Submitted by Simone Souza (simonecgsouza@hotmail.com) on 2017-11-01T13:29:41Z No. of bitstreams: 1 DISS_2014_Marcelo Ribeiro Vilela Prado.pdf: 1150988 bytes, checksum: 36eb92875df21fe3c45acb2e087fd577 (MD5) / Approved for entry into archive by Jordan (jordanbiblio@gmail.com) on 2017-11-08T15:21:06Z (GMT) No. of bitstreams: 1 DISS_2014_Marcelo Ribeiro Vilela Prado.pdf: 1150988 bytes, checksum: 36eb92875df21fe3c45acb2e087fd577 (MD5) / Made available in DSpace on 2017-11-08T15:21:06Z (GMT). No. of bitstreams: 1 DISS_2014_Marcelo Ribeiro Vilela Prado.pdf: 1150988 bytes, checksum: 36eb92875df21fe3c45acb2e087fd577 (MD5) Previous issue date: 2014-04-25 / As substâncias húmicas são compostos orgânicos encontrados em sedimentos, solos, água e resíduos. Têm efeitos positivos sobre a fisiologia e crescimento das plantas e melhoram os atributos químicos, físicos e biológicos do solo. Nos últimos anos tem surgido no mercado inúmeros fertilizantes orgânicos, condicionadores de solo e bioestimuladores contendo essas substâncias. Porém, são escassos os estudos científicos que comprovem os benefícios do uso agrícola desses produtos. O objetivo deste trabalho foi avaliar os efeitos de um fertilizante organomineral enriquecido com substâncias húmicas no cultivo de soja submetida a estresse hídrico. Em casa telada foram realizados dois experimentos simultâneos, um em solo de textura média e outro em arenosa. Os solos foram corrigidos a um nível de fertilidade adequado e as condições de umidade do solo adotadas foram 90% da capacidade da capacidade de retenção de agua para as plantas cultivadas sem estresse e 30% para as cultivadas com estresse hídrico. O delineamento foi em blocos casualizados, esquema fatorial 2x5 (duas umidades e cinco doses: 0; 1; 2; 4 e 8 mL dm-3), totalizando 10 tratamentos para cada textura de solo, com oito repetições. O fertilizante organomineral foi aplicado ao solo 21 dias após a emergência das plantas e uma semana após sua aplicação estabeleceram-se os regimes de umidade. Avaliaram-se altura das plantas, massa seca da parte aérea e massa seca das raízes no florescimento e colheita da cultura, produtividade de grãos e teores foliares de macro e micronutrientes. Em nenhum dos solos o fertilizante organomineral foi capaz de atenuar os efeitos do estresse hídrico, resultando na queda da produtividade dos grãos de soja em mais de 50% quando comparado às plantas cultivadas sem estresse hídrico. Houve resposta positiva a doses para os parâmetros avaliados, sendo que, na condição de estresse hídrico, as doses mais eficientes do fertilizante organomineral foram 5,5 e 6,5 mL dm-3 para os solos textura média e arenosa, respectivamente; houve menor concentração foliar de N, P e K nas plantas com estresse e maior concentração de S; as substâncias húmicas favorecem a absorção de micronutrientes, independente da condição de cultivo. O estresse hídrico adotado foi muito severo. / Humic substances are organic compounds found in sediments, soils, water and waste materials. They have positive effects on the physiology and growth of plants and improve the chemical, physical and biological attributes of the soil. In recent years, many new organic fertilizers, soil conditioners and biostimulators containing these substances have been launched in the market. However, there have been very few scientific studies proving the benefits of agricultural use of these products. The objective of this work was to assess the effects of an organomineral fertilizer enriched with humic substances on soybeans submitted to water stress. Two simultaneous experiments were carried out in a greenhouse, one in soil with medium texture and the other in a sandy soil. The soils were corrected to a suitable fertility level and the soil moisture conditions were 90% of the water retention capacity for plants grown without stress and 30% for those cultivated with stress (considered a very severe stress level). The experimental design was randomized blocks in a 2x5 factorial scheme (two moisture levels and five fertilizer doses: 0, 1, 2, 4 and 8 mL dm-3), for a total of 10 treatments for each soil texture, with eight repetitions. The organomineral fertilizer was applied in the soil 21 days after emergence of the plants, and the moisture regimes were established one week later. The parameters measured were plant height, dry mass of aerial parts and of roots (at flowering and harvest), grain yield and leaf concentrations of macro and micronutrients. The organomineral fertilizer was unable to attenuate the effects of water stress on grain yield in either of the soils: the yield declined by more than 50% in the stressed plants in both soils. There was a positive response to fertilizer doses for the other parameters measured. Under water stress, the most efficient doses were 5.5 and 6.5 mL dm-3 in the soils with medium and sandy textures, respectively. There were lower leaf concentrations of N, P and K in the stressed plants and a higher concentration of S. The humic substances favored the uptake of micronutrients, irrespective of the growing condition.

