Rozprawy doktorskie na temat „Eutrophication – Control”
Utwórz poprawne odniesienie w stylach APA, MLA, Chicago, Harvard i wielu innych
Sprawdź 37 najlepszych rozpraw doktorskich naukowych na temat „Eutrophication – Control”.
Przycisk „Dodaj do bibliografii” jest dostępny obok każdej pracy w bibliografii. Użyj go – a my automatycznie utworzymy odniesienie bibliograficzne do wybranej pracy w stylu cytowania, którego potrzebujesz: APA, MLA, Harvard, Chicago, Vancouver itp.
Możesz również pobrać pełny tekst publikacji naukowej w formacie „.pdf” i przeczytać adnotację do pracy online, jeśli odpowiednie parametry są dostępne w metadanych.
Przeglądaj rozprawy doktorskie z różnych dziedzin i twórz odpowiednie bibliografie.
Tuzun, Ilhami. "Eutrophication and its control by biomanipulation". Thesis, University of Essex, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386919.
Pełny tekst źródłaSchneider, Jana. "Biomanipulation for eutrophication control in running waters". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-198843.
Pełny tekst źródłaLukhele, Nomagugu Precious. "Site-specific environmental risk assessment for phosphorus runoff". Thesis, University of Limpopo, 2014. http://hdl.handle.net/10386/1291.
Pełny tekst źródłaPhosphorus (P) runoff from agricultural sites and the subsequent loading into surface water bodies contribute to eutrophication. Environmental concerns associated with P loading in soil have motivated the need for the development of a proper tool that will allow farmers to identify agricultural areas or management practices that have the greatest potential to accelerate eutrophication. The objective of the study was to determine the spatial variability of soil test P, soil loss potential of the farm, P application rate and methods, and map P runoff risk across the field. This study was conducted in Vierfontein Boerdery in Kriel, Mpumalanga province, South Africa (longitude 29.11258833 and latitude -26.27104340). The field was under dryland cultivation and planted to yellow maize that was rotated with soybeans. Soil samples were taken at georeferenced locations in a 100 x 100 m grid for soil analysis. Spatial layers of soil P distribution, soil loss potential as well as application rate and method were created in ArcGIS software. These layers were used as input factors in a P index model to identify areas in the farm that are vulnerable to P runoff. Results indicated a variation in soil test P. Although soil test P variation was not statistically different at P≤0.05, variation had both agronomic and environmental implications. This variation could be attributed to differences in site-specific conditions and management practices. Furthermore, soil loss potential across the study site predicted by the Revised Universal Soil Loss Equation (RUSLE) showed variation with a range of 3-15 tons/ha/yr. This variation was attributed to differences in topographic variations in the study site. There is a need for best management practices that control soil erosion to minimize P runoff into water bodies. KEYWORDS: Eutrophication, Geographic Information System, Phosphorus best management practises, Phosphorus runoff index, Soil erosion, Site-specific management.
Bohman, Brita. "Transboundary Law for Social-Ecological Resilience? : A Study on Eutrophication in the Baltic Sea Area". Doctoral thesis, Stockholms universitet, Juridiska institutionen, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-137829.
Pełny tekst źródłaBaltic Ecosystem Adaptive Management, BEAM
Paulsen, Sandra Silva. "Topics on the ecological economics of coastal zones : linking land uses, marine eutrophication, and fisheries /". Uppsala : Dept. of Economics, Swedish University of Agricultural Sciences, 2007. http://epsilon.slu.se/200773.pdf.
Pełny tekst źródłaSilva, Andrievisk Gaudencio Pereira e. "O que controla o crescimento do Fitopl?ncton em lagoas costeiras tropicais? um modelo para a lagoa de Extremoz (RN)". Universidade Federal do Rio Grande do Norte, 2014. http://repositorio.ufrn.br:8080/jspui/handle/123456789/16008.
Pełny tekst źródłaCoordena??o de Aperfei?oamento de Pessoal de N?vel Superior
The phytoplankton growth is dependent of several abiotic (nutrients, temperature) and biotic (predation by zooplankton) variables. In this work, a mathematical model was developed in Stella software to understand the planktonic dynamics of Extremoz Lagoon (RN) and to simulate scenarios of different environmental conditions. Data were collected monthly at two points of the lagoon. The state variables are phytoplankton and zooplankton and forcing variables are nitrogen, phosphorus and temperature. The results show that: a) the model are well coupled, especially when some constants assume different values; b) simulated nutrient concentrations reduction decreases phytoplankton biomass, but the increase of nutrients does not stimulate the growth; c) changes in the temperature does not change the phytoplankton biomass; d) changes in zooplankton biomass affect directly and reduces the phytoplankton, indicating a topdown control mechanism; e) changes in the nutrient concentration modified the biomass of zooplankton suggesting a rapid flow of energy between nutrients, phytoplankton and zooplankton and a ecosystem likely arranged in an inverted pyramid (higher concentration of zooplankton than phytoplankton)
O crescimento fitoplanct?nico ? dependente de uma s?rie de vari?veis abi?ticas (nutrientes, temperatura, luz) e bi?ticas (preda??o por zoopl?ncton e outros fitoplanct?fagos, bact?rias que provocam lise celular no fitopl?ncton). Neste trabalho, um modelo de compartimentos foi desenvolvido no software Stella para entender a din?mica planct?nica da Lagoa de Extremoz (RN) e simular diferentes cen?rios de altera??es em importantes vari?veis ambientais como fitopl?ncton e zoopl?ncton. As medi??es foram realizadas mensalmente em dois pontos da lagoa. As vari?veis de estado s?o fitopl?ncton e zoopl?ncton e as for?antes s?o nitrog?nio, f?sforo e temperatura. Os resultados mostram que: a) o modelo se ajusta bem aos dados, especialmente quando algumas constantes assumem diferentes valores; b) simula??es de redu??es das concentra??es de nutrientes diminuem a biomassa fitoplanct?nica, mas o aumento dos nutrientes n?o favorece o crescimento; c) altera??es na temperatura n?o modificam a biomassa fitoplanct?nica; d) modifica??es na biomassa de zoopl?ncton afetam diretamente e consideravelmente o fitopl?ncton, indicando um mecanismo de controle top-down; e) altera??es nas concentra??es de nutrientes modificam a biomassa do zoopl?ncton sugerindo um r?pido fluxo de energia entre nutrientes, fito e zoopl?ncton e um prov?vel ecossistema arranjado em pir?mide invertida (maior biomassa de zoopl?ncton do que fitopl?ncton)
Castejón, Silvo Inés. "Grazing on the epiphytic community of Posidonia oceanica (L.)Delile: An assessment of its relevance as a buffering process of eutrophication effects". Doctoral thesis, Universitat de les Illes Balears, 2011. http://hdl.handle.net/10803/84146.
