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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
461

Quantifying changes in ecological function of headwater catchments following large-scale surface mining in southern West Virginia

Gingerich, Gretchen Anne. January 1900 (has links)
Thesis (M.S.)--West Virginia University, 2009. / Title from document title page. Document formatted into pages; contains xvii, 195 p. : ill. (some col.), col. map. Includes abstract. Includes bibliographical references (p. 58-90).
462

Aquatic leisure & training centre at Stanley

謝啓倫, Tse, Kai-lun, Alan. January 1999 (has links)
published_or_final_version / Architecture / Master / Master of Architecture
463

Host Affiliations and Geographic Distributions of Fungal Endophytes Inhabiting Aquatic Plants in Northern Arizona, USA

Sandberg, Dustin Cody January 2013 (has links)
Fungal communities of aquatic ecosystems are understudied, leaving major gaps in estimating global fungal biodiversity. In particular, little is known regarding the distinctiveness of (1) aquatic endophytes vs. those in terrestrial plants, and (2) waterborne fungi vs. those inhabiting aquatic plants or sediments. I assessed the diversity, composition, host affiliations, and geographic structure of culturable endophytes associated with aquatic angiosperms in reservoirs in northern Arizona, and their distinctiveness relative to waterborne- and sediment fungi. Endophytes were low in abundance yet extremely diverse. Communities differed significantly in composition among reservoirs and tissues. Aquatic endophytes were largely distinct from those in terrestrial plants, and from those in water and sediment, but did not demonstrate host specificity. This work reveals the uncommon diversity and distinctiveness of endophytes in aquatic plants, and provides a first quantitative estimation of endophytic associations in diverse, ecologically important, and economically relevant aquatic plants.
464

The Vancouver Aquatic Centre: in-between phenomenon : water and land

Cheung, Lisa 05 1900 (has links)
A modern large recreational hall may hardly recognize a sense of human scale nor provide users the architectural meaning corresponding to the activities it accommodates. The experimental project of renovating the Vancouver Aquatic Center attempts to reinstate the relationship between the body, water and architecture. There exist certain sequence and pattern in participating various leisure/fitness activities which require mental and physical preparation. I focus on accentuating the transitional experiences at different stages of taking part swimming, diving, and hot baths by creating spaces to allow mental readiness for activities and contemplation of experience. Thus, I explore the perception of edges by marking of different threshold, making it subtle or bringing it out into presence. This practice requires much envision of walking through the building and anticipation of how space to be used which corresponds to my study of history of bathing and questions of perception. In order to reintroduce the social value of bathing which exists in Japanese bath and the like, I expand the facilities program parallel to the concept of Roman Thermae where people can meet and interact. Therefore, the proposed new aquatic centre seeks to enhance social and visual communication between the surrounding environment and the building, between users outside and inside, between different activities within the building. Moreover, initiated by the study of phenomenological architecture, this project revolves around the idea of intriguing memories and emotions through associative and tactile experience by the use of materials, spatial configuration, lighting, transparency and the placement of apertures to capture views. I try to provide diversified experience with different forms of water, steam, hot/cold temperatures, brightness/darkness, hard/soft land, submerge/emerge, clear/opaque and other perception of space. The ultimate goal of this experiment is to provide users the meanings of the architectural form, space, material and order, yet as well give potential to allow the users' own interpretations.
465

Towards a relevant architecture : an international rowing and canoeing regatta centre for KwaZulu-Natal, South Africa.

