Article | Published:

O2 solubility in Martian near-surface environments and implications for aerobic life

Nature Geosciencevolume 11pages905909 (2018) | Download Citation


Due to the scarcity of O2 in the modern Martian atmosphere, Mars has been assumed to be incapable of producing environments with sufficiently large concentrations of O2 to support aerobic respiration. Here, we present a thermodynamic framework for the solubility of O2 in brines under Martian near-surface conditions. We find that modern Mars can support liquid environments with dissolved O2 values ranging from ~2.5 × 10−6 mol m−3 to 2 mol m−3 across the planet, with particularly high concentrations in polar regions because of lower temperatures at higher latitudes promoting O2 entry into brines. General circulation model simulations show that O2 concentrations in near-surface environments vary both spatially and with time—the latter associated with secular changes in obliquity, or axial tilt. Even at the limits of the uncertainties, our findings suggest that there can be near-surface environments on Mars with sufficient O2 available for aerobic microbes to breathe. Our findings may help to explain the formation of highly oxidized phases in Martian rocks observed with Mars rovers, and imply that opportunities for aerobic life may exist on modern Mars and on other planetary bodies with sources of O2 independent of photosynthesis.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Data availability

The generated data output from the climate model used for this study can be made available upon request from the authors.

Additional information

Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.


  1. 1.

    Catling, D. C., Glein, C. R., Zahnle, K. J. & McKay, C. P. Why O2 is required by complex life on habitable planets and the concept of planetary ‘oxygenation time’. Astrobiology 5, 415–438 (2005).

  2. 2.

    Fischer, W. W., Hemp, J. & Johnson, J. E. Evolution of oxygenic photosynthesis. Annu. Rev. Earth Planet. Sci. 44, 647–683 (2016).

  3. 3.

    Nair, H., Allen, M., Anbar, A. D., Yung, Y. L. & Clancy, R. T. A photochemical model of the Martian atmosphere. Icarus 111, 124–150 (1994).

  4. 4.

    Mahaffy, P. R. et al. Abundance and isotopic composition of gases in the Martian atmosphere from the Curiosity rover. Science 341, 263–266 (2013).

  5. 5.

    Barker, E. S. Detection of molecular oxygen in the Martian atmosphere. Nature 238, 447–448 (1972).

  6. 6.

    Owen, T. et al. The composition of the atmosphere at the surface of Mars. J. Geophys. Res. 82, 4635–4639 (1977).

  7. 7.

    Hartogh, P. et al. Herschel/HIFI observations of Mars: first detection of O2 at submillimeter wavelength and upper limits on HCl and H2O2. Astron. Astrophys. 521, L49 (2010).

  8. 8.

    Shaheen, R., Niles, P. B., Chong, K., Corrigan, C. M. & Thiemens, M. H. Carbonate formation events in ALH84001 trace the evolution of the Martian atmosphere. Proc. Natl Acad. Sci. USA 112, 336–341 (2015).

  9. 9.

    Lanza, N. L. et al. High manganese concentrations in rocks at Gale crater, Mars. Geophys. Res. Lett. 41, 5755–5763 (2014).

  10. 10.

    Arvidson, R. E. et al. High concentrations of manganese and sulfur in deposits on Murray Ridge, Endeavour crater, Mars. Am. Mineral. 101, 1389–1405 (2016).

  11. 11.

    Hurowitz, J. A. Redox stratification of an ancient lake in Gale crater, Mars. Science 356, eaah6849 (2017).

  12. 12.

    Ojha, L. et al. Spectral evidence for hydrated salts in recurring slope lineae on Mars. Nat. Geosci. 8, 829–832 (2015).

  13. 13.

    Rummel, J. D. et al. A new analysis of Mars ‘Special Regions’: findings of the second MEPAG Special Regions Science Analysis Group (SR-SAG2). Astrobiology 14, 887–968 (2014).

  14. 14.

    Kounaves, S. P. et al. Identification of the perchlorate parent salts at the Phoenix Mars landing site and possible implications. Icarus 232, 226–231 (2014).

  15. 15.

    Leshin, L. A. et al. Volatile, isotope, and organic analysis of Martian fines with the Mars Curiosity rover. Science 341, 1238937 (2013).

  16. 16.

    Toner, J. D., Catling, D. C. & Light, B. The formation of supercooled brines, viscous liquids, and low-temperature perchlorate glasses in aqueous solutions relevant to Mars. Icarus 233, 36–47 (2014).

  17. 17.

    Pestova, O. N., Myund, L. A., Khripun, M. K. & Prigaro, A. V. Polythermal study of the systems M(ClO4)2-H2O (M2+ = Mg2+, Ca2+, Sr2+, Ba2+). Russ. J. Appl. Chem. 78, 409–413 (2005).

