chim.anal
Aos Meus Orientadores A Professora Nádia 
  
Regina Do Nascimento E Ao Professor 
  
Stéphane Munier 
  
Dr Ao Prof 
  
Taitson Guilherme 
  
Bueno 
  
Dr Alisson Duarte Diniz 
  
Pelas Ajudas 
  
Laboratório Suely 
  
Rogério, Elaine, Sibele, Marcelo Legais Da Pós (juliana 
  
Felipe 
  
Fran Raiane 
  
Patrícia Guerra 
  
À Dra 
  
Débora Milori 
  
Prof Dra 
  
R Célia 
  
Montes 
  
Luciana E Ao Felipe 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
Keywords: Amazonie, Spectroscopique, Podzolization, Matière Organique, Pedo-paysage Amazon, Spectroscopic, Podzolization, Organic Matter, Pedo-landscape

apresenta-se: 1) um modelo de evolução pedo-geomorfológica da micro-bacia em estudo; 2) a investigação das substâncias húmicas dos solos podzolizados da bacia do Alto Rio Negro a partir da utilização dos métodos espectroscópicos

Resumo: A Amazônia é a maior floresta tropical do mundo devido principalmente a sua biodiversidade, e contribui por exemplo, para a dinâmica do clima, sequestro de carbono e regulação do ciclo de nutrientes e água em escala global. Os solos presente neste ecossistema possuem significativa participação no balanço da água e transporte de carbono. Dessa maneira, o propósito deste estudo foi compreender a distribuição dos solos em uma micro-bacia de águas escuras, o comportamento das matérias orgânicas com o foco nas frações de ácidos fúlvicos e ácidos húmicos em sistema de solos podzolizados levando em conta as características dos solos e investigar a capacidade de complexação das substâncias húmicas, com Cu 2+ e Al 3+. Para tanto foram usados métodos convencionais da pedologia e métodos espectroscópicos, de espectroscopia de absorbância uv-visível infravermelho com transformada de Fourier e fluorescência quenching e o tratamento CP/PARAFAC, para se atingir os objetivos: (i) determinar as etapas de transformação da pedopaisagem através do estudo dos solos e da distribuição espacial de solos podzolizados e gleisolos em micro-bacia de drenagem; (ii) caracterizar as substâncias húmicas e entender as regras de distribuição de ácidos fúlvicos e húmicos em sequência de espodossolos, ao longo de uma encosta, e nos horizontes ao longo dos perfis dos solos levando em consideração as características morfológicas, textura, pH, C total e variação do lençol freático; (iii) estudar a capacidade de complexação das substâncias húmicas (ácidos fúlvicos e húmicos) de amostras de solos podzóis na Bacia do Alto Rio Negro, através da identificação dos componentes fluorescentes das substâncias húmicas, da avaliação das capacidades e constantes de complexação destas substâncias com os metais Cu 2+ e Al 3+ , e da comparação com os grupos funcionais obtidos com a fluorescência de Infravermelho com transformada de Fourier (FTIR).O resultados indicam que os solos atuais da microbacia correspondem a uma segunda geração de espodossolos que estão superimpondo sobre gleisolos e que a distribuição das características dos ácidos fúlvicos e húmicos estão relacionadas a algumas das características dos solos, como a textura e a variação do lençol freático, consequentemente essa distribuição das substâncias húmicas nos solos provaca diferenças na dinâmica de complexação dos metais entre os ácidos fúlvicos e ácidos húmicos. Portanto, embora a evolução da pedo-paisagem não tenha relação direta com as características das substâncias húmicas as diferenças geoquímicas entre os ácidos fúlvicos e ácidos húmicos acompanham as transformações dos solos presentes na microbacia e são importantes para a manutenção do equilíbrio da pedo-paisagem.

Palavras-Chave: Amazônia, Espectroscopia, Podzolização, Matéria Orgânica, Pedo-paisagem.

Resumé: L'Amazonie est la plus grande forêt tropicale du monde, principalement en raison de sa biodiversité et contribue par exemple, à la dynamique du climat, séquestration du carbone et la régulation du cycle des éléments nutritifs et de l'eau à l'échelle mondiale. Les sols présents dans cet écosystème ont une participation importante à l'équilibre de l'eau et au transport du carbone. Ainsi, le but de cette étude était de comprendre la répartition des sols dans un micro-bassin d'eau sombre, le comportement des matériaux organiques en mettant l'accent sur les fractions d'acide fulvique et des acides humiques dans système podzolizé de sol en tenant compte des caractéristiques du sol et d'étudier la capacité de complexation des substances humiques avec Cu 2 + et Al 3 +. Pour cela, conséquent, nous avons utilisé des méthodes classiques de pédologique et des méthodes spectroscopiques, Infrarouge à transformèe de Fourier (FTIR), absorbance UV-visible et Fluorescence Quenching avec le traitement CP / PARAFAC pour atteindre les objectifs: (i) déterminer les étapes de traitement de pedo -paisage à travers l'étude des sols et la distribution spatiale des sols podzolisés et du gleysol dans un bassin versant (ii) caractériser substances humiques et comprendre les schémas de distribution des acides fulviens et humiques dans une séquence de sol podzols le long des profils et dans les horizons du sols en tenant compte des caractéristiques morphologiques, de la texture, du pH, carbone variation total et souterraine dans les horizons des sols d'une séquence de sols podzols; (iii) étudier la capacite de complexation des substances humiques (acides fulviques et humiques) des échantillons de sol de podzols dans le bassin du Alto Rio Negro, en identifiant les composants fluorescents des substances humiques, en évaluant les capacités et les constantes complexantes de ces substances avec les métaux Cu 2+ et Al 3+ et la comparaison avec les groupes fonctionnels avec la fluorescence infrarouge à transformée de Fourier (FTIR).Les résultats indiquent que le courant de masse du micro correspondent à une deuxième génération podzols qui se superposent sur gleysols et caractéristiques de distribution des acides fulviques et humiques sont liées à une partie des caractéristiques du sol telles que la texture et la variation de la nappe phréatique, de ce fait la distribution de substances humiques dans les différences de provaca du sol dans la dynamique de complexation des métaux entre l'acide fulvique et d'acide humique. Ainsi, alors que

Listas de Figuras Capítulo 1

Figura 1: Características morfológicas dos principais tipos de horizontes orgânicos das florestas segundo Duchaufour (1960). Mull, Moder e Mor, e as camadas Ao, A1 e L (resíduo) F (fermentação), H (camada superficial completamente humificada) .. Schulten & Schnitzer (1997), em que as esferas azuis, vermelhas, brancas e pretas representam os átomos de carbono, oxigênio, hidrogênio e nitrogênio, respectivamente. As letras A, B e C indicam os espaços "vazios" presentes na molécula das SH capazes de interagir com outros compostos ...................................................... Figura 5: Esquema de estrutura das substâncias húmicas proposto por [START_REF] Simpson | Molecular structures and associations of humic substances in the terrestrial environment[END_REF]. As unidades vermelhas representam os cátions metálicos, as unidades pretas os polissacarídeos, as unidades azuis os polipeptídios, as unidades verdes as cadeias alifáticas e as unidades marrons os fragmentos aromáticos provenientes da lignina .. 1.2.2. Mineralização e Humificação........................................................................................... 1.2. 2.5.Carbon Analysis................................................................................................................. 3.2.6 

Lista de Abreviatura e Siglas

AF

Introdução

A matéria orgânica do solo (MOS) é o resultado de uma mistura complexa de resíduos orgânicos (animais e vegetais) de diferentes naturezas e em diferentes estágios de decomposição (STEVENSON, 1994). Dependendo do seu estágio de decomposição as MOS podem ser classificadas em: liteira, substâncias não-húmicas e substâncias húmicas (SH) (STEVENSON, 1994).

As SH são moléculas polidispersas formadas a partir de reações químicas e bioquímicas durante o processo de decaimento e de transformação das matérias orgânicas, pelo processo de [START_REF] Lundström | The podzolization process. A review[END_REF][START_REF] Lundström | The podzolization process. A review[END_REF].

Estima-se que existam cerca de 485 milhões de hectares de podzóis no mundo (LEGROS, 2012), que foram descritos principalmente em regiões boreais ou frias do globo (LUNDSTRÖM; [START_REF] Lundström | The podzolization process. A review[END_REF][START_REF] Lundström | The podzolization process. A review[END_REF]. Todavia, a partir de 1950, este tipo de solo foi relatado em regiões tropicais (Costa do Marfim) (LENEUF; [START_REF] Leneuf | Les sols podzoliques du cordon littoral en basse Cote D'Ivoire[END_REF]. No Estado do Amazonas [START_REF] Klinge | Podzol soils in the Amazon Basin[END_REF] foi o pioneiro na descrição dos podzóis. Posteriormente, diversos autores mostraram interesse na compreensão da superimposição dos solos podzolizados sobre os Oxisolos, a partir de diferentes perspectivas pedo-geoquímicas (BRAVARD; [START_REF] Bravard | Podzols in Amazonia[END_REF][START_REF] Bueno | Appauvrissement et podzolisation des latérites du bassin du Rio Negro et gênese dês Podzols dans le haut bassin amazonien[END_REF][START_REF] Fritsch | Lateritic and redoximorphic features in a faulted landscape near Manaus, Brazil[END_REF][START_REF] Fritsch | Deciphering the weathering processes using environmental mineralogy and geochemistry: Towards an integrated model of laterite and podzol genesis in the Upper Amazon Basin Crystal chemistry of Al and Fe Kaolinite Fe-oxides Organo-metallic complexes Laterit[END_REF][START_REF] Lucas | Systemes sols ferrallitiques -podzols en region amazonienne[END_REF].

A superimposição dos solos podzolizados sobre os Oxisolos ocorre devido a fatores como a acumulação de espécies organo-metálicas em meio redutor e ácido [START_REF] Bardy | Podzolisation and exportation of organic matter in black waters of the Rio Negro (upper Amazon basin, Brazil)[END_REF]BRAVARD;[START_REF] Bravard | Podzols in Amazonia[END_REF][START_REF] Bueno | Appauvrissement et podzolisation des latérites du bassin du Rio Negro et gênese dês Podzols dans le haut bassin amazonien[END_REF][START_REF] Fritsch | Organic complexation and translocation of ferric iron in podzols of the Negro River watershed. Separation of secondary Fe species from Al species[END_REF][START_REF] Lucas | Systemes sols ferrallitiques -podzols en region amazonienne[END_REF], e envolve mudanças na dinâmica da MOS (BRAVARD;[START_REF] Bravard | Characterization of fulvic and humic acids from an oxisol-spodosol toposequence of Amazonia, Brazil[END_REF]. No entanto, compreender tal dinâmica pode contribuir no entendimento da podzolização em meio equatorial e também a dinâmica do carbono (C) no ambiente pedológico. Para atingir tal entendimento são necessárias a realização de estudos em diferentes perspectivas, entre elas, a análise das SH.

Dessa maneira, o presente trabalho objetiva a investigação das etapas de transformação da pedo-paisagem e da análise das substâncias húmicas dos solos podzolizados de uma micro-bacia localizada na bacia do Alto Rio Negro a partir da utilização dos métodos espectroscópicos com o intuito de compreender as funções das diferentes frações das matérias orgânicas.

No primeiro capítulo foi apresentada uma breve revisão bibliográfica sobre os temas abordados no trabalho: os solos da bacia Amazônica, o processo de podzolização e as técnicas espectroscópicas.

O segundo capítulo intitulado "Distribution of soils in a small catchment in the upper Negro

River basin -Brazilian Amazonia and the steps of transformation of a podzolized pedo-landscape" tem como objetivo examinar a distribuição espacial e as características de solos podzolizados e gleisolos, na escala da microbacia e apresentar as etapas de transformação da pedo-paisagem.

No terceiro capítulo, "Characterization and distribution of humics substance of a podzolized soils system in Upper Rio Negro-AM", o objetivo é caracterizar a distribuição dos ácidos fúlvicos e húmicos através de análises espectroscópicas de UV-Visible e FTIR.

No quarto capítulo, "Constante de Estabilidade (K) condicional e constante da capacidade de complexação para Cu(II) e Al(III) em amostras de ácidos fúlvicos e húmicos de solos podzolizados da bacia do Alto Rio Negro-AM, Brasil ", o objetivo foi identificar as componentes fluorescentes presentes nas substâncias húmicas dos solos podzolizados da microbacia e avaliar as constantes de estabilidade condicional (K) e a capacidade de ligação (CC) das componentes, presentes nos ácidos fúlvicos e húmicos, com a adição dos metais Cu 2+ e Al 3+ , e comparar com os grupos funcionais obtidos com a FTIR.

Nos anexos os dados dos extratos de ácidos fúlvicos e ácidos húmicos dos solos estão acessíveis para consulta.

Introduction

La matière organique du sol (MOS) est le résultat d'un mélange complexe de résidus organiques (animaux et plantes) de natures différentes et à différents stades de décomposition (STEVENSON, 1994). En fonction de leur stade de décomposition, la MOS peut être classée comme: litière, substances non humiques et substances humiques (SH) (STEVENSON, 1994).

Les SH sont des molécules polydisperses formées à partir de réactions chimiques et [START_REF] Lundström | The podzolization process. A review[END_REF][START_REF] Lundström | The podzolization process. A review[END_REF].

On estime qu'il y a environ 485 millions d'hectares de podzols dans le monde (LEGROS, 2012), qui ont été décrits principalement dans les régions boréales ou froides du globe (LUNDSTRÖM; [START_REF] Lundström | The podzolization process. A review[END_REF][START_REF] Lundström | The podzolization process. A review[END_REF]. Cependant, depuis 1950, ce type de sol a été également signalé dans les régions tropicales (Côte d'Ivoire) [START_REF] Leneuf | Les sols podzoliques du cordon littoral en basse Cote D'Ivoire[END_REF]. Dans la région amazonienne, [START_REF] Klinge | Podzol soils in the Amazon Basin[END_REF] a été le pionnier de la description des podzols. Par la suite, plusieurs auteurs se sont intéressés à la compréhension du chevauchement des sols podzols sur les ferralsols, à partir de différentes perspectives pédo-géochimiques (BRAVARD; [START_REF] Bravard | Podzols in Amazonia[END_REF][START_REF] Bueno | Appauvrissement et podzolisation des latérites du bassin du Rio Negro et gênese dês Podzols dans le haut bassin amazonien[END_REF][START_REF] Fritsch | Lateritic and redoximorphic features in a faulted landscape near Manaus, Brazil[END_REF][START_REF] Fritsch | Deciphering the weathering processes using environmental mineralogy and geochemistry: Towards an integrated model of laterite and podzol genesis in the Upper Amazon Basin Crystal chemistry of Al and Fe Kaolinite Fe-oxides Organo-metallic complexes Laterit[END_REF][START_REF] Lucas | Systemes sols ferrallitiques -podzols en region amazonienne[END_REF].

Le chevauchement des sols podzols sur les ferralsols se produit en raison de facteurs tels que l'accumulation d'espèces organométalliques en milieu réducteur et acide [START_REF] Bardy | Podzolisation and exportation of organic matter in black waters of the Rio Negro (upper Amazon basin, Brazil)[END_REF]BRAVARD et al., 2011;[START_REF] Lucas | Systemes sols ferrallitiques -podzols en region amazonienne[END_REF], et implique des changements dans la dynamique de la MOS (BRAVARD;[START_REF] Bravard | Characterization of fulvic and humic acids from an oxisol-spodosol toposequence of Amazonia, Brazil[END_REF]. Ainsi, la compréhension de cette dynamique peut contribuer à la compréhension de la podzolisation dans l'environnement équatorial et aussi de la dynamique du carbone (C) dans l'environnement pédologique. Afin de parvenir à cette compréhension, il est nécessaire de mener des études dans différentes perspectives, parmi lesquels l'analyse des SH. [START_REF] Do | Podzolization as a deferralitization process: A study of an Acrisol-Podzol sequence derived from Palaeozoic sandstones in the northern upper Amazon Basin[END_REF][START_REF] Fritsch | Deciphering the weathering processes using environmental mineralogy and geochemistry: Towards an integrated model of laterite and podzol genesis in the Upper Amazon Basin Crystal chemistry of Al and Fe Kaolinite Fe-oxides Organo-metallic complexes Laterit[END_REF], das matérias orgânicas dos solo e das substâncias húmicas e, por fim, tratou das técnicas espectroscópicas.

De

Solos da bacia Amazônica

Solos Podzolizados

Os podzóis tem forte diferença entre horizontes. São, diagnosticados pela presença do horizonte espódico (Bh), no qual se acumulam matéria orgânica e compostos organo-metálicos e/ou compostos inorgânicos de Fe e de Al (LUNDSTRÖM; [START_REF] Lundström | The podzolization process. A review[END_REF][START_REF] Lundström | The podzolization process. A review[END_REF]. Sobre os horizontes espódicos encontram-se horizontes A e AE e o horizonte oriundo de eluviação (E). O último,chamado de álbico, é arenoso, e nos podzóis gigantes pode ultrapassar os 10 metros de espessura [START_REF] Klinge | Podzol soils in the Amazon Basin[END_REF]LUCAS et al., 1986;DUBROEUCQ e VOLKOFF, 1998;). [START_REF] Lundström | The podzolization process. A review[END_REF][START_REF] Lundström | The podzolization process. A review[END_REF].

Normalmente esses solos apresentam alta acidez, baixa fertilidade química e matéria orgânica do tipo Mor (LUNDSTRÖM; [START_REF] Lundström | The podzolization process. A review[END_REF][START_REF] Lundström | The podzolization process. A review[END_REF]. A matéria orgânica geralmente tem baixa atividade biológica e mineralização menos intensa, o que reflete na acumulação de matéria orgânica pouco transformada. São pobres em argila, o que impede a formação de agregados argilohúmicos. A cobertura vegetal presente é de porte arbóreo, constituída de árvores de troncos finos e curtos.

Os podzóis hidromórficos apresentam cores menos fortes e são dominados pela presença significativa de compostos orgânicos de cor marrom escura. O acúmulo de água superficial favorece o desenvolvimento de condições de redução, e, assim, a uma maior mobilidade de ferro nessas formações. Os horizontes espódicos são quase sempre do tipo Bh ou Bhs [START_REF] Bueno | Appauvrissement et podzolisation des latérites du bassin du Rio Negro et gênese dês Podzols dans le haut bassin amazonien[END_REF].

Nos podzóis bem drenados, os contrastes de cor entre os horizontes são mais fortes. Há maior mineralização dos compostos orgânicos, o que limita sua acumulação nos horizontes espódicos mais profundos. Com o estabelecimento de melhores condições de drenagem, o que ocorre em determinadas épocas do ano, o ambiente torna-se propício para a precipitação de Fe, que dá coloração vermelho-acastanhada a vermelho brilhante para os horizontes espódicos desses solos (Bs) [START_REF] Bueno | Appauvrissement et podzolisation des latérites du bassin du Rio Negro et gênese dês Podzols dans le haut bassin amazonien[END_REF].

Os podzóis amazônicos são encontrados sobre os baixos platôs e ligados ou não à rede de drenagem principal [START_REF] Bueno | Appauvrissement et podzolisation des latérites du bassin du Rio Negro et gênese dês Podzols dans le haut bassin amazonien[END_REF]. Na parte média da bacia do Rio Negro, estes solos são pouco desenvolvidos e ocupam, como os solos hidromórficos (Gleissolos), zonas deprimidas sobre esses platôs (região do Jaú) [START_REF] Do | Podzolization as a deferralitization process: A study of an Acrisol-Podzol sequence derived from Palaeozoic sandstones in the northern upper Amazon Basin[END_REF]. Na parte da montante mais chuvosa da bacia do Rio Negro (região de São Gabriel da Cachoeira), esses solos estão diretamente conectados aos eixos de drenagem principais da bacia do Rio Negro [START_REF] Bueno | Appauvrissement et podzolisation des latérites du bassin du Rio Negro et gênese dês Podzols dans le haut bassin amazonien[END_REF]. A coloração escura dos rios confirma que a expansão dos podzóis em áreas alagadas nos planaltos ainda está em curso [START_REF] Do | Podzolization as a deferralitization process: A study of an Acrisol-Podzol sequence derived from Palaeozoic sandstones in the northern upper Amazon Basin[END_REF].

Na bacia do Rio Negro os podzóis que não se encontram associados à rede de drenagem são os podzóis hidromórficos e sua distribuição na paisagem é controlada pelo relevo. Sua distribuição é semelhante à dos gleissolos, porém sua origem é diferente, pois está associada ao empobrecimento das coberturas lateríticas [START_REF] Bueno | Appauvrissement et podzolisation des latérites du bassin du Rio Negro et gênese dês Podzols dans le haut bassin amazonien[END_REF].

Criptopodzóis

Quando os solos podzolizados são menos desenvolvidos e apresentam horizonte E álbico difuso ou inexistente, sobreposto a horizonte espódico são conhecidos como Criptopodzóis (DO [START_REF] Do | Podzolization as a deferralitization process: A study of an Acrisol-Podzol sequence derived from Palaeozoic sandstones in the northern upper Amazon Basin[END_REF]DUCHAFOUR, 1997). São solos que possuem elevado teor de matéria orgânica acumulada em horizontes de superfície [START_REF] Do | Podzolization as a deferralitization process: A study of an Acrisol-Podzol sequence derived from Palaeozoic sandstones in the northern upper Amazon Basin[END_REF]DUCHAFOUR, 1997;LEGROS, 2012).

Estão , 1977), apresentam processos de empobrecimento em argila e são superimpostos pela podzolização (BRAVARD; [START_REF] Bravard | Podzols in Amazonia[END_REF][START_REF] Do | Podzolization as a deferralitization process: Dynamics and chemistry of ground and surface waters in an Acrisol -Podzol sequence of the upper Amazon Basin[END_REF][START_REF] Dubroeucq | From Oxisols to Spodosols and Histosols: evolution of the soil mantles in the Rio Negro basin (Amazonia)[END_REF][START_REF] Dubroeucq | From Oxisols to Spodosols and Histosols: evolution of the soil mantles in the Rio Negro basin (Amazonia)[END_REF][START_REF] Fritsch | Organic complexation and translocation of ferric iron in podzols of the Negro River watershed. Separation of secondary Fe species from Al species[END_REF][START_REF] Lucas | Systemes sols ferrallitiques -podzols en region amazonienne[END_REF].

Acrissolos

O empobrecimento em materiais finos dos solos lateríticos através da transformação lateral pode favorecer o aparecimento de uma nova geração de solo, conhecidos como Acrissolos (FAO,1998) [START_REF] Do | Podzolization as a deferralitization process: Dynamics and chemistry of ground and surface waters in an Acrisol -Podzol sequence of the upper Amazon Basin[END_REF] (Argissolo na classificação SiBCS).

Em regiões tropicais úmidas, o aparecimento deste tipo de solo ocorre devido a um processo inicial de empobrecimento em materiais finos e, então, aumento relativo da textura arenosa, atribuída à hidratação mais elevada dos solos e a mecanismos de auto desenvolvimento e amarelamento dos solos lateríticos [START_REF] Fritsch | Organic complexation and translocation of ferric iron in podzols of the Negro River watershed. Separation of secondary Fe species from Al species[END_REF].

O processo de amarelecimento do solo leva a formação da goethita aluminosa, caracterizada por uma substituição mais forte de alumínio, anterior à formação da gibsita que, portanto, marcam o início da mobilidade do alumínio nos perfis de oxisolos ou lateritas móveis [START_REF] Do | Podzolization as a deferralitization process: A study of an Acrisol-Podzol sequence derived from Palaeozoic sandstones in the northern upper Amazon Basin[END_REF].

Esses solos mais amarelos e mais pobres em argila podem existir nos topos planos dos platôs (BUENO, 2009) e também ao longo de vertentes, nos segmentos que separam os espodossolos de jusante, dos oxisolos argilosos, de montante [START_REF] Lucas | Systemes sols ferrallitiques -podzols en region amazonienne[END_REF].

Solos Hidromórficos: Gleissolos

Os solos que estão conectados às redes de drenagem e possuem uma dinâmica controlada principalmente pela flutuação das águas subterrâneas são conhecidos como gleissolos.

O processo de formação destes é denominado gleização [START_REF] Fanning | Soil morphology, genesis and classification[END_REF]FANNING, 1989). A saturação de água prolongada nos ambientes favorece a ausência de oxigênio e a presença de microorganismos anaeróbicos, induzindo a redução de Fe³⁺ (presente nos minerais de goethita, hematita, ferridrita e lepidocrocita) para Fe²⁺ em partes do solo. O Fe²⁺ é solúvel favorecendo sua mobilidade no perfil. A redução é seguida pela oxidação de Fe²⁺ para Fe³⁺ e pela precipitação na forma de óxidos de ferro no perfil [START_REF] Fanning | Soil morphology, genesis and classification[END_REF]FANNING, 1989).

Esse processo de redução provoca o empalidecimento, coloração gley (baixo chroma) nas partes do perfil onde ocorre saturação pela água e consequente perda de Fe, contudo, apresenta coloração mais forte (aumento do chroma) nos horizontes onde há acumulação dos óxidos pela oxidação [START_REF] Fanning | Soil morphology, genesis and classification[END_REF]FANNING, 1989). Apresentam, ainda, textura fina (maior presença da fração argila) e acumulação de matéria orgânica nas partes superiores do perfil.

Na bacia Amazônica são solos que normalmente ocupam as planícies e depressões do platô [START_REF] Bueno | Appauvrissement et podzolisation des latérites du bassin du Rio Negro et gênese dês Podzols dans le haut bassin amazonien[END_REF][START_REF] Fritsch | Deciphering the weathering processes using environmental mineralogy and geochemistry: Towards an integrated model of laterite and podzol genesis in the Upper Amazon Basin Crystal chemistry of Al and Fe Kaolinite Fe-oxides Organo-metallic complexes Laterit[END_REF]. A cobertura vegetal presente é de porte arbóreo, constituída de árvores de troncos finos e curtos.

Matéria orgânica do solo

A matéria orgânica do solo (MOS) é o resultado de uma mistura complexa de resíduos orgânicos (animais e vegetais) de diversas naturezas e em diferentes estágios de decomposição, resultantes de degradação química, biológica e da atividade sintética dos microrganismos (STEVENSON, 1994). O teor de matéria orgânica (MO) presente no solo é resultado do balanço entre processos de adição de material orgânico (restos de plantas, animais, etc.) e perda (decomposição desses materiais pelos micro-organismos). Parte do carbono presente nos resíduos é liberada para a atmosfera na forma de CO e o restante passa a fazer parte da matéria orgânica como componente do solo [START_REF] Bayer | Tillage and cropping system effects on soil humic acid characteristics as determined by electron spin resonance and fluorescence spectroscopies[END_REF]STEVENSON, 1994). Segundo, Primo et al. (2001), a MOS constitui um dos reservatórios de carbono da superfície terrestre, chamando a atenção para a necessidade de conservação dos solos e de suas MO.

