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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.
1

Application of Passive Samplers for SARS-CoV-2 Wastewater Surveillance

Fang, Wanting 31 July 2023 (has links)
SARS-CoV-2 wastewater surveillance is a promising tool for monitoring the spread of infection during pandemic outbreaks. 24-hour composite sampling of wastewater using autosamplers is the preferred means for wastewater surveillance sample collection. Autosamplers however require a significant capital cost and furthermore some sampling locations are not amenable to autosampler deployment because of a lack of space and lack of access to electricity. Grab sampling is an alternative to auto sampling for wastewater surveillance, however it may be less effective compared to 24-hour composite sampling due to the possibility to miss the collection of shed disease targets during critical shedding events. Torpedo-style passive samplers packed with medical gauze and tampon-style passive samplers are alternatives to grab sampling when deployment of autosamplers is not possible. Torpedo-style and tampon-style passive samplers are characterized as being easy to deploy and collect and have shown promise for disease surveillance using wastewater. Although passive samplers have shown the ability to detect SARS-CoV-2, they have not demonstrated the ability to quantify the viral load in the wastewater due to the fact that the collection of the liquid phase of the sampler is not consistent across the deployment period of a passive sampler. As SARS-CoV-2 disease targets have been shown to largely partition to the solids phase of wastewaters, it is hypothesized that mass fraction quantitation may enable passive samplers to quantify wastewater signals comparably to autosamplers. In this study, wastewater samples were collected from the same location over a period of three months from a sewer access point at the University of Ottawa using conventional 24-hour auto sampling. Two types of torpedostyle passive samplers and a tampon-style passive sampler were tested to assess whether passive sampler measurements of SARS-CoV-2 N1 and N2 gene targets can be used in the place of autosampler quantitated values. When comparing the wastewater characteristics of centrifuged pellets collected by various passive samplers and a conventional autosampler, the results of this study showed that the torpedo-style passive sampler packed with two pieces of gauze (P2) collected significantly lower water content compared to the autosampler, and P2 collected significantly greater total solids and volatile solids compared to the autosampler. When measuring SARS-CoV-2 N1 and N2 signals, the results indicate that N1 and N2 gene region copy numbers from all of the samplers were not significantly distinct. However, the P2 sampler, a torpedo-style passive sampler packed with four pieces of gauze (P4), and the tampon-style passive sampler (T) captured a greater quantity of pepper mild iii mottle virus (PMMoV) gene targets compared to the autosampler; where PMMoV is the most commonly measured fecal biomarker for wastewater surveillance of SARS-CoV-2. The greater quantity of PMMoV gene targets compared to the autosampler was likely due to proportionally higher total solids and volatile solids in the centrifuged pellet material captured. When N1 and N2 measurements were normalized against sample volume, pellet mass or PMMoV gene copy numbers, P2, P4, and T showed no significant differences compared to the autosampler. In contrast, differences were observed between passive samplers and the autosampler when PMMoV measurements were normalized against the matrix volumes or pellet mass. High statistical percentage differences were observed between all passive samplers and the autosampler. Overall, passive samplers are reliable, cost-effective devices for sampling disease targets in wastewater if results are expressed as copies/g or copies/copies PMMoV. These devices are feasible substitutes for autosamplers when detection and quantification of SARS-CoV-2 in wastewater are required. P2 passive samplers using units of measurement of copies/g are recommended for SARS-CoV-2 surveillance in the wastewater.
2

