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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.
521

Desempenho de um sistema composto por um filtro anaeróbio e um wetland horizontal na produção de água para reúso predial a partir de água cinza clara

Knupp, Andrielly Moutinho 22 February 2013 (has links)
Made available in DSpace on 2016-12-23T14:04:28Z (GMT). No. of bitstreams: 1 Andrielly Moutinho Knupp.pdf: 3767260 bytes, checksum: 40743ea51e22c5e69ff89d45c24f151e (MD5) Previous issue date: 2013-02-22 / Os wetlands têm se mostrado como uma opção favorável ao tratamento de água cinza visando o reúso predial devido à boa remoção de poluentes e, principalmente, ao baixo custo de implantação e operação, além do mínimo impacto ambiental quando comparados a outros sistemas. O presente estudo teve como objetivo caracterizar físico-quimica e microbiologicamente a água cinza clara gerada em um edifício universitário; avaliar o desempenho de um wetland horizontal (WH) como pós-tratamento de um filtro anaeróbio tratando água cinza clara na produção de água para reúso predial; e estudar a aplicação do Processo Analítico Hierárquico (AHP) como ferramenta de auxílio na seleção da macrófita a ser utilizada no wetland estudado. As análises físico-químicas e microbiológicas foram realizadas segundo o Standard Methods for Examination of Water and Wastewater. O volume de água cinza gerado no edifício universitário foi de 103,1 L.p.d-1. De acordo com a caracterização da água cinza clara, o pH apresentou um valor elevado (9,0), presenças significativas de turbidez (50,9 UT), sólidos suspensos totais (44,8 mg.L-1), matéria orgânica (178,3 mgO2.L-1 de DQO e 41,3 mgO2.L-1 de DBO5,20), SO42- (60,1 mg.L-1) e microrganismos (2,2x104 NMP.100mL-1 de coliformes totais e 8,5x102 NMP.100mL-1 Escherichia coli), além de baixas concentrações de nitrogênio (2,7 mg.L-1 NTK e 2,0 mg.L-1de NH3) e fósforo (0,4 mg.L-1). Vale ressaltar que a água cinza estudada possui uma relação DBO5,20/DQO variando de 0,2 a 0,3, e que, apesar da baixa biodegradabilidade, o tratamento biológico ainda é possível, porém sob condições limitantes de degradação. No que diz respeito ao desempenho do sistema de tratamento de água cinza, foram avaliados quatro períodos de testes no WH, sendo estes caracterizados pelos tempos de detenção hidráulica (TDH) de 0,7; 1; 1,9 e 3,2 dias. Como resultado, observou-se que o efluente proveniente do WH apresentou melhor desempenho para o TDH de 3,2 dias ao longo dos períodos analisados, mostrando-se adequado quando utilizado como pós-tratamento de um filtro anaeróbio. Foram alcançadas eficiências de remoção globais médias de 80% para turbidez e sólidos suspensos totais. Além disso, também foram alcançadas eficiências de remoção de 81% para DQO e 66% para DBO5,20. A densidade média de E. coli obtida no efluente do WH foi de 3,1x10² NMP.100mL-1. O AHP foi executado em três etapas: identificação das macrófitas utilizadas nos wetlands , seleção de dez macrófitas mais utilizadas neste tipo de tratamento e aplicação do método AHP para as condições da região da Grande Vitória-ES. Como resultado da utilização do AHP, obteve-se a Equisetum hyemale L. e a Canna x generalis como as plantas mais adequadas para o tratamento de água cinza por meio de wetlands / The wetlands have been shown as a favorable option for the greywater treatment aiming the building reuse due to the good pollutants removal, and mainly, the low cost of implantation and operation, as well as minimal environmental impact when compared with another systems. The present study aimed to characterize physico-chemical and microbiologically the light greywater generated in a corporate building; evaluate the performance of horizontal wetland (HW) as a post-treatment of an upflow anaerobic filter (AF) treating light greywater in the water reuse building production; and to study the application of the Analytic Hierarchy Process (AHP) as assistance tool in the selection of the macrophyte to be used at the evaluated wetland. The physico-chemical and microbiological analysis were performed according the Standard Methods for Examination of Water and Wastewater. The greywater s volume generated in the corporate building was 103,1 L.p.d-1. According with the characterization of the light greywater, the pH showed a high value (9.0), significant presences of turbidity (50.9 TU), TSS (44.8 mg.L-1), organic matter (178.3 mgO2.L-1 COD and 41.3 mgO2.L-1 DBO5,20), SO42- (60.1 mg.L-1) and microorganisms (2.2x104 NMP.100mL-1 total coliforms and 2.0x102 NMP.100mL-1 E. coli), in addition of low nitrogen and phospohrous concentrations. Note that the greywater evaluated has a ratio DBO5,20/DQO ranging 0.2 at 0.3, and that despite the low biodegradability, the biological treatment is still possible, but under limitant degradation conditions. About the performance of greywater treatment system, were analyzed four periods of experiments, being characterized by the hydraulic retention time (HRT) of 0.7; 1.0; 1.9 e 3.2 days. Such as result, observed that the HW effluent showed better performance for the HRT of 3.2 days over the analyzed periods, making it adequate when used such as post-treatment of an anaerobic filter. Were achieved global removal efficiencies mean of 80% to turbidity and total suspended solids. Moreover, was reached too removal efficiencies of 81% COD and 66% BOD5,20. The mean density obtained of E. coli in the HW effluent was 3.1x10² NMP.100mL-1. The AHP was executed in three steps: identification of the macrophytes used at the wetlands, selection of ten more macrophytes used in this treatment type and application of the AHP method to the Greater Victoria s Region conditions. As result of the AHP application, obtained the Equisetum hyemale L. and Canna x generalis such as the more appropriate plants to the greywater treatment by wetlands
522

