A new research in Antarctica has shown a non-organic method to produce nitrous oxide, an important greenhouse gas.
A team of scientists, led by biogeochemists from the University of Georgia, made the discovery at Don Juan Pond in the Dry Valleys of Antarctica.
The pond is almost 18 times saltier than the Earth's oceans and virtually never freezes, even in temperatures of more than 40 degrees below zero Fahrenheit.
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 study 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.
Lead author Samantha Joye, a faculty member in the department of marine sciences in the Franklin College of Arts and Sciences, said: "The pond's soils and brines and the surrounding rock types are similar to those found on Mars,"
"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."
Joye went on: "What we found was a suite of brine-rock reactions that generates a variety of products, including nitrous oxide and hydrogen.
"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 stated.
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.
The study has appeared in the journal Nature Geoscience.