Banca de DEFESA: OCTÁVIO VIORATTI TELLES DE MOURA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : OCTÁVIO VIORATTI TELLES DE MOURA
DATA : 19/02/2020
HORA: 09:00
LOCAL: Departamento de Solos-Sala 24
TÍTULO:

STRUCTURE OF SOIL ORGANIC MATTER IN A CAMBISOL AND A CHERNOSOL FROM THE STATE OF RIO DE JANEIRO-BRAZIL

PALAVRAS-CHAVES:

Humic substances. Spectroscopy. Organo-mineral interactions. 

PÁGINAS: 90
GRANDE ÁREA: Ciências Agrárias
ÁREA: Agronomia
SUBÁREA: Ciência do Solo
ESPECIALIDADE: Química do Solo
RESUMO:

The humification process of soil organic matter (SOM) is possibly one of the research themes of major controversies in soil sciences. Especially in tropical soils, where humic substances (SH) regulate most phenomena, the organic carbon stock and incorporation is highly dependent on its structural quality. Mechanisms of carbon stabilization occur to a great extent through the organo-mineral interactions between the molecules that are deposited and the mineralogy or texture present in soil. Understanding and explaining the organo mineral interactions in the soil allows the understanding of the HS formation in soil and therefore, the process humification. The present work aimed to structurally characterize the MOS, specifically the fraction of HA formed in soils with different texture and different degree of pedogenetic evolution (Cambisol and Chernosol), applying spectroscopic techniques combined with chemometric data analysis. For this, humic acids (HA) were extracted from a Cambisol and a Chernosol from the state of Rio de Janeiro. The HA were then characterized using spectroscopic techniques (UV-vis, ATR-FTIR and ¹³C NMR CP / MAS). Chemometric analyzes were applied to spectral data such as: PCA-UV / vis; PCA-ATR / FTIR and PCA-¹³C NMR CP / MAS, descriptive analysis, test of means and multivariate curve resolution -MCR. The results show that the HA extracted from Cambisol and Chernosol are structurally different. HA from have a lower E₄/E₆ ratio than Chernosolo. The functional groups obtained by ATR-FTIR show that the predominance of the -CH groups belonging to -CH₂ and -CH₃ and hydroxyls (-OH) while those in HA from Chernosol, those with predominate of aromatic C=C groups. Cambisol HA are mainly composed of C_Aquil-H,R (32%) and -C=O (6.36%) structures, while HA extracted from Chernossolo have a higher amount of C_Alkyl, N,O (12%), C_Alkyl-O (13%) and C_Aromatico-H,R (18%). These characteristics generate aliphatic and more hydrophobic properties in HA from Cambisol than those present in the HA from Chernossolo. The mechanisms for stabilizing organic carbon in Cambisol occur through hydrophobic interactions, whereas the presence of clays in the Chernossol, including 2: 1, provides other interaction sites that enable the stabilization of protein compounds. The richness of SOMS structures in the Chernosol can provide nutritional conditions for the presence of a greater amount of microorganism and, as a consequence, a greater number of nematodes. The structural characterization of the HA combined with aquimiometrics is a methodology that allows to study the process of humification in soils.

MEMBROS DA BANCA:
Presidente - 1399485 - ANDRES CALDERIN GARCIA
Interno - 1060711 - MARCOS GERVASIO PEREIRA
Externo à Instituição - ADEMIR FONTANA