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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.
291

Μελέτη των ατμοσφαιρικών ρύπων στην πόλη της Πάτρας με τη μέθοδο της ανάλυσης σε κύριες συνιστώσες

Σούφλα, Ευαγγελία 04 September 2013 (has links)
Μελέτη των ατμοσφαιρικών ρύπων στην πόλη της Πάτρας για το έτος 2010 με τη μέθοδο της ανάλυσης σε κύριες συνιστώσες και κάνοντας χρήση του στατιστικού πακέτου Minitab16 / Research on air pollutants in the city of Patras for the year 2010 using the method of Principal Components Analysis. The results are elaborated using the statistical program minitab16.
292

Statistical modelling of daily mortality and air pollutant concentrations

馬時樂, Ma, Sze-lok, Stefan. January 2003 (has links)
published_or_final_version / Community Medicine / Doctoral / Doctor of Philosophy
293

Determination of organic pollutants in air and soil by supercritical fluid extraction, capillary electrophoresis, chromatographic andelectrochemical methods

龍銀花, Long, Yinhua. January 2001 (has links)
published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy
294

ROLE OF ARYL HYDROCARBON RECEPTOR IN CHRONIC INFLAMMATORY DISEASES

Arsenescu, Violeta 01 January 2009 (has links)
Aryl Hydrocarbon Receptor (AhR) is a ligand-actviated receptor known as the dioxin receptor. Environmental pollutants called dioxin-like toxicants are found in food, cigarette smoke, automobile exhaust and air. Therefore, they could chronically amplify the pathology of numerous chronic inflammatory diseases. AhR is a well known target of these environmental chemicals that disrupt endocrine signaling. By the year 2020, the number of people older than 60 years is expected to top 1 billion. The burden of treating chronic disease is significant both in dollars spent and in lost productivity. The need to identify risk factors for chronic diseases must be evaluated along with diet and lifestyle factors that will promote healthy aging. The studies presented in this dissertation tested the hypothesis that habitual exposure to dioxin-like contaminants contributes to chronic inflammatory disease states through activation of AhR pathway. Due to their lipophilicity, dioxin like toxicants (like PCB 77) accumulated in mice' visceral adipose tissue and induced adipocytes maturation and ectopic fat deposition. Exposure to persistent organic pollutants, such as polychlorinated biphenyls (PCB 77) can cause endothelial cells activation and inflammation by inducing pro-inflammatory signaling pathways. In our studies, PCB 77 had cumulative effects in Angiotensin II - induced Abdominal Aortic Aneurysm (AAA) by exacerbating inflammation in and around the aortic wall. More, PCB 77 increased mortality in mice that developed AAA. In order to appreciate the AhR involvement in inflammation we used a mouse model of Inflammatory Bowel Disease(IBD). Mice that had a reduced Ahr Receptor expression developed a less severe colitis and had a decreased general inflammatory status. These data provide evidence that exposure to environmental toxicants could augment inflammation and contribute to the social burden of obesity and obesity related chronic inflammatory diseases.
295

Föroreningsspridning via ledningsgravar : en fältstudie på Köpmanholmens industriområde

Gardfors, Lars January 2005 (has links)
<p>Sewer trenches usually contain material with a higher hydraulic conductivity then the adjacent soil. Thus they can serve as paths of preferential flow in a polluted area. Wastewater from factories can also leak from wastewater pipes and pollute the soil in the sewer trenches.</p><p>The purpose of this project was to investigate pollutions in sewer trenches and in sewer pipes in the industrial area of Köpmanholmen, 20 km south of Örnsköldsvik in the north of Sweden. To make an estimation concerning the potential of transport of pollutions in sewer trenches, hydrological calculations were performed.</p><p>Leakage to any greater extent did not seem to be a problem in the area. This is the case both for the concrete and the wooden pipes that have served as factory wastewater pipes. A large transport in the lengthwise direction of the sewer trenches was not shown to exist. Instead the greatest risk of transport from a polluted area seems to come from infiltration into wastewater pipes, where the pollutants can flow readily to the recipient or wastewater treatment plant.</p> / <p>Rörgravar innehåller ofta grövre material med högre hydraulisk konduktivitet än omgivande jord och kan därför tjäna som spridningsvägar från förorenade områden. Avloppsvatten från fabriksområden kan också misstänkas ge upphov till föroreningar i rörgravar via läckage från avloppsrören.</p><p>Detta arbete har haft som mål att utreda föroreningssituationen i ledningsgravar och avloppsledningar på Köpmanholmens industriområde, ca 2 mil söder om Örnsköldsvik. För att bedöma ledningsgravarnas potential att sprida föroreningar har också hydrologiska beräkningar har gjorts.</p><p>Läckage i någon större omfattning från avloppsledningar har inte kunnat påvisas. Detta gäller både betongledningar och den trätub som har utgjort fabriksavlopp på området. Inte heller har någon föroreningsspridning kunnat påvisas i ledningsgravarnas längdriktning. Den största risken för spridning av föroreningar verkar istället vara via infiltration till avloppsledningarna. Detta ger en snabb transport från förorenade områden till recipient eller reningsverk.</p>
296

