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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.
381

The use of small ephemeral wetlands and streams by amphibians in the mixedwood forest of boreal Alberta

Okonkwo, Godwin 06 1900 (has links)
Identifying amphibian habitats within a landscape provides a tool for managing their populations. I identified if and how amphibians used small ephemeral wetlands (≤ 0.1ha) and streams within the mixedwood forest area managed by Daishowa Marubeni International Ltd. near Peace River, north-western Alberta. Twenty-seven wetlands and their riparian zones were sampled for all life stages of amphibians in 2008 using timed visual encounter surveys. The riparian zones of 11 small streams were sampled with pitfall traps within 120 m of their beds from 2006 to 2008. Habitat features were also measured. Lithobates sylvaticus, Anaxyrus boreas and Pseudacris maculata used small ephemeral wetlands and the riparian zones of ephemeral, intermittent and permanent streams at different life stages. Water temperature and canopy cover influenced amphibian presence and abundance in wetlands. Coniferous and deciduous tree density were associated with L. sylvaticus abundance at the stream sites. I conclude that small waterbodies are amphibian habitats in the mixedwood forest of boreal Alberta. / Ecology
382

the non-market valuation of wetland restoration and retention in Manitoba

Pattison, John Karl 11 1900 (has links)
Wetland loss is a concern in Canada, with significant loss in urban and agricultural areas. Due to their provision of ecological goods and services - water quality improvement, carbon sequestration, flood and erosion control and biodiversity - wetlands are an important natural resource to conserve. A stated preference CVM survey was designed to estimate the non-market values of wetland in the prairie pothole region of Manitoba. This included information on benefits and costs associated with wetland restoration, a referendum portion and a debriefing section. A rigorous design procedure was followed that included several public focus groups and pre-tests. Results from 1,980 individuals indicate that respondents are willing to pay to retain and restore wetlands. Conservative willingness to pay estimates placed between $290 (retention) and $360 (full restoration) per household per year. Aggregated to the entire province over a five year period, this increases to approximately $600 and $730 million, respectively. / Agricultural and Resource Economics
383

Fate of fluorinated organic pollutants in aquatic plant systems: studies with lemnaceae and lemnaceae tissue cultures

Reinhold, Dawn Marie 24 October 2007 (has links)
Aquatic plants of the family Lemnaceae (e.g., duckweed) actively uptake, metabolize, and sequester pollutants in natural and engineered wetland systems. Numerous interrelated processes contribute to pollutant removal in wetlands; of these processes, interactions between organic pollutants and aquatic plants may be least understood. Research focused on (1) understanding parameters that affected uptake of fluorinated organic pollutants by Lemnaceae, (2) identifying plant processes involved in removal of wastewater-associated organic pollutants by Lemnaceae, and (3) assessing use of Lemnaceae callus cultures in understanding toxicity and metabolism of fluorinated organic pollutants by Lemnaceae. Through active plant uptake, Lemna minor rapidly removed 13 fluorinated phenols, with pseudo-first order rate constants of 0.20±0.04 d-1 to 0.84±0.07 d-1. Uptake rates depended on substituent type (i.e., trifluoromethyl- vs. fluoro-) and position, with slowest removal rates for di-ortho-substituted fluorophenols. Uptake rates decreased with increasing concentrations of fluorinated phenols; assessments of inhibition of plant oxygen production in conjugation with concentration studies indicated that concentration affected uptake rates even when Lemnaceae was not inhibited. Additionally, temperature dependencies of fluorinated phenol uptake by Lemnaceae were well represented by Arrhenius relationships; however, effects of temperature on plant activity were also observed in trends of uptake rates with temperature. Increasing uptake with decreasing concentration and increasing temperature, in addition to effects of plant inhibition, plant activity, and sorption on uptake, strongly emphasized the importance of plant metabolism in uptake of fluorinated phenols by Lemnaceae. Active plant uptake of wastewater-associated organic pollutants affected fate of fluoxetine, triclosan, and 2,4-dichlorophenoxyacetic acid, while passive plant removal processes contributed to fate of four of six wastewater derived organic pollutants. Consequently, plant-associated processes were important components of fate for over 50% of experimental wastewater-associated organic pollutants. Furthermore, assessments with Lemnaceae callus cultures indicated that callus cultures were generally more susceptible to inhibitory responses to fluorinated phenols than were Lemnaceae plants; however, metabolism of 3-trifluormethylphenol in Lemnaceae callus cultures and plants was similar, indicating that callus cultures may be valuable in plant metabolism studies. Research advances understanding of fate of organic pollutants in wetland systems, and thus has important implications for water quality, ecosystem health, and human health.
384

