In nuclear reprocessing, PUREX, a solvent extraction process, has long been the separation method employed for the separation of the bulk components of irradiated nuclear fuel (namely uranium and plutonium) from the fission products and other minor actinides produced during the fuel use. The uranium and plutonium constitutes approximately 96 % by mass of the irradiated fuel and for this to be removed, requires large volumes of extractant and equipment with large surface area contactors and therefore floor space requirements. The PUREX process has for nearly 60 years been the largely unchallenged separation technology for the reprocessing of irradiated fuel, for both nuclear weapon production and commercial nuclear power generation. The merits and ability of this process are unquestionable since it achieves the objectives of highly purified plutonium and uranium which both can be eventually recycled. Although well proven and predictable, the PUREX process is not without its challenges: the generation of significant quantities of highly active aqueous liquid containing fission products (FPs) and minor actinides (MAs), and the degradation of the solvent phase reagents and non-specific nature of the extractant TriButylPhosphate (TBP) may have contributed to only a fraction of the total annual output of irradiated fuel being reprocessed. Fission products are elements which are produced in a nuclear reactor and are the atomic fragments left after a large atomic nucleus (typically uranium-235) undergoes nuclear fission, splitting into two smaller nuclei, along with a few neutrons, the release of heat energy (kinetic energy of the nuclei), and gamma rays. Minor actinides such as neptunium, americium, curium, berkelium, californium, einsteinium, and fermium are the actinide elements in irradiated nuclear fuel other than uranium and plutonium; they are minor as they represent a very small proportion of actinides in comparison to U and Pu. This thesis explores the possibility of using a continuous chromatographic method to extract the lesser components of the irradiated fuel. One of the major problems with the use of chromatography as an industrial process is the expansion from the batch separations on the bench top to a continuous efficient process, capable of processing large volumes. This thesis, through existing concepts, will describe a proof of concept chromatographic separation of surrogates and isotopes of the components of irradiated fuels which can be readily scaled up to a continuous chromatographic separation. The project is a radical departure from PUREX and will offer many advantages over PUREX. It is based on the separation of FPs and MAs from uranium and plutonium isotopes using continuous chromatographic separation. This thesis assesses a number of commercial resins for their suitability for the proposed continuous chromatography reprocessing method. The experiments were all undertaken at elevated nitric acid concentrations and as such are describing interactions which are rarely required commercially and therefore seldom reported, with batch studies to assess separation factors between ions, uptake kinetics and isotherms over a range of nitric acid concentrations to more dynamic column breakthrough and eventually separations. The research demonstrates that a separation can be achieved at an elevated HNO3 concentration on a commercially available ion exchange resin.

No description available.

The impacts of Invasive Non-Native Species (INNS) are well documented, and INNS management is widely considered one of top threats to global biodiversity and ecosystem function. The American signal crayfish, Pacifastacus leniusculus, is a destructive invader of freshwater ecosystems. In Scotland, this species currently has a restricted distribution. Despite the known impacts and high rates of dispersal, little is being done to manage populations that threaten to spread into Scotland's economically important catchments. One barrier to action on the management of signal crayfish is uncertainty over the implementation and efficacy of control methods. Capture-mark-recapture analysis was used to estimate the size- and season-specific capture probabilities of three traditional and two novel mechanical removal methods. By simulating the effect of harvest with these removal methods on a density-independent population model, a range of optimal seasonal combinations of removal methods were derived. Little empirical evidence exists in compensatory density-dependent dynamics in signal crayfish. I found that the probability of an individual cannibalising was affected by its size and also the density of conspecifics around it. I trialled a seasonally optimal combination of removal methods in two populations, manipulating sections of stream with different crayfish removal intensities, and tracked the movements of marked individuals. There was a high rate of dispersal (33%) that was influenced by the quality of the patch it was leaving, dispersing to, and the intensities of removal applied to the stream sections. Crayfish had a greater probability of moving to high density sections with the highest removal treatment. My conclusions suggest that conventional removal efforts (trapping), may fail due to compensatory effects on mortality and dispersal, and that novel approaches such as targeting smaller size classes are required, but only after quantitative predictions and field trials.

