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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

Elucidating Factors that Impact the Removal of Organic Microconstituents by Ammonia Oxidizing and Heterotrophic Bacteria

Khunjar, Wendell O'Neil 22 January 2010 (has links)
Although wastewater treatment plants are a line of defense in minimizing indiscriminate output of microconstituents to natural waters, we do not possess a fundamental understanding of the mechanisms involved in microconstituent removal during wastewater treatment. With this in mind, experiments were designed to investigate the factors that can influence the fate of four microconstituents, carbamazepine (CBZ), 17alpha-ethinylestradiol (EE2), iopromide (IOP), and trimethoprim (TMP), during biological suspended culture treatment. Specifically, the role that various ecological members of biological treatment systems play in biotransforming these compounds was evaluated. Sorption assays were performed with inactivated biomass samples (ammonia oxidizing bacteria (AOB), laboratory enriched heterotrophic cultures free of active nitrifiers with low (Ox⁻) or high (Ox⁺) oxygenase activity, and a nitrifying activated sludge (NAS) from a full-scale wastewater treatment plant) to determine whether partitioning dictates removal of individual microconstituents. No microconstituents sorbed to the AOB culture. Neither CBZ nor IOP sorbed to Ox⁻, Ox⁺ and NAS cultures; however, EE2 and TMP sorbed to the Ox⁻, Ox⁺ and NAS biomass. Sorption was positively influenced by the presence of exopolymeric substances (EPS) associated with the cultures. The protein content of EPS affected EE2 and TMP sorption more appreciably than the polysaccharide content of EPS. Further experiments were performed to investigate microconstituent biodegradation by AOBs, Ox⁻ and Ox⁺ cultures. The influence of growth state and oxygenase activity on biotransformation by each culture was also evaluated. Results indicate that EE2 was the only microconstituent that was amenable to biotransformation by batch cultured AOB and heterotrophic cultures. EE2 was biotransformed but not mineralized by AOB chemostat and batch cultures. TMP was not transformed by AOB batch or chemostat cultures; however both EE2 and TMP were transformed by Ox⁻ and Ox⁺ chemostat cultures. Radiolabeled studies showed that EE2 was mineralized by this culture. Kinetically, AOBs dominated EE2 transformation to monohydroxylated metabolites; however, both Ox⁻ and Ox⁺ cultures further degraded and mineralized EE2 and metabolites generated by AOBs. These results indicate that biotransformation of EE2 by NAS may be limited by heterotrophic activity whereas TMP fate may be a function of heterotrophic activity only. Oxygenase activity did not limit EE2 or TMP biotransformation in chemostat cultures. Subsequent experiments that were performed to identify the factors that influence heterotrophic degradation of EE2 and TMP indicated that the presence of readily biodegradable substrates slows EE2 and TMP biotransformation. The impact of slowly biodegradable substrates like EPS on EE2 and TMP degradation was unclear. These results suggest that EE2 and TMP are most amenable to biodegradation in bioreactors where endogenous conditions dominate. / Ph. D.
292

Evaluating Agricultural Best Management Practices to Mitigate Neonicotinoid Transport in Water and Soil

