October 22, 2013
If you traveled to the town of Kalgoorlie, in Western Australia, then headed about 25 miles north, you’d eventually reach a grove of large eucalyptus trees, some more than 30 feet tall, scattered across a dusty, arid landscape. Examining the dirt at your feet would reveal no trace of the gold deposits that lie roughly 100 feet underground, due to the thick layers of clay and rock that sit atop the precious metal.
But, scientists recently learned, if you peered closely enough at the eucalyptus trees—specifically, using X-rays to detect nanoparticles—you’d find that there’s gold in them thar leaves. As detailed in a study published today in Nature Communications, a group of researchers from Australia’s Commonwealth Scientific and Industrial Research Organisation has shown that plants can absorb gold particles deep underground and bring it upward through their tissues—a finding that could help mineral exploration companies mine for gold.
“In Australia, we’re faced with this problem of trying to explore through thick layers of sediments and weathered rock to reach valued minerals,” says Melvyn Lintern, an Earth scientist and lead author of the study. “At the same time, we’d previously heard from mining engineers that, in some places, they’d found eucalyptus roots going down to 30 meters [98 feet] or deeper in the mines.” With this observation in mind, and the knowledge that plants can absorb and transport minerals from the surrounding soil and bedrock all the way up to their leaves, Lintern and his colleagues were struck with an idea: Why not test eucalyptus leaves to see if they could indicate underground gold deposits?
To do so, they visited two Australian sites with known gold deposits deep underground (as revealed by exploratory drilling) that were covered by thick layers of rock and on top of which grew tall eucalyptus trees. When they tested leaves that grew on or had fallen from the large trees in both areas, they indeed found minute traces of gold—up to 80 parts per billion, compared with the 2 parts per billion they found in leaves that had grown 650 feet away from the underground deposit.
Other researchers had detected gold particles in plants and leaf litter before, but it was unclear whether they’d been transported all the way from underground deposits. “We were concerned that the gold might have been occurring as dust particles on the outside of these leaves, so it was important for us to locate the gold within the plant,” says Lintern.
His team did so by analyzing the leaves in even further detail (using a specialized X-ray microprobe located at the Australian Synchrotron research facility) and confirmed that the gold particles were located within the plant’s vascular tissue, indicating that they were moving naturally within the leaves. They also conduced greenhouse experiments and found that eucalyptus saplings, grown in soil laced with similar levels of gold, absorbed it and transported detectable levels into their leaves. These separate streams of evidence, they say, shows that the wild eucalyptus trees were indeed sucking up gold from deep underground.
“The eucalyptus acts like a hydraulic pump,” using its roots to suck ground water upward, crucial in an arid environment, Lintern says. “The plants, of course, are searching for water, not gold, but it just so happens that there’s gold dissolved in it.”
The fact that the gold has been found in the leaves, in fact, might be evidence that the eucalyptus is actively trying to get rid of it—after all, it’s a toxic heavy metal—by transporting it to its extremities. Additionally, the gold particles in the leaves were often found located near calcium oxalate crystals, theorized to be part of the removal pathway for toxic chemicals.
Lintern’s group plans to conduct further research into which plants are capable of transporting gold particles in this way and what environmental factors affect the rate of uptake. Mining companies in Canada, he mentions, have already toyed with the idea of using plants as mineral indicators, so this first scientific evidence for the process is likely to accelerate adoption of the method.
“Essentially, we’re tapping into a natural process,” Lintern says. In an age when most of the readily accessible gold near the planet’s surface has been mined, it makes sense to harness the natural mineral exploration plants are already engaging in when they drive their roots deep into the ground. Doing so might even reduce the number of exploratory mines we’re forced to drill—and consequently, lead to less environmental destruction of these plants’ habitats as a result of mining.