Pełny tekst źródłaBonaglia, Stefano. "Control factors of the marine nitrogen cycle : The role of meiofauna, macrofauna, oxygen and aggregates". Doctoral thesis, Stockholms universitet, Institutionen för geologiska vetenskaper, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-115036.
Pełny tekst źródłaAt the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 2: Manuscript.
Brady, Mark. "Managing agriculture and water quality : four essays on the control of large-scale nitrogen pollution /". Uppsala : Dept. of Economics, Swedish Univ. of Agricultural Sciences, 2003. http://epsilon.slu.se/a369-ab.html.
Pełny tekst źródłaAlly, Sayed Hanief. "An investigation into the effect of climate change on eutrophication and surface water quality of Voelvlei Dam with an emphasis on algal growth". Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/80109.
Pełny tekst źródłaENGLISH ABSTRACT: The study of climate change and its effect on the eutrophication of surface waters is a current and critically important study for the well-being of the entire planet. Within the same emission scenario various probable climate change models outcomes are possible that affect the water quality of a body of water. Voëlvlei is an off-channel dam that supplies water to the city of Cape Town in the Western Cape Province of South Africa. Historically, it is a eutrophic dam and with climate change, its water quality is expected to worsen. Four statistically downscaled climate models are used to produce meteorological outputs that drive the hydrodynamic and water quality model. The times simulated were the present day (1971-1990), the intermediate future (2046-2065) and the distant future (2081-2100). The operating procedure was not expected to change for the dam and inflows and withdrawals were kept the same for each of the simulation periods. The water quality model CE-QUAL-W2 version 3.6 was used. The bathymetry was validated with measured data. The model was calibrated for temperature, phosphorus loading, ammonium, nitrite-nitrates and chlorophyll-a concentration. The model was used to predict a present day situation in the dam, which was the basis from which future changes would be assessed. The main driver for algal growth other than nutrients and light was water temperature, which was linked to air temperature. With climate change, the air temperature will raise and enhance algal growth. The limiting nutrient was phosphorus during the winter and the rest of the year nitrogen limits algal growth. In the present day, the dominant algal group was the green algae. With climate change an increase in the surface water temperature will increase evaporation and cause a decrease in the yield of the dam and further concentrates the algal nutrients. The surface phosphates concentration show increases in all months but especially in autumn. The total algal growth was increased annually and especially during autumn, signalling a seasonal shift and lengthening of the bloom season. The dominant algae however are still the green algae. There will be an increase in the annual concentration of diatoms. The green algae are present in the highest concentrations when compared to diatoms and cyanobacteria. The increase in its nutrients throughout the year as well as the increased water temperature allowed for unabated growth the entire year with peaks earlier in the year during autumn. Cyanobacteria are present at the surface for the entire year at significant concentrations but with intermediate and future climate change their concentrations does not change significantly. The result for cyanobacteria was inconclusive as the inter-variability between the climate models has the greatest variability for cyanobacteria, with 2 models showing an increased concentration and 2 a decreased concentration for intermediate and future time-period. For climate change, the water quality worsens especially during winter. With climate change water quality will worsen earlier in the year confirming a seasonal shift. The modelling of dissolved oxygen proved daunting as the results indicated supersaturation. The concentration of dissolved oxygen does not vary much as would be expected due to the warmer waters.
AFRIKAANSE OPSOMMING: Die studie van klimaatsverandering en die uitwerking daarvan op die eutrofiseering van die oppervlaktewater is 'n huidige en krities belangrike studie vir die welsyn van die hele planeet. Binne dieselfde emissie scenario, is verskeie moontlike uitkomste van klimaat modelle moontlik en die invloed op die kwaliteit van die oppervlakwater. Voëlvlei is 'n buite-bedding dam wat water verskaf aan die stad van Kaapstad in die Westelike Provinsie van Suid-Afrika. Histories is dit is 'n eutrofiese dam en met die verandering van die klimaat sal die kwaliteit van die water na verwagting verswak. Vier statisties afgeskaal klimaat modelle word gebruik om meterologiese toesttande te skep en hiedie word dan gebruik as invoer vir die hidrologiese and water kwaliteits model vir die huidige situasie (1971-1990), die intermediêre toekoms (2046-2065) en die verre toekoms (2081-2100). Die bedruifs-proses vir die dam was nie verwag om te verander nie en die invloei en onttrekkings was dieselfde gehou vir elk van die simulasie periodes. Die watergehalte model CE-QUAL-W2 3.6 was gebruik. Die bathymetrie was bevestig met gemete data. Die model was gekalibreer vir temperatuur, fosfor, ammonium, nitriet-nitrate en chlorofil-a konsentrasie. Die model was gebruik om 'n huidige situasie in die dam te simuleer, wat die basis vir klimaatsveranderinge sou wees. Die vernaamste aandrywer vir die alge groei anders as voedingstowwe en lig, was water temperatuur, wat met lugtemperatuur gekoppel was. Met klimaatsverandering word die lugtemperatuur verhoog en alge groei. Die beperkende voedingstof was fosfor gedurende die winter en die res van die jaar was die dam stikstof beperk. Die dominante alge-groep in die huidige situasie was die groen alge. Met klimaatsverandering stuig die temperatuur van die oppervlakwater, verhoog verdamping, veroorsaak afname in die vlak van die dam en verhoog die konsentrasie van die alge voedingstowwe. Die oppervlak fosfate konsentrasie verhoog in al die maande veral in die herfs. Die totale alge groei jaarliks en veral gedurende die herfs, 'n teken van 'n seisoenale verskuiwing en verlenging van die blom seisoen. Die dominante alge was nog steeds groen alge. Daar sal 'n toename in die jaarlikse konsentrasie van diatome wees. Die groen alge is in die hoogste konsentrasies vergelyk met diatome en sianobakterieë. Die toename in die voedingstowwe deur die loop van die jaar, sowel as die verhoogde watertemperatuur kan vir 'n onverpoos groei vir die hele jaar, veral in die herfs. Sianobakterieë is teenwoordig vir die hele jaar op beduidende konsentrasies, maar met intermediêre en toekomstige klimaat verander die konsentrasies nie veel nie. Die resultaat vir sianobakterieë was onoortuigend as gevolg van die inter-veranderlikheid tussen die klimaats modelle, met 2 modelle wat 'n toename in konsentrasie voorspel en 2 'n afname in konsentrasie voorspel. Vir klimaatsverandering, die kwaliteit van die water vererger veral in die winter. Met klimaatsverandering skyf hierdie verswakking van water kwaliteit na vroeër in die jaar, wat bevestig 'n seisoenale skui vir verergering. Die modellering van opgeloste suurstof was uitdagende en die resultate was super-versadig. Die konsentrasie van opgeloste suurstof wissel nie veel as wat verwag sou word as gevolg van die warmer water.
