Soils represent an important terrestrial carbon (C) sink, storing up to three times the amount of atmospheric C, however climate and land use changes may transform soils into C sources. River corridor (RC) soils and associated C are at risk to become mobilized by erosion such as bank failure and scour events. Once soil-derived organic C is transferred into the stream, microbial processes and photodegradation of the dissolved, labile (or bioavailable) fractions can lead to the production of CO2, which can evade and increase atmospheric CO2 levels. Because predicted increases in heavy precipitation will likely increase this type of riverine erosion, it is important to better understand the potential for the release of bioavailable C from RCs. One objective of this thesis was therefore to identify and characterize representative samples of soils from a typical Vermont RC for common land covers and simulate the production of dissolved organic matter (DOM) during riverine soil erosion. Field sites representative of typical agricultural and forested land uses were selected based on the analysis of 106 existing samples and resampled multiple times over the summer of 2015. Production of DOM from riverine erosion was simulated using aqueous soil extracts (ASE), where soil and water were shaken at fixed ratios followed by the separation of the extract. To study the characteristics of these extracts (which serve as analogue of stream water after erosion), water extractable C (WEOC) concentrations, water extractable nitrogen, fluorescence properties of DOM, and bioavailability were determined. Results indicated a common, dominantly terrestrial source material for all land covers, but C concentrations and fluorescence properties differed. High but variable amounts of soil organic C and WEOC were observed in agricultural riparian and agricultural stream bank samples, and lower concentrations in agricultural field, forest, forest riparian, and forest stream banks. WEOC bioavailability was high in all agricultural land covers and low in forested land covers. Because this study is the first in which ASE are used as analogues for stream water after riverine erosion, a second objective was to test laboratory methods used in this study for their effect on WEOC, fluorescence properties, and bioavailability. Specifically, the effects of soil drying, soil storage, and the effects of the extraction solution were tested. For this, ASE were prepared from soils that were field moist, dried, and after two years of storage. In addition, dried soils were extracted using different solutions including a salt solution, river water, and double deionized (DDI) water. Results indicated WEOC concentration and microbial humic-like fluorescence from extracts of dried soils were higher than those in extracts of field moist soils, while WEOC concentration and microbial humic-like fluorescence was highest in extracts of soils stored long term. In addition, the bioavailability of WEOC was higher in dried soils than field moist soils. The extraction solutions of DDI water and river water produced DOM with similar fluorescence properties, while the salt solution extracted a different, less humified pool of C. Overall, the ASE methods used in this study are effective in simulating stream bank erosion and subsequent C release into stream water, however the effects of drying the soils need to be considered when assessing DOM.

Investigating linkages between the compositions of suspended (seston) and benthic particulate matter is important to the understanding of organic matter (OM) cycling and nutrient retention in aquatic systems. We compared the quantity and quality of the truly suspended (TS) and settleable (SB) fractions of seston as well as benthic particulate matter in the tidal freshwater James River, Virginia. The mass of seston and OM was consistently higher in the TS fraction compared to the SB fraction. OM was preferentially retained in the TS fraction relative to seston. The proportional contribution of OM constituents (chlorophyll a, particulate organic carbon and nitrogen) to the two fractions was consistent across observed concentrations whereas increases in seston concentration resulted in decreased proportions in the TS fraction. Benthic constituent reservoirs were large relative to the SB fraction but the higher proportion of OM in the SB fraction suggests that the settleable material was more labile.