Desenvolvimento de amostrador passivo para amônia na atmosfera

Lima, Marco Aurélio Oliveira January 2011 (has links)
100 f. / Submitted by Ana Hilda Fonseca (anahilda@ufba.br) on 2013-04-10T16:12:53Z No. of bitstreams: 1 DISSERTAÇÃO MESTRADO-MARCO AURELIO OLIVEIRA LIMA.pdf: 2334577 bytes, checksum: d3b4b7dd1462c1c2c43d4f128b2c14c1 (MD5) / Approved for entry into archive by Ana Hilda Fonseca(anahilda@ufba.br) on 2013-05-10T16:08:45Z (GMT) No. of bitstreams: 1 DISSERTAÇÃO MESTRADO-MARCO AURELIO OLIVEIRA LIMA.pdf: 2334577 bytes, checksum: d3b4b7dd1462c1c2c43d4f128b2c14c1 (MD5) / Made available in DSpace on 2013-05-10T16:08:45Z (GMT). No. of bitstreams: 1 DISSERTAÇÃO MESTRADO-MARCO AURELIO OLIVEIRA LIMA.pdf: 2334577 bytes, checksum: d3b4b7dd1462c1c2c43d4f128b2c14c1 (MD5) Previous issue date: 2011 / Este estudo teve como principal objetivo desenvolver um amostrador passivo para monitoramento de amônia na atmosfera. A configuração do amostrador passivo (AP) desenvolvido minimiza problemas de turbulência do ar e outras interferências de amostragem: um cilindro de polietileno (21 x 12 mm), fechado no fundo, com uma tela de aço inox (0,08 x 0,125 mm) adaptada na entrada de ar seguida por um filtro de teflon. Após o caminho de difusão (12 mm), encontra-se um filtro (celulose) impregnado com reagente apropriado (C2H2O4, ácido oxálico; C6H8O7, ácido cítrico, solução a 0,3 %) para fixar NH3 gasosa difundida. Após reação com a solução ácida, a concentração de amônia fixada no filtro foi medida por espectrofotometria molecular Visível (λ = 630 nm). O desempenho do amostrador passivo foi avaliado em campo a partir de medidas simultâneas com analisador contínuo para amônia em áreas sob influência industrial próximas ao Pólo Industrial de Camaçari, onde os amostradores passivos foram expostos em estações da Rede de Monitoramento de Ar da Cetrel: Gravatá em Camaçari, Leandrinho em Lamarão do Passé e Concórdia em Dias D´Ávila. Testes para avaliação das soluções absorvedoras utilizando três ácidos (oxálico, cítrico e fosfórico) foram desenvolvidos em diferentes períodos de exposição (1, 3 e 7 dias). As medidas com o AP proposto revelaram exatidão variando entre 2,4 a 13 % usando ácido cítrico como reagente no meio absorvedor, em períodos de exposição até 3 dias, e entre 1,3 a 12% para ácido oxálico com exposição de 7 dias. A precisão das medidas feitas usando conjuntos de 3 a 6 amostradores variou de 6,6 a 16% para o ácido cítrico (tempo de exposição até 3 dias) e de 2,8 a 19% para o ácido oxálico (tempo de exposição de 7 dias). Os limites de detecção para as medidas de NH3 na atmosfera utilizando o AP foram determinados como 0,49 μg m-3 (0,71 ppb) para 1 dia de exposição usando ácido cítrico e 0,071 μg m-3 (0,10 ppb) para 7 dias de exposição usando ácido oxálico, o que mostra sua adequação para medidas em atmosferas com concentração extremamente baixas como a de áreas remotas. A capacidade do amostrador passivo é de 159 e 227 μg de NH3 utilizando-se ácido cítrico e ácido oxálico respectivamente, onde isso mostra que o AP pode ser usado também em ambientes de trabalho onde as concentrações são muitas vezes mais elevadas do que em ambientes externos / Salvador
3

Développement de capteurs passifs pour le diagnostic et la gestion environnementale du cuivre en zone viticole / Development of a new passive sampler for the assessment of copper in vineyard soils