October 14, 2013
In the 20 years since the movie Jurassic Park fantasized about how dinosaurs could be cloned from blood found in ancient amber-trapped mosquitoes, fossil collectors have been on the hunt for a similar specimen. Over the years, a few different groups of scientists have claimed to find a fossilized mosquito with ancient blood trapped in its abdomen, but each of these teams’ discoveries, in turn, turned out to be the result of error or contamination.
Today, it was announced that we finally have such a specimen, a blood-engorged mosquito that’s been preserved in shale rock for around 46 million years in northwestern Montana. The most astounding thing about the discovery? It was made three decades ago by an amateur fossil hunter—a geology graduate student named Kurt Constenius—then left to sit in a basement, and only recognized recently by a retired biochemist named Dale Greenwalt who’s been working to collect fossils in the Western U.S. for the Smithsonian Museum of Natural History.
The specimen, described in a paper Greenwalt published with museum researchers and entomologist Ralph Harbach today in the Proceedings of the National Academy of Sciences, is trapped in stone, not amber, and (unfortunately for Jurassic Park enthusiasts) it’s not old enough to be filled with dinosaur blood. But it is the first time we’ve found a fossilized mosquito with blood in its belly.
The rock-encased specimen was originally excavated sometime during the early 80s, when Constenius, then pursuing a master’s degree in geology from the University of Arizona, found hundreds of fossilized insects during weekend fossil-hunting trips with his parents at the Kishenehn Formation in northwestern Montana, near Glacier National Park. In the years since, they’d simply left the fossils sitting in boxes in their basement in Whitefish, Montana and largely forgotten about them.
Enter Greenwalt, who began volunteering at the museum in 2006, cataloging specimens for the paleobiology department. In 2008, he embarked on his own project of collecting fossils from the Kishenehn every summer, in part because he’d read in an insect evolution textbook an offhand mention of Constenius’ discoveries, which had never been rigorously described in the scientific literature.
In the years since, Greenwalt has collected thousands of specimens from 14 different orders of insects. The collection site is remote—he has to raft the Flathead River that runs along the border of the park to a place where the river has cut down through layers of rock of the Kishenehn Formation, which includes shale that formed the bottom of a lake during the Eocene epoch, some 46 million years ago.
“It is a fantastic fossil insect site, arguably one of the best in the world,” he says, noting that a rare combination of circumstances—thin layers of fine-grained sediment and a lack of oxygen—led to a “mind-boggling degree of preservation.” Working there, he’s made a number of significant finds, collecting specimens that led to the description of two new insect species (pdf).
After Greenwalt met the Constenius family in Whitefish and described his work, they decided to donate their fossil collection to the museum. When he began cataloging the boxes the fossils and came across this particular specimen, “I immediately noticed it—it was obvious that it was different,” he says. He suspected that the mosquito’s darkly opaque abdomen, trapped in a thin piece of shale, might contain 46-million-year old blood.
Staff from the museum’s mineral sciences lab used a number of techniques to scan the specimen up close, including energy dispersive X-ray spectroscopy. “The first thing we found is that the abdomen is just chock full of iron, which is what you’d expect from blood,” Greenwalt says. Additionally, analysis using a secondary ion mass spectrometer revealed the presence of heme, the compound that give red blood cells their distinctive color and allows them to carry oxygen throughout the body. Other tests that showed an absence of these compounds elsewhere in the fossil.
The findings serve as definitive evidence that blood was preserved inside the insect. But at this point, scientists have no way of knowing what creature’s fossilized blood fills the mosquito’s abdomen. That’s because DNA degrades way too quickly to possibly survive 46 million years of being trapped in stone (or in amber, for that matter). Recent research had found it has a half-life of roughly 521 years, even under ideal conditions.
This means that even if we miraculously had some DNA of the ancient creature, there are currently a ton of technical problems that prevent the cloning similar to that in Jurassic Park from becoming a reality. Assembling a full genome from DNA fragments requires us to have an understanding of what the whole genome looks like (which we don’t have in this case), and turning that into a living, breathing animal would necessitate putting that DNA into an ovum of a living species very closely related to the mystery creature that we don’t know in the first place.