A porcentagem de MO encontrada nos solos é pequena quando comparada com a fração mineral, em que sua quantidade varia de acordo com o clima, o tipo de vegetação ou cobertura, textura, regime de saturação hídrica e, ainda, manejo e uso. Ela é composta principalmente por carbono, nitrogênio, fósforo e enxofre (ROCHA; ROSA, 2003). Embora a quantidade seja pequena, a MO desempenha um importante papel como fonte de nitrogênio para as plantas e é fornecedora de elementos como fósforo, enxofre e diversos micronutrientes. Além disso, é constituída por diferentes compostos de carbono em vários graus de alteração e de interação com as outras fases do solo.

Interfere também em várias propriedades do solo, tais como adsorção de cátions e ânions, complexação de metais, estabilização da estrutura do solo, retenção de água, influencia diretamente na cor, reduz a plasticidade e provoca sensível diminuição na compactação, por aumentar a porosidade do solo (STEVENSON, 1994). Stevenson (1994) Antes de chegar ao estágio de húmus estável, a matéria orgânica fresca, que entrou em contato com o solo, passa por processos fundamentais de transformação, os quais são conhecidos como Mineralização e Humificação.

Classificação da Matéria Orgânica do Solo

Mineralização e Humificação

A mineralização está associada na sua origem, a minerais solúveis ou gasosos (Duchaufour, 1960) e é definida, por [START_REF] Zech | Factors controlling humification and mineralization of soil organic matter in the tropics[END_REF], como a transformação de elementos organicamente ligados (C, N, S, P) em compostos inorgânicos (CO , CH , NH ⁺, NO ¯, SO² ¯, HPO ²¯), ou seja, é o processo de liberação de minerais para os solos e de gases para a atmosfera. A velocidade de mineralização e a quantidade de nutrientes liberados varia entre as diferentes frações da matéria orgânica do solo.

O processo de humificação é a transformação de substâncias macro-morfológicas identificáveis em substâncias húmicas amorfas [START_REF] Zech | Factors controlling humification and mineralization of soil organic matter in the tropics[END_REF]. É o processo no qual se dá a formação de húmus. São produtos mais estáveis e resistentes à ação microbiana. As substâncias húmicas originam-se a partir da celulose, lignina, proteínas, lipídios e de outras substâncias pela degradação química e biológica, ou da ressíntese em um grupo amorfo de substâncias de coloração castanho-escura com estruturas químicas complexas de maior estabilidade do que os materiais que as originaram, bem como com estrutura e natureza particulares (STEVENSON, 1994). As principais transformações que ocorrem durante o processo de humificação são a modificação das estruturas da lignina pela perda de compostos fenólicos e polissacarídeos e o enriquecimento em estruturas aromáticas não lignínicas recalcitrantes [START_REF] Zech | Factors controlling humification and mineralization of soil organic matter in the tropics[END_REF]. Não apenas microorganismos, mas também animais do solo participam do processo de humificação e, assim, pode-se dizer que ocorrem transformações físicas, químicas e biológicas ao invés de apenas microbiana e química [START_REF] Zech | Factors controlling humification and mineralization of soil organic matter in the tropics[END_REF].

A velocidade dos processos de mineralização e humificação é variada e podem ser influenciados principalmente pelo clima e por fatores físico-químicos, como pH, relação carbono/nitrogênio(C/N), entre outros [START_REF] Zech | Factors controlling humification and mineralization of soil organic matter in the tropics[END_REF].

Os tipos de Húmus

Os resíduos orgânicos, assim que adicionados ao solos, iniciam processos de decomposição, porém a velocidade destes processos não são os mesmos para todos os materiais e dependem de parâmetros como velocidade da mineralização, importância do fenômeno de biossíntese, natureza dos Mor é conhecido também como húmus bruto. É um húmus de decomposição lenta; o horizonte A é espesso e formado por elementos não decompostos e intermediários, o que causa a divisão desta em três outras camadas: camada L, formada por produtos ainda sem decomposição; camada F, de fermentação, e camada H, de humificação, compreendida por complexos húmicos em mistura com produtos intermediários. O horizonte A é fino com a presença de produtos intermediários e compostos húmicos muito ácidos. O pH de formação encontra-se na faixa inferior a 5 (na maioria da vezes na ordem de 4 a 4.5) e a relação C/N é superior a 20 em A .

Substâncias Húmicas

As substâncias húmicas (SH) estão presentes no meio natural, ocorrendo em grandes quantidades nos solos, sedimentos e na água [START_REF] Malcolm | The uniqueness of humic substances in each of soil, stream and marine environments[END_REF][START_REF] Thacker | Development and application of functional assays for freshwater dissolved organic matter[END_REF] STEVENSON, 1994).

Com base na sua solubilidade em meio aquoso, as substância húmicas são divididas em:

 Ácidos Fúlvicos: fração que permanece em solução quando o extrato alcalino é acidificado e possui maior presença de grupamentos carboxílicos e de oxigênio;

 Ácidos Húmicos: fração escura solúvel em extrato alcalino, que precipita após a acidificação.

Representam também a porção mais estável da matéria orgânica;

 Humina: fração insolúvel em qualquer intervalo de pH.

1. Formação das substâncias húmicas e modelos

Existem diversas teorias sobre a formação das substâncias húmicas, porém a teoria clássica, popularizada por Waksman (STEVENSON, 1994), propõe que as substâncias húmicas são ligninas modificadas, porém esta hipótese foi considerada incompleta e alguns autores também consideram o envolvimento das quinonas, que são produtos derivados da lignina no processo de formação das substâncias húmicas (STEVENSON, 1994).

A Figura 2 esquematiza a proposta de Stevenson (1994) sobre a formação das substâncias húmicas. Este autor explana quatro vias principais: no mecanismo 1, propõe-se a formação de húmus a partir da polimerização não enzimática por condensação entre aminoácidos e açúcares, formados como subprodutos da atividade microbiana; nos mecanismos 2 e 3 estão envolvidas a participação de polifenóis e quinonas, e no mecanismo 4 estão os produtos derivados das ligninas modificadas.

Figura 2: Principais vias propostas para a formação de substâncias húmicas pela decomposição de resíduos animais e vegetais no solo.

Fonte: Adaptado de Stevenson, 1994. Uma segunda questão que envolve as substâncias húmicas é a estrutura química das mesmas.

Desde a década de 1960, modelos para tal estrutura são propostos (KONONOVA, 1961;SCHNITZER, 1978), porém, segundo Stevenson (1994), nenhuma foi inteiramente satisfatória.

Esta dificuldade ocorre devido a heterogeneidade e a complexidade das substâncias húmicas, bem como a ausência de sua identidade estrutural genética. [START_REF] Schulten | A State of the Art Structural Concept for Humic Substances[END_REF], baseados em estudos espectroscópicos, pirólise, degradação oxidativa e microscopia eletrônica, apresentaram um modelo estrutural para o ácido húmico (Figura 3). No modelo proposto por [START_REF] Schulten | A State of the Art Structural Concept for Humic Substances[END_REF], as SH apresentam grandes porções de grupos funcionais alifáticos; as funções oxigenadas estão presentes nos grupos funcionais carboxílicos, hidroxílicos, fenólicos, éter e éster. A composição elementar da estrutura do ácido húmico é C308H328O90N5 e tem tamanho molecular de 5540 Da (SCHULTEN;[START_REF] Schulten | A State of the Art Structural Concept for Humic Substances[END_REF]. Em 1997 os mesmo autores propuseram um modelo tridimensional para o ácido húmico, que foi chamado de macromolecular (Figura 4). Neste modelo, as variações conformacionais das SH são similares àquelas observadas nas macromoléculas biológicas, como proteínas, polissacarídeos, ácidos nucléicos e ligninas (Fig. 4) (SWIFT, 1999), e dependem da concentração das moléculas húmicas, do pH (SENESI, 1990) e da concentração iônica [START_REF] Schulten | A State of the Art Structural Concept for Humic Substances[END_REF][START_REF] Schulten | A State of the Art Structural Concept for Humic Substances[END_REF]. Além disso, o modelo tridimensional apresenta uma série de espaços vazios de diferentes tamanhos no interior da macromolécula, os quais poderiam alojar outros compostos orgânicos hidrofóbicos ou hidrofílicos, como proteínas, carboidratos, pesticidas, lipídios e agrotóxicos [START_REF] Schulten | A State of the Art Structural Concept for Humic Substances[END_REF][START_REF] Schulten | A State of the Art Structural Concept for Humic Substances[END_REF]. [START_REF] Piccolo | The supramolecular structure of humic substances: A novel understanding of humic chemistry and implication in soils science[END_REF] , 2002). [START_REF] Simpson | Molecular structures and associations of humic substances in the terrestrial environment[END_REF] reforçam o modelo supramolecular proposto por [START_REF] Piccolo | The supramolecular structure of humic substances: A novel understanding of humic chemistry and implication in soils science[END_REF], demonstrando que SH extraídas dos solos são uma mistura de substâncias de baixo peso molecular (em torno de 2000 Da) e propuseram um esquema de estrutura apresentado na figura 5.

Figura 5: Esquema de estrutura das substâncias húmicas proposto por [START_REF] Simpson | Molecular structures and associations of humic substances in the terrestrial environment[END_REF]. As unidades vermelhas representam os cátions metálicos, as unidades pretas os polissacarídeos, as unidades azuis os polipeptídios, as unidades verdes as cadeias alifáticas e as unidades marrons os fragmentos aromáticos provenientes da lignina Fonte: [START_REF] Simpson | Molecular structures and associations of humic substances in the terrestrial environment[END_REF] Porém, um modelo aceito por toda a comunidade científica para a estrutura das SH ainda encontra-se indefinido, de modo que para tanto novos procedimentos analíticos encontram-se em desenvolvimento, visando a obtenção de resultados mais contundentes para suportar as hipóteses propostas. Enquanto isso, a compreensão sobre a dinâmica destas substâncias nos ecossistemas é realizada devido a sua participação na dinâmica geoquímica dos ambientes. Elas desempenham papel importante nos processos geoquímicos do ambiente por diferentes razões, como, por exemplo, atuando em propriedades químicas e físicas, influenciando na biodisponibilidade de metais do solo para plantas e/ou organismos e na toxicidade de alguns metais e no transporte, no acúmulo e na concentração de espécies metálicas; dependendo das condições do meio, possuem características óxido-redutoras e influenciam no mecanismo de sorção no solo de gases orgânicos e inorgânicos presentes na atmosfera, entre outras funções.

Interação das substâncias húmicas com metais

Uma das propriedades das SH é de interagir com os íons metálicos presentes nos solos, nas águas e nos sedimentos (Fe, Mn, Cu, Zn, Al, entre outros), formando complexos organometálicos e/ou quelatos de diferentes estabilidades e características estruturais (Senesi et al.,1996). Essa interação se dá com inúmeros grupos funcionais que possuem oxigênio, principalmente os grupos carboxílicos e fenólicos, que formam interações eletrostáticas na superfície das macromoléculas [START_REF] Benedetti | Metal ion binding by natural organic matter: From the model to the field[END_REF][START_REF] Marinsky | Proton and metal ion binding to natural organic polyelectrolytes-I. Studies with synthetic model compounds[END_REF][START_REF] Marinsky | Proton and metal ion binding to natural organic polyelectrolytes-I. Studies with synthetic model compounds[END_REF][START_REF] Tipping | A unifying model of cation binding by humic substances[END_REF][START_REF] Tipping | A unifying model of cation binding by humic substances[END_REF], o que lhes confere a habilidade de formar complexos com os cátions metálicos (SENESI; SPOSITO; [START_REF] Senesi | Copper(II) and iron(III) complexation by soil humic acids: An IR and ESR study[END_REF]STEVENSON, 1994), cuja estabilidade das espécies é determinada por uma série de fatores, incluindo o número de átomos que forma a ligação com o metal, a natureza e a concentração de íon metálico, a concentração das SH, o pH, o tempo de complexação, entre outros. O material húmico também possui a habilidade de aderir partículas minerais, produzindo agregados com aumento significativo em sua adsorção ou na capacidade de complexação (STEVENSON, 1994).

Caracterização das substância húmicas e técnicas espectroscópicas

Diferentes técnicas são indicadas na literatura para analisar e caracterizar as SH, dentre elas está a espectroscopia, que estuda a interação da radiação eletromagnética com a matéria. A radiação e a matéria podem interactuar de várias formas, como, por exemplo, por processos de absorção, emissão, difusão, difração, entre outros, e podem emitir radiação na região do ultravioleta e do visível em estados moleculares de transição vibracional, na região do infravermelho e na região do micro-ondas e, ainda, em casos particulares, na região do infravermelho longínquo [START_REF] Goodman | Molecular spectroscopy: Introduction and general principles[END_REF].

As espectroscopias nas regiões do UV-Visível (UV-Vis), Infravermelho e Fluorescência, são técnicas espectroscópicas atualmente muito utilizadas na caracterização das matérias orgânicas porque podem fornecer informações sobre a fonte e a composição destas substâncias presentes nos sistemas naturais [START_REF] Birdwell | Characterization of dissolved organic matter in cave and spring waters using UV-Vis absorbance and fluorescence spectroscopy. Organic Geochemistry[END_REF]ENGEL, 2010a;[START_REF] Coble | Characterization of marine and terrestrial DOM in seawater using excitationemission matrix spectroscopy[END_REF][START_REF] Hudson | Fluorescence analysis of dissolved organic matter in natural, waste and polluted waters -A reviewRiver Research and Applications[END_REF][START_REF] Hudson | Fluorescence analysis of dissolved organic matter in natural, waste and polluted waters -A reviewRiver Research and Applications[END_REF][START_REF] Hudson | Fluorescence analysis of dissolved organic matter in natural, waste and polluted waters -A reviewRiver Research and Applications[END_REF].

A utilização de tais técnicas são vantajosas, pois são de fácil execução e necessitam de pequenas quantidades de amostras (STEVENSON, 1994). Por essa razão, são amplamente utilizadas nas pesquisas científicas para compreender a estrutura e o funcionamento químico das MO. Cada técnica oferece determinadas informações e seus resultados complementam-se entre si, evidenciando tendências e peculiaridades das amostras analisadas.

Espectroscopia de Absorbância de radiação no UltraVioleta-Visível

A Espectroscopia na região do Ultravioleta (200-400 nm) e do UltraVioleta-Visível (400-800 nm) permite a identificação de transições de elétrons dos orbitais moleculares σ-, πe n-de seu estado energético fundamental para orbitais de maior energia em um estado excitado (SKOOG; HOLLER; NIEMAN, 2002). Na Espectroscopia de absorbância no UltraVioleta-Visível (Uv-Visível), os elétrons de ligação são excitados e os resultados obtidos referem-se aos comprimentos de onda dos picos de absorção, que podem ser correlacionados com os tipos de ligações das espécies estudadas (SKOOG; HOLLER; NIEMAN, 2002).

A absorção de radiação UV-Visível de maior comprimento de onda está restrita a um número limitado de grupos funcionais (chamados cromóforos) que contêm elétrons de valência com energias de excitação relativamente baixas. Os elétrons que contribuem para a absorção em uma molécula orgânica são aqueles que participam diretamente na formação de ligação entre átomos e, portanto, estão associados a mais de um átomo e elétrons não-ligantes ou isolados externos que estão comumente localizados em átomos como oxigênio, halogênios, enxofre e nitrogênio (SKOOG; HOLLER; NIEMAN, 2002).

Em função da grande quantidade e variabilidade de grupos cromóforos existentes nas macromoléculas húmicas, os espectros obtidos são geralmente formados pela sobreposição de várias bandas, sem picos definidos, apresentando absorção decrescente com o aumento do comprimento de onda. Os grupos responsáveis pela cor escura das substâncias húmicas ainda não estão completamente estabelecidos, mas se suspeita de uma combinação de vários tipos de estruturas (Figura 6). Alguns dos grupos mais comuns Stevenson (1994) estão apresentados na figura 1.6. Figura 1.6: Representação dos grupos cromóforos presentes nas substâncias húmicas Fonte: Stevenson, 1994 De maneira geral, a técnica de absorção no UV-Vis apresenta um gráfico de diminuição exponencial com o aumento do comprimento de onda (BIRDWELL; ENGEL, 2010; STEVENSON, 1994) e sua interpretação tem sido documentada na literatura para caracterizar e avaliar o grau de aromaticidade das SH através do uso das razões de absorbância (FUENTES; GONZÁLEZ-GAITANO; [START_REF] Fuentes | The usefulness of UV-visible and fluorescence spectroscopies to study the chemical nature of humic substances from soils and composts[END_REF][START_REF] Mcdonald | Analytical chemistry of freshwater humic substances[END_REF][START_REF] Vieyra | Combined UV-Vis absorbance and fluorescence properties of extracted humic substances-like for characterization of composting evolution of domestic solid wastes[END_REF][START_REF] Zara | A structural conformation study of aquatic humic acid[END_REF] Dentre estas, destacam-se as razões E 4 /E 6 (465 e 665 nm) e E 2 /E 3 (250 e 365 nm). A primeira razão é utilizada para avaliar o grau de condensação das estruturas aromáticas presentes nas matérias orgânicas (PEURAVUORI; [START_REF] Peuravuori | Molecular size distribution and spectroscopic properties of aquatic humic substances[END_REF]STEVENSON, 1994). A razão E2/E3, por sua vez, permite avaliar a aromaticidade e o tamanho molecular (PEURAVUORI; PIHLAJA, 1997).

1.3.2.Espectroscopia de Fluorescência de Luz UV-Vísivel

A fluorescência é um fenômeno conhecido como fotoluminescência, em que as moléculas são excitadas, por uma radiação eletromagnética, a um estado excitado singleto, e ao retornarem ao estado fundamental, ocorre a emissão de um fóton (LAKOWICZ, 2006). Dessa maneira, na fluorescência, os elétrons da molécula de interesse são excitados e transferidos de orbitais moleculares do estado fundamental para orbitais moleculares ligantes e antiligantes no estado excitado.

Normalmente a fluorescência é encontrada em compostos que contém grupos funcionais aromáticos com níveis de transição π → π* de baixa energia e compostos que contém estruturas funcionais mais alifáticas, carboxílicas, como, por exemplo, as SH (SKOOG; HOLLER; NIEMAN, 2002).

A intensidade, o deslocamento e a posição dos picos de fluorescência podem estar relacionados com a presença de elétrons doadores e/ou receptores de grupos, a policondensação, a aromaticidade, a heterogeneidade e a propriedades químicas [START_REF] Chen | Spectroscopic Characterization of Structural and Functional Properties of Natural Organic Matter Fractions Jie Chen[END_REF]PEURAVUORI;[START_REF] Peuravuori | Characterization, differentiation and classification of aquatic humic matter separated with different sorbents: Synchronous scanning fluorescence spectroscopy[END_REF][START_REF] Peuravuori | Characterization, differentiation and classification of aquatic humic matter separated with different sorbents: Synchronous scanning fluorescence spectroscopy[END_REF].

Aplicada aos estudos de SH, a Espectroscopia de Fluorescência pode fornecer informações tais como: diferenciar e classificar as SH baseadas nas características estruturais típicas responsáveis pela fluorescência [START_REF] Bayer | Tillage and cropping system effects on soil humic acid characteristics as determined by electron spin resonance and fluorescence spectroscopies[END_REF]MILORI et al., 2002) e identificar aspectos qualitativos no nível molecular das interações das substâncias húmicas com íons metálicos [START_REF] Bayer | Tillage and cropping system effects on soil humic acid characteristics as determined by electron spin resonance and fluorescence spectroscopies[END_REF].

Alguns procedimentos metodológicos, descritos na literatura, sugerem aplicar a fluorescência para avaliar o grau de humificação das SH (KALBITZ; GEYER; [START_REF] Kalbitz | Spectroscopic properties of dissolved humic substancesa reflection of land use history in a fen area[END_REF]MILORI et al., 2002;[START_REF] Zsolnay | Differentiating with fluorescence spectroscopy the sources of dissolved organic matter in soils subjected to drying[END_REF].

Os espectros bidimensionais de Fluorescência podem ser obtidos em três modos: emissão, excitação e sincronizado [START_REF] Senesi | Binding mechanisms of pesticides to soil humic substances[END_REF]. Os espectros de emissão são obtidos medindo a intensidade relativa da radiação emitida em função do comprimento de onda . Os espectros de excitação são obtidos medindo a intensidade de luminescência em um comprimento de onda de excitação variado. O espectro de varredura sincronizado de excitação é obtido pela medida da intensidade de fluorescência durante uma varredura simultaneamente de ambos os comprimentos de onda, excitação e emissão, e mantendo constante, entre eles, uma diferença de comprimento de onda otimizada Δ = em -exc.

O avanço dos sistemas operacionais permitiu que os Espectros de Fluorescência pudessem ser obtidos também no modo tridimensional, conhecido como Excitation-Emission Matrix Spectroscopy (EEM) [START_REF] Coble | Characterization of marine and terrestrial DOM in seawater using excitationemission matrix spectroscopy[END_REF]. Esta técnica vem sendo utilizada desde a década de 1990, com o objetivo de analisar a matéria orgânica dissolvida, apresentando resultados satisfatórios [START_REF] Chen | Spectroscopic Characterization of Structural and Functional Properties of Natural Organic Matter Fractions Jie Chen[END_REF]COBLE, 2007a;[START_REF] Mcknight | Spectrofluorometric characterization of dissolved organic matter for indication of precursor organic material and aromaticity[END_REF][START_REF] Mounier | Differentiation of organic matter's properties of the Rio Negro basin by crossflow ultra-filtration and UV-spectrofluorescence[END_REF].

Com a utilização da fluorescência EEM é possível obter espectros de emissão de múltiplas faixas de excitação que são conectados à matriz, o que permite a classificação da fonte do material orgânico com base nos fluoróforos presentes (COBLE, 2007a). Uma das principais vantagens desta técnica é apresentar resultados sobre a composição da MOS e das SH. As características de fluorescência são adquiridas através da mudança do comprimento de onda de excitação e emissão simultaneamente [START_REF] Murphy | Measurement of dissolved organic matter fluorescence in aquatic environments: An interlaboratory comparison[END_REF]. A EEM, a partir da interpretação dos picos presentes nos espectros, fornece informações sobre as mudanças da matéria orgânica resultantes da mistura de compostos, da degradação biológica e da produção biológica que ocorrem no ambiente (COBLE, 2007a).

Além disso, o espectro de EEM pode ser utilizado para a caracterização quantitativa da matéria orgânica fluorescente (MOF) quando combinado com técnicas estatísticas de decomposição de dados multivariados, tais como Análise de Fator Paralelo (CP/PARAFAC), que facilita a identificação e a quantificação de sinais subjacentes, denominados componentes [START_REF] Murphy | Measurement of dissolved organic matter fluorescence in aquatic environments: An interlaboratory comparison[END_REF].

A EEM-CP/PARAFAC é uma técnica potencialmente útil na avaliação das amostras complexas, tais como são as substâncias húmicas. Esta técnica permite a avaliação da decomposição dos componentes fluorescentes, independente do complexo formado na EEM, que representam grupos que são denominados de componentes fluorescentes [START_REF] Guo | Characterizing the fluorescent properties and copper complexation of dissolved organic matter in saline-alkali soils using fluorescence excitation-emission matrix and parallel factor analysis[END_REF][START_REF] Luciani | Tracing of dissolved organic matter from the SEPETIBA Bay (Brazil) by PARAFAC analysis of total luminescence matrices[END_REF][START_REF] Sierra | Fluorescence fingerprint of fulvic and humic acids from varied origins as viewed by single-scan and excitation/emission matrix techniquesChemosphere[END_REF] Para a matéria orgânica do solo, o CP/PARAFAC permite identificar compostos, desde os mais gerais, como proteínas e ácidos húmicos, até compostos específicos, como triptófano, tirosina e quinonas [START_REF] Murphy | Measurement of dissolved organic matter fluorescence in aquatic environments: An interlaboratory comparison[END_REF], fornecendo uma decomposição espectral facilmente interpretável.

A combinação EEM e CP/PARAFAC é considerada uma ferramenta importante na interpretação de dados multidimensionais e em estudos de caracterização da matéria orgânica porque permite identificar com detalhes as características naturais das matérias orgânicas e das substâncias húmicas [START_REF] Guo | Characterizing the fluorescent properties and copper complexation of dissolved organic matter in saline-alkali soils using fluorescence excitation-emission matrix and parallel factor analysis[END_REF].

Fluorescência quenching

A espectroscopia de fluorescência é uma importante ferramenta para o estudo da reatividade dos sistemas químicos e biológicos, uma vez que permite medições não-intrusivas de substâncias em baixas concentrações. A fluorescência quenching ou supressão de fluorescência é uma derivação da Espectroscopia de Fluorescência, a qual utiliza o princípio de que a intensidade de fluorescência pode ser diminuída devido a uma variedade de processos (LAKOWICZ, 2006). Tal diminuição da intensidade é conhecida como quenching.

A variedade de interações moleculares pode resultar na supressão, como, por exemplo, reações de estado excitado, rearranjos moleculares, transferência de energia, formação de complexo de estado fundamental e supressão colisional (LAKOWICZ, 2006). A supressão na amostra pode ser ocasionada também por dois mecanismos, supressão dinâmica (quenching dinâmico) e/ou supressão estática (quenching estático).

O quenthing dinâmico ocorre no estado fundamental da molécula e não depende de difusão molecular ou colisão. O quenching estático é quando ocorre uma atenuação da luz incidente através da própria fluorescência ou de outras espécies de absorção, neste caso, são formados os complexos menos ou não fluorescentes (complexação de equilíbrio) (LAKOWICZ, 2006).

As SH possuem uma estrutura complexa formada por anéis aromáticos e grupos funcionais reativos que são responsáveis pela elevada capacidade de ligação com os metais, como cobre e alumínio. Assim, a sensibilidade e a simplicidade da Fluorescência de Quenching a torna viável, a fim de analisar as interações SH-metais [START_REF] Da | Fluorescence quenching of anthropogenic fulvic acids by Cu(II), Fe(III) and UO2/2+[END_REF]. Ryan e Weber (1982) propuseram a aplicação da fluorescência de quenching para medir propriedades complexantes da matéria orgânica natural e para definir a constante de instabilidade condicional e a capacidade de ligação dos íons metálicos. Luster et al. (1996), avaliando os diferentes comportamentos de análise da fluorescência de quenching, concluíram que há diferentes tipos de ligação do metal cobre com a MO, os quais são denominados de ligações fracas, ligações fortes e ligações de complexos muito fortes. Smith e Kramer (2000) propuseram um método multi-resposta para explicar todos os sítios de fluorescência disponíveis da ligação cobre-matéria orgânica. Segundo esses autores, foram identificados cinco diferentes componentes fluorescentes da matéria orgânica usando a técnica de resolução espectral.

Estudos realizados por Yamashita e Jaffe ( 2008), empregando análise de fator paralelo, apresentaram a contribuição de oito componentes que são responsáveis pela ligação entre cobre-matéria orgânica.

Desta forma, a análise de Fluorescência de Quenching tem sido estudada como uma fonte de informação sobre o que está acontecendo no nível molecular destes compostos (metal-matéria orgânica).

