on Mars at surface temperatures above freezing. Pondrelli and colleagues write that such conditions in a similar Earth environment would have been conducive for microbial colonization.
As a basis for their research, Pondrelli and colleagues produced a detailed geological map of the Firsoff crater area. The new map includes crater count dating, a survey of the stratigraphic relations, and analysis of the depositional geometries and compositional constraints. They note that this ELD unit consists of sulfates and shows other characteristics typical of evaporites such as polygonal pattern and indications of dissolution.
Reference:
Equatorial layered deposits in Arabia Terra, Mars: Facies and process variability
M. Pondrelli et al., International Research School of Planetary Sciences, Università d’Annunzio, Pescara, Italy. Published online ahead of print on 10 Mar. 2015; DOI: 10.1130/B31225.1.
Modern technology relies on virtually all of the stable elements of the periodic table. This figure, which pictures the concentrations (in parts per million) of elements on a printed circuit board, provides an illustration of that fact. The concentrations of copper and iron are obviously the highest, and others such as cesium are much lower, but concentration clearly does not reflect elemental importance: all the elements are required in order to maintain the functions for which the board was designed. Credit: Thomas Graedel, et al
In a new paper, a team of Yale researchers assesses the “criticality” of all 62 metals on the Periodic Table of Elements, providing key insights into which materials might become more difficult to find in the coming decades, which ones will exact the highest environmental costs — and which ones simply cannot be replaced as components of vital technologies.
During the past decade, sporadic shortages of metals needed to create a wide range of high-tech products have inspired attempts to quantify the criticality of these materials, defined by the relative importance of the elements’ uses and their global availability.
Many of the metals traditionally used in manufacturing, such as zinc, copper, and aluminum, show no signs of vulnerability. But other metals critical in the production of newer technologies — like smartphones, infrared optics, and medical imaging — may be harder to obtain in coming decades, said Thomas Graedel, the Clifton R. Musser Professor of Industrial Ecology at the Yale School of Forestry & Environmental Studies and lead author of the paper.
The study — which was based on previous research, industry information, and expert interviews — represents the first peer-reviewed assessment of the criticality of all of the planet’s metals and metalloids.
“The metals we’ve been using for a long time probably won’t present much of a challenge. We’ve been using them for a long time because they’re pretty abundant and they are generally widespread geographically,” Graedel said. “But some metals that have become deployed for technology only in the last 10 or 20 years are available almost entirely as byproducts. You can’t mine specifically for them; they often exist in small quantities and are used for specialty purposes. And they don’t have any decent substitutes.”
These findings illustrate the urgency for new product designs that make it easier to reclaim materials for re-use, Graedel said.
The paper, published in the Proceedings of the National Academy of Sciences, encapsulates the Yale group’s five-year assessment of the criticality of the planet’s metal resources in the face of rising global demand and the increasing complexity of modern products.
According to the researchers, criticality depends not only on geological abundance. Other important factors include the potential for finding effective alternatives in production processes, the degree to which ore deposits are geopolitically concentrated, the state of mining technology, regulatory oversight, geopolitical initiatives, regional instabilities, and economic policies.
In order to assess the state of all metals, researchers developed a methodology that characterizes criticality in three areas: supply risk, environmental implications, and vulnerability to human-imposed supply restrictions.
They found that supply limits for many metals critical in the emerging electronics sector (including gallium and selenium) are the result of supply risks. The environmental implications of mining and processing present the greatest challenges with platinum-group metals, gold, and mercury. For steel alloying elements (including chromium and niobium) and elements used in high-temperature alloys (tungsten and molybdenum), the greatest vulnerabilities are associated with supply restrictions.
Among the factors contributing to extreme criticality challenges are high geopolitical concentration of primary production (for example, 90 to 95% of the global supply of rare Earth metals comes from China); lack of available substitutes (there is no adequate substitute for indium, which is used in computer and cell phone displays); and political instability (a significant fraction of tantalum, used widely in electronics, comes from the war-ravaged Democratic Republic of the Congo).
The researchers also analyzed how recycling rates have evolved over the years and the degree to which different industries are able to utilize “non-virgin” sources of materials. Some materials, such as lead, are highly recycled because they are typically used in bulk, Graedel said. But the relatively rare materials that have become critical in some modern electronics are far more difficult to recycle because they are used in such miniscule amounts — and can be difficult to extricate from the increasingly complex and compact new technologies.
