This diploma thesis is focused on the study of dissociation behaviour of natural biocolloids, namely humic acids and fulvic acids. Humic and fulvic acids are natural, heterogeneous, high molecular weight substances which behave as weakly acidic polyelectrolytes and they have complex not exactly described structure. They are formed by biochemical transformations of organic residues (mainly plants). They are part of the soil, water, peat, sediments and coal. Solubility of humic acids is affected by pH value. The higher the pH value is the higher the solubility is. Fulvic acids are soluble in whole range of pH values. The aim of this diploma thesis is to determine the dissociation constant for the five kinds of humic acids and four kinds of fulvic acids, which have been isolated from various natural sources. These samples were purchased from IHSS. Dissociation constants were determined by the conductometric method and a combination of measurment pH and the content of acidic functional groups in Na2SO4. UV-VIS spectrophotometry method was used to characterize the quality of humic acids and fulvic acids.

This diploma thesis deals with the study of non-stationary diffusion of cupric ions in humic gels. The main objective of the work was the optimalization of conditions for using the electrochemical analyzer EcaFlow 150 GLP for the study of diffusion experiments. Next part was focused on reaching of constant concentration profiles of cupric ions in humic gel. Last aim of the study was the bond strength between cupric ions and humic acids. Diffusion was characterized by the values of the diffusion flux and cupric ions concentration profiles in humic gel. The data necessary for calculation were obtained by the electrochemical analyses of the extracts of each slice after diffusion on the EcaFlow 150 GLP. It has been proved that after application of several adjustment is this method suitable for the study of diffusion experiments. By using of different extraction agents was obtained the fractionalization of cupric ions according to the bond strength to humic acids.

The diploma thesis focuses on utilization of diffusion cells in reactivity mapping study on humic acids. In the experimental part, samples 6 humic acids of different origin or chemical modification were studied. All the samples were characterized by basic analytical and physico-chemical methods (elemental analysis, thermogravimetry, determination of acidity, spectrometry). Methylene blue was utilized as a model reactive probe and agarose gel as an inert support medium. An effect of interactions between humic acids and methylene blue on diffusivity of the dye in the hydrogel was determined and discussed.

The behaviour of humic acids in aqueous solutions is closely connected to the content of acid functional groups and their dissociation abilities. The titration methods are the most often used for the research of acid-base characteristics of humic acids, their results should lead to the determination of the content of functional groups and their pKa. However the determined values depend on many factors including the titration speed. The spectrophotometric determination of dissociation constant was used in this diploma thesis. Reliability of this method was confirmed in bachelor thesis where is mentioned that spectrophotometric determination of pKa corresponds with realistic dissociation behaviour of humic acids in the water much more better than values obtained from titration methods. The principle of newly used spectrophotometry method is the preparation of humic acids solutions in three different media with different pH values. Acid groups of humic acids are practically completely dissociated in intensely basic environment and the measured absorbance is caused by anion of „humate“. On the contrary their dissociation in acid environment is suppressed so much that we measure the absorbance of non-dissociated molecules of humic acids. Deionized water was used like neutral solvent. Water was replaced by acetic buffer in this thesis because of water’s properties which have significant influence on solutions' pH. Buffer was used for diluting or for solubilisation and in these both cases more stable pH values were occurred. The aim of this diploma thesis is investigate UV/VIS spectra of various solutions of humic acids with different values of pH and determinate mean value of pKa of humic acids which could be used like comparison of dissociation behaviours for vary samples. Values of acid dissociation constant were determined from measured dates and compared with values obtained by titration method. The UV/VIS spectra gained in combination with the results of pH measuring and the conductivity next showed the differences in the behaviour of differently prepared samples of humic acids.

The thesis deals with a utilization of hydrogels made of humic acids in both basic and applied research of this valuable natural material. The attention is paid to an interaction between the humic gel and cupric ions as the model heavy metal. The main experimental part focuses on an optimation of simple laboratory diffusion methods which serve as an innovative tool for modeling pollutants’ transport in natural humic environments. Various techniques were used in order to determine a diffusion coefficient of cupric ions in humic gel; the value is closely linked with the studied interaction between solid content of the gel and the diffusing species. Consequently, the diffusivity can be used as a standard parameter for basic reactivity mapping studies concerning humic substances. The final chapter of the thesis deals with a preparation of mixed reversible hydrogels formed by a reaction between humic acids and chitosan. These materials represent a suitable colloidal form for humic acids’ industrial and agricultural applications.

