Interações entre íons Hg(II) e substâncias húmicas extraídas de diferentes solos da Bacia do Médio Rio Negro, Amazônia
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Data
2006-05-19
Autores
Bellin, Iramaia Corrêa [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Neste trabalho caracterizaram-se amostras de solo e substâncias húmicas (SH) extraídas de diferentes solos da Bacia do Médio Rio Negro e também determinaram-se a capacidade de complexação de íons Hg(II) por SH e constantes de troca entre espécies metálicas originalmente complexadas às SH por íons Hg(II). As amostras de solos foram caracterizadas através do teor de matéria orgânica, análises elementar e granulométrica. Os resultados mostraram que os teores de matéria orgânica para as amostras de solo diminuíram com a profundidade. Com base nos resultados de análise granulométrica feita nas amostras de solos, caracterizou-se o aumento dos teores de argila em função da profundidade com a conseqüente diminuição dos teores de areia e silte. As substâncias húmicas extraídas de amostras de solos coletados na Bacia do Médio Rio Negro-AM foram caracterizados por análise elementar, ressonância paramagnética eletrônica e ressonância magnética nuclear. Os resultados mostraram que, em função da profundidade, os valores das razões atômicas C/N foram praticamente constantes ao contrário das razões C/O e C/H, as quais diminuíram. As concentrações de radicais livres do tipo semi-quinona das substâncias húmicas variaram de 0,08 a 5,38 x 1018 spins g-1 de carbono, indicando diferença entre os níveis de humificação das SH extraídas de solos amazônicos. As SH extraídas de solos de regiões alagáveis apresentaram maiores concentrações de spins em relação às SH extraídas de regiões não alagáveis, indicando influência da umidade no processo de humificação.
In this research were characterized humic substances (HS) and soil samples extracted from Rio Negro-AM Medium Basin and capacity of complexation (CC) of Hg(II) by HS and constants of exchange between metallic species originally complexed in the HS by Hg(II) had also been determined. The soil samples were characterized through organic material composition, elemental and granulometry analysis. The results showed decreasing of the organic material composition with the depth. According to the results taken, was characterized an increasing in the composition of clay with the depth, but in the other hand, a reduction in silt and sand composition. The humic substances extracted of soil samples from Rio Negro-AM Medium Basin were characterized by elemental analysis, electronic paramagnetic resonance and nuclear magnetic resonance. The results had shown that, in function of the depth, the atomic ratio values C/N were constants, while the atomic ratio C/O and C/H decresed. The concentrations of free radicals of the humic substances were 0.08 to 5.38 x 1018 spins g-1 of carbon, indicating difference in the humification levels of HS extracted from Amazonian soils. The HS extracted in flooded regions showed bigger spins concentrations comparing to ones extracted in unflooded regions, showing that the humidity influences in the process of humification. The NMR of 13C dates showed the sequence of percentage of kind of carbon: aliphatic > ethers/hydroxyls > carboxyls/esthers/amides > aromatics > phenols @ carbonyls of aldehydes and ketones for HS samples extracted of the differences profiles of the Amazonian soils studied.
In this research were characterized humic substances (HS) and soil samples extracted from Rio Negro-AM Medium Basin and capacity of complexation (CC) of Hg(II) by HS and constants of exchange between metallic species originally complexed in the HS by Hg(II) had also been determined. The soil samples were characterized through organic material composition, elemental and granulometry analysis. The results showed decreasing of the organic material composition with the depth. According to the results taken, was characterized an increasing in the composition of clay with the depth, but in the other hand, a reduction in silt and sand composition. The humic substances extracted of soil samples from Rio Negro-AM Medium Basin were characterized by elemental analysis, electronic paramagnetic resonance and nuclear magnetic resonance. The results had shown that, in function of the depth, the atomic ratio values C/N were constants, while the atomic ratio C/O and C/H decresed. The concentrations of free radicals of the humic substances were 0.08 to 5.38 x 1018 spins g-1 of carbon, indicating difference in the humification levels of HS extracted from Amazonian soils. The HS extracted in flooded regions showed bigger spins concentrations comparing to ones extracted in unflooded regions, showing that the humidity influences in the process of humification. The NMR of 13C dates showed the sequence of percentage of kind of carbon: aliphatic > ethers/hydroxyls > carboxyls/esthers/amides > aromatics > phenols @ carbonyls of aldehydes and ketones for HS samples extracted of the differences profiles of the Amazonian soils studied.
Descrição
Palavras-chave
Substâncias húmicas, Solos - Bacia do Rio Negro (AM), Mercurio - Bacia do Rio Negro (AM), Solos - Matéria orgânica, Humic substances, Soil samples
Como citar
BELLIN, Iramaia Corrêa. Interações entre íons Hg(II) e substâncias húmicas extraídas de diferentes solos da Bacia do Médio Rio Negro, Amazônia. 2006. 103 f. Tese (doutorado) - Universidade Estadual Paulista, Instituto de Química, 2006.