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Thesis (M.S.)--Bowling Green State University, 2006. / Document formatted into pages; contains xii, 64 p. Includes bibliographical references.

The detrimental effects of tributyltin (TBT) have been recorded on many marine organisms. As a result the UK Government imposed a partial ban on the use of organotin antifouling paints on boats less than 25 m in length, in 1987. In 1988 the Isle of Man Government followed suit introducing a licensing procedure restricting all uses of organotins. At concentrations less than 0.5 ng Sn/I female Nucella lap/Nus develop imposex - the superimposition of male sexual characteristics. To date there have been few studies measuring the recovery of Nucella populations after the introduction of restrictions. This study produces evidence of the extent of recovery in Nucella populations from sites in the south-west of England and on the Isle of Man. The recovery observed was measured by decreasing values of relative penis size, vas deferens sequence and the percentage of sterile adult females in the population. Following the 1987 ban the recovery of Nucella populations in the south-west has shown a linear response allowing predictions to be made for the time scale of complete recovery. In addition concentrations of TBT in the water and tissues of selected indicator organisms also showed decreases. Around the Isle of Man the illegal use of TBT paints was identified and later discouraged by the Marine Administration which was followed by a reduction in TBT concentrations in the water at sites around the Isle of Man. Levels of imposex in dogwhelk populations around the Isle of Man have decreased. Although effects of TBT on Nuce/la have been well documented at the cellular and individual level, the knock on effects on the community have not been investigated. Manipulative field experiments were used to demonstrate the role of Nucella lapd/us in structuring shore communities to allow predictions of the effect of TBT to be made. Rather than using the traditional approach of fences and cages, dogwhelks were removed by hand on regular visits to experimental sites creating treatments with reduced abundances of dogwhelks akin to shores affected by TBT. The role of Nucel/a was examined at different stages of a cycle existing on moderately exposed Manx shores where Fucus vesiculosus and Semibe/anus balanoides fluctuate in abundance. The removal of dogwhelks increased the abundance of Semibalanus ba/anoides on the shore and as a result likelihood of algal escapes from grazing by Patella vulgate also increased. In addition the removal of Nucela increased the size and longevity of newly established Fucus vesiculosus clumps. In a factorial experiment the role of Patella vulgate and Nucella lapillus were examined simultaneously. Nuce/la was found to have an significant effect but less than that of Patella. The presence of Nucella did, however, mediate the effect of Patella. In addition Nucella was found to have a direct effect on the level of Semibalanus balanoides settlement in the field with the number of barnacles settling in cleared areas being reduced on areas which had been previously occupied by Nucella.

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Biofouling impedes the performance of membrane bioreactors. In this study, we investigated the antifouling effects of polysulfone membranes that were modified by 1,2,3-triazole and palladium nanoparticles. The membranes to be tested were embedded within a drip flow biofilm reactor, and Pseudomonas aeruginosa PAO1 was inoculated and allowed to establish biofilm on the tested membranes. It was found that 1,2,3-triazole and palladium nanoparticles can inhibit the bacterial growth in aerobic and anaerobic conditions. The decrease in bacterial growth was observed along with a decrease in the amount of total polysaccharide and Pel polysaccharide within the biofilm matrix but not the protein content.

