01377naa a2200253 a 450000100080000000500110000800800410001910000160006024501510007626000060022752004660023365000210069965300210072065300230074165300300076465300350079465300100082970000190083970000230085870000170088170000200089870000240091877301810094210294242006-01-27               bl ---       0--  u    #d1 aROSA, A. H.  aMultimethod study of the degree of humidification of humic substances extrated from different tropical soil profiles in Brazil's Amazonian region.  c0  aThis work consisted of determining the degree of humification of humic substances (HS) extracted from six different Amazonian soils collected from flooded and unflooded regions at different depths (0-10, 10-20, 20-40, and 60 cm). The humic substances were extracted according to procedures recommended by the International Humic Substances Society and characterized using elemental analysis, electron paramagnetic resonance (EPR), and fluorescence spectroscopy.  ahumic substances  aAmazonian region  aElemental analysis  aFluorescence spectroscopy  aSemiquinone-type free radicals  aSoils1 aSIMÕES, M. L.1 aOLIVEIRA, L. C. de1 aROCHA, J. C.1 aMARTIN NETO, L.1 aMILORI, D. M. B. P.  tGeoderma: an international journal of soil science, Amsterdamgv. 127, n. 1-2, p. 1-10, July 2005. Disponível em: http://elsevier.com/locate/geoderma. Acesso em: 09 jan. 2006.