Maris, Jacob Ogden 17 August 2022 (has links)
The use of agrochemicals, like neonicotinoid insecticides can threaten human and environmental health when they are transported from agricultural fields. To minimize environmental impact of neonicotinoid pesticides to non-target organisms, it is important to quantify the movement of neonicotinoids from agricultural fields and examine how conventional agricultural practices can be altered using best management practices to minimize neonicotinoid transport. We developed a proportional runoff sampler that is inexpensive, rugged, and adaptable to existing runoff quantification systems. The sampler accurately collected flow-weighted samples under a broad range of steady-state and variable flow conditions. We then incorporated the sampler, along with leachate and soil sampling techniques, in a two-year field study testing the effects of winter cover crops and different edge-of-field buffer strip plant types on movement of the neonicotinoid thiamethoxam (TMX) and its metabolite clothianidin (CLO) in treated agricultural fields. Due to dry weather and other complications, runoff and leachate data could not be statistically analyzed. Soil samples indicated that cover crops had no effect on insecticide retention, so cover crops may not be a viable strategy to prevent neonicotinoid transport. Soil TMX was higher in grass buffers than native forb buffers in 2020; however, this result was not repeated in 2021 when vegetative cover was more consistent across treatments. CLO concentration did not vary by buffer in either year. Therefore, buffer strip plant type may have less impact on TMX and CLO retention than other factors like plant density. / Master of Science / Since the 1950's high yield crops and the use of pesticides and fertilizers have helped farmers increase yields from agricultural land. Increased yields have helped food production keep pace with population growth, but the use of pesticides and fertilizers can pose a threat to human and environmental health. Neonicotinoid insecticides can kill not only agricultural pests but beneficial invertebrates like bees and butterflies when the pesticides leave agricultural fields. To lessen environmental impact of neonicotinoid pesticides to the environment, it is important to understand 1) how these insecticides move from agricultural fields, and 2) how conventional agricultural practices can be altered to minimize neonicotinoid transport. We first developed a runoff sampler that was inexpensive, low maintenance, and adaptable to existing systems used to measure runoff. The sampler collects water at a rate proportional to the runoff rate under constant and changing flow rates. We then used the sampler along with leachate and soil sampling techniques in a field study testing the effect of winter cover crops and the species planted in edge-of-field vegetated buffer strips on the amount of the neonicotinoid thiamethoxam (TMX) and its degradation product clothianidin (CLO) remaining in the soil of treated fields during two growing seasons. Due to dry weather and other complications, runoff and leachate data could not be statistically analyzed. Cover crops did not change soil pesticide concentration either year, so cover crops may not be a viable strategy for preventing neonicotinoid transport. Soil TMX was higher in grass buffers than native forb buffers in 2020; however, this result was not detected in 2021 when plant growth in buffers was more uniform across treatments. CLO concentration did not vary by buffer type in either year. Therefore, the species planted in buffer strips may not be as important to holding TMX and CLO in soils as other factors like plant density.
293

Controls on Mixing and Non-Mixing Dependent Denitrification in River Hyporheic Zones

Young, Katherine Irene 28 February 2014 (has links)
Increases in reactive nitrogen from human actions have led to negative impacts on surface water (SW) and groundwater (GW) quality, and it is important to better understand denitrification processes in aquatic systems. The hyporheic zone has unique biogeochemical conditions, and is known to attenuate contaminants originating from SW and traveling through the hyporheic zone, together with necessary reactants. However, the ability of the hyporheic zone to attenuate contaminants from deeper upwelling GW plumes as they exit to SW is less understood. I used MODFLOW and SEAM3D to simulate hyporheic flow cells induced by riverbed dunes and upwelling GW together with mixing dependent denitrification of an upwelling nitrate (NO3-) plume. My basecase model scenario entailed dissolved organic carbon (DOC) and dissolved oxygen (DO) advecting from SW and DO and NO3- advecting from GW, which is typical of water in agricultural land uses. I conducted a sensitivity analysis to determine controls on mixing dependent denitrification. Mixing dependent denitrification increased with increasing hydraulic conductivity, decreasing lower bottom flux, as well as increasing DOC in SW and NO3- in GW. Non-mixing dependent denitrification also occurred when there was SW NO3-, and I found its magnitude was much greater than mixing dependent denitrification. Nevertheless, potential for hyporheic zones to attenuate upwelling NO3- plumes seems to be substantial, though highly variable depending on biogeochemical reaction rates as well as geomorphic, hydraulic and biogeochemical conditions. Stream and river restoration efforts may be able to increase both mixing and non-mixing dependent reactions by increasing hyporheic zone residence times. / Master of Science
294

Effect of Unsteady Surface Water Hydraulics on Mixing-Dependent Hyporheic Denitrification in Riverbed Dunes