Submitted by Geyciane Santos (geyciane_thamires@hotmail.com) on 2015-10-21T13:33:55Z No. of bitstreams: 1 Dissertação - Keila Cristina Pereira Aniceto.pdf: 13233351 bytes, checksum: a596ab3a5aae9203710f9defe415a7bf (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-10-21T19:47:17Z (GMT) No. of bitstreams: 1 Dissertação - Keila Cristina Pereira Aniceto.pdf: 13233351 bytes, checksum: a596ab3a5aae9203710f9defe415a7bf (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-10-22T12:49:54Z (GMT) No. of bitstreams: 1 Dissertação - Keila Cristina Pereira Aniceto.pdf: 13233351 bytes, checksum: a596ab3a5aae9203710f9defe415a7bf (MD5) / Made available in DSpace on 2015-10-22T12:49:54Z (GMT). No. of bitstreams: 1 Dissertação - Keila Cristina Pereira Aniceto.pdf: 13233351 bytes, checksum: a596ab3a5aae9203710f9defe415a7bf (MD5) Previous issue date: 2008-11-26 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The way the item is associated with the soil is decisive for its bioavailability . Several attributes are relevant in your the partition geochemistry, among them, the mineralogical composition, organic matter content and pH. Aiming to evaluate the potential of retaining elements in the solid portion of the material accumulated in urban areas in Manaus were selected two areas, the Garden City and the district of the Novo Israel where are located old landfills in the city. We collected 52 samples corresponding to three profiles, one in each place and a third for a natural soil. Were determined by X-ray diffraction (XRD) mineralogical composition, pH in water and KCl, the percentage of organic matter, characterization of the humic acids by infrared spectrometry and chemical speciation of the elements by sequential extraction of Zn, Cu, Pb, Ni, Cr, Mn, Fe, Cd, Ca, Mg, Na and K. The elements associated with water-soluble fraction, exchangeable, amorphous, organic matter, oxy-hydroxides of residual Fe and were quantified by atomic absorption spectroscopy. The results show pH acid in Natural soil (4.2-4.7) and more alkaline in the material accumulated on the old landfills (6.2-7.6). These values indicate reversal in the net charge of the material from negative to positive in 100% of the samples of the Novo Israel and 50% of Garden City. The percentage of organic matter that is higher in the material accumulated (8%) than in the natural soil (2%), is compatible with of functionals groups of alcohols phenols or carboxylic acids, as well as, compounds aliphatic, aromatic and amides, , that indicate the presence of humic substances. The mineralogical analysis show up the predominance of kaolinite and traces of oxy-hydroxides of Fe. The sequential extraction showed that the majority of the items have preference for the residual fraction, however, the amorphous fractions, organic matter, oxy-hydroxides of Fe, also contribute to the setting of the elements. Only Ni, Cr and Cd in Garden City, and Cr and Cd in Novo Israel are restricted to the residual fraction, which means they are more stable and with less contamination in the material studied. The Zn, Mn, Ca, Mg and K are more content in soluble fractions and exchangeable and are more bioavailability to the contamination of groundwater, plants and animals. For the material naturally, there was enrichment for most elements, in both the Garden City (Zn, Cu, Pb, Mg and K) as the Novo Isral (Zn, Cu, Pb, Cr, Mn, Cd, Ca, Mg and K). / A forma como o elemento está associado ao solo é determinante para sua biodisponiblidade. Vários atributos são relevantes na sua partição geoquímica, entre eles, a composição mineralógica, teor de matéria orgânica e pH. Com o objetivo de avaliar o potencial de retenção dos elementos na porção sólida do material acumulado em áreas urbanas de Manaus foram selecionadas duas áreas, o Horto Municipal e o bairro de Novo Israel, ondese localizam antigos lixões da cidade. Foram