The seasonal variation of anammox is yet to be comprehensively studied, unlike denitrification, the more traditional sink for fixed nitrogen. A seasonal study of anammox, denitrification and benthic oxygen consumption using the revised isotope pairing technique is presented in Chapter 2. Experimental temperature and NO3- concentration were kept constant throughout so that the capacity of the sediment for anammox could be estimated. Similar seasonal variations in the rates of anammox, denitrification and oxygen consumption suggest that anammox is controlled by the availability of organic carbon. Furthermore the effect of tidal inundation by overlying water rich in NO3- was investigated by measuring rates of anammox, denitrification and oxygen consumption at three tidal elevations throughout the year. A significant relationship between anammox and denitrification was established at each tidal elevation, which increased in strength as length of inundation decreased. To complement this seasonal study, additional experiments were undertaken, which are described in Chapter 3, to determine how anammox, denitrification and sediment metabolism responds to variations in experimental NO3- concentration and temperature. There were significant increases in rates of anammox, denitrification and sediment metabolism with temperature until 20oC when rates of anammox began to reduce. Furthermore there was significant variation in the response of all three processes to temperature in samples collected at different dates, which suggested that reduced bioavailability of organic carbon in the winter months was limiting the response to temperature. In addition to exploring how inorganic N is cycled in estuarine sediments, the ability of estuarine sediments to oxidize urea via nitrite was examined using 15N and 13C labelled substrates. Results, which are presented in Chapter 4, indicate that urea added to anaerobic sediment slurries was rapidly hydrolysed to ammonium before being oxidized via the anammox pathway.

<div>Documenting trophic relationships in aquatic ecosystems can facilitate understanding of not only system processes, but also the potential responses of food webs to stressors. Often, trophic studies assume consistent behavior and trophic roles among individuals in a population, but intraspecific diet variation, such as individual specialization, can play a critical role in food web complexity and can promote ecosystem resilience. In Lake Michigan, the introduction of invasive species (e.g., zebra mussel, Dreissena polymorpha; quagga mussel, Dreissena bugensis; round goby, Neogobius melanostomus) and reduced nutrient loading has resulted in changes in nutrient dynamics, system productivity, and community composition over the past two decades. As a result, abundances of many forage fish have declined, including alewife (Alosa pseudoharengus) which have historically supported the five dominant salmonid species of Lake Michigan (brown trout, Salmo trutta; Chinook salmon, Oncorhynchus tshawytscha; Coho salmon, Oncorhynchus kisutch; lake trout, Salvelinus namaycush; rainbow trout, Oncorhynchus mykiss). With these ecosystem changes, there is uncertainty as to the extent of how different species of salmonids will transition to alternative prey items (e.g., round goby). Common methods for examining diet patterns and trophic linkages include stomach content analysis, stable isotope ratios (e.g., δ13C and δ15N), and fatty acid composition, but these methods vary in temporal resolution and have differential biases. Furthermore, elucidating agreement of these trophic indicators and whether or not agreement is consistent across species can improve their use in future food web studies. The first research chapter of this thesis investigated the diet complexity of Lake Michigan salmonids by evaluating stomach content composition, diversity, and potential specialized consumption of different alewife lengths. Stomach contents revealed that Chinook salmon almost exclusively consumed alewife and had a lower diet diversity compared to the other four species, which consumed round goby (brown trout and lake trout), aquatic invertebrates (Coho salmon), and terrestrial invertebrates (rainbow trout) in addition to alewife. Although there were clear spatio-temporal and size-related feeding patterns for each species, much of the variation in diet composition and diet diversity was present at the individual-level. Additionally, salmonid species appeared to consume the entire size range of alewife that were available to them and individually specialized on alewife lengths. Due to their reliance on alewife, it is likely that Chinook salmon may be more negatively impacted than other salmonid species if alewife abundance continue to decline in Lake Michigan. The second research chapter assessed the agreement of multiple trophic indicators. Although we found agreement among trophic indicators across the five salmonid species using linear and logistic models, particularly between stomach contents, δ13C, and fatty acid 16:1n-7, there was significant variation in relationships across species, potentially due to variation among salmonids in specific prey items consumed (e.g., alewife and round goby) and species-specific regulation of fatty acids. Additionally, δ15N estimated from stomach contents using linear mixing models were typically greater relative to observed δ15N, which may suggest small alewife were underrepresented in stomachs of 2016 angler-caught salmonids. Lastly, stomach contents underestimated benthic resource use by rainbow trout, which may be related to biases associated with fish collection methods and stomach content analysis. Overall, the results of trophic indicator comparisons indicate that caution should be taken when generalizing trophic relationships across species and to consider biases associated with trophic indicators, especially when relying on a single diet metric.</div>