Oro taršos nustatymas naudojant hy split oro pernašos modelį ir izotopų santykio metodą / Determination of air pollution using Hysplit air transmission model and stable isotopes mass ratio method

Kaluškevičius, Gytis 22 January 2014 (has links)
Šiame darbe apžvelgiamos aerozolio dalelių savybės, jų sudėtis, tyrimo metodai ir poveikis klimatui. Nagrinėjamos jų matavimo technikos ir galimas poveikis klimatui, dėl kurio ir oro taršos kyla uždavinys tyrinėti aerozolio daleles Lietuvoje. Kadangi oro teršalai gali būti atnešti iš kitų valstybių, tai norint rūpintis aplinkos apsauga, reikia nustatyti jų kilmę, ištirti oro masių judėjimą. Atomo izotopų santykio matavimas gali padėti aptikti teršalus, o oro masių judėjimo modeliavimas naudojant hy split metodą - išsiaiškinti, iš kur jie kilę. Šiame darbe tam buvo panaudoti oro masių siurbimo, vykdyto Vilniuje, Fizikos institute, duomenys. Rezultatai rodo, kad dažniausiai oro masės į Lietuvą ateina nuo Atlanto vandenyno, taip pat nuo Rusijos ir Skandinavijos. Iš ten gali ateiti ir teršalai. / It is reviewing properties, research methods, composition, affects on climate of aerosols in this work. It analyses measurement techniques, affects on climate, because from it and air pollution it is useful to research particles of aerosols in Lithuania. Air pollutants can be transported from other countries, so we need to find out origin of aerosols and transmission of air masses to take care of environment. Measurement of atom isotopes ratio can help to find pollutants, and mases transmission modeling using hy split method - to find out origins. In this work air mass pumping in Vilnius, Institute of Physics, data was used for that purpose. Results shows that most frequently air masses comes to Lithuania from Atlantic ocean, and Russia and Scandinavia too. The pollutants can come from that locations.
297

A survey of organic pollutants in the South African sewage sludges.