No description available.

Einleitung: Bei Milchkühen häufen sich Erkrankungen in der Frühlaktation. Sie gehören zu den wichtigsten Ursachen frühzeitiger Merzung und damit der aktuell unbefriedigenden Nutzungsdauer. Ziele der Untersuchungen: Ziel dieser Arbeit war es, den Stoffwechsel von Milchkühen in der kritischen Übergangszeit vom Trockenstehen zur Laktation (Transitphase) durch drei verschiedene prophylaktische Maßnahmen zu stabilisieren: mittels Huminsäuren Belastungen aus dem Darm einschließlich Endotoxinen zu mindern, mit einem Ammoniumpropionat-Propylenglykol- Gemisch die Energieversorgung zu verbessern sowie mit Dexamethason-21-isonicotinat die Stoffwechselfunktion der Leber zu fördern sowie gleichzeitig Entzündungsprozesse infolge der Kalbung zu hemmen. Materialien und Methoden: Die Untersuchungen wurden in einem sächsischen Bestand an 312 Kühen der Rasse „Holstein Friesian“ randomisiert innerhalb eines Jahres durchgeführt. An jeweils 78 Kühe wurden 300 ml Ammoniumpropionat-Propylenglykol-Gemisch(C3) täglich vom 14. Tag ante partum (a.p.) bis zum 14. Tag post partum (p.p.) oral verabreicht; ebenfalls oral wurden 100 g Huminsäure-Fertigpräparat (HS-FP) bzw. 50 g Huminsäuren-Rohstoff (HS-RS) im selben Zeitraum appliziert, und Dexamethason-21-isonicotinat (DEXA21) wurde einmalig am 1. Tag p.p. intramuskulär in der Dosierung 0,02 mg/kg Körpermasse verabreicht. 78 unbehandelte Kühe dienten als Kontrollgruppe. Die Auswirkungen dieser Maßnahmen auf Gesundheit, Leistung und Stoffwechsel wurden durch klinische Untersuchungen, durch Blutkontrollen am 14. Tag a.p., am 3. und 28. Tag p.p. (Leukozyten, freie Fettsäuren [FFS], Bilirubin, ß-0H-Butyrat[BHB], Glucose, Cholesterol, Creatinkinase [CK], Aspartat-Amino-Transferase [ASAT], Glutamat-Dehydrogenase [GLDH], gamma-Glutaryl-Transferase [GGT], Protein, Albumin, Mg, Fe, Ca, anorganisches Phosphat [Pi], Na, K) sowie durch die Erfassung von Gesundheitsstatus, Milchleistung und Fruchtbarkeit zu bestimmten Zeitpunkten geprüft. Ergebnisse: Die verschiedenen prophylaktischen Maßnahmen hatten keinen signifikanten Einfluss auf Fruchtbarkeits- und Gesundheitsparameter. Bei den absoluten und fettkorrigierten Milchmengen konnten ebenfalls keine statistisch gesicherten Unterschiede zwischen den Versuchsgruppen und der Kontrollgruppe festgestellt werden. Der Milcheiweißgehalt von C3 28 d p.p. sowie der Milchfettgehalt von DEXA21 und C3 100 d p.p. waren signifikant erhöht. Die Ergebnisse der Blutuntersuchungen ergaben hauptsächlich am 3., aber auch am 28. Tag p.p. gesicherte Unterschiede bei wichtigen Stoffwechselparametern wie Glucose, Cholesterol, Bilirubin, Protein, Albumin, Ca, Fe und CK. Die einmalige Gabe von Dexamethason-21-isonicotinat am 1. Tag p.p. hatte den besten Einfluss auf den Leber- und Energiestoffwechsel. In dieser Gruppe waren am 3. Tag p.p. die Glucose-, Bilirubin-, Cholesterol-, Protein, Ca- und Fe-Konzentrationen sowohl gegenüber der KG wie auch gegenüber allen anderen Versuchsgruppen signifikant günstiger. Für die Albumin- und Na-Konzentrationen sowie die CK-Aktivität traf das gegenüber der Kontroll- sowie der C3-Gruppe zu. Der Einsatz der Wirkstoffe mit HS-RS, HS-FP sowie C3 führte ebenfalls zu positiven Effekten auf die Leistung und den Stoffwechsel gegenüber der Kontrollgruppe, jedoch ließen sich diese nur in wenigen Fällen statistisch sichern. Schlussfolgerungen: Die Applikation von Dexamethason-21-isonicotinat einen Tag p.p. stabilisiert signifikant den Stoffwechsel von Kühen nach dem Partus. Gleichartige Effekte auf Milch- und Fruchtbarkeitsleitung sowie die Morbidität konnten nicht gesichert nachgewiesen werden. Für Huminsäure-Rohstoff, Huminsäure-Fertigpräparat sowie Ammoniumpropionat-Propylenglykol-Gemisch waren solche Effekte tendenziell erkennbar, statistisch aber nicht zu sichern. Auch wenn besonders mit Dexamethason-21-isonicotinat