Dans un contexte énergétique en crise, les sources alternatives d'énergie et d'économie d'énergie sont primordiales. Fort de ce constat, la station d'épuration de demain se doit d'atteindre un bilan énergétique positif. Dans cet objectif, de nombreux travaux de recherche se focalisent au niveau mondial sur la valorisation matière et énergétique à travers un procédé d'intérêt : la digestion anaérobie des boues. Afin d'optimiser ce procédé, la connaissance de la matière organique entrante est cruciale pour ne plus la subir mais la contrôler et en prédire les impacts sur les performances des digesteurs, notamment grâce à la modélisation. Une méthodologie de caractérisation de la matière organique des boues a donc été mise en place et testée afin de prédire les variables du modèle de digestion anaérobie basées sur la biodégradabilité et la bioaccessibilité. Cette méthode repose sur la mesure de la fluorescence en 3 dimensions réalisée sur les extractions chimiques de la boue, extractions simulant son accessibilité. Les résultats obtenus sur 52 échantillons de boues (primaires, secondaires, digérées, et traitées thermiquement) ont mis en évidence avec succès la corrélation entre cette méthode et la biodégradabilité anaérobie ainsi que la bioaccessibilité des boues. Le temps analytique classique de 30 jours pour les tests de potentiel méthane est par ailleurs réduit à 5 jours. Grâce à ces résultats, les variables d'entrée du modèle des processus biologiques ont pu être caractérisées ainsi que les composés réfractaires à la digestion. Une validation de la méthodologie a également été réalisée par le biais de la modélisation de 2 réacteurs pilotes expérimentaux. Une analyse de scenarios utilisant le modèle calibré a aussi montré que grâce à la prédiction de la bioaccessibilité et de la biodégradabilité, un temps de séjour minimum des digesteurs peut être calculé via une corrélation linéaire et ainsi optimiser le dimensionnement des digesteurs. De plus, cette approche s'est avérée être d'un grand potentiel en termes d'applications pour l'instrumentation et l'aide à la décision afin d'optimiser les performances des procédés de digestion anaérobie. / In an energetic crisis context, alternative sources of energy and saving costs has become of first importance. From this observation, the wastewater treatment plants of the future aim at a positive energetic balance and worldwide research on sludge treatment today focuses on energetic and material valorization through the optimization of anaerobic digestion processes. To this end, knowledge of the input organic matter is crucial to avoid suffering from these disturbances and to control, predict or drive the process through modeling. In the present study, a methodology of sludge characterization is investigated to describe biodegradability and bioaccessibility variables used in anaerobic digestion models. This method is based on the three dimensional fluorescence spectroscopy measurement performed on the chemical extraction of sludge simulating accessibility. Results obtained in 52 sludge samples (primary, secondary digested and thermally treated) show that the method can be successfully correlated with the sludge biodegradability and bioaccessibility within 5 days instead of the 30 days usually needed for the biochemical methane potential tests. Based on these results, input variables of dynamic models of biological processes occurring in anaerobic digestion have been characterized as well as recalcitrant fluorescent compounds. Validation has been performed with modeling of experimental data obtained from two different laboratory scale reactors. Scenarios analysis with the calibrated model have shown that using the measurements of sludge bioaccessibility and biodegradability, a minimal hydraulic retention time could be calculated with a linear correlation leading to the improvement of digesters design. Moreover, this approach has a high potential for applications such as instrumentation or decision support systems to improve both control and optimization of anaerobic digestion processes.