Mamabolo, Mabu Matsatsi. January 2006 (has links)
A comprehensive literature survey looking at different aspects of organic contaminants in sewage sludge is incorporated in the thesis. It is clear from the data available that plants do not take up most of the organic pollutants. However, a risk of contamination of the food chain exists when sludge is spread directly onto crops that are to be consumed raw or semi-cooked. The major source of human exposure to sludge-borne organic pollutants is through the consumption of animal products such as meat and milk through the bioaccumulation of compounds such as polychlorinated dibenzo-p-dioxins and -furans (PCDD/Fs), polychlorinated biphenyls (PCBs) or polynuclear aromatic hydrocarbons (PAHs). This is due to the ingestion of soil and sludge by livestock due to the spreading of sludge on the land used for grazing. Currently little is known about the plant uptake of phthalates and nonylphenols, which are present in relatively high levels in sludge. Included in the literature survey is a list of the most common methods normally used for extraction of organic compounds and the possible methods of analysis. What is noted is that there is no universally accepted and validated analytical method for analysing most of the organic compounds. In addition, data concerning levels of organic pollutants is scarce worldwide. The methods selected for this project were EPA Methods 35IOC (Liquid-liquid extraction) and 3540C (Soxhlet extraction) for the aqueous and solid sewage sludge respectively. These two methods were chosen because they are simple, inexpensive and effective. The chosen purification method was the sulfur clean-up process (EPA Method 3660B). This is because sulfur precipitates were observed in most of the concentrated extracts, especially from the solid samples. A total of 109 samples from 78 sewage works were extracted, using Soxhlet extraction for solids and liquid-liquid extraction for liquid samples. All the extracts were analysed using GC-MS. The identification of the organic compounds was made possible by the use of GC-MS Wiley library. A total of 712 organic compounds were identified in the South African sewage sludge. These included Phenols, Pesticides, PAHs, Phthalates, PCBs, Furans, Amines, Aldehydes, Esters, Acids, Chlorinated Hydrocarbons, Alcohols, Hydrocarbons and Others (all sorts of organic compounds that did not belong to the named categories). The extraction efficiency and reproducibility using a "clean" sludge matrix was carried out. The results showed that the method chosen for extraction i.e. Soxhlet method had an efficiency of over 80% and the results were reproducible. A total of 14 samples were selected for the quantification of p-cresol, nonylphenol and pesticides listed in the current legislation. The results showed negative results for pesticides, confirming that the pesticides listed in the legislation are not the compounds that need to be regulated as far as organic pollutants are concerned. The reasons for this are most likely due to the fact that most of the pesticides listed are banned or their use is severely restricted. The results for the quantification of p-cresol and nonylphenol, when comparing the liquid and the solid extracts of the liquid sludge, show that 99% of p-cresol is concentrated in the liquid phase. The opposite is true when looking at nonylphenol where 90% of it is trapped in the solid matrix leaving 10% in the liquid phase. It is also noted that liquid sludge contains high concentrations of both p-cresol and nonylphenol when compared to the solid sludge. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2006.
298

Determination of the inorganic pollutants in South African sewage sludges.

Tesfai, Fitsum Kidane. January 2004 (has links)
A total of 78 sludge samples originating from 69 sewage works of South Africa were used in this investigation. Seven of the sludge samples were liquid and the rest were solid. Moisture content, pH and mineral ion determination using ICP-OES were carried out. The methods used to digest the samples were EPA 3050B and 301OA for solid sludge and effluent (liquid sludge) respectively. The moisture content determination showed that fresh wet sludge was composed of water between 40 to 90 %. The minimum moisture content was found to be 2.70 % while the maximum was 88.50 % with a mean value of41 %. The pH results showed that the majority sludges produced had pH values between 4.8 - 6.5. The ICP-OES results which involved analysis and quantification of 22 mineral ions showed that the order ofabundance that was most common to the majority ofthe samples was P, Ca, Fe, AI, Mg, K, Zn, Na, Si, Mn, Cu, Cr, Ba, Pb, Sr, Se, B, Ni, Co, Mo and Cd. Even though phosphorus was the most abundant, 11 of the samples had calcium as the highest element. Looking at the heavy metals, zinc was the highest with cadmium being the least. The order of abundance in majority of the solid samples (64 in total) was Zn> Pb > Ni> Cd with the relative metal concentrations of Cu, Se, B, Cr, Co & Mo varying among the sewage works. The liquid samples also had phosphorus as one of the most abundant elements but was 102 times smaller comparing to solid sludges. In addition, most of the transition elements were found to be below the detection limit. Beryllium was exceptionally found to be below detection limit in all sludge samples. The results have pointed out that industrial effluent have 3 times the level of pollutants when compared to the domestic effluents. However, the methods of preparing sludge have no influence on the content or quantity of mineral ions. The results have been compared with 1989 data. The outcome shows that concentrations of the major nutrients namely calcium, magnesium and potassium remained relatively constant whereas phosphorus increased by more than 3 fold. On heavy metals, the data shows that the mean concentration level of Zn, Cu, Cr, Pb, Ni and Cd declined whereas that of Se, B and Mo showed an increase in 2002, all to a varying degree. The current results were also compared with the current maximum limits as stipulated in the permissible utilization and disposal of sewage sludge government guideline. The amount of Cu, Se, Pb and Zn were found to be above the limit in more than 90 % of the samples. There was no sewage works that met the required limits for all the elements of interest. When these results are compared with the intenational limits, all the elements fall within the acceptable range. It is therefore clear that the current South African guideline limit is too restrictive. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2004.
299

