O presente trabalho avaliou a variabilidade espacial e temporal de ácidos húmicos (HA) e proteínas (PROT), em uma grande lagoa rasa subtropical. Para tanto, foi usado Cromatógrafo Líquido de Alta Eficiência por Exclusão de Tamanho (HPLC-SEC). Foram incluídas como variáveis explanatórias, carbono orgânico dissolvido (COD), nitrogênio total (NT), nitrogênio total dissolvido (NTD), cor, pH e temperatura. A área de estudo foi a Lagoa Mangueira, uma grande lagoa rasa oligo-mesotrófica inserida ao Sistema Hidrológico do Taim – SHT. As amostras foram coletadas em quatro campanhas, durante o ano de 2010, em dezenove pontos diferentes, compreendendo as zonas litorâneas e pelágica, localizadas no sul, centro e norte da lagoa. Resultados indicaram que a Lagoa Mangueira apresenta heterogeneidade temporal interanual em relação a estas variáveis, ao mesmo tempo que possui um perfil longitudinal homogêneo, não evidenciando um arranjo espacial definido. / The present work evaluated spatial and temporal variability of humic acids (HA) and proteins (PROT) in a large subtropical shallow lake. For this purpose, High Performance Liquid Chromatograph by Size Exclusion (HPLC-SEC) was used. Dissolved organic carbon (DOC), total nitrogen (TN), total dissolved nitrogen (TDN), color, pH and temperature were included as explanatory variables. The study area was Mangueira lake, a large shallow oligo-mesotrophic lake located into the Taim Hydrological System. The samples were collected in four samplings during the year 2010 at nineteen different points, including the littoral and pelagic zones, located in the south, center and north of the lake. Results showed that the Mangueira lake presents interannual temporal heterogeneity in relation to these variables, at the same time that it has a homogeneous longitudinal profile, not evidencing a defined spatial arrangement.

Matéria orgânica natural (MON) é uma complexa matriz de compostos orgânicos originados de fontes naturais que estão presentes nas bacias hidrográficas e dentro dos corpos hídricos. MON é comprovado precursor de subprodutos da desinfecção (SPD), além de afetar processos de tratamento de água tais como coagulação, desinfecção, oxidação, adsorção em carvão ativado e filtração em membranas. Por estas razões, a redução da MON no tratamento de água para consumo humano é importante. Muitos métodos têm sido utilizados para caracterizar e quantificar a MON. Entre os métodos usados se encontram a adsorção em resinas e parâmetros de massa. Carbono orgânico total (COT), carbono orgânico dissolvido (COD), absorção à luz ultravioleta (UV254) e absorbância específica de luz ultravioleta (AEUV) são usualmente utilizados como parâmetros de massa. O fracionamento rápido é uma técnica que usa diferentes resinas para separar frações da MON. Nesse contexto, este trabalho teve como objetivo geral caracterizar a matéria orgânica dissolvida usando o método do fracionamento rápido e os parâmetros COD, UV254 e AEUV em processos de tratamento de água para consumo humano. Também foram analisados turbidez, cor, pH e alcalinidade. Foram avaliados os efeitos dos processos de coagulação, sedimentação, filtração em filtro de areia e adsorção em carvão ativado granular (CAG) nas frações que formam a MON. As amostras de água foram coletadas em estação de tratamento de água da cidade de Porto Alegre, RS. Os valores de turbidez, cor, pH, alcalinidade, UV254 e COD reduziram-se ao longo dos processos de tratamento, enquanto que a AEUV aumentou na sequência dos processos. Os valores de absorção de UV254 decresceram à medida que as amostras passavam através das distintas resinas do fracionamento rápido (DAX-8, XAD-4 e IRA-958). Estas frações tiveram reduções importantes em todas as amostras. Os AMH decresceram de 2,29 mg/L COD na água bruta para 0,25 mg/L COD no efluente da coluna de carvão ativado, enquanto que os ALH reduziram de 1,29 mg/L na água bruta para 0,22 mg/L no efluente do filtro de CAG. As concentrações observadas de matérias hidrofílicas carregadas (MHC) (ex., proteínas) e hidrofílicas neutras (MHN) (ex., carboidratos) foram próximas a zero em todas as amostras. Foi possível concluir que os processos de tratamento afetam a distribuição de frações da MON presente na água. / Natural organic matter (NOM) is a complex matrix of organic compounds originated from natural sources that are present in the watershed and in within water bodies. NOM is a known precursor of disinfection byproducts (DBP) and affects drinking water treatment processes such as coagulation, disinfection, oxidation, carbon