The interaction behavior of humic acids with uranium(VI) and the influence of humic substances on the migration behavior of uranium was investigated. A main focus of this work was the synthesis of four different humic acid model substances and their characterization and comparison to the natural humic acid from Aldrich. A radiometric method for the determination of humic acid functional groups was applied in addition to conventional methods for the determination of the functionality of humic acids. The humic acid model substances show functional and structural properties comparable to natural humic acids. Modified humic acids with blocked phenolic OH were synthesized to determine the influence of phenolic OH groups on the complexation behavior of humic acids. A synthesis method for 14C-labeled humic acids with high specific activity was developed. The complexation behavior of synthetic and natural humic acids with uranium(VI) was investigated by X-ray absorption spectroscopy, laser-induced fluorescence spectroscopy and FTIR spectroscopy. The synthetic model substances show an interaction behavior with uranium(VI) that is comparable to natural humic acids. This points to the fact that the synthetic humic acids simulate the functionality of their natural analogues very well. For the first time the influence of phenolic OH groups on the complexation behavior of humic acids was investigated by applying a modified humic acid with blocked phenolic OH groups. The formation of a uranyl hydroxy humate complex was identified by laserspectroscopic investigations of the complexation of Aldrich humic acid with uranium(VI)at pH 7. The migration behavior of uranium in a sandy aquifer system rich in humic substances was investigated in column experiments. A part of uranium migrates non-retarded through the sediment, bound to humic colloids. The uranium migration behavior is strongly influenced by the kinetically controlled interaction processes of uranium with the humic colloids. The influence of humic acids on the sorption of uranium(VI) onto phyllite was investigated in batch experiments using two different humic acids. The uranium(VI) sorption onto the rock phyllite is influenced by the pH-dependent sorption behavior of the humic acids.

A agropecuária pode ser uma aliada importante para a mitigação de gases causadores do efeito estufa. A recuperação direta de pastagens degradadas, a adoção do manejo intensivo das pastagens e a integração lavoura-pecuária (ILP) têm apresentado grande potencial na diminuição dos gases de efeito estufa (GEE), devido à elevada produção de massa de forragem das gramíneas tropicais, e consequentemente acumulando matéria orgânica no solo. Estudos sobre a dinâmica e estabilidade da matéria orgânica do solo (MOS) são necessários, uma vez que a MOS constitui o maior reservatório dinâmico de carbono (C) da superfície terrestre, e qualquer variação na abundância e composição desta, perfaz importantes efeitos na dinâmica que ocorre entre os sistemas de armazenamento de carbono. Pode-se avaliar as modificações químicas sofridas pela MOS utilizando suas propriedades de fluorescência. Nesse contexto, o objetivo desse trabalho foi avaliar ácidos húmicos (AH), extraídos de diferentes sistemas de manejo pecuário, e verificar se os mesmos se alteram nesses manejos. O experimento estava localizado na unidade da Embrapa Pecuária Sudeste, São Carlos-SP, sendo os sistemas de manejos o irrigado, sequeiro, em recuperação, degradado e a mata nativa como área de referência. Foram coletadas amostras de solo das cinco áreas de estudo, e posteriormente, realizou-se a extração dos AH do solo. As técnicas utilizadas na caracterização dos AH foram análise elementar (CHNS), espectroscopia de infravermelho com transformada de Fourier (FTIR), fluorescência bidimensional e tridimensional e supressão de fluorescência por metais. Em geral, a MOS presente na superfície apresentou-se mais lábil e fresca, já a MOS em camadas mais profundas se mostrou mais recalcitrante e humificada. O manejo degradado apresentou pouco acúmulo de carbono no solo, e também um AH rico em compostos aromáticos e com alto valor de humificação. Os manejos de sequeiro e em recuperação mostraram comportamento semelhante ao da mata nativa, apresentando um alto acúmulo de carbono no solo, mas uma estrutura