An analysis of the photoperiodic induction of flowering in Arabidopsis thaliana (L.) Heyne, Landsberg erecta ecotype, was carried out. This revealed that 4 day old seedlings, at which time the cotyledons where expanding and greening, could differentiate between a LD and a SD. At this stage the critical daylength was between 8 and 10 hours. Plants grown in daylengths of 8 hours, a short day, flowered after 50-70 days and when grown in 16 hour daylengths, a long day, flowered after 24-27 days. At 7 days seedlings required five long days to fully induce flowering and as the seedlings aged in short days they became more sensitive to interposed long days, so that by day 20 one long day was fully inductive. It was found that there were two different photomorphogenic responses shown by plants grown in short days, firstly flowering was delayed and secondly further leaves were induced. The short days delay of flowering occurred in newly germinated seedlings older than 4 days and further leaves were induced in plants older than 10 days. From light quality experiments it was concluded that both a blue light photoreceptor and phytochrome promoted flowering. The induction of flowering by phytochrome was through a HIR mode. Three of the photoreceptor mutants, hy, isolated by Koornneef et al. (1980) were used. In daylength transfer experiments all the hy mutants studied showed delay in flowering by short days and all responded to long days by flowering earlier. Both hy2 and hy3 produced far fewer leaves than Ler when grown in short days. The hy4 mutants flowered later in both long days and short days than Ler and had an increased leaf number. A scheme is proposed in which photoperiodic induction depends on the ability of the plant to sense photoperiod, the stage of development and the photobiological input. It also proposes that phyA or C and the blue light photoreceptor promote flowering whereas phyB promotes vegetative development. Two screens were set up to isolate novel photoperiodic mutants. Six mutants were isolated, from ethtylmethane sulphonate mutated seed, which all flowered earlier than Ler in SD. They were called FUN 1-6, flowering pjcoupled. Genetic analysis showed that all were non allelic and that they were recessive except .tun4 which was semi-dominant. Physiological studies showed that there were two types of mutants: firstly funl and 2 whose flowering was not significantly delayed by SD in comparison to long day treatments and flowered early in the dark; and secondly fun3-6 which all showed a delay in flowering when grown in SD. The .funl, and 2 mutants had poorly developed leaves as did fun5. The other mutants did not show any other clearly defined phenotypes. These results suggest that funl and 2 mutants are constitutive flowering mutants and the remaining mutants are transduction chain mutants.