“I think these results should send a message to product designers to spend more time thinking about what happens after their products are no longer being used,” he said. “So much of what makes the recycling of these materials difficult is their design. It seems as if it’s time to think a little bit more about the end of these beautiful products.”
Reference:
T. E. Graedel, E. M. Harper, N. T. Nassar, Philip Nuss, Barbara K. Reck. Criticality of metals and metalloids. Proceedings of the National Academy of Sciences, 2015; 201500415 DOI: 10.1073/pnas.1500415112
This is a cast of the ‘Nariokotome Boy’ (Homo ergaster) skeleton. Credit: Jay Stock
New research harnessing fragmentary fossils suggests our genus has come in different shapes and sizes since its origins over two million years ago, and adds weight to the idea that humans began to colonise Eurasia while still small and lightweight.
One of the dominant theories of our evolution is that our genus, Homo, evolved from small-bodied early humans to become the taller, heavier and longer legged Homo erectus that was able to migrate beyond Africa and colonise Eurasia. While we know that small-bodied Homo erectus — averaging less than five foot (152cm) and under 50kg — were living in Georgia in southern Europe by 1.77 million years ago, the timing and geographic origin of the larger body size that we associate with modern humans has, until now, remained unresolved.
But a joint study by researchers at the Universities of Cambridge and Tübingen (Germany), published today in the Journal of Human Evolution, has now shown that the main increase in body size occurred tens of thousands of years after Homo erectus left Africa, and primarily in the Koobi Fora region of Kenya. According to Manuel Will, a co-author of the study from the Department of Early Prehistory and Quaternary Ecology at Tübingen, “the evolution of larger bodies and longer legs can thus no longer be assumed to be the main driving factor behind the earliest excursions of our genus to Eurasia.”
Researchers say the results from a new research method, using tiny fragments of fossil to estimate our earliest ancestors’ height and body mass, also point to the huge diversity in body size we see in humans today emerging much earlier than previously thought.
“What we’re seeing is perhaps the beginning of a unique characteristic of our own species — the origins of diversity,” said Dr Jay Stock, co-author of the study from the University of Cambridge’s Department of Archaeology and Anthropology. “It’s possible to interpret our findings as showing that there were either multiple species of early human, such as Homo habilis, Homo ergaster and Homo rudolfensis, or one highly diverse species. This fits well with recent cranial evidence for tremendous diversity among early members of the genus Homo.”
“If someone asked you ‘are modern humans 6 foot tall and 70kg?’ you’d say ‘well some are, but many people aren’t,’ and what we’re starting to show is that this diversification happened really early in human evolution,” said Stock.
The study is the first in 20 years to compare the body size of the humans who shared earth with mammoths and sabre-toothed cats between 2.5 and 1.5 million years ago. It is also the first time that many fragmentary fossils — some as small as toes and tiny ankle bones no more than 5cm long — have been used to make body size estimates.
Comparing measurements of fossils from sites in Kenya, Tanzania, South Africa, and Georgia, the researchers found that there was significant regional variation in the size of early humans during the Pleistocene. Some groups, such as those who lived in South African caves, averaged 4.8 feet tall; some of those found in Kenya’s Koobi Fora region would have stood at almost 6 foot, comparable to the average of today´s male population in Britain.
“Basically every textbook on human evolution gives the perspective that one lineage of humans evolved larger bodies before spreading beyond Africa. But the evidence for this story about our origins and the dispersal out of Africa just no longer really fits,” said Stock. “The first clues came from the site of Dmanisi in Georgia where fossils of really small-bodied people date to 1.77 million years ago. This has been known for several years, but we now know that consistently larger body size evolved in Eastern Africa after 1.7 million years ago, in the Koobi Fora region of Kenya.”
“We tend to simplify our interpretations because the fossil record is patchy and we have to explain it in some way. But revealing the diversity that exists is just as important as those broad, sweeping explanations.”
Previous studies have been based on small samples of only 10-15 fossils because techniques for calculating the height and body mass of individuals required specific pieces of bone such as the hip joint or most of a leg bone. Stock and Will have used a sample size three times larger, estimating body size for over 40 specimens contained in collections all over Africa and Georgia, making it the largest comparative study conducted so far.
