December 9, 2013
Shortly after NASA’s Curiosity rover landed on Mars in August 2012, the scientists guiding the device decided to make a temporary detour before heading to the mission’s ultimate destination, Mount Sharp. Last spring, they guided the six-wheeled machine towards Yellowknife Bay, a slight depression with intriguingly lighter-toned sedimentary rocks, and drilled its first two holes in Martian rock in order to collect samples.
Afterward, as Curiosity drove away from Yellowknife Bay, onboard equipment ground the rock samples to a fine dust and chemically analyzed their content in extreme detail to learn as much as possible about the site. Today, the results of that analysis were finally published in a series of articles in Science, and it’s safe to say that the scientists probably don’t regret making that brief detour. Yellowknife Bay, they discovered, was likely once home to a calm freshwater lake that lasted for tens of thousands of years, and theoretically had all the right ingredients to sustain microbial life.
“This is a huge positive step for the exploration of Mars,” said Sanjeev Gupta, an Earth scientist at Imperial College London and a member of the Curiosity team, in a press statement on the discovery. “It is exciting to think that billions of years ago, ancient microbial life may have existed in the lake’s calm waters, converting a rich array of elements into energy.”
Previously, Curiosity found ancient evidence of flowing water and an unusual type of rock that likely formed near water, but this is the strongest evidence so far that Mars may have once sustained life. The chemical analysis of the two rocks (named “John Klein” and “Cumberland”) showed that they were mudstones, a type of fine-grained sedimentary rock that generally forms at the bottom of a calm body of water, as small sediment particles gradually settle on one another and are eventually cemented together.
Isotope analysis indicated that these rocks formed sometime between 4.5 and 3.6 billion years ago, either during Mars’ Noachian period (in which the planet was likely much warmer, had a thicker atmosphere and may have had abundant surface water) or early on in its Hesperian period (in which it shifted to the dry, colder planet we see currently).
Additionally, a number of key elements for the establishment of life on Earth—including carbon, hydrogen, oxygen, sulfur, nitrogen and phosphorous—were found in detectable quantities in the rocks, and chemical analysis indicated that the water was likely of a relatively neutral pH and low in salt content. All of these discoveries increase the chance that the ancient lake could have served as a habitat for living organisms.
The scientists hypothesize that the microorganisms most likely to live in this environment would have been chemolithoautotrophs, a type of microbe that derives energy by breaking down rocks and incorporates carbon dioxide from the air. On Earth, these types of organisms are most often found near hydrothermal vents on the ocean floor, where they thrive off chemicals emitted into the water.
Obviously, this isn’t direct proof of life, but rather circumstantial evidence that it may have once existed. Still, it’s yet another vindication of Curiosity’s mission, which is to determine the planet’s habitability. Over the coming months and years, the scientists guiding the rover plan to keep sampling sedimentary rocks on the planet’s surface, hoping to find further evidence of potentially-habitable ancient environments and perhaps even direct evidence of now-extinct living organisms.
For more, head over to NASA’s webcast of the press conference announcing the findings, which occurred today at noon EST.
December 5, 2013
The magnitude 9.0 Tohoku-Oki earthquake that struck Japan on 11 March 2011, killing more than 15,000 people and setting off a devastating tsunami that the nation is still working to recover from, brought up a lot of troubling questions. For instance,
what made such a powerful earthquake possible, and could it happen again in Japan or somewhere else?
An international group of scientists that drilled miles beneath the Pacific Ocean and into the earthquake fault now have answers to these questions, and they report their findings in a trio of papers published today in Science.
The epicenter of the 2011 quake was in an unusual spot, about 130 kilometers east of Sendai, Japan, just off the northern coast of that nation
. In this area, a subduction zone, the Pacific plate is diving beneath the Eurasian plate. Strong earthquakes are possible here, but scientists hadn’t thought that there was enough energy to produce one larger than magnitude 7.5. They were wrong, and they’ve been interested in finding out more about what made the fault capable of producing such a large quake.
A little over a year after the earthquake, the deep sea drilling vessel Chikyu was tasked with the mission to drill into the fault off the Japanese coast and install a temperature observatory. By taking the temperature of a fault after an earthquake, scientists can measure how much energy was released in the quake and calculate a fault’s friction—how easily the rocks rub against each other.