Managing Invasive Plants During Wetland Restoration: the Role of Disturbance, Plant Strategies, and Environmental Filters

Osland, Michael Johannes January 2009 (has links)
<p>Since wetlands provide many important ecosystem services, there is much interest in protecting existing wetlands and restoring degraded wetlands. Yet, degraded wetlands and restoration sites are often vulnerable to plant invasions that can hinder restoration success. Invasive plants typically reduce biodiversity and alter important ecosystem functions and services. This dissertation examines the ecological impact and management of invasive plant species during wetland restoration with a focus on three important drivers of plant community change in wetland ecosystems: disturbance, plant strategies, and environmental filters.</p><p>The investigations included in this research were conducted in a tropical dry wetland (Palo Verde Marsh, Palo Verde National Park, Costa Rica) and a temperate piedmont riparian forest (Sandy Creek, Duke Forest Stream and Wetland Assessment and Management Park, Durham, North Carolina). In these experiments, the primary species of interest are <italic>Typha domingensis</italic> Pers. (cattail; Typhaceae), <italic>Ligustrum sinense</italic> Lour. (Chinese privet; Oleaceae), <italic>Arundinaria gigantea</italic> (Walter) Muhl. (giant cane; Poaceae), and <italic>Microstegium vimineum</italic> (Trin.) A. Camus (Japanese stiltgrass; Poaceae).</p><p>The expansion of <italic>Typha</italic> into wetlands historically not dominated by cattail typically occurs in response to natural and anthropogenic perturbations. Management approaches that reduce <italic>Typha</italic> dominance, increase diversity, and restore or maintain wetland ecosystem services are of interest worldwide. The objective of the first phase of the research was to investigate a unique <italic>Typha</italic> removal method that is used in one of the most dynamic and ecologically important wetlands in Central America (Palo Verde Marsh, Palo Verde National Park, Costa Rica; a Ramsar Wetland of International Importance). Palo Verde Marsh is a tropical dry wetland with distinct and extreme wet and dry seasons; it is flooded during the wet season and has no standing water for much of the dry season. Palo Verde Marsh has historically provided important habitat for very large populations of migratory birds. However, a cattail (<italic>T. domingensis</italic>) expansion in the 1980s greatly altered the plant community and reduced avian habitat. Since then, <italic>Typha</italic> has been managed using fangueo (a Spanish word, pronounced as "fahn-gay-yo" in English). During fangueo, <italic>Typha</italic> is crushed and locally removed by a tractor with metal paddle wheels. I applied a <italic>Typha</italic> removal treatment at three levels (control, fangueo, and fangueo with fencing to exclude cattle grazing) at Palo Verde Marsh. Fangueo was applied at the beginning of the dry season resulting in a large reduction in <italic>Typha</italic> dominance (decreased aboveground biomass, ramet density, ramet height), an increase in open areas with no vegetation, and a 98 and 5-fold increase in avian density and richness, respectively. Importantly, fangueo had no apparent long-term impact on any of the soil properties measured (including bulk density). Interestingly, low soil and foliar N:P values indicate that Palo Verde Marsh and other wetlands in the region may be nitrogen limited. The fangueo process is an effective method for restricting <italic>Typha</italic> expansion and increasing plant and avian diversity. I present a model that illustrates the impact of <italic>Typha</italic> management and seasonal flooding on the plant and avian community. The technique might be adopted or modified for the restoration and management of <italic>Typha</italic> and other invasive emergent plants in other wetlands.</p><p>The second objective of this research was to better quantify the impact of the distinct and extreme anaerobic/aerobic annual cycle on the plant community in Palo Verde Marsh. Since the impact of seasonal flooding on the plant community in seasonal wetlands is often most evident after disturbance, I created gaps in the wetland vegetation via the mechanical removal of emergent vegetation and then measured plant community change using surveys of the wet and dry season standing vegetation, the seed bank, and <italic>in situ</italic> seedling recruitment. As expected, seasonal flooding acted as an environmental filter and resulted in distinct dry and wet season assemblages. The dominant plant life forms present after vegetation removal differed between seasons with emergents dominating during the dry season and floating-rooted, free-floating, and submerged species more dominant during the wet season. I identified common species that are characteristic of both seasonal assemblages and used indicator species analyses to identify species that are only likely to be found during the wet season. I also characterized the seed bank at this site; like most seasonal wetlands, plant species' resilience in this wetland were dependent upon a large and diverse seed bank which allowed many species to revegetate after disturbance and the extreme wet/dry conditions which acted like environmental filters.</p><p>In addition to the experiments conducted in Palo Verde Marsh, this dissertation also presents the results from an experiment in a temperate riparian restoration site in the North Carolina Piedmont (Sandy Creek, Duke Forest Stream and Wetland Assessment and Management Park, Durham, NC). Since riparian restoration efforts in the southeastern U.S. are often hindered by invasive non-native plants, there is much interest in approaches that can be used to reduce the impact of invasive non-native plant populations at the local level (e.g., a restoration site). In addition to the impact of non-native species-specific removal efforts, there is also much interest in the identification and assessment of native competitive-dominant plant species that can be used during riparian restoration to support important ecosystem functions and reduce non-native invasibility. <italic>Ligustrum sinense</italic> (Chinese privet) is a very common invasive non-native shrub in the region. <italic>Arundinaria gigantea</italic> (giant cane) is a native bamboo species that used to be very abundant in riparian and wetland ecosystems in the region. The objectives of this phase of the research were to: (1) measure the plant community response to removal of mature <italic>L. sinense</italic> individuals; and (2) quantify planted <italic>A. gigantea</italic> clonal expansion in the presence of other plants, particularly common non-native invasive species. Due to its potential for rapid growth and expansion, it was hypothesized that <italic>A. gigantea</italic> would be able to compete with common non-native species and reduce non-native invasibility. In a three-year split-plot experimental design, I applied a Privet-Presence treatment at two levels (Privet Present, Privet Removed) and a Cane-Planting treatment also at two levels (Cane, No Cane). The privet removal treatment resulted in 100% mortality of mature privet individuals. After privet removal, <italic>L. sinense</italic> seedlings recruited into these plots but growth has been very slow and these <italic>L. sinense</italic> individuals are not yet dominant. The privet canopy allows minimal understory plant recruitment and growth and privet removal resulted in an increase in species richness and diversity in the first year. However, in these Privet-Removed plots, a non-native invasive annual grass (<italic>Microstegium vimineum</italic>) invaded, became the most dominant species, and reduced species richness and diversity. In Privet-Removed plots, <italic>A. gigantea</italic> clonal expansion (i.e., ramet density, genet area, ramet diameter, and ramet height) was small in the first year but increased in the second and third years. Importantly, in Privet-Removed plots where <italic>A. gigantea</italic> was planted, <italic>M. vimineum</italic> cover was lower and species richness and diversity were greater; planting <italic>A. gigantea</italic> appears to have facilitated the establishment of other species and, in the process, increased diversity.</p><p>Our results emphasize several general conclusions that are applicable to other restoration efforts in other ecosystems with other plant species. First, during ecological restoration, invasive non-native plant removal alone will typically not restore native plant communities. Non-native invasive plant populations are typically very resilient to removal. Hence, long-term reductions in non-native invasibility will often require additional management efforts. For example, in the tropics my research showed the effectiveness of Fangueo for reducing <italic>Typha</italic> monocultures and increasing native plant and bird diversity. Another approach for improving ecosystems functions and reducing non-native invasibility after invasive plant removal is to carefully select and plant native species with competitive-dominant traits that will be able to compete with invading non-native species and resist invasion. Although this seemingly simple approach is often used by restoration practitioners, the results are rarely monitored and surprisingly few studies are designed to explicitly identify and investigate the performance of these important native competitive-dominant species.</p> / Dissertation
523