Instead of waiting for new fossils to be discovered and hoping that they contained these specific bones, Stock and Will decided to try a different approach and make use of previously over-looked fossils. In what Stock describes as a “very challenging project,” they spent a year developing new equations that allowed them to calculate the height and body mass of individuals using much smaller bones, some as small as toes. By comparing these bones to measurements taken from over 800 modern hunter-gatherer skeletons from around the world and applying various regression equations, the researchers were able to estimate body size for many new fossils that have never been studied in this way before.
“In human evolution we see body size as one of the most important characteristics, and from examining these ‘scrappier’ fossils we can get a much better sense of when and where human body size diversity arose. Before 1.7 million years ago our ancestors were seldom over 5 foot tall or particularly heavy in body mass.
“When this significant size shift to much heavier, taller individuals happened, it occurred primarily in one particular place — in a region called Koobi Fora in northern Kenya around 1.7 million years ago. That means we can now start thinking about what regional conditions drove the emergence of this diversity, rather than seeing body size as a fixed and fundamental characteristic of a species,” said Stock.
Reference:
Manuel Will, Jay T. Stock. Spatial and temporal variation of body size among early Homo. Journal of Human Evolution, 2015 DOI: 10.1016/j.jhevol.2015.02.009
Note: The above story is based on materials provided by University of Cambridge. The original story is licensed under a Creative Commons Licence.
Debris from the 2011 Tohoku earthquake and tsunami. A new study is the first to look at how the earthquake affected the release of halocarbons into the atmosphere. Credit: National Institute for Environmental Studies
Buildings destroyed by the 2011 Tohoku earthquake released thousands of tons of climate-warming and ozone-depleting chemicals into the atmosphere, according to a new study.
New research suggests that the thousands of buildings destroyed and damaged during the 9.0 magnitude earthquake and tsunami that struck Japan four years ago released 6,600 metric tons (7,275 U.S. tons) of gases stored in insulation, appliances and other equipment into the atmosphere.
Emissions of these chemicals, called halocarbons, increased by 21 percent to 91 percent over typical levels, according to the new study accepted for publication in Geophysical Research Letters, a journal of the American Geophysical Union.
The study is the first to look at how the Tohoku earthquake affected the release of halocarbons into the atmosphere and likely one of the first to examine emissions of these gases following a natural disaster, according to the study’s authors.
“What we found is a new mechanism of halocarbon emissions coming from the earthquake,” said Takuya Saito, a senior researcher at the National Institute for Environmental Studies in Tsukuba, Japan, and lead author of the new paper.
Halocarbons released as a result of the earthquake include chemicals that deplete the ozone layer and contribute to global warming — including some gases that are no longer used because of those harmful effects on the environment. These include chlorofluorocarbons like CFC-11, a powerful ozone-depleting chemical used in foam insulation until it was phased out in 1996, and hydrochlorofluorocarbons like HCFC-22, an ozone-depleting refrigerant that is also a powerful greenhouse gas and is in the process of being phased out of use. Among other halocarbons released by the earthquake were hydrofluorocarbons, or HFCs, and sulfur hexafluoride, both potent greenhouse gases.
The emissions of the six halocarbons released from Japan in 2011 are equivalent to the discharge of 1,300 metric tons (1,433 U.S. tons) of CFC-11 alone — equal to the amount of CFC-11s found in 2.9 million refrigerators manufactured before the chemical was banned. The total emissions of the six chemicals are also equivalent to the release of 19.2 million metric tons (21.2 million U.S. tons) of carbon dioxide into the atmosphere — an amount equal to about 10 percent of Japanese vehicle emissions in 2011, according to the study’s authors.
Post-quake surprise
Saito and his colleagues decided to investigate halocarbon emissions and their relationship to the earthquake after ground-based air monitoring stations in Japan recorded surprising high levels of these chemicals. The stations are on Hateruma Island, east of Taiwan; Cape Ochiishi, on the east side of Hokkaido; and Ryori, north of Tokyo on Honshu.
The study’s authors combined these measurements with an atmospheric model and other mathematical methods to figure out that increased emissions from the earthquake were involved, how much of the emissions could be attributed to the disaster and how they compared to previous years.
They found that emissions of all six halocarbons were higher from March 2011 to February 2012, following the earthquake, than they were during the same time the year before the event and during the same period the year after it.
