• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 666
  • 59
  • 46
  • 40
  • 38
  • 36
  • 26
  • 13
  • 8
  • 8
  • 8
  • 8
  • 8
  • 8
  • 5
  • Tagged with
  • 1161
  • 287
  • 187
  • 181
  • 181
  • 178
  • 177
  • 151
  • 133
  • 90
  • 90
  • 78
  • 78
  • 71
  • 67
  • 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.
321

Performance of a Surface-Flow Constructed Wetland Treating Landfill Surface-Water Runoff

Hick, Justin 11 June 2013 (has links)
Landfills are a major potential source of groundwater and surface-water contamination. The compounds that can leach from landfilled materials include dissolved organic matter, inorganic macrocomponents, heavy metals, and xebobiotic organic compounds. Landfill surface-water runoff poses a threat to the environment due to high mobility, but has not been rigorously characterized with regards to common pollutants found in landfills. It is well documented that constructed wetlands can serve as an effective treatment option for many pollutants found in landfills. The Napanee Landfill has constructed a wetland in order to treat surface-water runoff coming off the landfill. The objectives of this study were to: 1) characterize the water chemistry of surface-water runoff for an inactive landfill; 2) evaluate the treatment potential for the constructed wetland system at the Napanee Landfill; and, 3) recommend design, maintenance, and operative improvements to enhance effluent water quality. The analysis of the landfill surface-water runoff entering the Napanee Landfill constructed wetland included the pollutants nitrate, ammonia, sulphate, phosphorus, and chloride. The median inflow and outflow concentrations for all of the observed pollutants did not exceed Canadian federal or provincial water quality guidelines. There were sampling days where ammonia, phosphorus, and chloride exceeded guidelines at the inflow and days where ammonia and chloride exceeded guidelines at the outflow. The only pollutant that saw a statistically significant decrease in concentrations was sulphate, with a change of 38% from the inflow to the outflow. Other changes of note were nitrate and phosphorus concentrations increasing by 50% and 23% respectively from the inflow to the outflow. There are a variety of improvements that can be made to the Napanee Landfill constructed wetland that would increase the treatment efficiency of ammonia. Incorporating a vertical-flow wetland would increase available surface area for nitrifying bacteria growth and would provide more oxygen for nitrification processes; both would increase the potential for significant ammonia treatment. Overall, the concentrations of the pollutants found in the surface-water runoff coming off of the Napanee Landfill constructed wetland did not pose a significant threat to the environment at the time of sampling and treatment processes were only successful in reducing sulphate pollutant concentrations.
322

Growth rates and the definition of old-growth in forested wetlands of the Puget Sound region

Painter, Luke. January 2007 (has links) (PDF)
Thesis (M.E.S.)--The Evergreen State College, 2007. / Title from title screen (viewed on 1/10/2008). Includes bibliographical references (p. 48-51).
323

Planning implications of cluster housing for wetlands and their buffers

Abercrombie, Celina. January 2006 (has links) (PDF)
Thesis (M.E.S.)--The Evergreen State College, 2006. / Title from title screen viewed (1/30/2008). Includes bibliographical references (leaves 91-93).
324

Spatial and seasonal variations of freshwater macroinvertebrates, odonata and waterbirds in Luk Keng marshland, Hong Kong

Cheung, Ka-wing, January 2008 (has links)
Thesis (M. Phil.)--University of Hong Kong, 2009. / Includes bibliographical references (leaves 100-125) Also available in print.
325

The ecology of a traditional tidal shrimp pond in Hong Kong, the production and fate of macrodetritus, and implications for management /

Lee, Shing-yip. January 1988 (has links)
Thesis (Ph. D.)--University of Hong Kong, 1989.
326

Patterns of plant species richness in emergent and forestry wetlands of southeast Alaska /

Pollock, Michael Moritz. January 1995 (has links)
Thesis (Ph.D.)--University of Washington, 1995. / Vita. Includes bibliographical references (leaves [135]-151).
327

A two-year seasonal analysis of wetland vegetation at the McClintic Wildlife Management Area in Mason County, West Virginia

Blankenship, Anne Carrington. January 2005 (has links)
Theses (M.S.)--Marshall University, 2005. / Title from document title page. Includes abstract. Document formatted into pages: contains ix, 111 p. Bibliography: p. 103-106.
328

A review of stakeholder interests and participation in the sustainable use of communal wetlands : the case of the Lake Fundudzi catchment in Limpopo Province, South Africa /

Silima, Vhangani January 2007 (has links)
Thesis (M.Ed. (Education)) - Rhodes University, 2007. / A full-thesis submitted in fulfillment of the requirements of the degree of Master of Education (Environmental Education)
329

A case study of Bigodi Wetland Sanctuary as a community driven Community-Based Natural Resource Management initiative : maintaining livelihoods and wetland health