Efterpolering med våtmark : Hur kan det användas vid Haga reningsverk?

Carlsen, Inger-Marie January 2015 (has links)
The aim of this report is to present a proposal for a constructed wetland as a complement toHaga treatment plants, Surahammar. First, a literature study in the subject was made andthen a case study was conducted, where Ekeby and Trosa wetland was visited. Parallel anarchival study was performed and several field visits were made to the proposed site toinvestigate the local conditions for constructing a wetland adjacent to Haga treatment plants.Finally, a proposal for the design of the constructed wetland was made. The proposalincludes an oxygenating area for reduction of ammonium to nitrate followed by a system ofdams and channels to convert nitrate to nitrogen diffuses into the air. Phosphorus removaltakes place throughout the residence time in the wetland, as well as reduction of the bacterialload. Expected results for the outgoing water from the wetland is that P-tot can be reduced to0.10-0.11 mg / l, N-tot can be reduced to 11-14 mg / l, a reduction of E. coli, fecal streptococciand intestinal streptococci by 70-99% and a little reduction of residues from drugs take placedue to oxygenation and the UV-irradiation of the water. / Allt vatten här på jorden ingår i den hydrologiska cykeln, så även det renade avloppsvattnet.Avloppsvatten innehåller bland annat kväve och fosfor vilka bidrar till övergödningen avsjöar, vattendrag och hav. Övergödningen är ett utbrett problem och i Västmanland är 53 %av länets sjöar och vattendrag utsatta för det.Syftet med den här rapporten är att ta fram ett förslag till våtmark för Haga reningsverk,Surahammar. Först har information om hur en våtmark kan användas för efterpolering avrenat avloppsvatten tagits fram för att därefter nyttjas som grund i ett förslag till våtmark förHaga reningsverk, Surahammar. Först gjordes en litteraturstudie inom ämnesområdet ochdärefter gjordes en fallstudie där Ekeby och Trosa våtmark besöktes. Parallellt utfördes enarkivstudie och flera områdesbesök på den tilltänkta platsen för att få fram vilkaförutsättningar som finns för att anlägga en våtmark i anslutning till Haga reningsverk ochsist gjordes ett förslag på en våtmark.Anledningen till att anlägga en våtmark kan vara flera, men att avskilja fosfor, kväve samtbryta ner organiskt material är vanliga orsaker. En våtmark fungerar som ett kompletterandesteg till det ordinarie reningsverket och minskar belastningen på recipienten. Hur mycketutsläppen reduceras beror på många faktorer och egenskaper där utformning, vattnetsuppehållstid, syresättning och tillgång till organiskt material är viktiga men även parametrarsom förbehandling av avloppsvattnet och belastningen på våtmarken spelar stor roll. Ävenväxtligheten i våtmarken påverkar det slutliga resultatet, både vad det gäller vad och hurmycket som avskiljs. Avskiljningen av fosfor och kväve sker främst genom sedimentation ochnäringsupptag till växter samt att kväve även avskiljs vid denitrifikation. För den långsiktigaavskiljningen av kväve från vattnets kretslopp är nitrifikation och denitrifikation de som harstörst betydelse. Nitrifikationsprocessen är när ammoniumjoner omvandlas till nitratjoneroch det kräver god tillgång på syre, därefter följer denitrifikationen när nitratjonerna undersyrefria förhållanden omvandlas till kvävgas som diffunderar upp i atmosfären. För attnitrifikationsprocessen ska kunna fungera krävs antingen att det finns ennitrifikationsanläggning i reningsverket eller en syresättningsfas i våtmarken. Det kan skapasgenom att börja våtmarken med en översilningsäng, där det renade avloppsvattnet får strilaner över en bevuxen äng. Vattnet syresätts av luften och nitrifikationsbakterier som trivs bra iväxtligheten utför nitrifikationsprocessen och omvandlar ammoniumjonerna till nitratjoner.Därefter följer ett system av dammar och kanaler där denitrifikationsprocessen tar vid ochomvandlar nitratjonerna till harmlöst kväve. Även i dammar och kanaler har växtlighetenstor betydelse eftersom det bildas biofilm, ett tunt lager av bakterier på växterna, som deltar iden biologiska processen av nedbrytning av organiskt material samt avskiljning av fosfor ochkväve i vattnet.När vattnet passerar genom våtmarken sker också en reducering av antalet bakterier somfinns i det renade avloppsvattnet. Mätningar av E. coli, fekala streptokocker, Koliformabakterier och intestinala enterokocker visar på att halterna kan reduceras kraftigt. Även vissaläkemedel visar tendenser till att brytas ned, men läkemedel är en komplex grupp och detfinns begränsad kunskap om deras omvandling och påverkan i miljön. Det finns dock indikationer om att nedbrytningen av läkemedelsrester är högre i de våtmarker som harsyresättande delar som till exempel översilningsäng.Haga reningsverk är beläget strax utanför Surahammars tätort och har idag en kulvert somleder ut det renade avloppsvattnet från verket till recipienten. Mellan Haga och recipientenligger ett markområde på cirka 750 gånger 750 meter som skulle kunna utnyttjas till envåtmark. Redan idag ligger utsläppsvärdena för Haga reningsverk under de tillåtna halternamen en önskan att ytterligare minska belastningen på miljön finns. Vid analysering avutsläppsvärden för Haga