Perez, Magali 07 December 2015 (has links)
L’utilisation répétée de la bouillie bordelaise pour la lutte contre le mildiou a entrainé une accumulation de cuivre dans les sols viticoles. Afin d’évaluer l’impact de cette pollution, les capteurs passifs sont fréquemment utilisés pour renseigner sur la biodisponibilité du cuivre et donc sur sa toxicité. Toutefois, au vu de l’ensemble des principes de diffusion qui régissent l’échantillonnage par capteur passif, plusieurs modifications, notamment sur la géométrie, ont pu être apportées et constituent l’objet de cette étude au travers du développement de nouveaux capteurs passifs : les DMG (Diffusive MilliGel). Leur synthèse par un système millifluidique leur confère une géométrie unique, constituée de billes ellipsoïdales de dimension millimétrique. Leurs paramètres physico-chimiques ont été caractérisés. Différents paramètres tels que le temps d’exposition et les méthodes d’analyses ont été optimisés. Les DMG ont été testés au cours d’applications environnementales et leur aptitude à échantillonner la fraction labile du cuivre a été mise en évidence. Une première étude dans des eaux douces a permis de mettre en évidence l’influence de la matière organique sur la fraction retenue par DMG, ainsi que l’aptitude de ce capteur à évaluer la toxicité du cuivre. Pour cela, un organisme modèle, Ceriodaphnia dubia, a été exposé dans les mêmes conditions au cours d’une étude écotoxicologique. La comparaison entre les DMG, les DGT et une méthode par colonne de chelex a mis en évidence les avantages qu’offre ce capteur par rapport aux autres techniques. Enfin, une série d’expériences sur les sols viticoles a révélé les aptitudes des DMG à échantillonner du cuivre dans cette matrice complexe. / Repeated use of copper in Bordeaux mixture to fight against mildew has led to an accumulation of this metal in the vineyard soils. To assess the impact of this pollution, the quantification of this element in the soil is essential and more precisely the quantification of the bioavailable fraction which give an indication of the copper toxicity. For that, the passive samplers appear as reliable and efficient tools. However, due to diffusion principles which control the uptake by passive samplers, an optimization of the geometry seems to be necessary and induced this study through the development of a new passive sampler: the DMG (Diffusive MilliGels). The synthesis by millifluidic process confers a unique geometry; DMG are composed of ellipsoidal beads of around 1 mm diameter. First of all, their physico-chemical parameters were characterized and analytical methods and the exposure time were optimized as well. DMG were then tested for an environmental application and their ability to sample the labile fraction of copper was thus demonstrated. Namely, analysis of freshwater by DMG allowed highlighting the influence of organic matter on the fraction retained by this passive sampler and their ability to evaluate the copper toxicity was confirmed. For that, a living organisms Ceriodaphnia dubia was exposed in the same condition during a comparative ecotoxicological study. Moreover, the comparison between DMG, DGT and a Chelex column method showed the advantages of our developed method particularly for in situ application. Finally, a series of experiments on vineyard soils was performed to reveal the abilities of DMG in copper sampling in this complex matrix.
4

