GEOC 93 |
| Researches to understand mechanisms of stabilization and reaction of humic material, in soil and water systems, has been conducted mainly with humic substances extracted from tropical areas (different regions of Brazil). Using some spectroscopic techniques, as 13C nuclear magnetic resonance (NMR), electron paramagnetic resonance (EPR), UV-Visible light and laser induced fluorescence, it was demonstrated the decrease of humification degree of humic substances in areas under soil carbon sequestration. This result suggested possibility of structural change of humic substances, in relatively short term, in agreement with recent model of supramolecular structure to humic substances. In other research, with soluble humic substances, pH-dependent hydrophobic interactions were detected using spin-label methodology, by EPR. Also using EPR the spin-trap methodology was applied to identify mechanisms of formation and suppression of hydroxyl free radical in aquatic humic substances. |
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Physical Chemistry of Soil and Aquifer Systems: A Symposium in Honor of Garrison Sposito
8:15 AM-11:55 AM, Tuesday, 12 September 2006 Moscone Center -- Room 256, Oral
Division of Geochemistry |