Microbial attachment and proliferation on a surface leads to the formation of a structure known as a biofllm. In this thesis attention is directed towards the attachment of microorganisms to submerged surfaces in private swimming pools Samples were taken from two private swimming pools located in West Lancashire, England. The planktonic phase of the water was sampled using a standard fluid grab technique and the submerged surfaces (e.g. the pool lining, the steps and the water recirculation trap) were sampled using swabs and a scalpel blade to scrape the surface. Using these techniques, thirteen different bacteria (e.g. Pseudomonas spp. and Staphylococcus spp.) and one alga (Chlorella vulgaris) were isolated from the two private swimming poois. In both cases the use of a swimming pool sanitiser (Baquacil, ICI Chemicals) showed excellent control of the planktonic population. Only algae were recovered from the fluid grab sample when incubated in appropriate media. Bacteria were found to be present only on plates incubated aerobically and from areas where swabbing/scraping had taken place. No anaerobic bacteria were isolated even after a long incubation period of 120 h. On further investigation it was shown that two of the isolated species, Pseudomonas maltophilia and Ps.putida, were capable of producing extracellular polymeric substance (EPS). Production of this material has been implicated in the initial adhesion of bacteria, and further, it can act as a barrier against the diffusion of the sanitiser so that organisms exhibit higher levels of tolerance to the added swimming pooi sanitiser. Laboratory studies demonstrated that planktonic populations of one of the isolates, Pseudomonas fluorescens, attached rapidly to the surface of PVC coupons from a planktonic population thereby mimicking the in vivo situation. The shortest time investigated for attachment (3.5 h) demonstrated that up to 1x10 7 cells/cm2 were firmly adhered to the surface. Attacimient to the coupons wasalso shown to provide resistance to the swimming pool sanitiser below, at and above the recommended levels (Chapter 2), the greatest increase in resistance being two fold. Planktonic populations of bacteria were reduced to acceptable levels after incubation for only 3 hours in a dilute medium. It was also shown that the organism attached to the surface produced extracellular material. On screening of Ps.fluorescens mutants (approximately 2000, induced by transposon mutagenesis, Chapter 4) for altered sanitiser resistance, it was found that 14 of these mutants had an increased resistance to the sanitiser above that shown by the wild type cells. Polyacrylamide gel electrophoresis of total cell protein extracts of thirteen of these mutants revealed that in 11 cases, a band with a molecular weight between 52,000 and 54,000 was induced or enhanced when biocide was added to the system. If a swimming pool is not to become a potential source of infection to the bathers then attention must be paid to the submerged surface-attached population of microorganisms. Planktonic sampling will indicate that there is little microbial activity within the main body of the pool water but the techniques used only assess the quality of the bulk fluid phase of the system and not the submerged surfaces. The attachment of potentially pathogenic micro-organisms to submerged surfaces must be accepted as a nornrnl occurrence. In this state, the organisms often exhibit increased resistance to the swimming pool sanitiser. Therefore, regular cleaning (i.e. scrubbing/vacuuming) of the submerged surfaces is suggested as a part of the recommended maintenance programme for domestic swimming pools of this type.

The work of this dissertation examined the secondary metabolites of several blooms of the marine cyanobacterium Lyngbya collected in Guam and Florida with an emphasis on the isolation and structure elucidation of novel biologically active compounds. The introduction in Chapter One provides a brief history of marine natural products, a description of cyanobacteria and a summary of peptides isolated from Lyngbya collected in the Caribbean. In Chapter Two, a bioassay-guided fractionation of a Floridian collection of Lyngbya polychroa led to the isolation and structural determination of the cytotoxin desacetylmicrocolin B and the known compounds microcolins A and B. The structures were established by nuclear magnetic resonance (NMR) spectroscopic analysis. All three compounds inhibited the growth of cancer cell lines HT-29 and IMR-32 at nanomolar concentrations. Microcolins A and B were found to have little activity in the ecological assay against the marine fungus Dendryphiella salina. Chapter Three describes the isolation and structure elucidation of the glycosidic, acyl proline derivative tumonoic acid J from a sample Lyngbya sp. collected in Guam. The planar structure was determined by 1D and 2D NMR spectroscopy in conjunction with high resolution-mass spectrometry (HR-MS) data. Tumonoic acid J showed moderate activity in the ecological assay against the marine fungus D. salina. In Chapter Four, NMR-guided fractionation of a Floridian sample of Lyngbya majuscula led to the isolation of two novel cyclic peptides porpoisamides A and B. The planar structures were determined by 1D and 2D NMR spectroscopy with HR-MS data. The absolute configurations of these two compounds were defined through chiral chromatographic methods and derivatization techniques. / The porpoisamides showed only moderate activity in cytotoxicity assays against cancer cell lines HCT-116 and U2OS. Finally, Chapter Five examines a potential ecological role of compounds isolated from marine cyanobacte ria. These secondary metabolites may function as chemical defenses against competing microorganisms within marine environments. Compounds isolated from cyanobacteria were tested for anti-fungal activity against the saprophytic marine fungus D. salina. Three of the six compounds tested produced inhibitory activity at or below their natural concentration. / by Theresa Meickle. / Thesis (Ph.D.)--Florida Atlantic University, 2010. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2010. Mode of access: World Wide Web.