La culture du palmier à huile en milieu villageois prend de plus en plus d'ampleur dans les zones tropicales où elle contribue pour une part importante à l'économie des pays. Au Bénin, les palmeraies villageoises sont en forte expansion dans un climat particulier caractérisé par des déficits hydriques annuels élevés. Les caractéristiques assez particulières de ces palmeraies villageoises, comme l'association des cultures vivrières dans les jeunes palmeraies, l'absence de fertilisation minérale durant tout le cycle de culture et l'exportation de tout ou partie de la biomasse recyclable, nous interrogent sur la durabilité du système de production. L'étude a été conduite dans le département du Plateau au sud-est du Bénin (2°30 - 2°45 E et 6°35 - 7°45 N). Une première étape de diagnostic de typologie des palmeraies a permis de constater que les palmeraies villageoises appartiennent majoritairement à des petits producteurs dont les faibles moyens financiers ne permettent pas de planter de grandes superficies, ni d'appliquer une fertilisation minérale aux palmiers. Les antécédents culturaux sont pour la plupart des champs de cultures vivrières. Au jeune âge, les palmeraies sont associées à des cultures vivrières très variées. Les pratiques de restitution des sous produits de transformation, limitées à quelques grands producteurs et les modes de gestion des feuilles d'élagage, distinguent les palmeraies villageoises. La gestion des feuilles d'élagage commence à 7 ans d'âge des palmeraies et va d'une restitution quasi-totale en andain à une restitution nulle de ces feuilles au sol.Dans ce contexte, le mode de gestion des feuilles d'élagage dans les palmeraies villageoises peut induire des effets différents sur le système sol-plante, et son impact agronomique et environnemental mérite d'être exploré. A cet effet, la typologie des palmeraies a orienté le choix d'une chronoséquence de palmeraies représentant les deux modes contrastés de gestion des feuilles d'élagage : la restitution totale en andain (RT) et la restitution nulle (RN). Cette chronoséquence a servi aux études comparatives de l'effet de ces modes sur les compartiments sol et plante du système de production.Dans le compartiment sol, les stocks de matière organique, les paramètres physico-chimiques, l'activité microbienne et le statut de la matière organique ont été étudiés. Les études au niveau de la plante ont concerné dans un premier temps les paramètres de développement (densité, longueur et surface) des racines primaires, secondaires et fines. Et dans un second temps, les biomasses et minéralo-masses aériennes de la plante. Les études de biomasse aérienne ont nécessité la mise au point de méthodes non destructrices basées sur des équations allométriques d'estimations des biomasses de la feuille et du tronc. / Smallholder oil palm plantations are taking increasingly importance in tropical areas where the crop contributes significantly to the economy of the countries. In Benin, smallholder oil palm plantations are in expansion in a particular context characterized by high annual water deficits. Smallholder plantations are characterized in particular by the association of food crops with the young palms, the absence of mineral fertilization throughout the growing cycle and the removal of all or part of recyclable biomass. These specific characteristics raise some questions about the sustainability of the production system. The study was conducted in the region of Plateau located in southeast of Benin (2º 30-2º 45 E and 6 ° 35-7 ° 45 N). A first step diagnosis of the plantations' typology showed that small farmers own the major part of plantations. These small farmers have limited financial resources that neither allow them planting large areas nor applying mineral fertilizers. Food crops represent predominantly the previous cropping history of the plantations. The young palm trees are always associated with various food crops. Practices of mill residues recycling, limited to a few large producers, and the management of pruned fronds distinguish the smallholder plantations. Management of pruned fronds starts at 7 years old of the palm plantation. There are various ways of management of pruned fronds, from total recycling (RT) to no recycling at all (RN).In this context, the management of pruned oil palm fronds in smallholder plantations may induce different effects on the soil-plant system, and its agronomic and environmental impact deserves to be investigated. For this purpose, the typology of plantations allows to choose a chronosequence of palm plantations representing two contrasting ways of managing pruned fronds: RT of fronds piles and RN practices. This chronosequence was used to compare the effect of management of pruned fronds on soil and plant compartments.In the soil compartment, organic matter stocks, chemical parameters, microbial activity and status of organic matter were studied. The studies at the plant level concerned, first, the development parameters (density, length and surface area) of primary, secondary and thin roots; and second, the above ground biomass and mineral-mass of the plant. The studies of the aboveground biomass required to develop non-destructive methods based on allometric equations to estimate biomass of frond and trunk.On the agronomic view, the RT practice after 10 years of fronds recycling induced a significant effect on soil fertility parameters. Organic matter and nitrogen stocks at 0-50 cm depth increased by 70% and 50%, respectively, under frond piles compared to inter-rows without fronds. Surprisingly, the RN practice did not induce a decrease of organic matter stock over time. The increase of carbon and nitrogen stocks after 10 years of fronds recycling, improved soil parameters on the first 20 cm depth. The soil was enriched in organic matter (20gC.kg -1) and nitrogen (1.5gN.kg -1). The sum of exchangeable cations and cationic exchange capacity reached average values (7meq.100g -1) two times higher than the cases of no recycling of fronds. Calcium and magnesium contents increased while potassium contents are very low. The pH increased to 0.5 units and the soil shifted from acid to slightly acid status. Total recycling of fronds induced an increased soil microbial activity witch changed the quality of soil organic matter. So, the carbon content of fine organic fractions (< 20μm) increased to 40% at 0-5 cm and to 15% at 20-30 cm, compared to the no recycling of pruned fronds.

