The Saltiest Body of Water on Earth

A Pond in Antarctica that Never Freezes!

In so many ways, Don Juan Pond in the Dry Valleys of Antarctica is one of the most unearthly places on the planet. An ankle-deep mirror between mountain peaks and rubbled moraine, the pond is an astonishing 18 times saltier than the Earth’s oceans and virtually never freezes, even in temperatures of more than 40 degrees below zero Fahrenheit (-40 C).

A Model for Brine Pools on Other Planets?

Now, a research team led by biogeochemists from the University of Georgia has discovered at the site a previously unreported chemical mechanism for the production of nitrous oxide, an important greenhouse gas. Possibly even more important, the discovery could help space scientists understand the meaning of similar brine pools in a place whose ecosystem most closely resembles that of Don Juan Pond: Mars.

The research, published April 25, 2010 in the journal Nature Geoscience, adds an intriguing new variable to growing evidence that there has been—and may still be—liquid water on Mars, a usual prerequisite for the formation of life. In fact, the new findings could help space scientists develop sensors for detecting such brines on Mars—thus narrowing the search for places where life may exist.

Assessing Microbial Activity in Extreme Environments

“The pond’s soils and brines and the surrounding rock types are similar to those found on Mars,” said Samantha Joye, a faculty member in the department of marine sciences in the Franklin College of Arts and Sciences and lead author on the paper. “So it provides an ideal location to assess microbial activity in extreme environments. While we did not detect any ‘bio-gases’ such as hydrogen sulfide and methane, we did, surprisingly, measure high concentrations of nitrous oxide, which is normally an indicator of microbial activity. We needed to find out whether a non-organic process could account for this nitrous oxide production.”

The Saltiest Body of Water on Earth

The pond, which is a roughly 1,000- by 400-meter basin, is the saltiest body of water on Earth by far, some eight times saltier than the Dead Sea. While researchers more than 30 years ago reported finding abundant and varied microflora of fungi, bacteria, blue-green algae and yeasts, since then and during the Joye team’s work, such life has been non-existent. Since the depth level and area covered by the pond (which is fed by hypersaline groundwater) have demonstrably varied over the years, this wasn’t unexpected. What did surprise the team was that even with no life-forms present, they were able to measure nitrous oxide, perhaps best known to most people as the “laughing gas” used in dental procedures. (The amounts measured in the air were beneath a level that could make a person light-headed or giddy, as “laughing gas” can.)

Products of the Extreme Brine Environment

“What we found was a suite of brine-rock reactions that generates a variety of products, including nitrous oxide and hydrogen,” said Joye. “In addition to Don Juan Pond, this novel mechanism may occur in other environments on Earth as well and could serve as both an important component of the Martian nitrogen cycle and a source of fuel [hydrogen] to support microbial chemosynthesis.”

Even more interesting, perhaps, is that the results suggest that an additional mechanism — the reaction of brine-derived nitrates with basaltic rock — could be a “previously unrecognized means for mobilizing nitrate from the surface soils . . . and returning it to the Martian atmosphere as nitrous oxide,” Joye said.

Protecting the Unique Environment

Beauty aside, though, the team had to dress in sterile suits and masks and use sterile instruments for sampling to avoid possible contamination. They also collected the minimal amount of material necessary to achieve their research goals.

The discovery of the new mechanism opens numerous questions that must be studied, including the possibility that the process is taking place in other extreme Antarctic habitats or that it might contribute to nitrous oxide in temperate soils—a possible new clue to understanding greenhouse gases involved in global warming.

The most crucial result, however, may be in understanding how similar brine pools on Mars might work and whether they could support life.

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Fonte:www.geology.com

Hunt For Weird Life Forms

Russians will be first to explote Untouched Antartic lake Vostok, in hunt for Weird life forms.

The lake has been isolated and buried for 14 million years!

Lake Vostok, Antarctica The area around Lake Vostok is circled in red. NASA

An oxygen-rich lake, unreachable for the past 14 million years and buried beneath a thick sheet of ice, is about to be penetrated by a drill vit from a faraway place. It’s possible that special life forms have adapted to live in this extreme environment, and scientists hope to learn more once they can analyze water samples.

No, sorry, it’s not on Europa — it’s in Antarctica. But the environment of Lake Vostok, which Russian scientists are about to drill open, is very similar to that Jovian moon and to Enceladus, a frozen satellite of Saturn. Astrobiologists are among those eager to uncover Lake Vostok’s Miocene-era secrets.

The Antarctic Treaty Secretariat, a body set up to protect the frozen continent, approved a Russian team’s process to extract water from the lake while preventing contamination, according to New Scientist. By the end of this month, a team from Russia's Arctic and Antarctic Research Institute (AARI) in St Petersburg expects to hit water.

The lake’s water pressure will push the drilling fluid up into the borehole, where it will freeze. Next year, researchers will return to extract that ancient water and analyze its contents.

Efforts to drill into Lake Vostok have been stalled since 1998, when the treaty organization stopped the Russian team’s work until further environmental studies could prove the lake would not be polluted. Later studies showed this would be tricky — in 2003, NASA astrobiologists said the lake’s high nitrogen and oxygen levels would cause the water to fizz like a shaden soda can, opening the lake to possible contamination and even posing a threat to the scientists.

Lake Vostok has oxygen levels 50 times that of other freshwater lakes, so scientists believe life would have had to evolve protective enzymes or other adaptations to survive. If so, these extremophiles could have implications for life on Enceladus or Europa.

No one is sure where the ice-water boundary lies, so scientists are not sure when they’ll break through.

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Fonte: Geology.com