“One way to look at the friction of these big blocks is to compare them to cross-country skis on snow,” Robert Harris, a study co-author and geophysicist at Oregon State University, said in a statement. “At rest, the skis stick to the snow and it takes a certain amount of force to make them slide. Once you do, the ski’s movement generates heat and it takes much less force to continue the movement…. The same thing happens with an earthquake.”
Getting that temperature measurement was tricky. The Chikyu team had to drill 850 meters into the seafloor, which itself was 6,900 meters below the ocean’s surface. They had to deal with bad weather, and the fault itself was still shifting, putting the instruments at risk.
The difficult work paid off, though, and it revealed residual heat from the earthquake, from which the scientists could calculate the fault’s friction, which was very low. Bottom line: “The Tohoku fault is more slippery than anyone expected,” Emily Brodsky, a study co-author and geophysicist at the University of California, Santa Cruz, said in another statement.
The slippery nature of the fault helps to explain some characteristics of the 2011 quake. The fault slipped an unprecedented 50 meters and the rupture, which began deep underground, reached the surface where it caused a sudden disturbance in the ocean and set off the tsunami.
The drilling and laboratory tests also revealed another characteristic of the fault that made it so dangerous. The low friction can be attributed to incredibly fine clay sediment within the fault. “It’s the slipperiest clay you can imagine,” Christie Rowe, a study co-author and geologist at McGill University, said in a statement. “If you rub it between your fingers, it feels like a lubricant.” Incidentally, the area between the Pacific and Eurasian plates that experiences slip is also very thin, less than five meters across, which would make it the thinnest known fault zone on the planet.
Measuring the earthquake’s thermal signal was a first for science. It “was a major accomplishment,” Harris said, “but there is still a lot we don’t yet know.” For example, researchers don’t yet know how generalizable these results are to other subduction zones across the world or what effect the thinness of fault zones has on earthquake hazards. Nonetheless, the drilling results “suggest that the shallow megathrust at the Japan Trench has special traits not seen in many other subduction zones,” Kelin Wang of Natural Resources Canada and Masataka Kinoshita of the Japan Agency for Marine-Earth Science and Technology—the agency that runs the Chikyu—wrote in an accompanying Perspectives article.
Similar conditions may be rare, but they do exist in some places of the north Pacific, such as the Kamchatka Peninsula in Russia and the Aleutian Islands in Alaska, notes Rowe.Deep sea drilling shows that these regions have that same usually slippery clay that lowered the friction in the Japan fault.
But the fact that the unusual circumstances of the Japan fault may be rare shouldn’t put scientists, or the public, at ease, Wang and Kinoshita say. Such huge, shallow slip isn’t necessary for a devastating tsunami to form, and it wasn’t what caused either the 2010 Chile tsunami that destroyed 370,000 homes or the 2004 Indian Ocean tsunami that killed nearly 230,000 people. “It’s hard to say how generalizable these results are until we look at other faults,” Brodsky added. “But this lays the foundation for a better understanding of earthquakes and, ultimately, a better ability to identify earthquake hazards.”
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 2, 2013
Editor’s Note, Oct. 9: Based on several comments that mentioned that the Josephine Brine Treatment Facility stopped treating fracking wastewater in 2011, we did a bit of digging and found that the treated water downstream from the plant still showed signatures that fresh fracking water had run through it, according to the study’s authors. The post has been revised with this information, along with the fact that treatment does remove a good bit of contamination.
In the state of Pennsylvania, home to the lucrative Marcellus Shale formation, 74 facilities treat wastewater from the process of hydraulic fracturing (a.k.a. “fracking”) for natural gas and release it into streams. There’s no national set of standards that guides this treatment process—the EPA notes that the Clean Water Act’s guidelines were developed before fracking even existed, and that many of the processing plants “are not properly equipped to treat this type of wastewater”—and scientists have conducted relatively little assessment of the wastewater to ensure it’s safe after being treated.
Recently, a group of Duke University scientists decided to do some testing. They contacted the owners of one treatment plant, the Josephine Brine Treatment Facility on Blacklick Creek in Indiana County, Pennsylvania, but, “when we tried to work with them, it was very difficult getting ahold of the right person,” says Avner Vengosh, an Earth scientist from Duke. “Eventually, we just went and tested water right from a public area downstream.”