1.3.4.Espectroscopia de Infravermelho com transformada de Fourier

A espectroscopia de fluorescência com transformada de Fourier (FTIR) é uma técnica que permite a análise na região do infravermelho do espectro eletromagnético, sendo que os comprimentos de onda normalmente mais utilizados é o da região do infravermelho médio (4000 e 400 cm -1 ) (STEVENSON, 1994).

Na região do infravermelho a absorção é causada por movimentos rotacionais e vibracionais dos grupos moleculares e por ligações químicas de uma molécula. A absorção de radiação infravermelha provoca, portanto, aumento da amplitude das vibrações moleculares (LOPES & FACIO, 2004).

Existem duas vibrações fundamentais: estiramento, onde os átomos permanecem no mesmo eixo da ligação, porém, a distância entre os átomos aumenta e diminui, e, deformação, onde as posições dos átomos mudam em relação ao eixo de ligação original. Quando a luz infravermelha de mesma frequência de vibração de estiramento ou de deformação incide na amostra, a energia é absorvida e a amplitude de vibração é aumentada. Ocorrendo a absorção na frequência de ressonância, o detector do espectrômetro de infravermelho grava um pico de absorção naquele comprimento de onda (STEVENSON, 1994).

As vibrações de estiramento são mais energéticas e são absorvidas, portanto, em frequências superiores às das vibrações de deformação. Estiramentos de ligações envolvendo próton (OH, C-H e N-H) ocorrem em maiores frequências (3700 a 2650 cm -1 ) do que estiramentos de ligações do tipo C-C, C-O, e C-N (1300 a 800 cm-1) (STEVENSON, 1994).

Análises de FTIR fornecem informações úteis, pois permitem identificar possíveis processos de oxidação e alteração de grupos funcionais, associados aos efeitos de manejos, da mudança no pH, de complexação com micronutrientes provenientes de fertilizantes ou naturalmente ocorrendo no solo.

Nos estudos que envolvem a MOS e as SH, a Espectroscopia de Infravermelho apresenta-se útil, pois fornece o entendimento sobre a natureza, a reatividade e o arranjo estrutural de grupos funcionais contendo átomos de oxigênio, proteínas e carboidratos [START_REF] Bardy | Micromorphology and spectroscopic characteristics of organic matter in waterlogged podzols of the upper Amazon basin[END_REF][START_REF] Davis | QUANTITATIVE FOURIER TRANSFORM INFRARED SPECTROSCOPIC INVESTIGATION OF HUMIC SUBSTANCE FUNCTIONAL GROUP COMPOSITION[END_REF][START_REF] Monakhova | Independent component analysis and multivariate curve resolution to improve spectral interpretation of complex spectroscopic data sets: Application to infrared spectra of marine organic matter aggregates[END_REF]STEVENSON;[START_REF] Stevenson | Infrared spectra of humic acids and related substances[END_REF]. Os resultados dos espectros infravermelhos contém uma variedade de bandas que podem indicar diferentes grupos funcionais presentes nas misturas complexas (STEVENSON, 1994).

Capítulo 2. Distribution of soils in a small catchment in the upper Negro River basin -Brazilian Amazonia and the steps of transformation of a podzolized pedo-landscape Abstract: On the tablelands of the lower Negro River basin, clayey soils commonly occupy the highest topographic positions and podzols occupy the lowest ones. Studies showed that the more clayey soils are superimposed by podzols, which develop from downslope to upslope. However, in the extensive podzolized areas of the upper Negro River basin, thick podzols occupy the top of tabular hills and more clayey hydromorphic soils are found in the middle and downslope areas. The aim of this work was to understand this distribution, to describe the soil main morphological characteristics and to propose a genetic explanation for this last soil setting. This studied site was chosen from satellite images. Field works included four soil trenches description and sampling for physical and carbon content analysis, as well as the local topography survey. The incision of the drainage network on the previously podzolized parts of the plateaus generates a relief of hills with tabular tops with deep podzols and exposes, on the new elaborated slopes, the spodic horizons and the bleached and clayey saprolitic material of the eroded podzols. The perched groundwater supported by the spodic horizons, outwelling along the slope, creates water-saturated conditions in the surface horizons. The waters, loaded with dissolved organic acids, create podzolizing conditions, allowing the development of a second generation of podzols. The evolution of the catchment is closely linked to the installation of the drainage network and to the pedogenic processes. Keywords: landscape evolution; podzolization; drainage incision; Amazonia.

Introduction

In the central Amazon basin (Fig. 1a), soil studies have revealed that the most clayey soils occupy the edges of the basin and the less clayey soils are located in the center (Fig. 1b). They turn into sandy soils in the far NW [START_REF] Bueno | Appauvrissement et podzolisation des latérites du bassin du Rio Negro et gênese dês Podzols dans le haut bassin amazonien[END_REF]COSTA et al., 1977;[START_REF] Do | Podzolization as a deferralitization process: A study of an Acrisol-Podzol sequence derived from Palaeozoic sandstones in the northern upper Amazon Basin[END_REF][START_REF] Fritsch | From Plinthic Acrisols to Plinthosols and Gleysols: Iron and groundwater dynamics in the tertiary sediments of the upper Amazon basin[END_REF]YAMAZAKI;COSTA;AZEVEDO, 1978) (Fig. 1b). At the slope scale, studies have reported that the lateritic soils present in this basin are gradually podzolized towards the upslope (BRAVARD; [START_REF] Bravard | Podzols in Amazonia[END_REF][START_REF] Bueno | Appauvrissement et podzolisation des latérites du bassin du Rio Negro et gênese dês Podzols dans le haut bassin amazonien[END_REF]CHAUVEL;LUCAS;BOULET, 1987;[START_REF] Do | Podzolization as a deferralitization process: A study of an Acrisol-Podzol sequence derived from Palaeozoic sandstones in the northern upper Amazon Basin[END_REF][START_REF] Lucas | Systemes sols ferrallitiques -podzols en region amazonienne[END_REF]. The spatial distribution of these soils, as shown in Fig. 1b, allows the interpretation that these soils are progressively superimposed by podzols, with repercussions on the configuration of the Amazon pedo-landscape (BRAVARD; [START_REF] Bravard | Podzols in Amazonia[END_REF][START_REF] Bueno | Appauvrissement et podzolisation des latérites du bassin du Rio Negro et gênese dês Podzols dans le haut bassin amazonien[END_REF]CHAUVEL;LUCAS;BOULET, 1987;[START_REF] Do | Podzolization as a deferralitization process: A study of an Acrisol-Podzol sequence derived from Palaeozoic sandstones in the northern upper Amazon Basin[END_REF][START_REF] Dubroeucq | From Oxisols to Spodosols and Histosols: evolution of the soil mantles in the Rio Negro basin (Amazonia)[END_REF][START_REF] Dubroeucq | From Oxisols to Spodosols and Histosols: evolution of the soil mantles in the Rio Negro basin (Amazonia)[END_REF][START_REF] Lucas | SYSTEMES SOLS FERRALLITIQUES -PODZOLS EN REGION AMAZONIENNE[END_REF] . This superimposition results from the establishment of a depletion front by hydromorphy, mainly in iron [START_REF] Bueno | Appauvrissement et podzolisation des latérites du bassin du Rio Negro et gênese dês Podzols dans le haut bassin amazonien[END_REF][START_REF] Do | Podzolization as a deferralitization process: A study of an Acrisol-Podzol sequence derived from Palaeozoic sandstones in the northern upper Amazon Basin[END_REF][START_REF] Fritsch | Deciphering the weathering processes using environmental mineralogy and geochemistry: Towards an integrated model of laterite and podzol genesis in the Upper Amazon Basin Crystal chemistry of Al and Fe Kaolinite Fe-oxides Organo-metallic complexes Laterit[END_REF] and then in clay (BRAVARD; [START_REF] Bravard | Podzols in Amazonia[END_REF][START_REF] Bueno | Appauvrissement et podzolisation des latérites du bassin du Rio Negro et gênese dês Podzols dans le haut bassin amazonien[END_REF][START_REF] Do | Podzolization as a deferralitization process: A study of an Acrisol-Podzol sequence derived from Palaeozoic sandstones in the northern upper Amazon Basin[END_REF][START_REF] Lucas | SYSTEMES SOLS FERRALLITIQUES -PODZOLS EN REGION AMAZONIENNE[END_REF][START_REF] Lucas | Systemes sols ferrallitiques -podzols en region amazonienne[END_REF]. The depletion of clay promotes the development of porosity in-between the quartz grains (FRITSCH et al., 1989) which in turn allows organic acids and soluble organic matter to leach through the soil horizons, accumulating in the deeper horizons or moving towards the rivers [START_REF] Bardy | Micromorphology and spectroscopic characteristics of organic matter in waterlogged podzols of the upper Amazon basin[END_REF]BRAVARD;[START_REF] Bravard | Podzols in Amazonia[END_REF][START_REF] Do | Podzolization as a deferralitization process: A study of an Acrisol-Podzol sequence derived from Palaeozoic sandstones in the northern upper Amazon Basin[END_REF][START_REF] Fritsch | Organic complexation and translocation of ferric iron in podzols of the Negro River watershed. Separation of secondary Fe species from Al species[END_REF].Consequently, the podzols are formed.

Thus, the organic matter mobilizes complexed aluminum and iron that are derived from the dissolution of clays and iron oxides [START_REF] Do | Podzolization as a deferralitization process: A study of an Acrisol-Podzol sequence derived from Palaeozoic sandstones in the northern upper Amazon Basin[END_REF][START_REF] Lucas | Genèse et fonctionnement des sols en milieu équatorial[END_REF] LUNDSTRÖM; [START_REF] Lundström | The podzolization process. A review[END_REF][START_REF] Lundström | The podzolization process. A review[END_REF]. Extensive podzolized areas then constitute the final state of evolution of the soils on the tablelands of equatorial landscapes (DUBROEUCQ; VOLKOFF, 1998). In the Negro River basin, the podzols are located on the low tablelands, connected or unconnected to the main drainage system. Podzols are distributed over depressed areas along the plateau interfluves, thus partially connected to the drainage system (for example at the Jaú River basin, at the middle to lower Negro River basin), (BUENO; DO NASCIMENTO, 2002;[START_REF] Do | Podzolization as a deferralitization process: A study of an Acrisol-Podzol sequence derived from Palaeozoic sandstones in the northern upper Amazon Basin[END_REF] or fully connected to the main drainage system, for example in the upper Negro River basin at the Curicuriari River basin, in the municipality of São Gabriel da Cachoeira [START_REF] Bueno | Appauvrissement et podzolisation des latérites du bassin du Rio Negro et gênese dês Podzols dans le haut bassin amazonien[END_REF] or at the base of slopes in the Manaus region, at the lower Negro River basin [START_REF] Lucas | SYSTEMES SOLS FERRALLITIQUES -PODZOLS EN REGION AMAZONIENNE[END_REF],on the slopes located at the contact areas between clayey soils and the podzols, at the regional scale, the clayey soils typically occupy the highest sections, while the podzols occupy the low sections from where they progress in the upslope direction (BRAVARD; [START_REF] Bravard | Podzols in Amazonia[END_REF][START_REF] Do | Podzolization as a deferralitization process: A study of an Acrisol-Podzol sequence derived from Palaeozoic sandstones in the northern upper Amazon Basin[END_REF][START_REF] Lucas | SYSTEMES SOLS FERRALLITIQUES -PODZOLS EN REGION AMAZONIENNE[END_REF]. However, in various areas of the upper Negro River basin, there is a different spatial distribution of the podzolized soils and the clayey soils at the slope scale. Thick podzols occupy the tops of tabular hills and more clayey soils (gleysols) are found in the middle and lower portions of slopes (DUBROEUCQ; [START_REF] Dubroeucq | From Oxisols to Spodosols and Histosols: evolution of the soil mantles in the Rio Negro basin (Amazonia)[END_REF]. This configuration is explained by the incision of the drainage network on the podzolized edges of the plateau, generating a relief of tabular hilltops with deep podzols and exposing, on new slopes, the more clayey materials derived from the saprolites (BUENO; DO NASCIMENTO; [START_REF] Fritsch | From Plinthic Acrisols to Plinthosols and Gleysols: Iron and groundwater dynamics in the tertiary sediments of the upper Amazon basin[END_REF][START_REF] Fritsch | Deciphering the weathering processes using environmental mineralogy and geochemistry: Towards an integrated model of laterite and podzol genesis in the Upper Amazon Basin Crystal chemistry of Al and Fe Kaolinite Fe-oxides Organo-metallic complexes Laterit[END_REF]. A new pedogenesis is then initiated on these materials. This study, therefore, examines the spatial distribution and characteristics of the podzols and the more clayey soils (gleysols) at the small catchment scale and present the steps of the pedo-landscape transformation.

Regional setting

The study site (latitude 0° 14' S and longitude 66° 47' W) is located in the municipality of São Gabriel da Cachoeira, Amazonas state (AM), Brazil, approximately 850 km away from Manaus (Figure 1). It is a small catchment (1 ha) and the main stream is characterized by dark, blackish-brown waters that flow into another small stream with clear, colorless waters (Figure 1c). The dark waters mix with the clear water stream over a distance of 10 m. This configuration indicates pedo-landscape compartments with different soil systems.

The climate is hot and humid. According to the W. Köppen classification , the site is in the Af zone (tropical rainforest), with mean annual temperatures of approximately 25ºC and mean annual rainfall totals of approximately 3 000 mm. Rainfall peaks during March, April, May, and June and less rain falls from September to November (COSTA et al., 1977).

Regionally, the study area lies at the contact between two types of vegetation covers: the Terra Firme Forest and the Forested Campinarana (white sand forest, with trees whose trunks are thinner in comparison with the trees of Terra Firme Forest). Forested Campinarana areas predominate to the W and SW of São Gabriel da Cachoeira on undulating or tabular reliefs, while Terra Firme Forest predominates to the N, E, and SE of this city on dissected or undulating reliefs. The study area is located in a Forest/Edaphic Formation contact area (Campinarana), with a prevalence of Submontane Dense Forest (Terra Firme Forest) on a dissected relief (SILVA; JESUS; RIBEIRO, 1977).

Under these vegetal covers, the Low Amazon Plateau is formed by low-altitude tableland reliefs that constitute broad interfluves and exhibit altimetric homogeneity (tabular interfluves and hills between 80 and 100 m a.s.l) (FRANCO; MOREIRA; BARBOSA, 1977). The base of the relief consists of rocks from the crystalline basement. These rocks belong to the Guianian Complex, which comprises gneisses, migmatites, granites, granodiorites, and amphibolites of ages ranging between 1300 and 1400 million years (FERNANDES et al., 1977).

Materials and methods

2.3.1.Site identification and selection, field work, soil study, and sampling

Orbital image interpretations were used for the selection of a potential study area. The analysis of the image texture guided the delineation of areas with Dense Forest and Forested Campinarana.

The first vegetation type is associated with lateritic soils and the latter with podzolized soils. Within this area, a small catchment was selected during the field work and four trenches were excavated for detailed soil analysis. The choice of sites for the trenches opening was based on the pedo-topographic mapping of the catchment (Figure 2.2). The trenches were opened heading downslope from the top of the slope to a small stream thalweg of blackish waters (Figure 2.2). The soils of the four trenches were characterized using procedures adapted from the Structural Analysis of Soil Cover [START_REF] Boulet | Analyse structurale et cartographie en pédologie 1 -Prise en compte de l'organisation bidimensionnelle de la couverture p8dologique μ les Etudes de toposéquences et leurs principaux apports A la connaissance des sols[END_REF] and classified according to FAO (2006).

The profiles were described in terms of color, texture, structure, consistence and the transitions between horizons. Seventeen soil samples were collected during the low-water period (November 2010), air-dried, crushed, sieved through 2-mm, and quartered and subdivided into aliquots to be used in laboratory analyses.

2.3.2.Pedo-topographic mapping

A rectangular grid of 99 points was projected onto the study area. These points were spread over nine parallel tracks in the NE-SW direction and 11 parallel tracks in the NW-SE direction. The interval between the points was 15 m. The topographic survey was conducted with the use of a clinometer. The geographic coordinates were collected at by GPS the intersection points. The data from each point were entered into the ArcGis 9.3 software and interpolated by kriging. Allowing for the reconstitution of the topography. At each point of intersection of the tracks, soil auger borings were performed for the assessment and quick description of the soil horizons. Using the auger borings and the observations of the changes in relief and vegetation, the boundaries between the soil types were established.

2.3.3.Laboratory procedures: particle size and carbon contents

The texture analysis was conducted according to the modified pipette method by [START_REF] Camargo | Métodos de análise química, mineralógica e física de solos do Instituto Agronômico de Campinas[END_REF]. This analysis aimed to verify the changes in texture among the profiles and the delineation of various particle-size-distribution centers. The following intervals were considered: coarse sand (2.00 -0.20 mm); fine sand (0.20 -0.05 mm); silt (0.05 -0.002 mm), and clay (< 0.002 mm).

The determination of total C was performed using the dry combustion technique on 17 clay samples obtained from separation by density difference of particles, with no prior processing. The amount of C was quantified by gas chromatography after conversion into CO2 and reported as a percentage in mass.

Results

Soil coverage and groundwater levels

The grid of described and sampled points allowed the preparation of the map presented in To the north of the catchment, a podzol with a thick E horizon of white sand and hardened, spodic horizons below 150 cm in depth occupy the highest portion of the slope (Figure 2.2). These spodic horizons support a perched water table, with black waters. Moving down the slope, the E horizon of white sand (situated on top of the hard spodic horizons) decreases in thickness and, consequently, the level of the perched water table approaches the surface. For this reason, the soils there were characterized as hydromorphic podzols. Even further down the slope, the E horizon of white sand disappears and the spodic horizons are only a few centimeters deep and transition upwards directly into the A horizon. These spodic horizons are less hardened than those of the upslope soils.

The perched water table springs on the surface. Below these spodic horizons, after an unsaturated layer, there is a second groundwater table. This groundwater level shows a lateral continuity with the only groundwater level found at depth in the gleysol, located at the margin and outside of the catchment area in the W and E portions of the map (Figure 2.2).

Soil distribution along the slope

The soil profiles of four trenches aligned in the NW-SE and NE-SW directions, represented on the pedo-topographic map as black circles (Figure 2.2), were described. On the map, the black solid line represents a cross-section on which the described soil profiles are schematically represented. This cross-section was divided into A-B-C and C-D sections (Figure 2.3) that together represent two soil systems: podzolized and hydromorphic.

The thick (150 + cm) podzol under the forested Campinarana vegetation has well-drained and sandy horizons (Figures 2 and3a). A thin layer of litter is present on top of the 13-cm-thick A horizon, the color of which is a very dark gray (2.5Y 3/1) and the structure of which is weakly granular in association with the loose quartz grains and organic matter granules. This horizon gradually transitions into the horizon below, which has a thickness of 32 cm and is recognized as an AE horizon.

The structure remains the same but the proportion of simple white sand grains increases and the proportion of organic matter granules decreases. The gray color (2.5Y 5/1) corresponds to the areas of higher organic content in the horizon. In the lower horizon (28 cm thick), organic granules are scarce and are distributed over somewhat vertically elongated zones, while the color is lighter (2.5Y 6/1) and juxtaposed to the white color of the less organic and more quartzitic domains. This horizon, known as E1, becomes the E2 horizon (80 cm) because of the generalization of the simple grain structure and the white color of the quartzitic sand. The higher organic content zones are scarce and restricted to a few areas. This horizon sharply transitions into the next lower horizon. It is a Bh horizon that begins 153 cm below the surface but could not be prospected throughout its entire thickness because of the landslides at the trench walls associated with the presence of groundwater. The horizon structure is blocky; its black color (2.5Y 2.5/1) reveals that the organic matter is distributed more homogeneously over the quartz grains; however, the black color is permeated by white quartz sand grains that are observed in association with pores and roots.

The profile of the hydromorphic podzol that has developed under the forested campinarana vegetation (Figures 2 and3a) has moderately thick litter layer on top. The A horizon (20 cm) has a granular structure and a very dark gray color (2.5Y 3/1) that is linked to the mor-humus organic matter (Duchaufour, 1960). This horizon gradually yields to an AE horizon (22 cm) with a lighter, more heterogeneous color, tending towards brown and light brownish gray (2.5Y 6/2). The structure of this horizon is composed of loose grains that are associated with organic matter granules. This AE horizon becomes gradually lighter until transitioning into the white (2.5Y 8/1) E1 horizon, which is 45 cm thick with a structure that is composed of loose grains and sparse organic matter granules. This horizon abruptly changes to the Bh horizon at a depth of 97 cm. The color of the Bh is black (2.5Y 2.5/1), and organic matter covers the grains; it has a weakly blocky structure. A perched water table is located above the Bh horizon (67 cm deep on 24/June/2010).

The cryptopodzol, (in the sense of Duchaufour, 1972) (Figures 2.2 and 2.3a, b) is located in a forested campinarana/terra firme forest transition area (Figure 2.2). The A horizon (22 cm thick) is preceded by a thick litter layer. The structure of the A horizon is granular and the color is black (2.5Y 2.5/1); the organic matter is mor humus. This horizon gradually transitions into a Bh3 horizon (12cm thick) that is characterized by a loose grain structure and a dark gray color (5Y 4/1). The gray color gradually lightens (2.5Y 5/1) and there are white sand streaks at 19 cm. This horizon was called Bh2, and its structure is formed by loose grains. The lower horizon was named E/Bh; it is 19 cm thick, has a loose grain structure, and contains grayish spots (5Y 6/1). There is a sharp transition at 72 cm to the CBhs horizon, which is composed of a highly friable, massive structure. This CBhs horizon contains relics of slightly altered primary minerals (mainly muscovite micas) and is strongly impregnated with organic matter, which contributes to the very dark grayish brown color (5Y 3/2) of the horizon. Groundwater is found at 60 cm.

The gleysol, also located in the forested campinarana/terra firme forest transition range (Figure 2.3b), has a thick litter layer over the A horizon. This A horizon (11cm thick) is dark olive brown (2.5Y 3/3), sandy, and granular. The organic matter is of the moder humus type (duchaufour, 1960). This horizon gradually transitions into the lower Bhs horizon (23 cm), with a small granular structure, olive gray color (5Y 5/2), and sandy loam texture. The transition to the lower horizon (Cg1) is clear. This horizon (34-64 cm) has a light olive gray color (5Y 6/2) with some brown spots, a sandy loam texture, and a massive structure with remnants of minerals yet to be decomposed. Gradually, across a diffuse transition, the Cg1 becomes a Cg2 horizon that is 20+ cm thick. The texture of the Cg2 is sandy loam and primary minerals are more abundant. The structure is massive and the color is light gray (5Y 7/1). Groundwater was present at a depth of 80 cm on 06/24/2010. 

2.4.3.Variation of texture classes and carbon in soil profiles

The textures of the soil profiles are presented in figure 4. It is evident that the upslope soils are sandy and that the proportion of clay increases downslope. The thick podzol and the hydromorphic podzol consist of greater than 95% sand in all horizons, revealing profiles that are strongly depleted in clay (from 0 to 4.3%). The hydromorphic podzol is the least clayey soil, although its Bh horizon has the largest amount of clay of these two soil profiles (4.3%) (Figure 2.4). In the cryptopodzol, the surface horizons and the EBh horizon are characterized by sand percentages greater than 90%, while the clay percentage ranges from 0.35 to 5.5% in these same horizons (Figure 2.4). In contrast, the CBhs horizon has a clay content of 22.05%. The gleysol is the most clayey soil of the transect; the sand content is less than 85% (Figure 4), while the clay content ranges from 13.15% in the A horizon to 17.05% in the Cg1 horizon. The texture triangles of the four studied profiles, shown in figure 2.4, reveal 3 texture groups. The thick podzol and the hydromorphic podzol have high surface C contents (50.45 and 58.92%) that strongly decrease in the E horizon (10.06 and 16.31%) and then increase in the Bh horizon (38.4% and 29.14%). The C contents of the cryptopodzol are generally higher than those of the upslope podzols. For the cryptopodzol, the C content ranges from 52.28% in the A horizon to 10.49% in the CBhs horizon, revealing a decreasing trend in the C content towards the base of the profile. This trend therefore reveals that the process of podzolization is in its initial stage and highlights the difference between this profile and the preceding soil profiles. The gleysol contains less carbon than the all profiles. There is a decreasing trend with depth (14.04 to 3.38%). This trend suggests that the nature of organic matter in this profile is different from the other profiles because, in contrast to the podzols and cryptopodzol, there is no accumulation of organic matter in the deeper in the E horizon, accumulating in the hydromorphic podzol Bh horizon and mobilizing and accumulating further downslope in the cryptopodzol. In the latter, however, dissolution and mobilization occur in a discrete manner, forming the E/Bh horizon.

All of the soil profile horizons of the concave segment are consistent with the topographic surface of this concave segment and are parallel to each other and to the surface, denoting the vertical differentiation of these horizons over the same source material, i.e., from the rock alteration horizon.

This fact reveals the existence of a new podzolization phase that differs from the one that originated the thick podzol. [START_REF] Bueno | Appauvrissement et podzolisation des latérites du bassin du Rio Negro et gênese dês Podzols dans le haut bassin amazonien[END_REF] also identified this new podzolization phase in a study in the Curicuriari River basin -AM.

Figure 2.3b shows that the slope opposite to the first slope contains slightly convex and rectilinear segments. In the rectilinear and convex segments, the gleysol profile is 1 m below the top level of the thick podzol, while the cryptopodzol is located 3.5 m below the top gleysol level.

Although the difference in height between the thick podzol and the gleysol is small, it reflects the impact of the drainage incision that exposed the hydromorphized alteration horizons of the rock. The difference in height between the gleysol and cryptopodzol reveals the greater depth of the relief and reaffirms the resumption of podzolization on the hydromorphic alteration of the rock, that is, on the horizons of alteration materials of ancient lateritic formations. This type of development has also been suggested by [START_REF] Bueno | Appauvrissement et podzolisation des latérites du bassin du Rio Negro et gênese dês Podzols dans le haut bassin amazonien[END_REF] and [START_REF] Bueno | Considerações acerca da evolução dos relevos nas paisagens podzolizadas da bacia do Rio Negro-AM. (IX Encontro nacional da associação nacional de pós-graduação e pesquisa em Geografia[END_REF]. The development of the gleysols that are located on the edge of the podzolized plateaus is possible because of the exposure of saprolite when there is a dissection of the plateau, the erosion of the podzols, and the outwelling of the groundwater and of the Bh horizon, according to [START_REF] Bueno | Appauvrissement et podzolisation des latérites du bassin du Rio Negro et gênese dês Podzols dans le haut bassin amazonien[END_REF] and [START_REF] Bueno | Considerações acerca da evolução dos relevos nas paisagens podzolizadas da bacia do Rio Negro-AM. (IX Encontro nacional da associação nacional de pós-graduação e pesquisa em Geografia[END_REF]. [START_REF] Fritsch | From Plinthic Acrisols to Plinthosols and Gleysols: Iron and groundwater dynamics in the tertiary sediments of the upper Amazon basin[END_REF] have reported that such hydromorphic systems can occur in three locations in the Amazonian landscape: in floodplains, in the depressions of the plateaus, and at the edges of the more podzolized plateaus. In the podzolized zones, this hydromorphism is linked to the bleaching of old lateritic formations by the constant presence of water [START_REF] Fritsch | From Plinthic Acrisols to Plinthosols and Gleysols: Iron and groundwater dynamics in the tertiary sediments of the upper Amazon basin[END_REF].

