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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.
491

Urban stormwater ponds: Evaluation of heavy metals and organic pollutants in stormwater and stormwater sediments

Karlsson, Felix January 2021 (has links)
Urban runoff is generated by precipitation of rain and snowmelt on impervious surfaces.  The increasing demand of urbanization causes contaminants to accumulate on roads,  roofs and pathways. In turn, as runoff wash off these surfaces, contaminants such as heavy metals, particles and organic pollutants end up in the stormwater. Urban stormwater ponds improve water quality of runoff by facilitating contaminants in form of particles. To preserve the function of a stormwater pond accumulated sediment must periodically be removed.Therefore, upland disposal alternatives should be evaluated. This study examined stormwater sediment and outlet stormwater quality in seven and four ponds respectively in the vicinity of Halmstad. 7 heavy metals and 24 organic contaminants were analysed in both sediments and stormwater. Results showed metal and organic contaminant concentrations in stormwater pond discharge and sediment exceeding concentrations reported in guideline values. From the analysed heavy metals, Zn and Pb was considered the most critical contaminants. Heavier organic compounds were more frequently quantified than lighter ones, where 42 % of the analysed organic contaminants were quantified in at least one sample. Variability between inlets and outlets, between ponds and between sampling occasions was observed. The observed variability suggests that the contamination level is influenced by catchment area characteristics and activities. Significant correlation from Spearman’s rank correlation was found between the individual heavy metals (Cu, Cr, Ni, Pb and Zn), which suggest they originate from similar sources
492

Optimalizace peletového kotle pro spalování agropelet / Optimization of Agro-Pellets Boiler

Kurečková, Andrea January 2019 (has links)
The diploma thesis deals with optimization of pellet boiler for agropellets combustion. On the Czech market are mostly available boilers for burning wood pellets. Specially adapted agropellet boilers are pretty expensive. The work is divided into two main parts. The first part contains a research of agropellets, agropellets production and combustions of agropellets. The second part is experimental and describes the combustion test. It describes the measurement procedure, the necessary calculations and evaluation.
493

Statistická analýza znečištění ovzduší vybranými polutanty / Statistical Analysis of Air Pollution by Selected Pollutants

Pernicová, Veronika January 2021 (has links)
This thesis analyses an occurrence of detected pollutant concentrations of nitrogen oxides, dust particles of the size od 10 and 2,5 m and ground ozone in years 2015-2019 in seven chosen locations in Brno agglomeration. In the introduction, the thesis describes basic terms, the issues of air pollution and relevant legislation. Individual pollutants are defined and also their effect on environment and human health. After that, the locations of Brno, for which the analysis is made, is specified. The dynamics of development of individual pollutants is shown through a statistical analysis of individual time lines. The analysis also focuses on the difference in the level of pollution during weekdays, holidays, seasons or rush hour. The quantities are also viewed from the point of view of the relevant air pollution limits and the influence of climatic factors, which significantly affect their concentrations.
494

Dynamique de polluants émergents (parabènes, triclosan et triclocarban) dans le continuum eaux grises - milieu récepteur. / Dynamics of emerging pollutants (paraben, triclosan, triclocarban) in the continuum greywater - surface water.