dos AH mais lábeis, nas camadas superficiais e baixos índices de humificação. A área irrigada teve baixa incorporação de carbono no solo, igualmente à área degradada, apresentando também um AH mais humificado e com estruturas mais conjugadas. O experimento de supressão de fluorescência mostrou valores menores da constante de estabilidade condicional (K), para os manejos irrigado e degradado, mostrando que os mesmos podem ter perdido alguns sítios ativos, deixando a MOS menos reativa no solo. Em relação às análises de fluorescência tridimensional, as amostras de AH tiveram duas componentes de fluorescência, ambas de origem tipo ácido húmico terrestre. Pode-se concluir que a recuperação de áreas degradadas é um caminho viável para a estocagem de MOS, uma vez que a área em recuperação apresentou valores semelhantes aos da mata nativa, porém a estabilidade desse carbono no solo deve ser monitorada constantemente. O excesso de irrigação e a degradação de pastagens não apresentaram um comportamento positivo para a MOS, ambos os manejos deixaram a MOS com poucos sítios ligantes, muito humificada mesmo em superfície e com pouco acúmulo de carbono no solo, deixando essa matéria orgânica pouco interativa, afetando assim a produtividade do solo. / Agricultural and livestock can be a great allied important for the mitigation of greenhouse gas effect. The direct recovery of degraded pastures, the adoption of intensive management of pasture and crop-livestock integration (CLI) have shown great potential in reducing greenhouse gas (GHG) due to the high mass of forage production of tropical grasses, and thus accumulating organic matter in the soil. Studies of the dynamics and stability of the soil organic matter (SOM) is needed, since the SOM constitutes the largest dynamic carbono (C) reservoir from the land surface, and any variation in the abundance and composition thereof, adds up significant effects on the dynamics that occurs between the carbon storage systems. Can be evaluated the chemical modifications that occurred by the SOM using their fluorescence properties. In this context, the objective of this study was to evaluate humic acid (HA), taken from different livestock management systems, and verify that the HA have changes in these managements. The experiment was located in the unit Embra Pecuária Sudeste, São Carlos-SP, with the managements systems irrigated, dry, in recovery, degraded and native forest as a reference area. Soil samples were collected from five study areas, and later was carried out the extraction of soil AH. The techniques used in the characterization of HA was elemental analysis (CHNS), Fourier transform infrared spectroscopy (FTIR), two-dimensional, three-dimensional fluorescence and fluorescence quenching. In general, the SOM on the surface presented is more labile and fresh, already the SOM in deeper layers was more recalcitrant and humified. Degraded management showed little accumulation of carbon in the soil, an HA rich in aromatic compounds and with high value humification. The dry and in recovery managements showed similar behavior to that the native forest, with a high accumulation of carbon in the soil, but a structure of HA more labile, in the surface layers and low levels of humidification. The irrigated area had low incorporation of carbon in the soil, as well the degraded area, also presenting an HA more humified and with more conjugated structures. The fluorescence quenching experiment showed lower values of the conditional stability constant (K) for irrigation and degraded managements, showing that they may have lost some active sites, leaving the less reactive SOM soil. In relation to the tridimensional fluorescence analysis, HA samples had two fluorescent components, both source type terrestrial humic acid. Can be concluded that the recovery of degraded areas is a viable way to SOM storage, since that the area in recovery showed values similar to those of native forest, but the stability of carbon in the soil must be monitored constantly. Excess irrigation and pasture degradation did not show a positive behavior for SOM, both managements left SOM with few binding sites, very much humified in surface and low carbon accumulation in the soil, leaving this organic matter little interactive, affecting thus soil productivity.

Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2017-06-27T14:38:40Z No. of bitstreams: 1 2010 - Adierson Gilvani Ebeling.pdf: 3744657 bytes, checksum: 0458139e287a489573818b522e4c02de (MD5) / Made available in DSpace on 2017-06-27T14:38:40Z (GMT). No. of bitstreams: 1 2010 - Adierson Gilvani Ebeling.pdf: 3744657 bytes, checksum: 0458139e287a489573818b522e4c02de (MD5) Previous issue date: 2010-08-27 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico, CNPq, Brasil. / The Histosols have a small geographic extension in the Brazilian territory; however, they are intensively used in family agriculture systems and have a great environmental importance. The drainage of Histosols leads to the subsidence process and other changes in the soil organic matter (SOM), with consequences in their characteristics and potential. The nature of humic substances (HSs) is determinant in the alterations of the Histosols. The characterization of the HSs allows the understanding of processes of SOM transformation in the Histosols, and their environmental impact. The objectives of this study were: to characterize Histosols from different environments and land usage intensity; and to evaluate alterations in humic fractions of SOM, by using elemental composition analyses, spectroscopic, thermal degradation, and nuclear magnetic resonance (NMR) techniques. The study was developed in eight Histosols, from the States of Rio de Janeiro, Maranh?o and Paran?, in Brazil. Their chemical properties: total organic carbon (TOC), pH, sum of bases (SB), H+, Al3+, cation exchange capacity (CEC), and V%; and physical properties: bulk density (BD), MR, MM, and OMD, were evaluated. Also, the quantitative fractionating of the HSs: fulvic acid (C-FAF), humic acid (CHAF), and humin (C-HUM), and C-FAH/C-FAF relations, C-EA/C-HUM (C-EA = C-FAF + C-FAH). The humic acids were extracted using the method of the International Humic Substances Society (IHSS), and evaluated by different techniques. The chemical attributes varied with the intensity of burning and agricultural usage. Though, in general, the Histosols presented low natural fertility, and it was related to the humic acid fraction (high ratio CFAH/ C-FAF). Amongst the SOM fractions the HUM predominated, with an average value of 59.98% of total carbon determined by the CHN; followed by the FAH. The C-FAH/C-FAF ratio diminished with the increase of agriculture usage intensity. The results of the TGI (Thermal Gravimetric Index) suggested strong resistance to thermal degradation of majority of the organic horizons. The elemental composition (%C, %H, %N, %O) of the humic acids showed large amplitude of variation between the horizons, but no pattern was observed between the Histosols. The increase of carbon content, the high values of TGI, and the reduction of oxygen content in the humic acids (HA) might explain the high thermal decomposition resistance found in the HA extracted form the Histosols. A correlation between H/C and TGI was observed, where the lower values of H/C were related to the highest resistance of the humic acids to thermal degradation. The spectroscopic and NMR techniques allowed characterizing compounds and groups of substances in the HA, showing the great potential of these tools in studies of HS from Histosols. The multivariate methods allowed a combined analysis of techniques applied in the study, showing a group of labile and recalcitrance materials in the soils. The results, in general, indicated the fragility of the Histosols areas, in terms of agricultural management and the formation environment. Their importance for the environment should be priority in comparison to agricultural usage, mainly due to their relevant part in the aquifers preservation. / Os Organossolos t?m pequena representatividade geogr?fica no Brasil, entretanto, s?o utilizados intensamente em modelos de agricultura familiar e t?m grande import?ncia ambiental. Por?m, a sua drenagem conduz ao processo de subsid?ncia e outras modifica??es na mat?ria org?nica do solo (MOS), com implica??es nas caracter?sticas dos Organossolos e em sua potencialidade. A natureza das subst?ncias h?micas (SHs) ? determinante nessas altera??es nos Organossolos. A caracteriza??o das SHs permite a compreens?o dos processos de transforma??o da MOS nos Organossolos e seu impacto no ambiente. Os objetivos deste trabalho foram: caracterizar Organossolos em v?rios ambientes e intensidade de uso agr?cola e avaliar altera??es nas fra??es humificadas da MO, atrav?s de t?cnicas de an?lise da composi??o elementar, espectrosc?picas, termodegradativas e de resson?ncia magn?tica nuclear (RMN). Foram estudados oito perfis de solos, nos Estados do Rio de Janeiro, Maranh?o e Paran?. Foram avaliadas as suas propriedades qu?micas: carbono org?nico total (COT), pH, soma de bases (SB), H+, Al3+, CTC e V%; e propriedades f?sicas: densidade do solo (Ds), RM, MM e DMO. Al?m do fracionamento quantitativo das SHs: ?cidos f?lvicos (C-FAF), ?cidos h?micos (C-FAH) e humina (C-HUM), e rela??es C-FAH/C-FAF, C-EA/CHUM (C-EA = C-FAF + C-FAH). Os ?cidos h?micos (AH) foram extra?dos pelo m?todo da Sociedade