Molecular fingerprint of soil organic matter as an indicator of pedogenesis processes in Technosols

Purpose Technosol management is one of the greatest challenges for the future, more specifically as regards supporting and/or restoring ecosystems. The understanding of natural soil organic matter (SOM) dynamic from Technosol may give important information about soil functioning and Technosol evolution. Materials and methods According to this, SOM from three French old mine Technosols, (an old tin mine, a lead and zinc, and a gold one which is arsenic-rich), were studied and characterized using thermochemolysis coupled with gas chromatography and mass spectrometry (GC-MS) with tetramethyl ammonium hydroxide (TMAH) as reagent and FTIR. The characterization and quantification of some specific biomacromolecules, used as biomarkers, indicate the specific level of incorporation relative to various subgroups. Global parameters of soils (pH, total organic matter, cation exchange capacity…) were also evaluated. Results and discussion Results on bulk samples show that lipids are the most reactive group and therefore play the most important role in young soil pedogenesis. All of the results show that the behavior of SOM of the Technosol is similar to homolog non-anthropized soil and depends on vegetation type. Conclusions A slight inhibition of bacterial activity is observed which underlines a protective effect of Technosols on SOM degradation due to the low pH, the high clay content, and the presence of Al 3+ and metal(loid)s. In fine, lipid fraction of SOM may act as a well-done fingerprint of pedogenesis processes in Technosols.