Knowledge of fine sediment delivery (both timing and loading) is fundamental to the assessment of non-point source pollution in estuarine environments. This study comprised three key components that led to the development of a fine sediment and particulate associated phosphorus budget in a typical agricultural estuary. Firstly, to explore catchment inputs, turbidity and flow were monitored continuously upstream of the freshwater/saline interface on the main stem channel of the south Devon River Avon, which drains a medium sized agricultural catchment (area 340 km2), in southwest UK. Thirty-five storms were studied in detail; and the hydrological and suspended sediment load response was observed to be highly variable. Suspended sediment concentrations (SSC) reached a maximum of 804 mg L-1 and sediment load varied from 3 to 227 t per hydrological event. Most sediment load was concentrated in winter months when competent flows occur frequently. Hydrological response was also variable in terms of lag, hydrograph shape and maximum discharge wherein the response to hydrological drivers was not consistent. Analysis of key storm parameters indicated that the hydrological response of the catchment was affected by the total amount of precipitation and antecedent rainfall history but the spatial pattern in rainfall across the catchment in relation to the spatial pattern of sediment sources was the key factor influencing total load. In the second component, examination of the sediment-associated phosphorus concentrations in the surface sediment in the Avon estuary was undertaken to evaluate spatial variation in concentration as influenced by the sediment storage dynamics of key geomorphological zones i.e. saltmarshes, intertidal flats and sandy shoals. Phosphorus concentrations ranged from 1524 to 68 mg kg-1 with higher concentrations found in saltmarsh. While there was no observed relationship between key sediment properties, particle size and total organic carbon within the different geomorphic units, a clear trend in particle size and particulate phosphorus concentration was observed longitudinally between mudflat zones linked to the sedimentation dynamics of the estuary. Furthermore, the relationship of particulate phosphorus concentration to organic matter content was modified by saltmarsh vegetation inputs to the sediment column. The final component of the work drew on evidence from a GIS and field-based survey to estimate (i) the total fine sediment and associated particulate phosphorus loading of the estuary and (ii), in conjunction with river flux data and literature evidence, the total fine sediment and PP storage and the annual sediment budget (inputs, storages and output) for the study estuary. The total amount of fine sediment stored in the estuary was ca. 99000 t which equated to 40 - 100 years of the annual sediment load of the river. Approximately 50% of all fine sediment that currently enters the estuary was estimated to be retained in storage supporting the important role of estuarine sediment sink zones in the attenuation of phosphorus. The total particulate phosphorus storage in estuary fine sediment was estimated to be 20 – 40 times the measured annual catchment particulate phosphorus input. Future changes in catchment sediment supply dynamics linked to catchment restoration programmes and soil conservation initiatives could destabilise estuarine sediment sinks and this has potentially important implications for future estuarine water quality. There is a need for further work on the potential bioavailability of estuarine sediment stored phosphorus.

Long-term morphological change in estuaries, of the order of 100 years, has developed into an area of significant research interest as a result of increased regulation and management of estuarine environments. The long-term behaviour of estuary morphology results from the net effects of perturbations induced by tidal, seasonal and episodic events, averaged over a longer period. Theoretically a dynamic equilibrium may exist between deposition and erosion when considered over a time period that is sufficiently long to encompass the cyclic variability that exists within an estuarine system. However the assemblage of physical processes required for a stable state to exist, and the causes of deviation from a stable state, are not well understood. The interaction of physical processes of tidal and wave action, and the influence of sea level rise and anthropogenic activity, with estuarine ecology and geology are largely responsible for the evolving state of an estuary. Although the physical processes of tidal movement and wave action are well known and documented, the interaction of these processes with factors controlling estuarine evolution over long time periods is less well understood. This thesis evaluates approaches to analysing historical data and applying computational methods to examine the interaction between factors forcing