The importance of humin in soil characterisation: A study on Amazonian soils using different fluorescence techniques

Author(s)

Tadini, Amanda Maria ^{[1, 2]} ; Nicolodelli, Gustavo ^[2] ; Mounier, Stephane ^[3] ; Montes, Celia Regina ^{[4, 5]} ; Bastos Pereira Milori, Debora Marcondes ^[2]

Affiliation

^[1] Univ Sao Paulo, Inst Chem Sao Carlos, Sao Carlos, SP - Brazil

^[2] EMBRAPA Agr Instrumentat, Sao Carlos, SP - Brazil

^[3] Univ Toulon & Var, Lab PROTEE, EA3819, F-83041 Toulon 9 - France

^[4] Univ Sao Paulo, Ctr Energia Nucl Agr, Piracicaba, SP - Brazil

^[5] Univ Sao Paulo, NUPEGEL, Piracicaba, SP - Brazil

• Document type: Journal article
• Source: Science of The Total Environment; v. 537, p. 152-158, DEC 15 2015.
• Web of Science Citations: 10

Abstract

Soil organic matter (SOM) is a complex mixture of molecules with different physicochemical properties, with humic substances (HS) being the main component as it represents around 20-50% of SOM structure. Soil of the Amazon region is considered one of the larger carbon pools of the world; thus, studies of the humic fractions are important for understanding the dynamics of organic matter (OM) in these soils. The aim of this study was to use laser-induced fluorescence spectroscopy (LIFS) and a combination of excitation-emission matrix (EEM) fluorescence with Parallel Factor Analysis (CP/PARAFAC) to assess the characteristics of humin (HU) extracted from Amazonian soils. The results obtained using LIFS showed that there was an increasing gradient of humification degree with depth, the deeper horizon presenting a higher amount of aromatic groups in the structure of HU. From the EEM, the contribution of two fluorophores with similar behaviour in the structures of HU and whole soil was assessed. Additionally, the results showed that the HU fraction might represent a larger fraction of SOM than previously thought: about 80-93% of some Amazon soils. Therefore, HU is an important humic fraction, thus indicating its role in environmental analysis, mainly in soil analysis. (C) 2015 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 11/03250-2 - Quantification and dynamics of carbon associated with deep spodic horizons of Amazon Forest soils, towards possible climatic changed
• Grantee: Célia Regina Montes
• Support Opportunities: Regular Research Grants
• FAPESP's process: 13/13013-3 - Characterization Humic Substances extracted from Amazonian Soils
• Grantee: Amanda Maria Tadini
• Support Opportunities: Scholarships in Brazil - Doctorate