Correlation of spectroscopic indicators of humification with mean annual rainfall along a temperate grassland climosequence

Martin‐Neto, Ladislau; Rosell, R. A.; Sposito, Garrison

doi:10.1016/s0016-7061(97)00089-x

Cited by 92 publications

(77 citation statements)

References 15 publications

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“…These parameters are inter-linked by the degree of humification. Martin-Neto et al 18 encountered significant positive linear correlation between the OFR concentration and the pluviometric index. According to Stevenson,7 the C/N atomic ratios is proportional to the HS humification degree.…”

Section: Samplesmentioning

confidence: 97%

“…To determine the relative concentration of semiquinone-type free radicals (OFR), also defined in the text as concentration of spins (in spins g -1 of C); the signal area of the AHS samples was compared with a standard ("strong pitch") of known concentration of spins supplied by Bruker. It was used too a secondary standard in according to Singer's method 18,30 to detect possible alterations in the Q-values of the EPR cavity. The experimental parameters were the following: 0.2 mW for the microwave power (determined by a power saturation experiment) 31 100 kHz for the modulation frequency; 0.1 mT for the modulation amplitude; 2.56 ms for the time constant and 10.24 ms for time conversion.…”

Section: Electronic Paramagnetic Resonance (Epr)mentioning

confidence: 99%

“…The properties of HS in the environment are influenced by their composition and structural characteristics, being controlled by the humification process of the OM 14,15 and are dependant on the type of soil, 16 vegetation 17 and climatic conditions. 18 Humification is defined as the transformation of macromorphologically identifiable matter into amorphous compounds, as a rule involving the changes that occur in vegetal residues or soil organic matter. It has been related to the preferential oxidation of plant polysaccharides, the selective preservation of more recalcitrant organic compounds such as lignin and phenolic structures, and to the incorporation of organic compounds of microbial origin.…”

Section: Introductionmentioning

confidence: 99%

“…45,46 It has been shown that the OFR concentration is proportional to the humification of the SOM. 18,44,45,48,49 Normally, humification process is related to the content of aromatic compounds. 50,51 Along with this, the determination of the OFR concentration gives an indirect estimation of the degree of aromaticity of the HS.…”

mentioning

confidence: 99%

“…However, these values are below the values normally encountered for humic acids from soil. 18,52 The statistical methods of extrapolational analysis, hierarchical cluster analysis (HCA) and principal component analysis (PCA) were used to interpret the experimental data generated from the different determinations using STATISTICA 6.0 software. Hierarchical cluster analysis (Figure 2) showed the formation of three main groups: (A) H/C atomic ratios, aliphatic carbon, carbonyl carbon and fluviometric index; (B) C/N, carboxyl carbon, OFR, and pluviometric index; (C) C/ O, pH, ether, aromatics, phenolics and the concentration of mercury.…”

mentioning

confidence: 99%

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The influence of seasonalness on the structural characteristics of aquatic humic substances extracted from Negro River (Amazon State) waters: interactions with Hg(II)

Oliveira¹,

Sargentini²,

Rosa³

et al. 2007

J. Braz. Chem. Soc.

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Neste trabalho, substâncias húmicas foram extraídas de amostras de água coletadas mensalmente na Bacia do Rio Negro-AM para estudar suas propriedades no ambiente amazônico e interações com íons mercúrio, considerando a influência da variação sazonal na sua formação. Os parâmetros razões atômicas C/H, C/N e C/O, grupos funcionais, radicais livres do tipo semiquinona, pH, índices pluviométricos e fluviométricos, concentrações de mercúrio foram interpretados por análise hierárquica de cluster (AHC) e análise de componentes principais (ACP). As análises estatísticas mostraram que, quanto maior o índice pluviométrico e menor o índice fluviométrico maior o grau de humificação das substâncias húmicas aquáticas. A seguinte ordem decrescente do grau de humificação das SHA coletadas mensalmente pode ser estabelecida: Nov/02 a Fev/03 > Mar/02 a Mai/02 > Jun/02 a Out/02. As maiores concentrações de mercúrio foram determinadas nas amostras mais humificadas, sugerindo que devido a rearranjos inter e/ou intramoleculares, quanto maior o grau de humificação maior a afinidade dos íons Hg(II) pelas substâncias húmicas aquáticas.In this work, humic substances were extracted from water samples collected monthly from the Negro River basin in the Amazon state (Brazil) to study their properties in the Amazonian environment and interactions with the mercury ion considering the influence of seasonalness in this formation. The C/H, C/N and C/O atomic ratio parameters, functional groups, concentration of semiquinone-type free radicals, pH, pluviometric and fluviometric indices, and mercury concentrations were interpreted using hierarchical cluster analysis (HCA) and principal component analysis (PCA). The statistical analyses showed that when the pluviometric index was greater and the fluviometric index was smaller, the degree of humification of aquatic substances was greater. The following decreasing order of the degree of humification of the AHS collected monthly was established: Nov/02 to Feb/03 > Mar/02 to May/02 > Jun/02 to Oct/02. The greatest concentrations of mercury were detected in more humidified samples. These results suggest that due to inter and/or intra-molecular rearrangements, the degree of humification of aquatic humic substances is related to its affinity for Hg(II) ions.Keywords: aquatic humic substance, seasonality, Negro River, Amazon, mercury IntroductionFresh water streams have an important function in the global carbon cycle in that they conduct organic matter (OM) of terrestrial origin and transfer it to the oceans. 1 The Amazonian region is home to the most extensive fluvial system which also has greatest liquid mass of the whole earth and it is covered by the largest pluvial tropical forest. According to Bluntschli, 2 the circulation of marine water through the atmospheric compartment above the forest and then from the forest across the fluvial plains again to the sea has a decisive 861 Oliveira et al. Vol. 18, No. 4, 2007 function in the Amazonian ecosystem. According to Sioli, 3 the forest and the regimes...

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Section: Samplesmentioning

confidence: 97%

Section: Electronic Paramagnetic Resonance (Epr)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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The influence of seasonalness on the structural characteristics of aquatic humic substances extracted from Negro River (Amazon State) waters: interactions with Hg(II)

Oliveira¹,

Sargentini²,

Rosa³

et al. 2007

J. Braz. Chem. Soc.

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Applications of Vibrational Spectroscopy in Soil and Environmental Sciences

Johnston

Wang

2001

Handbook of Vibrational Spectroscopy

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The sections in this article are Introduction Sampling Methods Attenuated Total Reflection Diffuse Reflection Transmission Micro‐ R aman Spectroscopy Using Molecular Probes to Study Environmental Particles Water Oxyanions Organic Probe Molecules Organic Cations Organic Anions Neutral Organic Compounds IR and R aman Studies of Humic Substances Summary

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EPR, FTIR, Raman, UV–Visible Absorption, and Fluorescence Spectroscopies in Studies of NOM

Martin‐Neto

Milori

Silva

et al. 2009

Biophysico‐Chemical Processes Involving Natural Nonliving Organic Matter in Environmental Systems

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Correlation of spectroscopic indicators of humification with mean annual rainfall along a temperate grassland climosequence

Cited by 92 publications

References 15 publications

The influence of seasonalness on the structural characteristics of aquatic humic substances extracted from Negro River (Amazon State) waters: interactions with Hg(II)

The influence of seasonalness on the structural characteristics of aquatic humic substances extracted from Negro River (Amazon State) waters: interactions with Hg(II)

Applications of Vibrational Spectroscopy in Soil and Environmental Sciences

EPR, FTIR, Raman, UV–Visible Absorption, and Fluorescence Spectroscopies in Studies of NOM

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