Revista Brasileira de Ciência do Solo | |
Chemical characterization and infrared spectroscopy of soil organic matter from two southern brazilian soils | |
D. P. Dick2  J. H. Z. Santos2  E. M. Ferranti1  | |
[1] ,Universidade Federal do Rio Grande do Sul - UFRGS Instituto de Química Porto Alegre RS | |
关键词: hydrophobicity; organo-mineral interactions; HF-treatment; humic substances; hidrofobicidade; interação organo-mineral; tratamento com HF; substâncias húmicas; | |
DOI : 10.1590/S0100-06832003000100004 | |
来源: SciELO | |
【 摘 要 】
Soil organic matter from the surface horizon of two Brazilian soils (a Latosol and a Chernosol), in bulk samples (in situ SOM) and in HF-treated samples (SOM), was characterized by elemental analyses, diffuse reflectance (DRIFT) and transmission Fourier transform infrared spectroscopy (T-FTIR). Humic acids (HA), fulvic acids (FA) and humin (HU) isolated from the SOM were characterized additionally by ultraviolet-visible spectroscopy (UV-VIS). After sample oxidation and alkaline treatment, the DRIFT technique proved to be more informative for the detection of "in situ SOM" and of residual organic matter than T-FTIR. The higher hydrophobicity index (HI) and H/C ratio obtained in the Chernosol samples indicate a stronger aliphatic character of the organic matter in this soil than the Latosol. In the latter, a pronounced HI decrease was observed after the removal of humic substances (HS). The weaker aliphatic character, the higher O/C ratio, and the T-FTIR spectrum obtained for the HU fraction in the Latosol suggest the occurrence of surface coordination of carboxylate ions. The Chernosol HU fraction was also oxygenated to a relatively high extent, but presented a stronger hydrophobic character in comparison with the Latosol HU. These differences in the chemical and functional group composition suggest a higher organic matter protection in the Latosol. After the HF treatment, decreases in the FA proportion and the A350/A550 ratio were observed. A possible loss of FA and condensation of organic molecules due to the highly acid medium should not be neglected.
【 授权许可】
CC BY
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