adsorption and membrane filtration. For these reasons, the reduction of NOM in water treatment is important. Many methods have been used to characterize and quantify NOM, among them, the resin adsorption and the mass parameters methods. The latter include total organic carbon (TOC), dissolved organic carbon (DOC), ultraviolet absorption at 254 nm (UV254), and specific UV absorption (SUVA). Rapid fractionation is one of the resin adsorption methods. This study has as objective the characterization of dissolved organic matter using rapid fractionation and the parameters DOC, UV254 and SUVA in drinking water treatment processes. Turbidity, color, pH and alkalinity were also analyzed. It was evaluated the effect of coagulation, sedimentation, filtration in sand filter and granular activated carbon (GAC) adsorption in the fractions that form NOM. Samples were collected in a drinking water treatment plant in the city of Porto Alegre, RS. Values of turbidity, color, pH, alkalinity, UV254 and DOC decreased along treatment, while values of SUVA increased. UV254 reduced as the samples passed through the distinct resins used for rapid fractionation (DAX-8, XAD-4 e IRA-958). The main fraction of DOC in samples was very hydrophobic acids (VHA) (as humic acids) followed by slightly hydrophobic acids (SHA) (as fulvic acids). These fractions had major reductions as the samples run through the resins. VHA decreased from 2,29 mg/L COD in raw water to 0,25 mg/L COD in activated carbon column effluent, while SHA decreased from 1,29 mg/L in raw water to 0,22 mg/L in GAC filter effluent. Charged hydrophilic matters (CHA) (as proteins) and hydrophilic neutral (NEU) (as carbohydrates) were observed at concentrations next to zero in most samples. It was possible to conclude that drinking water treatment processes affect the fraction distribution of NOM in water.

The Belgian Coastal Zone (BCZ) in the Southern Bight of the North Sea is a highly dynamic and optically complex area. This is due to high non-algal particles (NAP) and coloured dissolved organic matter (CDOM) content which in spring adds together with undesirable blooms of the haptophyte Phaeocystis globosa. There is a need for improving the algorithms for chlorophyll a (chl a) retrieval in these highly turbid waters and for developing algorithms for species detection in order to attempt to create an early warning bloom system. This information will contribute to the knowledge of the extent and magnitude of the P. globosa bloom in Belgian waters. In this study, pure cultures of the main taxa present in the BCZ, diatoms and P. globosa, were combined with field measurements of light absorption of total particles, phytoplankton and dissolved material, pigment determination and phytoplankton counts to address the main objectives. Sampling was performed during 8 cruises covering winter, spring, summer and late summer, and along nearshore-offshore gradients from 2003 to 2006. <p>The area is characterised by a high spatio-temporal variability of IOPs due to the high dynamics of the area in terms of currents, salinity gradients and biological production. During spring the presence of P. globosa modulates the IOPs across all the area, the particle absorption is significantly higher than summer and there is no significant coast-offshore variability for phytoplankton and CDOM. <p>The design of chl a retrieval algorithms assumes negligible absorption of NAP and CDOM in the near infrared (NIR) and the use of a fixed value of specific phytoplankton absorption. It is shown that neglecting the NAP and CDOM absorption in the NIR will have a significant overestimation impact in retrieval of chl a. On the other hand, the specific phytoplankton absorption was found to be highly variable (0.015 „b 0.011 m2 mg chl a-1). Both results will affect directly the retrieved chl a. The spatial variability of CDOM was significant varying between 0.20-1.31 m-1 in the marine area and between 1.81-4.29 m-1 in the Scheldt estuary. CDOM was found to be related to salinity with conservative mixing within the Scheldt estuary and during some seasons in the BCZ, however deviations from conservative mixing suggest other inputs to the CDOM pool. Analyses of the spectral slope of the CDOM absorption curve revealed two main CDOM pools in the area, an allochthonous one delivered by the Scheldt estuary and an autochthonous one associated with the phytoplankton spring bloom decomposition. Algorithms for CDOM retrieval will be affected if the variability in the relation between CDOM