Courtesy NOAANitrogen is an essential nutrient for plants. So how can nitrogen limit plant growth, given that nitrogen comprises 79 percent of the atmosphere? But atmospheric nitrogen is composed of molecules consisting of two atoms of nitrogen and this form of nitrogen cannot be used by plants.
Farmers have for centuries spread animal manure on fields or plowed under leguminous crops (such as alfalfa which has microbial communities living on its roots that fix nitrogen) to add useful, reactive forms of nitrogen to soils. German ingenuity in the early 20th century invented an industrial process that made it possible for the first time to manufacture plant-usable forms of nitrogen, which made possible the artificial fertilizing of crops.
Manmade production of ammonia and nitrate fertilizers has exploded in recent decades and now vastly exceeds the amount of atmospheric nitrogen converted into reactive nitrogen by microbial organisms around the world. At the same time, the burning of ever-increasing quantities of coal, oil and natural gas converts some atmospheric nitrogen into oxides of nitrogen (NOx). NOx emissions can both increase crop growth and diminish it because NOx gases help catalyze the formation of ground-level ozone and this gas is toxic to plant life.
The huge increases of human-produced forms of nitrogen that are applied to croplands and that are released into the atmosphere and eventually settle out have many unintended consequences. In particular, excess nitrogen washes off of agricultural and urban landscapes and is accelerating the destructive growth of algae in lakes, rivers and coastal estuaries around the world.
The connections between manmade carbon dioxide emissions and climate change are quite worrying and receive much scientific and media attention. Nitrogen pollution receives much less notice but is a dramatic example of how human activities now dominate many of the chemical, physical and biological processes that make this plant so amenable to human life.
Courtesy Mark RyanI recently attended a geology seminar sponsored by the Geological Society of Minnesota. The event took place at Macalester College in St. Paul, and was led by Jeff Thole, laboratory supervisor and instructor in the college's Geology Department. Jeff is extremely knowledgeable and enthusiastic about geology, and in the course of cramming a semester's worth of geology into the two hour lab, he mentioned that he had in his office one of the oldest rocks in the world: a nice chunk of Acasta gneiss. After finishing his talk about the rock cycle, and as everyone began examining the variety of rock types spread out on lab tables in several rooms, Jeff brought out the chunk of ancient gneiss for everyone to see.
Found on an island in the extreme and very isolated northern regions of Canada's Northwest Territories, the Acasta gneiss has been radiometrically dated to be upwards to 4.03 billion years old! That's a number that's not very easy to comprehend. The Earth itself is estimated to be just a half-billion years older, so the Acasta gneiss (pronounced nice) is some of the very earliest crustal rock still existing on Earth's ever-changing surface. For a rock unit to withstand 4 billion years of the rock cycle - where the forces of erosion and plate tectonics are constantly at work wearing down, reworking and remelting rocks - that's quite a feat if you think about it.
To give you a better idea of the vast amount of time we're talking about here, let's first reduce it to a more comprehendible time-frame. If you were able to take a single photograph of the Earth each year for those 4 billion years (4,000,000,000 photos) and then made a time-lapse video of all those photos (at 30 frames/photos per second), and started watching the video today, it would take you more than 4 years of constant, around-the-clock viewing to watch it from start to finish. You'd still be watching it in 2017, when non-avian dinosaurs suddenly go extinct about three-and-a-half weeks before the end of the video. We modern humans wouldn't appear for the first time until sometime in the show's last couple hours.
Courtesy D-Maps.comBut back to the rock itself. The ancient gneiss is named after the Acasta River, located east of Great Bear Lake, where the outcrop was first found in the 1980s. The exposure is about 300 kilometers (180 miles) from Yellowknife, so the only practical way to get there is by float plane.
Composed mostly of the minerals quartz and feldspar, the Acasta gneiss was formed during the Hadean, the earliest eon in Earth's history. Its composition leads geologists to surmise that it was probably formed from highly metamorphosed granite subjected to unimaginable heat and pressure. The exact origin of that granite is unknown, but its presence indicates continental crust (and surface water) were probably already present in those very ancient times.
