01721nam a2200241 a 450000100080000000500110000800800410001910000130006024500780007326002710015152008740042265000230129665000100131965000090132965300250133865300170136365300090138065300080138970000190139770000200141670000220143670000210145813347882022-04-06       2008    bl uuuu     u00u1 u    #d1 aSONG, G.  aChar and humin fractions in Amazonian dark earths.h[electronic resource]  aIn: INTERNATIONAL MEETING OF THE INTERNATIONAL HUMIC SUBSTANCES SOCIETY, 14., 2008, Saint Petersburg. From molecular understanding to innovative applications of humic substances: proceedings... Moscow: Lomonosov Moscow State University, 2008. v. 1, p. 311-314.c2008  aThe high and specific SOM contents of the Amazonian Dark Earths (ADE, Terra Preta de Índios), and their high contents of P and Ca provide high natural fertility to the soils. Char or black carbon (B C) plays a major role for the SOM stability in ADE soils (1) and it also provides a significant potential for carbon sequestration and sustainable ecosystems (2). There are several studies of the humic acids (HAs) of ADE soils (e.g., 3 and 4). However, because of the difficulties in isolation, there is less awareness of humin, the most abundant SOM component, and of the interaction mechanisms of recalcitrant BC with SOM (especially humin) and clays. In this study, humic materials were extracted using the IHSS procedure and by exhaustive sequential extraction procedures. Isotopic 13C analyses, and solid-state 13C NMR spectroscopy were used for characterizations.  adimethyl sulfoxide  ahumin  aurea  aAmazonian dark earth  ablack carbon  achar  aNMR1 aNOVOTNY, E. H.1 aHAYES, M. H. B.1 aAZEVEDO, E. R. de1 aBONAGAMBA, T. J.