Eastes, Lauren Ann 23 August 2018 (has links)
Increased reactive nitrogen from human activities negatively affects surface water (SW) quality. The hyporheic zone, where SW and groundwater interact, possesses unique biogeochemical conditions that can attenuate contaminants (e.g., denitrification), including mixing-dependent reactions that require components from both water sources. Previous research has explored mixing-dependent denitrification in the hyporheic zone but did not address the effects of varying SW depth as would occur from storms, tides, dam operation, and varying seasons. We simulated steady and unsteady hyporheic flow and transport through a riverbed dune using MODFLOW and SEAM3D, and varied SW depth, degree of sediment heterogeneity, amplitude and frequency of sinusoidal fluctuations, among others to determine these effects. We found that increasing steady state surface water depth from 0.1 to 1.0 m increased non-mixing dependent aerobic respiration by 270% and mixing-dependent denitrification by 78% in homogeneous sediment. Heterogeneous hydraulic conductivity fields yielded similar results, with increases in consumption due to variation in correlation length and variance of less than 5%. Daily SW fluctuation, including variation of amplitude, period, and sinusoidal versus instantaneous changes had significantly less impact than longer-term trends in SW depth. There is potential for the hyporheic zone to attenuate NO3- in upwelling groundwater plumes. Restoration efforts may be able to maximize the potential for mixing-dependent reactions in the hyporheic zone by increasing residence times. / Master of Science / Increased nitrogen in runoff from human activities negatively affects surface water quality. The hyporheic zone is where surface water and groundwater interact, and the mixing between the waters can help to this nitrogen to undergo reaction (denitrification), potentially stopping the contaminant from spreading. Previous research has explored this idea, but has not addressed the impact of varying surface water depth, as would realistically occur due to storms, tides, dam operation, and varying seasons. We simulated both constant and fluctuating surface water conditions on a riverbed dune to see the effects on hyporheic flow and denitrification. Test variables included the surface water depth, the degree of sediment heterogeneity, the amplitude and frequency of surface water fluctuations. We found that increasing the steady-state surface water depth had the most dramatic increase on the amount of reaction undergone. This trend was also seen in heterogeneous sediment. Any daily-scale surface water fluctuations, including runs that varied the amplitude, period, and sinusoidal vs instantaneous changes in surface water depth, had significantly less impact than longer-term trends in surface water depth.
295

Disseny d'immunosensors basats en format homogeni-heterogeni. Aplicació a la determinació de residus orgànics

Jornet Olivé, Maria Dolors 30 July 2010 (has links)
La determinación y control de contaminantes orgánicos ha despertado gran interés en los últimos años. Estos compuestos se acumulan en los ecosistemas terrestres y acuáticos, cosa que los hace especialmente perjudiciales para la salud humana i para el medioambiente. Entre estos contaminantes orgánicos encontramos plaguicidas, compuestos organometálicos, perfluoratos y bromatos, hormonas, fármacos y productos de higiene personal (PPCP). En el campo medioambiental, caracterizado por tener matrices complejas con multitud de contaminantes a nivel de trazas, se ha hecho necesario mejorar la mayoría de procedimientos analíticos per poder determinar-los de forma más eficaz. Los métodos de análisis que utilizan inmunosensores presentan una serie de ventajas en comparación con las técnicas clásicas de análisis per la naturaleza de la señal así como por su diseño y configuración. Los sensores permiten una integración total del proceso analítico hasta el punto de poder obtener la información necesaria in situ en tiempo real. En esta tesis se ha desarrollado un nuevo formato de ensayo llamado homogéneo-heterogéneo (H-H) se ha aplicado a un sistema inmunosensor que ha hecho posible la determinación de residuos de contaminantes orgánicos en agua. En el immunosenor H-H la reacción inmunoquímica de competición entre el analito y el trazador para unirse al anticuerpo se da en fase líquida (fase homogénea). Posteriormente, los productos de esta se separan mediante una fase estacionaria denominada de acceso restringido (RAM). Entre los estudiados, los soportes ADS C18 y C4 acontecen los óptimos para la separación de los inmunoreactivos, consiguiendo que el trazador libre (Hp*) quede atrapado en la fase reversa interna de los soportes RAM y el inmunocomplejo (Ab-Hp*) eluya de forma que se pueda detectar directamente. En este inmunosensor H-H se han de utilizar marcadores de pequeño tamaño que puedan ser atrapados en el interior de los poros de los materiales de acceso restringido. Por esta razón, fue necesario el uso de trazadores no enzimáticos, estableciendo una vía de marcaje de fluoróforos a haptenos con carácter general basada en la utilización de oligonucleótidos derivatizados con los fluoróforo. Para mejorar la sensibilidad se utilizaron dos estrategias: columnas RAM en serie y trazadores con más relación de marcaje. Los resultados fueron satisfactorios consiguiendo determinar atrazina en aguas per debajo de los LMR. El immunosensor H-H es aplicó, con resultados satisfactorios, a dos familias de compuestos (triazinas y sulfonamidas), demostrando la utilidad analítica en muestras representativas. / Jornet Olivé, MD. (2010). Disseny d'immunosensors basats en format homogeni-heterogeni. Aplicació a la determinació de residus orgànics [Tesis doctoral]. Editorial Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/8497
296

