Spontaneous Oxygen Isotope Exchange between Carbon Dioxide and Oxygen-Containing Minerals: Do the Minerals “Breathe” CO2?

Abstract

Spontaneous isotopic exchange of oxygen atoms between dry powdered Ti16O 2 oxygen containing minerals and gaseous C18O 2 was studied using gas phase high-resolution Fourier transform infrared absorption spectroscopy of carbon dioxide isotopologues. The absorption rovibrational spectra of all the measured carbon dioxide isotopologues were assigned and used for the quantification of the time-dependent isotope exchange between oxygen atoms (16O) from the crystalline lattice of the solid mineral samples and (18O) oxygen atoms from gaseous C18O 2 . Similarly to our previous studies devoted to isotopic exchange activity of titanium dioxide, we found out that rutile, montmorillonite, siderite, calcite or basaltic minerals also exhibit unexpectedly significant oxygen mobility between solid and gas phases. The rate of formation of gaseous C16O 2 is found to be highly dependent on the nature of the mineral sample. Our previous studies together with the results here presented suggest that such crystal lattice oxygen isotopes mobility can be explained by two mechanisms: cluster-like structure of finely powdered materials or the existence of oxygen deficiency sites in the structure of the crystal lattice.