long-term estuary morphology. Historical data is of considerable value to analysis of long-term morphological change in estuaries, and forms a pre-requisite for developing understanding of the nature and causes of the long-term evolution of estuary morphology. However few data sets exist which cover a period of sufficient duration with sufficient detail to identify the processes forcing morphological change, so recourse to computational methods is required for the purpose of developing understanding of estuary behaviour. Several techniques are employed, including analysis of bathymetric data, calculation of analytical parameters and computational hydrodynamic simulations, to develop a case study of processes causing morphological change in the Mersey estuary over the last century. A major requirement for the approach adopted in this thesis is the identification and reduction of uncertainty. Areas of uncertainty are identified, and the results arising from various computational techniques employing different assumptions are examined within a framework enabling evaluation of the uncertainty arising from analysis and assumptions upon which it is reliant. Volumetric analysis demonstrates that morphological change is dominated by a trend of significant accretion between 1906-1977, with tidal volume reducing by approximately 10% (70Mm3). Previous research has identified the construction of training walls, between 1906-36 to stabilise the position of the low water channel in Liverpool Bay outside the estuary, as a probable cause of perturbation. Changes to tidal flow and related sediment transport patterns outside the estuary resulting from training wall construction are examined with regard to the stability of the estuary system. The results from computational hydrodynamic models representing the years 1906, 1936 and 1977 quantifying potential changes in sediment transport pathways from outside the estuary indicate a significant increase in potential sediment supply to the mouth of the estuary during the period of peak accretion. However, these changes cannot be solely attributed to construction of the training walls, but result from the combined effect of training wall construction and dredging activity in the sea approach channels. Furthermore, it is not simply changes in tidal flow characteristics that cause sedimentation but also the existence of salinity induced gravitational circulation within the estuary and the wider Liverpool Bay system that acts as an important mechanism for importing sediment into the estuary. Evidence for evolution towards a stable estuary state is provided by derivation of a sediment budget demonstrating a negligible net flux of sediment into the estuary between 1977-1997. The establishment of a steady state is attributed to a reduction in the calculated transport of sediment, from west to east, across Liverpool Bay reducing the supply of sediment to the estuary mouth.

No description available.

Este trabalho investigou a diversidade microbiana e a filogenia de arquéias e bactérias em consórcios anaeróbios metanogênicos, originados de sedimentos estuarinos enriquecidos com pentaclorofenol (PCP) e 2,6-diclorofenol (2,6-DCP). Para tanto foram construídas bibliotecas genômicas e utilizados métodos moleculares independentes de cultivo como a Eletroforese em Gel de Gradiente Desnaturante (DGGE) e o seqüenciamento de segmentos específicos do DNAr 16S microbiano. Os resultados da DGGE permitiram verificar alterações na estrutura das comunidades microbianas, as quais provavelmente ocorreram devido às adversidades ocorridas nos sistemas durante o período de incubação como a entrada de oxigênio nos frascos e o acúmulo de compostos clorados no meio de cultivo, principalmente o 2,6-DCP. A estimativa da diversidade beta, realizada pela comparação dos padrões de bandas da DGGE, também permitiu inferir que as alterações nas composições das comunidades de arquéias e bactérias foram devidas às duas estratégias empregadas para o enriquecimento da microbiota autóctone do estuário estudado, ou seja, a pasteurização/não pasteurização das amostras de sedimentos estuarinos. Os resultados das análises filogenéticas revelaram que as seqüências analisadas dos clones bacterianos foram relacionadas ao grupo das bactérias Gram-positivas com baixo conteúdo de G+C pertencentes à Ordem Clostridiales (100%) do Filo Firmicutes e as das arquéias relacionadas ao grupo das metanogênicas pertencentes às Ordens Methanobacteriales (7,1%), Methanosarcinales (14,3%), Methanomicrobiales (57,1%) e arquéias não identificadas (21,4%) do Filo Euryarchaeota. Em relação às bactérias, alguns clones foram identificados como pertencentes aos gêneros Sedimentibacter, Clostridium e Alkalibacter, os quais são representados por microrganismos que apresentam metabolismo fermentativo e requerem a presença de extrato de levedura para o crescimento. Provavelmente as bactérias analisadas neste trabalho fermentaram a