This research investigated the response of the dominant salt marsh macrophyte Spartina alterniflora var. Loisel to sedimentation from Hurricanes Gustav and Ike. A range of sedimentation was used to track the above and belowground plant response, as well as the volume of mineral and organic matter, in the upper reaches of the marsh soil from September 2008 to April 2009. Where storm sedimentation was greatest (~3.5 cm), there were significant increases in live aboveground biomass. Although live belowground biomass did not change significantly over time, the volumetric contribution of both mineral and soil organic matter in the shallow marsh soil increased. These results indicate that hurricane sedimentation may benefit subsiding coastal marshes by stimulating aboveground vegetation mass as well as soil organic matter volume. However, these results imply that there may be a sediment thickness threshold that must be met before such positive effects are expressed.

Dans cette thèse, deux axes ont été investigués. Le premier visait à étudier les relations Si-Corg et plus précisément Si-Clipides. La mise au point d’un protocole destiné à l’analyse des lipides associés aux frustules a été réalisée. Ce protocole nous a permis de montrer que ces lipides, représentant environ 1 % du Corg total, étaient dominés par des acides gras saturés (14:0, 16:0 et 18:0) chez Thalassiosira weissflogii. Le suivi de cette fraction au cours d’expériences de dégradation nous a permis de confirmer l’hypothèse de protection de la matière organique (MO) par la silice biogénique. Ces relations Si-Corg ont également été analysées après une croissance carencée en nitrate. Les résultats montrent que cette fraction n’était pas affectée par une carence en nitrate chez T. weissflogii.Notre deuxième axe d’investigation a consisté à étudier l’impact des conditions nutritives de croissance (carence en N, P et Si) sur la composition biochimique de T. weissflogii et sur sa biodégradation. Le calcul des constantes de dégradation de ses différents pools constitutifs (COP, NOP, monosaccharides et lipides) nous a permis de juger de l’efficacité des diatomées carencées, à exporter du Corg. La dégradation du Corg est peu affectée par ces carences à l’échelle globale mais sa quantité absolue par cellule augmente. De plus, la réponse physiologique de nos cellules face à une carence en Si semble être découplée du métabolisme énergétique contrairement aux réponses observées face aux carences en N et P. Cette variabilité de la réponse physiologique pourrait expliquer en partie la variabilité interbassins observée dans les corrélations entre flux de Si et de Corg en profondeur. / In this thesis, two axes of investigation on the diatom Thalassiosira weissflogii have been studied. The first one aimed to study Si-OC relationships and more specifically Si-OClipids. The development of an adapted protocol designed to analyse lipids intimately associated with frustules has been carried out. This protocol enabled us to show that lipids, amounting to about 1 % of the total OC, were dominated by saturated fatty acids (14:0, 16:0 and 18:0) in T. weissflogii cells. The monitoring of this fraction during degradation experiments enabled us to confirm the protective role of biogenic silica on organic matter (OM). These Si-OC relationships have also been analyzed after diatoms grew in nitrate starved conditions. Results indicated that this fraction was not impacted by nitrate starvation in T. weissflogii.Our second axis of investigation was to study the impact of nutrient growth conditions (starvations in N, P and Si) on T. weissflogii biochemical composition and its biodegradation. The estimation of degradation rate constants for some OM pools (POC, PON, monosaccharides and lipids) enabled us to assess the OM quality changes and the efficiency of nutrient starved diatoms to export OC. Interestingly, the degradation of OC is weakly affected by these starvations at the global scale (POC) but its absolute amount per cell increases. Moreover, the physiological response of cells facing Si starvation seems to be uncoupled with energetic metabolism, the opposite of observed responses during N and P starvations. This variability of the physiological response could explain partly the inter basin variability observed in Si and OC flux in depth.