Internacional de Subst?ncias H?micas (IHSS) e avaliados por distintas t?cnicas. Os atributos qu?micos variaram com o efeito das queimadas e da intensidade de uso agr?cola; por?m, em geral, os Organossolos apresentaram baixa fertilidade natural, a qual, em geral, esteve relacionada ? fra??o ?cido h?mico (maior raz?o C-FAH/C-FAF). Dentre as fra??es da MO, a HUM predominou, com valor m?dio de 59,98% do carbono total determinado pelo CHN, seguida da FAH. A rela??o C-FAH/C-FAF diminuiu a medida que o uso agr?cola ? intensificado. Os dados do ITG (?ndice Termogravim?trico) sugeriram forte resist?ncia ? termodegrada??o para a maioria dos horizontes org?nicos. A composi??o elementar (%C, %H, %N, %O) dos ?cidos h?micos apresentou grande amplitude entre os horizontes, por?m sem padr?o diferenciado entre os Organossolos. O aumento do conte?do de carbono, os altos valores de ITG e a diminui??o do conte?do de oxig?nio nos ?cidos h?micos podem explicar a maior resist?ncia a termodecomposi??o dos AH extra?dos dos Organossolos. Foi observada correla??o entre a raz?o H/C e o ITG, onde os menores valores de H/C estiveram relacionados a maior resist?ncia dos AH ? termodegrada??o. As t?cnicas espectrosc?picas e de RMN permitiram caracterizar compostos e grupamentos nos AH, demonstrando o potencial dessas ferramentas nos estudos de SHs provenientes de Organossolos. Os m?todos de an?lise multivariada permitiram uma avalia??o conjunta das t?cnicas utilizadas, mostrando um grupo de amostras l?beis e recalcitrantes nos solos. Os resultados encontrados, em geral, indicam a fragilidade das ?reas de Organossolos, em fun??o do manejo para agricultura e do seu ambiente de forma??o. A sua import?ncia em termos ambientais deveria ser priorizada em rela??o ao uso agr?cola, principalmente pelo papel relevante na preserva??o de aqu?feros.

[pt] Rejeitos da mineração contendo grandes quantidades de finos são constantemente descartados em barragens. A recuperação da água contida nesses rejeitos depende, dentre outros fatores, da remoção de reagentes residuais e material particulado fino, que, devido às suas características de tamanho e cargas superficiais requerem tempos de sedimentação impraticáveis industrialmente. Partículas em suspensão, com diâmetro médio inferior a 2 micrometro, não podem ser removidas por sedimentação simples pois, devido às suas cargas superficiais, permanecem em repulsão mútua, promovendo uma estabilidade eletrostática da polpa. Entretanto, o estado de dispersão dessas partículas está diretamente relacionado ao potencial eletrostático de superfície, sendo necessárias etapas de desestabilização de cargas e agregação, por meio de coagulação e floculação. Na indústria mineral as poliacrilamidas são os polímeros comerciais mais comumente utilizados; porém, com a demanda por floculantes de menor custo e ambientalmente amigáveis, como os polímeros naturais de uso ainda incipiente, a quitosana e o ácido húmico passam a ser atrativos para sua aplicação em polpas minerais. Para este caso de estudo serão avaliados um rejeito de níquel e lama vermelha, ambos provenientes de unidades industriais. O pH é uma variável muito influenciável no processo, porém mediante a análise do potencial zeta foram medidas as cargas superficiais resultantes e se determinou o pH de trabalho para cada uma das polpas. A qualidade dos flocos formados tem forte dependência com as condições operacionais de formação como tipo de reagentes e suas combinações, porém mediante a utilização do planejamento experimental foram estudadas variáveis como concentração de sólidos, dosagens de quitosana e de ácido húmico, velocidade e tempo de agitação. Os parâmetros do processo foram otimizados por meio da obtenção e ajuste de modelos matemáticos. Os ensaios de floculação tiveram como variável de resposta a turbidez do sobrenadante e os resultados foram ajustados atendendo às normas ambientais vigentes para reuso da água. Para o rejeito de Ni, em um pH próximo de 7, obteve-se um modelo quadrático, que conferido experimentalmente com as condições otimizadas deu uma resposta de turbidez de 32 NTU. Para o caso da lama vermelha obtiveramse dois modelos: em pH igual a 12 obteve-se um modelo linear, que gerou uma resposta de turbidez de 33 NTU e em pHigual a 8 obteve-se um modelo quadrático, conferido experimentalmente uma resposta de turbidez de 31 NTU. Dessa forma, nota-se que, para os polímeros estudados, é possível reduzir a turbidez de fluxos de sobrenadantes com eficiência de até 90 por cento. / [en] Mining waste containing large amounts of fines are constantly disposed of in dams. The recovery of water contained in these wastes depends, among other factors, the removal of residuals reagents and fine particulate material, which due to their size and surface charge characteristics require of sedimentation times impractical industrially. Suspended particles with an average diameter of less than 2 micrometre, can not be removed by simple sedimentation by reason of their surface charges, remain in mutual repulsion, promoting an electrostatic stability of the pulp. However, the dispersion state of the particles is directly