Schneider, Jana [Verfasser], Carola [Akademischer Betreuer] Winkelmann, Thomas U. [Akademischer Betreuer] Berendonk, Dietrich [Akademischer Betreuer] Borchardt i Alexandra [Akademischer Betreuer] Kroll. "Biomanipulation for eutrophication control in running waters : Top-down effects on benthic key stone grazers / Jana Schneider. Betreuer: Carola Winkelmann. Gutachter: Thomas U. Berendonk ; Dietrich Borchardt ; Alexandra Kroll". Dresden : Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://d-nb.info/1093412348/34.
Pełny tekst źródłaScharin, Henrik. "Management of eutrophicated coastal zones : the quest for an optimal policy under spatial heterogeneity /". Uppsala : Dept. of Economics, Swedish Univ. of Agricultural Sciences, 2004. http://epsilon.slu.se/a503.pdf.
Pełny tekst źródłaGerke, Madlen [Verfasser], Carola [Gutachter] Winkelmann, Jost [Gutachter] Borcherding i René [Gutachter] Sahm. "Biomanipulation in running waters : The potential for top-down control by cypriniform fish in mitigating eutrophication effects in medium-sized rivers / Madlen Gerke ; Gutachter: Carola Winkelmann, Jost Borcherding, René Sahm". Koblenz, 2021. http://d-nb.info/1239648413/34.
Pełny tekst źródłaCaen, Auguste. "Vers la gestion viable de systèmes dynamiques lacustres anthropisés". Thesis, Université Clermont Auvergne (2017-2020), 2019. http://www.theses.fr/2019CLFAC073.
Pełny tekst źródłaAs a consequence of human activities, particularly agricultural activities, lake systems are subject tosignificant nutrient inputs. This phenomenon, called eutrophication, leads to a proliferation of cyanobacteria. This proliferation is an ecological issue, since it causes an imbalance in the lake ecosystem, but also a health issue, since some of the most common species of cyanobacteria can produce toxins. Finally, eutrophication is also an economic issue, since the lakes concerned cannot be exploited. Understanding the phenomena governing the mechanisms linked to eutrophication is therefore essential, on the one hand to anticipate the consequences, and on the other hand to set up policies for the management of eutrophic lake systems. In this thesis, we analyse these phenomena via dynamic models. The study of eutrophication then requires the mathematical study of these models. As an introduction, we present the different criteria studied to evaluate the general state of alake environment. We also present the various existing models. This analysis allows us to select a modeling approach which consists in aggregating the existing variables and phenomena through abstract mathematical laws. The interest of such models is that they considerably reduce the dimension of the studied system and thus require a reduced number of data to be calibrated. Moreover, such models can be analysed with an analytical study of their mathematical properties.Our study consists of three main axes. The first presents the analysis of toxic and non-toxic cyanobacterial populations. Indeed, the toxicity of cyanobacterial blooms is the main health issue oflake eutrophication. However, there are currently no tools to anticipate this toxicity. Although some of the most common species may produce such toxins, not all individuals of the same species are capable of doing so: it depends on the genetic properties of each individual. Thus, two sub-populations within a species must be considered: one toxic, able to produce such toxins, and one non-toxic. The study of the dynamics of toxic populations is therefore essential to anticipate the toxicity of cyanobacterial proliferation. However, analysis of real cases shows that the proliferationsof toxic and non-toxic populations do not occur at the same time, which implies that their dynamics are governed by different laws. In order to describe the dynamics of these toxic and non-toxic subpopulations, we focus on the impact of temperature on their dynamics, which is assumed as one of the parameters governing the toxicity of cyanobacterial blooms. Analysing a model that uses competition between toxic and non-toxic populations and links their dynamics to temperature, we show that seasonal variations in temperature provide an explanation for the observed temporal distribution of toxic and non-toxic populations. We validate these theoretical results through the implementation of an experiment in a controlled environment, and through the analysis of real cases.This first analysis thus provides us with elements of understanding of the phenomena governing the toxicity of cynanobacterial proliferation. The second part of this thesis focuses on strategies for the mitigation of eutrophication in lakes. We no longer focuse on the toxicity of cyanobacterial blooms, but on the dynamics of nutrients, particularly phosphorus. The first way to reduce this phosphorus concentration is to change agricultural policies upstream of the lakes. In addition to these phosphorus emission reductions, some lakes have retention structures. These structures are between the lake and its watershed, and their role is to retain some of the incoming nutrients. Currently, thesestructures are evaluated on their retention capacity alone, and their effects on downstream lake dynamics are not analyzed. This is the subject of this second chapter of the thesis. (...)
Miranda, Marcela Aparecida Campos Neves. "Medidas de mitigação para controle e manejo das florações de cianobactérias em um sistema raso tropical". Universidade Federal de Juiz de Fora (UFJF), 2017. https://repositorio.ufjf.br/jspui/handle/ufjf/6500.