coletadas 52 amostras correspondentes a três perfis, um em cada local e um terceiro correspondente a um solo natural. Foram determinadas a composição mineralógica por difratometria de raios-x (DRX), pH em água e KCl, percentual de matéria orgânica, caracterização dos ácidos húmicos por espectrometria de infravermelho e especiação química dos elementos por extração seqüencial de Zn, Cu, Pb, Ni, Cr, Mn, Fe, Cd, Ca, Mg, Na e K. Os elementos associados à fração solúvel em água, trocável, amorfos, matéria orgânica, óxi-hidróxidos de Fe e residual foram quantificados por espectroscopia de absorção atômica. Os resultados mostram pH ácido no solo natural (4,2-4,7) e alcalino no material acumulado nos antigos lixões (6,2-7,6). O pH mostra inversão na carga líquida do material de negativo para positivo em 100% das amostras do Novo Israel e em 50% do Horto Municipal. O percentual de matéria orgânica que é mais elevada no material acumulado (8%) que no solo natural (2%), é compatível com a presença de grupos funcionais de álcoois, fenóis ou ácidos carboxílicos, bem como, de compostos alifáticos, aromáticos e amidas, que indicam a presença de substâncias húmicas. As análises mineralógicas evidenciam a predominância de caulinita e traços de oxi-hidróxidos de Fe. A extração sequencial mostrou que a maioria dos elementos ocorrem na fração residual, porém, as frações amorfo, matéria orgânica, óxi-hidróxidos de Fe, também contribuem para a fixação dos elementos. Apenas Ni, Cr e Cd, no Horto Municipal e Cr e Cd em Novo Israel estão restritos à fração residual, o que significa que são os mais imóveis e com menor grau de contaminação no material estudado. O Zn, Mn, Ca, Mg e K têm maior conteúdo nas frações solúvel e trocável e são mais biodisponíveis para a contaminação das águas subterrâneas, plantas e animais. Em relação ao material natural, houve enriquecimento para a maioria dos elementos tanto no Horto Municipal (Zn, Cu, Pb, Mg e K) quanto em Novo Israel (Zn, Cu, Pb, Cr, Mn, Cd, Ca Mg e K).

Submitted by Cássia Santos (cassia.bcufg@gmail.com) on 2016-10-05T10:29:36Z No. of bitstreams: 2 Dissertação - Lucas Morais Lôbo - 2015.pdf: 1058045 bytes, checksum: 36335f32e71fcf45a95a64517ccd5f37 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-10-05T10:59:13Z (GMT) No. of bitstreams: 2 Dissertação - Lucas Morais Lôbo - 2015.pdf: 1058045 bytes, checksum: 36335f32e71fcf45a95a64517ccd5f37 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-10-05T10:59:13Z (GMT). No. of bitstreams: 2 Dissertação - Lucas Morais Lôbo - 2015.pdf: 1058045 bytes, checksum: 36335f32e71fcf45a95a64517ccd5f37 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2015-03-31 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Processes of phosphorus adsorption in soil diminish the availability of this nutrient to plants. Humic and fulvic acids present in humic substances (SH) can block the phosphorus adsorption sites in the soil. Thus, this study aimed to verify the effect of adding doses of a SH, availability of P in two types of soils with different adsorption capacities. The treatments consist of four levels of SH (0, 100, 200 and 400 kg.ha-1), two phosphorus sources (Triple superphosphate – SFT and Natural Reactive phosphate – FNR), and three assessment time (7, 14 and 28 days) in two soil types (Red Latosol – LV and Quartzipsamment – NQ). The application of SH altered the availability of P in different soils. Statistical analysis of the data showed a significant difference (P<0,05) for all factors. In LV the P availability increased for both sources, with increasing SH dose up to 14 days. At 28 days the P-available decreases, with no significant difference between doses, but remains superior to treatment without addition of SH. In the NQ the P-available decreases from the addition of the doses of 200 and 400 kg ha-1 of SH up to 14 days of incubation. After 28 