  18. 18.

    Marion, G. M., Catling, D. C., Zahnle, K. J. & Claire, M. W. Modeling aqueous perchlorate chemistries with applications to Mars. Icarus 207, 675–685 (2010).

  19. 19.

    Zakem, E. J. & Follows, M. J. A theoretical basis for a nanomolar critical oxygen concentration. Limnol. Oceanogr. 62, 795–805 (2017).

  20. 20.

    Stolper, D. A., Revsbech, N. P. & Canfield, D. E. Aerobic growth at nanomolar oxygen concentrations. Proc. Natl Acad. Sci. USA 107, 18755–18760 (2010).

  21. 21.

    Mills, D. B. et al. Oxygen requirements of the earliest animals. Proc. Natl Acad. Sci. USA 111, 4168–4172 (2014).

  22. 22.

    Laskar, J. et al. Long term evolution and chaotic diffusion of the insolation quantities of Mars. Icarus 170, 343–364 (2004).

  23. 23.

    Richardson, M. I., Toigo, A. D. & Newman, C. E. PlanetWRF: a general purpose, local to global numerical model for planetary atmospheric and climate dynamics. J. Geophys. Res. 112, E09001 (2007).

  24. 24.

    Toigo, A. D., Lee, C., Newman, C. E. & Richardson, M. I. The impact of resolution on the dynamics of the Martian global atmosphere: varying resolution studies with the MarsWRF GCM. Icarus 221, 276–288 (2012).

  25. 25.

    Archer, D. G. & Carter, R. W. Thermodynamic properties of the NaCl + H2O system. 4. Heat capacities of H2O and NaCl(aq) in cold-stable and supercooled states. J. Phys. Chem. B 104, 8563–8584 (2000).

  26. 26.

    Toner, J. D. & Catling, D. C. Water activities of NaClO4, Ca(ClO4)2, and Mg(ClO4)2 brines from experimental heat capacities: water activity >0.6 below 200 K. Geochim. Cosmochim. Acta 181, 164–174 (2016).

  27. 27.

    Clegg, S. L. & Brimblecombe, P. The solubility and activity coefficient of oxygen in salt solutions and brines. Geochim. Cosmochim. Acta 54, 3315–3328 (1990).

  28. 28.

    Konnik, E. I. Salting-out and salting-in of gaseous non-electrolytes in aqueous solutions of electrolytes. Russ. Chem. Rev. 46, 577–588 (1977).

  29. 29.

    Pitzer, K. S. Theoretical considerations of solubility with emphasis on mixed aqueous electrolytes. Pure Appl. Chem. 58, 1599–1610 (1989).

  30. 30.

    Toner, J. D., Catling, D. C. & Light, B. A revised Pitzer model for low-temperature soluble salt assemblages at the Phoenix site, Mars. Geochim. Cosmochim. Acta 166, 327–343 (2015).

  31. 31.

    Silvester, L. F. & Pitzer, K. S. Thermodynamics of electrolytes. X. Enthalpy and the effect of temperature on the activity coefficients. J. Solution Chem. 7, 327–337 (1978).

  32. 32.

    Tromans, D. Modeling oxygen solubility in water and electrolyte solutions. Ind. Eng. Chem. Res. 39, 805–812 (2000).

  33. 33.

    Kasting, J. F., Liu, S. C. & Donahue, T. M. Oxygen levels in the prebiological atmosphere. J. Geophys. Res. 84, 3097–3107 (1979).

  34. 34.

    Pavlov, A. A. & Kasting, J. F. Mass-independent fractionation of sulfur isotopes in Archean sediments: strong evidence for an anoxic Archean atmosphere. Astrobiology 2, 27–41 (2002).

  35. 35.

    Lyons, T. W., Reinhard, C. T. & Planavsky, N. J. The rise of oxygen in Earth’s early ocean and atmosphere. Nature 506, 307–315 (2014).

  36. 36.

    Johnson, J. E., Gerpheide, A., Lamb, M. P. & Fischer, W. W. O2 constraints from Paleoproterozoic detrital pyrite and uraninite. Geol. Soc. Am. Bull. 126, 813–830 (2014).

  37. 37.

    Webster et al. Background levels of methane in Mars’ atmosphere show strong seasonal variations. Science 360, 1093–1096 (2018).

  38. 38.

    Orosei, et al. Radar evidence of subglacial liquid water on Mars. Science 361, 1093–1096 (2018).

  39. 39.

    Grotzinger, J. P. & Milliken, R. E. in Sedimentary Geology of Mars SEPM Special Publication Vol. 102 (eds Grotzinger, J. P. & Milliken, R. E.) 1–48 (Society for Sedimentary Geology, Tulsa, 2012).

