Polymer-coated controlled-release fertilizers (PCFs) are the most widely used class of fertilizers in the production of container-grown nursery plants. Nutrient release from PCFs is primarily influenced by temperature. The objective of this study was to determine the influences of temperature and time on the nutrient release patterns of three PCFs (each with a rated longevity of 8-9 months), each using a different coating technology: Osmocote Plus™ 15N-3.93P-9.96K, Polyon™ 18N-2.62P-9.96K, and Nutricote™ 18N-2.62P-6.64K. The first three experiments investigated the effects of time on long-term nutrient release. In Expt. 1, each of the three PCFs were placed in flasks of distilled water maintained at 40°C for 22 weeks. Fertilizer solutions were poured off at bi-weekly intervals and measured for electrical conductivity (EC) and NO3-N, NH4-N, P, K, Fe, Mn, Cu, and Zn concentrations. Overall, nutrient release for the three PCFs was higher and more variable in the first eight weeks than later in the experiment. Polyon's™ macronutrient release was generally more gradual than that of the other products. Micronutrient release patterns varied substantially between fertilizers and nutrients. In Expt. 2, pine bark (PB)-filled containers were amended with the three PCFs and irrigated regularly in a greenhouse. PCFs were removed from containers when Osmocote Plus'™ NO₃-N supply was ~66% expended and analyzed for EC, NO₃-N, NH₄-N, and P concentration. Except for P, the percentage of each nutrient remaining was roughly comparable to those remaining at the corresponding stage of Expt. 1, suggesting that PCF nutrient release behavior in the laboratory method is comparable with nutrient release behavior in PB in the greenhouse. At the end of Expts. 1 and 2, Osmocote Plus™ had expended a higher percentage of its nutrients than the other fertilizers. In Expt. 3, substrate solutions were collected weekly from PB-filled containers (same treatments as in Expt. 2) and EC was determined. The substrate solution EC of Osmocote Plus™-fertilized PB began to decline sooner than that of the other fertilizers. Overall, these three experiments led to the conclusion that Osmocote Plus™ nutrient release declines more quickly than does Polyon™ or Nutricote™, while Polyon™ has the most gradual nutrient release pattern. The objective of the second set of experiments was to determine the effects of temperature on short-term nutrient release. In Expt. 4, 14 g of each PCF was maintained at 40°C until ~33% of the NO3-N content in Osmocote Plus™ was expended. Each fertilizer was then placed in a sand column and leached with distilled water at ~100 mL/h. Columns were then incrementally subjected to a simulated diurnal container temperature change from 20°C to 40°C and back to 20°C over a period of 20 h. Leachate was collected hourly and measured for soluble salts and NO₃-N and NH₄-N concentrations. For all fertilizers, nutrient release increased and decreased with the respective increase and decrease in temperature. Nutrient release patterns of the three fertilizers were significantly different, with Osmocote Plus™ showing the greatest overall change in nutrient release between 20°C and 40°C and Nutricote™ the least. In Expt. 5, PCFs were placed in flasks of distilled water in constant temperature baths. Initially, fertilizers were held at 40°C for three days and then at temperatures of 22, 28, 34, or 40°C for two weeks. Fertilizer solutions were poured off after the first and second weeks. Only solutions from the second week were analyzed for soluble salts and NO₃-N, NH₄-N, P, and K concentrations. For Osmocote Plus™ and Polyon™, there was a 29% to 86% (depending on the nutrient measured) mean increase in nutrient release between 22°C and 40°C, whereas for Nutricote™ there was a 345% to 364% (depending on the nutrient measured) mean increase. The overall mean increases in nutrient release in Expt. 4 were between 1032% and 4023%, whereas the mean increases in Expt. 5 were between 29% and 364%. In summary, the second set of experiments found that PCF nutrient release was highly sensitive to diurnal temperature changes. / Master of Science