days with the degradation of SH values of P-available for these doses begin to increase. These results indicate that the use of SH is effective in increasing the availability of phosphorus in different soils. / Os processos de adsorção de fósforo (P) no solo diminuem a disponibilidade deste nutriente para as plantas. Os ácidos húmicos e fúlvicos presentes nas substâncias húmicas (SH) podem bloquear os sítios de adsorção de fósforo no solo. Desta forma, este estudo teve como objetivo verificar o efeito da adição de doses de SH, na disponibilidade de P em dois tipos de solos com diferentes capacidades de adsorção. Os tratamentos são constituídos de quatro doses de SH (0, 100, 200 e 400 kg ha-1), duas fontes de fósforo (Superfosfato triplo – SFT e Fosfato Natural Reativo – FNR), e três épocas de avaliações (7, 14 e 28 dias), em dois tipos de solos (Latossolo Vermelho – LV e Neossolo Quartzarênico – NQ). A aplicação de SH alterou a disponibilidade de P nos diferentes solos. A análise estatística dos dados mostrou que houve diferença significativa (P<0,05) para todos os fatores. No LV a disponibilidade de P aumentou, para ambas as fontes, com o aumento da dose de SH até aos 14 dias. Aos 28 dias o P-disponível diminui, não havendo diferença significativa entre as doses, porém permanece superior ao tratamento sem adição de SH. No NQ o P-disponível diminui a partir da adição das doses de 200 e 400 kg ha-1 de SH até aos 14 dias de incubação. Aos 28 dias com a degradação da SH os valores de P-disponível para estas doses começam a aumentar. Estes resultados indicam que a utilização de SH é eficiente no aumento da disponibilidade de P em diferentes solos.

No description available.

No description available.

The objective of this research was to investigate lead speciation in the soil/sediment-water environment and to better understand how the species affect lead mobility under different environmental conditions. The research involved both field soil and sediment samples as well as standard lead solutions. Field samples were fully characterized and extracted by aqueous and organic solvents. The results were compared and evaluated with the metal speciation model, MINTEQA2. Hydrolytic polymerization and organic complexation studies were conducted with standard lead solutions under controlled experimental conditions. Results of the field samples showed that pH, dissolved cations, ionic strength, dissolved organic matter, and nature of the soil/sediment matrix play major roles in the distribution and mobility of lead (Pb) from contaminated sites. In the aqueous equilibration experiment, the magnitude of Pb2+ solubilization was in the order of pH4>pH7>pH9. The results were in good agreement with MINTEQA2 predictions. An important finding of the research is the detection of Pb polymerization species under controlled experimental conditions. At pH 5.22, Pb polymeric species were formed at rate of 0.03 per day. The role of Pb complexation with organic matter was evaluated in both field and standard samples. Different methodologies showed three types of organically bound Pb. A very small fraction of Pb, in the ppb range, was extractable from the contaminated soil by polar organic solvents. Sequential extractions show that 16.6±1.4 % of the Pb is organically complexed. Complexation of Pb with fulvic acid provided new information on the extent of Pb association with soluble organic matter. The overall results of this research have provided new and useful information regarding Pb speciation in environmental samples. The results, in several instances, have provided verification of MINTEQA2 model's prediction. They also revealed areas of disagreement between the models prediction and the experimental results. A positive note regarding the experimental work done in the research is the verification of the mass balance in all the repeated experiments.