Reedbeds for the treatment of greywater as an application of ecological sanitation in rural Costa Rica, Central America

S.Dallas@murdoch.edu.au, Stewart Dallas January 2005 (has links)
The widespread practice in Latin America of separating greywater from blackwater at the domestic level lends itself to the application of Ecological Sanitation, or Ecosan. In this research simple, low-cost subsurface flow wetlands, or reedbeds, were investigated not only for their potential in treating the greywater component but also to evaluate their acceptance as an appropriate Ecosan technology in rural Central America. The hypothesis for this thesis is that Ecological Sanitation, namely via reedbeds for the treatment of greywater can improve sanitation in rural Central America. The first aim of this research determined that untreated greywater was having a significant negative impact on the water quality of the local streams of Monteverde in Costa Rica (the site of this research) and that the associated public health risks will continue to increase in line with population growth. Local residents expressed strong dissatisfaction with the current situation and were supportive of any means to improve it. The second aim of this research was to determine if reedbeds designed according to the principles of Ecosan could provide a healthier, affordable and more sustainable sanitation alternative suitable for rural areas. As a result five case study reedbed systems were designed and installed. All these reedbeds made use of locally available materials and incorporated low-maintenance design features, and research with a local plant species determined a robust macrophyte suitable for use in these systems. The ability of low-cost reedbed systems to successfully treat greywater was demonstrated. The Costa Rican guidelines for wastewater reuse were found to be overly restrictive in regards to fecal coliform limits (<1,000cfu/100mL) and may inhibit the wider uptake of reedbed systems if enforced. Despite this the uptake of the reedbed technology was strong and more than ten systems were installed in Costa Rica as a result of this research. An innovative environmental services contract, the first of its kind in Costa Rica, was developed to ensure on going funding for operation and maintenance of a four-household reedbed system. The third aim was to specifically investigate the use of waste plastic (PET) bottle segments as an alternative media in reedbeds to conventional crushed rock, or gravel. Twelve mini-reedbeds, or cells, incorporating PET media and plants as the two variables, were monitored through wet and dry seasons. This experiment demonstrated that reedbeds incorporating PET segments were able to achieve comparable removal of fecal coliform and BOD when compared to conventional media reedbeds, and at a significantly reduced cost. The local plant species Coix lacryma-jobi enhanced the performance of all reedbeds, most notably in the PET-based reedbeds, which was attributed to the considerably greater root biomass achieved in these systems as compared to conventional media systems. This research has demonstrated that reedbeds incorporating simple, low-maintenance design features are able to provide an affordable and appropriate technology for the treatment of greywater in rural Latin America.
385

Mosquitoes as a part of wetland biodiversity /

Schäfer, Martina, January 2004 (has links)
Diss. (sammanfattning) Uppsala : Univ., 2004. / Härtill 5 uppsatser.
386

Mechanisms of phosphorus removal by constructed wetland systems /

Ryan, Gregory Lawrence. January 2003 (has links)
Thesis (PhD) -- University of Western Sydney, 2003. / "Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy at the University of Western Sydney, Hawkesbury." "April 2003" Bibliography: leaves 287 - 302.
387

The ecotourism potential of the Barber Inlet Wetlands, South Australia /

Higginson, Gareth Edward. January 2000 (has links) (PDF)
Thesis (M.Env.St.)--University of Adelaide, Mawson Graduate Centre for Environmental Studies, 2000. / Bibliography: leaves 127-134.
388

An investigation of the impacts of wetlands, wetland mitigation banks, and open spaces on nearby property values

Beal, Mary, January 1900 (has links)
Thesis (Ph. D.)--Florida State University, 2007. / Advisor: Keith Ihlanfeldt, Florida State University, College of Social Sciences, Dept. of Economics. Includes bibliographical references.
389

Ultraviolet disinfection system for constructed wetlands /

Ly, Jong Chan. January 1900 (has links)
Thesis (M.S.)--Humboldt State University, 2008. / Includes bibliographical references (leaves 40-44). Also available via Humboldt Digital Scholar.
390

The potential impact on mosquito larvae by threespine stickleback (Gasterosteus aculeatus) and mosquitofish (Gambusia affinis) in four constructed wetlands /

Simpson, Nicholas P. January 1900 (has links)
Thesis (M.S.)--Humboldt State University, 2008. / Includes bibliographical references (leaves 63-68). Also available via Humboldt Digital Scholar.

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