So, alas, no resurrected ancient creatures will roam free thanks to this new find. Still, the find is scientifically significant, helping scientists better understand the evolution of blood-feeding insects. Previously, the closest thing to a blood-engorged mosquito that scientists had found was a mosquito with remnants of the malaria parasite inside its abdomen (pdf). Though that provides indirect evidence that mosquitoes fed on blood 15-20 million years ago, this new discovery represents the oldest direct evidence of blood-sucking behavior. It also shows for the first time that biological molecules such as heme can survive as part of the fossil record.
October 10, 2013
The star GD61 is a white dwarf. As such, it’s insanely dense—similar in diameter to Earth, but with a mass roughly that of the Sun, so that a teaspoon of it is estimated to weigh about 5.5 tons. All things considered, it’s not a particularly promising stellar locale to find evidence of life.
But a new analysis of the debris surrounding the star suggests that, long ago, GD61 may have provided a much more hospitable environment. As part of a study published today in Science, scientists found that the crushed rock and dust near the star were once part of a small planet or asteroid made up of 26 precent water by volume. The discovery is the first time we’ve found water in a rocky, Earth-like planetary body (as opposed to a gas giant) in another star system.
“Those two ingredients—a rocky surface and water—are key in the hunt for habitable planets,” Boris Gänsicke of the University of Warwick in the UK, one of the study’s authors, said in a press statement. “So it’s very exciting to find them together for the first time outside our solar system.”
Why was water found in such a seemingly unhospitable place? Because once upon a time, GD61 wasn’t so different from our Sun, scientists speculate. But roughly 200 million years ago, when it exhausted its supply of fuel and could no longer sustain fusion reactions, its outer layers were blown out as part of a nebula, and its inner core collapsed inward, forming a white dwarf. (Incidentally, this fate will befall an estimated 97 percent of the stars in the Milky Way, including the Sun.)
When that happened, the tiny planet or asteroid in question—along with all the other bodies orbiting GD61—were violently knocked out of orbit, sucked inward, and ripped apart by the force of the star’s gravity. The clouds of dust, broken rock and water that the scientists recently discovered near the star are the remnants of these planets.
Even in its heyday, the watery body was probably still very small—perhaps comparable in size to our solar system’s dwarf planet Ceres, which orbits in the asteroid belt and is about .015 percent the mass of Earth. Additionally, like Ceres, the ancient planet or asteroid was extremely water-rich (26 percent water, far more than Earth’s .023 percent), and this water was similarly constituted as ice locked within a rocky crust.
To find all this out, the group of scientists (which also includes Jay Farihi of the University of Cambridge and Detlev Koester of the University of Kiel) used observations from two sources: a spectrograph on board the Hubble Space Telescope, through which they obtained data on ultraviolet light emitted by GD61, and a telescope at the W.M. Keck Observatory on Mauna Kea on Hawaii.
By looking at the light emitted from the star, which glows in certain patterns depending on the chemical signatures of gases present, they were able to determine the proportions of a number of elements (including oxygen, magnesium, aluminum, silicon, calcium and iron) contained within the cloud of dust that surrounds it. Using computer simulations of this stellar atmosphere, they were able to rule out a number of alternate possibilities that could have accounted for the abundance of oxygen, leaving only the explanation that it was brought there in water form.
Based on the amount of water and rocky minerals detected in the star’s atmosphere—and assuming it all came from one body—scientists speculate that the small planet or asteroid ripped up by the white dwarf was at least 56 miles in diameter, but perhaps much larger.
Although the star certainly isn’t home to any life at the moment due to its relatively cold temperature, the finding makes it seem more likely that other exoplanets contain water, which is necessary for life as we know it. Many scientists have speculated that small planets and asteroids like Ceres delivered water to Earth in the first place, so finding evidence of a watery body like this in another star system raises the possibility that the same process may have brought water to an Earth-sized planet elsewhere too.