Pełny tekst źródłaApproved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2018-03-27T13:52:08Z (GMT) No. of bitstreams: 0
Made available in DSpace on 2018-03-27T13:52:08Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-06-30
Florações de cianobactérias são consequência principalmente da eutrofização de ambientes aquáticos que afeta a qualidade e compromete o uso da água para diversas finalidades. A restauração de sistemas aquáticos eutrofizados é um dos principais desafios da limnologia atual. Nosso objetivo foi identificar as principais causas do processo de eutrofização e ocorrência de florações de cianobactérias e testar a eficácia e aplicabilidade do uso combinado de coagulantes e adsorventes de P em fase sólida no controle da eutrofização e florações em um lago tropical raso. O estudo foi conduzido no lago do Museu Mariano Procópio, localizado em Juiz de Fora – MG e dividido em quatro fases. As duas primeiras fases compreendem uma análise sistêmica do lago. Na primeira, buscou-se conhecer a dinâmica da comunidade fitoplanctônica a fim de entender a dominância de cianobactéria deste sistema. Na segunda, foram avaliados os aportes de fósforo (P) para o sistema. Na terceira fase foram realizados experimentos em laboratório, para verificar a eficácia de diferentes coagulantes e lastros para remoção de cianobactérias. E na quarta fase foram realizados experimentos em mesocosmos no lago, para testar o controle da eutrofização e florações de cianobactérias. A análise sistêmica mostrou dominância de diferentes espécies de cianobactérias e que as altas concentrações de nutrientes presentes do sistema vêm principalmente de contribuição externa. O uso combinado de coagulantes e lastros foi eficiente para a remoção de biomassa de cianobactérias, porém foi dependente da espécie. Nos experimentos com mesocosmos, foi observada uma forte redução de Clorofila a (Chl a 85%) e fósforo total (TP 78%) (p <0,0010) em todos os tratamentos, porém estas reduções não se mantiveram ao longo do tempo. Para mitigar as florações de cianobactérias deste sistema, será necessário o controle das fontes externas de nutrientes e um ajuste na técnica de coagulante-lastro para manter a clorofila e o fósforo total em concentrações reduzidas por mais tempo.
Cyanobacterial Blooms are mainly a consequence of eutrophication of aquatic environments that affect the water quality and compromise the use of water for various purposes. The restoration of eutrophic aquatic systems is one of the main challenges of today's limnology. Our objective was to identify the main causes of the eutrophication process and the occurrence of cyanobacterial blooms in a shallow tropical lake, and to test the efficacy and applicability of the combined use of coagulants and adsorbents of P in solid phase for the control of eutrophication and cyanobacteria blooms in a tropical shallow system. The study was conducted in the lake of the Mariano Procópio Museum, located in Juiz de Fora - MG and divided into four phases. The first two phases comprised a systemic analysis of the lake. The first one sought to know the dynamics of the phytoplankton community and to understand the causes of the cyanobacteria dominance in this system. In the second one, the main contributions of phosphorus to the system and the general balance of P were evaluated. In the third phase, laboratory experiments were carried out to evaluate the efficacy of different coagulants and ballasts for the removal of cyanobacteria. Last, in the fourth phase experiments were carried out in mesocosmos in the lake to test the control of eutrophication and cyanobacterial blooms. The systemic analysis showed the dominance of different species of cyanobacteria and that the high concentrations of nutrients present in the system come mainly from external contribution. The combined use of coagulants and ballasts was efficient for the removal of cyanobacteria biomass, but it is dependent on the species pool. In the experiments with mesocosms, a strong reductions of chloropyll a (Chl a) 85% and total phosphorus (TP) 78% (p < 0.001) were observed in all treatments, however these reductions were not lasting. To mitigate the cyanobacterial blooms of this system, it will be necessary to control the external sources of nutrients and also an adjustment in the coagulant-ballast technique to keep Chl a l and TP in reduced concentrations for longer time.
Zhang, Zhenhua. "Plant growth and nutrient removal in simulated secondary-treated municipal wastewater in wetland microcosmos". University of Western Australia. School of Earth and Geographical Sciences, 2008. http://theses.library.uwa.edu.au/adt-WU2008.0141.
Pełny tekst źródłaMcLenaghan, Natalie Ann. "Benthic macroinvertebrate diversity in a shallow estuary : controls on nutrient and algal dynamics /". Online version of thesis, 2009. http://hdl.handle.net/1850/9704.
Pełny tekst źródłaOzen, Arda. "Impact Of Top Down And Bottom Up Controls On The Microbial Loop In Turkish Shallow Lakes: Space For Time Substitute, Monitoring And Mesocosms Approaches". Phd thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12615058/index.pdf.
Pełny tekst źródłaCastro-Castellon, Ana. "A biofilter process for phytoplankton removal prior to potable water treatment works : a field and laboratory study". Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:9ac04284-cf4a-48f1-bdab-d8ca6e66aefb.
Pełny tekst źródłaMoussoh, Amahoué François. "Simulation de l’écoulement par des approches de Mécanique des Fluides Numérique et évaluation de la dispersion de principes actifs utilisés pour traiter les plans d’eau eutrophisés". Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0062.
Pełny tekst źródłaThis work is part of an overall project to develop an innovative process for targeted treatment of invasive aquatic plants in a lentic water body. One of the challenges is to optimize the concentration of active substance required to remove the target plants without creating potential ecological damage. A methodology based on a bottom-up modeling approach was applied using Computational Fluid Dynamics (CFD) in order to define optimal conditions for effective treatment. This modeling approach was used for the flow and the dispersion of active substance simulations from a 1 m3 pilot to lentic water bodies fed by surface water or groundwater. Five turbulence models were preselected in order to assess their influence on the simulation results. The RNG k-ε model was selected after final validation by tracer experiments at pilot scale mimicking the hydrodynamics of a real lentic water bodies. Experimental measurements on pilot and numerical simulations carried out on scale thereof with four configurations of lentic water bodies have allowed to evaluate the impact of several hydrodynamic parameters (water flow, number of inlets and outlets, type of water supply, …) and external forcing (wind, temperature) on maintaining of algaecide concentration during the treatment. The wind mainly acts as a natural diffuser causing 95% of diluting the algaecide concentration. Taking account of the rate of chemical reaction of the active substance in water also indicates a decrease of the local concentration of active substance. The optimal treatment is not only based to the control of injected concentration but it is also related to a good understanding of the local water flow
Wu, Ming-Chuan, i 吳銘圳. "Optimal Control of Eutrophication for a Reservoir". Thesis, 1997. http://ndltd.ncl.edu.tw/handle/40471640058678814430.
Pełny tekst źródłaTsai, Yuan-Yao, i 蔡元堯. "Biological control of eutrophication in a coastal lagoon". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/11729095342104067572.