Zedek, Sifax 12 December 2016 (has links)
Cette thèse, intégrée dans le projet Cosmet’eau et la phase 4 du programme OPUR, apporte de nouveaux éclairages sur la dynamique des parabènes, du triclosan et du triclocarban en milieu urbain sous forte pression anthropique. Ces molécules sont des biocides couramment utilisés en tant que conservateur dans de très nombreux produits de consommation courante comme les cosmétiques, les produits alimentaires ou pharmaceutiques, les textiles, les produits d’entretien. En dépit de leur toxicité, ces molécules ne font l’objet d’aucun suivi réglementaire dans l’environnement. Aussi, ce travail porte sur la dynamique de ces micropolluants en milieu urbain : de leurs sources (à savoir les eaux grises et eaux vannes) jusqu’au milieu récepteur (amont-aval de l’agglomération parisienne par échantillonnage ponctuel et passif) en intégrant leur comportement en station d’épuration à l’échelle de l’ouvrage.Au niveau des sources, cinq types d’eau grise issus de douche, lavabo, lave-linge, lave-vaisselle et vaisselle manuelle ont été considérés. Une variabilité importante des concentrations au sein de chacune des eaux grises et entre les différents types d’eau grise a été observée. Cette variabilité est le reflet des pratiques de consommation des différents volontaires. Au final, les eaux des lave-linge et douche sont les plus contaminées. Pour les parabènes, le linge est la source majoritaire de contamination des eaux de lave-linge, dans le cas des eaux de douche, les personnes et les produits de soins corporels sont les principales sources de contamination.Depuis 2010, les flux quotidiens par habitant de ces molécules ont diminué significativement (d’un facteur compris entre 2 et 7 suivant la molécule). Cette diminution s’explique par (i) les changements de formulation des produits cosmétiques et (ii) l’apparition de nouvelles réglementations plus contraignantes.Le suivi du devenir en station d’épuration (sur Seine Centre), à l’échelle de l’ouvrage, a montré que le traitement primaire (décantation physico-chimique lamellaire) permet un abattement quasi-total du triclosan, les parabènes sont majoritairement éliminés lors de la biofiltration notamment au niveau du premier étage (Biofor). La généralisation d’un traitement tertiaire (du type Carboplus® suivi lors de ce travail) permettrait de réduire ces rejets.Les rejets urbains par temps de pluie (ici les déversoirs d’orage) constituent une source importante de contamination pour le milieu récepteur au regard des niveaux que nous avons observé. La combinaison des rejets des stations d’épuration, par temps sec et par temps de pluie, et des déversoirs d’orage contribue à augmenter les niveaux en parabènes, triclosan et triclocarban de la Seine comme le suivi de deux stations de mesure en amont et aval de l’agglomération parisienne l’a mis en évidence. Les échantillonneurs passifs sont des outils prometteurs pour déterminer la fraction biodisponible du TCS et du TCC. En effet, la méthode développée dans le cadre du projet Cosmet’eau a été appliquée avec succès à la Seine. / This Phd thesis is part of both the Cosmet’Eau project and the OPUR programme. It provides new insights into the dynamics of parabens, triclosan and triclocarban in urban areas under strong human pressure. These molecules are biocides commonly used as preservatives in a wide range of consumer products, such as cosmetics, food and pharmaceutical products, textiles and cleaning products. Despite their toxicity, these molecules are not subject to any regulatory monitoring in the environment. Also, this work deals with the dynamics of these micropollutants in urban areas: from their sources (namely gray water and sewage) to the receiving environment (upstream-downstream of the Parisian conurbation with punctual and passive sampling) along with their behavior at different stages of a wastewater treatment plant.At the source level, five types of greywater from shower, washbasin, washing machine, dishwasher and manual dish washing were considered. Significant variability in concentrations within each greywater and between different types of greywater was observed. This variability reflects the consumption practices of the different volunteers. Besides, the waters from washing machines and showers are the most contaminated. For parabens, clothes are the main source of contamination of washing machine waters, while in shower waters, people and personal care products are the main sources of contamination.Since 2010, per capita daily flows of these molecules have decreased significantly (by a factor between 2 and 7 depending on the molecule). This decrease can be explained by (i) changes in the formulation of cosmetic products and (ii) the emergence of new, more restrictive regulations. The monitoring of the fate in wastewater treatment plant (Seine Centre), at the scale of the device, showed that primary treatment (lamellar physico-chemical decantation) allows a quasi-total removal of triclosan, while parabens are predominantly eliminated during the biofiltration, at the level of the first stage (Biofor). The general use of a tertiary treatment (like Carboplus®, studied during this work) would reduce discharges to receiving waters of parabens, triclosan and triclocarban.Urban discharges during wet weather period (here combined sewer overfows) constitute a major source of contamination for the receiving waters with respect to the measured levels. The combination of sewage treatment plant discharges, during dry and wet weather periods, and combined sewer overfows contributes to increasing levels of parabens, triclosan and triclocarban in the Seine River, as the monitoring of two sites, upstream and downstream of the Paris conurbation, has highlighted it. Passive samplers are promising tools for determining the bioavailable fraction of TCS and TCC. Indeed, the method developed within the framework of the Cosmet'eau project has been successfully applied to the Seine
495

Luftschadstoff- und Treibhausgasemissionen in Sachsen: Verursacher und Trends (Stand Juni 2012)