AGE BEFORE BEAUTY
Courtesy Mark RyanIt may interest you to know that Minnesota has its own ancient gneisses exposed in outcrops in the Minnesota River Valley. The most well-known is the gneiss that's quarried around the town of Morton, Minnesota. At nearly 3.6 billion years old, Morton gneiss is not quite as ancient as the Acasta rock but what it lacks in age it makes up for in beauty. Known in the construction trade as Rainbow Granite, polished panels of the banded and severely swirled Archean-aged-aged migmatitic gneiss can be found decorating building facades throughout the country.
TECTONIC VS MARKET FORCES
An enterprising miner from Yellowknife has filed a claim on the Acasta gneiss site, and has been trying to market the ancient rock. This doesn't set well with many in the geological community, who think the rare outcrop should be preserved for scientific study. They also say the prospector could be misrepresenting the public since not all the rock in the exposure dates back to 4 billion years, and it's very expensive to validate the age of any one piece.
THE DATING GAME
So how exactly has the Acasta gneiss been dated so precisely? Zircon crystals found in the rock's mineral structure trap uranium in their lattices when they form and can act as timekeepers through measuring the decay of the uranium into lead. The half-life of uranium is a known number (4.47 billion years for U-238; 704 million years for U-235), so measuring the ratio between number of parent atoms (uranium) to the number of daughter atoms (lead) allows for a very precise estimation of age. But even zircon crystals aren't immune from 4 billion years of exposure to the elements. Things like naturally occurring radiation can damage or alter them and thus skew the measurements. But by using an instrument called the Sensitive High-Resolution Ion Microprobe (aka SHRIMP) researchers are able to focus a beam of oxygen ions on a tiny unaffected segment of the zircon' s surface, remove atoms from it, and then analyze their isotopic composition. The SHRIMP was developed at Australian National University.
Jeff Thole's sample was given to him by a geologist from the Geological Survey of Canada, which purchased a SHRIMP and used it to date the Acasta rocks. It should be noted that an older Canadian rock unit supposedly exists in the greenstone belt east of Hudson Bay, but there's still some contention regarding this, since the method of radiometric dating isn't the same that was used to date Acasta samples.
Whether the Acasta gneiss is the remaining crust of a protocontinent that existed when the Earth was still a relatively young, hot mass of accreted material remains a mystery at this point, but scientist named the time the Hadean for good reason: back then it must have been literally Hell on Earth.
Courtesy Peabody Museum of Natural History, Yale UniversityOn this day in 1877, railroad worker William Harlow Reed came over a ridge-top with the remains of a freshly killed antelope slung over his shoulder, and spotted huge fossilized bones exposed on the side of the steep bluff located a half-mile south of Como Station, a desolate railroad stop on the High Plains of Wyoming. It was a discovery that would forever change his life.
Reed and station master, William Carlin, began collecting up as much as they could, dreaming of money and employment other than railroad work. They waited several months before announcing the discovery in a letter to Yale professor Othniel C. Marsh, at the time one of America's prominent paleontologists. When a crate of bones - along with the guarantee of many more - arrived at Yale, Marsh realized they were dinosaur remains and hired both men to excavate and send him as much as they could, and to keep out any interlopers to his claim. Marsh knew if he could keep it secret - at least for a short time - the fossils at Como Bluff could give him a huge advantage in his rivalry with Philadelphia paleontologist, Edward Drinker Cope, and their notorious Bone Wars.
Courtesy Mark RyanThe dinosaur-rich strata at Como Bluff (the Morrison Formation) are found in the exposed flanks of an anticline (an upward fold), the center of which has been carved out by erosion [see diagram]. All three periods of the Mesozoic Era (Triassic, Jurassic, Cretaceous) are represented in the rock layers found there. Besides dinosaurs, fossils of fish, crocodiles, flying and swimming reptiles have also been found there. A significant number of important Late Jurassic mammalian fossils were discovered and collected by William Reed from Quarry 9 on the east end of Como. Reed also discovered and removed the great Brontosaurus excelsus skeleton that stands today in Yale's Peabody Museum.
Courtesy Peabody Museum of Natural History, Yale UniversityIn the years following its discovery hundreds of tons of dinosaur remains quarried at Como Bluff were shipped to Yale and other institutions pushing America into the forefront of vertebrate paleontology, and heavily influencing how museums would be constructed throughout the world.
