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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.
81

Sweden’s financial support system for implementation of wetlands in agriculture : Key enabling and disabling factors

Svensson, Charlott January 2015 (has links)
The main objective of this study, conducted by the request of the Swedish Environmental Research Institute’s (IVL) office in Beijing, was to analyse and draw lessons from Sweden’s financial support system regarding the implementation of wetlands in agriculture. Of special interest were the factors that motivate or does not motivate farmers to implement wetlands on their lands. The study was based mainly on a literature analysis, with elements of a more participatory kind, such as interviews and questionnaires with professionals from governmental-and guidance agencies. The study was carried out in February to March 2015. According to the result, key factors for successful wetland projects are: 1. Put more effort into developing long-term relationships with farmers, 2. Provide more information regarding the efficiency of the wetland to the landowner, 3. Create more flexible contracts for farmers, 4. Establish a nutrient “credit” system. Keywords: farmers willingness, financial support system, Rural Development Programme, support grants wetlands, agri-environmental measure
82

Factors Affecting Soil Total Mercury, Carbon and Nitrogen Distributions in Seasonal Pond Basins within a Northern Hardwood Forest in Minnesota, USA

Boche, Mikayla Jane January 2016 (has links)
Forests are sites for mercury deposition, where accumulation in aquatic environments can occur. Soil total mercury (THg), C and N to 15 cm were studied in ten seasonal pond basins in a northern hardwood forest (Minnesota, USA). Pools and concentrations of THg were lower in uplands than in ponds, indicating downslope transport or differential deposition. In uplands, THg concentrations were the same in 0-2 and 2-5 cm depths and then decreased, whereas density peaked in 2-5 cm, highlighting the importance of bulk density on mass. Carbon and N trends were similar to THg. Apart from pond centers, strong positive relationships between THg and C were observed. Upland slope length, graminoid cover, basin area and tree height accounted for over half of THg variance at pond edge. Understanding the distribution, trends and contributing factors of soil THg can further efforts toward immobilization and sequestration, thus minimizing the potential for bioaccumulation. / United States Forest Service / North Dakota State University
83

Bioconcentration and Morphological Effects of Triclosan on Three Species of Wetland Plants

Smith, Caleb M. 05 1900 (has links)
Triclosan (TCS) is an antimicrobial compound found in several types of common household products. After being washed down the drain, TCS will then end up in the local watershed. Although numerous studies have been conducted to evaluate the fate and effects of TCS in aquatic environments, there have been no studies evaluating the role arbuscular mycorrhizal fungi (AM) play in a plants response to TCS exposure. Three species of wetland plants native North Texas were inoculated with AM spores and exposed to 0, 0.4 g/L and 4.0 g/L TCS concentrations. Root morphology of E. prostrata and S. herbacea showed AM and exposure responses. S. herbacea produced the greatest amounts biomass and TCS bioaccumulation, in all but one treatment. It also displayed opposing results to E. prostrata in measures of root length, root surface area, relative root mass, relative shoot mass and shoot:root ratio. TCS root tissue concentrations increased with increased exposures for both E. prostrata and S. herbacea. Even though E. prostrata had the lowest levels in each measure of biomass production, it had the highest amount of root TCS bioaccumulation in the AM inoculated 4.0 g/L treatment. H. laevis was between the other two species in terms of biomass production, and did not demonstrate any exposure or inoculation effects in morphology or TCS accumulation. Overall, no clear patterns were detected, which highlights the fact that further study is required to completely understand the effects compounds like TCS can have on plant community structure, and ultimately ecosystem function.
84

Wetland Landscapes: Exploring Marsh Refrains in Norfolk County, Ontario

Gignac, Emma 20 May 2022 (has links)
Southern Ontario is an exciting place to study our relationship with wetland landscapes, as almost 75% of these ecosystems have been transformed and seized for urban or agricultural development, although the rate of wetland loss may recently be decreasing (Ontario Ministry of Natural Resources and Forestry, 2017; Ontario Biodiversity Council, 2015). This thesis is constructed around fieldwork conducted in Norfolk County during the late summer of 2020 and extensive engagement with various marsh complexes within the region. This research aims to present a more holistic understanding of our current relationship with wetland environments in Southern Ontario. This includes situating the wetland landscapes of Norfolk County within the infrastructures of the local Great Lakes region and the global and affective entanglements of the Anthropocene. Additionally, we explore certain co-constitutive present-day relationships that approximate people to wetland refrains. Finally, this research highlights the political intricacies of wetland management. Through this work, I will describe the complexities of these environments and demonstrate how being attuned to wetland landscape temporalities may be the best way to reterritorialize the wetland landscape.
85

Resistance to Flow Through Riprian Wetlands

Hodges, Clayton Christopher 16 May 1997 (has links)
Increasing interest in the role of wetlands in pollutant removal, flood plain management, and sedimentation in recent years has prompted research into hydraulic processes inherent to these systems. The research described in this thesis focuses on flow processes within ecosystems known as riparian wetlands. An attempt has been made to summarize existing research in this field to ensure that a contribution will be made to the field of hydraulics. Included in this thesis are results from laboratory models investigating flow through vegetation in riparian wetlands. Particular emphasis in this research has been placed on velocity profile measurement of flow within vegetation. Measurements were taken within various density configuration of rigid simulated vegetation for emergent and submerged cases. In addition, many of the experiments tested the effect on the velocity profile when two distinct layers of vegetation are present. The results described herein should aid in visualization of flow processes within riparian wetlands. / Master of Science
86