Pełny tekst źródła國立東華大學
海洋生物多樣性及演化研究所
102
Excessive levels of nutrients and trace contaminants in seawater can lead to algal blooms, including red tides. Algal blooms and red tides in particular are detrimental to marine ecosystems and fisheries, and can additionally generate human health concerns. Herein seawater quality parameters, including chlorophyll a (chl-a) concentration and nutrient levels, were measured at Tapong Bay, Southern Taiwan. Additionally, experiments were designed in order to determine the effects of elevated nitrogen and phosphorus levels on algal growth. Some of these laboratory incubations were conducted with oysters of varying densities in order to determine how these bivalves influence seawater quality. Briefly, it was hypothesized that certain oyster densities may prevent algal blooms due to their ability to sequester nutrients from the seawater, and thus serve as environmental bioremediators. The results of these studies show that land-based pollution, coupled with early spring rains, can indeed lead to red tide formation in Tapong Bay. There was a negative associations between chl-a concentration and dissolved inorganic nitrogen (DIN) concentration in situ, though a positive correlation between chl-a concentration and dissolved inorganic phosphorus (DIP); these observations may be due to nitrogen absorption by phytoplankton. During the winter, vertical mixing brings benthos-entrenched nutrients to the surface, yet no red tides occurred at this time. This suggests that additional biolimiting factors must act in concert with nutrient levels to control such algal blooms. Collectively, our results show that nitrogen is the main nutrient associated with algae blooms, meaning that nitrogen levels must be better controlled. At a mean mariculture density of 75 individuals/m3, oysters were able to remove 23.4 % nitrogen and 8.6 % phosphate daily to minimize blooms occurrence. According to this culture condition, it is estimated that the annual removal from lagoon is about 267.9t for nitrogen and 38.6t for phosphorus.
Lee, Wei-min, i 李維民. "Biomanipulation in an Artificial Pond for Eutrophication Control". Thesis, 2008. http://ndltd.ncl.edu.tw/handle/41355258071923644745.
Pełny tekst źródła國立臺灣大學
環境工程學研究所
96
The high concentration of algae in water body is the most significant symptom of eutrophication and often perplexes the users of the water. With the approach of biomanipulation, we built several artificial refuges made of plastic net for zooplankton in an artificial pond. We wanted to reduce the quantity of algae in the water by the enhanced consumption of zooplankton due to their increased population. These refuges could offer safe habitats for zooplankton to hide and increase the space heterogeneity in the pond. The results of our research indicate that the species diversity of zooplankton in the refuges has increased due to the appearance of rotifers and protozoa. But the amount of zooplankton was still low in open water outside the refuges. Without large body-sized zooplankton in the water in this case, the concentration of algae in the pond remained high after the installation of the refuges.
Martins, Gilberto. "Eutrophication-threatened aquatic ecosystems: sediment biogeochemical processes towards nutrients control". Doctoral thesis, 2011. http://hdl.handle.net/1822/12500.
Pełny tekst źródłaEutrophication is the most common reason for lake management and results mainly from anthropogenic activities occurring in their watersheds. Nowadays, eutrophication is also due to internal inputs of phosphorus (P), as is the case of Azoreans lakes. P tends to accumulate in lake sediments leading to an excess of P in the water column and the concomitant proliferation of planktonic algae. In Azores, despite the considerable effort made to describe the phytoplankton growing on the water column, the lack of information regarding the microbial processes in sediments is still high. In that regard, the present work aims to assess the sediment reference conditions (e.g. biogeochemical composition of sediments) of Azorean lakes in order to incorporate sediment issues and knowledge into management strategies enhancing the efficacy of the remediation activities that should be taken to achieve the good ecological status until 2015. Sediment samples were collected and biogeochemical profiles, organic matter (OM), total nitrogen, TP and total iron (TFe), were determined. Lake Azul profiles were quite homogeneous for all parameters, while in lake Furnas TFe profile presented a peak below the aerobic layer. For lake Verde, the concentration of all studied elements (20±2 % OM; 2.10±0.08 mg/g TP; 1.31±0.50 mg/g TN; 8.06±0.13 mg/g TFe) in the uppermost sediment layer was approximately two times higher than the ones in sediments from other lakes, decreasing with sediment depth. The higher amounts of P and OM in lake Verde suggested a higher internal contribution of P to eutrophication. Dominant members were mostly affiliated to Proteobacteria phylum (Alpha-, Delta-, and Gamma-subclasses), group Bacteroidetes/Chlorobi and phylum Chloroflexi. The Cyanobacteria phylum was solely detected in sediments from lake Verde and lake Furnas that presented the highest amounts of N and P both in the water column and sediments, while the other phyla were detected in sediments from the three studied lakes. The combination of quantitative PCR and activity tests suggested that bacteria performing ammonium oxidation (aerobic and anaerobic), nitrite oxidation, heterotrophic nitrate reduction, iron reduction and biological P storage/release were present and active in sediments. Bacteria performing anaerobic ammonium oxidation were the most abundant in sediments from the eutrophic lakes Verde, Azul and Furnas (4.5 % to 16.6 %), followed by nitrifying bacteria (0.8 % to 13.0 %), denitrifying bacteria (0.5 to 6.8 %), iron-reducing bacteria of the Geobacteraceae family (0.2 % to 1.4 %), and phosphorus-accumulating organisms affiliated to Candidatus Accumulibacter (less than 0.3 %). In opposition, denitrifying bacteria dominated in sediments from the oligo-mesotrophic lake Fogo (8.8 %). Lake Furnas sediments presented bacterial stratification (aerobes in upper layers and anaerobes downward) due to the presence oxygen in the hypolimnion all year round. The present work also suggested that biological phosphorus storage/release by denitrifying bacteria in sediments might as well contribute to the release of P from sediments. Moreover, lake Furnas sediment bacterial community was electroactive as demonstrated both by cyclic voltammetry and power generation in a simulated benthic microbial fuel cell.Martins G. 2010 sediments from the eutrophic lakes Verde, Azul and Furnas (4.5 % to 16.6 %), followed by nitrifying bacteria (0.8 % to 13.0 %), denitrifying bacteria (0.5 to 6.8 %), iron-reducing bacteria of the Geobacteraceae family (0.2 % to 1.4 %), and phosphorus-accumulating organisms affiliated to Candidatus Accumulibacter (less than 0.3 %). In opposition, denitrifying bacteria dominated in sediments from the oligo-mesotrophic lake Fogo (8.8 %). Lake Furnas sediments presented bacterial stratification (aerobes in upper layers and anaerobes downward) due to the presence oxygen in the hypolimnion all year round. The present work also suggested that biological phosphorus storage/release by denitrifying bacteria in sediments might as well contribute to the release of P from sediments. Moreover, lake Furnas sediment bacterial community was electroactive as demonstrated both by cyclic voltammetry and power generation in a simulated benthic microbial fuel cell. Finally, a mathematical model for lake Verde water quality was developed and calibrated in order to support the decision making processes in aquatic restoration programmes. Prospective scenarios showed that external measures are not enough to improve water quality in lake Verde (an average concentration of TP of 26 g/L and phytoplankton biomass of 1.4 mg/L could be reached in a 10 years horizon) and that an integrated approach (external and internal measures) need to be designed. In conclusion, the present work suggested that sediment bacteria were active and performed diverse roles on carbon, nutrients and iron cycling. The variability of sediment geochemical profiles as well as the structure and activity of sediment bacterial community indicates that individual lake sediment characterization and site-specific assessments of the efficacy of remediation approaches are required. In this regard, the designing of re-qualification strategies towards the good ecological status prescribed by the Water Framework Directive should include, in addition to the classical procedure, an evaluation of the contribution of biological processes in sediments to the eutrophication problem.
