Astrobiologists have found that chemical reactions between iron-containing minerals and water might produce hydrogen “food” in the pores and cracks of subsurface rocks, and under temperatures in which microorganisms can survive.
Scientists have previously studied how rock-water reactions produce hydrogen gas in environments too hot for microorganisms, such as below hydrothermal vents on the ocean floor. The hydrogen from these systems mixes with seawater and microorganisms are able to use it when it reaches cooler pockets.
The new study shows that rock-water interactions might also produce hydrogen in cooler environments, which are more abundant on Earth below the seafloor and in some areas of the continents. In these environments, microbial communities could be able to access the resource directly.
There is a large volume of rock on Earth where these low temperature reactions might occur, meaning that a huge subsurface microbial habitat may exist beneath our feet. Similar rocks could also be present on the red planet, and the findings raise questions about whether or not hydrogen-dependent life might have gained a foothold in subsurface environments on ancient Mars.
The paper, “Hydrogen generation from low-temperature water–rock reactions” was published in Nature Geoscience under lead author Lisa Mayhew, research associate at the University of Colorado at Boulder. Mayhew was also an NAIscholar and participant in the 2009 Astrobiology Summer School.
Source: University of Colorado at Boulder