Their analyses, made on water and sediment samples collected repeatedly over the course of two years, were even more concerning than we’d feared. As published today in the journal Environmental Science and Technology, they found elevated concentrations of the element radium, a highly radioactive substance. The concentrations within sediments in particular were roughly 200 times higher than background levels. In addition, amounts of chloride and bromide in the water were two to ten times greater than normal.
This is despite the fact that treatment actually removes most of the contaminants from the wastewater–including 90 percent of the radium. “Even if, today, you completely stopped disposal of the wastewater,” Vengosh says, there’s enough contamination built up in sediments that “you’d still end up with a place that the U.S. would consider a radioactive waste site.”
In recent years, the use of fracking to extract natural gas from shale formations has boomed in several areas, most notably Pennsylvania’s Marcellus Shale, which has been called “the Saudi Arabia of natural gas.” The process involves injecting mix of water, sand and proprietary chemicals deep into rock at high pressure, causing the rock to fracture and allowing methane gas to seep upward for extraction.
Much of the concern over fracking has related to the seepage of these chemicals or methane from drilling wells into groundwater or the fact that high-pressure injection can trigger earthquakes, but the wastewater recently tested presents a separate, largely overlooked problem.
Between 10 and 40 percent of fluid sent down during fracking resurfaces, carrying contaminants with it. Some of these contaminants may be present in the fracking water to begin with. But others are leached into the fracking water from groundwater trapped in the rock it fractures.
Radium, naturally present in the shales that house natural gas, falls into the latter category—as the shale is shattered to extract the gas, groundwater trapped within the shale, rich in concentrations of the radioactive element, is freed and infiltrates the fracking wastewater.
Other states require this wastewater to be pumped back down into underground deposit wells sandwiched between impermeable layers of rock, but because Pennsylvania has few of these cavities, it allows fracking wastewater to be processed by normal wastewater treatment plants and released into rivers.
In 2011, Pennsylvania Department of Environmental Protection (PADEP) issued a recommendation that plants, including Josephine, voluntarily stop treating fracking wastewater. But Jim Efstathiou Jr. at Bloomberg News reports that, even though spokespeople at PADEP and Josephine say that the plant has stopped treating fracking wastewater, those claims are “contradicted by today’s study, which shows that the Josephine plant continued to treat Marcellus Shale wastewater through the beginning of this year,” according to Vengosh.
“Based on the isotopes that we measured we can see that the effluent that’s coming from Josephine in the last three years, including two months ago, still has the fingerprint of the Marcellus,” Vengosh told Efsathiou.
The treatment plants, many scientists note, are not designed to handle the radioactive elements present in the wastewater. Neither are they required to test their effluent for radioactive elements. As a result, many researchers have suspected that the barely-studied water they release into local streams retains significant levels of radioactivity.
This new work confirms that suspicion for at least one plant—which as about an hour east of Pittsburgh, and releases effluent into the watershed that supplies the city’s drinking water—and Vengosh believes that the findings would likely be similar for many of the other facilities in Pennsylvania. Especially concerning is the fact that, apart from in the water, the team found high levels of radioactivity accumulating on the sediments at the bottom of the stream over time. Radium has a half-life of 1600 years, so unless these sediments are removed, they’ll keep releasing radiation into the water for an extremely long period.
In addition, the high levels of bromide found in the wastewater is a concern, because even in slight quantities, the compound can trigger the formation of a toxic class of chemicals called halomethanes when it’s combined with chlorine. This is a problem because in rural areas, many residents treat well water by chlorinating it.
The study—which is part of a larger Duke project studying the effect of fracking on water—doesn’t show that fracking is inherently unsafe, but does show that without proper controls, the wastewater being dumped into the environment daily represents a very real danger for local residents.
Vengosh notes that there are better methods of treating fracking wastewater (he points to the plants operated by Eureka Resources as a model for adequately removing radioactivity), but these are more expensive to operate. But currently, without the push of federal regulations, companies looking to dispose of wastewater have no incentive to pay for this type of solution.