Schreiber, Ute 18 July 2012 (has links)
Dargestellt werden die Verursacher von Luftschadstoffen und Treibhausgasen, u. a. Groß- und Kleinfeuerungsanlagen, Verkehr und Landwirtschaft sowie der prozentuale Anteil ihrer Emissionen. Dazu gehören beispielsweise Kohlendioxid, Methan, Lachgas und die Luftschadstoffe Kohlenmonoxid, Schwefel- und Stickoxide, leicht flüchtige Stoffe, Staub und Feinstaub, Ammoniak, persistente organische Stoffe und Schwermetalle. Nach den deutlichen Verbesserungen der Luftqualität in den 1990er-Jahren haben sich die Emissionen von Luftschadstoffen und Treibhausgasen in den letzten 10 Jahren auf einem stabilen Niveau eingependelt. Mit Ausnahme von Kohlendioxid und Schwefeldioxid liegt Sachsen bei den Luftschadstoffen unter dem Bundesdurchschnitt.
496

Die Verteilung von Schadstoff durch rotierende Aufwinde in der konvektiven atmosphärischen Grenzschicht unter verschiedenen Turbulenzannahmen

Cieszelski, Rolf 25 October 2016 (has links)
Der Einfluß der Turbulenzstruktur rotierender Aufwinde auf die räumliche Schadstoff verteilung in der konvektiven atmosphärischen Grenzschicht über Land wurde untersucht. Für die Simulation der Aufwinde wurde ein dreidimensionales nicht-hydrostatisches Gitterpunktsmodell verwendet. Die Simulationsergebnisse, die mit verschiedenen Turbulenzparametrisierungen erzielt wurden, zeigen, daß organisierte subskalige Turbulenz zu Änderungen der skaligen Schadstoffverteilungen führen kann. Die Energie- und Helizitätsflüsse zwischen skaligem und subskaligem Regime bei der jeweiligen Turbulenzparametrisierung werden verglichen und die Konsequenzen für die Naßphasenchemie werden diskutiert. / The influence of the turbulence structure of rotating thermals on the spatial pollutant distributions in the convective boundary layer over land was examined. For the simulation of thermals, a threedimensional non-hydrostatic grid point model was used. Simulation results found with different turbulence parametrisations indicate that organized subgrid scale turbulence may lead to alterations of the resolved pollutant distributions. Energy and helicity fluxes between the resolved and subgridscale regime of each turbulence parametrization are compared and the consequences on wet phase chemistry are discussed.
497

Erfassung des atmosphärischen Trübungszustands und seiner zeitlichen Veränderung infolge von Emissionsabnahmen auf Grund sich vollziehender Strukturveränderungen in Mitteldeutschland