Pesticide runoff from agricultural applications poses a potential threat to water quality in the world heritage listed Great Barrier Reef (GBR) and sensitive monitoring tools are needed to facilitate effective monitoring of these pollutants. This thesis has worked to advance passive sampling tools for monitoring trace organic pollutants and their potential impacts on the GBR. The suitability of several available passive sampling tools for detecting trace concentrations of target pesticide analytes was investigated in a laboratory calibration chamber before experiments were conducted to further understanding of the response of Chemcatcher passive samplers in environmental conditions likely to be experienced in the GBR. Passive samplers were deployed in a survey of pesticides in the GBR environment and extracts were applied in bioassays to investigate their application for predicting mixture toxicity to GBR biota. When employed and interpreted appropriately, passive sampling tools have been shown to provide for sensitive and reproducible detection of organic pollutants in relatively pristine environments. While considerable research has been conducted into the performance and theory of analyte uptake by a range of passive sampling devices, several key knowledge gaps existed and were addressed in this study. The applicability of the performance reference compound (PRC) concept as an in situ calibration method for passive samplers using Empore Disk sampling phases (Chemcatchers) to monitor polar compounds was investigated. This experiment showed that while uptake of pesticides was linear and reproducible, PRC loss was not linear, meaning that the dissipation rates of these PRCs cannot be used to estimate the effect of field exposure conditions on uptake rates. An alternative in situ calibration technique using PRC loaded polydimethylsiloxane (PDMS) disks deployed alongside the Chemcatchers as a surrogate calibration phase has been tested and shows promise for future applications. Pesticide concentrations in waters flowing to the GBR have been shown to undergo dramatic fluctuations over short time periods and the potential for these conditions to limit the integrative period of sampling was investigated by simulating a changing concentration event in a calibration chamber. The ability for samplers to predict average concentrations was dependant on the deployment configuration (with or without membrane) used and the period of deployment relative to the changing concentration event. Passive samplers were employed in a survey of pesticides in GBR waters during a wet and dry season at river mouths, two nearshore regions and an offshore region. The nearshore marine environment was shown to be contaminated with pesticides in both the dry and wet seasons (average water concentrations of 1.3-3.8 ng L-1 and 2.2-6.4 ng L-1, respectively), while no pesticides were detected further offshore. Continuous monitoring of two rivers over 13 months showed waters flowing to the GBR were contaminated with herbicides (diuron, atrazine, hexazinone) year round, with highest average concentrations present during summer months (350 ng L-1). The use of passive samplers has enabled identification of insecticides in GBR waters which have not been reported in the literature previously. Extracts from passive samplers deployed at three sites in the GBR were applied to bioassays targeting integral life stages or functions of coral reef biota: scleractinian coral larvae, sea urchin larvae, a marine diatom and marine bacteria. The results demonstrate the utility of pairing passive sampling with bioassays and reveal that mixtures of organic pollutants in the GBR have the potential to cause detrimental effects to coral reef biota. This research outlines an approach that reduces one of the levels of simplification of risk assessment of pollutants to ecosystems by incorporating mixtures of chemicals present in the environment. The use of passive sampler extracts in toxicity testing allows pollutant mixtures to be assessed at a range of enrichment factors and, with the inclusion of biota from the ecosystem of concern, improves the relevance of results for predicting real world effects. The findings of this thesis are intended to be used to improve the application of passive sampling tools for routine monitoring to provide managers with understanding of the pesticides present, the potential effects of those pollutant mixtures and feedback on the efficacy of implemented land management practices in halting and reversing the impacts of pesticides on the GBR.

