In situ Mössbauer spectroscopy: Evidence for green rust (fougerite) in a gleysol and its mineralogical transformations with time and depth

Abstract A miniaturized Mossbauer spectrometer, adapted to the Earth’s conditions from the instrument developed for Mars space missions, has been used for the first time to study in situ variations with depth and transformations with time of iron minerals in a gleysol. The instrument is set into a PVC tube and can be moved up and down precisely (±1 mm) at the desired depth. Mossbauer spectra were obtained from 15 to 106 cm depth and repeated exactly at the same point at different times to follow mineralogical transformations with time. X-ray diffraction (XRD) and selective extraction techniques were performed on soil samples. The piezometric level of the water table was measured and the com…