glicose e o piruvato, os quais foram utilizados como doadores de elétrons, com conseqüente produção de lactato, etanol, butirato, acetato, formiato e hidrogênio/gás carbônico, que podem ter sido utilizados por outros grupos de microrganismos no processo global da digestão anaeróbia. Tais bactérias foram importantes para o processo global de degradação dos clorofenóis, pois também utilizaram como doadores de elétrons os produtos parcialmente degradados por outras bactérias fazendo com que não houvesse acúmulo desses compostos no sistema. Enquanto que algumas arquéias foram relacionadas a organismos hidrogenotróficos pertencentes aos gêneros Methanoculleus e Methanocalculus, Methanobacterium, e acetotróficos do gênero Methanosaeta, as quais utilizaram como substratos para a metanogênese os subprodutos da fermentação bacteriana, ou seja, o \'H IND.2\'/\'CO IND.2\', o formiato e o acetato, contribuindo assim para a manutenção do equilíbrio das demais reações ocorridas no sistema. Desta forma, os dados obtidos neste trabalho poderão auxiliar na compreensão do funcionamento de ecossistemas contaminados por compostos clorados, bem como contribuir para o desenvolvimento de novos processos biotecnológicos aplicados aos problemas ambientais. / This work aimed to investigate microbial diversity and phylogeny of archaea and bacteria microrganisms methanogenic in estuarine sediment samples enriched with organic sources under methanogenic and halophlic conditions. The samples were obtained from previous study on anaerobic degradation of pentachlorophenol (PCP) and 2,6-dichlorophenol (2,6-DCP). Microbial studies were done by the molecular methods without cultivation requirement, Denaturing Gradient Del Electrophoresis (DGGE) and specific segments of 16S rDNA sequencing. DGGE-profile showed structure changes in microbial community. Probably, as a consequence of \'O IND.2\' intake and accumulation of chlorinated compounds, mainly 2,6-DCP, in the culture medium. The beta diversity estimation showed that changes in arquaea and bacteria communities probably occurred as a consequence of the two enrichment strategies used for estuarine indigenous microorganisms, pasteurization and non-pasteurization of the estuarine sediments samples. Phylogenetic analysis indicated the presence of gram-positive bacterium with low G+C content related to Clostridiales Order (100%) belonging to Firmicutes Phylum, as well as related to methanogenic archaea from Methanobacteriales (7,1%), Methanosarcinales (14,3%) and Methanomicrobiales (57,1%) Order. Non-identified archaeas from Euryarchaeota Phylum were also found (21,4%). Concerning to bacterias, it was identified clones related to genera Sedimentibacter, Clostridium and Alkalibacter, which have fermentative metabolism and require yeast extract to grow. Probably, bacterial cells analised in this work fermented glucose and pyruvate producing lactate, ethanol, butirate, acetate, formiate and hydrogen/carbon dioxide. All these products could be used for other microbial groups in the global process of anaerobic digestion. The bacterial microorganisms were important to global process of chlorophenol degradation because contributed in the overall process utilizing the products partially degraded by other bacterias and preventing its accumulation in the system. Identified archaeal cells were related to hydrogenotrophs microorganisms of the genera Methanosaeta, Methanoculleus, Methanocalculus and Methanobacterium, which utilized the bacterial fermentation sub-products as acetate, \'H IND.2\'/\'CO IND.2\' and formiate as substrate for the methanogenesis, contributing for the maintenance of the balance of other reactions occurred in the system. The results of this work give advanced knowledge about understanding biotechnological process of contaminated ecosystems by chlorinated compounds. Therefore, it could contribute to development of new biotechnological processes applied to environmental problems.

Este trabalho investigou a diversidade microbiana e a filogenia de arquéias e bactérias em consórcios anaeróbios metanogênicos, originados de sedimentos estuarinos enriquecidos com pentaclorofenol (PCP) e 2,6-diclorofenol (2,6-DCP). Para tanto foram construídas bibliotecas genômicas e utilizados métodos moleculares independentes de cultivo como a Eletroforese em Gel de Gradiente Desnaturante (DGGE) e o seqüenciamento de segmentos específicos do DNAr 16S microbiano. Os resultados da DGGE permitiram verificar alterações na estrutura das comunidades microbianas, as quais provavelmente ocorreram devido às adversidades ocorridas nos sistemas durante o período de incubação como a entrada de oxigênio nos frascos e o acúmulo de compostos clorados no meio de cultivo, principalmente o 2,6-DCP. A estimativa da diversidade beta, realizada pela comparação dos padrões de bandas da DGGE, também permitiu inferir que as alterações nas composições das comunidades de arquéias e bactérias foram devidas às