Figure 2.4, reveal the difference between a more eluviated area (thick podzol and hydromorphic podzol) and a less eluviated area (cryptopodzol and gleysol), with greater accumulations of carbon in most of the cryptopodzol horizons and lower accumulations of carbon in the gleysol horizons (Table 1), an indication that hydromorphy is most severe in the cryptopodzol, hindering the decomposition of organic matter that is incorporated into the soil. Except for the cryptopodzol CBhs horizon, in figures 4c and d, the two different textural areas are opposites and correspond to a clayey extreme upslope and a sandy extreme downslope in figure 3b. The clayey extreme (gleysol) gradually becomes sandy (cryptopodzol). This trend is opposite to the carbon accumulation trend in the cryptopodzol horizons, indicating that the superimposition of organic matter on the gleysol structures occurs after its depletion in clay. Turenne (1977) and [START_REF] Lucas | SYSTEMES SOLS FERRALLITIQUES -PODZOLS EN REGION AMAZONIENNE[END_REF] noted this depletion of clay in soils in the pre-podzolization phase and recognized that this process is an essential precondition for podzolization because it allows the percolation of organic matter through the profiles. This depletion of clay increases the development of macropores among the quartz grains [START_REF] Fritsch | From Plinthic Acrisols to Plinthosols and Gleysols: Iron and groundwater dynamics in the tertiary sediments of the upper Amazon basin[END_REF]which enables the percolation of organic matter through the profile.

The pedo-morphology of segments B-C and C-D of the slopes are complementary and juxtaposed. The two segments can be joined because they are connected through the low-depth suspended groundwater table to the drainage of the stream of blackish waters, while the thick and hydromorphic podzols are not connected to this stream through the perched groundwater table.

Therefore, the thick and hydromorphic podzols are open to the main drainage and suspended in relation to the current incision. The current incision certainly influences the evolution of a new podzolization phase (in a more hydromorphic environment), in which the mineralization of organic matter is decelerated and C cycling slows.

Modification steps of the pedo-landscape throughout the soil transformation

The strong depletion of clay from lateritic soils by several processes during the development of podzolization has been extensively described for the Amazon (BRAVARD; [START_REF] Bravard | Podzols in Amazonia[END_REF][START_REF] Bueno | Appauvrissement et podzolisation des latérites du bassin du Rio Negro et gênese dês Podzols dans le haut bassin amazonien[END_REF][START_REF] Bueno | Appauvrissement et podzolisation des latérites du bassin du Rio Negro et gênese dês Podzols dans le haut bassin amazonien[END_REF]DO NASCIMENTO, 2002;[START_REF] Do | Podzolization as a deferralitization process: A study of an Acrisol-Podzol sequence derived from Palaeozoic sandstones in the northern upper Amazon Basin[END_REF], 2008;[START_REF] Dubroeucq | From Oxisols to Spodosols and Histosols: evolution of the soil mantles in the Rio Negro basin (Amazonia)[END_REF][START_REF] Dubroeucq | From Oxisols to Spodosols and Histosols: evolution of the soil mantles in the Rio Negro basin (Amazonia)[END_REF][START_REF] Fritsch | Organic complexation and translocation of ferric iron in podzols of the Negro River watershed. Separation of secondary Fe species from Al species[END_REF][START_REF] Lucas | SYSTEMES SOLS FERRALLITIQUES -PODZOLS EN REGION AMAZONIENNE[END_REF]. In these cases, the podzolization of plateau centers always advances upwards along the slopes, either from depressed zones with hydromorphic podzols [START_REF] Bueno | Appauvrissement et podzolisation des latérites du bassin du Rio Negro et gênese dês Podzols dans le haut bassin amazonien[END_REF][START_REF] Bueno | Appauvrissement et podzolisation des latérites du bassin du Rio Negro et gênese dês Podzols dans le haut bassin amazonien[END_REF]DO NASCIMENTO, 2002;[START_REF] Do | Podzolization as a deferralitization process: A study of an Acrisol-Podzol sequence derived from Palaeozoic sandstones in the northern upper Amazon Basin[END_REF][START_REF] Dubroeucq | From Oxisols to Spodosols and Histosols: evolution of the soil mantles in the Rio Negro basin (Amazonia)[END_REF][START_REF] Dubroeucq | From Oxisols to Spodosols and Histosols: evolution of the soil mantles in the Rio Negro basin (Amazonia)[END_REF][START_REF] Fritsch | Deciphering the weathering processes using environmental mineralogy and geochemistry: Towards an integrated model of laterite and podzol genesis in the Upper Amazon Basin Crystal chemistry of Al and Fe Kaolinite Fe-oxides Organo-metallic complexes Laterit[END_REF] or from the bases of slopes that are already connected to a drainage network (BRAVARD; [START_REF] Bravard | Podzols in Amazonia[END_REF][START_REF] Bueno | Appauvrissement et podzolisation des latérites du bassin du Rio Negro et gênese dês Podzols dans le haut bassin amazonien[END_REF][START_REF] Fritsch | Deciphering the weathering processes using environmental mineralogy and geochemistry: Towards an integrated model of laterite and podzol genesis in the Upper Amazon Basin Crystal chemistry of Al and Fe Kaolinite Fe-oxides Organo-metallic complexes Laterit[END_REF][START_REF] Lucas | SYSTEMES SOLS FERRALLITIQUES -PODZOLS EN REGION AMAZONIENNE[END_REF]). In the study presented herein, the podzolization of the more clayey soils (gleysols), which originated from the pedogenesis of saprolite exposed after the drainage incision, occurs from flows of solutions containing dissolved organic acids from the podzols located at the top of the slope. It is, therefore, a podzolization by superimposition, from upslope to downslope.

In the studied catchment, the evolution of the pedo-landscape was sufficient to cause the plateau shape to disappear, but left indicators of that previous form and establish the soil connections between The descriptive model presented in figure 2.5, based on the spatial distribution of the soils (Figure 2.2) and the characterization of the soils on the slope (Figure 2.3), represents the synthesis of this evolution.

A) The low-altitude plateau with low gradient slopes is characterized by the thick podzol soil.

This plateau is open to the main drainage and is beginning to be truncated by the erosion that results from the installation of incipient drainage in the center of the plateau.

B) The truncation of the podzol of the top from the edge of the incipient thalweg enables the occurrence of the perched water table near the soil surface, causing water supersaturation. Meanwhile, hydromorphic saprolite outcrops in the valley slopes.

C) The gleysol is formed from the differentiation of soil horizons on the hydromorphic saprolite.

D) The cryptopodzol is formed by the superimposition of dissolved acid organic matter on the gleysol, which is already depleted in clay.

57 while for condensation and aromaticity of the HA, the greater porosity is, the temporary visit of the water in the horizons is fundamental.

Keywords: humic substances, podzolization, pedoenviroments, Amazonian.

Introduction

In the Amazon forest, the Upper Rio Negro basin is prominent due to its primary pedological formations consisting of podzols, oxisols and hydromorphic soils [START_REF] Do | Podzolization as a deferralitization process: A study of an Acrisol-Podzol sequence derived from Palaeozoic sandstones in the northern upper Amazon Basin[END_REF][START_REF] Fritsch | Deciphering the weathering processes using environmental mineralogy and geochemistry: Towards an integrated model of laterite and podzol genesis in the Upper Amazon Basin Crystal chemistry of Al and Fe Kaolinite Fe-oxides Organo-metallic complexes Laterit[END_REF].

The pedogenic process involved in podzol soil formation is known as podzolization; the primary mechanism in the genesis of these soils is called acid complexolysis and occurs in acidic environments with a pH between 3 and 5 (BUURMAN; JONGMANS, 2005; LUNDSTRÖM; [START_REF] Lundström | The podzolization process. A review[END_REF][START_REF] Lundström | The podzolization process. A review[END_REF]. Organic acids, formed by the decomposition of organic matter (OM) accumulated in the soil surface. Podzolization indicates the presence of OM that favors the formation of organo-metallic complexes composed of Fe and Al and the translocation and accumulation of part of this organic matter in the deep horizons (Bh) (BUURMAN; JONGMANS, 2005; LUNDSTRÖM; [START_REF] Lundström | The podzolization process. A review[END_REF][START_REF] Lundström | The podzolization process. A review[END_REF]. In regions with high precipitation, such as the Rio Negro basin, the acidic OM is mobilized through the clay-depleted soils (Acrisols) due to their high porosity which transforms them into podzols (BRAVARD; [START_REF] Bravard | Podzols in Amazonia[END_REF][START_REF] Grimm | Continuous multiligand mistribution model used to predict the stability constant of Cu(II) metal complexation with humic material from fluorescence quenching data[END_REF][START_REF] Do | Podzolization as a deferralitization process: A study of an Acrisol-Podzol sequence derived from Palaeozoic sandstones in the northern upper Amazon Basin[END_REF], 2008;[START_REF] Dubroeucq | From Oxisols to Spodosols and Histosols: evolution of the soil mantles in the Rio Negro basin (Amazonia)[END_REF][START_REF] Dubroeucq | From Oxisols to Spodosols and Histosols: evolution of the soil mantles in the Rio Negro basin (Amazonia)[END_REF][START_REF] Klinge | Podzol soils in the Amazon Basin[END_REF][START_REF] Lucas | Systemes sols ferrallitiques -podzols en region amazonienne[END_REF].This OM is transferred to the drainage nets and causes dark water coloration [START_REF] Bardy | Podzolisation and exportation of organic matter in black waters of the Rio Negro (upper Amazon basin, Brazil)[END_REF].

The soil organic matter (SOM) is the result of a complex mixture of organic residues (animals and Several studies focus on understanding the dynamics of the transformation of Amazonian Oxisols into Podzols (BRAVARD; [START_REF] Bravard | Podzols in Amazonia[END_REF][START_REF] Grimm | Continuous multiligand mistribution model used to predict the stability constant of Cu(II) metal complexation with humic material from fluorescence quenching data[END_REF][START_REF] Do | Podzolization as a deferralitization process: A study of an Acrisol-Podzol sequence derived from Palaeozoic sandstones in the northern upper Amazon Basin[END_REF], 2008;[START_REF] Dubroeucq | From Oxisols to Spodosols and Histosols: evolution of the soil mantles in the Rio Negro basin (Amazonia)[END_REF][START_REF] Dubroeucq | From Oxisols to Spodosols and Histosols: evolution of the soil mantles in the Rio Negro basin (Amazonia)[END_REF][START_REF] Klinge | Podzol soils in the Amazon Basin[END_REF][START_REF] Lucas | Systemes sols ferrallitiques -podzols en region amazonienne[END_REF] Among them, the work done by [START_REF] Bravard | Podzols in Amazonia[END_REF][START_REF] Grimm | Continuous multiligand mistribution model used to predict the stability constant of Cu(II) metal complexation with humic material from fluorescence quenching data[END_REF] on the FA and HA organic horizon fractions of an oxisolpodzol system is particularly significant. They found biochemical differences in the HS between the podzols and oxisols. The oxisol FA and HA are more aliphatic in the A1 horizons and have higher percentages of nitrogen [START_REF] Bardy | Micromorphology and spectroscopic characteristics of organic matter in waterlogged podzols of the upper Amazon basin[END_REF] analyzed the SOM of a clay-depleted-laterite(oxisol)podzol system in the lower Negro River basin (Jaú-AM) using micromorphological and spectroscopic measurements of the organic matter in the soil clay fraction. These results showed that the primary functional groups of SOM are the aliphatic, aromatic and oxygenated groups, and they highlighted the differences between the organic horizons of the soil systems.

The spectroscopic techniques most often used are UV-Visible absorption spectroscopy (UV-Vis) and Fourier Transform InfraRed spectroscopy (FTIR). UV-Vis identifies the π electron transitions of conjugated double bonds, such as those present in humic substances, and it is a useful technique for determining absorbance ratios that are related to the humification degree of aromatic and aliphatic structures (CHEN;SENESI;[START_REF] Chen | Information Provided on Humic Substances by E4/E6 Ratios[END_REF]. FTIR is often used for OM and HS characterization, wavenumber analysis between 4000 cm -1 and 400 cm -1 (STEVENSON, 1994) and for the identification of functional groups occurring in the organic components.

Thus, the present study aims to characterize FA and HA extracted using UV-Vis and FTIR spectroscopy from three podzolized soil profiles in the Upper Rio Negro basin under different states of podzolization in the, trying to understand the FA and HA distribution rules in sequencing soil throughout a hillside as well as horizons along with soil profiling. For such it will be conducted an analysis of the results obtained from spectroscopic methods relating them with soil morphology, texture, porosity, soil pH, total C, and groundwater dynamics among soil horizons.

Materials and methods

3.2.1.Environmental setting

The investigated site is located in the Upper Rio Negro basin at latitude 0° 14' S and longitude 67° 47' W in the municipality of São Gabriel da Cachoeira -AM (Figure 3.1A). The climate is typically equatorial with an average temperature of 26 °C and an annual average rainfall of 3000 mm without a well-defined dry season (COSTA et al., 1977).

Even if difference in rainfall is relative small between dry and humid periods, this type of change interfers specially within the fluctuation dynamics of the groundwater throughout the year (Figure 3.2) The geological substrate is composed of crystalline rocks with compositions varying between monzogranite, syenogranite and monzonitic quartz (AGNOL; MACAMBIRA, 1992). A selected soil sequence has profiles that belong to the podzolization system. This sequence is approximately 75 m in length and located in a micro-basin with a primary stream containing colored water. A detailed description of the basin was reported in the Chapter 2. Three soil profiles were studied in this micro basin on a rectilinear-convex-concave hillslope from the high slope to the low slope. Located on the high slope, a thick podzol named profile 1 (P1) (Figure 3.1B) has more than 150 cm thickness. It is followed by a hydromorphic podzol named profile 2 (P2) (Figure 3 

Extraction and fractionation of Humic Substances

The procedure of extraction and fractionation of the humic substances was performed using the principle of solubility difference established by the International Society of Humic Substances (PERDUE; PERDUE, 2012). Air dried soil samples were weighed (4 g) and mixed with 40 mL of 1 mol/L -1 HCl; the solution was stirred for one hour and then centrifuged at 1,500 rpm (g = 433 m.s -2 ).

The supernatant was discarded and 40 mL of 1 mol/L -1 NaOH was added to the solid, stirred for 4 hours and rested for 12 h. After the resting period, the solid was retired and the supernatant was acidified with 6 mol/L -1 HCl until a pH = 1.0 was achieved (<1 mL), and an additional 12 h rest period was applied. Subsequently, the solution was centrifuged at 10,000 rpm (g = 11,180 m.s -2 ) to separate the supernatant that contains FA and the precipitant that contains HA. The solid HA fraction was dissolved with 0.1 mol/L -1 NaOH and filtered using a polyethersulfone filter (Merck-Hydrophilic Nylon Membrane Filter with 0.2 m pore size) to remove the silica and clay remaining in the solution.

After filtration, the HA was transferred into a dialysis membrane (Sigma Aldrich avg. diam. 27 mm, avg. flat width 43 mm, capacity ~ 175 mL / ft and weight cut-off = 14,000 D). Dialysis was performed using deionized water until the water achieved a negative test for chloride ions (Cl-). The supernatant (FA) was first purified using a DAX-8 resin in sequence with an exchanging ion resin saturated with H + ions (Amberlite). Finally, the HA and FA samples were sent to lyophilization (Thermo electron Heto PowerDry LL 1500) and stored in glass flasks for analysis. At the end of the extraction and purification procedure, 36 powder samples were obtained.

Particle size analysis and pH

Granulometric analysis was performed according to the pipette method modified by [START_REF] Camargo | Métodos de análise química, mineralógica e física de solos do Instituto Agronômico de Campinas[END_REF]. The analysis determines the percentages of the coarse sand (2.00-0.20 mm), fine sand (0.020-0.05 mm), silt (0.05-0.002 mm) and clay (<0.002 mm) particles in the soil.

The pH of the soil samples were measured following the protocol proposed by EMBRAPA (EMBRAPA, 1997): 10 mg of soil was added in a plastic beaker with 25 mL of deionized H 2 O, and the pHH2O was recorded after 1 hour of standing.

3.2.5.Carbon Analysis

The determination of total soil organic carbon (TC) was performed using the dry combustion technique because carbonate is absent in Upper Rio Negro soils. The measurement was taken directly from the 18 dried and sieved soil samples and from the 36 extracted organic matter solid powder samples. The amount of TC was determined using gas chromatography after transformation into CO (Shimadzu TOC-5000A Analyzer) and reported in mass percent (%C).

Spectroscopic analyses

Absorbance measurements of the 36 HS samples were performed in a 1 cm quartz cuvette.

The FA and HA were dissolved in a 0.05 mol/L -1 NaHCO3 solution at a 20 ppm matter concentration and adjusted to a pH = 8.0. The UV-Vis absorbance was measured between 200 and 800 nm using a Shimadzu UV-1800. Natural organic matter UV-Vis measurements exhibit spectra that decay exponentially with wavelength (BIRDWELL; ENGEL, 2010a). The determined parameters are the absorbance ratios E2/E3 (ratio absorbance at 250 and 365 nm) and E4/E6 (ratio absorbance at 465 and 665 nm). E2/E3 ratio evaluates the aromaticity and molecular size of the humic substances [START_REF] Chen | Spectroscopic Characterization of Structural and Functional Properties of Natural Organic Matter Fractions Jie Chen[END_REF][START_REF] Mcdonald | Analytical chemistry of freshwater humic substances[END_REF]PEURAVUORI;[START_REF] Peuravuori | Molecular size distribution and spectroscopic properties of aquatic humic substances[END_REF]. A low E2/E3 ratio reflects a high average molecular weight, while E4/E6 is inversely related to the degree of condensation (STEVENSON,1994).

The FTIR spectra of the extracted SH were acquired in absorbance mode for only 32 samples

(2 FA and 2 HA samples were not measurable) using the Diamond Point Thermo Scientific IS50-FT-IR equipment. The results were determined in the range of 4,000 cm-¹ to 400 cm-¹ with a resolution of 4 cm -¹. A baseline correction was performed, and the spectra area was normalized before the relative peak intensity extraction. The functional group contribution to the spectra was taken as the normalized intensity at the selected wavenumber.

According to the infrared correlation table, the broad peak 3,400 cm -1 is assigned to the -OH vibration of the alcoholic or phenolic groups. The band between 2,940 cm -1 and 2,900 cm -1 represents the signature of the aliphatic -CH stretch of the methyl groups, which are related to single bonds involving prótons (STEVENSON, 1994). The wavenumber between 1,720 cm -1 and 1,660 cm -1 are associated with the C=O bonds of carboxylic groups (-COOH stretch), usually long chain and oxygen rich groups [START_REF] Bardy | Micromorphology and spectroscopic characteristics of organic matter in waterlogged podzols of the upper Amazon basin[END_REF]STEVENSON, 1994), that are present in fine humus in a weakly acidified environment (4.3<pH <5.5). The peaks in the spectral range of 1,590 cm -1 are due to the aromatic vibrations of C=CAr, which are more stable chains that indicate the presence of humic and fulvic acids in soil fractions (Stevenson, 1994); in podzols this band is associated with 3<pH <4.3 and organic matter that accumulates Fe 3+ [START_REF] Bardy | Micromorphology and spectroscopic characteristics of organic matter in waterlogged podzols of the upper Amazon basin[END_REF][START_REF] Olk | Decrease in Humification of Organic Matter with Intensified Lowland Rice Cropping: A Wet Chemical and Spectroscopic Investigation[END_REF][START_REF] Stevenson | Infrared spectra of humic acids and related substances[END_REF]. Peaks between 1,260 and 1,050 cm -1 result from C-O stretch vibrations (ether and/or alcohol).

Finally, the peak at 1,050 cm -1 indicates the presence of C-O in the polysaccharide forms [START_REF] Bardy | Micromorphology and spectroscopic characteristics of organic matter in waterlogged podzols of the upper Amazon basin[END_REF][START_REF] Olk | Decrease in Humification of Organic Matter with Intensified Lowland Rice Cropping: A Wet Chemical and Spectroscopic Investigation[END_REF][START_REF] Olk | Decrease in Humification of Organic Matter with Intensified Lowland Rice Cropping: A Wet Chemical and Spectroscopic Investigation[END_REF][START_REF] Olk | Decrease in Humification of Organic Matter with Intensified Lowland Rice Cropping: A Wet Chemical and Spectroscopic Investigation[END_REF]STEVENSON;[START_REF] Stevenson | Infrared spectra of humic acids and related substances[END_REF].

3.3.Results and discussion

Soils horizons characterization: morphology, texture; groundwater and pH

3.3.1.1.Morphology of soils

The morphology of the P1, P2 and P3 profiles is presented in Figure 2B. There are many morphological similarities between the P1 and P2 profiles. The primary differences between them are the horizon thicknesses, the presence of the AE horizon and the permanent groundwater at P2. In both the thick podzol and the hydromorphic podzol, the Munsell color is 5YR with color values ranging from dark gray to white for horizons A to E2. The color of EBh is black and Bh is dark reddish brown.

The organic matter corresponds to organic residues with recognizable structure in A11P1 and AP2. In horizons A11P1 and A12P1 and AP2 and AEP2, this organic matter forms pellets between the granules and sand grains or covers the grains. Organic matter films on the sand grains disappear and the pellets tend to disappear in the leaching horizons E1 and E2. Visually, in the horizons EBhP1 and BhP1, the organic matter is distributed homogeneously in the form of film coating the sand grains or occupying the porosity. The color value gradient and the organic matter distribution in the soil profiles reveal a system of accumulation-dissolution-accumulation of organic matter. Two sets of horizons were studied in the P3 profile: the solum and the granite alteration horizons. The color of the first horizon is 5YR, and the second horizon is 2.5Y. The color value varies from very dark gray to gray in the solum (A11P3 until A/EP3). The color of the BhsP3 horizons is black. Organic matter residues with recognizable pellet structures are predominately between the minerals in all the horizons, and they decrease in A/E P3 and tend to disappear in Bhs P3. In contrast, organic matter is dispersed throughout the Bhs horizon; it covers the sand grains and occupies the porosity, which suggests dissolution and mobility from the upper horizons and accumulation in this horizon. In comparison with the profiles P1 and P2, the P3 has a larger accumulation of organic matter, which suggests that water remains in the profile for a longer duration. The weathering horizons have a matrix 2.5Y and their color varies from light yellowish (Cg1P3) to white (Cg3P3) and without organic matter accumulation. 

3.3.1.2.Textural characterization of horizons

Texture distribution of soil profile horizons inside the texture triangle (Figure 3.3), as well as the data collected from granulometric analysis (Table 1), reveal that there is a very sandy pole (sandy and loamy sand) at the top and middle of the slope (P1 and P2) and a less sandy pole (sandy loam to sandy clay) at the lower slope (P3). In the Bh and Bhs horizons, the total sand ranges from 77.1 % (BhsP3) to 88.6 % (BhP2). For all the profiles, the coarse sand value is over 40.8 %, and the cryptopodzol has lower values. The silt content is very low in all horizons except for BhsP3, Cg1P3, Cg2P3 and Cg3P3 (Table 1). This amount of coarse sand can cause these layers to have high porosity. The sum of fine sand and silt varies from 17.6 to 32.5 % in profiles P1 and P2 (Table 1). The highest percentage of clay in both profiles is approximately 8.0 %, including the Bh horizons. The clay content increases from the surface to the base of the P1 and P2 profiles. In the cryptopodzol (P3), the fine sand and silt sum varies from 8.4 to 30.2 % (Table 1), except for the A12P3 and AEP3 horizons. Additionally, the clay content has a low value of 1.6 % for A12P3 and AEP2, and in the other horizons the clay content varies from 6.25 % (A11 P3 ) to 34.1 % (Cg3 P3 ). There is an increase in clay content from the surface to the base in P3. In comparison to the P1 and P2 profiles, the P3 profile is loamier (Figure 3.3, red points) based on the percentages of fine sand + silt + clay (Table 1). Due to their size and properties, the silt can be an impediment to the percolation of water through the horizons of the soils (CHANEY; [START_REF] Chaney | The influence of organic matter on aggregate stability in some Britisch soils[END_REF][START_REF] Harris | Dynamics of Soil Aggregation[END_REF][START_REF] Harris | Dynamics of Soil Aggregation[END_REF]ALLEN, 1966;HILLEL, 1980).The silt/coarse sand ratio (Silt/CoS) can provide an approximate measure of porosity (Table 1). For P1 and P2, the Silt/CoS is variable, which creates alternating permeable and less permeable horizons along the profile. For P3, from the surface to the base, Silt/CoS and thus soil waterproofing increases. There is a decrease in the soil porosity from the high and middle slope to the low slope.

3.3.1.3.Groundwater variation

The figure 3.2B shows the soil sequences with horizons and the groundwater top level in December 2013. At that time, the soils are emerging from the driest period. The waters are therefore beginning to rise. Consequently, the groundwater top varies between the profiles. For this reason, groundwater was only observed in P2 and P3. In the former, the groundwater top is 55 cm deep (top of the E2) and can oscillate to near surface (AE horizon) at the peak of the rainy season (November to July). In P3, the groundwater was assessed at 33 cm deep, but it can outcrop at the soil surface.

The figure 3.2A shows the groundwater level in June 2010 on profiles located in the soil sequences close and slightly parallel to the first one. During this period, the soils are exiting the wet season, and the water level begins to decrease. At that time, the groundwater top is approximately at 100 cm in E2P1 and at the top of horizon E2P2, approximately at 67 cm, which indicates that the groundwater retreat is faster in profile P1 compared to groundwater at December 2013, while P2 and P3 are always flooded.

Field prospecting showed that on December 2013, the horizons Bh, Bhs, and Cg1 of the P2 and P3 profiles were slightly humid and that the Cg3 horizon was completely dry. Thus, the groundwater begins to decrease in June from the top of the E1P1 and AEP2 horizons, disappearing completely at the peak of the dry season at P1 and remaining at the E2P2 base. Concurrently, in P3, the groundwater decreases from the top of A12P3 to the top of the A/EP3 horizon. In November, the groundwater begins to rise to the top of the E1 horizon in the P1 and P2 profiles, and it reaches the soil surface of P3 at the peak of the rainy season.

This groundwater dynamic reaffirms the difference between the three profiles: the horizons in P1 remain dry part of the year, while the groundwater is permanent in P2 and P3. Although the groundwater is permanent in P2 and P3, all the P3 horizons above Bhs remain wet during most of the year, which does not occur in P2.