About 50 percent of the halocarbon emissions after the earthquake were of HCFC-22, likely due to damage to refrigerators and air conditioners. Emissions of the gas were 38 percent higher than the years before and after the earthquake. Emissions of CFC-11 were 72 percent higher than emissions before and after the earthquake, likely due to damage to insulation foams used in appliances and buildings, according to the study. Emissions of two types of HFCs — HFC-134a and HFC-32 — rose by 49 percent and 63 percent compared to the years before and after the disaster.
Impacts assessed
The new study also calculates the total impact of the increased emissions on ozone depletion and global warming. The earthquake-triggered surge of halocarbons increased ozone loss from Japanese emissions of those six gases by 38 percent from March 2011 to February 2012 compared to the same time period in the years before and after the event. The amount of heat trapped in the atmosphere because of Japan’s emissions of those six gases rose 36 percent from March 2011 to February 2012 compared to earlier and later years because of the extra emissions from the earthquake, according to the new study.
Saito said the new study shows the importance of including the release of gases from natural disasters in emissions estimates. Although the global effect of one event is small — emissions associated with the Tohoku earthquake accounted for 4 percent or less of global emissions in 2011 — the cumulative effect could be larger, he said. Natural disasters accelerate the release of halocarbons and replacement of these gases could lead to the use of more halocarbons, according to the study.
National halocarbon emissions estimates by the Japanese government did not factor in the release of the chemicals due to the earthquake and are likely underestimating the amount of these substances in the atmosphere, according to Saito. Governments rely on inventories of chemicals and generic data about how they are used to estimate their amounts in the atmosphere — called a “bottom-up” approach” — whereas the new study uses actual measurements of the gases — called a “top-down” approach. “It is apparent that there are unreported emissions,” Saito said.
The new study shows that there could be a need to include the amount of halocarbons released by catastrophic events in emissions estimates, said Steve Montzka, a research chemist at the National Oceanic and Atmospheric Administration in Boulder, Colorado, who was not involved in the research. It also highlights the need for more measurements of halocarbons in the atmosphere, he added, rather than relying on bottom-up emissions estimates from inventories.
“Atmospheric scientists often say that relying solely on bottom-up inventories to tell you how greenhouse gas emissions change is like going on a diet without weighing yourself,” Montzka said.
Reference:
Takuya Saito, Xuekun Fang, Andreas Stohl, Yoko Yokouchi, Jiye Zeng, Yukio Fukuyama, Hitoshi Mukai. Extraordinary halocarbon emissions initiated by the 2011 Tohoku earthquake. Geophysical Research Letters, 2015; DOI: 10.1002/2014GL062814
USGS scientists recount their experiences before, during and after the May 18, 1980 eruption of Mount St. Helens. Loss of their colleague David A. Johnston and 56 others in the eruption cast a pall over one of the most dramatic geologic moments in American history.
The Mariana Trench or Marianas Trench is the deepest part of the world’s oceans. It is located in the western Pacific Ocean, to the east of the Mariana Islands. The trench is about 2,550 kilometres (1,580 mi) long but has an average width of only 69 kilometres (43 mi). It reaches a maximum-known depth of 10,994 m (± 40 m) or 6.831 mi (36,070 ± 131 ft) at the Challenger Deep, a small slot-shaped valley in its floor, at its southern end, although some unrepeated measurements place the deepest portion at 11.03 kilometres (6.85 mi).
At the bottom of the trench the water column above exerts a pressure of 1,086 bars (15,750 psi), over 1000 times the standard atmospheric pressure at sea level. At this pressure the density of water is increased by 4.96%, making 95 litres of water under the pressure of the Challenger Deep contain the same mass as 100 litres at the surface. The temperature at the bottom is 1 to 4 °C.
The trench is not the part of the seafloor closest to the center of the Earth. This is because the Earth is not a perfect sphere: its radius is about 25 kilometres (16 mi) less at the poles than at the equator. As a result, parts of the Arctic Ocean seabed are at least 13 kilometres (8.1 mi) closer to the Earth’s center than the Challenger Deep seafloor.
Xenophyophores have been found in the trench by Scripps Institution of Oceanography researchers at a record depth of 10.6 km (6.6 mi) below the sea surface. On 17 March 2013, researchers reported data that suggested microbial life forms thrive within the trench.