The Occurrence and Fate of Steroid Hormones from Manure Amended Agriculture Fields

Sosienski, Theresa Ann 14 July 2017 (has links)
Hormones are endocrine disrupting compounds, which have been shown to alter the sexual development of aquatic organisms. Animal manure applications to agricultural fields for nutrient management can be a source of environmental hormones. This dissertation investigates the occurrence of hormones in fields applied with various manures and their adjacent streams, as well as the effect of manure application technologies on the fate of hormones in soils, sediments, and runoff. A total of 11 hormone compounds were studied. All studied analytes were quantified using liquid chromatography and triple-quadrupole mass spectrometry following various sample extraction and clean-up strategies. The spatial and temporal distribution of manure-associated hormones in a manure surface applied agricultural field and adjacent stream was studied at time points up to 7.5 months after a routine manure application. Hormones were detected mainly in the top 0-5cm soils. Significantly higher levels of hormones were found in the drystack applied area of the field when compared to dairy manure slurry applied portion. New technologies for the subsurface application of poultry litter show promise as a tool to reduce the transportation of environmental hormones in surface runoff. Once adequate sampling protocols were established; it was determined that subsurface injection of both dairy manure and poultry litter reduced the impact of manure surface runoff. Hormones also showed little vertical and lateral movement in the soil. The transformation rates of 1,4-androstadiene-3,17-dione, 4-androstene-3,17-dione and estrone were studied comparing the effects of temperature, soil type, and application type. The calculated half-life of 1,4-androstadiene-3,17-dione in poultry litter surface-applied soils was 1.9 times higher than that in the poultry litter subsurface-injected soils, indicating a faster dissipation rate in the injection slits. Estrone persisted at detectable levels for the duration of the study in all treatments. The continued use of best management practices and innovative manure management techniques for the reduction of nutrients, sediment and other contaminants has the potential to also reduce hormone transport to the natural environment. Monitoring many different types of hormones in all areas of an environmental system will continue to provide better information on the occurrence and fate of hormones sourced from manure amended soils. / Ph. D. / Hormones can contaminate streams and cause harm in the environment by interfering with the sexual development of aquatic organisms. Hormones are naturally occurring in animal manure, which is applied to agricultural fields for nutrients. Animal manures are usually spread on the surface of the soil and hormones can travel from the field to the streams when it rains. There are new technologies where the manure is injected into the soil instead of spread on the surface that could reduce the environmental impact of hormones in manure. This dissertation investigated the how hormones behave in fields applied with animal manures using the surface application technique and the subsurface injection technique. We investigated how long hormones persist in the soil, and their levels in manures, runoff from precipitation, and in waterways. Hormones were shown to stay in the top 0-5cm of soil, and to remain in the manure injection slit, showing that they do not easily move in the environment. Hormones were only detected in runoff water from soils that had surface applied manures. The transformation rate of hormones that were found at the highest levels in all the manures analyzed in this research was studied. It was determined that manure subsurface injection caused one of the compounds to transform at a faster rate in the soil. Overall, hormones were detected for up to 9 weeks in soils that were applied with animal manures. Best management practices such as manure subsurface injection and using a buffer zone between an agricultural field and a stream are promising tools for preventing hormones in animal manure from entering the natural environment.
297

Emerging Contaminants: Occurrence of ECs in Two Virginia Counties Private Well Water Supplies and Their Removal from Secondary Wastewater Effluent