reningsverk framkom att ammoniumkväve utgör en stor andel avutgående totalkväve samt att halterna av totalfosfor, BOD7 och suspenderade ämnen är lågatill måttliga. Ett förslag på våtmark anpassat till de förutsättningar som råder vid Hagareningsverk har tagits fram och presenteras i rapporten. Våtmarken föreslås innehålla tvåsektioner med först en översilningsäng för att reducera den höga andelen ammoniumkväveoch därefter ett damm och kanalsystem för att reducera nitratkvävet. Under hela processensker avskiljning av fosfor samt reducering av bakterier och en viss nedbrytning avläkemedelsrester. Förväntade resultat för det utgående vattnet från våtmarken är att P-totkan reduceras till 0,10–0,11 mg/l, N-tot kan reduceras till 11–14 mg/l, en reducering av E.coli, fekala streptokocker och intestinala streptokocker med 70-99 % samt att en vissminskning sker av läkemedelsrester tack vare syresättning och solens UV-bestrålning avvattnet.
524

Created wetlands in Shing Mun River, Sha Tin

練偉東, Lin, Wai-tung. January 1999 (has links)
published_or_final_version / Architecture / Master / Master of Landscape Architecture
525

The remote sensing of papyrus vegetation (Cyperus papyrus L.) in swamp wetlands of South Africa.

January 2010 (has links)
Papyrus (Cyperus papyrus .L) swamp is the most species rich habitat that play vital hydrological, ecological, and economic roles in central tropical and western African wetlands. However, the existence of papyrus vegetation is endangered due to intensification of agricultural use and human encroachment. Techniques for modelling the distribution of papyrus swamps, quantity and quality are therefore critical for the rapid assessment and proactive management of papyrus vegetation. In this regard, remote sensing techniques provide rapid, potentially cheap, and relatively accurate strategies to accomplish this task. This study advocates the development of techniques based on hyperspectral remote sensing technology to accurately map and predict biomass of papyrus vegetation in a high mixed species environment of St Lucia- South Africa which has been overlooked in scientific research. Our approach was to investigate the potential of hyperspectral remote sensing at two levels of investigation: field level and airborne platform level. First, the study provides an overview of the current use of both multispectral and hyperspectral remote sensing techniques in mapping the quantity and the quality of wetland vegetation as well as the challenges and the need for further research. Second, the study explores whether papyrus can be discriminated from each one of its coexistence species (binary class). Our results showed that, at full canopy cover, papyrus vegetation can be accurately discriminated from its entire co-existing species using a new hierarchical method based on three integrated analysis levels and field spectrometry under natural field conditions. These positive results prompted the need to test the use of canopy hyperspectral data resampled to HYMAP resolution and two machine learning algorithms in identifying key spectral bands that allowed for better discrimination among papyrus and other co-existing species (n = 3) (multi-class classification). Results showed that the random forest algorithm (RF) simplified the process by identifying the minimum number of spectral bands that provided the best overall accuracies. Narrow band NDVI and SR-based vegetation indices calculated from hyperspectral data as well as some vegetation indices published in literature were investigated to test their potential in improving the classification accuracy of wetland plant species. The study also evaluated the robustness and reliability of RF as a variables selection method and as a classification algorithm in identifying key spectral bands that allowed for the successful classification of wetland species. Third, the focus was to upscale the results of field spectroscopy analysis to airborne hyperspectral sensor (AISA eagle) to discriminate papyrus and it co-existing species. The results indicated that specific wavelengths located in the visible, red-edge, and near-infrared region of the electromagnetic spectrum have the highest potential of discriminating papyrus from the other species. Finally, the study explored the ability of narrow NDVI-based vegetation indices calculated from hyperspectral data in predicting the green above ground biomass of papyrus. The results demonstrated that papyrus biomass can be modelled with relatively low error of estimates using a non-linear RF regression algorithm. This provided a basis for the algorithm to be used in mapping wetland biomass in highly complex environments. Overall, the study has demonstrated the potential of remote sensing techniques in discriminating papyrus swamps and its co-existing species as well as in predicting biomass. Compared to previous studies, the RF model applied in this study has proved to be a robust, accurate, and simple new method for variables selection, classification, and modelling of hyperspectral data. The results are important for establishing a baseline of the species distributions in South African swamp wetlands for future monitoring and control efforts. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.
526