Os comprimidos osmóticos do tipo bicamada ou \"push pull\" são sistemas reservatórios constituídos de um núcleo bicamada, circundado por uma membrana semipermeável e com um orifício de liberação perfurado a laser que permitem a liberação do fármaco através da cinética de ordem zero. Este sistema possui a vantagem de apresentar uma liberação controlada e não influenciada pelos fatores fisiológicos do trato gastrointestinal, permitindo aplicações terapêuticas para novos fármacos e inclusive para fármacos já existentes. O presente projeto contemplou as etapas de desenvolvimento, caracterização e avaliação de um sistema osmótico do tipo bicamada ou \"push pull\", para veiculação do atenolol, um beta bloquador de grande importância na terapia antihipertensiva. Após a padronização e validação da metodologia analítica, estudos de compatibilidade entre o fármaco e os excipientes através da análise calorimétrica e espectroscopia no infravermelho (pré-formulação), a produção, a caracterização da membrana de revestimento e, por fim, a avaliação do desempenho dos núcleos osmóticos foram realizados. Assim, três lotes, com 4kg cada, foram produzidos para determinação do peso médio e do ferramental adequados, além da proporção entre os excipientes da formulação. O processo de compressão deu origem aos núcleos osmóticos do tipo bicamada que foram submetidos à avaliação físico-química como determinação do peso médio, da dureza, da friabilidade e da espessura. Além disso, padronizou-se o processo de revestimento dos núcleos com membrana semipermeável e avaliou-se o perfil de captação de água dos núcleos resultantes (\"Swelling\"). A membrana de revestimento foi submetida à microscopia eletrônica de varredura (MEV), análise por adsorção de nitrogênio e porosimetria de mercúrio para verificação da distribuição e tamanho médio dos poros. Para a obtenção do orifício de liberação padronizou-se a quantidade de radiação a laser suficiente para perfuração da membrana semipermeável que envolve os núcleos. Após a perfuração a laser, os núcleos foram submetidos então ao estudo de liberação in vitro para avaliação da influência do diâmetro de orifícios, do número de orifícios, da espessura da membrana semipermeável, da hidrodinâmica do meio de dissolução e da influência térmica na velocidade de liberação do fármaco. A cinética do tipo ordem zero e o controle da liberação do fármaco ao longo do tempo foram alcançados com sucesso a partir dos núcleos osmóticos produzidos no lote 03. / The push pull osmotic release tablets are bilayer core reservoir systems surrounded by semi permeable membrane and with one delivery hole where the drug is released through, following zero order release kinetics. This system has many advantages and two of them are the controlled drug release and independence of physiologically factors allowing many therapeutic applications to new one and known one drugs. This exclusive work proposed the development, characterization and evaluation of atenolol push pull osmotic system that is very important to antihypertensive treatment. After analytical standardization and validation activities, the pre-formulation studies using calorimetric and infra red spectroscopy techniques, manufacturing, semi permeable membrane characterization and finally osmotic tablets performance evaluation were performed. Batches about 4 kg each one were manufactured and tablets average weight, by-layer proportionality and suitable punches were chosen. Thus the osmotic tablets obtained by bi-layer press were physical and chemical evaluated (average weight, hardness, friability, and thickness). After that the tablets were submitted to a coating process with semi permeable membrane and the uptake water profile (Swelling) was observed to characterize the membrane permeability. The semi permeable membrane was submitted also to scanning electron microscopy (SEM), nitrogen adsorption and mercury porosimetry techniques in order to characterize the porous average diameter and distribution. To produce the delivery hole in the drug layer semi permeable membrane the sufficient laser radiation amount was studied and determined. So the perforated osmotic tablets were submitted to in vitro drug release studies to evaluate the influence of hole diameter, hole number, coating thickness, medium hydrodynamic and temperature stress responsible for drug release modifications. Finally the controlled delivery and the zero order drug release kinetics were achieved successfully from osmotic tablets developed and produced in the third bath. This third bath was the result of the factors comprehension and the optimization of the early ones.

Contaminants can exist in a wide range of states in aqueous environments, especially in surface waters. They can be freely dissolved or associated with dissolved or particulate organic matter depending on their chemical and physical characteristics. The freely dissolved fraction represents the most bioavailable fraction to an organism. These freely dissolved contaminants can cross biomembranes, potentially exerting toxic effects. Passive sampling devices (PSDs) have been developed to aid in sampling many of these contaminants by having the ability to distinguish between the freely dissolved and bound fraction of a contaminant. A new PSD, the Lipid-Free Tube (LFT) sampler was developed in response to some of the shortcomings of other current PSD that sample hydrophobic organic contaminants (HOCs). The device and laboratory methods were original modeled after a widely utilized PSD, the semipermeable membrane device (SPMD), and then improved upon. The effectiveness, efficiency, and sensitivity of not only the PSD itself, but also the laboratory methods were investigated. One requirement during LFT development was to ensure LFTs could be coupled with biological analyses without deleterious results. In an embryonic