Nitrogen fixation on early Mars and other terrestrial planets: Experimental demonstration of abiotic fixation reactions to nitrite and nitrate

作者：Summers David P^*; Khare Bishun

来源：Astrobiology, 2007, 7(2): 333-341.

DOI：10.1089/ast.2006.0032

• nitrogen fixation
• early Mars
• early Earth
• terrestrial planets
• abiotic nitrogen fixation
• prebiotic chemistry
• early atmospheres
• planetary habitability
• nitrate
• nitrite
• nitric oxide
• nitrous oxide
• nitrogen dioxide
• nitric acid
• nitrogen
• carbon dioxide
• photochemistry

Understanding the abiotic fixation of nitrogen is critical to understanding planetary evolution and the potential origin of life on terrestrial planets. Nitrogen, an essential biochemical element, is certainly necessary for life as we know it to arise. The loss of atmospheric nitrogen can result in an incapacity to sustain liquid water and impact planetary habitability and hydrological processes that shape the surface. However, our current understanding of how such fixation may occur is almost entirely theoretical. This work experimentally examines the chemistry, in both gas and aqueous phases, that would occur from the formation of NO and CO by the shock heating of a model carbon dioxide/nitrogen atmosphere such as is currently thought to exist on early terrestrial planets. The results show that two pathways exist for the abiotic fixation of nitrogen from the atmosphere into the crust: one via HNO and another via NO2. Fixation via HNO, which requires liquid water, could represent fixation on a planet with liquid water (and hence would also be a source of nitrogen for the origin of life). The pathway via NO2 does not require liquid water and shows that fixation could occur even when liquid water has been lost from a planet's surface (for example, continuing to remove nitrogen through NO2 reaction with ice, adsorbed water, etc.).

• 出版日期2007-4