Chemical and spectroscopic characterization of Humic acids from a soil toposequence in venezuela
作者:
Carmen Rivero,
Jorge Paolini,
Nicola Senesi,
Valeria DíOrazio,
期刊:
Communications in Soil Science and Plant Analysis
(Taylor Available online 1998)
卷期:
Volume 29,
issue 19-20
页码: 2893-2904
ISSN:0010-3624
年代: 1998
DOI:10.1080/00103629809370163
出版商: Taylor & Francis Group
数据来源: Taylor
摘要:
An investigation was conducted on physico‐chemical properties of humic acids (HAs) in Venezuelan soils. The HAs were extracted by the NaOH method from a Banco‐Bajio‐Estero soil toposequence (local names for soils located at high, intermediate and low topographic levels), in the Venezuelan plains (Mantecal, Apure State). The extracted HAs were analyzed for elemental composition and characterized by fluorescence, Fourier transform infrared (FT‐IR) and electron spin resonance (ESR) spectroscopies. The results showed that free radical concentration of HAs increased from soils at the highest to soils at the lowest topographic position. High carbon (C), nitrogen (N), and carboxyl group contents, E4/E6ratio, aliphatic character and concentration of free radicals, and low oxygen (O) and phenolic hydroxyl group contents and total acidity were typical of HA from soils at the lower relief position. The FT‐IR spectra indicated that the HA from the soil at the lowest topographic position tended to have a slightly higher content of carboxyl groups than the HAs from soils at higher topographic levels. The observed fluorescence was attributed to the presence of condensed aromatic moieties and/or conjugated unsaturated systems of various complexity in the HA macromolecules.
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