Howie, Craig John. January 2010 (has links)
2008 was a year which highlighted how far South Africa has fallen behind the rest of the world in the international Olympic sporting arena. High hopes for the Olympic Games in Beijing ended in a lower-than expected medal tally that sparked great debate in South African society. The reasons for this phenomenon are numerous and complex and it is not the intention of this dissertation to investigate all these concerns. However, what is of an architectural concern is the inadequate and often sub-standard sporting facilities which athletes in South Africa, in non-mainstream sporting codes, have to contend with. The challenge for architects in this regard is to design buildings for these sports, that are both adequate and of a suitable standard, while remaining relevant to their context. This to promote professionalism and inspire athletes to succeed through the creation of high quality, world-class facilities for competition, training and preparation. Rowing, canoeing and kayaking are highly competitive and technologically advanced Olympic sports. Many South African athletes compete in these disciplines and have enjoyed limited international success. Unfortunately, as there are currently no international regatta centres in Southern Africa, these same athletes have to travel abroad to compete and train at such facilities. South African athletes and the sports of rowing, canoeing and kayaking would thus benefit greatly from having access to locally based regatta facilities. KwaZulu-Natal has a proud sporting heritage and is synonymous with water sports as a result of its favourable climate and geographic location. This coupled with various other established sporting infrastructure, makes it the ideal Province for hosting major sporting events. Both Durban as a city and KwaZulu-Natal as a Province, have an impressive track record for hosting large sporting events. The Province has future aspirations of hosting major sporting events including the Commonwealth Games and the Olympics Games, with Durban soon hoping to be bidding to host the 2020 Summer Olympics. To host such events will require the design of many specialised sporting facilities for the city and will include the need for an international regatta centre. In my opinion, the best site for such a centre in KwaZulu-Natal is at Camps Drift in Pietermaritzburg. The requirements for an international regatta centre are both highly technical and very specific as set out by the respective world sporting governing bodies. These requirements need to be strictly adhered to in order for the Centre to be considered to be of an internationalstandard. The challenge will be to design architecture that is functional in achieving these set criteria while, remaining relevant to the social, economic and environmental context of its design. Thus the purpose of this research document is to determine a relevant architecture for the design of an International Regatta Centre for KwaZulu-Natal. / Thesis (M.Arch.)-University of KwaZulu-Natal, Durban, 2010.
466

Level of UV-B Radiation Influences the Effects of Glyphosate-Based Herbicide on Fitness of the Spotted Salamander

Levis, Nicholas A. 01 May 2014 (has links)
Numerous causes have been implicated in contributing to amphibian population declines since the 1980's, with habitat modification, ultraviolet radiation (UV-B) and environmental contaminants (such as glyphosate-based herbicide) being among the most common. This study identifies the effects of a generic glyphosate-based herbicide (GLY- 4 Plus) on mortality, immune function, body condition, and morphological plasticity of larvae of the spotted salamander (Ambystoma maculatum) under conditions that reflect open and closed canopy light regimes. Larval salamander responses to glyphosate-based herbicide varied depending on UV-B conditions. In general, it appears that an open canopy (i.e. greater UV-B exposure) may confer fitness benefits. In the presence of herbicide, survival was higher in an open canopy UV-B regime and pooled open canopy survival was higher than that of closed canopy treatments. In the absence of herbicide, body condition and immune function were positively related with amount of UV-B. Finally, herbicide presence appeared to affect morphology under low UV-B conditions. UV-induced breakdown of surfactant or a complex interaction between temperature stratification and trophic relations is potentially responsible for the observed patterns in survival and body condition. However, the mechanistic underpinnings of improved immune function and morphological differences are less clear. As deforestation is likely to continue, amphibians may find themselves in ponds with increasingly open canopies. Combined with the knowledge that some amphibians can become locally adapted to UV exposure and develop pesticide tolerance, the probability of surviving exposure to this herbicide may be elevated in open canopy ponds. These results emphasize the complexity of natural systems and the importance of including multiple factors in experiments.
467

Riparian Ecosystem Response to Hemlock Woolly Adelgid (<i>Adelges tsugae</i>) Induced Eastern Hemlock (<i>Tsuga canadensis</i>) Mortality in the Great Smoky Mountains National Park, USA