Pesticides in the Great Barrier Reef: Monitoring Tools

Melanie Shaw Unknown Date (has links)
Pesticide runoff from agricultural applications poses a potential threat to water quality in the world heritage listed Great Barrier Reef (GBR) and sensitive monitoring tools are needed to facilitate effective monitoring of these pollutants. This thesis has worked to advance passive sampling tools for monitoring trace organic pollutants and their potential impacts on the GBR. The suitability of several available passive sampling tools for detecting trace concentrations of target pesticide analytes was investigated in a laboratory calibration chamber before experiments were conducted to further understanding of the response of Chemcatcher passive samplers in environmental conditions likely to be experienced in the GBR. Passive samplers were deployed in a survey of pesticides in the GBR environment and extracts were applied in bioassays to investigate their application for predicting mixture toxicity to GBR biota. When employed and interpreted appropriately, passive sampling tools have been shown to provide for sensitive and reproducible detection of organic pollutants in relatively pristine environments. While considerable research has been conducted into the performance and theory of analyte uptake by a range of passive sampling devices, several key knowledge gaps existed and were addressed in this study. The applicability of the performance reference compound (PRC) concept as an in situ calibration method for passive samplers using Empore Disk sampling phases (Chemcatchers) to monitor polar compounds was investigated. This experiment showed that while uptake of pesticides was linear and reproducible, PRC loss was not linear, meaning that the dissipation rates of these PRCs cannot be used to estimate the effect of field exposure conditions on uptake rates. An alternative in situ calibration technique using PRC loaded polydimethylsiloxane (PDMS) disks deployed alongside the Chemcatchers as a surrogate calibration phase has been tested and shows promise for future applications. Pesticide concentrations in waters flowing to the GBR have been shown to undergo dramatic fluctuations over short time periods and the potential for these conditions to limit the integrative period of sampling was investigated by simulating a changing concentration event in a calibration chamber. The ability for samplers to predict average concentrations was dependant on the deployment configuration (with or without membrane) used and the period of deployment relative to the changing concentration event. Passive samplers were employed in a survey of pesticides in GBR waters during a wet and dry season at river mouths, two nearshore regions and an offshore region. The nearshore marine environment was shown to be contaminated with pesticides in both the dry and wet seasons (average water concentrations of 1.3-3.8 ng L-1 and 2.2-6.4 ng L-1, respectively), while no pesticides were detected further offshore. Continuous monitoring of two rivers over 13 months showed waters flowing to the GBR were contaminated with herbicides (diuron, atrazine, hexazinone) year round, with highest average concentrations present during summer months (350 ng L-1). The use of passive samplers has enabled identification of insecticides in GBR waters which have not been reported in the literature previously. Extracts from passive samplers deployed at three sites in the GBR were applied to bioassays targeting integral life stages or functions of coral reef biota: scleractinian coral larvae, sea urchin larvae, a marine diatom and marine bacteria. The results demonstrate the utility of pairing passive sampling with bioassays and reveal that mixtures of organic pollutants in the GBR have the potential to cause detrimental effects to coral reef biota. This research outlines an approach that reduces one of the levels of simplification of risk assessment of pollutants to ecosystems by incorporating mixtures of chemicals present in the environment. The use of passive sampler extracts in toxicity testing allows pollutant mixtures to be assessed at a range of enrichment factors and, with the inclusion of biota from the ecosystem of concern, improves the relevance of results for predicting real world effects. The findings of this thesis are intended to be used to improve the application of passive sampling tools for routine monitoring to provide managers with understanding of the pesticides present, the potential effects of those pollutant mixtures and feedback on the efficacy of implemented land management practices in halting and reversing the impacts of pesticides on the GBR.
5

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
6

Étude de l'applicabilité des POCIS (Polar Organic Chemical Integrative Sampler) au dosage des résidus de médicaments dans les effluents hospitaliers / Study of the applicability of POCIS (Polar Organic Chemical Integrative Sampler) for monitoring pharmaceuticals in hospital wastewater