The geomorphology of wetlands in the upper Mooi River catchment, KwaZulu-Natal.

Longmore, Jennifer Lyn. January 2001 (has links)
Wetlands are now recognized as being an integral component of the physical landscape. Geomorphology has recently been recognised by wetland scientists as being of fundamental importance in wetland genesis, maintenance and evolution, thereby providing the context for informed, effective wetland management and conservation. At present there exists a paucity of geomorphological wetland research in South Africa. A hydro-geomorphic approach was adopted to attain an understanding of wetland genesis, distribution and functioning of a range of different palustrine wetland systems in the upper Mooi-River Catchment of KwaZulu-Natal. The physical, chemical and landscape-morphological characteristics of wetland soils were investigated to interpret the processes operating within those wetland systems. Both field and laboratory work suggest that wetland creation and maintenance in the upper Mooi River catchment may be attributed primarily to climatic factors, landscape position, landform and geological characteristics. These factors were found to cumulatively control the hydrological characteristics of wetlands, which impart an important influence on internal wetland conditions. While soil properties do not appear to be a primary factor in the establishment of these wetlands, they are nevertheless found to be important in the regulation of the hydrological dynamics of wetland systems. The close interdependence between wetlands and the surrounding landscape and the hydrological cycle is evident in the wetland systems investigated. Geomorphic processes within wetlands such as overbank flooding, overland flow, sedimentation, piping, leaching, soil swelling, shrinkage and cracking and channel incision and dynamics were found to be important variables in determining the nature and internal characteristics of wetland systems. In several of the systems investigated, all of the above mentioned processes were operative, while in other systems, a number of these processes were either insignificant or absent. Canonical Variate Analysis indicated that while commonalities exist between the palustrine wetland systems investigated in this study, significant differences were found between different groups. This supports the argument that a subclassification of the palustrine system into five different palustrine wetland types is warranted. While the scope of the present research did not allow for an extensive investigation of suitable methods of rehabilitation, the study suggests that an understanding of geomorphic process and wetland dynamics will be beneficial to wetland management and conservation as a whole. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2001.
527

Festlegung und Mobilisierung von Uran und seinen radioaktiven Zerfallsprodukten in kohlenstoffreichen Gewässersedimenten / Fixation and mobilisation of uranium and its radioactive decay products in C-richwater sediments

