The objective of this study was to develop novel techniques for on-line sample pre-treatment for use with atomic spectroscopy. Preconcentration of the analytes using either complexation of the analyte(s) on an analytical column or by in-situ (in atomiser) trapping on a pre-coated graphite tube has been used. The samples were manipulated using flow injection analysis and detection achieved in most cases by ETAAS. All aspects of the study are supported by reference to the literature. Using the above approach, a new method has been developed to determine mercury in environmental (sediment) and biological (tuna fish) samples. This approach successfully achieved a sample throughput of 20-30 sample per hour, with a method detection limit of 0.2 ng g*^ (3a) and a precision of less than 10% at the 0.1 ug g"^ level. An interference study was conducted and seven elements ( As\, Cd", Cu", Ni", Pb". Sb'' and Se"") shown to give less than a 5% interference when the interferent concentration was 2 orders of magnitude greater than the Hg. Silver showed a 9% interference when one order of magnitude greater than the Hg. The technique of "in atomiser trapping" was applied to the determination of As, Bi, Sb and Se, in lake water samples. The hydrides were sequestrated upon an Ir coated graphite tube and the instrumental and chemical parameters optimised for multi-element determinations. Iridium has been identified as the best trapping material (coating) for multi-element determinations. The final method gave detection limits of 0.82, 0.04, 0,26 and 0.29 ug 1'^ (500 ul sample loop) for As, Bi, Sb and Se respectively. A characteristic mass of 177 pg for As, 91 pg for Bi, 107 pg for Sb and 90 pg for Se was achieved. Good agreement was obtained with certified and standard reference materials and the method was successfully applied to the determination of As, Bi, Sb and Se in lake water samples. Six elements (Cd, Cu, Fe, Mn, Ni and Pb) were selected for determination in seawater samples by multi-element on-line column preconcentration. The sample stream was mixed on-line with a buffered solution of diethylammonium dithiocarbamate (DDDC). and the metal-DDC complex retained upon a Cie RP silica column. Ethanol was then used to elute the metals from the column directly into the graphite tube. Disappointing results, were obtained due to interference problems, and although more work is required before this approach may be routinely used, it is shown to have potential for the future. Overall, this study has shown that novel methods employing flow injection methodologies for separation and preconcentration are a viable way to prepare environmental sample for analysis by ETAAS. Further it has demonstrated that multi-element analysis is possible for low levels of analyte despite the presence of troublesome matrices, although further work is required to achieve the ultimate goal of a universal method suitable for all analytes irrespective of the sample type.

The geochemical, biogeochemical, and hydrologic controls on the stream chemical composition of alpine watersheds were investigated using the Alpine Hydrochemical Model (AHM). This model was successfully applied to the Emerald Lake watershed and two nearby watersheds as well as two watersheds in the Rocky Mountains, Andrews Creek and the Green Lakes Valley. The results reveal that snowmelt in alpine watersheds must come into contact with either soil, sub-talus, or reactive bedrock surfaces to explain the geochemistry observed in alpine lakes and streams. These materials do not differ geochemically but they do differ in their influence on the amount of mineral nitrogen observed in alpine lakes and streams. Improvements to the carbon-nitrogen dynamics portion of the ARM indicate that the Emerald Lake watershed is nearing nitrogen saturation. A robust multi-criteria sensitivity analysis technique was used to determine what processes were important for simulating the observed stream chemical composition. This sensitivity analysis revealed that concentration and mass flux representations of stream chemical composition contain different information about the watershed. The sensitivity analysis results were used to guide a multi-criteria parameter estimation algorithm. The results showed that stream chemical data is useful in discerning the importance of different processes and the role they play in determining stream chemical composition.

No description available.

This research was developed as one of the first studies to investigate riverine litter problems. Baseline assessment methods were formulated to define the scope and nature of this pollution form. Assessments were carried out in three catchments; the Taff East Lyn and Avill. The Taffwas found to be atypical regarding the extent of the litter. In all catchments plastic sheeting formed the principal litter component. The study also included an examination of the factors influencing the sources, pathways and sinks riverine litter pollution. These factors were drawn together through the development of a research model. Assessments of two quantifiable sources, sewage inputs through Storm Water Overflows (SWOs) and fly-tipping wastes, were undertaken. Greatest inputs of sewage-derived solids were introduced to the river through malfunctioning SWOs, the most numerous single component being sanitary towels. Whilst sewage-derived material constituted approximately 23% of all items on the River Taff large quantities of waste, especially plastic sheeting, originated from fly-tipping sites. Mobility of litter once introduced to the system was greatly dependent on river flow regimes. Some litter types, e.g. plastic sheeting, were more mobile than others and tended, after floods, to be stranded on vegetation. Due to its high profile within the catchments and expected longevity, plastic sheeting was chosen for river-bank degradation trials. Results indicated that photodegradation occurred within samples, but only in the initial exposure period and that any further breakdown was likely to result from physical abrasion. Marine areas were considered to be potential sinks for riverine litter, especially its more mobile components. An alternative sink for certain litter types such as cloth might be incorporation into the river-bank due to an ability to aggregate soil/sediment particles.