Bailly, Emilie 08 April 2013 (has links)
L’évaluation des risques environnementaux et sanitaires liés à la présence de résidus de médicaments dans l’environnement, représente un enjeu majeur en particulier au regard de la gestion du cycle des usages de l’eau. Les effluents des établissements de soins représentent une source non négligeable de pollution et justifient le développement de techniques spécifiques de mesures des émissions de résidus de médicaments dans leurs eaux usées. Dans le cadre de ces développements de méthode, l'échantillonnage représente une des difficultés majeures car la matrice brute des eaux en sortie des hôpitaux est très chargée en matières organiques, les débits sont extrêmement variables, les sites de prélèvement sont difficiles d'accès et il existe une forte variabilité des dispensations des traitements jour/nuit et semaine/week-ends. Les échantillonneurs intégratifs apparus récemment, offrent une alternative intéressante aux stratégies d’échantillonnage existantes, permettant d'effectuer un suivi moyenné sur de longues périodes d'observation associé à une simplicité d'usage et une réduction des coûts. Ce travail porte sur l’étude de l’applicabilité des échantillonneurs intégratifs POCIS (Polar Organic Chemical Integrative Sampler) au dosage des résidus de médicaments dans les effluents hospitaliers. Ce dispositif a principalement été utilisé dans les eaux de surface et les effluents de STEP et son application dans les eaux usées reste rare. 6 molécules déjà identifiées comme représentatives des grandes familles de médicaments utilisés à l'hôpital (Aténolol, Prednisolone, Méthylprednisolone, Sulfaméthoxazole, Ofloxacine, Kétoprofène) ont été retenues.Les cinétiques d’adsorption des molécules sur les POCIS ont été suivies en laboratoire en condition de maitrise des paramètres les plus influents : température, vitesse de l’eau, charge en matière organique, colmatage…Ce calibrage a pour but de déterminer le coefficient d’échantillonnage Rs (L/j) spécifique à chaque molécule et nécessaire au calcul de la concentration dans le milieu d’exposition du POCIS. Nous avons observé une augmentation des Rs quand la vitesse de l'eau augmente ou quand la température augmente. Dans les eaux usées, la valeur de Rs est plus faible et la durée de la phase linéaire est réduite comparée à l'eau du robinet. Pour ce type d'application, la période d'exposition ne devra pas dépasser 4 à 5 jours en raison du colmatage des membranes et d'une teneur élevée en particules organiques dissoutes. Après calibrage dans l’eau du robinet et dans l’eau usée, les POCIS ont été exposés in situ dans un effluent hospitalier pour mesurer les concentrations en 6 molécules ciblées. Cinq ont pu être quantifiées et les concentrations calculées à partir des extraits des POCIS sont concordantes avec celles obtenues par prélèvement direct d’un échantillon moyenné d’eaux usées. Le facteur limitant réside dans les difficultés d’accès au site et la présence de solides dans le collecteur d'eaux usées. Ce travail ouvre des perspectives quant à l'application des POCIS pour les effluents hospitaliers et pourra à terme contribuer à l'acquisition de données pour une meilleure surveillance des rejets. / The assessment of the environmental and public health risks due to pharmaceutical residues, is a main issue particularly in the light of water cycle management and water resources. Hospitals are supposed to be a main source of pollution and the assessment of their contribution to the overall pharmaceutical pollution is necessary. Monitoring the pharmaceutical loads in hospital sewage is a great challenge because of the difficulties which have to be overcome to obtain representative samples: high organic content and suspended solids, wastewater flow variations, difficult access to sampling sites, variations of pharmaceutical release throughout the day resulting from hospital activities. An interesting alternative way is to use passive samplers, which allow for the measurement of Time Weighted Average (TWA) concentrations, overcoming many shortcomings of the spot sampling techniques. The aim of this work is to evaluate the applicability of POCIS for the monitoring of pharmaceuticals in hospital wastewater. This tool is mainly used for surface water or WWTP effluent and its application for wastewater sampling remains scarce. This study was conducted on six compounds already selected as representative of some of the main class of pharmaceuticals used at the hospital (Atenolol, Prednisolone, Methylprednisolone, Sulfamethoxazole, Ofloxacin, Ketoprofen). POCIS were calibrated for the analytes of interest in tap water and wastewater in laboratory conditions close to relevant environmental conditions (temperature, flow velocity, fouling). Sampling rates (Rs) were determined and we observed a significant increase with flow velocity and temperature. Whatever the compound, the Rs value was lower in wastewater and the linear phase of uptake was shorter than in tap water. A five-day period was defined as the optimal duration for POCIS exposition in wastewater.POCIS were then deployed in a hospital sewage pipe during four days and the estimated water concentrations were close to those measured in twenty-four hour composite samples, carried out with an autosampler.This work gives encouraging results for the deployment of POCIS in wastewater that could be a useful tool for pharmaceutical pollution management.
7

Measurements of ozone vertical distribution in a hinoki (Chamaecyparis obtusa) forest using a sensitive ozone passive sampler

TAKENAKA, Chisato, 竹中, 千里, HIBINO, Michiko, 日比野, 道子, KURIYAMA, Haruyo, 栗山, 芳留代 12 1900 (has links) (PDF)
農林水産研究情報センターで作成したPDFファイルを使用している。
8

