Abiotic nitrous oxide production from sediments and brine of Don Juan Pond, Wright Valley Antarctica, at Mars analog temperatures (–40°C)

• Main Authors: Schutte, Charles A., Samarkin, Vladimir A., Peters, Brian, Madigan, Michael T., Casciotti, Karen L., Joye, Samantha B.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Code Ocean 2022
• Subjects: Capsule; Earth Sciences; Antarctica; Mars; extreme environment; exobiology; nitrous oxide; biosignatures; Don Juan Pond; Wright Valley; Antarc*
• Online Access: https://dx.doi.org/10.24433/co.6151632.v1; https://codeocean.com/capsule/2266873/tree/v1

The presence of biogenic gases such as oxygen, methane, and nitrous oxide (N2O) in the atmospheres of extraterrestrial bodies have been postulated as biosignatures of life. Abiotic N2O production was recently documented in Don Juan Pond, Antarctica, a cold, hypersaline Mars analog environment. Here we quantify the temperature-driven kinetics of abiotic N2O production and combine this with stable isotope labeling to demonstrate that N2O is produced from Don Juan Pond sediment and brine at Mars-analog temperatures down to at least –40°C. Further, we show that at any given temperature, N2O production is controlled by the availability of reduced Fe-bearing minerals rather than nitrate. We conclude that abiotic N2O production is possible on Mars and other extraterrestrial bodies and exoplanets; thus, the presence of atmospheric N2O on these bodies should not be taken by itself as an indicator of microbial life.