“The finding of water in a large asteroid means the building blocks of habitable planets existed—and maybe still exist—in the GD 61 system, and likely also around a substantial number of similar parent stars,” Farihi said. “These water-rich building blocks, and the terrestrial planets they build, may in fact be common.”
October 1, 2013
Last Tuesday, a 7.7-magnitude earthquake hit Pakistan, causing widespread destruction, the creation of a new island off the country’s coastline and at least 515 deaths.
Of course, there’s nothing we can do to prevent such disasters—earthquakes result from the shifting and collision of enormous, continent-scale tectonic plates over which we have no control. If we know a massive quake is about to strike, though, there may be measures we can take to better protect ourselves.
But how could we possibly know when a quake is about to hit? Seismologists are extremely good at characterizing the overall hazards that those living in fault zones face, but they’re far away from being able (and may never have the ability) to predict exactly when an earthquake will strike.
Undeterred, several different teams of scientists are hatching plans for a new kind of solution. And the key to their success may may be the smartphone in your pocket.
Their idea takes advantage of the fact that most new smartphones include a tiny chip called an accelerometer. These chips measure the movement of the phone in three directions (up-down, left-right, and backward-forward) to customize your experience as you use the phone—for example, rotating the display if you turn the device.
As it happens, seismometers (the large, expensive instruments used by geologists to detect and measure earthquakes) do essentially the same thing, albeit with much more accuracy. Still, the tiny accelerometers we already carry around with us all the time could allow scientists to gather much more real-time data than is currently available—there are countless times more smartphones than seismometers, they’re much cheaper and they’re already deployed in a wide range of locations—if they can actually measure earthquake movement with sufficient precision.
Recently, Antonino D’Alessandro and Giuseppe D’Anna, a pair of seismologists at Italy’s Istituto Nazionale di Geofisica e Vulcanologia, set out to resolve this question. To assess the accelerometers—specifically, the LIS331DLH MEMS accelerometer used in iPhones—the duo placed five iPhones on a vibrating table in a variety of positions (flat, angled on top of a wedge-shaped piece, and vertical) and compared the data they recorded with a professional-quality earthquake sensor for reference.
Their results, published Sunday in the Bulletin of the Seismological Society of America, showed that the iPhone accelerometers performed even better than they expected. “When we compared the signals, we pleasantly surprised by the result—the recordings were virtually identical,” D’Alessandro says. “An accelerometer that costs a few dollars was able to record acceleration with high fidelity, very similar to a professional accelerometer that costs a few thousand.”
There are some limitations: the iPhone accelerometers aren’t as sensitive to weak vibrations, so during the tests, they were only able to record movements that correspond to earthquakes that would register as magnitude 5 or higher. But ”these limits will be overcome in the near future,” says D’Alessandro. “Because these chips are widely used in laptops, games controllers and mobile phones, research into improving them is going on around the world.”
The next step would be developing software to allow normal users to harness these accelerometers’ capabilities, turning their smartphones into mobile earthquake sensing systems. Last December, Berkeley researchers announced plans to develop an app that would allow users to donate their accelerometer data to earthquake research. Stanford’s Quake-Catcher Network and Caltech’s Community Seismic Network—both of which use small purpose-built seismometers that are distributed to volunteers and plugged into their computers—could serve as a model for this sort of network.
Once in place, the network would be able to gather a huge amount of data from thousands of geographically-dispersed users, allowing researchers to see how quakes move with finer resolution. If enough phones are on this network, emergency workers may be able to quickly gauge where they could most efficiently devote their time after a quake hits.
But how do you go from documenting earthquakes to warning people about when dangerous shaking will occur? As The Atlantic points out, the key is that earthquakes are actually comprised of two types of waves that ripple through the earth: P-waves, which arrive first and are difficult for humans to sense, and S-waves, which typically come a few seconds later and cause the majority of the physical damage.