Huddleston, Misty Dawn 01 December 2011 (has links)
An invasive insect, hemlock woolly adelgid (HWA), has initiated widespread hemlock decline and mortality in the Great Smoky Mountains National Park (GSMNP). Riparian hemlock mortality impacts on vegetative and aquatic systems of first-order, headwater streams were evaluated. Reference sites for this study were representative of the best available conditions within the GSMNP, with initial stages of HWA presence. Impacted sites were defined as areas with over 90 percent hemlock mortality. Impacted streams had decreased canopy coverage and increased light availability. Residual red maple, yellow birch, and sweet birch capitalized on the loss of hemlock, with increases in relative basal area and species importance values. Rosebay rhododendron responded with increased density and height at impacted sites, thereby preventing woody regeneration. Since long-term regeneration and post-mortality canopy recruitment are limited, alterations of vegetative composition and structure in the stream riparian zone are expected. A seasonal assessment (Sept. 2009 – March 2010) of aquatic impacts revealed increased diurnal variation in stream temperature and exhibited cooler temperatures during the colder months than reference streams. Impacted streams exhibited greater amounts and larger size classes of large woody debris (LWD). Higher concentrations for several nutrients, including silicon, sodium, potassium, magnesium, chlorine, and copper were detected in impacted streams than detected in reference streams. Impacted streams were characterized by higher pH and increased acid neutralization capacity, while reference streams exhibited nitrate concentrations three times higher than impacted stream concentrations. Reference streams were experiencing the initial stage of HWA-induced defoliations, increasing stream nitrate concentrations, while impacted sites had levels suggesting nitrate concentrations have returned to pre-infestation levels. A seasonal assessment of macroinvertebrates found species diversity, abundance, and taxa richness were not affected by hemlock mortality. Impacted streams had a lower density of Chironomidae and Ephemeroptera when compared to reference streams, while Pleuroceridae snails were virtually eliminated at impacted stream sites. Reference streams were dominated by the collector/filter functional feeding group (FFG), while impacted streams were dominated by the scraper FFG. Hemlock mortality induced by the presence of HWA has resulted in short-term impacts to vegetative and aquatic dynamics in stream riparian areas of the Great Smoky Mountain National Park.
468

Carbon acquisition in variable environments: aquatic plants of the River Murray, Australia.

Barrett, Melissa S. January 2008 (has links)
This thesis considers the implications of changes in the supply of resources for photosynthesis, with regard for modes of carbon acquisition employed by aquatic plants of the River Murray. Carbon supplies are inherently more variable for aquatic plants than for those in terrestrial environments, and variations are intensified for plants in semi-arid regions, where water may be limiting. In changeable environments the most successful species are likely to be those with flexible carbon-uptake mechanisms, able to accommodate variations in the supply of resources. Studies were made of plants associated with wetland habitats of the Murray, including Crassula helmsii, Potamogeton tricarinatus, P. crispus and Vallisneria americana. The aim was to elucidate the mechanisms of carbon uptake and assimilation employed, and to determine how flexibility in carbon uptake and/or assimilation physiology affect survival and distribution. Stable carbon isotopes were used to explore the dynamics of carbon uptake and assimilation, and fluorescence was used to identify pathways and photosynthetic capacity. The studies suggest that physiological flexibility is adaptive survival in changeable environments, but probably does not enhance the spread or dominance of these species. V. americana is a known bicarbonate-user, and it is shown here that it uses the Crassulacean Acid Metabolism (CAM) photosynthetic pathway under specific conditions (high light intensity near the leaf tips) concurrently with HCO[subscript]3 - uptake, while leaves deeper in the water continue to use the C[subscript]3 pathway, with CO₂ as the main carbon source. However, V. americana does not use CAM when under stress, such as exposure to high light and temperature. The diversity of carbon uptake and assimilation mechanisms in this species may explain its competitive ability in habitats associated with the Murray. In this way it is able to maximise use of light throughout the water column. In shallow, warm water, where leaves are parallel to the surface, CAM ability is likely to be induced along the length of the leaf, allowing maximal use of carbon and light. The amphibious C. helmsii is shown to use CAM on submergence, even where water levels fluctuate within 24 hours. This allows continued photosynthesis in habitats where level fluctuations prevent access to atmospheric CO₂. It appears that stable conditions are most favourable for growth and dispersal, and that the spread of C. helmsii is mainly by the aerial form. Carbon uptake by P. tricarinatus under field conditions is compared with that of P. crispus to demonstrate differences in productivity associated with aqueous bicarbonate and atmospheric CO₂ use. P. tricarinatus uses HCO[subscript]3 - uptake to promote growth toward the surface, so that CO₂ can be accessed by floating leaves. Atmospheric contact provides access to light and removes the limitation of aqueous diffusive resistance to CO₂, thereby increasing photosynthetic capacity above that provided by submerged leaves. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1320380 / Thesis (Ph.D) -- University of Adelaide, School of Earth and Environmental Sciences, 2008
469