Vesely, William C. 29 June 2018 (has links)
Emerging contaminants (ECs) are chemicals such as pharmaceuticals and personal care products that have been detected in various environmental matrices, including drinking water supplies at trace concentrations (ng/L-ug/L or ng/kg-ug/kg). Current wastewater treatment plant technology is largely ineffective at removing ECs. The objectives of this investigation were to: 1) determine the occurrence of ECs in private well water supplies in Montgomery and Roanoke County, VA 2) quantify the concentrations of three ECs in selected private water supplies; 3) examine the relationship between water quality constituents (nitrate, bacteria, pH and total dissolved solids) to EC occurrence in private water supplies; and 4) determine the ability of the MicroEvapTM, a novel wastewater treatment technology, to remove ECs from secondary wastewater effluent. In partnership with the Virginia Household Water Quality Program, 57 private water supplies were sampled and tested for the occurrence of 142 ECs and 43 other water quality constituents. Up to 73 ECs were detected in the sampled private water supplies. Higher numbers of ECs detected in the tested private water supplies were related with nitrate >1 mg/L, total dissolved solids >250 mg/L, and the presence of total coliform bacteria. Results indicate the MicroEvapTM technology had >99% removal effectiveness for all 26 tested ECs from three secondary wastewater effluent. With the increasing detection of ECs in water bodies, it is essential to understand the occurrence of ECs and environmental predictors of EC presence in different water matrices and continue to develop water treatment technology capable of treating wastewater for EC removal. / Master of Science / Emerging contaminants (ECs) are compounds intended to improve human and animal well-being, and include pharmaceuticals, personal care products, and human/veterinary antibiotics. ECs have been frequently detected in water resources worldwide including drinking water. The release of ECs from wastewater treatment plant (WWTP) effluent is their primary route into the environment. The inability of most current wastewater treatment technologies to fully remove ECs necessitates further development of technology that can effectively remove ECs. Emerging contaminants such as pharmaceuticals enter WWTPs because the human body does not fully metabolize the compound and the remainder exits in waste. Private well water is largely unregulated and often untreated and has been relatively less evaluated for EC presence in the literature. The objectives of this study were 1) determine the occurrence of ECs in private well water supplies in Montgomery and Roanoke County, VA 2) quantify the concentrations of three ECs in selected private water supplies; 3) examine the relationship between well age and depth and water quality constituents (nitrate, bacteria, pH and total dissolved solids) to EC occurrence in private water supplies; and 4) determine the ability of the MicroEvap™, a novel wastewater treatment technology, to remove ECs from secondary wastewater effluent. Emerging contaminants were detected in southwest Virginia private well water. Knowing the ECs present in private well water is necessary to allow for eventual human risk assessment of ECs for people consuming the water. The MicroEvap™ was highly effective at EC removal from wastewater with removal rates >99%. The removal of all ECs from wastewater is essential to ensure purified WWTP effluent. The continued detection of ECs and the unknown human health risks from these contaminants in drinking water means ECs are a significant pollution concern that requires continued assessment.
298

Développement d’une méthode d’extraction des contaminants émergents dans les solides particulaires par LDTD-APCI-MS/MS

Darwano, Hicham 11 1900 (has links)
Douze contaminants émergents (composés pharmaceutiques, pesticides et hormones) ont été quantifiés et extraits de l'eau de rivières et d’échantillons d'eaux usées municipales. La séparation des solides en suspension est effectuée par filtration des échantillons d'eau. L'effet de filtration sur les concentrations de contaminants dissous a été évaluée afin de minimiser les pertes de composés cibles. Les échantillons ont été lyophilisés et ont été extraits en deux cycles par ultrasons combinés avec une étape de nettoyage sur cartouche d’extraction de type C18. La quantification a été réalisée en utilisant la spectrométrie de masse. Les recouvrements de la méthode pour tous les composés ont varié de 68 à 112% dans toutes les matrices étudiées, sauf pour le sulfaméthoxazole et le diclofénac où des recouvrements plus modestes ont été obtenus (38 à 85%). Les limites de détection pour les 12 analytes dans les sédiments et particules en suspension (SPM) de la rivière variaient de 0,7 à 9,4 ng g-1 et de 21 à 92 ng g-1, pour les échantillons SPM de station d'épuration. Tous les contaminants émergents cibles ont été détectés à des concentrations variant de 3 à 5440 ng g-1 dans les matrices étudiées, les concentrations les plus élevées ont été observées dans les échantillons SPM de stations d'épuration. Une partie importante de certains de ces contaminants est clairement associée aux sédiments de rivière ou aux particules en suspension. L’optimisation des processus de traitement de l'eau et le devenir environnemental doit absolument tenir compte de la fraction de contaminants qui liée à des particules si on espère avoir un bilan de masse raisonnable. / We developed a protocol to quantify 12 emerging contaminants (pharmaceuticals and hormones) and pesticides extracted from suspended particulate matter (SPM) of river water and municipal wastewaters samples. The separation of suspended solids was carried through filtration of water samples. We tested a series of 6 different filter types. The effect of filtration on the concentrations of dissolved contaminants was evaluated in order to minimize losses of target compounds. The river bottom sediments samples were lyophilized and both SPM and sediment samples were subjected to ultrasonic extraction combined with C18 cartridge clean-up. Quantifications were realized using mass spectrometry. The overall method recoveries of all compounds ranged from 38 to 112 % in all studied matrices, poor recoveries were achieved for sulfamethoxazole and diclofenac (recoveries for all other compounds in the wastewater treatment plant (WWTP) samples were 68 to 111%). The detection limits in sediments and SPM from river samples for the 12 analytes varied from 0.7 to 9.4 ng g-1 and from 21 to 92 ng g-1 for WWTP SPM samples. All target emerging contaminants were detected with concentrations ranging from 3 to 5440 ng g-1 in the studied matrices, with the highest concentrations observed in WWTP SPM samples. A significant portion of some of those contaminants is clearly associated with bottom sediments or suspended particulates. Optimization of water treatment processes and environmental fate must absolutely consider the fraction of contaminants which is particulate-bound if one hopes to have a reasonable mass balance.
299