Acquisition de tolérance et modification de structure des communautés périphytiques : une réponse précoce à la pression urbaine dans les milieux aquatiques / Tolerance acquisition and structure modification of periphytic communities : an early-warning response to urban contamination of aquatic ecosystems

Fechner, Lise 14 December 2010 (has links)
La contamination des milieux aquatiques urbains se caractérise aujourd'hui par un mélange de micropolluants d'origines et de types variés. Les conséquences de ce type de contamination, multiples mais faibles et chroniques, sur les écosystèmes aquatiques sont difficiles à évaluer. En effet, il est difficile d'une part de dresser un état des lieux précis de la contamination et d'autre part, de relier cette contamination à la réponse biologique des organismes exposés puisqu'elle n'engendre pas nécessairement des effets visibles et immédiats. Cette étude a pour objectif de développer une méthodologie permettant d'utiliser le périphyton pour évaluer l'impact d'une contamination urbaine typique. Les biofilms sont des communautés aquatiques complexes jouant un rôle primordial dans le fonctionnement des écosystèmes aquatiques. Leur réponse biologique à une perturbation peut s'évaluer au niveau structurel comme au niveau fonctionnel. Une première étape de ce travail a consisté à développer d'une part un test de toxicité aiguë permettant d'évaluer la tolérance de la composante hétérotrophe des biofilms selon le concept PICT, et d'autre part l'utilisation de la technique d'empreinte génétique ARISA pour évaluer des modifications de structure des communautés bactériennes et eucaryotes des biofilms. Les méthodologies développées ont ensuite été testées au laboratoire par des expositions de périphyton à des métaux à des concentrations environnementales. Par la suite, elles ont pu être déployées in situ : d'abord dans un gradient de contamination multi-métallique sur la Seine avec des prélèvements ponctuels de biofilms naturels ainsi qu'une expérience de transposition (amont/aval de l'agglomération parisienne). Enfin, le lien entre la tolérance du périphyton et la contamination métallique globale du milieu a été exploré à l'échelle d'un bassin versant. Les résultats sont prometteurs quant à l'utilisation du périphyton pour évaluer l'impact d'une contamination urbaine / Urban aquatic ecosystems are these days contaminated by mixtures of micropollutants of diverse types and origins. Such contaminations, which are multiple, chronic and non-lethal, raise increasing concern among the scientific community. Indeed, a precise evaluation of exposure levels is difficult to obtain. Moreover, establishing a causal link between contamination and the induced biological response of aquatic organisms is complex as no direct and visible effects can be observed. The aim of this study is to develop a methodology for the use of periphyton as a biomarker of urban pollution. Biofilms are complex aquatic communities and play an important role in aquatic ecosystems. Their response to a disruption can be assessed both in terms of structure or functional modifications. Our first step was to develop both a PICT approach with a new short-term toxicity test to measure the tolerance to metal of the heterotrophic component of biofilms and the use of a fingerprinting technique (ARISA) to reveal structure modifications of both bacterial and eukaryotic communities. The methodologies thus developed were tested in a microcosm study by exposing periphyton to metals at environmental levels. They were then used in field studies: first in a multi-metallic gradient along the Seine river by punctual sampling of natural periphyton and also in a translocation study (upstream/downstream the Paris urban area). Furthermore, the link between biofilm tolerance levels and the global metallic contamination was explored at the watershed scale. It is hoped that the future use of this approach will help to understand the impacts of human activities, especially toxic pressure, on aquatic ecosystems
300

Mixed fuels composed of household waste and waste wood : Characterization, combustion behaviour and potential emissions