and salinity is not taken into account. <p>The optical characterisation of diatoms and P. globosa from the BCZ in pure cultures revealed that the main differences in the phytoplankton absorption spectra were found at 467 and 500 nm corresponding to the absorption of the pigments chlorophyll c3 (chl c3) characteristic of P. globosa and fucoxanthin, respectively. Accordingly, both the absorption at 467 nm and the ratio 500/467 nm were successfully used to discriminate the two taxa in cultures and field samples. This latter indicator was not preserved in the reflectance signal due to degradation of the signal when passing from absorption to reflectance, and thus could not be used for algorithm development. The spectral feature at 467 nm was later used as the basis for the development of a flag-type algorithm to detect chl c3 using either absorption or water-leaving reflectance data. Also, the correlation between the algorithm¡¦s retrieved chl c3 and P. globosa cell number allowed the quantification of the bloom. The main findings of this thesis highlight the importance of the IOPs characterisation for the improvement and development of ocean colour retrieval algorithms in these highly complex waters.<p> / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

Dans les systèmes fluviaux-estuariens soumis à de fortes pressions agricoles, la matière organique dissoute (MOD) présente une origine liée essentiellement à l’amendement des sols. Cependant, il existe un manque d’information concernant la composition, le rôle et le devenir de cette MOD. L’objectif de cette thèse est d’apporter des éléments nouveaux sur l’identification des sources et du comportement de la MOD de façon globale et sélective dans des systèmes fluviaux-estuariens soumis à des impacts agricoles. L'analyse de la MOD a été réalisée à l'aide de 2 techniques analytiques récentes et originales: (i) une méthode électrochimique (DP-CSV), pour caractériser simultanément la glutathione (GSH-like), le thioacétamide (TA-like), et les acides fulviques (FA-like), (ii) une chromatographie liquide d’exclusion stérique couplée aux détecteurs de carbone, azote et UV (LC-OCD-OND-UVD), séparant la MOD en 6 fractions de taille et de nature différentes. Par rapport au système de référence, nos résultats ont montré des teneurs en composés organiques 1,5 à 4 fois plus fortes dans les systèmes agricoles. Ces anomalies sont liées à la pression agricole et au type d’élevage. Ces travaux ont aussi montré des variations saisonnières contrôlées par différents processus: un lessivage des sols en période de fortes précipitations pour les FA-like représentant la fraction majoritaire de la MOD, une purge des horizons profonds par la remontée des nappes phréatiques pour les TA-like et un apport à la fois terrestre et aquatique pour les GSH-like. Le long du gradient salé, les GSH-like et FA-like ont un comportement conservatif alors que d’importantes pertes ont été observées pour les TA-like. / In watersheds under strong agricultural pressure, manuring activities, particularly animal farming, are the main source of dissolved organic matter (DOM). However, the composition, the role and the fate of this DOM have been poorly studied. This study focuses on the sources, dynamics and transformation of the DOM and its constituents in riverine and estuarine systems affected by different agricultural practices. The analysis of DOM was performed using two recent and innovative analytical techniques: (i) an electrochemical method (DP-CSV), allowed us to characterize simultaneously three dissolved organic compounds: glutathione (GSH-like), thioacetamide (TA-like), and fulvic acids (FA-like), (ii) a size exclusion liquid chromatography coupled to an carbon, nitrogen and UV detector (LC-OCD-OND-UVD) allowed the DOM pool to be subdivided into 6 major sub-fractions. Relative to the pristine river, concentrations of organic compounds were found to be 1.5 to 4 times higher in impacted systems. These anomalies are related to the agricultural pressure and also to the type of livestock. Our results also showed that the seasonal variations were controlled by different processes: soil washing-out during high precipitation events for FA-like compounds which represent the major part of DOM, formation in deep horizons then rising of groundwater for TA-like compounds and a pedogenic and aquatic origin for GSH-like compounds. Along the salinity gradient, GSH-like and FA-like displayed a conservative behaviour whereas TA-like do not behave conservatively with important removals.