zebrafish developmental toxicity assay, embryos exposed to un-fortified LFT extracts did not show significant adverse biological response as compared to controls. Also, LFT technology lends itself to easy application in monitoring pesticides at remote sampling sites. LFTs were utilized during a series of training exchanges between Oregon State University and the Centre de Recherches en Ecotoxicologie pour le Sahel (CERES)/LOCUSTOX laboratory in Dakar, Senegal that sought to build "in country" analytical capacity. Application of LFTs as biological surrogates for predicting potential human health risk endpoints, such as those in a public health assessment was also investigated. LFT mass and accumulated contaminant masses were used directly, representing the amount of contaminants an organism would be exposed to through partitioning assuming steady state without metabolism. These exposure concentrations allow for calculating potential health risks in a human health risk model. LFT prove to be a robust tool not only for assessing bioavailable water concentrations of HOCs, but also potentially providing many insights into the toxicological significance of aquatic contaminants and mixtures. / Graduation date: 2010

Os comprimidos osmóticos do tipo bicamada ou \"push pull\" são sistemas reservatórios constituídos de um núcleo bicamada, circundado por uma membrana semipermeável e com um orifício de liberação perfurado a laser que permitem a liberação do fármaco através da cinética de ordem zero. Este sistema possui a vantagem de apresentar uma liberação controlada e não influenciada pelos fatores fisiológicos do trato gastrointestinal, permitindo aplicações terapêuticas para novos fármacos e inclusive para fármacos já existentes. O presente projeto contemplou as etapas de desenvolvimento, caracterização e avaliação de um sistema osmótico do tipo bicamada ou \"push pull\", para veiculação do atenolol, um beta bloquador de grande importância na terapia antihipertensiva. Após a padronização e validação da metodologia analítica, estudos de compatibilidade entre o fármaco e os excipientes através da análise calorimétrica e espectroscopia no infravermelho (pré-formulação), a produção, a caracterização da membrana de revestimento e, por fim, a avaliação do desempenho dos núcleos osmóticos foram realizados. Assim, três lotes, com 4kg cada, foram produzidos para determinação do peso médio e do ferramental adequados, além da proporção entre os excipientes da formulação. O processo de compressão deu origem aos núcleos osmóticos do tipo bicamada que foram submetidos à avaliação físico-química como determinação do peso médio, da dureza, da friabilidade e da espessura. Além disso, padronizou-se o processo de revestimento dos núcleos com membrana semipermeável e avaliou-se o perfil de captação de água dos núcleos resultantes (\"Swelling\"). A membrana de revestimento foi submetida à microscopia eletrônica de varredura (MEV), análise por adsorção de nitrogênio e porosimetria de mercúrio para verificação da distribuição e tamanho médio dos poros. Para a obtenção do orifício de liberação padronizou-se a quantidade de radiação a laser suficiente para perfuração da membrana semipermeável que envolve os núcleos. Após a perfuração a laser, os núcleos foram submetidos então ao estudo de liberação in vitro para avaliação da influência do diâmetro de orifícios, do número de orifícios, da espessura da membrana semipermeável, da hidrodinâmica do meio de dissolução e da influência térmica na velocidade de liberação do fármaco. A cinética do tipo ordem zero e o controle da liberação do fármaco ao longo do tempo foram alcançados com sucesso a partir dos núcleos osmóticos produzidos no lote 03. / The push pull osmotic release tablets are bilayer core reservoir systems surrounded by semi permeable membrane and with one delivery hole where the drug is released through, following zero order release kinetics. This system has many advantages and two of them are the controlled drug release and independence of physiologically factors allowing many therapeutic applications to new one and known one drugs. This exclusive work proposed the development, characterization and evaluation of atenolol push pull osmotic system that is very important to antihypertensive treatment. After analytical standardization and validation activities, the pre-formulation studies using calorimetric and infra red spectroscopy techniques, manufacturing, semi permeable membrane characterization and finally osmotic tablets performance evaluation were performed. Batches about 4 kg each one were manufactured and tablets average weight, by-layer proportionality and suitable punches were chosen. Thus the osmotic tablets obtained by bi-layer press were physical and chemical evaluated (average weight, hardness, friability, and thickness). After that the tablets were submitted to a coating process with semi permeable membrane and the uptake water profile (Swelling) was observed to characterize the membrane permeability. The semi permeable membrane was submitted also to scanning electron microscopy (SEM), nitrogen adsorption and mercury porosimetry techniques in order to characterize the porous average diameter and distribution. To produce the delivery hole in the drug layer semi permeable membrane the sufficient laser radiation amount was studied and determined. So the perforated osmotic tablets were submitted to in vitro drug release studies to evaluate the influence of hole diameter, hole number, coating thickness, medium hydrodynamic and temperature stress responsible for drug release modifications. Finally the controlled delivery and the zero order drug release kinetics were achieved successfully from osmotic tablets developed and produced in the third bath. This third bath was the result of the factors comprehension and the optimization of the early ones.