Dans de nombreux gisements métalliques, notamment en contexte sédimentaire et en particulier dans le cas des shales noirs, des relations spatiales voire génétiques sont décrites entre la matière organique et les métaux. Une série de shales/schistes noirs affectés par des conditions thermo barométriques croissantes a été sélectionnée afin d'étudier le comportement et le devenir de l'uranium de la sédimentation au métamorphisme. Dans les Alum Shales cambro ordoviciens (Suède) faiblement enfouis, l'uranium reste dispersé et n'apparaît sous aucune forme minéralogique identifiable. Le passage des Alum Shales dans la fenêtre pétrolière et la génération d'hydrocarbures n'a pas provoqué de remobilisation identifiable de la concentration primaire, les hydrocarbures migrés ne transportant pas l'uranium. En revanche, le métamorphisme de faciès schiste vert associé à l'orogénèse calédonienne a entraîné une réexpression de la minéralisation uranifère sous la forme d'uraninite, d'urano titanates et/ou de phospho silicates à U, Ti, Zr, Y. Dans le cas des schistes noirs paléoprotérozoïques de Talvivaara (Finlande), le métamorphisme de faciès amphibolite a provoqué la remobilisation de l'uranium synsédimentaire et la cristallisation synmétamorphique, pendant l'orogénèse svécofennienne à 1880 1870 Ma, de cristaux d'uraninite fréquemment inclus dans des nodules carbonés. Cette étude montre que l'uranium, préconcentré au moment de la sédimentation, reste immobile pendant les premiers stades d'enfouissement mais est remobilisé dans les conditions P T croissantes et cristallise sous forme d'oxydes d'uranium pouvant évoluer vers des (phospho-)silicates d'uranium / In many metallic deposits, especially in sedimentary context and particularly in black shales, spatial or genetic relationships are described between organic matter and metals. Several black shales/schists affected by increasing thermo barometric conditions were selected to study the behavior and fate of uranium from sedimentation to high grade metamorphism. In shallow buried cambro ordovician Alum Shales (Sweden), uranium is dispersed and is not detectable as a particular mineralogical expression. Thermal maturation of the Alum Shales and hydrocarbon generation did not cause any identifiable remobilization of primary concentration, since migrated hydrocarbons did not carry uranium. In contrast, greenschist facies metamorphism associated with the Caledonian orogeny resulted in a re expression of uranium mineralization as uraninite or urano titanate crystals, which may evolve into U Ti Zr Y phospho silicates. In the case of Talvivaara, amphibolite facies metamorphism caused remobilization of synsedimentary uranium and synmetamorphic crystallization, during Svecofennian orogeny at 1880 1870 Ma, of uraninite crystals that are frequently included in carbonaceous nodules. This study shows that uranium, which is preconcentrated during sedimentation, remains immobile in the early stages of burial but is remobilized with increasing PT conditions and crystallizes as uranium oxides and/or uranium (phospho-)silicates

The dissolved air flotation (DAF) has been used in drinking water treatment for its excellent algae and natural organic matter (NOM) removal. DAF drinking water treatability test are often conducted in a DAF jar test apparatus. Although, DAF jar test studies showed that they were able to predict NOM removals at full-scale facilities well, they have not always been successful in predicting the turbidity removals. One possible reason of the DAF jar test inaccuracy results could be associated to the small jar diameter, which may create wall effects. Therefore, the first two objectives of this research are: a) to develop and test a new, larger diameter and larger volume batch bench-scale dissolved air flotation system (LB-DAF) to better simulate turbidity removals in drinking water applications; b) to confirm these results by comparing the LB-DAF and full-scale DAF turbidity removals for two other source waters. The raw water characteristics of the three plants were quite