The effects of stream productivity on aquatic-terrestrial linkages

Burdon, Francis John January 2004 (has links)
The potential relationship between riparian arachnids and aquatic insect productivity was assessed in forest streams throughout the central South Island of New Zealand. Initially, a survey was conducted of thirty seven, first-third order forest streams. Streams were selected to represent a range of benthic invertebrate standing crops (as a surrogate measure of "productivity") from Banks Peninsula streams with relatively high benthic invertebrate densities to acid mine drainage streams near Reefton that were almost devoid of aquatic life. At each site benthic invertebrate densities and biomass were measured in riffle habitats and adjacent gravel bars were sampled for terrestrial invertebrates. At a sub-set of 16 sites, a 20 metre longitudinal web-building spider survey was conducted along each bank of the stream. As an additional component, a 20 metre transect starting at the stream margin and running perpendicularly into the forest was used to survey the density of web-building spiders with increasing distance from the stream. Results from the survey of in-situ stream insect biomass and gravel bar invertebrates showed a strong relationship between aquatic insect biomass and the biomass of riparian arachnids (R2 = 0.42, P < 0.001) having accounted for potentially confounding factors such as stream size, elevation, substrate and disturbance. The 20 metre longitudinal survey showed that streams with the highest in-situ insect biomass had significantly higher densities of web-building spiders along their banks (R2 = 0.28, P < 0.05), having accounted for potential confounding variables of elevation, habitat architecture and stream and channel width. The stream to forest survey showed a strong exponential decay in web-building spider densities with increasing distance from the stream (R2 = 0.96, P < 0.0001). Regardless of stream productivity web-building spiders were most abundant at the stream margins and rapidly declined to very low densities 20 metres from the stream. In order to further test the relationship between riparian web-building spider densities and stream insect productivity, a stream fertilization experiment was conducted on six first-second order streams in the Maimai experimental catchment, Reefton. Three streams were enriched by the addition of a fertiliser solution mainly consisting of sodium nitrate for seven months, and the other three streams were used as controls. Water chemistry, benthic invertebrate communities, emerging aquatic adults, and the densities of web-building spiders along the stream corridor and in the forest were monitored in three seasons (spring, summer and autumn) over the course of the nutrient-addition. By the end of the experiment, conductivity was significantly higher in nutrient-addition streams than in the control streams (F = 80.5, P < 0.001), but chlorophyll concentrations showed no significant differences between treatments. Both benthic mayfly densities (F = 6.15, P < 0.05) and the biomass of adult aquatic dipterans (Chironomidae, Simuliidae) (F = 9.25, P < 0.01) were significantly higher in nutrient-addition streams in the last sampling round. Spiders recorded from intercept traps indicated that by the end of the experiment spider activity was significantly higher within 2.5 metres of the nutrient-addition streams (F = 5.70, P < 0.01). However, seasonal densities of web-building spiders along the stream margin and in the forest decreased with no significant differences observed between nutrient-addition and control streams. The results from these studies indicate that adult insects emerging from streams represent an important source of prey that could influence the biomass and abundance of riparian arachnids. Additionally, the results imply that stream productivity and size could mediate the strength of the interaction between riparian and stream habitats. Moreover, feedback mechanisms present in both systems could have implications for such interactions. The elevated densities of web-building spiders observed at the stream margin led to the proposal of the "Highway Robber" hypothesis. This hypothesis suggests that such higher densities of spiders are the result of increased insect activity along the stream corridor: the emergence of adult aquatic insects was predicted to vary less over temporal and spatial scales than that of terrestrial insects due to the poorly synchronized life histories in many New Zealand stream insects. I conclude by suggesting that there are numerous anthropocentric perturbations such as loss of heterogeneity, introduced species, pollution and habitat degradation that could undermine and decouple the intimate linkages between aquatic and terrestrial ecosystems.
470

Chemical speciation of silver(I) in freshwater /

Adams, Nicholas. January 1999 (has links)
Thesis (Ph.D. ) -- McMaster University, 1999. / Includes bibliographical references [p.47-55]. Also available via World Wide Web.

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