Suite à une anthropisation généralisée des ressources aquatiques et des écosystèmes associés, on retrouve de nombreux contaminants chimiques organiques à l’état de traces dans l’environnement aquatique. En parallèle de ces contaminants, dans les milieux aquatiques on retrouve également des molécules rassemblées sous la dénomination « matière organique dissoute (MOD) », qui sont des mélanges complexes de molécules et macromolécules, qui peuvent s’associer à ces contaminants et influencer leur comportement et leur distribution. Les interactions entre MOD et contaminants peuvent s’avérer difficiles à étudier étant donné qu’elles sont dépendantes de nombreux facteurs tels que la nature des contaminants et de la MOD, ainsi que des paramètres physico-chimiques du milieu. L’objectif de ces travaux était donc d’étudier ces interactions. Les contaminants organiques choisis ont été les Hydrocarbures Aromatiques Polycycliques (HAP) et les substances pharmaceutiques. D’autre part, plusieurs types de MOD d’origine naturelle ou commerciale ont été utilisés. Pour étudier les interactions, plusieurs techniques analytiques ont été développées dont la micro-extraction sur phase solide couplée à la chromatographie en phase gazeuse et à la spectrométrie de masse et l’extinction de fluorescence. / In relation with a widespread human impact on aquatic resources and ecosystems, many organic chemical contaminants are present at trace levels in aquatic environments. In parallel to these contaminants, dissolved organic matter (DOM), which is composed of complex mixtures of molecules and macromolecules, is also found and could be associated with these contaminants and influence their behavior and distribution. Interactions between DOM and contaminants can be very difficult to understand because they depend on many factors such as the nature of contaminants and DOM, as well as on environmental physico-chemical parameters. The aim of this work was thus to study these interactions. Organic contaminants studied were Polycyclic Aromatic Hydrocarbons (PAHs) and pharmaceuticals. On the other hand, several types of natural and commercial DOM have been used. To study the interactions, several analytical techniques have been developed like solid phase microextraction coupled to gas chromatography and mass spectrometry and fluorescence quenching.

De nombreuses friches héritées d’activités industrielles révolues présentent des pollutions organiques persistantes (charbon, goudron…). Alors que la réglementation impose un une évaluation du degré de contamination de ces sites, elle ne prend pas en compte les sous-produits de transformation tels que les composés polaires, peu considérés. Pourtant ils se solubilisent dans la phase aqueuse par percolation des eaux météoriques à travers ces surfaces contaminées. Bien que la littérature ciblant la matière organique dissoute (MOD) d’origine naturelle soit abondante, elle n’est pas directement transposable à la MOD issues des friches contaminées, qui reste à définir pour une meilleure compréhension du devenir de la pollution dans ces sites anthropisés. Une approche multi-techniques a été appliquée pour appréhender le plus précisément possible la MOD issue de terres d’anciennes cokeries et usines à gaz, par le biais d’expériences en laboratoire et des dispositifs de terrain (lysimètres). L’étude de ces derniers montre qu’ils contiennent une forte teneur en MOD aromatique, dont les composés aromatiques polycycliques ne représentent qu’une faible proportion de la MOD totale. Des expériences complémentaires ciblant l’influence de certains paramètres (pH et hydrophobicité) suggèrent un lien fort entre le pH et l’organisation spatiale de la MOD, ainsi qu’une diminution de la masse moléculaire apparente avec l’augmentation de l’hydrophobicité. Des expériences de vieillissement artificiel ont montré un enrichissement en produits polaires condensés entraînant leur forte mobilisation par l’eau / A large amount of wastelands inherited from former industrial activities contains persistent organic contamination (coal, coal tar…). While the regulation requires an evaluation of the contamination degree of these soils, it doesn’t take into account the transformation by-products such as polar compounds, poorly studied. Yet they solubilize in aqueous phase by percolation of meteoric waters through these contaminated sites. Despite the fact that literature targeting the fresh DOM is abundant, it is not directly transposable to the anthropogenic DOM coming from wastelands, which still need to be more precisely defined to improve our knowledge of this specific DOM and its evolution over time. A multi-technical approach was developed to comprehend the anthropogenic DOM coming from former coking and gas plant soils, thanks to a combination of laboratory experiments (under controlled conditions) and on field devices (lysimeters). Their study show that they contained high polycyclic aromatic compound (PAC) contents, whose proportions in polar PACs exceed the ones in soil measurements. However, these PACs only consist of a low proportion of the total DOM. Complementary experiences targeting the influence of some parameters (pH, hydrophobicity) show a major hydrophobic characteristic and suggest a strong link between the pH and the spatial DOM organization. Artificial aging experiences show an enrichment in polar compounds leading to their water mobilization