The objective of this thesis is the development of a unifying framework for the integration and upscaling of the fluid mechanical, ecological and biomechanical processes occurring in aquatic flows. Particular focus is on the interactions of the fluid motion with aquatic plants and sediments in aquatic systems. Appropriately formulated coupled conservation equations are developed for fluid, sediment, and plant motions. The starting points for their derivation are the continuity and momentum equations written for instantaneous local field variables, for fluid, sediment and aquatic plants. The equations of motion for fluid, sediment and plants (at the stem scale) are averaged over time and space to cope with the temporal and spatial heterogeneity of the flow field near the interfacial boundary and couple the fluid and non-fluid equations of motion. To deal with the possible discontinuity of the time-averaged fields within the averaging time, appropriate definitions and theorems for time-averaging are proposed. Time-averaging is then applied on the equations of motion for each phase to obtain the respective time-averaged equations. Time-averaged equations for the second-order velocity moments are also proposed for mobile-boundary flows. The application of consecutive time-space averaging on the continuum equations led to the development of the double-averaged equations of motion for each phase. Double-averaged continuity and momentum equations have been recently proposed for mobile-boundary flows. In this thesis, the coupled double-averaged continuity and momentum equations are proposed for the sediment material and aquatic plants at the reach scale. Double-averaged equations for the second-order velocity moments have been derived for the case of fluid and sediments. By applying the double-averaging methodology (i) the governing equations are upscaled to the scales relevant to applications, (ii) the fluid motion is rigorously coupled with the non-fluid (plants or sediments) motions, and (iii) the effect of the moving interfacial boundary is introduced explicitly in the governing averaged equations. The derived second-order hydrodynamic double-averaged equations are applied to the analysis of extensive data from Direct Numerical Simulations of turbulent open-channel flows over mobile granular beds (the simulations were performed in the Dresden Technical University by Professor J. Fröhlich's Group). The use of the double-averaged equations provides significant data reduction and assists in the data interpretation. The key physical mechanisms involved in the energy transfers between the fluid mean, form-induced and turbulent fields as well as sediment motions are identified based on the assessment of the terms in the double-averaged balances of kinetic energy.

<p> Hyperspectral and polarimetric imaging of the ocean, both below and above the water surface, has increased the interest of the Ocean Color (OC) scientific community for decades in an attempt to answer questions related to climate change, monitoring of water quality, assessment of the impact of anthropogenic activities on marine life and underwater ecosystems, detection and characterization of underwater targets. These needs are recognized by worldwide efforts devoted to acquiring accurate time series measurements in open-ocean and coastal waters by OC satellite imagery to produce reliable high-quality data records, which can be used both in support of operations and in climate studies. The reliability of satellite observations of the open-ocean and coastal zones requires these remote instruments to be regularly assessed and validated against actual in-situ measurements along with related atmospheric corrections. However, despite improvements in satellite data and retrieval algorithms, accurate retrievals in coastal waters remain challenging. </p><p> Modern hyperspectral imagers usually carry out their measurements on moving platforms, aircrafts or orbiting satellites, using push-broom scanning techniques for the acquisition of 3-D data cubes (along-track, cross-track and spectral). These data, however, may not always reflect accurately the temporal variability of measurements in a very dynamic atmosphere-ocean environment, especially in coastal areas. In recent years, new technologies have made possible the exploration of snapshot hyperspectral and polarimetric imaging of the ocean in an attempt to improve the accuracy of existing methods and exploring the pixel-by-pixel variability of the signal measured, often neglected in standard approaches. </p><p> The work presented in this thesis investigates and discusses imaging of underwater polarimetric targets in various water types and the estimation of parameters of the veiling light and the attenuation coefficients responsible for image degradation and blurring as a function of the water properties. In above water observations the effects of atmospheric aerosols and wind speed on the surface reflectance coefficients are studied along with the pixel-by-pixel variability of water-leaving radiance (<i>L_w</i>) and its relationship to water constituents for different coastal waters and atmospheric conditions, the impact of this variability on the uncertainties in above water measurements and satellite retrievals. Validation of all results has been achieved by the comparison with the comprehensive Vector Radiative Transfer simulations of the Atmosphere-Ocean System, as well as measurements by a number of other collocated radiometric and polarimetric instruments. </p><p>