Soil Science · 1991 · 44 citations · 0 references
BiogeochemistryEnvironmental ChemistryEngineeringEnvironmental EngineeringChemical FormElectron Paramagnetic ResonanceBioremediationSoil FunctionEnvironmental RemediationSoil ChemistryHumic AcidAnalytical ChemistryChemistryBrazilian SoilSoil Biochemistry
The technique of electron paramagnetic resonance was used to examine the formation of micronutrients-humic substances complexes extracted from a Brazilian soil. Results indicate that there are two types of copper (II) complexes, one with oxygen and another with nitrogen atoms, in humic acids while in fulvic acids only the copper complexed with oxygen was detected. The iron (III) complex signal with g = 4.3 was observed in both humic acid and fulvic acid. The concentration of free radicals (semiquinone) detected in humic acids (1015 spins/g) was bigger than in fulvic acids (1014 spins/g) due to a greater humification degree confirmed by elementary analysis and E4/E6 ratio measurements.