A Pilot Study of Small-Scale Variations in Outdoor Benzene Concentrations

Fridh, Samantha Catherine 01 January 2011 (has links)
Benzene is an important toxic chemical in urban air and known human carcinogen released substantially by mobile sources. It's important to understand the spatial variation of benzene concentrations in order to understand exposures of susceptible sub-populations such as children and minority groups. Current monitoring networks use large and expensive air samplers that require electricity and restrict the location and number of samplers, not allowing for fine spatial resolution data. The goals of this study are to develop and evaluate protocols for passive sampling and analysis of ambient benzene concentrations, and conduct a pilot study investigating small-scale variations over an area where children are likely to be exposed. Protocols were developed for the use and analysis of the Radiello RAD130 passive sampler for field sampling over the spatial scale of a city park adjacent to an elementary school. A pilot study was conducted from 4/27/11-5/4/11, where 11 samplers were exposed for a seven day sampling period at the park. After sampler exposure, benzene concentrations were determined through solvent desorption followed by analysis using a Varian gas chromatograph with mass spectrometer. Co-location with the existing regulatory active sampler in the county and of two samplers at the same site was done to evaluate the accuracy and precision of the methods, respectively. Health risk estimates were calculated using risk assessment guidance from the U.S. and California Environmental Protection Agencies. Concentrations over the park were found to range from 0.23 0.34 µg m^-3 with a coefficient of variation of 11%. A relative percent difference of 3% was found between the co-located sampler and the active sampler, and a 14% relative percent difference was found between the two duplicate samplers. The variation in health risk from concentration variation due to sampler placement contributed less to the overall uncertainty in the estimates than the uncertainty built in to the calculation parameters of inhalation unit risk and cancer potency factor, as estimated by the U.S. EPA and California EPA, respectively. These results suggest that the exposure of an individual at the park would be characterized sufficiently for standard health risk analysis through the use of one sampler. Further research is necessary into using passive samplers over both the same spatial scale in other areas, as well as on a larger scale to determine intra-urban benzene concentration distributions. The protocols developed here will be used in a future planned study of benzene concentration measurements to characterize neighborhood-scale exposures in Hillsborough County.
9

Predikce průměrných hodinových koncentrací přízemního ozonu z měření pasivními dozimetry / Prediction of mean hourly values of surface ozone concentrations from passive sampler measurements

Sinkulová, Michaela January 2020 (has links)
In terms of air pollution, ground-level ozone is according to current knowledge, contributes the most to damage to ecosystems. To calculate the key indicators of potential damage to ecosystems, such as the exposure index AOT40 and stomatal flux, it is important to know the hourly ozone concentrations, which are the input data for both calculations. For the measurement of O3 air pollution concentrations for the purposes of environmental studies, continuous measurement is not used, but measurement by passive (diffusion) dosimeters, which are exposed for a longer period (usually 1 week-1 month) and thus indicate the average concentration for the relevant longer period. The aim of this diploma thesis is the prediction of hourly concentrations of ground-level ozone from measurements by diffusive samplers, which took place in the period 2006-2010 in Jizerské hory mountains. Monitoring always took place for 2 weeks during the vegetation seasons (April-October) at localities and at various altitudes (714 m above sea level - 1,000 m above sea level). Ogawa diffusive samplers were used. From these average and meteorological concentrations, hourly values of ground-level ozone concentrations were calculated according to the model from professional study and these were compared with measurements from an...
10

Analytical determination of emerging contaminants by using a new graphene-based enrichment material for solid-phase extraction and passive sampling