3.3.1.4.Soils pH

Soil pH measurements refer to H + ions present in an aqueous soil extract. The soil samples pHH2O ranged from 5.18 to 3.02 (Table 3.1). For all the profiles, the measured pHH2O shows very high acidity and varies according to the horizon sets: the pH does not exceed 4.00 in the A11, A12 and A surface organic horizons or the Bh and Bhs spodic horizons in the P1 and P3 profiles. The pH is 4.23 in the hydromorphic podzol BhP2.

In the leached horizons AE, E1, E2 and EBh, the pHH2O ranges from 4.14 to 5.00 as well as in the Cg1P3, Cg2P3 and Cg3P3 weathering horizons (Table 3.1). This distribution shows a positive relationship between high acidity and the presence of organic matter in the organic surface horizons and in the spodic horizons.

3.3.2.Carbon content of soils and humic substances

3.3.2.1.Soils organic carbon distribution along the profiles and MO structures.

The organic carbon percentages (%C) in the soil are shown in Figure 4 (dotted lines). The carbon content in the profiles does not exceed 15 %, and the largest quantities are primarily in the surface organic horizons A11 and A for all three profiles. From the A11 and A horizons, the carbon content drastically decreases in all profiles, reaching 0.02 % in the E2 P2 , increasing again in the spodic horizons (Bh and Bhs) of P1, P2 and P3, and reaching a maximum of 12.4 % in Bhs. In the weathering horizons, the carbon percentage varies from 3.94 to 1.15 % and decreases from Cg1P3 to Cg3P3.

In the surface horizons A11, A12 and A, of the three profiles, the pellet structures are possibly associated with the production of primary carbon due, to rapid organic matter, which tends to decrease in the albic horizons with the solubilization of the organic carbon that is mobilized and later accumulated in the deeper horizons Bh and Bhs. In these accumulation structures, illuvial organic matter is found occupying the porosity and the surface of the grain surfaces. On the other hand, the accumulation of carbon corresponds to higher clay percentages in horizons the Bh and Bhs. In P3, the %C is globally greater than in the P1 and P2 profiles; however, the decrease in BhsP3 is accompanied by an increase in the clay quantities and a decrease in the porosity, which can prevent OM penetration. These horizons possibly function as a sieve assembly leading to the fractionation of the OM and allowing only the smallest molecules to pass through.

Thus the carbon distribution associated to the way MO is distributed through the three profiles (pellet, OM layers above the grains, OM filling the pores) reaffirms the existence of the accumulationdissolution-accumulation organic matter dynamic observed in the field. 

3.3.2.2.Organic carbon of extracted FA and HA.

The extracted HS carbon contents are presented in Figure 4. For the three profiles, unexpected values under 30 % carbon mass were determined for FA. The discrepancy between the carbon content of FA and HA is likely due to a non-organic contamination during the extraction process because the FA carbon content unexpectedly follows the same trend as the organic carbon in the horizons (Figure 3.4). Except for the P1 profile, no quantitative information was extracted from these data. However, a higher FA carbon content is observed for the A11P1 horizon (28.0 %C), decreasing until the E2P1 horizon (13.1 %C) and finally reaching 23.8 %C at the BhP1 horizon (Figure 3.4A).

On the contrary, the HA carbon content in P1 and P2 does not depend on the soil carbon content (Figures 3.4A and 3.4B). For HA, %C remains constant from A11P1 (41.4 %) to E1P1 (42.3 %), decreases to 26.1 % at E2P1, and finally increases again for EBhP1 (35.0 %) and BhP1 (40.9 %).

The same pattern was observed for the P2 profile, with higher values at BhP2 (45.0 %) and E1P2 (40.0 %) and lower values at E2P2 (25.0 %). In the P3 profile, the carbon content values are low ranging from 12.5 % for A11P3 to 0.2 % for A/EP3. Once again, these low values are likely due to mineral contamination, and only qualitative information should be used. However, the horizons below the BhsP3 horizon followed a trend of decreasing percentages up to the base of the profile (Cg1P3 3.9 %, Cg2P3 1.1 %, and Cg3P3 1.0 %).

These results are at the lower limit of the range variation expected for humic substances extracted from soil (LEGROS, 2012). The average %C found in humic substances from podzols, according to Legros, 2012, is 56 % for HA and 46 % for FA while [START_REF] Bravard | Podzols in Amazonia[END_REF], indicated that the %C of the humic substances in the podzols Amazonia soils range from 50 %C for HA and 43 %C for FA.

3.3.3.UV-visible spectroscopy: indices E2/E3 and E4/E6

The E2/E3 and E4/E6 ratios for FA and HA are presented in figure 5. In this figure, the relationship between the E2/E3 and E4/E6 ratios initially defines 2 data sets that clearly separate HA from FA. The first, to the right of the graph (group 3), represents HA for most of the samples in the three profiles except for the horizons A11P1 and AP2. The second set (groups 1, 2 and 4), to the left of the graph, represents primarily FA for most of the samples in the three profiles except for the Cg1P3, Cg2P3 and Cg3P3 samples. FA in all these horizons are as condensed as the FA in group 2. The texture, pH and carbon content do not have positive relationships with the aromaticity and condensation. The common characteristic of the group is the eventual presence or absence of water in the horizons.

The A11P1, A11P3 and AP2 horizons, have FA values with larger condensation variations in relation to E4/E6, and they are out of groups. The AP2 horizon is less condensed and less aromatic, while A11P3 is highly condensed and less aromatic. Thus, A11P1 contains FA with intermediate characteristics between AP2 and A11P3. They are sandy horizons with a pH value of approximately 3 and a medium to high total soil carbon content. Except for the temporary water saturation of A11P3, A11P1 and AP2 are dry for most of the year.

In general, FA has a high molecular weight structure with a range of aromaticity values (groups 1 and 2). The FA from horizon E seems to be located in the high aromaticity zone (E2/E3 <2).

All present a homogeneity concerning the molecular condensation from the E4/E6 index. This behavior in the analyzed soils may be due to larger chain structures being more resistant to the environment since most of these layers are eventually to frequently water saturated. The leaching mechanism could be responsible.

FA are more soluble than HA and so transported inside the soil profile when water reach their layer. The only FA moieties that remain in the solid phase are the highly condensed, i.e., more hydrophobic, moieties that are not transported by free water.This can explain why the remaining FA present a low E4/E6 index compared to HA. Canellas et al., 2001 found that FA tend to form intraand inter-molecular hydrogen bonds, and this behavior may be responsible for low E4/E6 ratio values by increasing the chemical bond condensation. The HA extracted from the studied soils show a large variation of E4/E6 index, i.e. condensation, and a fine band of aromaticity index. Only the superficial horizons such as AP2 escaped this tendency with a lower degree of condensation, because this pedoenvironment of surface receives fresh organic matter permanently. In these horizons, including A11 P1 and A11P3, this behavior is determined based on the low aromaticity.

In group 3, from right to left (Figure 3.5), the horizons of the 3 profiles form groups of HA that have condensation indexes (E2/E3) very close to each other. Except for the A/EP3 and E1P2

horizons, the horizons in the P1 profile have an E4/E6 index above 8 and those of P2 and P3 are between 5.8 and 8. The A11P1 and AEP2 horizons have an E4/E6 index of less than 5 and 4.5. Mostly independent on the texture, carbon content or pH, group 3 seems to depend on water table oscillation as well as the water presence, either permanent or not, along the 3 profiles horizons.Thus, the P1 profile has higher indexes and therefore has less condensed HA with medium aromaticity compared to P2. The podzolized horizons of P3 have indexes similar to P1, which are therefore situated in extremes with respect to the presence of water in the profile. For P2, the HA condensation is low, and the aromaticity is also low. The related horizons are under temporary to permanent water action (Figure 2). The horizons Cg1P3, Cg2P3 and Cg3P3 (group 4) have high condensation with aromaticity slightly similar to P1, and these horizons are may or may not be water saturated during the year.

However, these horizons have the highest clay content of the 3 profiles. The presence of clay possibly protects HA from humification through the formation of clay-organic complexes, which may explain the higher condensation and poor aromaticity. Stevenson (1994), states that humus can resist soil decomposition due to physical protection through clay-mineral interactions that form clay-metalorganic or clay-organic complexes; the latter is formed via hydrogen bonds.

In previous studies near Manaus [START_REF] Bravard | Characterization of fulvic and humic acids from an oxisol-spodosol toposequence of Amazonia, Brazil[END_REF], the E 4 /E 6 ratio was measured for surface and Bh horizons with HA values of 5.5 and 5.0 and FA values of 7.0 and 6.5, respectively. In [START_REF] Chen | Information Provided on Humic Substances by E4/E6 Ratios[END_REF], the measured E 4 /E 6 ratio for podzol extracted humic and fulvic acids was approximately 7.0 and 8.0, respectively. For extracted HA from Orthic Podzol in Germany, the value ranged from 5.1 to 10.2 similar to Mafra et al. (2007). This study determined FA values in the thick podzol of 4.0 to 2.0 for the A11 and Bh horizons, respectively, and 5.0 and 8.0 for humic acid. If the HA values are consistent with previous studies, we observed a discrepancy for the extracted FA. The E2/E3 ratio was used principally on aquatic organic matter studies. [START_REF] Peuravuori | Molecular size distribution and spectroscopic properties of aquatic humic substances[END_REF] found for HS in natural waters values between 3.9 to 4.3 for HA and 3.7 to 3.1. Guo and Jon Chorover (2003), measured the dissolved organic matter of EUA soils with higher values between 6.1 and 10.3.

Considering that these studies were performed for aquatic HS, the average HS value of the soils studied was approximately the same (0.75-11) without considering the differences between the fractions.

In general, terms, the UV-Vis results showed that, in this study, the extracted FA have a high condensation degree and higher aromaticity index and that HA have a lower condensation degree and a variable aromaticity index.

3.3.3.1.Distribution of condensation and aromaticity characteristics along the profiles

The clear difference between FA and HA for aromaticity and condensation, discussed in the previous item, readily visualized according to their distributions of the groups in the figure 5. On one hand it shows clearly the difference between the two fraction (FA and HA), but on another hand it is less clear to understand evolution of condensation and aromaticity along the profiles. For this, the figure 3.6, shows the trend variation along the profiles. For the FA the condensation and aromaticity tend in decreasing from thick podzol to cryptopodzol (considering only the podzolized horizons of P3). In the Cg layers the condensation is greater than aromaticity in all the profile. The tendency of HA is the increase of condensation and aromaticity from P1 to P2, and a decrease from P2 to P3

(considering only the podzolized horizons of P3), the horizons Cg1P3, Cg2P3 and Cg3P3 have the highest condensation and the lowest aromaticity of all the profiles. The main difference between the three profiles are the transition from thick podzol, of sandy texture, to cryptopodzol moderately clayey, and, at the same time the passage from pedoenvironments drier to constantly wet during the most part of the year, in the same direction, except for Cg1P3, Cg2P3 and Cg3P3.

For the FA the condensation and aromaticity seems to be dissociated from the texture in the profiles P1, P2 and in the podzolized horizons of P3. In the Cg layers the clayey texture and the drier environment are determinant for the increase condensation degree both FA to HA, because it protects the molecules to the humification (STEVENSON, 1994), also explaining why the lower aromaticity of FA and HA of the Cg1P3, Cg2P3 and Cg3P3. For the FA in the podzolization environment with more sandy texture the absence or eventual either temporary presence of water, has an important role to play for condensation and aromaticity degree. The HA, with the characteristics less condensed and more aromatic, it is separated from the texture in P1, P2 and in the podzolized horizons of P3, but it is associated to temporary presence of water related to the oscillation groundwater level. Thus, in the scale of the soil sequence, the condensation and aromaticity of the FA develops more intensely in the dry environments of the podzolization horizons. While for HA, in the scale of the soil sequence, condensation and aromaticity is more intense in a temporarily humid environment, the podzolization pedoenvironments (Figure 3.6). horizons. This indicates that the molecular size may be higher in E1P1 and E2P1 and slightly lower in EBh P1. The A11P1 and A12P1 horizons receive fresh organic matter from litter and has an average condensation and aromaticity degree, while BhP1 has slightly higher condensation and aromaticity compared to the last two (Figures 3.5 and 3.6); this indicates that the molecular size in E1P1 and E2P1.

A11P1 and A12P1 have medium to high porosity while Bh is more impermeable due to higher Silt/CoS (Table 3.1). The condensation and aromaticity of FA begins to rise in the zone of oscillating groundwater. In the dry and low porosity environment, the BhP1 aromaticity and condensation degree decrease. The horizons that receive a fresh OM supply tend to have lower condensation and aromaticity relative to the others.

Profile 2 is less porous overall (Table 3.1), and it is more humid than P1 most of the year because the water is temporarily in the above BhP2 horizons. Thus, the AEP2 and E2P2 horizons have more aromatic and condensed FA in the profile, while the BhP2 horizons are slightly more humid and less porous than in profile 1. Additionally, FA is slightly less condensed compared to E2P2 and less aromatic than the A P2 horizon. The surface horizon is an exception; it is more aromatic than condensed, and it is the drier profile. As observed in the P1 profile, there is a relationship between condensation and aromaticity with lower porosity (E1P2 and E2P2), indicating that the condensation depends on the groundwater fluctuation, and the aromaticity depends only on the porosity and dryness of the environment (Figure 3.7).

For groups 2 and 4 in figure 3.5, the horizons that belong to profile 3 are individualized relative to their behavior. This profile has less condensed and less aromatic HS, and it is more humid and less porous when compared to the other profiles, except for the BhsP3, Cg1P3, Cg2P3 and Cg3P3 horizons. Additionally, the Clay/Silt content in P3 is high in the BhsP3 and CgP3 layers, and the lower porosity is confirmed by the high Silt/CoS ratio (Table 1). The Silt/CoS ratio shows that the porosity in BhsP3 and Cg2P3 is similar while for Cg3P3 it decreases drastically, making these horizons dry most of the time or permanently dry in the case of Cg3P3 (Figure 3.7). This porosity decrease is also observed from A/E P3 to Bhs P3 , but these horizons are water flooded all the time. Between the surface horizons and A/EP3, the porosity increases constantly (Figure 3.7). Hence, it is believed that both the Cg1 P3 and Cg3 P3 horizons and to a lesser extent the Bhs P3 horizon, constitute texture obstacles. The A11P3 surface horizon has lower aromaticity and higher condensation, possibly due to the contribution of fresh MO. In A12P3, the behavior is the opposite; the condensation is lower and the aromaticity is higher due to the lower porosity. In the zone of groundwater oscillation for A/EP3, the porosity is smaller which causes the high aromatization and condensation of the FA via solubility selection. In the BhsP3, although the horizon is less porous, it retains moisture because it is above Cg1P3 (12 % silt and 11.45 % clay), which leads to less aromatization and condensation of FA. This distribution of FA aromaticity and condensation depicted in figure 7 indicates that the lower porosity in the groundwater oscillation zone positively influences the higher condensation and aromaticity of the FA in the P3 profile. However, it is a secondary role in the aromatization and condensation of FA in high humid environments. In dry environments, their role is important, leading to a high aromatic degree for FA.

The HA distribution along the profiles is different compared to FA (Figure 3.6). Due to the high aromaticity, the HA in all the horizons of the P1 profile has a homogeneous distribution, but there are few differences according to the porosity in the profile. In the horizons with higher porosity (A12P1 and EBhP1), the aromaticity is slightly lower than in the other horizons, and both horizons remain dry or eventually have water (Figure 3.7). Although the aromaticity in P2 is generally higher, the aromaticity distribution of HA is similar to P1. In all the horizons of the three profiles, except in the Cg1P3, Cg2P3 and Cg3P3 horizons, HA is more aromatic and less aromatic in the low porosity horizons independent of water saturation, indicating that low porosity retains larger aromatic particles, while the smaller particles that are slightly less aromatic can migrate through the smaller pores and are distributed to the subsequence horizons according to size.

In the horizons with the Cg layer, the aromaticity is approximately the same. The small increase in humidity for Cg2P3 due to the textural obstacle in Cg3P3 does not significantly influence the aromaticity variation. The Cg1P3 and Cg3P3 horizons are drier and have lower porosity compared to Cg2P3, and the aromaticity decreases relative to horizons above BhsP3. This indicates that the molecules that can pass through the BhP3 are very small HA molecules, which were fractionated by porosity.

The condensation degree of HA is lower in all the profiles and appears to not only depend on porosity. In P1, P2 and the podzolization horizons of P3, one can note that the high condensation in HA depends more on the humid pedoenvironment and is independent of the porosity, although in the profiles there are small porosity variations: in the P1 and P2 profiles, HA is more condensed in the environment with less porosity, both in the dry pedoenvironment (A11p1) and intermittent water such as E2P1, BhP2 and A11P3. More condensation occurs in environments with higher porosity and intermittent water (AEp2) or permanent water E2P2 (Figure 3.7). Except for the horizons A11P1 and A11P3 and BhP2, the other horizons have groundwater oscillation levels that may explain the high condensation degree. Due to the upper leaching in this zone, the particles that are less condensed and smaller can be mobilized when the groundwater declines and accumulates in the subsequent horizons that have lower porosity.

Concurrently with the aromaticity decreases in the Cg horizon layers, the HA condensation degree in the same layers increased significantly in Cg1P3, and they sharply decreased in Cg2P3 and Cg3 P3 accompanying the reduction of humidity and porosity. In this way, HA particles are mobilized from BhP3 that are more condensed and larger than those accumulating in Cg1P3; the smaller particles are fractionated between Cg2P3 and Cg3P3. The values of the condensation indexes are very close in the last two horizons and have greater resistance to humification.

Infrared Spectroscopy in humic substances

The analyzed spectra acquired for the HS were typical of those found for soil organic matter The highest normalized absorbance for HA corresponds to the polysaccharide group (1,050 cm -1 ) in all horizons of all the profiles, except for the E2P1 horizon. Figure 3.9 shows the inverse distribution of the polysaccharide function intensities in the two humic fractions, and that this functional group is present in all horizons of the three soils. [START_REF] Hergert | The Infrared Spectra of Lignin and Related Compounds. I. Characteristic Carbonyl and Hydroxyl Frequencies of Some Flavanones, Flavones, Chalcones and Acetophenonesl[END_REF] and [START_REF] Zech | Factors controlling humification and mineralization of soil organic matter in the tropics[END_REF] showed a loss of polysaccharides and phenolic components during the humification process, and the modification of lignin structures with an enrichment in recalcitrant non-ligninic aromatic structures. However, the lignin FTIR spectra do have high contributions to the (C=CAr) and

(ether/alcohol) bands (HERGERT; [START_REF] Hergert | The Infrared Spectra of Lignin and Related Compounds. I. Characteristic Carbonyl and Hydroxyl Frequencies of Some Flavanones, Flavones, Chalcones and Acetophenonesl[END_REF][START_REF] Zech | Factors controlling humification and mineralization of soil organic matter in the tropics[END_REF]. Although the intensity of the 1250 cm -1 band is as high as that of the polysaccharide group, the band at 1,590 cm -1 is relatively lower for HA, whereas the FA bands at 1,050 cm -1 and 1,250 cm -1 are lower and the band at 1,590 cm 1 (C=CAr) is higher. This inverse configuration between FA and HA confirms the different behaviors of the two humic fractions and shows the transformative dynamic, in accordance with the apparent weak condensation measured for HA using the UV-Vis index, whereas for FA this configuration reveals the consistency with the condensation measured using the UV-Vis index.

The 1,250 cm -1 (stretch C-O, ether/alcohol) HA wavenumber has the second highest value of all the profile patterns. In profile 2, this band has the lowest intensity (ABS<0.1) in all horizons. For FA, normalized absorbance are lower than for HA in this functional group. Among all the profiles, the highest value (ABS=0.19) of this function for FA is in the horizon A P2 , while the lowest intensity is approximately ABS=0.05 and occurs in the E1P1, E1P2 and Cg3P3 horizons. For groundwater presence in the profiles, the hydromorphic podzol remains drier than P3, indicating that the constant presence of water in the profiles does not interfere with the distribution of the functional group ether/alcohol. However, considering that FA and HA have different behaviors, P2 has the lowest intensities for both FA and HA, except for FA in the AP2 horizon. Concurrently, P1 and P2

have the lowest Silt/Cos of the three profiles, except for the horizons E2P1, BhP1, AP2 and BhP2. The Silt/CoS ratio is also low in A/EP3. However, the dynamic of groundwater variation in the dry and humid period showed that the horizons up to BhP1 in profile 1 remain wetter during the year.

According to these singularities, the distribution of the ether/alcohol function in the profiles is directly related to the water level variation in the periods of elevation and lowering of the water table level, juxtaposed to the efficiency of water percolation (Silt/CoS) in all three profiles. As a consequence, HS containing such a functional group can be solubilized and mobilized from the most porous and permeable horizons in the groundwater zone and are immobilized in the less porous horizons, slightly richer in fine matter, silt and clay, which are supplying metals to be complexed. In fact, ether/alcohols, esters, diketones and aldehydes are recognized to be very soluble, have high mobility and are able to form organometallic complexes with Fe(II) or Al(III) (HOLM; O'CONNOR, 1λ71).

The third highest absorbance is represented by wavenumber 1,590 cm -1 (C=CAr) in all the profile horizons with the HA extract. The horizons BhP1 (ABS = 0.27) and BhP2 (ABS = 0.26) have a higher intensity and it is possibly associated with the organic matter resulting from the illuvial accumulation as shown by the thin layer of organic matter coating the quartz grains and occupying the porosity.

The A/EP3 horizon has a lower intensity (ABS = 0.1), the most leached horizon of the profile, and Cg1 P3 and Cg2 P3 are less permeable. Conversely, the absorbance values of (C=C Ar ) for FA are higher compared to HA. The highest absorbance (ABS = 0.31) occurs in the A12P1 horizon, where organic matter forms pellets. The lower intensity is in BhP2. These data and the analysis of the histograms (Fig. 9) compared to the textural data and the groundwater dynamics indicate that the larger intensities of this functional group are not necessarily associated with the horizons that have higher silt + clay content and to the permanence or not of the water in the horizons. The greatest sand content, and especially the coarse sand and the lower Silt/CoS ratio (Table 3.1), is associated with high porosity in the soil horizons. It is observed that there is a positive relationship between the porosity and the values of the intensities obtained for the aromatic functional group, both FA and HA, except for FA in profile 2. Comparing this tendency with the E 2 /E 3 ratio results (Figure 3.5), the more porous horizons retain the larger particles of both FA and HA. Thus, it is possible to suggest that HS containing aromatic groups can be distributed in the profiles according to the higher or lower porosity of the horizons, promoting fractionation of the two HS fractions, which is in agreement with results obtained by [START_REF] Bardy | Micromorphology and spectroscopic characteristics of organic matter in waterlogged podzols of the upper Amazon basin[END_REF]. In this study of Amazonian Podzols [START_REF] Bardy | Micromorphology and spectroscopic characteristics of organic matter in waterlogged podzols of the upper Amazon basin[END_REF], determined that this function may be in OM as coarse granules (polymorphic-pellets) filling the pores, or it may be in the Bh horizon as a result of either in situ humification in this horizon or by illuvial accumulation since low molecular weight OM can migrate and accumulate in less porous horizons, such as Bh.

The peak intensity represented by the carboxylic group (C=O) (1720 cm -1 -1660 cm -1 ) has an absorbance of 0.26 in BhP1, followed by 0.25 in BhP2. P1 and P2 profiles have greater intensities whereas the P3 absorbance is lower. In the latter, the highest absorbance is 0. approximately the same as the aromatic group, and seems to have a positive relationship with porosity. However, such a relationship is not very clear since OM, rich in carboxylic function, may be more soluble than the aliphatic and aromatic groups. Additionally, it is likely mobilized more easily to lower horizons in the profiles, in which the hydrogen of the OH group can be substituted by a metal ion available in the fine matter to form carboxylate. The latter can accumulate in the horizons due to chelation forming complexes with aluminum [START_REF] Bardy | Micromorphology and spectroscopic characteristics of organic matter in waterlogged podzols of the upper Amazon basin[END_REF] due to the great affinity of this functional group with this cation (Elkins and Nelson, 2002).

The intensities of aliphatic group (2,940 cm -1 -2,900 cm -1 ) are low for both HA and FA. For HA, the highest absorbance of the aliphatic group is approximately 0.05 in the horizons A11P1, A12P1, EBhP1, AP2, AEP2, E1P2, A12P2, A/EP3, Cg1P3, and Cg2P3, while the smallest (ABS = 0.01) is in A2P3 and Cg3P3. For FA, the greater intensities are in P1 with ABS = 0.11 for E2P1, while the smaller are in E1P2, Cg1P3, Cg2P3 and Cg3P3. According to [START_REF] Bardy | Micromorphology and spectroscopic characteristics of organic matter in waterlogged podzols of the upper Amazon basin[END_REF] in the studies of Amazonian Podzols, the OM has a polymorphic structure, containing residues and dominantly OM with aliphatic functions juxtaposed to the quartz grains. Bardy´s study indicates that this OM with aliphatic functions derives from accumulated residues and poorly palatable roots and leaf constituents.

Moreover, the aliphatic functional group seems independent of the presence of water. [START_REF] Bravard | Characterization of fulvic and humic acids from an oxisol-spodosol toposequence of Amazonia, Brazil[END_REF], argue that the low clay content of podzol profiles increases the ability of compounds with low molecular weight to be removed from the surface horizons. Additionally, large molecules and plant debris can be retained in the surface horizon of the podocytes. Thus, it is proposed that the organic matter with aliphatic functions can migrate more easily in the studied profiles due to the higher porosity of the coarse sand. Migration stops at the clay horizons where they remain, which leads to an increase of the aliphatic FTIR band contribution.

The configuration of the normalized intensity distribution of the functional groups, shown in figure 9, revealed few differences in the distribution of the functional groups for either HA or for FA.

However, the profile 2, for both SH, is the most different, possibly related to the low amount of C extracted for FA, which may affect the FTIR response. Comparing the figures 3.9 and 7, it can be seen that the lower E2/E3 index does not necessarily correspond to the higher intensity, for example,

for the band at 1,590 cm -1, in the same way, as higher condensation (E4/E6 low) does not correspond to the lowest intensity of the band 3,440-3,100 cm 1.

The analysis performed by profile, was able to interpret that the little difference in the intensities distribution of the functional groups for HA and FA, expressed in figure 3.9.Which could possibly arises from the fact that the intensities for each functional group refers to the quantity, and less to the singularity expressed due to the higher solubility of FA in comparison to HA. That is, the differences in the horizons distribution of functional groups possibly follows the greater or less solubility of SH, together with the characteristics of the functional groups compared to the pedoenviroments of soils horizons.

3.3.5.Statistical considerations

The figure 3.10 present the results from the Principal Component Analysis (PCA) to the profile soil horizons, according to the distribution of HA and FA with the FTIR normalized intensity, UV-Vis ratio and Silt/CoS ratio. The most representative PCA axes CP1 and CP2 explained the variance of 54.4% as shown in the figure 3.10A.

of the right south (S) quadrant, while Cg3 P3 -HA is in the left quadrant S, not too far from groups A and B.

Group A contains FA and HA. Most samples are HA, and these samples are located around the center of the two-dimensional projection extending from the left quadrant South (S) and the left quadrant North to the West direction (W). The horizons with FA are diffuse inside group A. Group B has only HA and is located in the S of the left quadrant near group A and extends to the left quadrant.