A eutrofização é o motivo mais comum para a necessidade de gestão de lagos e, resulta principalmente de actividades antropogénicas que ocorrem nas bacias hidrográficas. Actualmente, a eutrofização é também devida a entradas internas de fósforo (P). O P tende a acumular-se nos sedimentos, levando a um excesso de P na coluna de água e à consequente proliferação de algas planctónicas. Nos Açores, apesar dos consideráveis esforços para descrever o crescimento do fitoplâncton na coluna de água, a falta de informação relativa aos processos microbianos nos sedimentos é ainda muito elevada. Nesse sentido, o presente trabalho teve como objectivo avaliar as condições de referência dos sedimentos (e.g., a composição biogeoquímica dos sedimentos) dos lagos dos Açores, a fim de incorporar as questões e conhecimento sobre sedimentos nas estratégias de gestão, bem como reforçar a eficácia das actividades de remediação que devem ser tomadas para alcançar o bom estado ecológico até 2015. Nesse sentido, foram recolhidas amostras de sedimentos e os perfis biogeoquímicos, matéria orgânica (OM), azoto total (TN), P total (TP) e ferro total (TFe), foram determinados. Os perfis biogeoquímicos para a lagoa Azul revelaram-se bastante homogéneos para todos os parâmetros determinados, enquanto na lagoa das Furnas, o perfil de TFe apresentou um pico abaixo da camada aeróbia. As maiores quantidades de P e OM na lagoa Verde sugeriram uma maior contribuição interna de P para a eutrofização. Relativamente aos membros dominantes da comunidade bacteriana presente nos sedimentos das lagoas Verde, Azul e Furnas, a sua maioria estava afiliada ao filo Proteobacteria, grupo Bacteroidetes/Chlorobi e filo Chloroflexi. O filo Cyanobacteria foi apenas detectado nos sedimentos das lagoas Verde e Furnas, que correspondem às lagoas com maiores teores de N e P, tanto na coluna de água como nos sedimentos. A combinação do PCR quantitativo com os testes de actividade sugeriu que as bactérias que realizam a oxidação do amónio (aeróbia e anaeróbia), a oxidação do nitrito, a redução heterotrófica de nitrato, a redução de ferro e o armazenamento/libertação biológica de fósforo estavam presentes e activas nos sedimentos. As bactérias anaeróbias oxidantes de amónio foram as mais abundantes nos sedimentos das lagoas eutróficas Verde, Azul e Furnas (4.5 % a 16.6 %), seguidas pelas bactérias nitrificantes (0.8 % a 13.0 %), desnitrificantes (0.5 a 6.8 %), redutoras de ferro da família Geobacteraceae (0.2 % a 1.4 %) e organismos acumuladores de fósforo filiados a “Candidatus Accumulibacter” (<0.3 %). Em oposição, as bacterias desnitrificantes dominaram os sedimentos da lagoa oligo-mesotrófica do Fogo (8.8 %). Os sedimentos da lagoa das Furnas apresentaram estratificação bacteriana (os grupos aeróbios dominaram as camadas superiores e os anaeróbios as camadas mais profundas) devido à presença de oxigénio no hipolímnio durante todo o ano. O presente trabalho também sugeriu que a acumulação/libertação biológica de P pelas bactérias desnitrificantes pode contribuir para a liberação de P dos sedimentos. Além disso, a comunidade bacteriana presente nos sedimentos da lagoa das Furnas apresentou electroactividade como demonstrado tanto por voltametria cíclica como pela produção de energia numa célula de combustível microbiana bêntica.Finalmente, um modelo matemático de qualidade da água da lagoa Verde foi desenvolvido e calibrado de forma a apoiar os processos de decisão em programas de recuperação aquáticos. Os cenários prospectivos mostraram que medidas externas não são suficientes para melhorar a qualidade da água na lagoa Verde (uma concentração média de TP, 26 g/L P e fitoplâncton, 1.4 mg/L, podem ser alcançadas num horizonte de 10 anos) e que uma abordagem integrada (medidas internas e externas) deve ser desenhada. Em conclusão, o presente trabalho sugeriu que as bactérias presentes nos sedimentos desempenham um papel activo no ciclo do carbono, nutrientes e ferro. A variabilidade dos perfis biogeoquímicos nos sedimentos, bem como a estrutura e a actividade da comunidade bacteriana indicaram que uma caracterização individual dos sedimentos dos diferentes lagos e que avaliações específicas da eficácia das medidas de remediação são necessárias. Neste sentido, a concepção de estratégias de requalificação para o bom estado ecológico prescrito pela Directiva Quadro da Água deve incluir, para além do procedimento clássico, uma avaliação da contribuição dos processos biológicos nos sedimentos para o problema da eutrofização.
Fundação para a Ciência e a Tecnologia (FCT) - SFRH/BD/25639/2005
Pocock, Gina. "Phosphorus limitation as a method of cyanobacterial bloom control". Thesis, 2009. http://upetd.up.ac.za/thesis/available/etd-05302009-120841.
Pełny tekst źródłaCHEN, Chun-hung, i 陳圳鴻. "The water quality analysis and the optimal parameters control for eutrophication". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/60217815651586689394.
