Aeolian driven silicate comminution unlikely to be responsible for the rapid loss of martian methane

Seasonally varying levels of methane have been measured at parts per billion by volume levels in the lower Martian atmosphere. The source of this methane is not understood, but equally intriguing is its rapid loss, which is higher than the current chemical or photochemical decomposition models suggest. This implies an unknown but efficient sink mechanism. Earlier investigations reported the formation of Si center dot & nbsp; during the comminution of borosilicate glass and quartz that permitted the uptake of methane. This led to the speculation that an analogous aeolian driven comminution of Si-rich minerals on Mars could similarly sequestrate atmospheric methane. However, borosilicate glass is an artificial material and crystalline quartz is not common on the surface of Mars. To investigate whether this mechanism could take place on materials that were more representative of those on Mars, we comminuted a set of Mars analogue silicate rocks/minerals (basalt, obsidian, feldspar, pyroxene, zeolite, opal) in the presence of C-13-labeled methane. Solid-state Nuclear Magnetic Resonance (NMR) analysis of borosilicate glass and quartz indicated silicon carbide bond formation and this observation was supported by attenuated total reflectance-Fourier transform infra-red spectroscopy and X-ray photoelectron spectroscopy. However, silicon carbide bonds and methane sequestration were not detected in our set of Mars analogue samples. We hypothesise that electron donation by redox-active elements within the analogue materials, such as Fe, may have suppressed Si-methyl bond formation during comminution. Aeolian driven Si radical formation appears unlikely to be responsible for the rapid loss of methane in the Martian atmosphere, and thus the methane sink mechanism(s) require further investigation.