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To assess the relative contribution of phosphorus release from sediment in Cootes Paradise Marsh, I first examined spatial and temporal variability of laboratory-measured release rates from sediment samples collected from 12 sites within the wetland (Chapter 1 ). The microbial communities from these 12 sites were characterized on the basis of sole-carbon-source utilization using BIOLOG GN plates containing 95 substrates. Results from these experiments were entered into a principal component analysis and the release rates for all sites were regressed against corresponding PC 1 and PC2 scores (Chapter 2). Differences in microbial physiology as defined by PC 1 and PC2 scores accounted for 49% and 53%, respectively of the variation in phosphorus release rates. Using stepwise multiple regression, I concluded that the key determinants of laboratory-derived release rates from West Pond sediment (a highly eutrophic site within Cootes Paradise Marsh) are oxic state, ambient temperature and time of sediment collection (Chapter 3). Using this information I developed a multivariate model to predict release rates. This model, along with 2 alternative approaches, was used to estimate the extent of internal loading (kg d-1) in Cootes Paradise Marsh (Chapter 4). Method 1 was a highly controlled, static approach and resulted in an internal load of 11 .6 kg d-1, which was attributed to diffusion. The remaining two methods were more dynamic in nature as they took into account temporal variation, ambient temperature and the development of anoxia. Using Method 2, I estimated an internal load of 7.8 to 8.5 kgd-1, which was based on empirically-derived laboratory release rates. Method 3 consisted of the predictive model from which I estimated an internal load of 6.7 kgd-1• I attributed the release from the latter two methods to microbial mineralization processes. Based on this work and a previous estimate of internal loading in Cootes Paradise Marsh (Prescott & Tsanis 1997), I concluded that mineralization accounts for 22.3% of total phosphorus loading to the system, preceded only by urban runoff ( 41% ). / Thesis / Master of Science (MS)

A dynamic model is developed for the purpose of predicting stability characteristics of an industrial-scale, swirl-stabilized premixed combustor located at the National Energy Technology Laboratory (NETL) in Morgantown, WV. The model consists of modular blocks that assemble into an open-loop transfer function depicting the frequency response of the thermoacoustic system. These blocks include the system acoustic response to unsteady heat release forcing, the air-side coupling of acoustic particle velocity to inlet fuel mass fraction, transport delays present in the mixing nozzle and combustion chamber, and dynamic heat release excitation from unsteady inlet fuel mass fraction. By examing the frequency response with linear stability techniques, the existence of limit cycles due to linear instabilities is predicted. Further, the frequency response analysis is used to predict limit cycle frequencies in the case of predicted instability. The analysis predictions are compared with the results of tests performed at NETL, demonstrating a capability of replicating many of the observed stability characteristics. / Ph. D.

Novel coatings have been designed to solve problems associated with biofouling of marine structures, particularly ship hulls. The best candidates to date are multilayered coatings incorporating silicone rubber technology. These materials are efficient because they exhibit excellent release properties. However, they are very soft and tend to be more susceptible to various forms of mechanical damage. Fundamental analysis of the durability of these coatings has been done using standard laboratory tests. Simulative studies are essential to screen candidates as well as to predict the true life of the systems. The goal of this project was to develop a testing protocol for the evaluation of the durability of elastomeric easy release coatings and to implement it on selected candidate coatings. A brushing apparatus was designed and built to simulate the cleaning processes of ship hulls. Wear was measured with profilometry. The proposed methodology is valuable to study the processes of wear of the coatings, to screen various materials and to identify parameters, either functional or material, which would directly affect their durability. Two groups of candidate coatings were tested: the EXS series and the NRL series. The EXS samples showed better wear resistance than the NRL samples and showed no dependence on the rotational speed of the brushes. The NRL samples showed that increasing the sliding speed resulted in a decrease in wear. An increase in the applied load resulted in increased wear for both sample series. The effect of coating thickness was also investigated and discrimination between the proposed coatings could not be established because the tips of the bristles were sharp and irregular. Scratches matching the path of the brush bristles were observed in the wear scars of both sample types under all load and speed conditions. The NRL samples also exhibited ridges perpendicular to the sliding direction similar to the abrasion pattern. / Ph. D.

Recent efforts to restore depressed or extirpated populations of freshwater mussels have focused on artificial propagation as an effective and practical conservation strategy. Although artificially cultured juveniles have been produced and released to the wild, no study has investigated the best time of year or the best developmental stage to release these juveniles. Several experiments were conducted to gain knowledge of appropriate culture and release techniques. Juvenile wavyrayed lampmussels (<I>Lampsilis fasciola</I>) were artificially propagated in the laboratory and subsequently release into a fish hatchery raceway during June, September and March. Juveniles released in June experienced a gradual decline in survival rate, with 50% survival after 72 days and stable survival thereafter until 200 days. Juveniles released in September and March experienced high mortality within the first month, and were unsuccessful in surviving the cold water conditions typical of those seasons. Temperature was strongly associated with growth; thus, juveniles released in June exhibited considerably greater growth than those released in September and March. Survival was positively correlated with shell length in the first 32 days post-metamorphosis. Fall and spring survival values, shell length-frequency data, and a significant increase in overwinter mean shell length (p = 0.045) suggest that overwinter survival is size-dependent. Survival rates of juveniles released in June exceed those of previous culture studies reported in the literature. From these results, I suggest that the best time for release of propagated juvenile freshwater mussels should be at the beginning of the growing season in late spring, when water temperatures exceed 15 degrees C (plus/minus 1°C). Offspring of four, gravid female <I>L. fasciola</I> were tested to evaluate the extent of variability in growth and survival among brood stock. Comparison of growth and survival of progeny showed significantly lower performance of only one female (p < 0.05). Although results indicate variability in growth and survival among broods, it is not known whether heritabilities or physiological fitness caused this variability. Infested fish (IF), newly metamorphosed juveniles (NMJ) and juveniles cultured for 1 month (CJ) were released to a fish hatchery raceway in order to determine the most appropriate developmental stage to release juveniles. Significant differences were recorded among the three release methods, with CJ attaining the greatest growth (2.47 mm plus/minus 0.02), NMJ with the next best growth (1.86 mm plus/minus 0.02), and IF exhibiting the least growth (1.34 mm plus/minus 0.02) (p < 0.0001). Survival among release methods was not statistically different because of high variability within each release method. High mortality from predacious fish was presumably the cause of this variability. With minimal predation, L. fasciola experienced 82.2% (plus/minus 3.6) survival at 90 days. Survival of hatchery-reared juveniles was comparably higher than laboratory-reared juveniles, suggesting that culturing freshwater mussels in a hatchery raceway is a preferable alternative to laboratory culture. An experiment was conducted to compare growth of confined and unconfined juvenile L. fasciola released to a fish hatchery raceway. After 72 days, juveniles confined to small open dishes within the raceway (1.04 mm plus/minus 0.08) exhibited significantly less growth than juveniles released to the raceway that were not held in containers (2.15 mm plus/minus 0.07) (p < 0.0001). Results of additional comparisons with compiled growth data suggest that juvenile growth is retarded when cultured in small dishes. / Master of Science