related to the electrostatic surface potential, and steps necessary to destabilize charges and aggregation, through coagulation and flocculation. Polyacrylamides are the most commonly used commercial polymers at the mineral industry; however, the demand for flocculants of lower cost and environmentally friendly, such as natural polymers have incipient use as chitosan and humic acid, become attractive for application in mineral slurries, for this case study will be evaluated the tailings of Ni and the red mud. pH is a very influenceable variable in the process but by an analysis of the zeta potential were measured of resulting surface charges and determined of pH for each of the slurries. The quality of the flakes have formed strong dependence on operating conditions of formation as a kind of reagents and their combinations, but by using the experimental design were studied variables such as of solids concentration, chitosan, humic acid, stirring speed and stirring time. With the obtained mathematical models, were the optimizations conducted of the process parameters. In tests of flocculation, it had turbidity as response variable of the supernatant and the results were adjusted taking into account the environmental standards for water reuse. To Ni in a pH next to 7, there was obtained a quadratic model, given the conditions optimized experimentally gave a turbidity response of 32 NTU. For the case of red mud was obtained two models at pH 12 was obtained as a linear model given experimentally gave a turbidity response of 33 NTU and pH 8 was obtained a quadratic model, given experimentally has a turbidity response of 31 NTU, which show that it is possible to reduce overflow the turbidity from 500 NTU to less than 50 NTU.

The presented diploma thesis deals with the study of interactions between humic acids as the main component of soil organic matter with a model organic pollutant presented by cationic surfactant Septonex (which was expected to interact positively with humic acids due to its charge) through unconventional combination of dialysis and diffusion techniques realized in diffusion cells together with isothermal titration calorimetry capable of elucidating the nature of ongoing reactions from a thermodynamic point of view. The experiments were performed with a humic acid isolated by standard isolation procedure from Leonardite (1S104H) purchased from the International Society for Humic Substances, with humic acids isolated from lignite as well as modal chernozem. The aim of the submited diploma thesis is to assess the influence of carboxyl functional groups in the structure of humic acids to interactions with Septonex. For this reason, said samples of humic acids have been modified by selective methylation of their carboxyl functional groups, which can no longer participate in interactions with ionic substances. Results from diffusion cells and isothermal titration calorimetry confirmed the assumption that Septonex interacted with all types of unmodified humic acids more than with their methylated derivatives. Despite the available literature, it was surprising that the differences in the interaction of humic acids with Septonex were not diametrically different when comparing unmodified humic acids with their methylated derivatives. The extent of these interactions was assessed through the apparent equilibrium constant Kapp determined in the diffusion (dialysis) experiments and from the course of enthalpy curves from isothermal titration calorimetry. After the experiments and their evaluation, it can be concluded that humic acids and Septonex in their interactions, due to their structures, probably apply not only electrostatic interactions, especially through available carboxyl functional groups of humic acids and positively charged hydrophilic parts of Septonex molecules, but also a significant role have a hydrophobic effect, hydrogen bonds and Van der Waals forces.

The aim of the Diploma thesis is to consider an influence of soil management (rotation of crops on arable land and grassland) to quantity and quality of humic substances. These properties are depended not only upon way of soil management, but also upon climatic effects, such are rainfall, temperature, elevation above sea-level, level of underground water and content of clay. Significantly influenced factors are content and form of organic carbon which is very tightly bonded to humic substances. In this work the humic acids content and properties progression was studied in given time period. Also the effect of crop rotations to changes of physical and chemical properties of humic acids in soil environment was observed. Diploma thesis was realized in co-operation with Mendel University in Brno, which supplied elaborating samples. Studied soil samples were taken from humus horizon Cambisol modal Vatín during years 1999–2006, always in autumn. Individual samples were characterized by available analytical methods, which are generally used in humic substances research area. They are especially fluorescence spectrometry, UV-VIS and infrared spectrometry and acid-base and conductometric titrations.