Group C is situated at the North left quadrant and contains only FA. The groups D and E are the furthest from the central axis and extend in the eastern direction of the quadrant. Similarities seem to exist between some horizons that occupy the same group and between some AF-horizons with HA horizons that cluster in group A.

The figure 3.10B reflects the original variable influences of the main components on the group's delimitation. The greatest influence on groups A, B and C, for both HA and FA, is exerted by the functional groups and by the condensation (E4/E6) and aromaticity (E2/E3) indication.

The HA of group A can be divided in three subgroups with the following behavior: one upper subgroup (N left) gathering A11P1, AP2, E1P2, and A/EP3, which is directly related to an intensity of functional groups (-CH) and (-OH) and negatively correlated to the variables from left quadrant S. with the porosity (Silt/Cos), and less strongly with the variables of the left quadrant S. In fact, this horizon presents high porosity and the FA is condensed and aromatic.

For FA the absorbance of (-OH) and (-CH) have a positive relationship with the horizons present in group C (E2P1; A12P3). The BhP1 and A11P3 horizons, although present in group A, are close to group C. All the samples have a high condensation degree (lower E4/E6) and intensity moderate intensity of (-OH) and (-CH aliphatic) thus constituting an apparent contradiction.

The groups D and E, and the horizons distributed sparingly in the right quadrant N and S all representing FA, have aromaticity (E2/E3) and porosity as the major influence on them. In fact, the horizons of group D and the ones in E1P1, AP3, Cg3 P3 closer to the vectors E2/E3 and Silt/Cos, are very aromatic, but have small or large porosity, this fact proves for E1P1 and AP3, and for the horizons of the group D that porosity plays a secondary role in flavoring in occasional or temporarily watersoaked environments, and for Cg3P3, which is very close to the two vectors, that poorly porous pedoenviroments lead to an increased aromatization in dry environments as seen by UV-Vis results.

The horizons of group E, and the horizon Cg2P3, further away from the two vectors E2/E3 and Silt/Cos and the vectors for the variables of the left quadrant N and S, are in possibly humid pedoenviroments, are little aromatic and have both large and small porosity, being influenced by the variables considered in the PCA.

The analysis on the main components highlighted the importance of functional group intensities on the delineation of the groups described above, as well as emphasized the direct relationship between the E 4 /E 6 index and the left quadrant functional groups. The horizon distributions in two dimensions indicate that FA and HA are different and it emphasizes the UV-Vis results. In fact, the HA are agglomerate within the groups, and the horizons are close to each other due to the large similarity between the HA fractions. This behavior does not occur for FA, which are widespread, showing FA fraction variability.

The horizon distributions in two dimensions indicate that FA and HA are different and it emphasizes the UV-Vis results. In fact, the HA are agglomerate within the groups, and os horizontes are close to each other due to the large similarity between as frações de HA. This behavior does not occur for FA which are widespread, showing the FA fractions variability. By UV-Vis analyzes FA is more condensed and aromatic than HA. The ACP, however, points out that the FA of most horizons (10 horizons) is aliphatic and hydrophilic in character and it has a negative correlation with the E4/E6 and E2/E3 indices. Six (6) horizons have FA that shows a positive correlation with the E4/E6 and E2/E3 indexes and with the porosity, as they present predominantly aromatic and carboxylic character and secondarily character determined by etheralcohol and polysaccharide functions. From this, and in addition to the interpretations obtained with UV-Vis and FTIR, it is possible to evaluate that regarding distribution of the most aromatic and carboxylic FA in the horizons of the soil profiles, the greater porosity is fundamental in order that these FA fractions migrate and are immobilized to subsequent horizons, less porous, and with availability of metals such as Al.

The PCA shows that HA is primarily determined by the polysaccharide, ether-alcohol and aromatic functions (11 horizons), and secondarily by the aliphatic and OH functions (5 horizons), as well as the 11 horizons have a positive correlation with E4/E6, indexes such as E2/E3 and with porosity.

Due to that, along with interpretations obtained from the UV-Vis and FTIR data, the porosity and sheet flotation in the horizons is determinant for the distribution of the HAs containing polysaccharide, ether-alcohol and aromatic functions. Possibly the sheet level fluctuation as well as the availability of metals, such as Fe, in the horizons, is determinant, and more important, for HA distribution with predominance of ether and alcohol functions.

Conclusions

The methods used proved to be efficient in reaching work objectives as well as the statistical treatment allowed to refine interpretations. In this way, it was possible to characterize the two humic fractions, and to show the difference in behavior between the both, also to identify soil characteristics that determine distribution rules of the FA and HA, either in the soil sequence on the slope or in the horizons of the soil profiles.

For both HA and FA the average % C for the humic substances is lower than the limit of the expected soil. The FA is more condensed and aromatic than HA. The first one has 10 horizons containing FA with hydrophilic and aliphatic character, and 6 horizons with character defined by the aromatic and carboxylic functions. The second one has 11 horizons with character defined by the polysaccharide, and ether-alcohol functions and 5 horizons with aliphatic and hydrophilic character. These characteristics reveal a strong difference between FA and HA, and define, along with the characteristics of the pedo-environments, the behavioral difference of both HS. Soil morphology, texture, porosity (Silt/Cos), the presence or not of water in the horizons of soil profiles, and the fluctuation of the soil bed in the soil are the main characteristics of the soils that interfere in the behavior of the two humic fractions throughout the year.

Such pedological characteristics also define the FA and HA distribution rules in the sequence of soils on the slope, and in the horizons of soil profiles. The morphology, texture, and the presence or absence of water in these profiles react to the distribution of both humic slope fractions, while the porosity and the flotation of the sheet in the horizons interfere in the distribution of FA and HA in the horizons of the soil profiles.

In order to the FA the condensation and aromaticity to decrease from thick Podzol to the cryptopodzol of the slope base, following the increase of water presence in the profiles during the year, without considering Cg horizons that have high condensation and aromaticity, due to the lower humidity of the horizons due to low porosity. The aromaticity and condensation of AH increases from Thick Podzol to Hydromorphic Podzol, and then decreases to Crytopodzol. This configuration depends on the temporary presence of water in the Hydromorphic Podzol. Cg horizons that have high condensation and low aromaticity, coupled with the greater presence of clay that inhibits the humification of HA are excluded to this rule.

In the profiles the distribution rules of FA are: 1) Low porosity leads to greater condensation in the leaf beating zone, or in dry environment possibly saturated by water, 2) while low porous and dry pedoenviroments lead to a decrease in condensation, so this process depends on the increase of sheet flotation; 3) Low porosity in the horizons of the sheet oscillation zone positively influences the aromaticity in the pedoenvironments, often humid or dry with eventual visit of the water; 4) Porosity plays a secondary role in flavoring and condensation in very water-soaked environments.

As for the HA, the horizon aromaticity of the soil profiles is related to the most porous envoriments and it is independent of the sheet water oscillation. However in the temporarily more humid environments, the aromaticity of the HA is higher, and in the dry and clayey environments it is lower. The higher HA condensation is independent of the porosity, regarding oscillation sheet zone; but it depends on greater porosity in horizons with permanent water. determinou-se a presença de dois componentes presentes para cada amostra de ácido fúlvico e ácido húmico. A K variou de logK = 3.66 a 5.00 e a CC variou de 3, 83.10 -10 mol.mgC -1 a 1, 06.10 -06 mol.

mgC -1 . A comparação dos resultados demonstrou diferença da força de ligação para os metais e diferença da capacidade de complexação para AF e AH e que alguns grupos funcionais podem ser envolvidos nas propriedades de complexação das SH dos solos podzolizados.

Palavras-chave: ácido húmico, ácido fúlvico, podzóis, fluorescência quenching, Amazônia.

Introdução

Os solos podzolizados estão presentes em aproximadamente 485 milhões de hectares no mundo e foram descritos tanto em regiões boreais ou frias do globo (LUNDSTRÖM; [START_REF] Lundström | The podzolization process. A review[END_REF][START_REF] Lundström | The podzolization process. A review[END_REF] como em regiões tropicais (BRAVARD; [START_REF] Bravard | Podzols in Amazonia[END_REF]CHAUVEL;LUCAS;BOULET, 1987b;[START_REF] Do | Podzolization as a deferralitization process: A study of an Acrisol-Podzol sequence derived from Palaeozoic sandstones in the northern upper Amazon Basin[END_REF][START_REF] Dubroeucq | From Oxisols to Spodosols and Histosols: evolution of the soil mantles in the Rio Negro basin (Amazonia)[END_REF][START_REF] Dubroeucq | From Oxisols to Spodosols and Histosols: evolution of the soil mantles in the Rio Negro basin (Amazonia)[END_REF][START_REF] Lucas | Systemes sols ferrallitiques -podzols en region amazonienne[END_REF].Com morfologia singular tais solos refletem a ação dos processos da podzolização no qual as substâncias húmicas (SH) dissolvidas e ácidas são agentes principais do intemperismo mineral; da complexação e mobilização de complexos organo-metálicos, predominantemente com Fe e Al, e da precipitação de matéria inorgânica pouco cristalina (fases de Fe, Al e Si) (LUNDSTRÖM; [START_REF] Lundström | The podzolization process. A review[END_REF][START_REF] Lundström | The podzolization process. A review[END_REF].

As SH contém uma variedade de grupos funcionais orgânicos tais como: carboxílicos (COOH), fenólicos (OH), thiols (SH), aminas (NH2), entre outros. A presença destes grupos funcionais garante as SH as propriedades de interagir com íons metálicos (COBLE, 2007;[START_REF] Guo | Characterizing the fluorescent properties and copper complexation of dissolved organic matter in saline-alkali soils using fluorescence excitation-emission matrix and parallel factor analysis[END_REF][START_REF] Senesi | Molecular and quantitative aspects of the chemistry of fulvic acid and its interactions with metal ions and organic chemicals. Part I. The electron spin resonance approach[END_REF] excitadas por uma radiação eletromagnética em um determinado comprimento de onda, e ao retornarem ao estado fundamental ocorre a emissão de um fóton (Lakowicz, 1999). Estas diferenças vibracionais entre excitação e emissão fornece informações sobre as SH.

A fluorescência pode ser obtida utilizando o modelo que envolve a coleta de múltiplos espectros de emissão em uma gama de excitação que estão ligados a uma matriz (COBLE, 2007;[START_REF] Senesi | Molecular and quantitative aspects of the chemistry of fulvic acid and its interactions with metal ions and organic chemicals. Part I. The electron spin resonance approach[END_REF]; este tipo de fluorescência é conhecido como fluorescência de emissão e excitação (EEM).

A fluorescência EEM é uma ferramenta que favorece a identificação dos aspectos qualitativos no nível molecular e quanto às interações das SH com íons metálicos [START_REF] Bayer | Tillage and cropping system effects on soil humic acid characteristics as determined by electron spin resonance and fluorescence spectroscopies[END_REF], esta última baseada nas análises de fluorescência quenching [START_REF] Mounier | Copper complexing properties of dissolved organic matter: PARAFAC treatment of fluorescence quenching[END_REF][START_REF] Smith | Metal speciation in natural waters with emphasis on reduced sulfur groups as strong metal binding sites[END_REF][START_REF] Smith | Metal speciation in natural waters with emphasis on reduced sulfur groups as strong metal binding sites[END_REF][START_REF] Smith | Metal speciation in natural waters with emphasis on reduced sulfur groups as strong metal binding sites[END_REF].

Normalmente, a fluorescência quenthing é aplicada para definir as constantes de estabilidade condicional (K) e a capacidade de ligação utilizando o modelo matemático de Ryan e Weber. O modelo assume uma relação linear entre a concentração de metal complexado com a MO e a mudança na intensidade de fluorescência (CABANISS; [START_REF] Cabaniss | Comments on "fluorescence quenching measurements of copper-fulvic acid binding[END_REF]. Dessa maneira, permite o cálculo dos parâmetros para um sítio padrão, individual no modelo de fluorescência quenching (CABANISS; [START_REF] Cabaniss | Comments on "fluorescence quenching measurements of copper-fulvic acid binding[END_REF]ESTEVES DA SILVA;[START_REF] Da | Multivariate curve resolution of multidimensional excitation-emission quenching matrices of a Laurentian soil fulvic acid[END_REF][START_REF] Da | Multivariate curve resolution of multidimensional excitation-emission quenching matrices of a Laurentian soil fulvic acid[END_REF]. Sítios de ligação causadores da fluorescência quenthing ou sítios de ligação fluorescentes são creditados como formadores de complexos 1:1 entre a matéria orgânica e os cátions metálicos, como por exemplo do tipo Cu +2 (GUO et al., 2015).

Porém, após a aplicação da fluorescência EEM uma grande quantidade de resultados é obtida o que dificulta a identificação dos picos e as quantificações podem ser imprecisas e subjetivas (COBLE, 2007), técnicas de análise multivariadas são aplicadas, como a CP/PARAFAC são aplicadas para melhorar a informação.

O uso da modelagem CP/PARAFAC permite a decomposição dos componentes fluorescentes da fluorescência EEM, que representam grupos funcionais que fluorescem na MO (LUCIANI et al., 2008;[START_REF] Mounier | Copper complexing properties of dissolved organic matter: PARAFAC treatment of fluorescence quenching[END_REF].Portanto a combinação EEM CP/PARAFAC pode ser utilizada para a caracterização quantitativa da matéria orgânica fluorescente (MOF) o que facilita a identificação e quantificação de sinais subjacentes, denominados componentes [START_REF] Murphy | Measurement of dissolved organic matter fluorescence in aquatic environments: An interlaboratory comparison[END_REF], e também pode oferecer resultados quantitativos para caracterizar as propriedades de ligação da MO com os íons metálicos [START_REF] Guo | Characterizing the fluorescent properties and copper complexation of dissolved organic matter in saline-alkali soils using fluorescence excitation-emission matrix and parallel factor analysis[END_REF][START_REF] Mounier | Copper complexing properties of dissolved organic matter: PARAFAC treatment of fluorescence quenching[END_REF][START_REF] Plaza | Copper(II) complexation of humic acids from the first generation of EUROSOILS by total luminescence spectroscopy[END_REF][START_REF] Plaza | Copper(II) complexation of humic acids from the first generation of EUROSOILS by total luminescence spectroscopy[END_REF][START_REF] Plaza | Copper(II) complexation of humic acids from the first generation of EUROSOILS by total luminescence spectroscopy[END_REF].

Estudos vêm utilizando a técnica de fluorescência EEM tanto para a caracterização das componentes fluorescentes das SH (ácidos fúlvicos e húmicos) (HUNT; [START_REF] Hunt | Characterization of fresh and decomposed dissolved organic matter using excitation-emission matrix fluorescence spectroscopy and multiway analysis[END_REF][START_REF] Sierra | Fluorescence fingerprint of fulvic and humic acids from varied origins as viewed by single-scan and excitation/emission matrix techniquesChemosphere[END_REF], como voltados para a associação com metais através da determinação das constantes de complexação baseados em Ryan e Weber (1982) (ELKINS; [START_REF] Elkins | Fluorescence and FT-IR spectroscopic studies of Suwannee river fulvic acid complexation with aluminum, terbium and calcium[END_REF][START_REF] Lu | Characterization of copper complexation with natural dissolved organic matter ( DOM )-link to acidic moieties of DOM and competition by Ca and Mg[END_REF][START_REF] Lu | Characterization of copper complexation with natural dissolved organic matter ( DOM )-link to acidic moieties of DOM and competition by Ca and Mg[END_REF][START_REF] Merdy | A new method using laser induced fluorescence quenching for studying metal complexes in the solid state applied to CrIII, CuII and PbII in sandy soils[END_REF][START_REF] Mounier | Copper complexing properties of dissolved organic matter: PARAFAC treatment of fluorescence quenching[END_REF][START_REF] Smith | Metal speciation in natural waters with emphasis on reduced sulfur groups as strong metal binding sites[END_REF][START_REF] Smith | Metal speciation in natural waters with emphasis on reduced sulfur groups as strong metal binding sites[END_REF][START_REF] Smith | Metal speciation in natural waters with emphasis on reduced sulfur groups as strong metal binding sites[END_REF]. [START_REF] Elkins | Fluorescence and FT-IR spectroscopic studies of Suwannee river fulvic acid complexation with aluminum, terbium and calcium[END_REF] Ao final do processo de extração 36 amostras de SH foram obtidas (18 de AF e 18 de AH). [START_REF] Mounier | Differentiation of organic matter's properties of the Rio Negro basin by crossflow ultra-filtration and UV-spectrofluorescence[END_REF]. Ao final do teste, a faixa de diluição de 10 mg.L -1 foi determinada por corresponder à zona de linearidade da resposta de fluorescência que foi utilizada no estudo.

O estudo da capacidade de complexação dos AF e AH com os íons metálicos de Cu 2+ e Al 3+

foi realizado utilizando um esquema de diferentes concentrações (0 até 105,9 mg.L -1 ) em 16 cubetas de quartzo de 1 cm (Tabela 4.1 e Figura 4.1); os extratos de AF e AH foram dissolvidos na concentração de 10,0 mg/L com uma solução tampão de acetato de sódio (0,001 mol.L -1 ), o pH variou entre 5,0 e 6,0 depois das adições dos metais. As soluções de metais utilizadas foram CuSO4.5H2O (0,01 mol.L -1 ) e Al2(SO3).18H2O (0,01 mol.L -1 ). A análise estatística das EEM CP/PARAFAC foi realizada por meio do Software MATLAB R2013a, através da extensão "progmeef", desenvolvida por R. Redon do laboratório PROTEE. O algoritmo do software é baseado no trabalho de Bro (1997). O número de componentes foi escolhido usando a Análise da Consistência do tenso Núcleo -CORCONDIA -(do inglês, CORe, CONsistency, DIAgnostic-). A CORCONDIA consiste na estimativa da qualidade do modelo em capturar informações trilineares; caso a consistência seja baixa (<60%) a utilização do modelo é inválida. (Bro, Kiers,2003). Segundo Bro (1997) o número de componentes que melhor se ajustam ao modelo deverá resultar em CORCONDIA superior a 60%. 

Determinação da Constante de Estabilidade Condicional e Capacidade de Complexação

= [ML1] / [L1] [M] e K2 = [ML2] / [L2] [M] (6) CL1 = [ML1]+[L1] e CL2 = [ML2]+[L2] (7) M0 = [ML1] + [ML2] + [M] (8)
Onde CL1 e CL2 são os números totais de sítios disponíveis para complexação da amostra. Onde IFi e M0i são as contribuições do componente e a concentração total de metal adicionado "i" no experimento de quenching. O ajuste de cada experimento de quenthing foi realizado utilizando um algoritmo de simplex com constrintas positivas pelos parâmetros, com a função modificada "fminsearch" de Matlab. Os dois modelos foram escolhidos porque são simples e rápidos para investigar as propriedades de complexação da matéria orgânica. Para isso, foi comparado os BIAS dos dois modelos para todos os experimentos de quenthing dos AH e AF, para as componentes C1 e C2.

4.2.3.2.Determinação do modelo de análise

Para cada um dos modelos de complexação citados foi determinado os parâmetros de A figura 4.4 apresenta a distribuição das 7 componentes nos perfis de solos e nos horizontes. 2008). Neste estudo a determinação da CC foi realizada com relação a massa de carbono obtida para as substâncias húmicas:

CC i = (CL 1 , C1 + CL 1,C2 ) / (mHS i * %C i )
Onde CCi é a capacidade de complexação da amostra "i" em mol of M per mg of C (M = Cu ou Al), CL1, C1 e CL1,C2 os números de sítios de complexação da amostra calculado respectivamente pela componente CP/PARAFAC, C1 e C2; mHS é a massa de substância húmica (AF ou AH) na amostra (10 mg.L -1 neste trabalho) e %Ci a percentagem de carbono em massa na substância húmica analisada.

Os valores obtidos para a constante tanto para o Cu +2 como para o Al +3 podem ser observados na figura 4.7. Os AH possuem maior peso molecular, por isso a maior disponibilidade de sítios para complexação. Significando que a quantidade de metais usada no experimento não foi suficiente para saturar todos os sítios para complexação. Nos AF o comportamento não é o mesmo uma vez que estes possuem um peso molecular menor, significando que a quantidade doe metais usada no experimento foi suficiente para saturar os sítios disponíveis para complexação. As análises permitiram indentificar diferentes participações dos AF e AH com relação a complexação dos metais no sistema podzolizado analisado, os AF são possivelmente as frações mais ativas ou reativas e estão contribuindo mais para as reações que ocorrem neste sistema ambiental.

Considerações Finais

Os solos estudados na micro-bacia correspondem a uma segunda geração de podzóis que está superimpondo sobre gleisolos. Tal processo de superimposição e a subsequente instalação da rede de drenagem atual é fortemente responsável pela evolução da pedo-paisagem da micro-bacia. A instalação e incisão da rede de drenagem na superfície do baixo plateau amazônico modifica os relevos e melhora as condições de drenagem dos solos mais profundos (Thick Podzol) localizados nas zonas de topo de colinas ou em remanescentes do plateau, e expõe nas encostas os saprolitos hidromórficos que são superimpostos pela podzolização dando origem aos podzóis hidromórficos e criptopodzóis, como os encontrados na micro-bacia estudada.

Embora a evolução da pedo-paisagem não tenha relação direta com as SH presentes nos solos da micro-bacia, a sequência e as características dos solos, que se configuraram a partir desta evolução respondem pelo tipo de distribuição das SH na sequência de solos estudados. A diferença textural dos solos de montante à jusante da encosta, as características de porosidade e variação do lençol durante o ano, nos solos, estabeleceram a regra de distribuição de AF e AH tanto na sequência dos perfis na encosta, quanto nos horizontes, para cada perfil de solo.

Assim é que a condensação e aromaticidade do AF tende a decrescer no sentido da jusante da encosta, partindo de um polo mais arenoso para um polo menos arenoso e de um ambiente mais seco para um ambiente constantemente encharcado de água. Às características que determinam a distribuição das duas frações húmicas na encosta, acrescenta-se a porosidade, a presença ou não de água nos horizontes dos perfis de solos e a flutuação do nível do lençol nos horizontes para explicar a distribuição de FA e HA nos horizontes de cada perfil de solo. Desta maneira, para o AF acredita-se que:

1) porosidade baixa leva à maior condensação na zona de batimento do lençol ou em ambiente seco eventualmente visitado pela água;

2) pedoambientes pouco porosos e secos levam à diminuição da condensação, portanto esta depende da flutuação do lençol para aumentar;

3) orosidade baixa nos horizontes da zona de oscilação do lençol influi positivamente a aromaticidade nos pedo-ambientes frequentemente úmidos ou secos com visita eventual da água; 4) porosidade desempenha papel secundário para a aromatização e condensação nos ambientes muito encharcados de água.

Para o HA os resultados e interpretações revelaram que:

1. A aromaticidade nos horizontes dos perfis dos solos relaciona-se aos meios mais porosos e independe da oscilação da água do lençol; 

  Figura 1: Características morfológicas dos principais tipos de horizontes orgânicos das florestas segundo Duchaufour (1960). Mull, Moder e Mor, e as camadas Ao, A1 e L (resíduo) F (fermentação), H (camada superficial completamente humificada) ........................................................................... Figura 2: Principais vias propostas para a formação de substâncias húmicas pela decomposição de resíduos animais e vegetais no solo. .................................................................................................. Figura 3:Estrutura química do ácido húmico proposto por Schulten e Schnitzer (1993) ................. Figura 4: Modelo estrutural propostos pela teoria macromolecular Schulten & Schnitzer (1997), em que as esferas azuis, vermelhas, brancas e pretas representam os átomos de carbono, oxigênio, hidrogênio e nitrogênio, respectivamente. As letras A, B e C indicam os espaços "vazios" presentes na molécula das SH capazes de interagir com outros compostos ...................................................... Figura 5: Esquema de estrutura das substâncias húmicas proposto por Simpson et al. (2002). As unidades vermelhas representam os cátions metálicos, as unidades pretas os polissacarídeos, as unidades azuis os polipeptídios, as unidades verdes as cadeias alifáticas e as unidades marrons os fragmentos aromáticos provenientes da lignina ................................................................................. Figura 1.6: Representação dos grupos cromóforos presentes nas substâncias húmicas .................... Capítulo 2

2 Figure 2 . 1 :

 221 Figura 1: Características morfológicas dos principais tipos de horizontes orgânicos das florestas segundo Duchaufour (1960). Mull, Moder e Mor, e as camadas Ao, A1 e L (resíduo) F (fermentação), H (camada superficial completamente humificada) ........................................................................... Figura 2: Principais vias propostas para a formação de substâncias húmicas pela decomposição de resíduos animais e vegetais no solo. .................................................................................................. Figura 3:Estrutura química do ácido húmico proposto por Schulten e Schnitzer (1993) ................. Figura 4: Modelo estrutural propostos pela teoria macromolecular Schulten & Schnitzer (1997), em que as esferas azuis, vermelhas, brancas e pretas representam os átomos de carbono, oxigênio, hidrogênio e nitrogênio, respectivamente. As letras A, B e C indicam os espaços "vazios" presentes na molécula das SH capazes de interagir com outros compostos ...................................................... Figura 5: Esquema de estrutura das substâncias húmicas proposto por Simpson et al. (2002). As unidades vermelhas representam os cátions metálicos, as unidades pretas os polissacarídeos, as unidades azuis os polipeptídios, as unidades verdes as cadeias alifáticas e as unidades marrons os fragmentos aromáticos provenientes da lignina ................................................................................. Figura 1.6: Representação dos grupos cromóforos presentes nas substâncias húmicas .................... Capítulo 2 Figure 2. 1: Location of the study area: a) Representation of the Brazilian Amazon basin; b) Soil distribution at the regional scale; c) Confluence of a small stream with blackish-brown waters and a river of clear colorless waters ............................................................................................................Figure 2. 2: Map of soil distribution in relation to the topography and vegetation ...........................Figure 2. 3: Soil distribution along two slopes ..................................................................................Figure 2. 4: Texture triangles for the soil profiles of the thick podzol (a), hydromorphic podzol (b), cryptopodzol (c), and gleysol (d) .......................................................................................................Figure 2. 5: Hypothetical model for the evolution of the studied catchment .....................................

Figure 2 . 2 :

 22 Figure 2. 1: Location of the study area: a) Representation of the Brazilian Amazon basin; b) Soil distribution at the regional scale; c) Confluence of a small stream with blackish-brown waters and a river of clear colorless waters ............................................................................................................Figure 2. 2: Map of soil distribution in relation to the topography and vegetation ...........................Figure 2. 3: Soil distribution along two slopes ..................................................................................Figure 2. 4: Texture triangles for the soil profiles of the thick podzol (a), hydromorphic podzol (b), cryptopodzol (c), and gleysol (d) .......................................................................................................Figure 2. 5: Hypothetical model for the evolution of the studied catchment .....................................