Pełny tekst źródła弘光科技大學
環境工程研究所
102
In this study, 21 major reservoirs in Taiwan were investigated, including water quality parameters (transparency (SD), water temperature (WT), pH value , dissolved oxygen (DO), chlorophyll a (Chl-a), total phosphorus (TP), total organic carbon (TOC) and total nitrogen (TN)), eutrophic index (Carlson Trophic State Index, CTSI), and multiple regression analysis, whereby the province to identify the main causes of eutrophication of reservoirs. The results showed that low transparency southern reservoirs , high water temperature, low dissolved oxygen , chlorophyll a higher nutrient ( phosphorus , carbon, nitrogen ) were the highest , resulting in the highest value of CTSI Reservoir in southern province , also cause eutrophication of reservoirs in southern main reason. According to the study of methods to control eutrophication that found to reduce phosphorus discharged into the reservoir is the best control strategy, this method would be reduced the reproduction rate of algae , to avoid the deterioration of water quality. Moreover, the situation in Southern Taiwan reservoirs, some reservoirs in nearly a decade of statistics showing a slowing trend in Lantan reservoir and reservoir Agongdian more significant, mainly because of the nutrient phosphorus, carbon and nitrogen are reduced year by year due to , and by the transparency (SD) data discovery reservoir gradually becomes clear, and chlorophyll a (Chl-a) significantly dropped significantly, which is to reduce the concentration of algae. Emerald another reservoir in northern CTSI value increased in recent years, the phenomenon has a tendency, judged mainly due to an increase in water and nutrient phosphorus trend. The results of this study may suggest eutrophication province have advised against the tendency of the reservoir of nutrients into the conduct of the watershed control, including the planting of crops should be counseling their correct fertilization or fallow, especially for the small amount of phosphorus control, must also there are elaborate plans to avoid drinking water suffer algal blooms, and even lead to safety concerns public water algae poison. Keywords: reservoir, eutrophication, Carlson trophic state index, algae, chlorophyll a, nutrients
Chuang, Tzu-Wang, i 莊子旺. "The development and application of an optimization model for reservoir eutrophication control". Thesis, 1998. http://ndltd.ncl.edu.tw/handle/12338512212139657727.
Pełny tekst źródła國立臺灣大學
土木工程學系研究所
86
The purpose of this thesis is to develop an optimization model for reservoir eutrophication control, using DDP ( Dynamic Differential Programming)as the optimization method to solve the problem, and taking Feitsui Reservoir as our example. The objective function of this model is the minimum needed pollution reorganization scale. The constraints of water quality model is an equality, along with a physical inequality constraint. This research employs the zero- dimensional water quality model, considering six water quality variables. The biochemical reaction equation is nonlinear. When considering time-variant factors, the model is dynamic and unsteady. The results of the optimization enables us to find the necessary efficiency to deal with the pollution sources, in order to keep the "chlorophyll-a" consistency within the lake under a certain level. Since the model is time-variant, the resulting control project is a function of time, and is adaptable and able to make economical as well as effective arrangements. This research adopts the DDP method to solve optimization problems of dynamic eutrophication control. The results show the feasibility of this optimization method as a way to solve dynamic reservoir eutrophication control problems.
Hsu, Chia-Chen, i 許嘉珍. "The Algal Ecological Modeling in Hsin-shan Reservoir and Preliminary Study in Eutrophication Control". Thesis, 2006. http://ndltd.ncl.edu.tw/handle/06015606377878611261.
Pełny tekst źródła國立臺灣大學
環境工程學研究所
94
Hsin shan reservoir is located in Keelung, Taiwan. By sampling during last year, we collected the water quality data of this reservoir, including algae phase and nutrient such as ammonia nitrogen, nitrate and phosphate. These data were used in developing an algae dynamic model which is zero dimension. From surface to ten meters down to the water, we divided three levels to simulate the growth situation of different kinds of algae. The measured data showed that there was a phenomenon about algae succession happened in this reservoir. The physical characteristics of different kind algae and the environmental condition controlled which kind of algae would be the widely distributed species. Take Hsin Shan reservoir for example, Cyanophyta had a wide distribution in summer, but in fall, Bacillariophyta and Chrysophyta replaced it. After calculating all parameters of this model, other data were needed to verify the model. This model can also be used for environmental management, and to predict when bloom will happen in reservoirs. Eutrophication is a serious problem in reservoirs, and Hsin shan reservoir was examined beyond standard in 2003 with Carlson Index. In order to correct this, we established a pilot in this reservoir. In the pilot, mixing was thought to destratify the stable condition of water. In the end of the experiment, the goal species, Microcystis, didn’t leave the water body. The possible reason was that the environment below the surface water was also suitable for it, and there might be enough light and nutrient for its growth. More powerful mixing or other artificial methods are needed to alleviate the bloom happened in Hsin shan reservoir.
Li, Guiyou. "The role of iron in the control of noxious, bloom forming cyanobacteria in productive and unproductive waters /". 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR38799.
Pełny tekst źródłaTypescript. Includes bibliographical references (leaves 112-121). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR38799
Schneider, Jana. "Biomanipulation for eutrophication control in running waters: Top-down effects on benthic key stone grazers". Doctoral thesis, 2015. https://tud.qucosa.de/id/qucosa%3A29273.
Pełny tekst źródłaCoetzee, Julie A. "The role of eutrophication in the biological control of water hyacinth, Eichhornia crassipes, in South Africa". 2011. http://hdl.handle.net/10962/69263.
Pełny tekst źródłaCha, Yoon Kyung. "Load reduction and invasive mussel effects on eutrophication dynamics in Saginaw Bay, Lake Huron". Diss., 2011. http://hdl.handle.net/10161/5711.