Examining the link between macrophyte diversity, bacterial diversity, and denitrification function in wetlands

Gilbert, Janice M. 20 July 2004 (has links)
No description available.
87

The ecology and evolution of wetland butterflies with emphasis on the genus Euphyes (Lepidoptera: Hesperiidae) /

Shuey, John Allen January 1986 (has links)
No description available.
88

A Spatial Analysis of Fish Habitats in Coastal Wetlands of the Laurentian Great Lakes

Wei, Anhua 08 1900 (has links)
The overall objective of this study was to provide a spatial pattern analysis offish distribution in the Great Lakes and to relate these patterns to shoreline features such as coastal wetlands, tributaries and substrate type. Very little is known regarding the distribution patterns of fish in the Great Lakes at the geographical scale of each lake basin. I first explored whether there were systematic patterns in distribution offish and coastal wetlands by looking at density maps of each and calculating nearest neighbor distances. I used three different classification schemes to sort the 139 fish taxa into functional categories to produce ecologically meaningful distribution maps. There were striking differences in the overall distribution pattern of nursery and spawning habitat in the five Great Lakes when data were compared for Jude and Pappas' classification taxocenes: open-water, intermediate and coastal. Overall, open-water species were the most abundant, and were also widely distributed throughout all five lakes. Coastal species were the least abundant and appeared to be restricted to the two lower lakes. The distribution pattern of coastal and intermediate taxa overlapped a great deal; both taxocenes made extensive use of the two lower lakes for spawning and nursery habitat during this synoptic survey, especially in western Lake Erie and eastern Lake Ontario. Fish distribution patterns sorted by thermal preference and by reproductive guild were compared with those sorted by taxocene. Results from a chi-square analysis indicated a high degree of overlap between thermal classes and taxocenes. There were also positive associations between many reproductive guilds and the three taxocenes, although these were not as strong as the previous comparison. I then examined spatial association between distributions of fish and coastal wetlands and other geomorphic features by testing the distribution offish along the shore of the Great Lakes and calculating the correlation between fish and coastal wetlands of Lake Ontario. A chi-square goodness-of-fit test indicated strong associations between the distribution offish and three shoreline classes: (wetland, sandy beach/dunes and bluff) and fish used coast~cl wetlands preferentially for spawning and nursery habitat at a basin-wide scale. Bivariate pattern analysis indicated that occurrences offish in L. Ontario were positively associated with both coastal wetlands and tributaries, although the relationship was considerably weaker for tributaries than for wetlands. Results from this study indicated that 1) Fish have an aggregated distribution pattern along the shores of Great Lakes and L. Ontario; 2) Coastal wetlands have an aggregated distribution pattern along the shores of Great Lakes and L. Ontario; 3) Spatial distribution offish and wetlands is positively associated; 4) The preferred utilization of coastal wetlands by majority of the Great Lakes fishes is consistent across geographic scales, from the site level to that of the entire Great Lakes basin. / Thesis / Master of Science (MSc)
89

The degradation of lignocellulosics under conditions applicable to wetlands in northern Greece

Petrou, M., Edwards, Howell G.M., Janaway, Robert C., Kavvouras, P., Thompson, Gill B., Wilson, Andrew S. January 2008 (has links)
No
90

The efficiency of the Zeekoegat artificial wetland as a biological filter of waste water

11 September 2013 (has links)
M.Sc. (Aquatic Health) / Located largely in a semi-arid part of the world, South Africa’s water resources, in global terms are extremely scarce and limited. (South Africa is one of the 30 driest countries of the world). South Africa is already categorised as water stressed with annual freshwater availability of less than 1700 mm³ /person (the index for water stress) (Blignaut and Van Heerden, 2009). South Africa is a water scarce country due to low rainfall (less than 500 mm per annum, some parts less than 200 mm: the average of 475 mm is well below the global average of 860 mm p/a.) and due to the uneven distribution of its water resources (more than 60% of the river flow arising from only 20% of the land area) which is a direct result of the climate and topography of the country (Davis and Day, 1998). South Africa is a large piece of land, far larger than for instance Germany (population of 82.7 million- Bergman and Renwick, 2003). When compared, Germany has 2169 cubic meters of water available per person while South Africa has only 1208 (Bergman and Renwick, 2003). Compared with another arid country, Australia has a population of 19.1 million and freshwater resources of 18 722 cubic meters per person (Bergman and Renwick, 2003). South Africa has close to the lowest conversion of rainfall to usable run-off from rivers of all the countries in the world (South Africa 8.6%, Australia 9.8%, and Canada 66%) (Bergman and Renwick, 2003). South Africa will also be negatively impacted by both changes in climate and the prevalence and spread of alien invasive species (Blignaut and Van Heerden, 2009). Prosperity for South Africa depends upon the sound management and utilisation of many resources, with water playing a pivotal role. Any decrease in the quality and therefore the usability of water in South Africa by 1% may result in the loss of 200 000 jobs, a drop of 5.7% of disposable income per capita, and an increase of 5% or R18.1 billion in government spending. This will further result in a 1% decrease in the GDP growth rate (Du Toit, 2010). This is reiterated by a number of other studies.

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