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Les petits plans d'eau, en particulier ceux riches en matière organique, sont encore négligés en tant que sources naturelles majeures d'émission de carbone (C) dans l'atmosphère et contributeurs importants au bilan mondial de C. Les mares de tourbières riches en matières organiques sont une source nette de C atmosphérique dans les écosystèmes de tourbières, qui sont généralement un puits net de C. Ces mares émettent des gaz à effet de serre (GES) à des taux plus élevés, en particulier de méthane (CH4), par rapport à d'autres petits plans d'eau lentiques (petits lacs et étangs), ce qui peut être attribué à la connectivité hydraulique des bassins donc aux apports en C de la tourbe environnante et aux caractéristiques morphologiques des mares. Cependant, il existe très peu d'informations sur les schémas et les mécanismes de la dynamique du C dans les bassins de tourbières par rapport à leur couvert végétal ainsi qu'à d'autres petits environnements aquatiques. En particulier, la matière organique dissoute (MOD), un important intermédiaire et substrat de C, peut influencer la dynamique des émissions de GES, mais son rôle demeure méconnu à l'échelle intra- et inter-régionale. Dans cette étude, nous avons caractérisé et identifié les patrons intra- et interrégionaux et les mécanismes potentiels contrôlant la quantité et la qualité de la MOD et des concentrations de GES, ainsi que leurs liens en analysant une gamme de variables optiques et chimiques et en compilant les données géographiques (c'est-à-dire le climat, le couvert végétal et morphométrie des bassins) à partir de bassins de tourbières ombrotrophes dans cinq régions de l'est du Canada (Grande plée Bleue, sud du Québec et région de la Minganie, est du Québec) et du sud de la Patagonie chilienne (Punta Arenas, parc Karukinka et île Navarino). Nous avons également effectué un échantillonnage interannuel dans la Grande plée Bleue pour identifier les tendances temporelles des concentrations et de la composition des GES et de MOD. Nous avons trouvé une variabilité interrégionale élevée dans les patrons de MOD et de GES par rapport à la variabilité intrarégionale qui était cohérente avec l'hétérogénéité des propriétés géographiques, en particulier, le climat. Les patrons interrégionaux des concentrations de GES étaient de plus déterminés par la couverture végétale environnante, la morphométrie du bassin et la composition de la MOD de type protéique. D'autre part, bien que nous n'ayons pas observé de patrons temporels significatifs dans les concentrations de GES, de MOD et de la composition de type humique terrestre au cours de l’été dans la Grande plée Bleue, les patrons temporels de GES ont été influencés par la concentration de MOD, la composition de type humique terrestre, et la chimie interne de l'eau. Dans l'ensemble, nos résultats suggèrent que les patrons interrégionaux de la MOD et des GES, et les liens entre eux, sont principalement contrôlés par le climat (température et précipitations), la couverture végétale et la morphométrie des bassins, tandis que les patrons temporels de la MOD et des GES sont principalement régis par des facteurs à l'échelle locale tels que la morphométrie des bassins et la connectivité hydrologique. / Small waterbodies, especially organic-rich, are still overlooked as a major natural source of carbon (C) emission to the atmosphere and an important contributor in the global C budget. Organic-rich peatland pools are generally net atmospheric C sources embedded in peatland ecosystems, which are generally net C sinks. They emit high areal rates of greenhouse gases (GHG), particularly methane (CH4), compared to other small lentic waterbodies (small lakes and ponds) which may be attributed to peat-pool hydraulic connectivity leading to C loading from the surrounding peat and morphological characteristics. But there is very little information on the patterns and drivers of C dynamics within peatland pools compared to their vegetated areas as well as other small aquatic environments. In particular, the role that dissolved organic matter (DOM), an important intermediate and C substrate, may play in GHG dynamics is poorly known at the intra- and inter-regional scales. In this study, we characterized and identified the intra- and inter regional patterns and drivers of DOM quantity and quality and GHG concentrations as well as their links. We did so by analyzing a range of optical and chemical variables and compiling geographic data (i.e., climate, vegetation cover and pool morphometry) from ombrotrophic peatland pools across five regions in eastern Canada (Grande plée Bleue, southern Québec and Minganie region, eastern Québec) and southern Chilean Patagonia (Punta Arenas, Karukinka Park and Navarino Island). We also conducted inter-annual sampling in Grande plée Bleue to identify the temporal patterns in GHG and DOM concentrations and composition. We found high inter-regional variability in DOM and GHG patterns compared to intra-regional variability which was coherent with the heterogeneity of geographical properties. Inter-regional patterns in GHG concentrations were driven by surrounding vegetation cover, pool morphometry and protein-like DOM composition. On the other hand, although we did not observe significant temporal patterns in GHG and DOM concentrations and terrestrial humic-like composition throughout the growing seasons in Grande plée Bleue, temporal patterns of GHG were influenced by the DOM concentration, terrestrial humic-like composition, and internal water chemistry. Overall, our results suggest that inter-regional patterns in DOM and GHG, and the links among them are predominantly controlled by the broad-scale patterns in climate (temperature and precipitation), vegetation cover, and pool morphometry, while temporal patterns in DOM and GHG are predominantly governed by local-scale drivers such as pool morphometry.

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No description available.