Thesis (Ph. D.), Oregon Graduate Institute of Science & Technology, 1992.

Thesis (M.P.H.)--University of Michigan, 1946.

Thesis (M.P.H.)--University of Michigan, 1946.

Thesis (M.S.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains vii, 59 p. : ill. Includes abstract. Includes bibliographical references (p. 43-45).

Thesis (M.S.)--Rochester Institute of Technology, 2007. / Typescript. Includes bibliographical references (leaves 130-139).

No description available.

Th. univ.--Sciences--Dijon, 1973. / Bibliogr. p. 283-286.

Urban freshwater ponds are bodies of water that sustain a diversity of higher plants, vertebrates, invertebrates, amphibians and algae. The importance of ponds in the enhancement of diversity in urban habitats is little understood due to a lack of available knowledge of the processes and interactions that operate within the biotic components of these small aquatic ecosystems. The objectives of this study were to explore the use of algae as indicators of the biotic and abiotic challenges that occur in Sustainable Urban Drainage Systems (SUDS) and to investigate the relationships between algal population dynamics, and stress physiology and water chemistry and quality. An output of this study is the recommendation of management strategies which support the sustainable enrichment of diversity in SUDS. A longer-term consideration is to explore the potential for developing algae as potential phytoremediators in SUDS ponds. Three ponds were studied in Duloch Park, Dunfermline, Fife. Water quality and algal distribution studies indicated that excessive nutrient loads from surface water runoff, caused the ponds to become eutrophic during most of the course of the study. The ponds were particularly impacted by periodic inputs of suspended solids, road salts, and runoff from construction sites and soil erosion incidents. <i>Cladophora glomerata</i> (filamentous blanket weed) was the major algal species present in the ponds and was thus selected as the key indicator organism throughout the study. Due to the short pond retention times, planktonic microalgal populations were extremely low despite adequate nutrient supplies being available. Chlorophyll <i>a/b</i> ratios for <i>C. glomerata</i> fell below the normal chlorophyll ratio of 2.6:1 indicating excessive exposure to high irradiance. A relationship may also exist between the decline in <i>C. glomerata</i> abundance and heavy metal accumulation in the sediments, competition effects due to excessive plant growth of <i>Phragmites australis</i> and duckweed and pond turbidity. At the biochemical level the investigation of a total antioxidant assay (based on the chemical reagent ABTS) was developed for <i>C. glomerata</i> to assess sub-cellular stress responses as markers of environmental change. Fluctuations in total antioxidant activity were assigned to combinations of biotic and abiotic stress, life cycle changes and turbidity impacts within the ponds. More detailed studies of individual antioxidants (superoxide dismutase, catalase, peroxidase, glutathione reductase and glutathione-stransferase) demonstrated that <i>C. glomerata</i> had increased SOD activities. Enzymes associated with the removal of toxic H₂O₂ were detected in samples from specific locations and time frames. Depletion in protective non-protein and protein bound SH groups in certain pond samples indicated a significant level of oxidative stress possibly caused by xenobiotics. High levels of glutathione reductase activity were detected in all <i>C. glomerata</i> samples suggesting efficient enzyme recycling. It is proposed that this helps protect algal cell membranes from further oxidative damage. As sampling of algae from ponds is restricted to seasonal growth patterns and availability of algal mats an <i>in vitro</i> assay was devised to detect oxidative markers of stress ( OH) <i>in vitro</i>. This was developed using the microalga <i>Euglena gracilis</i> and comprised a non-destructive gas chromatographic technique. Experiments were constructed to simulate xenobiotic stresses <i>in vivo</i>. Cells exposed to high iron and salt concentrations at levels similar to those detected in the ponds, demonstrated high antioxidant activities, suggesting that algae and specifically <i>E. gracilis</i> may be a suitable candidate for phytoremediation programmes in SUDS. The study concludes by presenting an integrated scheme demonstrating the importance of understanding SUDS biotic components at environmental, physiological and biochemical levels. Using this scheme recommendations for improving pond management strategies are made with a view to maximising the biological potential, diversity and sustainability of SUDS ponds in the Scottish urban landscape.

The proposed methodology to most effectively manage intermittent combined sewage discharges into urban watercourses in the UK is given in the Urban Pollution Management (UPM) manual. The method is based on the use of detailed computer models of the sewerage system, wastewater treatment plant and receiving watercourse. Solving intermittent discharge problems using UPM, often requires the installation of in-sewer storage tanks. However, recent research from Germany and elsewhere (e.g. Austria and Denmark) has shown that this type of solution may be of little benefit with respect to the total emissions discharged from the entire system, where emissions from both the Combined Sewer Overflows (CSOs) and the Wastewater Treatment Plant (WTP) are considered together. This is because, in certain situations, WTP efficiency can be compromised by the prolonged periods of dilute (low nutrients and substrate) inflows which can result from the draining down of in-sewer storage tanks. The earlier research in Germany and elsewhere has been concerned with long term total emissions (annual loads) and not the problems specific to individual sites, or the benefits and/or limitations of storage with respect to acute pollution. Thus the principal objective of the research described here has been to substantiate and quantify the total emission problem by means of detailed modelling, via an evaluation of the likely storage volumes which could give rise to total emissions problems for the Perth wastewater system. Following this, a general method has been developed to investigate and resolve total emission problems related to acute pollution effects. As WTP disruption due to flow dilution can last for a prolonged period after even a single rainfall event, computational simulation times need to be long enough to represent the delay in WTP performance returning to normal operating conditions. As long term continuous simulation is usually impractical due to protracted computational times, a method referred to as the Total Emission Analysis Period (TEAP) has been developed. This will define the minimum required computational time and rainfall inputs to be used to ensure that the effect of in-sewer storage on total emissions could be modelled. Utilising the TEAP method to analyse total emissions it has been concluded that increasing volumes of storage would not be expected to create a total emission XXVI problem with respect to the Biochemical Oxygen Demand (BOD). Consequently, it was concluded that the best storage volume with respect to BOD was the minimum volume which would allow compliance with receiving water quality standards. No direct comparison could be made with the conclusion derived from the German research due to the long term nature of their analysis, however, it would appear from an interpretation of their results, that similar findings were obtained. With respect to ammonia, it was found that increases in total emissions can occur as, ammonia concentrations, unlike BOD, do not increase at the start of a storm due to first foul flush effects. Consequently, any increased emissions from the WTP would not be offset via a reduced CSO spill load. It was also found, however, that increasing volumes of storage would not be expected to exacerbate acute pollution problems within a receiving watercourse and that both large and small storage volumes had the potential to give rise to very similar degrees of WTP disruption. This was due to the way in which different hydraulic loading conditions (caused by the different volumes of storage) affected the bacterial concentrations in the reactor. The conclusion that storage would not provide a significant benefit for ammonia total emissions was supported by the Austrian and Danish research.

No description available.