Pełny tekst źródłaPhosphorus load reduction and dreissenid invasion are the two most important factors that influence europhication dynamics in the Great Lakes. The 1978 amendments to the Great Lakes Water Quality Agreement (GLWQA) between the United States and Canada established target phosphorus loads for the lakes, leading to reductions in external phosphorus loading to the Great Lakes. With diminished phosphorus levels, further nutrient management was a minor concern until the proliferation of invasive dreissenid mussels. Dreissenid mussels were first documented in the Laurentian Great Lakes in the late 1980s. Zebra mussels (
This dissertation characterizes long-term patterns of phosphorus loading and mussel populations for Saginaw Bay, and estimates the effects of load reductions and dreissenid invasion on several aspects of pelagic water quality, focusing on phosphorus flux and cycling in Saginaw Bay. Bayesian approaches were used to quantify the impacts of load reduction and mussel invasion, while at the same time addressing model parameter uncertainty and prediction uncertainty associated with long-term observational data. Annual total phosphorus load estimates suggest a decreasing trend until the late 1970s to early 1980s, reflecting the effectiveness of point source controls implemented pursuant to GLWQA. Despite the decrease, however, the annual loads have not likely met the 440 tonne yr-1 target established for Saginaw Bay. In 1990 zebra mussels were discovered in the bay and by 1992 they were widespread and peaked with densities of >30,000 m
Dissertation
Wu, Chien-Chang, i 吳健彰. "Nutrient Loading and Control Strategies for Eutrophication of the Jin-sha and Rong-hu Reservoirs in Kinmen". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/88829103479124951366.
Pełny tekst źródła國立臺灣大學
環境工程學研究所
104
Jin-sha Reservoir and Rong-hu Reservoir in Kinmen County suffer from the problems of high concentration of dissolved organic carbon (DOC) and eutrophication. High DOC in raw water will lower the efficiency of water treatment, cause the production of disinfection byproducts (DBP) in tap water, increase the treating cost and pose risk of cancer to the public. Eutrophication also leads to problems such as high turbidity, low dissolved oxygen, bad odors, etc. Cylindrospermopsis raciborskii, which was thought as a tolerator of high salinity in previous researches, was the dominating species in Jin-sha Reservoir and Rong-hu Reservoir most of the time, This study aimed to find out the correlations between the abundance of Cylindrospermopsis raciborskii and several water quality parameters in the reservoirs as well as the reason for high DOC by investigating physical and chemical characteristics of reservoirs, nutrient loadings from the watersheds , and the algal composition. Sources of saline water that resulted in high salinity and conductivity in these two reservoirs were sought. In addition, this study devoted to develop a new method for estimating the nutrient loadings of the reservoirs, and constructed a model for simulating the concentration of DIN (dissolved inorganic nitrogen ) and DIP (dissolved inorganic phosphorus) in the two reservoirs. In order to control the growth of algae, a device as light-shading board was developed and its performance was evaluated by field test. The results of investigation shows that dominance of Cylindrospermopsis raciborskii does have correlation with the high salinity in the water. Saline water entered through inflow channels of these two reservoirs. Large proportion of dissolved organic carbon in the reservoirs was produced by algae, and the environment with low dissolved inorganic nitrogen (DIN) to dissolved inorganic phosphorus (DIP) ratio and low temperature favored the dominance of Cylindrospermopsis raciborskii. Simulated nutrient concentrations fall in the ranges the same as the real concentrations. Finally, we found that light-shading device would not be effective when shading only 50% of the water surface, and more tests are needed. With all these results, controlling strategies for eutrophication ( Cylindrospermopsis raciborskii ) were figured out: 1. Keeping the water level high to avoid saline water entering Rong-hu Reservoir from the bottom, and using saline groundwater for irrigation should be avoided. 2. building retention pond at the inflow channels of the reservoirs to retain eroded soil as much as possible.
Ruiz, Albizuri José Ricardo. "Effects of Global Warming on Phytoplankton and its Biocontrol in Large Rivers: Insights from a Model Analysis". Doctoral thesis, 2018. https://repositorium.ub.uni-osnabrueck.de/handle/urn:nbn:de:gbv:700-2018070342.
Pełny tekst źródłaSmith, Allyson Shaidnagle. "NITROGEN AND PHOSPHORUS CYCLING IN MIDWESTERN AGRICULTURAL WETLANDS IN RESPONSE TO ALTERED HYDROLOGIC REGIMES". Thesis, 2011. http://hdl.handle.net/1805/2513.
Pełny tekst źródłaThe transfer of nutrients from US Midwest croplands into surface waters causes eutrophication and a decline in water quality. Temporary retention of nutrient-rich runoff in constructed wetlands can help mitigate these negative impacts through physical entrapment and biological transformation of nitrogen (N) and phosphorus (P). However, with the expectation that wet-dry periods will be more frequent in the region, there is a need to better understand the mechanisms that control nutrient retention and release in US Midwest wetlands constructed on former croplands. In this study, soil cores (30 cm long, 20 cm diam) were collected from two constructed wetlands (4 and 8-yr old), and the surface (0-20 cm) and subsurface (40-60 cm) layers of a cropland where a constructed wetland will be constructed in the future. Soil cores were subjected to either a moist or a dry treatment for 5 weeks, and then flooded with stream water (water depth 6 cm). The flux of nutrients, N2O, cations, and variation in floodwater chemistry (pH and ORP) were monitored for another 5 week period. Porewater was tested during the final 3 weeks of the experiment. Nitrate (0.1-130 mg N m-2 d-1) and inorganic P (Pi) fluxes (0.09-2.9 mg P m-2 d-1) were significantly higher in the dry treatment cores. Regardless of site, the dry treatment also resulted in higher floodwater NO3- concentrations suggesting organic matter mineralization and mineral N build up during the drying phase. However, this initial NO3- release was rapidly denitrified as indicated by the sharp increase in N2O production during that period. In contrast to N, the release of Pi was significantly higher in cores from the cropland. Soil at these sites had higher water extractable Pi and total P. Contrary to the study hypothesis and the results of previous studies, Pi concentration in floodwater and porewater was not correlated with dissolved Fe suggesting that reductive dissolution was not the dominant process controlling P release in US Midwest mineral soils developed from calcareous glacial till. Rather, variation in Ca2+ concentration and its relationship with Pi suggest that dissolution of Ca-containing minerals may be more important and should be the focus of future studies examining the geochemistry of P in these constructed wetlands.
Sikhakhane, Sindisiwe S. "Cost-benefit analysis of the environmental impacts of Darvill Wastewater Works, Pietermaritzburg, KwaZulu-Natal". Thesis, 2002. http://hdl.handle.net/10413/4906.
Pełny tekst źródłaThesis (M.Sc.)-University of Natal, Pietermaritzburg, 2002.
Gebremedhin, Samuel Kahsai. "Analysis and prediction of chemical treatment cost of potable water in the Upper and Middle Vaal water management areas". Thesis, 2009. http://hdl.handle.net/10413/667.
Pełny tekst źródła