Courtesy Mark RyanThe dinosaur halls at the American Museum of Natural History have several mounted specimens found at Como Bluff as does the Smithsonian in our nation's capitol. Well-known genera like Allosaurus, Diplodocus, Apatosaurus, Stegosaurus and Camptosaurus are just a few of the dinosaurs pulled from the mudstones and sandstones at Como Bluff. In the early 20th century it was thought that Como had exhausted its supply of dinosaur remains and exploration there for the most part tapered off for several decades. But in recent years, paleontologist Robert Bakker has been re-examining the quarries and uncovering additional secrets still buried in the Jurassic bluffs at Como.
Courtesy Mark RyanWilliam Reed worked for Marsh for several more years and the two men remained friends until the Yale professor's death in 1899. Reed continued in the field of paleontology, working independently, and for a time with the American Museum of Natural History in New York, and the Carnegie Museum in Pittsburgh. He finished out his career as a popular geology professor and museum curator at the University of Wyoming, just sixty miles from Como Bluff, the great dinosaur graveyard that changed not only the course his life but also that of American paleontology.
Como Bluff was added to the National Register of Historic Places in 1973. It's also been designated as one of Wyoming's National Natural Landmarks by the National Park Service.
This amazing video from NASA (via EarthSky) shows an incredibly gigantic eruption on the Sun's surface that produced three different types of events: a solar flare, a coronal mass ejection (CME), and a really interesting and rare phenomenon known as coronal rain.
Coronal rain occurs when hot plasma in the eruption cools and condenses then follows the outline of the normally invisible magnetic fields as it rains back to the Sun's chromosphere. I found that particularly amazing to see.
The images were gathered on July 19, 2012 by the Solar Dynamics Observatory’s AIA instrument. One frame was shot every 12 seconds over a span of 21.5 hours from 12:30 a.m. EDT to 10:00 p.m. EDT. The video plays at a rate of 30 frames per second, so each second equals 6 minutes of real time.
What's extra cool is when the scale of this thing is compared to the size of Earth. If you were feeling small earlier today, you should be feeling microscopic after watching this.
Courtesy NASA/JPLLast week could have been called "Chicken Little Week" with the near miss of Earth by an asteroid and and the dazzling, but havoc-producing meteor crossing through the Russian skies. Have you taken off your safety helmet yet?
While it takes an extraordinary week like that to make most of us think about the dangers looming out in space, there are researchers dedicated to tracking the dangerous projectiles in space. Here's a great report on public and private research groups keeping track of the random traffic in the skies.
Interestingly, they claim that we only really spot about 10 percent of the miscellaneous space stuff that could collide with Earth. And, they're not just settling for trying to pinpoint where the problems are. They're trying to figure out ways to deflect or break-up potentially damaging space threats. Taking it one step higher, some are even investigating ways to mine key minerals from these threats to Earth.
Courtesy NISE NetworkWhen things get really really small (nanoscale small), they behave completely differently! For example, gold at the nanoscale can look purple, orange, or red; static electricity has a greater effect on nanoparticles than gravity; and aluminum (the stuff your benign soda cans are made of) is explosive at the nanoscale!
If you want to experience some of these nanoscale phenomena first-hand, check out whatisnano.org, or download the DIY Nano app. The website and the app were both created by the Nanoscale Informal Science Education Network (NISE Net for short), and have videos and activity guides, complete with instructions and material lists, so you can do some nano experiments at home! The app was a Parents' Choice award winner for 2012, and was featured in Wired Magazine's review of apps. Definitely worth a look!
Have fun exploring nanoscale properties!
Courtesy NASAWe like to think of our home planet – Earth – as a pretty unique place. It's the only planet in our solar system capable of sustaining life. We look through telescopes and to see exotic looking planets of various sizes and shapes. But we're the one and only Earth, right?
A new census of planets in the Milky Way galaxy shakes up that thinking. New data collected by NASA's Kepler spacecraft pegs one in six stars in the Milky Way of having planets that are the same size as Earth. That one-sixth fraction translates into an estimate of about 17 billion planets that are the same approximate size as our home.
So we're not as exclusive as might like to think. But the exclusivity meters edges back toward us when you factor in the Goldilocks zone – a distance from the host star that's not too hot nor too cold to sustain life. So far, extended research on the new-found planets has identified only four Earth-sized planets that could possibly reside in a Goldilocks zone. The Kepler project has identified a total of 2,740 potential new planets with more research ongoing.