der Stoffwechsel in Belastungssituationen kurzfristig stabilisiert werden kann, müssen generell Haltung und Fütterung analysiert sowie Mängel beseitigt werden. / Problem: In dairy cattle diseases are common in early lactation. They are among the main causes of early culling and the current unsatisfactory productive life. Objective: The aim of this work was to stabilize metabolism of dairy cows in the critical transition period from standing dry to lactation by three different prophylactic applications: using humic acids to minimize strain from the gut including endotoxins, using ammonium propionate mixed with propylene glycol to improve energy supply and dexamethasone-21-isonicotinate to promote metabolic function of the liver and at the same time to inhibit inflammatory processes following parturition. Experimental design: The studies were performed in a Saxon dairy farm on 312 cows of the „Holstein Friesian\" breed, randomly performed within one year. 78 cows were administered orally 300 ml ammonium propionate mixed with propylene glycol (C3) daily from 14 days before parturition (a.p.) to 14 days after parturition (p.p.), another 78 cows 100 g of a humic acid drug (HS-FP) or 50 g of humic acid raw material (HS-RS) were administered orally in the same period and dexamethasone-21-isonicotinate (DEXA21) was applied intramuscularly to another 78 cows on the first day p.p. in a dose of 0.02 mg/kg body weight. 78 untreated cows were used as control group. The impact of these administrations on health, performance and metabolism has been measured by clinical examinations and blood tests on 14. day a.p., on 3. and 28. day p.p. (Leukocytes, free fatty acids [ FFS ], bilirubin, beta-0H-butyrate [BHB] , glucose, cholesterol, creatine kinase [CK], aspartate aminotransferase [AST], glutamate dehydrogenase [GLDH], gamma glutaryl transferase [GGT], protein, albumin, Mg, Fe, Ca, inorganic phosphate [Pi] , Na, K) and was verified by detection of health status, milk yield and fertility. Results: The different prophylactic administrations had no significant effect on fertility and health parameters. The absolute and fat- corrected milk yields also showed no statistically reliable differences between experimental groups and control group. Milk protein content in C3 28 days p.p. and milk fat content in DEXA21 and C3 100 days p.p. were significantly increased. Blood control results showed mainly on 3. and 28. day p.p. important differences in metabolic parameters, such as glucose, cholesterol, bilirubin, protein, albumin, Ca, Fe and CK, which are statistically secured. A single dose of dexamethasone-21- isonicotinate on first day p.p. had the best effect on liver and energy metabolism. Three days p.p. glucose, bilirubin, cholesterol, protein, Ca and Fe concentrations performed significantly better in DEXA21 group compared both to control group and all other treatment groups. For albumin and Na concentrations and CK activity that was true with respect to control and C3 group. The use of a humic acid drug, humic acid raw material and ammonium propionate mixed with propylene glycol had positive impact on performance and metabolism compared with control group too, but could be statistically secured in only a few cases. Conclusions: The application of dexamethasone-21-isonicotinate at the first day p.p. significantly stabilizes metabolism in cows after parturition. Similar effects on milk yield and fertility as well as morbidity could not be observed. For humic acid drug, humic acid raw material and ammonium propionate mixed with propylene glycol such effects tended to be recognizable, but cannot be statistically secured. Metabolism can be stabilized in short term stress situations with dexamethasone-21-isonicotinate, general care and feeding must be analyzed and deficiencies have to be eliminated.