Os solos têm um importante papel na maioria das atividades que ocorrem no planeta, dentre as quais, destaca-se a sua participação nos principais ciclos biogeoquímicos. A matéria orgânica do solo (MOS) tem um papel primordial na sustentabilidade ambiental, pois está relacionada com a ciclagem de carbono e nutrientes, sendo assim uma figura chave tanto para estudos relacionados com mudanças climáticas globais, quanto para estudos agronômicos. Um dos principais fluoróforos da MOS são as substâncias húmicas (SH), as quais são fracionadas de acordo com a sua solubilidade em ácidos húmicos (AH), ácidos fúlvicos (FA) e humina (HU). O estudo das propriedades ópticas da matéria orgânica é uma importante ferramenta para a compreensão estrutural e molecular das frações húmicas. Frente ao exposto, esse trabalho teve com objetivo estudar a gêneses de Espodossolos Amazônicos através da avaliação das características estruturais da matéria orgânica e suas propriedades de complexação com metais empregando diversas técnicas espectroscópicas. Os resultados mostraram grandes acúmulos de carbono em profundidade e que a Matéria Orgânica nesses Espodossolos Amazônico é constituída de quatro grupos: - mais recalcitrante, humificada e antiga; - lábil e jovem; - recalcitrante, pouco humificada e antiga; - humificada e jovem. Claramente o trabalho mostrou que o processo de humificação não tem relação direta com a datação do material orgânico, e que fatores como textura, presença de água e microorganismos influenciaram nos processos de formação e humificação desse material orgânico. Por fim, a fração AF do solo parece ter uma contribuição oriunda de lençóis freáticos, sua estrutura química varia pouco no perfil e possui seletividade na interação com os metais presentes nesses solos. Basicamente, o AF tem alta afinidade de complexação com Al. A fração AH, entretanto, mostrou-se menos seletiva, associando-se com vários tipos de metais, como K, Fe, Mg, Zn e Al; e sua estrutura química varia bastante no perfil do solo. Em função da diversidade de metais associados ao AH, ele deve ser o principal responsável pela fertilidade do solo. Desta forma, os resultados mostraram que as três frações húmicas estão envolvidas no processo de podzolização do solo, e que o AF tem papel predominante no transporte de Al e o AH é o responsável no transporte do Fe. / Soils play an important role in most of the activities that occur on the planet. It participation in the main biogeochemical cycles can be highlighted. Soil organic matter (SOM) plays a key role in environmental sustainability, since it is related to carbon and nutrient cycling, being essential for studies related to global climate change and agronomy. One of the major SOM fluorophore is the humic substances (HS), which is fractionated according to their solubility in humic acids (HA), fulvic acids (FA) and humin (HU). The study of the optical properties of the organic matter is an important tool for structural and molecular understanding of humic fractions. Based on that, this work aimed the study of the Amazonian Spodosols genesis through the evaluation of organic matter structural characteristics and its properties of metal complexation using different spectroscopic techniques. The main results of this research showed large carbon accumulations in depth. Furthermore, it was possible to infer how the Amazonian Spodosols organic matter is divided: - more recalcitrant, humified and old; - labile and young; - recalcitrant, little humified and old; - humified and young. The study demonstrated clearly that the humification process has no direct relationship with the organic material dating, and that factors such as texture, presence of water and microorganisms have influenced the formation and humification of that organic material. The FA fraction of the soil has a contribution from groundwater and its chemical structure varies little in depth. Additionally, FA showed selective interaction with soil metals. However, the HA fraction has been shown less selective, associate with various metal types, such as K, Fe, Mg, Zn and Al. Moreover, its chemical structure varies greatly in the soil depth. Due to the diversity of metals that the HA has affinity, it should be the main responsible of the soil fertility. After all, the results showed that all the three humic fractions are involved in the process of soil podzolization. Furthermore, the FA has a predominant role in Al transport as the HA is the responsable of Fe transport.

Os solos têm um importante papel na maioria das atividades que ocorrem no planeta, dentre as quais, destaca-se a sua participação nos principais ciclos biogeoquímicos. A matéria orgânica do solo (MOS) tem um papel primordial na sustentabilidade ambiental, pois está relacionada com a ciclagem de carbono e nutrientes, sendo assim uma figura chave tanto para estudos relacionados com mudanças climáticas globais, quanto para estudos agronômicos. Um dos principais fluoróforos da MOS são as substâncias húmicas (SH), as quais são fracionadas de acordo com a sua solubilidade em ácidos húmicos (AH), ácidos fúlvicos (FA) e humina (HU). O estudo das propriedades ópticas da matéria orgânica é uma importante ferramenta para a compreensão estrutural e molecular das frações húmicas. Frente ao exposto, esse trabalho teve com objetivo estudar a gêneses de Espodossolos Amazônicos através da avaliação das características estruturais da matéria orgânica e suas propriedades de complexação com metais empregando diversas técnicas espectroscópicas. Os resultados