Nassour, Mohammad 19 September 2014 (has links) (PDF)
The main aim of this work was to investigate the extent of uranium and radium -fixation and mobilization at the interface of mining influenced surface water and sub-hydric soils, sediment and plant detritus. A freshwater ecosystem (stream channels in an alder swamp forest – Alno-Lemnetum with low residence time shallow ponds) developed directly below a mining site (Neuensalz) and influenced by uranium containing water served as investigation site for the identification of possible fixation and mobilization mechanisms. In addition, investigations were carried out on sediments in a water reservoir downstream of the examined abandoned mining site. It could be shown, that radium concentrations of the examined surface water (2001 – 2004) are only slightly higher compared to the range of geogenic levels for German surface waters, and that its activity concentrations decreased along the investigated flow path. In contrast, uranium concentrations are well above geogenic levels and the concentration level stays high along the whole water pathway through the study area. The U-238:Ra-226 ratio of the examined surface water from the spring to a pond outflow significantly increased. The uranium chain activity concentrations in the sediments determined in this study partly exceeded considerably the regional geogenic level. For the sediment water the 238U: 226Ra ratio in the first part of the flow path is significantly shifted in favor of radium while in the second part the ratio is shifted in favor of uranium. There were indications that the dissolved uranium is transported in the form of soluble carbonate complexes. Radium however is rather fixed under dominantly oxidizing conditions along the mainly turbulent mixed shallow water pathway. The fixation of uranium and radium in the upper section of the pathway (direct below the spring) was found to be inorganically, whereas in the second part organic bonds are more indicated. The influence of allochthonous organic carbon as main metabolic energy source for low order lotic ecosystems on the fixation of uranium was investigated by analyzing, the effects of leaves (coarse particulate organic matter: CPOM) and their degradation products (mainly fine particulate organic matter: FPOM and biofilms etc.). It was found that the highly mobile fraction of uranium in the water pathway, preferably present under the given conditions in the form different uranyl-carbonato-complexes, is efficiently fixed on fresh organic plant material (plant litter, leaves) in the first steps of organic matter decomposition within a few days. But it also can be immobilized relatively stable. It was also found that CPOM is a temporary sink for uranium, which may be sedimented depending on the turbulence flow and discharge. This may contribute to the directional removal of uranium from the water into the sediment. Finally this work analyzed the conditions in the pelagic and benthic zone of the Neuensalz pre dam of the Pöhl reservoir, which is located downstream of the mining site. It presents a periodically stagnant water body with seasonally continuous sedimentation, a possible stable sink of uranium and products of radioactive decay in early diagenesis. Water samples of the pelagic zone and undisturbed sediment cores were taken and analyzed during winter stagnation. The results are discussed in front of seasonal changes in water chemistry and load data. U-238 and Ra-226 showed a culmination of activity concentrations in the sediment horizons from 25 to 35 cm depth, in particular at a centrally located sampling point (K3). At this point highest activity concentrations of 238U were found with a median value of 770 Bq*kg-1 at a depth of 30 cm. At the same location 226Ra shows activity concentrations of 250 Bq*kg-1(median). Based on the Cs-137 dating method a sedimentation rate of 1.5 cm*yr-1 was calculated for the pre-dam Neuensalz sediment. On average sedimentation rates for 238U of 3,7 ± 1,1 kBq*m-2*yr-1 and for 226Ra of 3,5 ± 0,5 kBq*m-2*yr-1 were calculated. Furthermore, a total uranium stock of 68 ± 6 kg per hectare in the sediment was estimated. In connection with a sedimentation period of 23 years, the uranium inventory in the sediments would correspond to a portion of approx. 18 % of the uranium feed by the water influx estimated for the same period. This estimation did not take into account a geogenic portion and other sources like fertilizer. For radium, the situation is reversed. An extrapolation of the cumulative load for the same period results in a lower value by almost a factor of 100 compared to uranium. This compares with a radium inventory in the sediment, which is about 15 times higher than the projected load. This leads to the conclusion that in addition to the supply from the mining legacy also the geogenic background and/or discontinuous particulate import (via storm water stream runoff etc.) has to be considered. The analysis of the bonding stability and related potential mobilization of the sedimentary uranium using sequential chemical extraction shows that most of the uranium is found in the organic fraction over the entire sediment layer, which may be identified as organically bound or as uraninite. In conclusion not only radium is immobilized near to the source but also a relevant share of uranium is permanently fixed even in/on durably deposited organic matter despite eu-trophic conditions with high nitrate load, traceable in deeper sediment layers due to e.g intensive land use. / Hauptziel der vorliegenden Arbeit war die Untersuchung des Umfangs der Festlegung bzw. Mobilisierung von Uran und Radium an der Grenzfläche von Bergbau beeinflußtem Oberflächenwasser und subhydrischen Böden, Sedimenten sowie Bestandsabfall (Detritus). Als Untersuchungsgebiet zur Identifizierung entsprechender Fixierungs- und Mobilisierungsmechanismen diente ein Süßwasser - Ökosystem (Bach in einem