  40. 40.

    Tromans, D. Temperature and pressure dependent solubility of oxygen in water: a thermodynamic analysis. Hydrometallurgy 48, 327–342 (1998).

  41. 41.

    Tromans, D. Oxygen solubility modeling in inorganic solutions: concentration, temperature and pressure effects. Hydrometallurgy 50, 279–296 (1998).

  42. 42.

    Toner, J. D., Catling, D. C. & Light, B. A revised Pitzer model for low-temperature soluble salt assemblages at the Phoenix site, Mars. Geochim. Cosmochim. Acta 166, 327–343 (2015).

  43. 43.

    Khomutov, N. E. & Konnik, E. I. Solubility of oxygen in aqueous electrolyte solutions. Russ. J. Phys. Chem. 48, 359–362 (1974).

  44. 44.

    Manion, J. A. et al. NIST Standard Reference Database 17 Version 7.0 Release 1.6.8 (National Institute of Standards and Technology, 2016).

  45. 45.

    Li, D. et al. Phase diagrams and thermochemical modeling of salt lake brine systems. II. NaCl+H2O, KCl+H2O, MgCl2+H2O and CaCl2+H2O systems. Calphad 53, 78–89 (2016).

  46. 46.

    Skamarock, W. C. & Klemp, J. B. A time-split nonhydrostatic atmospheric model for weather research and forecasting applications. J. Comput. Phys. 227, 3465–3485 (2008).

  47. 47.

    Arakawa, A. & Lamb, V. R. Computational design of the basic dynamical processes of the UCLA general circulation model. Methods Comput. Phys. 17, 173–265 (1977).

  48. 48.

    Guo, X., Lawson, W. G., Richardson, M. I. & Toigo, A. Fitting the Viking lander surface pressure cycle with a Mars general circulation model. J. Geophys. Res. 114, E07006 (2009).

  49. 49.

    Christensen, P. R. et al. Mars Global Surveyor Thermal Emission Spectrometer experiment: investigation description and surface science results. J. Geophys. Res. 106, 23823–23871 (2001).

  50. 50.

    Putzig, N. & Mellon, M. Apparent thermal inertia and the surface heterogeneity of Mars. Icarus 191, 68–94 (2007).

  51. 51.

    Mischna, M. A. On the orbital forcing of Martian water and CO2 cycles: a general circulation model study with simplified volatile schemes. J. Geophys. Res. 108, E65062 (2003).

  52. 52.

    Forget, F., Haberle, R. M., Montmessin, F., Levrard, B. & Head, J. W. Formation of glaciers on Mars by atmospheric precipitation at high obliquity. Science 311, 368–371 (2006).

  53. 53.

    Haberle, R. M., Murphy, J. R. & Schaeffer, J. Orbital change experiments with a Mars general circulation model. Icarus 161, 66–89 (2003).

Download references


V.S. would like to dedicate this work in memory of A. S. Kubik who inspired so many to search for life on other worlds and brought so much life to this planet. V.S. thanks the Simons Foundation Collaboration on the Origins of Life for supporting this work (338555). A portion of this work was performed at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. W.W.F. acknowledges support of the David and Lucile Packard Foundation and Simons Foundation Collaboration on the Origins of Life, and L.M.W. the support of a NASA Earth Space and Science Fellowship. Resources supporting this work were provided by the NASA High-End Computing (HEC) Program through the NASA Advanced Supercomputing (NAS) Division at Ames Research Center as well as the High-Performance Computing facilities of the Jet Propulsion Laboratory, Office of the Chief Information Officer.

Author information


  1. Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA

    • Vlada Stamenković
    •  & Michael Mischna
  2. Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA

    • Vlada Stamenković
    • , Lewis M. Ward
    •  & Woodward W. Fischer
  3. Harvard University, Cambridge, MA, USA

    • Lewis M. Ward


  1. Search for Vlada Stamenković in:

  2. Search for Lewis M. Ward in:

  3. Search for Michael Mischna in:

  4. Search for Woodward W. Fischer in:


V.S., L.M.W. and W.W.F. conceptualized this study. M.M. ran the GCM simulations for all obliquities. V.S. developed the solubility model for all brines, extended the idea to a three-dimensional and time-dependent (obliquity-driven) solubility framework, led the writing of the manuscript and prepared all figures and tables. All authors contributed to the writing of the manuscript.

Competing interests

The authors declare no competing interests.

Corresponding author

Correspondence to Vlada Stamenković.

Supplementary information

  1. Supplementary Information

    Supplementary Methods, Supplementary Figures 1–4, Supplementary Tables 1–4.

About this article

Publication history