TITLE:
Evaluation of a Toposequence of Soils Derived from Basalt by Fourier Transform Infrared Spectroscopy
AUTHORS:
Wilson Sacchi Peternella, Antônio Carlos Saraiva da Costa
KEYWORDS:
Soil Toposequence, Organic Matter, Clay Minerals and FTIR
JOURNAL NAME:
Open Access Library Journal,
Vol.8 No.9,
September
9,
2021
ABSTRACT: The interaction of organic matter (OM) and clay minerals has been studied as one of the main OM stabilization mechanisms present in different soil classes. The composition of OM present in the soil in terms of humic and fulvic acids and other organic compounds, together with the surface functional groups of different minerals of the clay fraction, such as iron and aluminum oxide and hydroxides type minerals, affect the intensity of the substrate/MO ratio, thus being able to change even the size of the crystals present in the clay mineral fraction. However, this effect is little evaluated due to the limitations in phase separation between OM and the mineralogical fraction of each soil. Therefore, the dissolution of iron oxides was conducted from the clay fraction with sodium dithionite-citrate-bicarbonate (DCB) for better evaluation of the silicate minerals in the soil. The nature of the functional groups of minerals from the clay fraction was evaluated by FTIR spectroscopy and compared with international standard kaolinite and montmorillonite; also evaluated using the technique of area ratio of the main absorption bands of soils derived from basalt and belonging to the toposequence. The results showed that FTIR spectroscopy analysis is a promising tool in the identification of clay minerals such as gibbsite, kaolinite and smectites, observing the due processes of separation of the fractions of interest.