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 Jorge Silva (jorgelmsilva@ufrrj.br) on 2016-10-19T19:18:40Z No. of bitstreams: 1 2015 - Jo?o Ant?nio Montibeller Furtado e Silva.pdf: 2711514 bytes, checksum: effd09162dc88c6c073a5293a03578ff (MD5) / Made available in DSpace on 2016-10-19T19:18:40Z (GMT). No. of bitstreams: 1 2015 - Jo?o Ant?nio Montibeller Furtado e Silva.pdf: 2711514 bytes, checksum: effd09162dc88c6c073a5293a03578ff (MD5) Previous issue date: 2015-08-26 / CAPES / FAPERJ / In the zones that produce swine, the farms have a high concentration of animals that generate large amounts of slurry, which becomes a problem due to lack of agricultural area for distribution, at the rates calculated to be used as a supply of nutrients to crops. Systematic application of pig slurry (PS) can increase the levels of heavy metals (HMs) in the soil. The HMs dynamics in the soil depends on their chemical form, the slurry characteristics, plant absorption capacity and the phytomass management. The purpose of this study was to study the effect of applying PS fertilizing and intensity of nutrient removal, represented by managements of biomass, in the dynamics of soil HMs. The levels of heavy metals (Cu, Zn, Mn, Ni and Pb) were evaluated in a area with Typic Hapludox soil, after three applications of PS. The Humic Acid (HA) obtained from PS samples was characterized in terms of elemental composition, nuclear magnetic resonance of carbon-13 and infrared spectroscopy, in order to evaluate their potential to interact with the HMs. The total contents of Cu, Zn, Mn, Ni and Pb was determined in feed samples, PS from slurry tanks on a finishing swine farm and plants fertilized with PS, consisting a consortium of lopsided oat (Avena strigose, Schreb.) and Italian rye grass (Lolium multiflorum Lam.). The dynamics of HMs in soil was assessed by determining the pseudototals levels in six layers (0-2.5; 2.5-5; 5-10; 10-20; 20-40; 40-80 cm), and bioavailable in the layer of most exploration of consortium roots studied (0-20 cm). The metals Cu, Zn, Mn, Ni e Pb were found in the feed, indicating the source and origin of the HMs in the PS. With 55% of aliphatic chains, 14% of oxygenated aliphatics and 15% of carboxyl, the characterization of HA in the PS showed a high capacity to interact and form soluble complexes with HMs. All analysed HMs had pseudototals levels that increased in all six layers of soil, as a function of the PS dose applied, and the bioavailable forms in the arable layer (0-20 cm). The management with higher intensity of biomass removal, the soil showed the lowest levels of HMs, pseudototal and bioavailables. The total metal accumulation in plants showed a positive and significant correlation with the levels of bioavailables in the soil, suggesting that the HMs were in exchangeable and/or hydrosoluble forms, capable of being transferred to water bodies and to enter the food chain. / Nas regi?es produtoras de su?nos, as granjas apresentam elevadas concentra??es de animais que geram grandes quantidades de res?duos, tornando-se um problema devido ? falta de ?rea agr?cola para sua distribui??o, em taxas calculadas para o fornecimento de nutrientes para as culturas.Aplica??es sistem?ticas de dejeto l?quido de su?nos (DLS) podem elevar os teores de metais pesados (MPs) no solo. A din?mica dos MPs depende da forma qu?mica que se encontram no solo, das caracter?sticas do res?duo aplicado, da absor??o pelas plantas e do manejo da fitomassa. Com o objetivo de estudar os efeitos da aplica??o de dejeto l?quido de su?nos e da intensidade de remo??o de nutrientes, representadas por manejos de fitomassa, na din?mica de MPs do solo, o presente trabalho avaliou os teores de metais pesados (Cu, Zn, Mn, Ni e Pb) em uma ?rea de Nitossolo Vermelho Distr?fico, ap?s tr?s aplica??es de DLS.Os ?cidos h?micos (AH) obtidos de amostras de DLS foram caracterizados quanto ? composi??o elementar,resson?ncia magn?tica nuclear do carbono-13 e espectroscopia de infravermelho, a fim