different and the testing was performed at different times of the year. The development/optimization of the LB-DAF evaluated the impact of different variables (i.e., mixing intensity, water depth/tank diameter ratio, impeller shape, saturator pressure and recycle ratio). The results showed that the LB-DAF predicted well the full-scale DAF turbidity removals at three water treatment plants, and these predictions were better than those of DAF jar tests. For the LB-DAF design and operational variables evaluated had a limited impact on the turbidity removals. The LB-DAF predicted well DAF full-scale turbidity removals regardless of water temperature. This is an indication of the robustness of the DAF system. Ballasted sedimentation (BS) is a compact coagulation/flocculation and sedimentation process combination that has become very popular because it is very compact and because it can handle large variations in raw water turbidity and NOM. The literature survey did not initially identify studies on the BS treatment of algal impacted waters, for which DAF is considered particularly suitable. Thus, the third main objective of this dissertation was to compare the efficiency of BS with that conventional gravity settling (CGS), and that of DAF for the treatment of an algal impacted water via jar tests. These comparisons were performed at the Belleville Water Treatment Plant using Bay of Quinte water, one of the most eutrophic zones of Lake Ontario. Unfortunately, a change of weather prior to the testing resulted in raw water samples with relatively low concentrations of algae and cyanobacteria. The testing showed that DAF and BS had very similar NOM, cyanobacteria/algae (chlorophyll a and phycocyanin) removals.; however, the BS required microsand addition, polymer addition and a slightly higher alum dose. Only for turbidity removal the DAF was somewhat superior. It is suggested that these comparison experiments be repeated with waters that are more impacted by algae and cyanobacteria.

A produção de lodo de esgoto vem aumentando a cada dia nas estações de tratamento, e a sua disposição final é um problema a ser resolvido. Uma das alternativas encontradas para a disposição final desses resíduos com benefícios ambientais e principalmente econômicos é a reciclagem agrícola, devido a sua composição em termos de matéria orgânica e nutrientes para as plantas. O objetivo deste trabalho foi avaliar os efeitos da adição do lodo de esgoto na matéria orgânica do solo, em um experimento de curto período de duração. As amostras utilizadas neste experimento foram coletadas na Fazenda Retiro, município de Monte Azul Paulista/SP, em áreas com cultivo de citros. O experimento foi composto de 5 tratamentos, uma testemunha e 4 doses de logo de esgoto. Além dos 5 tratamentos também foram amostrados o solo de mata (referência) e lodo de esgoto. Dessas amostras foram extraídos os ácidos húmicos (AH). Foram avaliadas as alterações ocorridas nas estruturas dos AH quanto aos teores de carbono, composição de grupos funcionais, número de radicais livres do tipo semiquinona e grau de humificação. O solo in natura também foi avaliado quanto aos teores de carbono e grau de humificação da matéria orgânica (MO). Para isso, foram utilizadas técnicas como análise elementar, TOC e espectroscopia de EPR, 13C RMN, FTIR, UV-Vis, Fluorescência e FIL. Através dos resultados de análise elementar, foi possível notar que não houve alterações na estrutura dos AH após a adição de lodo de esgoto, podendo ser comprovado através dos espectros de FTIR e 13C RMN, onde não foram observadas diferenças significativas para os diferentes tratamentos. A adição de lodo de esgoto em solos sob cultivo agrícola, entretanto, incorporou MO fresca, pois quando se compara o solo testemunha e o solo que recebeu a dose mais alta de lodo observa-se um aumento de 75% no carbono orgânico do solo. O AH do lodo de esgoto possui um caráter bastante alifático e em sua estrutura uma considerável quantidade de radicais livres do tipo semiquinona. Ao ser adicionado ao solo, observa-se que modifica