Erlenbruchwald – Alno-Lemnetum – und integrierte flache Teiche mit geringer Verweilzeit) unterhalb eines ehemaligen Uranerzbergbau-Gebietes (Neuensalz), das von uranhaltigem Wasser durchströmt ist. Darüber hinaus Sedimentanalysen eines periodisch stagnierenden Wasserkörpers (Vorsperre der Talsperre Pöhl) im Abstrombereich der untersuchten Bergbaualtlast vorgenommen. Es konnte gezeigt werden, dass die Radiumkonzentration des Oberflächenwassers (2001-2004) geringfügig über der des geogenen Niveaus für deutsche Oberflächenwässer liegt und dass die entsprechende Aktivitätskonzentration von Radium entlang der untersuchten Fließstrecke beginnend mit einer Quelle an einem Tailingdamm deutlich abnimmt. Dagegen liegen die Urankonzentrationen des Oberflächenwassers deutlich über dem geogenen Hintergrund. Seine Aktivitätskonzentrationen bleiben entlang der Fließstrecke weitgehend stabil. Das 238U:226Ra-Verhältnis des Oberflächenwassers wird sich entlang der Fließstrecke von der Quelle unterhalb des Tailingdammes bis zum Abfluss aus der ersten, schwächer durchflossenen kleinen Senke (Forellenteich) erhöht. Die in dieser Arbeit ermittelten Aktivitätskonzentrationen der untersuchten Nuklide der Sedimente lagen zum Teil erheblich über dem geogenen Niveau der Region. Das 238U:226Ra-Verhältnis des Bachsediments ist im ersten Teil der Fließstrecke deutlich zugunsten des Radiums verschoben, während es im zweiten Teil zugunsten von Uran verschoben ist. Dies weist darauf hin, dass das gelöste Uran in Form carbonatischer Komplexe transportiert wird. Radium wird dagegen unter den vorherrschenden oxidierenden Bedingungen entlangder Fließstrecke eher fixiert. Für die Festlegung von Uran und Radium wurde im oberen Teil der Fließstrecke (direkt unterhalb der Quelle) eher auf anorganische Bindungen geschlossen, während die Fixierung im zweiten Teil der Fließstrecke eher organischer Natur ist. Da im Oberlauf von Fließgewässern allochthoner organischer Kohlenstoff die wesentliche die Energiequelle für alle Ökosystemfunktionen bildet und eine besondere Funktion mit Blick auf Untersuchungsziel vermutet werden kann, wurde die Wirkung von Laub (grob- organisches Material: CPOM) und seinen Abbauprodukten (fein-partikuläres organisches Material: FPOM, Biofilm usw.) auf die Fixierung von Uran analysiert. Es wurde festgestellt, dass das im Wasserpfad sehr mobile Uran, welches unter den gegebenen Bedingungen vorzugsweise in verschiedenen Uranyl-Carbonato-Komplexen vorliegt, nicht nur an frischer organischer Substanz pflanzlichen Ursprungs (Bestandesabfall, Laub) im Verlauf biologischen Abbaus effizient gebunden und festgelegt wird, sondern auch sehr stabil immobilisiert werden kann. Es wurde auch ermittelt, dass CPOM ein temporärer Speicher für Uran ist, welcher je nach Fließgeschwindigkeit sedimentieren und damit zum gerichteten Transfer von Uran aus dem Wasser in das Sediment beitragen kann. Der anteilige Austrag über das verstärkt gebildete DOC über den Laubeintrag ist relativ gering. Schließlich wurden die Verhältnisse mit Bezug zur Fragestellung in der pelagischen und benthischen Zone der Vorsperre Neuensalz der Talsperre Pöhl analysiert, die stromabwärts des Bergbaugebietes anschießt. Die Vorsperre stellt einen periodisch stagnierenden Wasserkörper mit saisonaler kontinuierlicher Sedimentation dar und damit eine mögliche stabile Senke für Uran und seine radioaktiven Zerfallsprodukte in der Frühdiagenese. Wasserproben der pelagischen Zone und ungestörte Sedimentkerne wurden in der Phase der Winterstagnation entnommen, analysiert und unter Berücksichtigung saisonaler Unterschiede bezüglich Wasserchemie und Frachtdaten disskutiert. Für U-238 und Ra-226 zeigt sich eine Kulmination der Aktivitätskonzentration in den mittleren Sediment- Horizonten von 25-35 cm Tiefe, insbesondere an der Probenahmestelle K3. Dort fanden sich auch die höchsten Aktivitätskonzentrationen der Vorsperre für 238U mit einem Medianwert von 770 Bq*kg-1 in einer Tiefe von 30 cm. Für Ra-226 fand sich am selben Ort eine Aktivität von 250 Bq*kg-1 (Median). Anhand der Datierung mithilfe der Cs-137 Methode wurde für das Sediment der Vorsperre Neuensalz eine Sedimentationsrate von 1,5 cm*a-1 errechnet. Für Uran ergab sich eine Sedimentationsrate von 3,7 ± 1,1 kBq*m-2*a-1 und für Ra-226 eine solche von 3,50 ± 0,5 kBq*m-2*a-1. Darüber hinaus wurde die im Schnitt ca. 40 cm mächtigen Sedimente ein Uranvorrat von 68 ± 6 kg pro Hektar bilanziert. In Verbindung mit der Dauer des Bilanzzeitraumes der Sedimentation (23 Jahre) entspräche das in der Vorsperre vorgefundene Uraninventar einem Anteil von ca. 18 % der für diesen Zeitraum abgeschätzten Uranfracht im Wasserzufluss, wobei der geogene Anteil des Urans und die Ausbringung von Phosphatdüngemitteln in den Sedimenten noch nicht berücksichtigt ist. Für Radium sind die Verhältnisse umgekehrt. Wenn aus den gegenwärtigen Aktivitätskonzentrationen im Zufluss auf eine kumulative Fracht für den 23-jährigen Bilanzierungs- bzw. Betrachtungszeitraum hochgerechnet wird, ergibt sich ein fast um den Faktor 100 geringerer Wert, verglichen mit Uran. Dem steht ein Radiuminventar im Sediment gegenüber, welches etwa 15-mal größer als diese hochgerechnete Fracht ist. Daraus ist abzuleiten, dass neben der relativ geringen wassergelösten Zufuhr aus der Bergbaualtlast dem gegogenen Hintergrund im sedimentierenden Substrat sowie diskontinuierlich Partikel (über Regenwasserabfluss) Bedeutung beizumessen ist. Bei der Analyse der Bindungsverhältnisse des sedimentären Urans (sequentielle Extraktion) wurde der größte Anteil des Urans im Sediment als Uraninit bzw. als organisch gebunden identifiziert. Insgesamt ist zu schließen, dass nicht nur Radium in der Nähe von Quellen immobilisiert wird, sondern auch Uran eine dauerhafte Fixierung in ständig abgelagertem organischem Material erfährt. Diese Fixierung ist trotz eutropher Bedingungen mit hoher Niratbelastung stabil und in tieferen Sedimentschichten nachweisbar.
528