Liu, Yang 24 March 2020 (has links)
Emerging contaminants represent newly identified organic chemical pollutants that are not yet covered by routine monitoring and regulatory programs. Current research on these contaminants is greatly hindered by the shortage of analytical methods due to the complex matrices, extremely low concentration and their “emerging” nature. In this study the innovative analytical and monitoring methods have been developed and validated for determination of emerging pollutants in water (including pharmaceutical and personal care products, pesticides and artificial sweeteners) based on graphene-silica composite as the solid-phase extraction (SPE) sorbent and as the receiving phase in passive sampler. Graphene, a new allotropic member in the carbon family, has been considered to be a promising candidate for sorption material with high loading capacity because of its ultra-high specific surface area and large delocalized π-electron-rich structure. The composite employed in this work was synthesized by using the cross-link agent to covalently combine carboxylic acid groups of graphene-oxide with the amino groups of the modified silica gel. Afterwards, graphene-silica composite was obtained after treated with hydrothermal reaction in the microwave autoclave, which was demonstrated by X-ray diffraction (XRD). The analytical procedure entails SPE followed by high performance liquid chromatography equipped with tandem mass spectrometers (HPLC-MS/MS). Several crucial parameters were optimized to improve recovery of the analytes, including the amount of sorbents, the ratio of graphene oxide/amino-silica and pH value of water samples. The best recovery results were achieved with 100 mg 10 % (w/w) graphene-silica composite, which were over 70 % except four artificial sweeteners, ranitidine and triclosan. Compared with its commercial counterpart Oasis HLB, pH value variation of water samples has less effect on the recoveries, making graphene composite to be a potential receiving phase of monitoring tool. The batch-to-batch reproducibility was verified on six independently SPE cartridges with graphene-silica composites from two repeatable synthetic batches, showing relative standard deviations (RSDs) in the range of 8.3 % to 19.1 %, except ibuprofen and saccharin. The cartridges proved to be reusable for at least 10 times consecutive extractions, with RSD < 14.9 %, except ibuprofen and diclofenac. The Chemcatcher® passive sampler is frequently used for monitoring polar organic chemicals in surface water. Uptake kinetics is necessary to be quantified to calculate time-weighted average (TWA) concentration. A series of calibration experiments were conducted in the beaker renewal experiments as well as in the flow-through system with styrenedivinylbenzene-cross connect (SDB-XC) disks and graphene-silica composite as the receiving phase. The results obtained from the beaker renewal experiments showed that the uptake kinetics of accumulated compounds with all Chemcatcher® configurations can keep linear within 2 weeks. The innovative configuration using graphene-silica composite powder placed between two PES membranes was able to accumulate eleven of the selected compounds with uptake rate (Rs) from 0.01 L/day (acesulfame K and sucralose) to 0.08 L/day (chlothianidin), while its commercial counterpart SDB-XC disks with polyethersulfone (PES) membranes can accumulate seven substances with Rs from 0.02 L/day (sucralose and chlothianidin) to 0.15 L/day (carbamazepine). In the flow-through system, when Chemcatchers® were equipped with SDB-XC disks without PES membranes, the linear uptake range for the majority of compounds was only in one week, except atrazine. The Rs of accumulated compounds were from 0.16 L/day (chloramphenicol) to 1.04 L/day (metoprolol) that are higher than the same substances in the beaker renewal experiments, in which the Rs of chloramphenicol and metoprolol were 0.09 L/day and 0.56 L/day respectively. However, if the PES membranes were employed, the uptake kinetics in both calibration experimental designs were comparable: the Rs of accumulated compounds from the configuration with SDB-XC disks covered by PES membranes were from 0.035 L/day (sucralose) to 0.17 L/day (carbamazepine) and from the configuration with graphene-silica composite were from 0.01 L/day (gemfibrozil) to 0.08 L/day (chlothianidin). Moreover, the uptake range can keep linear within two weeks. The developed Chemcatcher® method was successfully applied in real surface waters. 