资源环境科技发展态势分析平台

Due to the scarcity of O-2 in the modern Martian atmosphere, Mars has been assumed to be incapable of producing environments with sufficiently large concentrations of O-2 to support aerobic respiration. Here, we present a thermodynamic framework for the solubility of O-2 in brines under Martian near-surface conditions. We find that modern Mars can support liquid environments with dissolved O-2 values ranging from -2.5 x10(-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 O-2 entry into brines. General circulation model simulations show that O-2 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 O-2 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 O-2 independent of photosynthesis.