Hoyningen-Huene, Wolfgang von, Stettler, M. 27 October 2016 (has links)
In the SANA project (Scientific Attandance Program for the Rehabilitation of the Atmospheric Environment in the German New Federal Lands) different kinds of turbidity measurements are used to characterize the change of the turbidity state of the atmospheric boundary layer produced by atmospheric aerosols within the time span between 1990 and 1995. For this characterization the following turbidity measurements are used: 1.) continuous measurements of the humidity corrected aerosol extinction coefficient obtained with a He-Ne-Lasertransmission path (length: 810 m, wavelength: 0.633 μm) within the urban boundary layer ofLeipzig, 2.) direct measurements ofthe particilate matter (PM10) concentration, 3.) combined measurements of spectral aerosol optical thickness (within the spectral range of0.35 - 1.1 μm) and sky brightness in the solar almucantar plane for cloud free situations, 4.) integrated radiation flux density measurement (Globalradiation). In all measurements a decrease of the atmospheric aerosol turbidity could be stated in the time span of 1990/91 to 1995: for the extinction coefficient and the particulate matter within the boundary layer of approximately 60 %, the turbidity coefficient derived from the spectral aerosol optical thickness ( corrected for the influence of the stratospheric volcanic aerosol by the Pinatobo) give a reduction of 57 %. The combined measurements of spectral aerosol optical thickness and the sky brightness are used for the determination of the main climate-relevant aerosol parameters: aerosol phase function, asymmetry parameter, columnar aerosol size distribution and apparent columnar refractive index. The largest change in the columnar aerosol size distribution could be stated in the size range of 0.2 - 0.8 μm (radius), also a reduction of approximately 60 %. Together with the measurements of the downwelling flux density an estimation of the aerosol absorption in kind of the imaginary part of the refractive index is made. The imaginary part is reduced in the same way: 1991: k = 0.021, 1994 and 1995 k = 0.008. A first estimation of the anthropogenic shortwave radiative forcing produced by the old East German air pollution of the on the basis of these data gives a change in the shortwave radiative balance of approximately -8 W/m2. / Im Rahmen des SANA Projekts (Wissenschaftliches Begleitprogramm zur Sanierung der Atmosphärenumwelt) wurden verschiedene Trübungsmessungen verwendet, um die Veränderungen im Trübungszustand in der atmosphärischen Grundschicht, hervorgerufen durch Aerosole, im Zeitraum von 1990 bis 1995 charakterisieren zu können. Dazu wurden folgende Trübungsmessungen verwendet: 1.) kontinuierliche Messungen des feuchtekorrigierten Aerosolextinktionskoeffi.zienten mit Hilfe einer Laser- Transmissionsstrecke (Länge 810 m, He-Ne-Laser Wellenlänge: 0.633 μm) in der urbanen Grundschicht von Leipzig, 2.) direkte Messungen der Schwebstaubkonzentration, 3.) kombinierte Messungen von spektraler optischer Dicke des Aerosols (im Spektralbereich von 0.35 - 1.1 μm) und Himmelshelligkeitsfunktion im Almukantar unter wolkenfreien Bedingungen, 4.) integrale Strahlungsflußdichtemessungen (Globalstrahlung). In allen Messungen konnte im Zeitraum 1990/91 bis 1995 eine Abnahme der Aerosoltrübung festgestellt werden: Für den Extinktionskoeffi.zienten und die Schwebstaubkonzentration in der urbanen Grundschicht ungefähr 60 %, für den aus den spektralen optischen Dicken des Aerosols abgeleiteten Trübungskoeffizienten (korrigiert um den Beitrag des stratosphärischen Vulkanaerosols des Pinatubo) 57 %. Die kombinierten Messungen von spektraler optischer Dicke des Aerosols und der Himmelshelligkeitsfunktion dienten der Bestimmung der wesentlichen klimarelevanten Aerosolparameter: Aerosolphasenfunktion, Asymmetrieparameter, columnarer Aerosolgrößenverteilung und columnarer Brechungsindex des Aerosols. Die größte Änderung in der columnaren Aerosolgrößenverteilung ist im Radienbereich 0.2 - 0.8 μm festgestellt worden, ebenfalls eine Reduktion von ungefährt 60 %. Zusammen mit den Messungen der abwärtsgerichteten Strahlungsflußdichte wurde eine Abschätzung der Aerosolabsorption in Form des Imaginärteils des Brechungindex vorgenommen. Der Imaginärteil verringert sich in gleicher Weise: 1991: k = 0. 021, 1994 und 1995: k = 0. 008. Auf der Grundlage dieser Daten konnte der anthropogene Anteils des kurzwelligen Strahlungsforcings, das durch die Luftverunreinigung unter den alten Ostdeutschen Bedingungen hervorgerufen wird, mit ungefähr -8 W/m2 Änderung in der kurzwelligen Strahlungsbilanz abgeschätzt werden.
498

Characterization of Roadway Stormwater System Residuals for Reuse and Disposal Options

Jang, Yong C., Jain, Pradeep, Tolaymat, Thabet, Dubey, Brajesh, Singh, Shrawan, Townsend, Timothy 15 March 2010 (has links)
The chemical characterization of sediments accumulated in catch basins and stormwater ponds provides important information for assessing risks associated with management of these residuals upon removal of accumulated deposits in stormwater systems. In this study, over a period of 15 months, more than 150 residual samples were collected from 77 catch basin units and 22 stormwater ponds from 16 municipalities throughout the state of Florida. Concentrations (mg/kg) of metals and metalloids (arsenic, barium, cadmium, chromium, copper, lead, mercury, nickel, selenium, silver, and zinc) and trace organics (volatile organics, semi-volatile organics, herbicides, and pesticides) in the sediments were measured. In addition, the synthetic precipitation leaching procedure (SPLP) was utilized to evaluate pollutant leachability risk for a subset of the samples collected. Measured pollutant concentrations were compared to corresponding risk-based guidelines in Florida (i.e., Florida soil cleanup target levels) to assess potential human health risks of beneficial use of these residuals through land application. Leached concentrations were compared to risk-based water quality guidelines (i.e., Florida groundwater cleanup target levels) to examine the potential for groundwater contamination. Although several metals (arsenic, barium, chromium, copper, nickel, lead, and zinc) were routinely detected in the catch basin and stormwater pond sediments, their concentrations were generally lower than the Florida's risk-based cleanup target levels for soils. A small number of organochlorine compounds (e.g., 4,4′-DDE, 4,4′-DDT) were detected, but only in a limited number of the samples (less than 10%); leaching of trace organic pollutants above the Florida risk-based groundwater thresholds was rare. The results suggest that when land-applied or beneficially used, these residuals are not expected to pose a significant threat to human health or the environment and the results of this research will provide stormwater managers and environmental management authorities with a useful resource to examine proper disposal and beneficial use of catch basin and stormwater pond sediments.
499