1-H benzontriazole, tolyltriazole and caffeine were the main contaminants in Elbe River and the Saidenbach drinking water reservoir. The investigated results between summer and autumn monitoring period were not significantly different.:Acknowledgement I Abstract III Zusammenfassung V Content IX List of Figures XIII List of Tables XVII Table of Abbreviations XIX 1. Motivation 1 2. Introduction 3 2.1 Emerging contaminants 3 2.1.1 Definition 3 2.1.2 Sources 3 2.1.3 Concern about the adverse impacts 5 2.2 Analysis of the emerging contaminants 7 2.2.1 General analytical process 7 2.2.2 Enrichment techniques 8 2.2.2.1 Liquid-liquid extraction (LLE) 8 2.2.2.2 Solid-phase extraction (SPE) 9 2.2.2.3 Innovative type of solid-phase extraction 13 2.2.3 Analytical methods 15 2.3 Graphene and its application in analytical chemistry 19 2.3.1 Introduction 19 2.3.2 Synthesis methods of graphene 20 2.3.3 Application in sample pre-treatment 21 2.3.3.1 Graphene-based material as SPE sorbent 21 2.3.3.2 Graphene-coated fibers as SPME sorbent 22 2.3.3.3 Magnetic graphene as MSPE sorbent 23 2.3.3.4 Graphene-based MIPs 24 2.4 Chemcatcher®—a passive sampling technique 25 2.4.1 Introduction 25 2.4.2 Theory 26 2.4.2.1 Equilibrium passive sampling 27 2.4.2.2 Kinetic passive sampling 28 2.4.3 Concept of Chemcatcher® 28 2.4.4 Calibration of Chemcatcher® 33 2.4.5 Performance and reference compounds 36 3. Study objectives and hypotheses 39 3.1 Study objectives 39 3.2 Hypotheses 41 4. Material and methods 43 4.1 Materials 43 4.1.1 Chemicals and solutions 43 4.1.2 Consumable materials and instruments 44 4.2 Synthesis of graphene-silica composite 46 4.3 SPE experiments 49 4.3.1 Packing method 49 4.3.2 SPE procedure 49 4.3.3 Optimization of SPE procedures 51 4.3.4 Repeatability and reusability test 52 4.4 Chemcatcher® experiments 53 4.4.1 Preparation and precondition 53 4.4.2 Calibration of Chemcatcher® 55 4.4.2.1 Preliminary test 55 4.4.2.2 Experimental design of the beaker batch tests 56 4.4.2.3 Experimental design of the flow-through system 57 4.4.3 Monitoring application of Chemcatcher® in surface water 59 4.4.4 Elution process 60 4.4.5 Statistic data evaluation 61 4.5 HPLC-MS/MS analysis 62 5. Results and discussion 63 5.1 Preparation and characterization of graphene-silica composite 63 5.2 SPE performance of the graphene-silica composite 67 5.2.1 Preliminary test of packing methods 67 5.2.2 Optimization of SPE procedures 68 5.2.2.1 The amount of sorbent 68 5.2.2.2 Graphene ratio in the composites 68 5.2.2.3 pH value of the water sample 69 5.2.3 Repeatability and reusability test 72 5.2.3.1 Performance of the off-line SPE 72 5.2.3.2 Repeatability and reusability test results 75 5.2.4 Summarized discussion of the SPE performance 76 5.3 Calibrating results of Chemcatcher® 86 5.3.1 Pre-test results 86 5.3.1.1 Feasibility test of commercial disks as receiving phase 86 5.3.1.2 Stability test 88 5.3.1.3 Elution optimization. 88 5.3.1.4 Recovery of the filters 92 5.3.2 Calibration results of renewal experiments 93 5.3.2.1 SDB-XC disks without and with membranes 93 5.3.2.2 Graphene-silica composite as receiving phase 97 5.3.3 Calibration results of the flow-through system experiments 101 5.3.3.1 Determination of experimental parameters 101 5.3.3.2 Concentration control 103 5.3.3.3 Calibration results 105 5.3.3.4 Preliminary evaluation of performance and reference compounds 112 5.4 Application of Chemcatcher® in surface water 114 5.5 Discussion about problems of commercial disks as receiving phase in Chemcatcher® 118 5.5.1 Deformation of commercial disks 118 5.5.2 The particles in the solution after elution 119 6. Conclusion and perspective 121 7. Annex 125 7.1 Material and methods 125 7.1.1 Chemicals 125 7.1.2 Silica gel and graphene oxide 144 7.1.3 Microwave reduction program 144 7.1.4 Working schedule of the calibration experiments in flow-through system 144 7.1.5 HPLC-MS/MS conditions 146 7.2 Experimental results 149 7.2.1 Stability of the colloid solution of graphene oxide 149 7.2.2 EDX analysis results 149 7.2.3 HPLC-MS/MS results 152 7.2.4 Calibrating results of the beaker renewal experiment 153 7.2.5 Calibrating results of the flow-through system experiments 157 7.2.6 Monitoring results in the Elbe River 161 Reference 163

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