mostraram grandes acúmulos de carbono em profundidade e que a Matéria Orgânica nesses Espodossolos Amazônico é constituída de quatro grupos: - mais recalcitrante, humificada e antiga; - lábil e jovem; - recalcitrante, pouco humificada e antiga; - humificada e jovem. Claramente o trabalho mostrou que o processo de humificação não tem relação direta com a datação do material orgânico, e que fatores como textura, presença de água e microorganismos influenciaram nos processos de formação e humificação desse material orgânico. Por fim, a fração AF do solo parece ter uma contribuição oriunda de lençóis freáticos, sua estrutura química varia pouco no perfil e possui seletividade na interação com os metais presentes nesses solos. Basicamente, o AF tem alta afinidade de complexação com Al. A fração AH, entretanto, mostrou-se menos seletiva, associando-se com vários tipos de metais, como K, Fe, Mg, Zn e Al; e sua estrutura química varia bastante no perfil do solo. Em função da diversidade de metais associados ao AH, ele deve ser o principal responsável pela fertilidade do solo. Desta forma, os resultados mostraram que as três frações húmicas estão envolvidas no processo de podzolização do solo, e que o AF tem papel predominante no transporte de Al e o AH é o responsável no transporte do Fe. / Soils play an important role in most of the activities that occur on the planet. It participation in the main biogeochemical cycles can be highlighted. Soil organic matter (SOM) plays a key role in environmental sustainability, since it is related to carbon and nutrient cycling, being essential for studies related to global climate change and agronomy. One of the major SOM fluorophore is the humic substances (HS), which is fractionated according to their solubility in humic acids (HA), fulvic acids (FA) and humin (HU). The study of the optical properties of the organic matter is an important tool for structural and molecular understanding of humic fractions. Based on that, this work aimed the study of the Amazonian Spodosols genesis through the evaluation of organic matter structural characteristics and its properties of metal complexation using different spectroscopic techniques. The main results of this research showed large carbon accumulations in depth. Furthermore, it was possible to infer how the Amazonian Spodosols organic matter is divided: - more recalcitrant, humified and old; - labile and young; - recalcitrant, little humified and old; - humified and young. The study demonstrated clearly that the humification process has no direct relationship with the organic material dating, and that factors such as texture, presence of water and microorganisms have influenced the formation and humification of that organic material. The FA fraction of the soil has a contribution from groundwater and its chemical structure varies little in depth. Additionally, FA showed selective interaction with soil metals. However, the HA fraction has been shown less selective, associate with various metal types, such as K, Fe, Mg, Zn and Al. Moreover, its chemical structure varies greatly in the soil depth. Due to the diversity of metals that the HA has affinity, it should be the main responsible of the soil fertility. After all, the results showed that all the three humic fractions are involved in the process of soil podzolization. Furthermore, the FA has a predominant role in Al transport as the HA is the responsable of Fe transport.

Détermination des interactions microscopiques entre les actinides et les substances humiques présentes dans l’environnementUne quantité pondérable de plutonium a été introduite dans l’environnement lors d’essais nucléaires ou d’accidents civils. Les zones contaminées, nécessitant une surveillance particulière, sont devenues des lieux d’études très intéressants pour comprendre le comportement du plutonium dans l’environnement. Jusqu’à peu de temps encore, il était admis que le plutonium introduit dans les sols était relativement immobile en raison de sa propension à se sorber fortement sur les roches et de sa faible solubilité dans l’eau. Cependant, des études menées sur des zones contaminées montrent que les substances humiques, omniprésentes dans l’environnement, peuvent influencer la spéciation d’un métal et donc sa migration. C’est pourquoi, il est indispensable de connaître l’influence des substances humiques sur la spéciation du plutonium pour comprendre le transport de celui-ci dans un milieu naturel. Toutefois, en raison de la nature complexe et hétérogène de la matière organique naturelle, il est difficile de décrire de façon microscopique les interactions entre substances humiques et le plutonium. En effet, les substances humiques forment un mélange hétérogène de supra-molécules polydispersées produites par des réactions chimiques ou biochimiques durant la transformation naturelle de matière organique animale, végétale ou microbienne.Le but de ces travaux est d’évaluer à l’échelle de moléculaire les phénomènes de complexation des actinides par la matière organique naturelle. Ces recherches s’organisent autour de deux axes : la caractérisation de dizaines de milliers de molécules dans chaque échantillon de substances humiques naturelles et la détermination des molécules responsables de la vectorisation des actinides dans l’environnement.La mise au point d'une méthodologie a permis de mettre en évidence, pour la première fois, quelques molécules responsables de la complexation des actinides dans des échantillons de matière organique naturelle. Les résultats obtenus