"The secret appears to lie in how temperature and pressure affect the reactivity of organic compounds, and, maybe more importantly, how the properties of water change deep in sediments and sedimentary rocks," says Shock. "The transformation in how water behaves is so enormous that we would hardly recognize it as the same stuff that comes out of our kitchen taps."
Most organic reactions at the Earth's surface do not work very well in water; either they need an organism that has evolved the mechanisms to promote organic reactions in water or they need an organic solvent, hexane or benzene, for example. The very deep Earth, below where microbial life has been shown to exist, has lots of rocks but no organic solvents. It does, however, have very hot water.
Hilairy Hartnett, an assistant professor in the School of Earth and Space Exploration and ASU's Department of Chemistry and Biochemistry, is part of Shock's interdisciplinary group examining the mechanisms of the sub-surface carbon cycle. The team hypothesizes that conditions deep in the Earth might be good for complex organic reactions.
"Evidence suggests that hot water at high pressures - conditions we'd find in the subsurface - is actually a very good solvent for organic reactions," Hartnett says. "It might be possible for these reactions to occur without biology if the conditions are right." She explains, "Biological processes can promote reactions to generate complex organic molecules even at unfavorable low temperatures and pressures - the difference for the deep Earth is the high-temperature and pressure."
Spurred by a $1.5M grant from the National Science Foundation, the team will apply new theoretical models of how water at high temperatures
|Contact: Nikki Staab|
Arizona State University