a concentração do número de radicais livres do tipo semiquinona sem alterar os grupos funcionais do AH do solo. Portanto, no sistema estudado, a adição de lodo de esgoto mostra que o número de radicais livres do tipo semiquinona presentes no solo não é proporcional ao grau de humificação da MO do solo. Os resultados demonstraram que a espectroscopia de fluorescência tanto em solução como a Induzida por Laser forneceu dados coerentes à cerca do grau de humificação da MO. Foi possível observar uma diminuição no grau de humificação no solos submetidos à adição de lodo de esgoto, aproximando-se do solo de mata utilizado como referência. A concentração de carbono no solo aumentou, mesmo depois de ter sido interrompida a aplicação por 2 anos, e o grau de humificação da MO diminuiu, sendo menor ainda do que o solo de mata utilizado com referência. Portanto, podemos considerar este tipo de manejo onde se utiliza lodo de esgoto para condicionamento do solo apropriado tanto do ponto de vista ambiental quanto do ponto de vista agronômico. / The production of sewage sludge increases daily in treatment stations and definitive disposal is a problem to be resolved. One of the alternatives found to dispose such residues, with environmental and economic benefits, is agricultural recycling, owing to its organic composition and plant nutrients. The objective of the present work was to asses the effects of waste sludge addition to soil organic matter in an experiment of short duration. The samples used in this experiment were collected from Fazenda Retiro, a municipality of Monte Azul Paulista/SP, in an area that has citrus plantations. The experiment was composed of 5 treatments, reference soil and 4 sewage sludge doses. In addition to the 5 treatments, the forest soil (reference) and sewage sludge were also sampled. From these samples humic acids (HA) were extracted. The alterations that occurred in the HA structures were assessed regarding ratios of carbon, composition of functional groups, number of semiquinone-type free radicals and rate of humification. In natura soil was also assessed regarding carbon ratio and rate of humification of organic material (OM). Thus, techniques as elementary analysis, TOC and EPR spectroscopy, 13C RMN, FTIR, UV-Vis, Fluorescence and FIL were used. By means of elementary analysis results, it was possible to notice that there was no alteration in the HA structure after addition of sewage sludge, therefore, verifying through FTIR and 13C RMN spectra no significant differences observed for the different treatments. However, addition of sewage sludge in agricultural cultivated soils incorporated fresh OM, since when comparing the reference soil and the soil that received the highest dose of sludge, an increase of 75% is observed in the organic carbon of the soil. The HA of the sewage sludge has a very aliphatic characteristic and in its structure, a considerable quantity of semiquinone-type free radicals. It is observed that when added to the soil, it modifies the concentration of the number of semiquinone-type free radicals, without altering the HA functional groups of the soil. Therefore, in the studied system, addition of sewage sludge demonstrates that the number of semiquinone-type free radicals found in the soil is not proportional to the rate of OM humification of the soil. The results demonstrated that fluorescence spectroscopy in solution, as well as Laser-Induced fluorescence of whole soil, provided coherent data concerning the rate of OM humification. It was possible to observe reduction in the rate of humification in soils submitted to sewage sludge, in close approximation to the forest soil used as reference. The carbon concentration in the soil increased, even after interrupting application for 2 years, and humification degree of OM diminished, proving to be less than the forest soil used as reference. Thus, we can consider this type of management, when sewage sludge is used to condition soil, as appropriate from an environmental point of view, as well as from an agronomical one.