Edo Giménez, Mar January 2016 (has links)
Incineration with energy recovery is the main disposal strategy for waste that cannot be reused or recycled, and a well-established source of energy in Europe, especially in Sweden where 2.2 Mtonnes of waste including domestic and imported municipal solid waste (MSW) and waste wood (WW) were combusted during 2015. However, owing to its inherent heterogeneous composition, inclusion of such waste in Waste-to-energy (WtE) technologies is challenging. These heterogeneities may lead to operationally-related issues in the WtE facilities and contribute to toxic emissions, which can be reduced by waste pre-treatment technologies.    This thesis examines the variations in the composition of MSW and WW streams used as a fuel supply in WtE facilities after undergoing waste pre-treatment technologies, and the effect of fuel composition on its combustion behaviour and formation of persistent organic pollutants (POPs) such as polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). The overall objective is to contribute to a more thorough understanding of the selection of waste pre-treatment technologies to mitigate harmful emissions into the atmosphere when waste fuels are combusted in WtE facilities.    This thesis describes the high variability of contaminants in domestic and imported WW and suggests adaptation of WW pre-treatment techniques to produce fuels with a low potential for generating pollutants. A comparison of mechanical solid waste pre-treatments revealed that screening and shredding is more efficient than extrusion for reducing emissions of pollutants such as PCDDs and PCDFs in combustion. The evaluation of the combustion behaviour of MSW-based fuels showed a three-stage oxidative decomposition, and an acceleration of the decomposition of the MSW compared to the lignocellulosic materials, which may be attributed to the presence of food waste and plastics in the MSW. Combustion tests of fuel blends containing WW and MSW-based fuels with different food waste content suggested that WW, not food waste content, is the key factor for the formation of PCDDs, PCDFs, and polychlorinated biphenyls (PCB), benzenes (PCBzs) and phenols (PCPhs). Torrefaction may be a suitable technology for improving the properties of waste as a fuel e.g. due to its low PCDD and PCDF emissions. / Förbränning med energiåtervinning är det huvudsakliga sättet att ta hand om avfall som inte kan återanvändas eller återvinnas. Det är en väletablerad energikälla i Europa och särskilt i Sverige där 2,2 miljoner ton avfall, däribland inhemskt och importerat hushållsavfall och returträ, förbrändes under 2015. På grund av den heterogena sammansättningen hos hushållsavfall och returträ är förbränning av dessa material i anläggningar med energiåtervinning (så kallade WtE-anläggningar) förknippade med en del driftsrelaterade utmaningar. Det kan även ge upphov till miljöfarliga utsläpp, som dock kan reduceras genom förbehandling av avfallet. I denna avhandling har variationer i sammansättningen hos hushållsavfall och returträ som förbränns i WtE-anläggningar undersökts. Effekten av bränslemixens sammansättning och ev förbehandling på bränslets förbränningsegenskaper samt bildning av långlivade organiska föroreningar (så kallade POPar) såsom polyklorerade dibenso-p-dioxiner och polyklorerade dibensofuraner vid förbränning har utvärderats. Det övergripande målet är att bidra till en djupare förståelse av hur valet av förbehandlingsteknik för avfall kan bidra till att minska skadliga utsläpp till luft när avfallsbränslen förbränns i WtE-anläggningar. Denna avhandling beskriver den stora variabiliteten av metall- och materialföroreningar i inhemskt och importerat returträ och föreslår förbehandlingstekniker för att producera bränslen med låg potential att generera föroreningar. En jämförelse av mekaniska förbehandlingstekniker visade att mekanisk sönderdelning och separering (krossning och siktning) är mer effektivt än s.k. högtrycks-pressning för att minska utsläppen av föroreningar som dioxiner och furaner vid förbränning. Utvärderingen av bränslemixar innehållande hushållsavfall uppvisade en oxidativ nedbrytning i tre steg vid förbränning, och en accelererad nedbrytning av avfallsmaterialet jämfört med vedmaterialet i bränslet, troligen som effekt av innehållet av matavfall och plast i hushållsavfallet. Förbränningsförsök med bränsleblandningar av returträ och hushållsavfall med olika innehåll av matavfall visade att mängden returträ, och inte mängden matavfall, är den viktigaste faktorn för bildning av dioxiner, furaner, klorbifenyler, klorbensener, och klorfenoler. Torrefiering kan vara en lämplig teknik för att förbättra avfallets bränsleegenskaper, t.ex. på grund av dess låga emissioner.

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