Figure 2 . 3 :

 23 Figure 2. 1: Location of the study area: a) Representation of the Brazilian Amazon basin; b) Soil distribution at the regional scale; c) Confluence of a small stream with blackish-brown waters and a river of clear colorless waters ............................................................................................................Figure 2. 2: Map of soil distribution in relation to the topography and vegetation ...........................Figure 2. 3: Soil distribution along two slopes ..................................................................................Figure 2. 4: Texture triangles for the soil profiles of the thick podzol (a), hydromorphic podzol (b), cryptopodzol (c), and gleysol (d) .......................................................................................................Figure 2. 5: Hypothetical model for the evolution of the studied catchment .....................................

Figure 2 . 4 :

 24 Figure 2. 1: Location of the study area: a) Representation of the Brazilian Amazon basin; b) Soil distribution at the regional scale; c) Confluence of a small stream with blackish-brown waters and a river of clear colorless waters ............................................................................................................Figure 2. 2: Map of soil distribution in relation to the topography and vegetation ...........................Figure 2. 3: Soil distribution along two slopes ..................................................................................Figure 2. 4: Texture triangles for the soil profiles of the thick podzol (a), hydromorphic podzol (b), cryptopodzol (c), and gleysol (d) .......................................................................................................Figure 2. 5: Hypothetical model for the evolution of the studied catchment .....................................

Figure 2 . 5 :

 25 Figure 2. 1: Location of the study area: a) Representation of the Brazilian Amazon basin; b) Soil distribution at the regional scale; c) Confluence of a small stream with blackish-brown waters and a river of clear colorless waters ............................................................................................................Figure 2. 2: Map of soil distribution in relation to the topography and vegetation ...........................Figure 2. 3: Soil distribution along two slopes ..................................................................................Figure 2. 4: Texture triangles for the soil profiles of the thick podzol (a), hydromorphic podzol (b), cryptopodzol (c), and gleysol (d) .......................................................................................................Figure 2. 5: Hypothetical model for the evolution of the studied catchment .....................................

Sumário

  Introdução .......................................................................................................................................... Introduction ........................................................................................................................................ Capítulo 1. Solos da bacia Amazônica, substâncias húmicas e técnicas espectroscópicas ............... 1.1. Solos da bacia Amazônica ....................................................................................................... 1.1.1. Solos Podzolizados .......................................................................................................... 1.1.2. Oxisolos ............................................................................................................................ 1.1.3. Acrissolos .......................................................................................................................... 1.1.4. Solos Hidromórficos: Gleissolos ...................................................................................... 1.2. Matéria orgânica do solo ....................................................................................................... 1.2.1 Classificação da Matéria Orgânica do Solo .....................................................................

  3. Os tipos de Húmus ............................................................................................................ 1.2.4. Substâncias Húmicas ........................................................................................................ 1.3. Caracterização das substância húmicas e técnicas espectroscópicas ........................................1.3.1 Espectroscopia de Absorbância de radiação no UltraVioleta-Visível ....................... 1.3.2.Espectroscopia de Fluorescência de Luz UV-Vísivel ........................................................ 1.3.3. Fluorescência quenching ................................................................................................. 1.3.4.Espectroscopia de Infravermelho com transformada de Fourier ..................................... Capítulo 2. Distribution of soils in a small catchment in the upper Negro River basin -Brazilian Amazonia and the steps of transformation of a podzolized pedo-landscape ..................................... 2.1. Introduction ............................................................................................................................. 2.3. Materials and methods ............................................................................................................ 2.3.1.Site identification and selection, field work, soil study, and sampling .............................. 2.3.2.Pedo-topographic mapping ............................................................................................... 2.3.3.Laboratory procedures: particle size and carbon contents ............................................... 2.4. Results ..................................................................................................................................... 2.4.1. Soil coverage and groundwater levels .............................................................................. 2.4.2. Soil distribution along the slope ....................................................................................... 2.4.3.Variation of texture classes and carbon in soil profiles .................................................... 2.5.2. Modification steps of the pedo-landscape throughout the soil transformation ................ 2.6. Conclusion ............................................................................................................................... Capítulo 3. Characterization and distribution of humics substances of a podzolized soils system in Upper Rio Negro-AM ........................................................................................................................ 3.1. Introduction .............................................................................................................................

  3

  cette façon, le présent travail vise à étudier les étapes de transformation du paysage de grenouille et l'analyse des substances humiques des sols podzolisés d'un micro-bassin situé dans le bassin Alto Rio Negro de l'utilisation des méthodes spectroscopiques afin de comprendre les fonctions de différentes fractions de matière organique. Afin de faciliter les publications ultérieures dans les revues scientifiques, une partie de ce travail a été présentée sous la forme d'articles. Dans le premier chapitre, une brève revue bibliographique a été présentée sur les sujets suivant: les sols du bassin amazonien, le processus de podzolisation et les techniques spectroscopiques. Par la suite, trois chapitres sont présentés sous la forme d'articles: deux rédigées en anglais et un en portugais. Le deuxième chapitre intitulé "Distribution of soils in a small catchment in the upper Negro River basin -Brazilian Amazonia and the steps of transformation of a podzolized pedo-landscape" vise à examiner la répartition spatiale et les caractéristiques des sols et des gleysols podzols et de présenter les étapes de transformation pédo-paysage. Dans le troisième chapitre, "Characterization and distribution of humics substance of a podzolized soils system in Upper Rio Negro-AM", l'objectif est de caractériser la distribution d'acides fulviques et humiques par des analyses spectroscopiques de UV-Visible et FTIR. Dans le quatrième chapitre, "Constante de Estabilidade (K) condicional e constante da capacidade de complexação para Cu(II) e Al(III) em amostras de ácidos fúlvicos e húmicos de solos podzolizados da bacia do Alto Rio Negro-AM, Brasil ", l'objectif est d'identifier les composants de fluorescence présents dans les substances humiques des podzols du micro bassin et d'évaluer les constantes de stabilité conditionnelle (K) et la capacité de complexation (CC) des composants fluorescents présents dans les acides fulviques et humiques vis à vis du Cu (II) et de l'Al (III) puis comparer avec les groupes fonctionnels observés en FTIR Les annexes, les données des extraits d'acides fulviques et d'acides humiques des sols sont accessibles pour consultation. Capítulo 1. Solos da bacia Amazônica, substâncias húmicas e técnicas espectroscópicas Neste capítulo, foi realizado o levantamento bibliográfico acerca dos temas tratados no trabalho. A fundamentação teórica trata sobre solos presentes nos baixos platôs da bacia do alto Rio Negro, os Oxisolos, os Podzóis, os Acrissolos (classificação da FAO) e os solos hidromórficos (DO

  Figura 1: Características morfológicas dos principais tipos de horizontes orgânicos das florestas segundo Duchaufour (1960). Mull, Moder e Mor, e as camadas Ao, A1 e L (resíduo) F (fermentação), H (camada superficial completamente humificada)

Figura 3 :

 3 Figura 3:Estrutura química do ácido húmico proposto porSchulten e Schnitzer (1993) 

Figure 2 .

 2 Figure 2. 1: Location of the study area: a) Representation of the Brazilian Amazon basin; b) Soil distribution at the

figure 2 .

 2 figure 2. The studied catchment that is located on the southern flank of a flat hilltop. This figure shows the soil distribution in relation to the topography and vegetation. The altitude ranges between 79 and 89 m and its declivity increases towards the center of the catchment. The northern portion of the mapped area corresponds to the nearly flat top of the hill. The southern slope presents, in sequence, convex, slightly straight, and concave segments and is drained by a stream of blackish-brown waters; at the southern end, outside of the catchment, this drainage flows into a stream of clear colorless water.

Figure 2 . 2 :

 22 Figure 2. 2: Map of soil distribution in relation to the topography and vegetation

Figure 2

 2 Figure 2. 3: Soil distribution along two slopes

Figure 2 .

 2 Figure 2. 4: Texture triangles for the soil profiles of the thick podzol , hydromorphic podzol, cryptopodzol, and gleysol.

  the previous and the current reliefs of the hilltop and the slopes. This type of extreme evolution has been observed by[START_REF] Do | Podzolization as a deferralitization process: A study of an Acrisol-Podzol sequence derived from Palaeozoic sandstones in the northern upper Amazon Basin[END_REF] in the Jaú River basin, AM and by[START_REF] Dubroeucq | From Oxisols to Spodosols and Histosols: evolution of the soil mantles in the Rio Negro basin (Amazonia)[END_REF] in the upper Negro River basin. The geometric relationships between the studied soils are also evidence of the genetic relationships distributed over time and their repercussions for the development of the pedo-landscape. The evolution of this pedo-landscape also reflects the transition of clayey soils into soils of intermediate/sandy texture, which are gradually superimposed by podzolization. The spatial distribution of the soils presented in figures 2.2 and 2.3 reflects this textural change and the change in the pedo-landscape over time, aided by the presence and evolution of the drainage system.

Figure 2 . 5 :

 25 Figure 2. 5: Hypothetical model for the evolution of the studied catchment

  plants) of different natures and in different stages of decomposition due to chemical and biological degradation via microorganisms (PLAZA; D'ORAZIO;[START_REF] Plaza | Copper(II) complexation of humic acids from the first generation of EUROSOILS by total luminescence spectroscopy[END_REF]. Based on its degree of decomposition, the organic matter can be classified as follows: a) litter b) non-humic substances, and c) humic substances(STEVENSON, 1994).Humic substances (HS) are complex and heterogeneous mixtures of polydisperse materials formed by chemical and biochemical reactions during the decay of plants and microbial moieties (MUSCOLO; SIDARI; NARDI, 2013). The humic substances have different chemical and physical characteristics according to their solubility: the humic acids (HA), fulvic acids (FA) and humine (Hu)(STEVENSON, 1994). HS are important soil components because they affect the physical and chemical soil properties(STEVENSON, 1994), improve soil fertility, and contribute to metal bioavailability and transport(STEVENSON, 1994). HS may influence the soil sorption mechanism of organic and inorganic gases present in the atmosphere in addition to contributing to the soil genesis mechanisms (AZEVEDO; RODRIGUES DE; NOZAKI, 2008). Knowledge of the HS dynamics is of scientific interest and may contribute to the understanding of soil development as well as the soil cycle and carbon storage.

  .1B) with more than 97 cm thickness in the middle slope. Finally, a crytopodzol, in the sense of Duchaufour (1997), located on the lower slope is named profile 3 (P3) (Figure3.1B). A forest called Campinarana covers the thick podzol and the hydromorphic podzol. The cryptopodzol is covered by a transition between forested Campinarana and Terra Firme[START_REF] Sena | Os solos e geoambientes das campinaranas Amazônicas: Relação Genética entre os geoambientes e a evolução da paisagem em um transecto na bacia do alto Rio Negro[END_REF].

Figura 3. 2 :

 2 Figura 3. 2: Soil distribution in relation to the topography and characteristics of horizons

Figura 3. 3 :

 3 Figura 3. 3: The United States dept of agriculture (USDA) soil texture triangle with the percent of sand, clay and silt in the samples

Figura 3. 4 :

 4 Figura 3. 4: Distribution of C in soil (bar left scale) and C in humic substances (line, right scale)

Figura 3. 5 :

 5 Figura 3. 5: E2/E3 and E4/E6 ratios for the fulvic and humic acid extracts and their respective distribution among the soil horizons and the group 1 (red, plain) 2 (red, dashed), 3 (black dashed) and 4 (black plain) representing zone of

Figura 3. 6 :

 6 Figura 3. 6: Distribution to (E 2 /E 3 )/(E 4 /E 6 ) ratio in soils profiles in Fulvic acid (A) and humic acid (B)

Figura 3. 7 :

 7 Figura 3. 7: The behavior of E 2 /E 3 ratio, E 4 /E 6 ratio and the Silt/ Cos in FA and HA different profiles and soils horizons

(

  Figura 3. 8: FTIR spectrum of profile 1 humic acid samples and band of interest

Figura 3

 3 Figura 3. 9: A, B, C, D, E and F: Distribution of wavelength intensity, selected in soil profiles and horizons

  2 in BhsP3 followed by A11P3 (ABS = 0.19), while A/EP3 and Cg2P3 have the lowest values (ABS = 0.1). FA in profile P1 has the highest intensities, and A12P1 has the higher absorbance (ABS = 0.31). The lowest intensities are in the P2 profile, with the smallest in the BhP2 horizon. Therefore, FA has the highest intensities of carboxylic group compared to HA. The distribution of this functional group along the profile is

  The second subgroup (left S) has only one horizon (A12P3). It is influenced by the functional group and E4/E6 index from left quadrante S and secondarily by the E2/E3 index and porosity (SiltCos). The third subgroup is located in the left S near the axis origin. It is formed by Cg1P3, Cg2P3, E1P1 and E2P1 and they are under E4/E6 index, intensity of functional groups (C=C aromatic, C-O ether/alcohol, C-O polysaccharide and C=O carboxylic), E2/E3 index and porosity influence. In this subgroup are the horizons whose HA has greater condensation and aromaticity; this ACP analysis refers to interpretations made from UV-Vis results. In group B (A12 P1 , EBh P1 , Bh P1 and A11 P3 ), left S, only HA is present with a large influence of E4/E6 ratio and intensity of the functional groups (C=C aromatic), (C-O ether/alcohol), (C-O polysaccharide) and (C=O carboxylic) and secondarily by the variable from right quadrant S. FA present in group A has different behavior, according to their positions in the quadrant. Horizons A12P1 and AP2 form a subgroup that is slightly influenced by the variables (-CH -aliphatic); (-OH) and the functional groups and E4/E6 index of the left quadrant S; in fact they are horizons with low condensation (high E4/E6 index) and with high intensity (-OH) and (-CH), slightly high. The horizons Bhs P3 and Cg1 P3 are close to the origin axis and, unlike the two previous horizons, have high condensation (low E4/E6 index) and high aromaticity (low E2/E3 index), having low (-OH) and low aliphatic intensities, as well as high intensities of the functional groups (C = C -aromatic); (C-Oether/alcohol); (C-O-polysaccharide); (C = O-carboxylic acid). The horizons A1 P1 , close to the origin axis, are in the right quadrant S, and correlate directly with the aromatization index (E2/E3) as well as

Capítulo 4 .

 4 Constante de Estabilidade condicional (K) e constante da capacidade de complexação (CC) para Cu 2+ e Al 3+ em amostras de ácidos fúlvicos e húmicos de solos podzolizados da bacia do Alto Rio Negro-AM, Brasil Resumo: As substâncias húmicas (SH) possuem a habilidade de formar complexos estáveis com os íons metálicos nos meios naturais devido a presença dos grupos funcionais, principalmente os carboxílicos e fenólicos. Daí a importância das SH nos solos podzolizados. Por outro lado as SH tem propriedades fluorescentes quando excitadas por radiação eletromagnética; alguns metais têm a propriedade de diminuir ou de aumentar a fluorescência. Neste estudo o objetivo é identificar as componentes fluorescentes, presentes nas substâncias húmicas de amostras dos solos podzóis na Bacia do Alto Rio Negro-AM, avaliar as capacidades e constantes de complexação destes componentes com os metais Cu 2+ e Al 3+ e comparar com os grupos funcionais obtidos com a FTIR os resultados de complexação. A medida da fluorescência das SH sem complexação e com complexação pelos metais em diferentes concentrações (0 a 105.9 mg/L), foi realizada utilizando um fluorímetro modelo Hitachi. A determinação das constantes de estabilidade condicional (K) e capacidade de complexação (CC) foi realizada de acordo com o modelo proposto por Ryan and Weber (1982) e os espectros 3D (EEM) das amostras foram tratados com o modelo estatístico do CP/PARAFAC. Com os resultados dos espectros de fluorescência aliados à análise CP/PARAFAC

  Quatro gramas (4 g) de solos foram misturadas a 1 mol L -1 HCl com uma relação líquido/sólido (L/S) = 10 e centrifugada a 433 ms -2 para separar o sobrenadante do precipitado. Na sequência, o sobrenadante foi neutralizado utilizando NaOH 1 mol.L -1 ; logo após o resíduo foi removido do sobrenadante por centrifugação (11180 ms -2 ). O sobrenadante foi redissolvido com HCl 6 mol L -1 e encaminhado novamente para a centrifugação (11180 ms -2 ), o sobrenadante é o ácido fúlvico (FA) e o precipitado o ácido húmico (HA). O HA foi redissolvido com NaOH 0,1 mol L -1 e seguiu para purificação em filtro de polietersulfona, com o objetivo de remover a sílica e a argila ainda presentes na solução. Após a filtração, o HA foi transferido para a membrana de celulose para diálise. A diálise foi realizada com água deionizada até que a água apresentasse teste negativo para íons cloreto (Cl -). O FA foi purificado em resina de adsorção, primeiro na resina DAX-8 e na sequência, com a resina saturada com íons H + . Todas as extrações foram encaminhadas para a liofilização e na sequência para a análise de fluorescência.

4. 2 . 3

 23 Análise do quenching de fluorescência e modelo PARAFACQuando a fluorescência espectroscópica é aplicada torna-se importante compreender que a intensidade de fluorescência é proporcional à concentração do fluoróforo em soluções muito diluídas (absorbância muito baixa) em relação a lei de Beer Lambert. Para concentrações suficientemente baixas (absorbância a 250 nm < 0.1) a luz incidente é ligeiramente e linearmente atenuada ao longo do caminho ótico. Já em concentrações altas, uma parte significativa da luz incidente é absorvida antes de chegar ao ponto onde a fluorescência é observada, assim a luz absorvida não é linear com quantidade de cromóforo, este efeito é conhecido como efeito de filtro interno (Inner Filter Effect) (LUCIANI; REDON; MOUNIER, 2013). Com o objetivo de diminuir tal efeito 5 diluições (50; 25; 12,5; 6,25 e 3,13 mg.L -1 ) foram preparadas com água Milli-Q e aplicadas às amostras antes do experimento de quenching de fluorescências(MILORI et al., 2002; MOUNIER;[START_REF] Mounier | Differentiation of organic matter's properties of the Rio Negro basin by crossflow ultra-filtration and UV-spectrofluorescence[END_REF] 

Figura 4. 1 :

 1 Figura 4. 1:Comportamento da intensidade de fluorescência das SH no decorrer do experimento de fluorescência quenching

A

  determinação dos parâmetros de complexação (constante de estabilidade condicional e Capacidade de Complexação) foi realizada através da aplicação de dois modelos simples e independentes de interação entre o sítio de complexação e o metal, baseado no princípio de Ryan and Weber (1982), um modelo de ligação um metal/um ligante (1:1) e um modelo com um metal/dois ligantes (1:2). Estes modelos são regidos pelas seguintes equações químicas: L1+M ↔ ML1 (1) Onde L1 é o sítio de complexação livre, ML1 o complexo metálico e M o metal livre M=Cu ou Al. Estes equações são controladas pelas constantes termodinâmicas de equilíbrio: foi testado, ele considera dois sítios de complexação independentes: L1+M ↔ ML1 e L2+M ↔ ML2 (5) Onde L1 e L2 são os sítios de complexação livre; ML1 e ML2 os complexos metálicos com os sítios L1 e L2, respectivamente e M=Cu ou Al. O equilíbrio termodinâmico entre os dois sítios é controlado pelas seguintes equações: K1

  Considerando que L1, L2, ML1 e ML2 tem rendimento quântico de fluorescência individual ΦL1, ΦL2, ΦML1 and ΦML2 respectivamente. Com estes parâmetros é possível calcular teoricamente a resposta de fluorescência IF 1:1 =f(L 1 , K 1 , M 0 ) and IF 1:2 =f(L 1 , L 2 , K 1 , K 2 , M 0 ) e o BIAS para otimizar as funções seguintes : BIAS1:1=Σ[(IFi-IF1:1(CL1,K1,M0i)/IFi] 2 (9) BIAS1:2=Σ[(IFi-IF1:2(CL1,CL2,K1,K2,M0i)/IFi] 2(10) 

  complexação com o valor do BIAS, definido como a soma das distâncias entre o valor experimental e o valor do modelo de cada experimento de fluorescência quenthing. Os valores obtidos para o BIAS do modelo 1:1 e do modelo 1:2 são apresentadas na figura 4.2.

Figura 4. 2 :

 2 Figura 4. 2: BIAS do modelo 1:1 e 1:2 para a componente 1 com metal Cu 2+ (A), componente 2 com metal Cu 2+ (B), componente 1 com metal Al 3+ (C) e componente 2 com o metal Al 3+ (D)

Figura 4. 3 :

 3 Figura 4. 3: Espectros das 7 componentes obtidas após o tratamento PARAFAC.

Figura 4. 4 :

 4 Figura 4. 4: Distribuição das componentes entre os horizontes dos solos e os metais.C1: componente PARAFAC 1 e C2: Componente PARAFAC 2

Figura 4. 6 :

 6 Figura 4. 6:Distribuição dos valores da constante K para as componentes 1 e 2 nos AF e AH com adição de Al 3+ com seus respectivos grupos

Figura 4. 7 :

 7 Figura 4. 7:Distribuição da capacidade de complexação (CC) nos AF e AH com os metais Cu 2+ e Al 3+

Figura 4

 4 Figura 4. 8: A, B, C, D, E and F, distribuição da intensidade do comprimento de onda dos grupos funcionais nos AF e AH dos horizontes dos três perfis de solo estudados

Figura 4. 9 :

 9 Figura 4. 9:Análise das componentes principais para pc1 e pc2 das constantes K, CC, distribuição dos grupos funcionais e das relações E2/E3 e E4/E6 . As letras A, B, C, D, E, F e G indicam as componentes CP-PARAFAC

  Figura 4.9B) indicou que os AH possuem maior importância com relação aos grupos funcionais, por isso as amostras seguiram esta tendência. Para os AF a maior importância foi com relação às constantes logK e CC, indicando que estas constantes aumentam nos AF. A segunda projeção (figura 4.10A) representa a variância de 33,58% dos eixos pc2 e pc3. Observa-se que os grupos funcionais (C-CAr) e (COOH) (superior esquerdo) com o logK (inferior direito) não são correlacionáveis. O mesmo acontece com grupos funcionais C-OAl C-Cpol e o índice E4/E6 (inferior esquerdo) com a constante CC. Nesta projeção é possível observar que as constantes logK e CC são em parte, não correlacionadas com os grupos funcionais. Entretanto, observa-se correlação positiva entre CC e COOH, C-CAr e o índice E2/E3, e correlação negativa com CH; OH e logK. Por outro lado, existe correlação positiva entre CH; OH e logK e COAl, C-Cpol e E4/E6. Estes últimos correlacionam negativamente com COOH, C-CAr e o índice E2/E3.

  Figura 4. 10:Análise das componentes principais para PC3 e PC2 das constantes logK , CL e da distribuição dos grupos funcionais e das relações E2/E3 e E4/E6

  quenching de fluorescência, por meio da análise das constantes de estabilidade condicional e da capacidade de complexação, das substâncias húmicas extraídas de solos podzolizados da bacia do Rio Negro, podem contribuir para o entendimento do papel da matéria orgânica nos pedo-ambientes. O estudo ressaltou a diferença dos fluorófaros existentes nos AF e AH, e revelou valores das constantes logK variando de 3,66 a 5,00, e CC variaram de 3, 83.10 -10 mol.mgC - 1 a 1, 06.10 -06 mol.mgC -1 . Os resultados refletem, também, significativa correlação entre a complexação e os grupos funcionais.Dois comportamento podem ser indicados com base nas constantes analisadas:A constante logK indicou diferenças entre a força de ligação das SH com os metais Cu 2+ e Al 3+ , para o primeiro as constantes foram em média maiores, indicando que como o maior número de grupos funcionais das MO tem maior força de ligação com o Al 3+ , onde a força de ligação foi menor. Isso pode ocorrer porque os sítios disponíveis para tais ligações já foram ocupados com o metal. Para o Cu 2+, comportamento da constante foi mais variável no caso das amostras analisadas, isso significa que ainda existam sítios de ligação disponíveis em alguns horizontes dos solos. As diferenças entre os AF e AH neste caso, foi que os AF possuem valores muito mais variados da constante que os AH, para ambos os metais.A Capacidade de Complexação (CC) possui uma diferença clara entre os AF e AH. Os AF possuem valores levemente maiores que os AH, o que indica maior capacidade de complexação para a primeira fração. Os metais analisados (Cu 2+ e Al 3+ ) não indicaram grandes diferenças.

  Foge a esta distribuição os horizontes pouco porosos e menos úmidos a secos, da base do perfil P3 (Cg1; Cg2 e Cg3), que localizam-se na jusante da encosta, e que apresentaram altas condensação e aromaticidade. Depreende-se disto que o AF torna-se mais condensado e mais aromático em pedo-ambientes menos úmidos. Para o AH a condensação e aromaticidade aumentam do topo para a parte mediana da encosta, decrescendo, posteriormente no sentido da base da encosta. Os AH nos horizontes Cg1; Cg2 e Cg3 fogem a esta distribuição; são mais condensados e menos aromáticos. Disto decorre que para o AH altos indices de condensação e aromaticidade são fortemente influenciados por pedo-ambientes temporariamente úmidos como os do P2 localizado na meia encosta. As análises UV-Vis dão conta que nestes pedoambientes, representados pelos três perfis o AF é mais condensado e mais aromático do que o AH.

  

  

  

  

  

  

  

  

  .2. Materials and methods ............................................................................................................ 3.2.1.Environmental setting ........................................................................................................ 3.2.2. Soil study and soils samples ............................................................................................. 3.2.3. Extraction and fractionation of Humic Substances .......................................................... 3.2.4. Particle size analysis and pH ...........................................................................................

	3.

  . Spectroscopic analyses ..................................................................................................... 3.3.Results and discussion .............................................................................................................. 3.3.1. Soils horizons characterization: morphology, texture; groundwater and pH .................. 3.3.1.1.Morphology of soils ........................................................................................................