If we had software installed on our phones that automatically detected strong P-waves and sounded an alarm, we might have a few scant seconds to take cover before the S-waves hit (officials recommend dropping to the ground, huddling under a stable table or desk and getting away from windows and doors). It’s not much, but in some cases, a just a few crucial seconds of warning could make all the difference.
September 26, 2013
Some 46 Martian days after landing on Mars in August 2012, after traveling nearly 1,000 feet from its landing site, Curiosity came upon a pyramid-shaped rock, roughly 20 inches tall. Researchers had been looking for a rock to use for calibrating a number of the rover’s high-tech instruments, and as principal investigator Roger Wiens said at a press conference at the time, “It was the first good-size rock that we found along the way.”
For the first time, scientists used the rover’s Hand Lens Imager (which takes ultra-high resolution photos of a rock’s surface) and the Alpha Particle X-ray Spectrometer (which bombards a rock with alpha particles and X-rays, kicking off electrons in patterns that allow scientists to identify the elements locked within it). They also used the ChemCam, a device that fires a laser at a rock and measures the abundances of elements vaporized.
Curiosity, for its part, commemorated the event with a pithy tweet:
I did a science! 1st contact science on rock target Jake. Here’s an action shot pic.twitter.com/pzcgH6Bk
— Curiosity Rover (@MarsCuriosity) September 22, 2012
A year later, the Curiosity team’s analysis of the data collected by these instruments, published today in Science, shows that they made a pretty lucky choice in finding a rock to start with. The rock, dubbed “Jake_M” (after engineer Jake Matijevic, who died a few days after Curiosity touched down), is unlike any rock previously found on Mars—and its composition intriguingly suggests that it formed after molten rock cooled quickly in the presence of underground water.
The new discovery was published as part of a special series of papers in Science that describe the initial geologic data collected by Curiosity’s full suite of scientific instrumentation. One of the other significant findings is a chemical analysis of a scoop of Martian soil—heated to 835 degrees Celsius inside the Sample Analysis at Mars instrument mechanism—showing that it contains between 1.5 and 3 percent water by weight, a level higher than scientists expected.
But what’s most exciting about the series of findings is the surprising chemical analysis of Jake_M. The researchers determined that it is likely igneous (formed by the solidification of magma) and, unlike any other igneous rocks previously found on Mars, has a mineral composition most similar to a class of basaltic rocks on Earth called mugearites.
“On Earth, we have a pretty good idea how mugearites and rocks like them are formed,” Martin Fisk, an Oregon State University geologist and co-author of the paper, said in a press statement. “It starts with magma deep within the Earth that crystallizes in the presence of one to two percent water. The crystals settle out of the magma, and what doesn’t crystallize is the mugearite magma, which can eventually make its way to the surface as a volcanic eruption.” This happens most frequently in underground areas where molten rock comes into contact with water—places like mid-ocean rifts and volcanic islands.
The fact that Jake_M closely resembles mugearites indicates that it likely took the same path, forming after other minerals crystallized in the presence of underground water and the remaining minerals were sent to the surface. This would suggest that, at least at some time in the past, Mars contained reserves of underground water.
The analysis is part of a growing body of evidence that Mars was once home to liquid water. Last September, images taken by Curiosity showed geologic features that suggested the one-time presence of flowing water at the surface. Here on Earth, analyses of several meteorites that originated on Mars have also indicated that, at some point long ago, the planet held reserves of liquid water deep underground.
This has scientists and members of the public excited, of course, because (at least as far as we know) water is a necessity for the evolution of life. If Mars was once a water-rich planet, as Curiosity’s findings increasingly suggest, it’s possible that life may have once evolved there long ago—and there may even be organic compounds or other remnants of life waiting to be found by the rover in the future.