The Mariana Trench is named for the nearby Mariana Islands (in turn named Las Marianas in honor of Spanish Queen Mariana of Austria, widow of Philip IV of Spain). The islands are part of the island arc that is formed on an over-riding plate, called the Mariana Plate (also named for the islands), on the western side of the trench.
Geology
The Mariana Trench is part of the Izu-Bonin-Mariana subduction system that forms the boundary between two tectonic plates. In this system, the western edge of one plate, the Pacific Plate, is subducted (i.e., thrust) beneath the smaller Mariana Plate that lies to the west. Crustal material at the western edge of the Pacific Plate is some of the oldest oceanic crust on earth (up to 170 million years old), and is therefore cooler and more dense; hence its great height difference relative to the higher-riding (and younger) Mariana Plate. The deepest area at the plate boundary is the Mariana Trench proper.
The movement of the Pacific and Mariana plates is also indirectly responsible for the formation of the Mariana Islands. These volcanic islands are caused by flux melting of the upper mantle due to release of water that is trapped in minerals of the subducted portion of the Pacific Plate.
Measurements
The trench was first sounded during the Challenger expedition in 1875, which recorded a depth of 4,475 fathoms (8.184 km). In 1877 a map was published called Tiefenkarte des Grossen Ozeans by Petermann, which showed a Challenger Tief at the location of that sounding. In 1899 USS Nero, a converted collier, recorded a depth of 5269 fathoms (9,636 m, 31,614 ft). Challenger II surveyed the trench using echo sounding, a much more precise and vastly easier way to measure depth than the sounding equipment and drag lines used in the original expedition. During this survey, the deepest part of the trench was recorded when the Challenger II measured a depth of 5,960 fathoms (10,900 m, 35,760 ft) at 11°19′N 142°15′E, known as the Challenger Deep.
In 1957, the Soviet vessel Vityaz reported a depth of 11,034 m (36,201 ft), dubbed the Mariana Hollow.
In 1962, the surface ship M.V. Spencer F. Baird recorded a maximum depth of 10,915 m (35,840 ft), using precision depth gauges.
In 1984, the Japanese survey vessel Takuyō , collected data from the Mariana Trench using a narrow, multi-beam echo sounder; it reported a maximum depth of 10,924 m, also reported as 10,920 ± 10 metres.
Remotely Operated Vehicle KAIKO reached the deepest area of Mariana trench and made the deepest diving record of 10,911 m on March 24, 1995.
During surveys carried out between 1997 and 2001, a spot was found along the Mariana Trench that had depth similar to that of the Challenger Deep, possibly even deeper. It was discovered while scientists from the Hawaii Institute of Geophysics and Planetology were completing a survey around Guam; they used a sonar mapping system towed behind the research ship to conduct the survey. This new spot was named the HMRG (Hawaii Mapping Research Group) Deep, after the group of scientists who discovered it.
On 1 June 2009 sonar mapping of the Challenger Deep by the Simrad EM120 sonar multibeam bathymetry system for deep water (300–11,000 m) mapping aboard the RV Kilo Moana (mothership of the Nereus vehicle), has indicated a spot with a depth of 10,971 m (35,994 ft). The sonar system uses phase and amplitude bottom detection, with an accuracy of better than 0.2% of water depth across the entire swath (implying the depth figure is accurate to less than ± 22 metres).
In 2011, it was announced at the American Geophysical Union Fall Meeting that a US Navy hydrographic ship equipped with a multibeam echosounder conducted a survey which mapped the entire trench to 100 m resolution. The mapping revealed the existence of four rocky outcrops thought to be former seamounts.
The Mariana Trench is a site chosen by researchers at Washington University and the Woods Hole Oceanographic Institution in 2012 for a seismic survey to investigate the subsurface water cycle. Using seismometers and hydrophones the scientists are able to map structures as deep as 60 mi (97 km) beneath the surface.
How deep is the ocean?
The average ocean depth is 2.65 miles.
The average depth of the ocean is about 14,000 feet. The deepest part of the ocean is called the Challenger Deep and is located beneath the western Pacific Ocean in the southern end of the Mariana Trench, which runs several hundred kilometers southwest of the U.S. territorial island of Guam. Challenger Deep is approximately 36,200 feet deep. It is named after the HMS Challenger, whose crew first sounded the depths of the trench in 1875.