Gosling, Amanda Karen January 2012 (has links)
Community-Based Natural Resource Management (CBNRM) is considered a win-win approach to reconcile conservation with natural resource use. CBNRM aims to accomplish conservation whilst prioritising development and contributing to poverty alleviation. This study analysed the different components of a CBNRM initiative, Bigodi Wetland Sanctuary (BWS), located in western Uganda. The study was carried out by interviewing the managing committee members (n= 8) as well as local households (n= 68) regarding the manner in which the project works, and the associated benefits and constraints. The main management issues recognised were a lack of monitoring and committee cohesiveness. The information gathered through the household survey enabled the calculation of the value of local livelihood options. This was done on the premise that conservation is better accepted when land users realise the economic value of natural resources. The average annual value of household livelihoods was represented by 30% crop production, 57% natural resource use, and 13% livestock. Lastly, wetland assessments were performed using the WET-Health and WET-EcoServices methodologies from the Wetland Management Series. These assessments indicated that the impacts of local livelihoods on the wetland were currently low but potential issues could arise with the increasing human population density. Ultimately, BWS presents both environmental and social costs and benefits. With a detailed and interdisciplinary method specific recommendations of improvement can be made to reduce such costs and further reconcile the conservation of Bigodi Wetland with local natural resource use..
330

Avaliação da eficiência de wetland construído como unidade de polimento de efluente de tratamento secundário de lixiviado por lodos ativados / Evaluation of efficiency of constructed wetland as secondary treatment of wastewater polishing unit of activated sludge leachate.

Amanda Vargas Mansur 08 April 2015 (has links)
Programa de Apoio Técnico às Atividades de Ensino, Pesquisa e Extensão / Uma das dificuldades a ser enfrentada na implantação de aterros sanitários é o tratamento adequado do lixiviado gerado e seu lançamento no meio ambiente dentro dos padrões estabelecidos pela legislação. O potencial poluidor do lixiviado está ligado principalmente aos altos valores de carga orgânica que promove a redução do oxigênio disponível (utilizado na degradação da matéria orgânica) em cursos dágua, prejudicando a fauna e a flora nesses meios. O objetivo do presente trabalho foi avaliar o sistema de tratamento por wetland construído como unidade de polimento do efluente secundário de uma estação de tratamento de lixiviado de aterro de resíduos sólidos urbanos na Região Metropolitana do Rio de Janeiro. Além dos parâmetros coletivos específicos e não específicos, também foram empregados o fracionamento pelo processo de separação por membranas e ensaios de toxicidade aguda. Os resultados mostram que o wetland tem uma ação positiva como unidade de polimento refletida na redução dos parâmetros turbidez (84%), DQO (19%), amônia (30%) e sólidos totais (3%) reduzindo, assim, os impactos ambientais do lançamento do lixiviado. Contudo, a qualidade do efluente final encontra-se acima dos parâmetros de referência de controle ambiental e mostra a necessidade de um efluente secundário de melhor qualidade. Os resultados mostraram também que altos valores de DQO inerte tanto no afluente (85% em média) quanto no efluente (93,5% em média) do wetland indicam que esses lixiviados apresentam natureza refratária confirmada pelos baixos valores de biodegradabilidade no afluente (20,5% em média) e no efluente (5% em média) do wetland. O fracionamento com membranas mostrou que o afluente e o efluente do wetland possuem maiores contribuições de moléculas na fração >1 kDa. Os ensaios de toxicidade com Aliivibrio fischeri mostraram que o afluente e o efluente do wetland possuem toxicidade aguda, sendo a mesma menor na faixa com moléculas menores. / One of the challenges in the implementation of landfills is to treat the leachate generated adequately and release it into the environment within the standards established by law. The pollution potential of the leachate is connected mainly to the high organic load values which leads to reduction the available oxygen (used in the degradation of organic matter) into waterways, damaging the fauna and flora in the media. The objective of this study was to evaluate the constructed wetland as a polishing treatment system for a secondary effluent of a leachate treatment plant of municipal solid waste landfill in the metropolitan area of Rio de Janeiro. Above the specific and non-specific collective parameters also were performed a fractionation membrane separation process and testing toxicity. The results show that the wetland has a positive action as polishing unit reflected in the reduction of turbidity parameters (84%), COD (19%), ammonia (30%) and total solids (3%), reducing the environmental impacts of the leachate. However, the quality of the final effluent is in above the benchmarks of environmental control and shows the need for a secondary effluent of better quality. The results also showed that high inert COD values of both the influent (average of 85%) and in the effluent (average of 93,5%) of wetland indicate that these leachates are refractory nature confirmed by low biodegradability values in the influent (average of 20,5%) and effluent (average of 5%) of wetland. The fractionation membranes showed that the influent and effluent wetland have larger contributions molecules in the fraction> 10 kDa. The toxicity tests with Aliivibrio fischeri showed that the influent and effluent of the wetland have acute toxicity, which were lower in the range with smaller molecules.

Page generated in 0.0253 seconds