de se avaliar o seu potencial de intera??o com os MPs. Foram determinados os teores totais de Cu, Zn, Mn, Ni ePb em amostras de ra??o, DLS oriundo de esterqueiras, e em tecido do cons?rcio de plantas de aveia preta (Avena strigosa Schreb.) e azev?m (Lolium multiflorum Lam.) adubadas com DLS. A din?mica dos MPs no solo foi avaliada atrav?s da determina??o dos teores pseudototais em seis camadas do solo (0-2,5; 2,5-5; 5-10; 10-20; 20-40, e 40-80 cm), e biodispon?veis na camada de maior explora??o das ra?zes do cons?rcio estudado (0-20 cm).Os metais Cu, Zn, Mn, Ni e Pb foram encontrados na ra??o, indicando a origem desses MPs no DLS. A caracteriza??o dos AH do DLS, com 55% de cadeias alif?ticas, 14% alif?ticas oxigenadas e 15% de carboxilas, demonstra a sua alta capacidade de intera??o e forma??o de complexos sol?veis com MPs. Todos os metais avaliados apresentaram ac?mulo nas seis camadas do solo em fun??o da dose de DLS aplicada, inclusive em formas biodispon?veis na camada ar?vel (0-20 cm). No manejo com maior intensidade de remo??o de fitomassa, o solo apresentou os menores teores de MPs, tanto pseudototais, como biodispon?veis. O ac?mulo total desses metais nas plantas apresentou correla??o positiva e significativa com os teores biodispon?veis do solo, indicando que os MPs se encontravam em formas troc?veis e/ou hidrossol?veis, com capacidade para serem transferidos para corpos h?dricos e entrar na cadeia tr?fica.

Objective of this project was the study of interaction processes between humic substances, U(VI), Np(V) and kaolinite KGa-1b. It contributed to the attainment of a better process understanding, the improvement of the knowledge on the interaction of humic substances and metal ions and the enhancement of the thermodynamic database. With a synthetic humic acid (HA), N-containing functional groups of HA were characterized by 15N-NMR spectroscopy. Based on these results, model studies of the influence of amino groups on the complexation behavior of HA were performed. Spectroscopic studies with amino acids show that the amino group do not contribute to the U(VI) complexation at pH 4. The impact of kaolinite on the formation of HA and humic substance-kaolinite-sorbates was studied in model syntheses. The results exhibit that the presence of kaolinite during the syntheses mainly influences the yields on HA and their elemental compositions. Synthetic humic substance-kaolinite-sorbates were isolated. Under exclusion of CO2, the U(VI) complexation by HA was investigated at pH 7 by means of the conventional time-resolved laser-induced fluorescence spectroscopy (TRLFS) and TRLFS with ultrafast pulses. Complexation parameters for the ternary complex UO2(OH)HA(I) were determined. Studies of the Np(V) reduction in presence of HA with different functionalities under anaerobic conditions have shown that Np(V) is reduced to Np(IV) by HA. The redox capacity depends on the HA functionality. Applying a modified HA it was verified that phenolic/acidic OH groups play a dominating role in the Np(V) reduction. The influence of HA on the U(VI) and Np(V) sorption onto kaolinite was investigated in batch experiments. In dependence on the experimental conditions, HA effects the sorption and consequently the mobility of U(VI) and Np(V). From studies of the U(VI) sorption onto synthetic humic substance-kaolinite-sorbates it was concluded that the structure and functionality of sorbed/associated humic substances considerably influence the sorption behavior of U(VI). The structure of U(VI)-kaolinite-surface complexes in presence of HA was studied by means of X-ray absorption spectroscopy and TRLFS and compared to those of U(VI)-kaolinite-complexes. Investigations of the migration of HA and U(VI) in the laboratory system kaolinite-water were carried out in diffusion experiments. The migration of HA in compacted clay is governed by diffusion and influenced by its colloidal properties. Humic substances exert an immobilizing effect on the U(VI) transport in compacted kaolinite.