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Registro Completo |
Biblioteca(s): |
Embrapa Instrumentação. |
Data corrente: |
28/04/2003 |
Data da última atualização: |
28/04/2003 |
Autoria: |
NOVOTNY, E. H.; MARTIN-NETO, L. |
Afiliação: |
Embrapa Instrumentação Agropecuária, São Carlos, SP. |
Título: |
Effects of humidity and metal ions on the free radicals analysis of peat humus. |
Ano de publicação: |
2002 |
Fonte/Imprenta: |
Geoderma, Amsterdam, v. 106, p. 305-317, 2002. |
Idioma: |
Inglês |
Conteúdo: |
The effects of humidity and metal ions in the determination of humic organic free radicals concentration (HOFRC) were studied by electron paramagnetic resonance (EPR). Increasing the sample humidity caused a decrease in both HOFRC, probably due to free radicals recombination, and in the derivative peak-to-peak line width, probably due to a higher spin-spin relaxation time (T2) as the molecular mobility increasd (shorter correlation time). Diamagnetic ions did not affect the HOFRC, while paramagnetic ions induced an intense HOFRC decrease. This effect was associated with dipolar-relaxation enhancement at high (above 0, 01%) paramagnetic ion concentrations, since the inhomogeneity parameter decreased to less than I. Further, a possible exchange interaction an/or shift in the free radicals equilibrium reactions might have occurred at low paramagnetic ion concentrations (below 0,01%. |
Palavras-Chave: |
Radicais livres; Ressonânica paramagnética; Substâncias húmicas. |
Thesaurus Nal: |
free radicals; ions. |
Categoria do assunto: |
-- |
Marc: |
LEADER 01440naa a2200193 a 4500 001 1024628 005 2003-04-28 008 2002 bl --- 0-- u #d 100 1 $aNOVOTNY, E. H. 245 $aEffects of humidity and metal ions on the free radicals analysis of peat humus. 260 $c2002 520 $aThe effects of humidity and metal ions in the determination of humic organic free radicals concentration (HOFRC) were studied by electron paramagnetic resonance (EPR). Increasing the sample humidity caused a decrease in both HOFRC, probably due to free radicals recombination, and in the derivative peak-to-peak line width, probably due to a higher spin-spin relaxation time (T2) as the molecular mobility increasd (shorter correlation time). Diamagnetic ions did not affect the HOFRC, while paramagnetic ions induced an intense HOFRC decrease. This effect was associated with dipolar-relaxation enhancement at high (above 0, 01%) paramagnetic ion concentrations, since the inhomogeneity parameter decreased to less than I. Further, a possible exchange interaction an/or shift in the free radicals equilibrium reactions might have occurred at low paramagnetic ion concentrations (below 0,01%. 650 $afree radicals 650 $aions 653 $aRadicais livres 653 $aRessonânica paramagnética 653 $aSubstâncias húmicas 700 1 $aMARTIN-NETO, L. 773 $tGeoderma, Amsterdam$gv. 106, p. 305-317, 2002.
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Embrapa Instrumentação (CNPDIA) |
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Registros recuperados : 273 | |
1. | | NOVOTNY, E. H. Biochar. Revista Opiniões, Ribeirão Preto, p. 45, jun./ago. 2008.Tipo: Artigo de Divulgação na Mídia |
Biblioteca(s): Embrapa Solos. |
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20. | | NOVOTNY, E. H.; MARTIN NETO, L. Propriedades coloidais da matéria orgânica. In: SANTOS, G. de A.; SILVA, L. S. da; CANELLAS, L. P.; CAMARGO, F. A. de O. (ed.). Fundamentos da matéria orgânica do solo: ecossistemas tropicais & subtropicais. 2. ed. rev. e atual. Porto Alegre: Metrópole, 2008. cap. 4, p. 27-43.Tipo: Capítulo em Livro Técnico-Científico |
Biblioteca(s): Embrapa Solos. |
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Registros recuperados : 273 | |
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