duas estratégias empregadas para o enriquecimento da microbiota autóctone do estuário estudado, ou seja, a pasteurização/não pasteurização das amostras de sedimentos estuarinos. Os resultados das análises filogenéticas revelaram que as seqüências analisadas dos clones bacterianos foram relacionadas ao grupo das bactérias Gram-positivas com baixo conteúdo de G+C pertencentes à Ordem Clostridiales (100%) do Filo Firmicutes e as das arquéias relacionadas ao grupo das metanogênicas pertencentes às Ordens Methanobacteriales (7,1%), Methanosarcinales (14,3%), Methanomicrobiales (57,1%) e arquéias não identificadas (21,4%) do Filo Euryarchaeota. Em relação às bactérias, alguns clones foram identificados como pertencentes aos gêneros Sedimentibacter, Clostridium e Alkalibacter, os quais são representados por microrganismos que apresentam metabolismo fermentativo e requerem a presença de extrato de levedura para o crescimento. Provavelmente as bactérias analisadas neste trabalho fermentaram a glicose e o piruvato, os quais foram utilizados como doadores de elétrons, com conseqüente produção de lactato, etanol, butirato, acetato, formiato e hidrogênio/gás carbônico, que podem ter sido utilizados por outros grupos de microrganismos no processo global da digestão anaeróbia. Tais bactérias foram importantes para o processo global de degradação dos clorofenóis, pois também utilizaram como doadores de elétrons os produtos parcialmente degradados por outras bactérias fazendo com que não houvesse acúmulo desses compostos no sistema. Enquanto que algumas arquéias foram relacionadas a organismos hidrogenotróficos pertencentes aos gêneros Methanoculleus e Methanocalculus, Methanobacterium, e acetotróficos do gênero Methanosaeta, as quais utilizaram como substratos para a metanogênese os subprodutos da fermentação bacteriana, ou seja, o \'H IND.2\'/\'CO IND.2\', o formiato e o acetato, contribuindo assim para a manutenção do equilíbrio das demais reações ocorridas no sistema. Desta forma, os dados obtidos neste trabalho poderão auxiliar na compreensão do funcionamento de ecossistemas contaminados por compostos clorados, bem como contribuir para o desenvolvimento de novos processos biotecnológicos aplicados aos problemas ambientais. / This work aimed to investigate microbial diversity and phylogeny of archaea and bacteria microrganisms methanogenic in estuarine sediment samples enriched with organic sources under methanogenic and halophlic conditions. The samples were obtained from previous study on anaerobic degradation of pentachlorophenol (PCP) and 2,6-dichlorophenol (2,6-DCP). Microbial studies were done by the molecular methods without cultivation requirement, Denaturing Gradient Del Electrophoresis (DGGE) and specific segments of 16S rDNA sequencing. DGGE-profile showed structure changes in microbial community. Probably, as a consequence of \'O IND.2\' intake and accumulation of chlorinated compounds, mainly 2,6-DCP, in the culture medium. The beta diversity estimation showed that changes in arquaea and bacteria communities probably occurred as a consequence of the two enrichment strategies used for estuarine indigenous microorganisms, pasteurization and non-pasteurization of the estuarine sediments samples. Phylogenetic analysis indicated the presence of gram-positive bacterium with low G+C content related to Clostridiales Order (100%) belonging to Firmicutes Phylum, as well as related to methanogenic archaea from Methanobacteriales (7,1%), Methanosarcinales (14,3%) and Methanomicrobiales (57,1%) Order. Non-identified archaeas from Euryarchaeota Phylum were also found (21,4%). Concerning to bacterias, it was identified clones related to genera Sedimentibacter, Clostridium and Alkalibacter, which have fermentative metabolism and require yeast extract to grow. Probably, bacterial cells analised in this work fermented glucose and pyruvate producing lactate, ethanol, butirate, acetate, formiate and hydrogen/carbon dioxide. All these products could be used for other microbial groups in the global process of anaerobic digestion. The bacterial microorganisms were important to global process of chlorophenol degradation because contributed in the overall process utilizing the products partially degraded by other bacterias and preventing its accumulation in the system. Identified archaeal cells were related to hydrogenotrophs microorganisms of the genera Methanosaeta, Methanoculleus, Methanocalculus and Methanobacterium, which utilized the bacterial fermentation sub-products as acetate, \'H IND.2\'/\'CO IND.2\' and formiate as substrate for the methanogenesis, contributing for the maintenance of the balance of other reactions occurred in the system. The results of this work give advanced knowledge about understanding biotechnological process of contaminated ecosystems by chlorinated compounds. Therefore, it could contribute to development of new biotechnological processes applied to environmental problems.