Os sedimentos costeiros são importantes globalmente, pois atuam como receptores de grandes quantidades de material orgânico alóctone e autóctone, sendo responsáveis por cerca de 90% do enterramento de carbono no oceano global. Dentro dos ecossistemas de plataforma continental, a fauna bêntica desempenha papel vital tanto como receptora de energia proveniente do pelagial, quanto como fornecedora de energia para os organismos demersais e de nutrientes para o fitoplâncton. O objetivo principal do presente trabalho foi investigar a variação temporal da dinâmica da macrofauna bêntica na plataforma interna de Ubatuba. A dinâmica bêntica foi analisada pela abundância, biomassa, descritores da comunidade (riqueza, diversidade, equitatividade) e análise trófica dos grupos mais abundantes, em função da origem e composição da matéria orgânica sedimentar. As coletas foram realizadas mensalmente em uma estação fixa, com início em outubro de 2006, por um período de um ano. A estação fixa possui uma profundidade de 40 m e um regime oceanográfico de transição entre águas costeiras e de plataforma continental. A composição da matéria orgânica em termos de MOT, fitopigmentos, fitodetritos e biomarcadores lipídicos apresentou uma complexidade típica de ambientes de plataforma interna, relacionados à dinâmica oceanográfica que rege os principais eventos de acúmulo ou remoção da matéria orgânica lábil na região de Ubatuba. A composição dos biomarcadores lipídicos presentes no sedimento evidenciou que a matéria orgânica particulada na região de plataforma interna de Ubatuba possui uma origem principalmente autóctone, e que está constituída por uma combinação de material derivado do plâncton vivo ou detrítico, da produção bacteriana e da fauna associada ao sedimento, havendo uma contribuição terrestre relativamente pequena. O presente estudo indicou que a dinâmica bêntica na região da plataforma interna de Ubatuba é moldada por forçantes ambientais, como a intrusão de massas dágua (e.g. ACAS) trazendo nutrientes para a zona fótica e estimulando a produção primária fitoplanctônica nova, induzindo o aumento na densidade e biomassa bêntica. A chegada de frentes frias, com ventos fortes, mistura da coluna dágua e revolvimento do fundo também possui fundamental importância, através do decréscimo nos valores dos parâmetros da comunidade bêntica. Esse padrão de acúmulo e remoção sugere que a biota bêntica da plataforma interna de Ubatuba esteja numa constante dinâmica de colonização e recolonização, que pode ser chave na manutenção de altos níveis de riqueza e equitatividade na região. Os resultados obtidos no presente estudo sugerem um íntimo e complexo acoplamento bentopelágico dependente, por um lado, de eventos oceanográficos de mesoescala (i.e. centenas de km; intrusão da ACAS) e, por outro, de eventos atmosféricos que influenciam o sistema bêntico em escala local, através da ressuspensão de sedimentos. / Coastal sediments are globally important for their role in the carbon cycle, being responsible for about 90% of the carbon burial in the global ocean. In continental shelf ecosystems, benthic communities play a vital role receiving energy from the pelagic system, serving as food source for demersal organisms, recycling nutrients back to the water column and sequestering part of the carbon into deeper layers of marine sediments. The present study aimed to investigate the variation on the dynamics of the benthic macrofauna on the inner shelf off Ubatuba-SP. Benthic macrofauna abundance, biomass, species richness, diversity, equitability and polychaete trophic groups were compared with the origin and composition of sedimentary organic matter. Sampling was carried out on a monthly basis starting in October 2006 for a year in a permanent station at 40 meters depth. The area is characterized by a transition between coastal and oceanic regimens. Sedimentary organic matter composition in terms of total organic matter, lipid biomarkers and phytopigments and phytodetritus showed a complexity typical from inner shelves and was driven by oceanic and atmospheric dynamics. Lipid biomarker composition revealed that particulated organic matter was mainly derived from autochthonous sources, composed of a combination of material derived from live plankton and detritic remains, bacterial production and from the benthic metazoan fauna. Terrestrial contribution to the sediment organic matter was small. The present study indicated that the benthic dynamics in the inner shelf off Ubatuba is molded by environmental forcing, especially the intrusion of water masses onto the shelf (e.g. ACAS), which brings nutrients to the euphotic zone stimulating new phytoplanktonic primary production. This enhances the flux of organic matter to the bottom increasing the benthic biota density and biomass. The arrival of cold fronts, with strong S-SW winds promoting water column mixing and sediment resuspension, was also fundamental in decreasing benthic community parameters (i.e. abundance and biomass). The dynamics of organic matter accumulation and removal suggest that the benthic biota in the inner shelf of Ubatuba is subjected to a constant pattern of settling and recolonization, which can be a key factor in the maintenance of high levels of species richness and equitability. The results obtained in the present study suggest a strong and complex benthic-pelagic coupling, influenced by mesoescale oceanographic events (i.e. hundreds of km; intrusion of ACAS) on the one hand and, on the other, by atmospheric events influencing the benthic system on a local scale, through the remobilization of sediments.