Coupled LTA - PAS FTIR Approach for Studies of Organic Matter Dynamics and Function at the Interface of Soil Aggregates

LTA-PAS FTIR approach can be considered as an original tool useful to study the dynamics, function and protection of soil organic matter (SOM). Studies on SOM are generally carried out mainly using chemical extraction methods that modify both organic substances and mineral phases resulting in possible artifact. Low-Temperature Ashing (LTA) by oxygen plasma allows a controlled removal at low temperature of SOM from the mineral matrix of soil aggregates with minimal disturbance and damage to the inorganic constituents. Photoacoustic (PAS) -FTIR spectroscopy allows to obtain IR spectra from the surface of irregular tri-dimensional specimens. When LTA is coupled with PAS-FTIR spectroscopy, it is possible, at each step, to obtain spectroscopic evidences of the residual OM layers and, by difference, the spectra of the removed SOM. Therefore, the coupled LTA-PAS-FTIR approach can provide insights on the nature of SOM as well as the surface interaction of Organic substances in undisturbed soil aggregates or in other solid materials.