The death of a great land ritual, history and subsistence revolution in the southern highlands of Papua New Guinea /

Ballard, Chris. January 1995 (has links)
Thesis (doctoral)--Australian National University, 1995. / Title from screen.
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Podzemní biomasa ostřice štíhlé (\kur{Carex acuta\kur{}}) v travinném mokřadu / Below-ground biomass of \kur{Carex acuta} in a graminoid wetland

NEŠPOR, Marek January 2015 (has links)
This thesis is part of the project GA CR P504 / 11/1151 "The role of plants in the greenhouse gas balance Carex fens". The aim of this thesis is to evaluate the seasonal dynamics of Carex acuta belowground biomass in model grassland wetlands (the "wet meadows") near Třeboň. Belowground biomass of C. acuta L. was sampled using the destructive method. The samples were taken on four dates in 2014. On each date, three hummocks of C. acuta and three soil samples in their immediate vicinity were sampled on each date. Live roots had a greater dry weight than decaying roots on all sampling dates. Their total dry weight varied slightly, depending on season. The ratio of live roots to decaying roots did not differ much. The weight of live roots in hummock was almost always higher than that of the dead ones. The dry weight of living roots was always greater in the hummock than below it. Their total weight varied slightly during the year. Aquatic roots formed only a small part of the dry weight of live roots in hummocks. A greater total belowground dry weight found on 21st December 2014, in comparison with 5th August 2014, was associated with a greater amount of rhizomes of other plant species. The shoots increased their dry weight during the year. Maximum weight of tillers was recorded on 8th August 2014. There were no dead shoots on 25th March 2014. Dry weights of dead tillers were largely similar throughout the year. The volumetric soil water content (%) was usually higher in the upper soil layers. The bulk density of the soil was almost identical on all sampling sites, except for the top layer on site 1, where it was considerably lower.
530

Construção participativa de sistemas de tratamento de esgoto doméstico no Assentamento Rural Olga Benário-MG / Participatory development of wastewater treatment systems in the Rural Settlement Olga Benário-MG

Pires, Felipe Jacob 30 November 2012 (has links)
Made available in DSpace on 2015-03-26T13:28:13Z (GMT). No. of bitstreams: 1 texto completo.pdf: 5265265 bytes, checksum: 6ea4809ccb3b5d8cb07a565ff0282116 (MD5) Previous issue date: 2012-11-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In Brazilian rural areas there is still a lack of basic sanitation, especially concerning to wastewater treatment, exposing the communitis to all sorts of contamination. The participation of rural communities in the decision making for choosing an adequate technology for wastewater treatment is essential to guarantee the access of information to the community and ultimately the success of the proposed treatment system. In this context, the present work aimed at the development and construction of wastewater treatment systems with fundamental participation of families of the Rural Settlement Olga Benário, Minas Gerais. The methodology based on research-action was used in order to approximate the research to the community needs. The wastewater treatment plants were composed of two units: evapo-transpirator tank and constructed wetland used for black and grey water treatment, respectively. The plants used for the evapo-transpiration tanks were banana-nanica (Musa paradisiaca) and taioba (Xanthosoma sagittifolium (L.) Schott). The plants used in the wetland units were lirio do brejo (Hedychium coronarium). They were built in three households, in a dynamic self-managed collective effort. The systems were monitored physical-chemical and microbiological analyses. The evapo-transpirator tanks achieved efficiencies above 90%, in terms of turbidity, COD, BOD5, TSS, VSS and FSS removals. The vegetation used in the evapotranspirator tank had a desirable development and absence of total coliforms and E. coli. in analyzes performed on the cocoyam´s leaves and stems. The constructed wetlands achieved a satisfactory performance in the grey water treatment, obtaining an organic matter removal average above 80%, reaching 86% and 88% for COD and BOD, respectively. In terms of suspended solids, the treated wastewater showed a concentration in a range of 19 and 37 mg.L-1. / No Brasil, o saneamento básico em zonas rurais encontra-se ainda em situação precária, sobretudo em relação ao tratamento do esgoto domestico, expondo as famílias a focos de contaminação. A participação das comunidades rurais no processo decisório para a escolha das tecnologias de tratamento torna-se essencial para o acesso às informações e o sucesso dos sistemas a serem implantados. Neste contexto, este trabalho foi realizado com o objetivo de conceber e construir, de forma participativa com famílias do assentamento rural Olga Benário, MG, sistemas de tratamento de esgoto mais apropriados à realidade local. No que se refere ao tratamento de efluentes domésticos, destaca-se a gravidade da realidade das famílias, principalmente, nas zonas rurais, onde a situação de saneamento é precária, as quais ficam constantemente sujeitas e vulneráveis a focos de contaminação. A participação da comunidade no processo decisório para a escolha das tecnologias de tratamento é de suma importância para garantir o acesso às informações e a indissociabilidade entre o usuário e o produto. A metodologia com base na pesquisa-ação foi utilizada de forma a aproximar a pesquisa aos anseios da comunidade. O sistema de tratamento de esgoto domestico, composto de duas unidades: tanque de evapotranspiração e wetland construído, foi selecionado para o tratamento de águas negra e cinzas, respectivamente, e construído em três residências do assentamento pelos próprios moradores. A vegetação utilizada no tanque de evapotranspiração foi banana-nanica (Musa paradisiaca) e taioba (Xanthosoma sagittifolium (L.) Schott) e na unidade wetland construída foi lírio do brejo (Hedychium coronarium). Os sistemas foram monitorados em diversos parâmetros físicos, químicos e microbiológicos. As unidades de evapotranspiração alcançaram eficiências médias acima de 90%, em termos de remoção de turbidez, DQO, DBO5, SST, SSD, SSV e SSF, obtendo desenvolvimento foliar desejável e ausência de coliformes totais e E. coli em análises realizadas nas folhas e talos das taiobas. As unidades wetland construídos obtiveram bom desempenho no tratamento de águas cinzas com remoções médias de 86% e 88% para DQO e DBO5, respectivamente, e concentrações de sólidos suspensos totais no efluente variando de 19 e 37 mg.L-1 .

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