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Autor no autoriza el acceso a texto completo de su documento hasta el 20/1/2021. / Magíster en Ciencias de la Ingeniería, Mención Química / Ingeniero Civil Químico / La acuicultura en Chile es el cuarto rubro exportador más importante, lo que ha hecho necesario el desarrollo de tecnologías que hagan más eficientes sus procesos. En particular, la proliferación de organismos sobre las mallas de cultivo (biofouling) es uno de los problemas relevantes que la tecnología tiene el desafío de resolver. Se trata de una dificultad tanto ambiental como económica, por lo que las estrategias de mitigación se vuelven fundamentales. El objetivo de este trabajo es desarrollar un material polimérico, con partículas de cobre incorporadas, que tenga acción antifouling en las mallas de cultivo producto de la liberación de iones cúpricos. Para llevar a cabo dicho objetivo, se procedió a adquirir y caracterizar tres partículas de cobre metálico con morfología y tamaño diferentes. Por otra parte, se sintetizaron tres partículas mediante la inmersión de algunos soportes inorgánicos (zeolita, óxido de silicio y nanotubos de carbono) en una solución de acetato de cobre. Las partículas obtenidas con el mencionado método, resultaron tener sales de cobre sobre los soportes inorgánicos utilizados. Para cuantificar el potencial anti-biofouling de las partículas adquiridas y sintetizadas, se midió el proceso de liberación de iones cúpricos en agua desionizada. El resultado de esta cuantificación es que las partículas adquiridas liberan iones cúpricos de forma más lenta y, por otra parte, que la cantidad de iones cúpricos liberados al final del ensayo, puede ser explicada mediante un modelo que supone una fase heterogénea en equilibrio, con especies iónicas presenten en la solución. Con las partículas adquiridas y sintetizadas, posteriormente se elaboraron compósitos poliméricos de poliamida y polietileno con 10% en peso de partículas. A partir de lo anterior, se procedió a medir la tasa de liberación de los materiales elaborados en agua de mar, para evaluar si estos superan el umbral de liberación de iones cúpricos, para obtener acción antifouling. El resultado es que en el mejor de los casos, solo superan dicho valor crítico hasta el quinceavo día y la tasa de liberación de iones cúpricos, mejora con el aumento de la polaridad de la matriz polimérica, el aumento del porcentaje de cobre de los rellenos y su disminución de la densidad. A partir de los resultados obtenidos de los ensayos de liberación desde los compósitos con partículas de cobre, y considerando que el polímero más utilizado en la industria acuícola es el polietileno, se evaluó la acción antifouling de algunos de ellos durante dos meses, midiendo las unidades formadoras de colonias por unidad de superficie al final del ensayo. Se encontró que las diferencias entre los blancos y las muestras, no son significativas, como es de esperarse tomando en consideración que estos compósitos solo superan el umbral de acción antifouling hasta el octavo día. Finalmente, la prolongación del tiempo en que la tasa de liberación está sobre el umbral, ayudará a que los materiales poliméricos con partículas de cobre, tengan una acción antifouling significativa. Frente a esto, la incorporación de un relleno como la celulosa, que se caracteriza por mejorar la captación de agua por compósitos poliméricos, ayudaría a prolongar el tiempo en que la tasa de liberación se encuentra sobre el umbral de acción antifouling.

Tributyltin is arguably the most toxic compound ever to be deliberately introduced into the marine environment as an ingredient of antifouling paints. It has had widespread toxic effects on a range of marine organisms, with some gastropod species being particularly sensitive. Effects of TBT on non-target species have resulted in partial bans on its use in many countries, so that new inputs to the water column have decreased in most areas. One of the physicochemical features of TBT is that it is readily sequestered by suspended particulates due to its low solubility and its hydrophobicity, therefore becoming incorporated into estuarine sediments. The availability of this sediment-bound TBT has been investigated through its potential for re-release back to the water column, and directly from the sediment using the sediment dwelling gastropod Hinia reticulata. The sorption process itself has been investigated using natural components to determine the sediment-water partition coefficient (Kd) together with factors affecting its magnitude. Sorption by sediments has been shown to be rapid (minutes), although the achievement of equilibrium may take longer (hours), and exhibits a Freundlich-like dependence on the TBT concentration due to the variable energies of TBT sorption sites on sediment particles. The major determinant of Kd is sediment type, greater adsorption occurring in fine-grained organic rich sediments compared to low organic sands; although both salinity and pH modify the degree of adsorption. The sorption process has been shown to be reversible, so that previously contaminated sediments may act as reservoirs of TBT, releasing the compound back to the overlying water for many years. Hinia reticulate has been shown to be an effective and quantitative accumulator of both dissolved and sediment-bound TBT, principally acquiring TBT from water across the respiratory surfaces. When additionally exposed to sediments, significantly higher body burdens were accumulated, with up to 80% of the total attributable to the sediment. Uptake of TBT across the surface of the headtfoot appears to be an important pathway for sediment-exposed Hinia reticulata, while the ingestion of contaminated sediment does not appear to occur. Hinia reticulata is capable of metabolising TBT to lesser butylated and presumably less toxic products which are excreted, making its accumulated body burdens responsive to changing environmental TBT levels, and increasing its value as a biomonitor When exposed to a range of TBT contaminated sediments, Hinia reticulata showed there to be greater TBT availability from sediments with a low sorptive capacity (sands), principally through desorption of TBT to the overlying water. Fine-grained organic-rich muds, which have a greater capacity for TBT, produced lower accumulated burdens in Hinia reticulata, but may represent more important long-term sources of TBT to benthic organisms in estuaries.