Courtesy GLOBE at Night(This post is a copy and paste of an email I received for this interesting citizen scientist activity...)
What would it be like without stars at night? What is it we lose? Starry night skies have given us poetry, art, music and the wonder to explore. A bright night sky (aka light pollution) affects energy consumption, health and wildlife too. Spend a few minutes to help scientists by measuring the brightness of your night sky. Join the GLOBE at Night citizen-science campaign. There are 5 GLOBE at Night campaigns in 2013: January 3 - 12, January 31 - February 9, March 3 - 12, March 31 - April 9, and April 29 - May 8. Make a difference and join the GLOBE at Night campaign.
GLOBE at Night is a worldwide, hands-on science and education program to encourage citizen-scientists worldwide to record the brightness of their night sky. During five select sets of dates in 2013, children and adults match the appearance of a constellation (Orion or Leo in the northern hemisphere, and Orion and Crux in the southern hemisphere) with seven star charts of progressively fainter stars. Participants then submit their choice of star chart with their date, time and location. This can be done by computer (after the measurement) or by smart phone or pad (during the measurement). From these data an interactive map of all worldwide observations is created. Over the past 7 years of 10-day campaigns, people in 115 countries have contributed over 83,000 measurements, making GLOBE at Night the most successful, light pollution citizen-science campaign to date. The GLOBE at Night website is easy to use, comprehensive, and holds an abundance of background information. Through GLOBE at Night, students, teachers, parents and community members are amassing a data set from which they can explore the nature of light pollution locally and across the globe.
Listen to a fun skit on GLOBE at Night in a 7-minute audio podcast here.
Courtesy NASA Ames/Chris McKay Scientists working at the bottom of the world have discovered a hardy strain of bacteria living comfortably in a salty lake buried under 20 meters of ice in East Antartica.
The body of water, called Lake Vida, is nearly 3000 years old and might as well be situated on one of Jupiter’s moons. It’s by no means a vacation destination. Sunlight no longer reaches it. The bacteria living in it survive in a pitch-black environment, with sub-freezing temperatures, and in waters that contain seven times the amount of salt found in seawater,
"Lake Vida is a model of what happens when you try to freeze a lake solid, and this is the same fate that any lakes on Mars would have gone through as the planet turned colder from a watery past," says co-leader Peter Doran of the University of Illinois, Chicago. Scientists from NASA, the Desert Research Institute in Reno, and several other institutions make up the expedition team.
The microorganisms belong to a species new to science. They thrive in a briny mix rich in hydrogen, nitrous oxide, and carbon - not exactly your normal chemical stew for gracious living – but somehow the bacteria manage to extract energy from the concoction. The researchers think the high salt content interacting with minerals in lake sediments may be responsible for the unusual chemistry.
The discovery of life in Lake Vida could help in our search for life on other planets or beneath the surfaces of their icy moons.
"This system is probably the best analog we have for possible ecosystems in the subsurface waters of Saturn's moon Enceladus and Jupiter's moon Europa," said Chris McKay, of NASA’s Ames Research Center, and co-author of the paper published online recently in the Proceedings of the National Academy of Sciences Early Edition.
Other subsurface lakes in Antarctica are also under investigation, Lake Vostok, which I posted about previously, and Lake Ellsworth in West Antarctica. Both lakes are millions of years older, and buried under kilometers of ice rather than just meters. It will be interesting to see if some form of life can manage to survive in those even more extreme conditions.
Courtesy National ArchivesSomeone contact Mulder and Scully. Recently declassified documents show that the US Air Force was actually working on building flying saucers in the 1950s. Known as Project 1794, the four digitized documents available on the National Archives website, indicate the program involved development of a disk-shaped aircraft capable of achieving air speeds between Mach 3 and Mach 4 (2,300-3,000 mph) and a height of 100,000 feet! Propulsion was based on the Coandă effect, created by high-speed rotation of the saucer's outer rim. Jet turbines supplied the power. Avro Canada, a Canadian aircraft manufacturer, was also in on this very secret project. The truth might out there, but we might have to wait until the remainder of the two full boxes of documents is digitized and posted online.