Characterization of Pollutants in Florida Street Sweepings for Management and Reuse

Jang, Yong Chul, Jain, Pradeep, Tolaymat, Thabet, Dubey, Brajesh, Townsend, Timothy 01 November 2009 (has links)
Disposal and beneficial-use options for street sweeping residuals collected as part of routine roadway maintenance activities in Florida, USA, were assessed by characterizing approximately 200 samples collected from 20 municipalities. Total concentrations (mg/kg or μg/kg) and leachable concentrations (mg/L or μg/L) of 11 metals and a number of organic pollutant groups (volatile organics, semi-volatile organics, pesticides, herbicides, carbamates) in the samples were measured. The synthetic precipitation leaching procedure (SPLP) was performed to evaluate the leachability of the pollutants. From the total metal analysis, several metals (e.g., arsenic, barium, chromium, copper, nickel, lead, and zinc) were commonly found above their detection limits. Zinc was found to have the highest mean concentration of all metals measured (46.7 mg/kg), followed by copper (10.7 mg/kg) and barium (10.5 mg/kg). The metal with the smallest mean concentration was arsenic (0.48 mg/kg). A small fraction of the total arsenic, barium, lead, and zinc leached in some samples using the SPLP; leached concentrations were relatively low. A few organic compounds (e.g., 4,4′-DDT, endrin, and endosulfan II) were detected in a limited number of samples. When the total and leaching results were compared to risk-based Florida soil cleanup target levels and groundwater cleanup target levels, the street sweepings were not found to pose a significant human-health risk via direct exposure or groundwater contamination.
500

Legacy persistent organic pollutants and chemicals of emerging concern in Sweden : from indoor environments to remote areas

Newton, Seth January 2013 (has links)
Bulk atmospheric deposition samples were taken every two months for a year in 2009-2010 at two sites in northern Sweden and analyzed for a suite of legacy and emerging persistent organic chemicals including legacy organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs)  and novel flame retardants (NFRs).  To further investigate the urban occurrence and contribution to remote contamination of flame retardants, indoor air, ventilation system air, and dust were sampled in several microenvironments in Stockholm during the winter of 2012 for analysis of PBDEs, isomer-specific hexabromocyclododecane (HBCDD), and NFRs.  Outdoor air and soil samples were also sampled around the same time period for analysis of the same compounds.  Five emerging pollutants were detected in atmospheric deposition: the current-use pesticides trifluralin and chlorothalonil; and the NFRs 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH), 1,2-bis(tribromophenoxy)ethane (BTBPE), and Dechlorane Plus (DP).  A decrease in the fraction of the anti isomer of DP was observed at the more remote site, indicating isomer-selective degradation or isomerization during long range atmospheric transport.  The more remote site also received more total deposition of organic pollutants despite its receiving less precipitation.  Although PBDEs and emerging organic pollutants were detected, the bulk of the deposition consisted of PCBs and hexachlorocyclohexanes (HCHs) at both sites.   Several NFRs were identified in indoor and ventilation air samples including TBECH, pentabromotoluene (PBT), hexabromobenzene (HBB), 1,2-bis(pentabromodiphenyl)ethane (DBDPE), 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (EHTBB), and bis(2-ethylhexyl)-3,4,5,6-tetrabromo-phthalate (TBPH).  There was no significant difference between concentrations of contaminants in ventilation system air and indoor air indicating that the flame retardants included in this study reach the outdoor environment via ventilation systems.  Dust and outdoor air samples have only been analyzed for HBCDDs so far.  HBCDD concentrations in apartments, offices, and schools were lower than reported concentrations for other countries in similar microenvironments.   However, an enrichment of α-HBCDD compared to γ-HBCDD was observed in dust taken from near treated products in stores when compared to dust taken directly from those products.  Very low concentrations of HBCDDs were detected in outdoor air.

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