This study set out to investigate the processes that lead to emitter fouling in wastewater reuse systems. The susceptibilities of several emitter designs to clogging were compared and the role of phytoplankton in the clogging process and in the development of algal mats was investigated. Emitter design was found to be an important factor controlling the degree of clogging. Those designs that operated most efficiently used a long-path narrow labyrinth to control emitter output and encourage turbulent flow. Simpler designs that controlled flow by small sponge inserts or by stitched tubing were found to be unsuitable for use with treated wastewaters. The most common cause of clogging was found to be sand particles in the size range 360 urn to 1080 urn, trapped within the narrow channels of emitters. The sand contaminated the entire irrigation system from the potable water supply in July 1987, before a screen filter was installed in the water supply line. Emitter clogging under these circumstances was a problem, to varying degrees, for all emitter designs and for all water qualities. Emitters supplied with WSP effluent generally clogged to a greater degree than those supplied with potable water and the principal cause of clogging was shown to be sand particles. However, no statistically significant difference was recorded in the discharge characteristics of the most efficient emitter design between different water qualities. Thorough cleaning of the irrigation laterals in 1987 and replacement of emitters in 1988 failed to eradicate the sand contamination problem. Examination of clogged emitters by electron microscopy showed that organic material encased the sand particles in clogged emitters from laterals supplied with WSP effluent, thereby sealing the water channel. This mass was shown to be comprised of dead microalgae and invertebrate animals such as Daphnia spp. on which bacteria developed. Microalgae did not multiply in the dark environment of the emitter interiors. External algal mats were detected on less than 5 percent all emitters supplied with WSP effluent and were absent on all emitters supplied with potable water. Emitter C, which was the design that presented the largest wetted surface to sunlight, developed the greatest number of mats and covering these emitters with black polythene prevented mat development. The mats were shown to comprise of predominantly filamentous cyanobacteria (Oscil/atoria spp. and Lyngbya spp.) and filamentous green algae (Microcystis spp.). Although these organisms were also detected on the walls of the maturation pond, they were not detected in grab samples of pond effluent which contained predominantly planktonic algal genera such as Euglena spp. and Chlorella spp. Short decaying filaments of Oscillatoria spp. were, however, detected within the irrigation laterals and on the surfaces of sand particles within clogged emitters and no degree of filtration would guarantee their complete removal from the pond effluent. It was hypothesised that their development on the outer surfaces of emitters was a result of colonization of a well-illuminated, wet and nutrient-rich environment and that the source of the inoculum was as likely to be the soil as to be the maturation pond. Studies of greenhouse irrigation systems in the UK revealed that algal mats were a consequence of applying inorganic nutrients to the crop in the irrigation water: their development can be prevented in greenhouses by chlorination of the water supply. It was concluded that clogging results from a combination of physical, chemical and biological factors. Sand particles can be efficiently removed from the water supply by incorporating a simple screen filter, with a mesh size of at least 120, that allows microalgae to pass through the system to the soil. Clogging by sand particles was exacerbated by chemical precipitation of calcium carbonate and by the development of a organic material over the surface of the sand particles in emitters supplied with pond effluent. Biological growth alone was not shown to cause emitter clogging. It was also shown that the development of algal mats over the outer surface of emitters supplied with pond effluent were not a result of an accumulation of pond algae at this point but represented an opportunistic colonization of a well illuminated nutrient-rich environment by microorganisms from the atmosphere and/or soil. Algal mats had no adverse effect on the operation of emitters in WSP reuse irrigation.

published_or_final_version / Civil Engineering / Master / Master of Philosophy

No description available.

A case study of dry well recharge / Research Project Technical Completion Report (A-114-ARIZ) / Prepared for the U.S. Department of Interior / September 1983.

No description available.

No description available.