Sea-Ice Brinicles As Spires of Life
BBC (2011) Chadden Hunter
A brinicle grows from the ice sheet above in McMurdo Sound, Antarctica. Over the course of 12 hours, it descends to the seafloor below, then extends another 20 feet along the sea bed, trapping anything it touches in ice. Most creatures here move far too slowly to escape its path of death.
Spring's not all about pretty flowers and greening trees. For some scientists it means watching Arctic ice. Scientists and engineers with NASA's Operation IceBridge are already at it, surveying glaciers in Greenland, Alaska and northern Canada. The flight part of the largest aerial survey of Earth's polar ice ever flown – a six-year mission over both poles aimed at producing a three-dimensional view of Arctic and Antarctic ice sheets, ice shelves and their sea ice.
Here, NASA's P-3B sits on the tarmac of the Kangerlussuaq Airport. The plane is equipped with a suite of instruments that gather data as the plane flies over the ice. It also carries scientists and teachers, some of whom took the following images.
The glacial Alaskan mountains are seen from high altitude aboard the P-3B during the IceBridge flight from Thule, Greenland, to Fairbanks, Alaska, on March 21, 2013.
A true river of ice, or glacier, on Greenland's Geikie Peninsula.
Tongue-shaped moraines appear to lick at the Penny Ice Cap on Baffin Island, Nunavut, Canada. These moraines are debris that was plowed up and left behind by past glaciers
Another moraine left by a small glacier on Penny Ice Cap on Baffin Island, Nunavut, Canada.
This year's aerial survey of the Penny Ice Cap glacier follows previous radar surveys done in 1995, 2000 and 2005 using the Airborne Topographic Mapper and CReSIS radar instrument.
Near Thule Air Base, sled dogs rest on the sea ice in North Star Bay. Behind them is the 700-foot-high Mount Dundas. Cities in Greenland are connected by ship and air, but shorter distances are crossed by snowmobile or dogsleds.
No, not another glacier, but an ice-covered fjord on Baffin Island near Davis Strait, which is in the distance. Baffin Island is the fifth largest island in the world.
This is a mosaic image of sea ice in the Beaufort Sea. The darkest zone is open water. Light blue zones are thick sea ice, while dark blue zones are thinner ice. The image was created by the Digital Mapping System (DMS) instrument aboard the IceBridge P-3B.
Icebergs crowd the sea ice of Jakobshavn Fjord, seen from NASA’s P-3B aircraft on the Apr. 4, 2013, IceBridge survey. Jakobshavn Glacier produces one in ten Greenland icebergs and is one of the fastest moving ice streams in the world.
NASA / DMS
Another view of the cracked Beaufort Sea ice by the Digital Mapping System (DMS) instrument aboard the IceBridge P-3B. The DMS uses a camera that points down through a window in the underside of the plane. It snaps a frame each second which are combined into a mosaic.
On April 8, 2013, science teacher Mark Buesing of Libertyville High School in Libertyville, Ill., shoots Greenland glaciers through the window of NASA's P-3B.
Eastern Greenland's Helheim Fjord is surveyed on April 5, 2013, from the NASA P-3B. Helheim is one of the largest in Greenland.
The P-3B sees its shadow on April 9, 2013, on the sea ice southeast of Greenland. Flying low altitude is all part of gathering detailed ice data.
Danish high school science teacher Jette Rygaard Poulsen watches the Greenland ice roll by from a window of the P-3B airborne laboratory on Apr. 8, 2013.
Not everything is icy in Greenland. Even as early as April 8, southwestern Greenland has ice free fjords.
An actively calving glacier front on the ocean in southwestern Greenland on April 8.
In two plots of topographic data from the Jakobshavn Glacier warmer colors are higher ice elevation. The calving front is at the transition from warm to cool colors. The difference between the two dates of survey reveal a loss of about 200 meters of ice.
It doesn't affect the ice, but there are some other interesting sights in Greenland this spring, like the aurora borealis over Kangerlussuaq.
What's cooler than being cool? Brine-cold.
When salt-rich water leaks out of sea ice, it sinks into the sea and can occasionally create an eerie finger of ice called a brinicle. New research explains how these strange fingers of ice form and how the salty water within sea ice could have been a prime environment in which life may have evolved.
The study, published in the American Chemical Society's journal Langmuir, suggests that brinicles form in the same way as hydrothermal vents, except in reverse. Hydrothermal vents are spiny-looking towers on the ocean bottom where boiling, chemical-rich water flows out of the seafloor.
The brinicle-forming process goes like this: When sea ice freezes in the Arctic and Antarctic, the salt and other ions in the water is excluded from the water crystals, said study author Bruno Escribano, a researcher at the Basque Center for Applied Mathematics in the Basque Country in northern Spain. This salt-heavy brine accumulates in fractures and compartments within the sea ice.
Inevitably, however, sea ice cracks, and the brine leaks out. The brine itself is colder than the freezing point of seawater, since salt-rich water freezes at lower temperatures (hence the reason people put salt on icy sidewalks in the winter, enabling the ice to remain a liquid when it's below freezing), Escribano told OurAmazingPlanet.
Since the concentration of water in the brine is lower than that in the ocean — and water moves from high to low concentrations, via osmosis — water is attracted to the brine. But the brine is so cold that the water freezes, forming a descending tube of ice, Escribano said.
Hydrothermal vents form by an analogous method: Ion-rich hot water is expelled from the seafloor and then begins to dissolve, forming a porous shell of metal extending upward. Water then rushes in, moving from high to low concentration, rupturing the membrane and causing more metal-rich water to spurt out, extending the tube and repeating the process.
Both are examples of "chemical gardens," a type of chemical process and the name of an experiment common in chemistry sets that operates along the same principles and forms tubes of crystals that make plant-like shapes, Escribano said.
Brine-rich compartments within sea ice have some properties that could have helped life originate, Escribano said. "Inside these compartments inside the ice, you have a high concentration of chemical compounds, and you also have lipids, fats, that coat the inside of the compartment," he said. "These can act as a primitive membrane — one of the conditions necessary for life." They also contain a mixture of acidic and basic components that could provide energy necessary to form more complex molecules, perhaps even DNA, he said.
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