montrent l’influence de l’origine du prélèvement de la matière organique sur le type de molécules complexantes. Cette étude montre, également, que la vectorisation des actinides par la matière organique résulte d’une interaction avec un ensemble de molécules présentant des affinités plus ou moins forte pour le métal. Ces résultats semblent être en accord avec les modélisations macroscopiques NICA-DONNAN (approches continue) utilisés actuellement. / Large amount of plutonium has been introduced into the environment as a result of nuclear weapons testing, and nuclear power-plant accidents. Contaminated areas, which need a particular survey, have become a very interesting place to study and understand the plutonium behaviour in the environment. Until few years ago, it was admitted that plutonium introduced into subsurface environment is relatively immobile, owing to its low solubility in ground water and strong sorption onto rocks. However, studies of contaminated areas show that humic substances, which are ubiquitous in environment, can alter the speciation of metal ion, e.g. plutonium, and thus their migration. These humic substances are major components of the natural organic matter in soil and water as well as in geological organic deposits such as lake sediments, peats and brown coals. They are complex heterogeneous mixtures of polydispersed supra-molecules formed by biochemical and chemical reactions during the decay and transformation of plant and microbial remains. The knowledge of the impact of humic substances on the plutonium migration is required to assess their transport in natural systems. However, due to the complex and heterogeneous nature of humic substances, there are a lot of difficulties in the description of microscopic interactions. The aim of this PhD thesis is to evaluate as precisely as possible interactions between actinides and humic substances. This work is divided in two parts: on the one hand humic substances will be separated to identify each component, on the other hand the speciation of actinides with characterized humic substances will be studied. In the first part of this study, new methods are developed to study the speciation of actinides with humic substances using two kinds of mass spectrometers: an ICP-MS and a high resolution mass spectrometer using various ionization devices (ESI, APCI, DART, APPI) in order to determine all active molecules for the complexation.In the second part, a new way of humic substances separation had been developed using an electrophoresis capillary apparatus. This efficient separation technique allows to simplify the characterisation of the complex heterogeneous mixtures without changing speciation of the chemical system.This study will lead to point out some molecules responsible for complexation of actinides by the humic substances.

Radionuclides, 129I and 239,240Pu, are major products or by-products of nuclear fission and among the top risk drivers for waste disposal at the Savannah River Sites (SRS) and Rocky Flats Environmental Technology Sites (RFETS), respectively, due to their perceived mobility in the environment, excessive inventory, toxicity, and long half-life. The objective of this study is to investigate the role of natural organic matter in retarding or facilitating the migration of 129I and 239,240Pu in the Department of Energy (DOE) sites. Measurements of 127I and 129I in humic acids (HAs) and fulvic acids (FAs) obtained by five successive alkaline, two glycerol and one citric acid-alkaline extractions, demonstrated that these extractable humic substances (HS) together account for 54-56 percent and 46 percent of the total 127I and 129I in the soil, respectively. The variations among 127I and 129I concentrations, isotopic ratios (129I/127I), chemical properties of all these humic substances indicated iodine was bound to a small-size aromatic subunit (~10 kDa), while the large-size subunit (~90 kDa), which likely linked the small-size unit through some weak chemical forces, determined the relative mobility of iodine bound to organic matter. Soil resuspension experiments simulating surface runoff or stormflow and erosion events were conducted with soils collected from SRS. Results showed that 72-77 percent of the newly-introduced I- or IO3- were irreversibly sequestered into the organic-rich soil, while the rest was transformed into colloidal and dissolved organo-iodine by the soil. The resulting iodine remobilization contradicts the conventional view that considers only I- or IO3- as the mobile forms. Quantitative structure analysis by 13C DPMAS NMR and solution state 1H NMR on these humic substances indicate that iodine is closely related to the aromatic regions containing esterified products of phenolic and fomic acid or other aliphatic carboxylic acids, amide functionalities, quinone-like structure activated by electron-donating groups (e.g., NH2) or hemicelluloses-lignin-like complex with phenyl-glycosidic linkage. The micro-molecular environment, such as the hydrophobic aliphatic periphery hindering the active aromatic cores and the hydrophilic polysaccharides favoring its accessibility towards hydrophilic iodine species, play another key role in the interactions between iodine and SOM. NMR spectra of the colloidal organic Pu carrier which can potentially be released from the soil during the surface runoff or stormflow showed Pu was transported, at sub-pM concentrations, by a cutin-derived soil degradation products containing siderophore-like moieties and virtually all mobile Pu.