3.3.2.Carbon content of soils

and humic substances .................................................................. 3.3.3.UV-visible spectroscopy: indices E2/E3 and E4/E6 ............................................................. 3.3.4. Infrared Spectroscopy in humic substances ..................................................................... 3.3.5.Statistical considerations ................................................................................................... Capítulo 4. Constante de Estabilidade condicional (K) e constante da capacidade de complexação (CC) para Cu 2+ e Al 3+ em amostras de ácidos fúlvicos e húmicos de solos podzolizados da bacia do Alto Rio Negro-AM, Brasil ............................................................................................................... 4.1. Introdução ............................................................................................................................... 4.2.Materiais e Métodos ................................................................................................................. 4.2.1. Área de estudo e coleta de amostras ................................................................................ 4.2.2. Extração das Substâncias húmicas ................................................................................... 4.2.3 Análise do quenching de fluorescência e modelo PARAFAC ........................................... 4.3. Resultados e Discussão ......................................................................................................... 3.1. Componentes fluorescentes dos AF e AH extraídos dos solos ......................................... 4.3.2. Estudo das constantes de complexação .......................................................................... 4. 3.3. Espectroscopia de Fluorescências ................................................................................ 4. 3.4 Relação das Constante de Estabilidade e Capacidade de Complexação dos AH e AF em relação com os metais e grupos funcionais. ............................................................................. 4. 4. Conclusão ............................................................................................................................. Considerações Finais...................................................................................................................... Referências Bibliográficas ............................................................................................................... Anexos .............................................................................................................................................

  biochimiques lors du processus de dégradation et de transformation de la matière organique par le procédé d'humification, provenant des plantes et des organismes ajoutés aux sols (MUSCOLO; SIDARI; NARDI, 2013). Selon leur degré de solubilité, on peut les diviser en: acides fulviques (AF),

acides humiques (AH) et humine (HU). Connaître le comportement SH dans l'environnement pédologique contribue à comprendre la dynamique de la MOS, car elles jouent un rôle important dans l'environnement, agissant à la fois sur les propriétés chimiques et physiques des sols. Dans certains types de sols, la matière organique dissoute (MO) est mobilisée et peut précipiter en profondeur (BUURMAN, JONGMANS, 2005), comme dans le cas des podzols. Les principales caractéristiques des podzols sont la présence d'un horizon éluvial (E), de couleur grise, avec des teneurs en cations basiques, Al, Fe et matières organiques, en faible quantité, et avec Si sous forme de quartz résiduel en grande quantité, et (B), enrichi en Al, Fe et matière organique (BUURMAN; JONGMANS, 2005; LUNDSTRÖM;

  Table1provides the values obtained for the total C content in the clay fraction (≤ 0.002 mm) of the soil samples, with no pre-treatment.

	Tabela 2 1: Texture triangles for the soil profiles of the thick podzol (a), hydromorphic podzol (b), cryptopodzol (c),
	and gleysol (d)		
		Horizons Depth. (cm) C (%)
		A	0-13	50.46
	Deep podzol	AE	13-45	48.84
		E2	73-153	10.06
		Bh	153+	38.4
		A	0-20	58.92
	Hydromorphic podzol	AE	20-42	42.54
		E	42-97	16.31
		Bh	97+	29.14
		A	0-22	52.28
	Criptopodzol	Bh3	22-34	44.48
		Bh2	34-53	46.69
		EBh	53-72	32.56
		CBhs	72+	10.49
		A	0-11	14.04
	Gleysol	ABhs	11-34	9.56
		Cg1	34-64	4.78
		Cg2	64-84	3.38

Table 1

 1 

-Silt/CoS ratio). Figures 3.6 and 3.7 show that the E1P1, E2P1 and EBhP1 horizons have more condensed and aromatic FA, except EBhP1, which is less aromatic than the first two

  , esta interação pode afetar diretamente diversas funções nos solos como

	por exemplo, a forma, distribuição, biotoxicidade, migração e transformação dos materiais orgânicos
	e minerais (YAMASHITA; JAFFÉ, 2008).
	A presença dos grupos funcionais imprime nas SH propriedades fluorescentes, que refere-se
	a capacidade óptica de emitir luz quando exposta a radiações (COBLE, 2007). O fenômeno de
	fluorescência é provável em sistemas moleculares que contêm átomos com pares solitários de
	elétrons, tais como: C = O, aromáticos, fenólicos, quinonas e, sistemas alifáticos conjugados
	insaturados rígidos, presentes nas SH (PLAZA; D'ORAZIO; SENESI, 2005; SENESI, 1990).
	Devido a tais características a fluorescência tornou-se uma técnica comumente utilizada nos
	estudos que envolvem o interesse nas propriedades estruturais e nas funções químicas das
	SH(PLAZA; D'ORAZIO; SENESI, 2005; SENESI, 1λλ0). Durante a fluorescência as moléculas são

  Cu 2+ é preferencialmente ligado aos grupos funcionais carboxílicos, principalmente em altas concentrações do metal. No entanto poucos trabalhos associando a interação das SH com os metais foram realizados em amostras de solos de ambientes tropicais.Mounier et al. (2010), apresentou um estudo de complexação na matéria orgânica dissolvida (MOD) nas águas de um igarapé na região do Alto Rio Negro-AM, e do comportamento da fluorescência quenching frente a adição de Cu 2+ e identificou as constantes de fluorescência para a matéria orgânica dissolvida (MOD).Este trabalho tem como objetivo o estudo da capacidade de complexação das substâncias húmicas ( ácidos fúlvicos e húmicos) de amostras de solos podzóis na Bacia do Alto Rio Negro, através da identificação das componentes fluorescentes das SHs, da avaliação das capacidades e constantes de complexação destas substâncias com os metais Cu 2+ e Al 3+ , e da comparação com os grupos funcionais obtidos com a fluorescência de Infravermelho com transformada de Fourier (FTIR) que foi o objeto de estudo do capítulo 3. O Cu 2+ foi escolhido devido aos modelos apresentados em muitos estudos de fluorescência e o Al 3+ devido a sua participação geoquímica nos ambientes de solos

	horizontes: A11, A12, A/E, Bhs, Cg1, Cg2 e Cg3. O perfil 1 está localizado na alta vertente enquanto
	o perfil 2 e o 3 estão localizados na média e baixa vertente. Os perfis de solo possuem diferentes
	características texturais. Nos perfis P1 e P2 todos os horizontes possuem textura arenosa com o
	mineral de quartzo prevalecendo de maneira residual, no P3 a textura varia de arenosa nos horizontes
	A11, A12 e A/E, areia franca nos horizontes Bhs e Cg1 e franco arenosa nos horizontes Cg2 e Cg.
	As condições de variação do nível do lençol freático não são as mesmas durante o ano na região, por
	essa razão durante o período de coleta das amostras de solo (novembro/dezembro 2013) o topo do
	lençol freático não foi prospectado no P1; no P2 estava a 55 cm e no perfil 3 foi encontrado a 33 cm
	(descrição completa da dinâmica do lençol no capítulo 3).
	4.2.2. Extração das Substâncias húmicas
	Após a coleta, as amostras de solo foram secas ao ar, passadas na peneira de 2 mm, moídas e
	seguiram para o procedimento de fracionamento e purificação das substâncias húmicas realizado a
	partir do princípio de diferença de solubilidade recomendado pela Sociedade Internacional de
	ácidos. Substância Húmicas (PERDUE; PERDUE, 2012).
	4.2.Materiais e Métodos
	4.2.1. Área de estudo e coleta de amostras
	O sítio de estudo encontra-se localizado no município de São Gabriel da Cachoeira, Alto Rio
	Negro, Amazonas (latitude 0° 14ʾ S e longitude 66° 47ʾW). O clima da região é tipicamente quente
	e úmido classificado como tipo Af (tropical chuvoso de floresta), com temperatura média anual de
	25 ° C e precipitação em torno de 3000 mm (W. Köppen -Geiger, 1846-1940). O relevo é constituído
	por planaltos de baixa altitude que exibem homogeneidade altimétrica (interflúvios tabulares e colinas
	de altura entre 80 e 100 m ) (FRANCO; MOREIRA; BARBOSA, 1977).
	A transecção de solos possui três perfis e encontra-se em uma vertente retilíneo-convexo-
	côncava de aproximadamente 75 m de comprimento, em uma microbacia cujo principal igarapé
	possui águas pretas. A descrição precisa do sítio de estudo pode ser encontrada no capítulo 3.
	Os solo foram caracterizados em trincheiras abertas e classificados de acordo com a FAO
	, desenvolveram estudo em ácidos fúlvicos (AF) fluviais o (2006). No total foram coletadas 18 amostras de solos que se distribuem: no perfil 1 (P1) classificado
	qual permitiu associar a mudança do comportamento da fluorescência com a adição de Al 3+ ,tal como Podzol bem drenado, com a presença dos horizontes: A11, A12, E1, E2, EBh e Bh. O perfil 2
	estudo associou a afinidade dos grupos funcionais fenólicos e -OH stretch com a complexação do (P2), Podzol hidromórfico, com os horizontes: A, A/E, E1, E2 e Bh e o terceiro perfil (P3)
	metal Al 3+ . Lu and Allen (2002) em estudos com matérias orgânicas dissolvidas sugeriram que o denominado de Criptopodzol (no sentido de DUCHAUFOUR,1997), com sequência de sete

  ). Esta componente prevalece, também, no Bhs, Cg1 e Cg2 do P3 tanto com o metal Cu 2+ como com o Al 3+ em C1; as componentes B e C distribuem-se em todos os horizontes dos três perfis para AF, e podem estar tanto em C1 como em C2. Nos AH a componente G prevalece em todos os horizontes dos solos tanto para o metal Cu 2+ como para o metal Al 3+ em C1, exceto no horizonte BhP2. As componentes D, E e F predominam nos horizontes de todos os perfis, para AH em C2, tanto para Cu 2+ como para Al 3+ (Figura 4.4).Aparentemente não parece haver uma regra para a distribuição dos fluoróforos nos horizontes dos perfis de solo. A nítida diferença entre os AF e AH está ressaltada. Algumas diferenças podem ser apontadas pelo aparecimento de diferentes fluoróforos em relação ao metal Cu 2+ ou Al 3+ ; isso pode ocorrer devido as diferentes ligações entre os grupos funcionais presentes nas SH e os íons metálicos (ELKINS;[START_REF] Elkins | Fluorescence and FT-IR spectroscopic studies of Suwannee river fulvic acid complexation with aluminum, terbium and calcium[END_REF], que evidenciam assim, tipos de fluorescência diferentes. distribuição dos logK Cu nos AF e AH apresentaram variações entre os perfis e os horizontes dos solos, tal distribuição permitiu uma divisão em quatro grupos (Figura 4.5): primeiro grupo (G1) apresentou amostras de AF que estão acima da linha de relação 1:1, ou seja, possuem para a C2 altos valores de logK Cu , é um grupo formado principalmente por horizontes de superfície dos três figura 6 apresenta o estudo da constante logK Al com a adição do Al 3+ . As constantes variaram no AF de 0.77 a 4.81 na C1 e de 0.81 a 6.41 na C2, para os AH os valores variaram de 3.66 a 4.96 na C1 e na C2 de 4.00 até 5.00 (Figura 4.6).

	4.3.2. Estudo das constantes de complexação
	perfis (A11P1,A12P1 e A12P3) exceto devido a presença do horizonte Cg3P3, o segundo grupo (G2) 4.3.2.1. Estudo da constante de estabilidade condicional (K) para Cu 2+ e Al 3+ apresenta os valores próximos à linha de relação 1:1, ou seja os valores da C1 e da C2 próximos, é
	O parâmetro de ligação K significa a constante de estabilidade condicional (CHEN et al., formado principalmente por amostras de AF tanto de horizontes de superfície como de horizontes de
	2003; SMITH; BELL; KRAMER, 2002), e é relacionada com a força de ligação dos sítios profundidade, neste grupo encontram-se apenas duas amostras de AH (E1P2,A12P3); o terceiro grupo
	complexantes disponíveis no sistema; para cada ligante existe uma constante de estabilidade (SMITH; (G3) apresentou valores abaixo da linha da relação 1:1, os valores da C1 são maiores que os valores
	BELL; KRAMER, 2002). da C2, é composto por amostras AF de subsuperfície (EBhP1, BhP1, BhsP3, Cg1P3 e Cg3P3) e a amostra
	de AH E2P1. O quarto grupo (G4), também apresentou valores próximos a linha 1:1, a diferença para
	o grupo dois e que os valores de C1 e C2 são maiores, além disso no grupo estão presentes o maior
	número de amostras de AH de horizontes variados, exceto pela presença do horizonte Cg2P3 de AF.
	Estudo anteriormente realizado para a determinação da fluorescência quenching da MO de
	solos franceses com textura arenosa, Merdy et al. (2009), encontrou valores de logKCu que variaram
	entre 2.2 a 3.0 com a adição do metal Cu 2+ e Mounier et al. (2011), nas MOD da microbacia deste
	estudo, encontrou valores de logKCu entre 2.8 e 3.9. Os valores da constante de logKCu são em média
	semelhantes aos dos solos podzolizados estudados, demonstrando que a força de ligação das matéria
	orgânicas possuem valores médios.

Os valores de logKCu no metal Cu 2+ obtidos para a C1 da EEM/CP-PARAFAC dos AF variaram de 1,29 a 5,19 e de 2,8 até 5,82 para a C2. Para os AH a C1 variou de 3,66 a 4,95 e a C2 variou de 2,56 a 5,33 (Figura 4.5). Figura 4. 5:Distribuição dos valores da constante K para as componentes 1 e 2 nos AF e AH com adição de Cu 2+ e sua distribuição em grupos A Observando a distribuição dos valores da constante logKCu dos horizontes dos solos nota-se que o AH apresentou maior homogeneização; a maior parte das amostras são encontradas no grupo 4, para o AF a variação dos valores de logKCu foi maior, e as amostras estão distribuídas entre os quatro grupos. A diferença dos valores obtidos entre os AF e AH demonstra que as moléculas de AF apresentam uma variedade maior de sítios de complexação que os AH. Possivelmente os AF não possuem os mesmoa sítios de complexação de Cu +2 que para os AH e possuem ainda, sítios disponíveis para complexação, já com os AH o comportamento foi diferente e mais homogêneo, o

que pode significar que os sítios de complexação disponíveis para ligação com Cu 2+ foram preenchidos, isso explica a maior parte das amostras estarem próxima a linha de modelagem.

A

  ).A tendência dos valores de logK Al permitiu identificar uma clara divisão com relação a força de ligação dos AF dos horizontes eluviais dos perfis P1 e P2 (G1) dos demais AF que estão presentes no G2 e G3. Os AH mais uma vez apresentaram valores homogêneos, para todas as amostras presentes no G2, significando que os sítio de complexação dos AH são semelhantes entre os perfis e os horizontes dos solos estudados para o metal Al 3+ ; já para os AF existem diferenças nas força de ligação entre os sítios disponíveis nos horizontes dos solos e os metais.Estudos da fluorescência quenching com o metal Al3+ , Ryan et al,1996 (apud KELLY M. ELKINS; NELSON, 2002) dos podzóis apresentou valores de logKAl em torno de 5.79, em pH 4, os valores de padrões oferecidos pela IHSS enumerou que logKAl de amostras com pH entre 4 e 5 variam de 4.67 a 6.45. As amostras de AH analisadas neste trabalho apresentaram resultados que estão dentro da faixa daqueles encontrados na bibliografia; no caso dos AF algumas amostras apresentaram valores fracos de logKAl . Mais uma vez, os AF apresentaram uma grande variabilidade de tipo de força de ligação do que para AH.Entre os metais a tendência de logK não foi a mesma entre os AF e AH e entre os metais. De maneira geral, os valores obtidos para o Cu 2+ são levemente maiores que os de Al 3+ , possivelmente porque os sítios de complexação das amostras disponíveis para a ligação com o metal Al 3+ já foram ocupados do que os sítios disponíveis para o Cu 2+ , tal comportamento pode ocorrer devido às diferenças de ligação entre os metais e os grupos funcionais das SH que são responsáveis pela complexação destes metais; o Cu 2+ possui uma tendência de realizar ligações com os grupos funcionais carboxílicos[START_REF] Lu | Characterization of copper complexation with natural dissolved organic matter ( DOM )-link to acidic moieties of DOM and competition by Ca and Mg[END_REF][START_REF] Lu | Characterization of copper complexation with natural dissolved organic matter ( DOM )-link to acidic moieties of DOM and competition by Ca and Mg[END_REF] e o Al 3+ tem uma tendência de complexação com grupos fenólicos (ELKINS;[START_REF] Elkins | Fluorescence and FT-IR spectroscopic studies of Suwannee river fulvic acid complexation with aluminum, terbium and calcium[END_REF], apesar da afinidade com o grupo funcional carboxílico, no entanto esta diferença de comportamento responde pelos diferentes valores de logK entre os metais e também entre as SH, já que para os AF os valores foram mais heterogêneos do que para os AH para ambos os metais, demonstrando uma variedade de comportamento dos sítios de ligação dos AF.

	4.3.2.2. Estudo da Capacidade de Complexação para Cu 2+ e Al 3+
	A capacidade de complexação (CC) indica a capacidade do sistema em formar complexo em
	relação à quantidade de carbono (C) das SH (RYAN '; WEBER, 1λ82; YAMASHITA; JAFFÉ,

  2. Nos meios temporariamente mais úmidos a aromaticidade é maior; 3. Nos ambientes secos e argilosos aromaticidade é menor 4. Maior condensação independe da porosidade, na zona de oscilação do lençol, mas depende de maior porosidade em horizontes com água permanente.Os AF estudados são mais condensados e aromáticos do que os HA. Entretanto os AF têm, principalmente, caráter hidrofílico e alifático, e secundariamente o caráter é dado pela presença das funções aromática e carboxílica. O AH por sua vez é possui caráter definido pelas funções polisacarídio e ether-alcool, mas, secundariamente, seu caráter é também alifático e hidrofílico.O caráter imposto pelos grupos funcionais ajudam a entender a capacidade de complexação dos AF e AH com os metais Cu +2 e Al +3 , obtidas com o experimento realizado.Os AH apesar de serem melhor co-relacionados com os grupos funcionais que complexam os metais possuem maior disponibilidade de ligações, esta disponibilidade provoca sua menor participação no caracter da complexação, ao contrário, os AF, que são moléculas de menor pesso molecular e mais solúveis, apresentaram maior tendência a complexação.Acredita-se que embora a evolução da pedo-paisagem não tenha relação direta com as características das substâncias húmicas e sim com a matéria orgânica total, nos horizontes dos solo foi verificada diferenças geoquímicas entre os ácidos fúlvicos e ácidos húmicos e estad diferenças acompanham os processos de alteração dos solos podzolizados e contribuem para o transporte da matéria orgânica em profundidade. Acredita-se que os ácidos húmicos possuem tanto cadeias de carbono aromáticas como com cadeias de carbono alifáticas na sua composição e ambas permanecem por mais tempo nos solos e precipitam-se em profundidade, nos ácidos fúlvicos as cadeias de carbono permanecem nos solos estão relacionados mais a aromaticidade, uma vez que esta substâncias são mais solúveis em meio ácido e possuem maior contribuição na alimentação das águas de drenagem.Conseguentemente a existências de cadeias de carbono influenciam na complexação dos metais o que permite levantar a hipótese de que os ácidos fúlvicos, principalmente, dos solos hidromórficos, que possuem um papel fundamental no desenvolvimento do meio ácido, e permitem assim, no avanço da podzolização e também o acúmulo do C em profundidade.Portanto, é possível verficar que existe um equilíbrio no sistema ambiental apresentado e que as matérias orgânicas, bem como os outros elementos do sistema, possuem participação nas transformações pedo-ambientais e estas transformações só continuarão ocorrendo atráves da preservação ambiental deste ambiente.

		Hidromórfico													
	2	Podzol	19-55	E1	5YR6/1	Anexos 71,2	0,2			2,9		25,7		96,9		Arenosa	0,05
		Hidromórfico													
		Podzol	55-97	E2	White page	65,7	1,65			2,6		30,1		95,8		Arenosa	0,02
		Hidromórfico			N 8.5/										
	Perfil	Solo Podzol	Profundidade 97+	Horizonte Bh	Cor 5YR3/2	Areia 61,1	Argila 7,9		Silte 3,5		Areia 27,5		Areia 88,6	Textura Arenosa	C (%) 2,6
		Hidromórfico			Munssell	grossa (%)	(%)		(%)		fina (%)	(%) grossa+ Areia Fina	(fração total)
		Podzol bem	0-3	A	5YR4/1	79,9	2,5			2,1		15,5		95,3		Arenosa	14,58
		drenado Criptopodzol	0-3	A	5YR3/1	65,1	6,3	4,0			24,6		89,7			Arenosa	12,51
		Podzol bem Criptopodzol	3-30 3-14	AE Bh3	5YR5/1 5YR5/1	79,0 69,0	3,2 4,1	1,7	0,20	25,2	17,6	94,2	96,6		Arenosa Arenosa	1,11 0,97
	3	drenado Criptopodzol	14-33	Bh2	5YR6/1	68,1	1,6	1,7			28,6		96,7			Arenosa	0,29
		Podzol bem drenado Criptopodzol	30-63 33-43	E1 Bhs	5YR7/1 5YR2.5/1	72,5 56,9	2,2 14,6	8,4		1,2	20,1	24,1	77,0	96,7	Arenosa Areia franca	0,40 12,40
	1	Podzol bem drenado Criptopodzol	63-150 43-52	E2 Cg1	5YR8/1 4 2.5YR6//4	66,6 61,3	1,2 11,5	12,0	5,1	15,2	27,1	76,5	93,7	Arenosa Areia franca	0,19 3,94
		Podzol bem Criptopodzol	120-150 52-80	EBh Cg2	10YR8/1 2.5y7/4	73,0 59,0	3,5 22,4	10,4	0,9	8,2	22,6	67,2	95,6	arenosa Franco arenosa	1,4 2,19
		drenado													
		Podzol bem	150+	Bh	5YR2.5/2	70,2	7,5			6,5		15,8		86,0		Areia-	6,7
		drenado Criptopodzol	100+	Cg3	2.5y8/2	40,8	34,1	17,9		7,2		48,0	Franca Franco argilo arenosa	1,15
		Podzol	0-3	A	5YR4/1	71,5	1,7			3,5		23,3		94,8		arenosa	9,87
		Hidromórfico													
		Podzol	3-19	AE	5YR5/2	79,7	1,8			0,8		17,6		97,4		Arenosa	0,77

Acknowledgements

The studies have been supported by FAPESP (process 2012/07600-0), by CNPq and CAPES-COFECUB Programs.

Acknowledgements:

This work was partly supported by the Professor Visitante Especial, Ciência sem Fronteira on Fluorescence Response on Heterogeneous Surfaces [processo N°313576/2013-0], CAPES/COFECUB (BEX-8033/14-5) and FAPESP (process 2012/07600-0) and by the International Humic Substance Society Grant 2017.

águas escuras e dinâmica das suas matérias orgânicas no decorrer desta evoluçãoNegro-AM", du cycle d'études supérieures en géographie de Universidade Estadual Paulista "Júlio

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soil horizons. On the other hand, this trend may reflect the inability of the organic matter to penetrate into the more clayey horizons because of the low porosity of the gleysol.

2.5.DISCUSSION

Drainage incision and new podzolization stage

The podzolization on clay-depleted soils (Acrisols) and the drainage incision that isolates the hilltop podzols and allows the spodic and saprolitic horizons to outcrop along the slope (BUENO; DO NASCIMENTO;[START_REF] Fritsch | From Plinthic Acrisols to Plinthosols and Gleysols: Iron and groundwater dynamics in the tertiary sediments of the upper Amazon basin[END_REF][START_REF] Fritsch | Deciphering the weathering processes using environmental mineralogy and geochemistry: Towards an integrated model of laterite and podzol genesis in the Upper Amazon Basin Crystal chemistry of Al and Fe Kaolinite Fe-oxides Organo-metallic complexes Laterit[END_REF] are the starting point for the evolution of the pedolandscapes of the studied catchment.

The soil description, texture analysis, and carbon distribution of the soil profiles and the spatial distribution of the soils in relation to the topography and vegetation indicate that there are two soil systems (podzolized and hydromorphic) located in different topographic positions and morphological segments of the slope. In figure 2.3a, the slight convexity that begins at a knickpoint in the slope announces the appearance of the hydromorphic podzol. Further downslope, this convexity becomes stronger and gradually transitions into a concave segment, after a straight transition segment. The first knickpoint in the slope reveals the erosive truncation of the thick podzol, while the second knickpoint exposes the erosive unconformity between the upslope segments and the downslope section of the slope and announces the lateral difference between the upslope and downslope soil profiles (thick and hydromorphic podzols). The presence of the second erosive unconformity is confirmed by the fact that the E2 and Bh horizons of the thick and hydromorphic podzols are discordant with the concave segment of the slope, i.e., they outcrop on the slope (Figure 2.3a).

Therefore, there is a clear difference in the evolution, over time, between the soils of the upslope and downslope sections.

In the downslope section of figure 2.3a, there is a global increase in the carbon content (Table 1) from the thick and hydromorphic podzols to the cryptopodzol, which is attributed to the Bh3 and Bh2 horizons of the cryptopodzol, and a decrease in carbon towards the base of the profile. This organic matter accumulation front also permeates the rock alteration horizons such as the CBhs horizon of the cryptopodzol. This distribution suggests a strong accumulation of organic matter throughout the downslope segment, preceded by the dissolution and mobilization of organic matter

Soil study and soils samples

The soils were studied based on a structural analysis approach [START_REF] Boulet | Analyse structurale et cartographie en pédologie 1 -Prise en compte de l'organisation bidimensionnelle de la couverture p8dologique μ les Etudes de toposéquences et leurs principaux apports A la connaissance des sols[END_REF] and classified according to FAO (2006). In the field, soil samples were collected from three pits, one by each profile, in November/December 2013. The samples were air dried in the laboratory, smashed, sieved at 2 mm, milled to 150 mesh and subdivided into aliquots for HS extraction and elemental analysis. In total, 18 soil samples were collected. The three profiles present the following successive pedogenic horizons: A11, A12, E12, E1, E2, EBh and Bh for P1; A, AE, E1, E2 and Bh for P2 and A11, A12, A/E, Bhs, Cg1, Cg2 and Cg3 for P3 (Figure 3.2). These soil horizon successions are typical of podzol soils (LUNDSTRÖM; [START_REF] Lundström | The podzolization process. A review[END_REF][START_REF] Lundström | The podzolization process. A review[END_REF].

The first quadrant (left quadrant north (N) has functional groups with wavenumber ranges of 2,940 -2,900 cm -1 (-CH aliphatic) and 3,440-3,100 cm -1 (-OH), and these vectors distance themselves from the central axis of the two dimensions. The left quadrant south (S) has the functional groups with wavenumbers of 1,590 cm -1 (C=C aromatic); 1,250 cm -1 (C-O ether/alcohol);1,050 cm -1 (C-O polysaccharide) and 1720 -1660 cm -1 (C=O carboxylic) associated with the E4/E6 ratio, the last distances from the central axis. In the left quadrant S are the functional groups in the bands 1590 cm -1 (C = C -aromatic); 1,250 cm -1 (C-O-ether / alcohol); 1,050 cm -1 (C-O-polysaccharide) and 1720-1660 cm -1 (C = O-carboxylic) and E4/E6, in which vectors also distance themselves from the central axis. The S right quadrant group is composed of the high E2/E3 and Silt/CoS ratios.

The functional groups (-CH aliphatic) and (-OH) have no direct relationship with the aromaticity (E2/E3) and horizon porosities, while they have an inverse relationship with the functional groups formed by (C=C aromatic), (C-O ether/alcohol), (C-O polysaccharide), (C=O carboxylic) and the condensation index, in the left quadrant S In turn, the latter functional groups maintains a positive relationship with the aromaticity (E2/E3) and porosity of the horizons. On the data projection, five groups have a good delimitation according to their similarities (Figure 10B). Out of these groups, 5 soil horizons remain; four are FA (E1P1, A/EP3, Cg2P3 and Cg3P3) and one is HA (Cg3P3). Two horizons are close to the groups: E1P1-FA close to group A and A/EP3-FA, close to group D. Cg3P3-AF is not too far from groups D and E. Cg2P3-AF is in the extreme SE