Dégradation chimique et biologique de neuf contaminants émergents dans les eaux de surfaces et les effluents primaires d’eaux usées municipales

Cormier, Guillaume 04 1900 (has links)
Un protocole inspiré du test de simulation 309 de l’Organisation de coopération et de développement économiques (OCDE) nous a permis de mesurer la dégradation chimique (excluant la photolyse) dans des eaux de surface de même que la dégradation chimique et biologique de neuf contaminants émergents dans l’effluent d’un décanteur primaire d’eau usée municipale. Les données étaient compatibles avec le modèle de cinétique de pseudo ordre un. Les résultats démontrant une persistance de plus d’un an dans les eaux de surface et de 71 jours dans l’effluent du décanteur primaire suggèrent que les dégradations chimique et biologique ne contribuent pas significativement à la diminution de: atrazine, déséthylatrazine, carbamazépine et diclofénac dans la phase aqueuse des systèmes testés. Les autres composés se sont dégradés à différents niveaux. Le 17ß-estradiol ainsi que l’éthinylestradiol, la noréthindrone, la caféine et le sulfaméthoxazole ont tous été sujet à la dégradation biologique dans les effluents du décanteur primaire d’eau usée avec des constantes de dégradation k et des demi-vies t1/2 mesurées allant respectivement de 0.0082 à 0.59 j-1 et de 1.2 à 85 jours. Les paramètres de cinétique mesurés peuvent être combinés aux concentrations typiques des composés à l’étude dans un décanteur primaire d’eau usée pour y calculer leur vitesse de dégradation. Cependant, puisque les décanteurs primaires dans les usines de traitement d’eaux usées ont généralement des temps de résidence de quelques heures seulement, il est improbable que les neufs contaminants émergents à l’étude diminuent significativement par ces processus durant leur passage dans le compartiment. / A protocol inspired by the OECD 309 simulation test allowed us to measure the chemical (excluding photolysis) degradation in surface waters as well as the chemical and biological degradation potential of 9 emerging contaminants in urban primary settling tank (PST) effluents. The data confirmed that a pseudo first order kinetic model provided a good fit. The results suggest that chemical and biological degradation will not significantly contribute to the disappearance of atrazine, desethylatrazine, carbamazepine and sulfamethoxazole in the aqueous phase of the tested systems given the reported persistency of more than a year in surface waters and 71 days in PST effluents. Other compounds were more easily degraded and 17ß-estradiol, ethinylestradiol, norethindrone, caffeine and sulfamethoxazole were all amenable to biological degradation in PST effluents, with measured degradation rate constants k and half-lives ranging respectively from 0.0082-0.59 d-1 and 1.2-85 days. Since PSTs in WWTPs generally have a water residence time of a few hours and considering the typical concentrations of such ECs’ in those compartments, it is unlikely that significant disappearance will occur during their passage through the PST.
300

Développement d’une méthode multi-résidu pour l’analyse de contaminants émergents dans des échantillons solides et liquides à partir de la spectrométrie de masse à haute résolution

Comtois-Marotte, Simon 04 1900 (has links)
L’analyse des contaminants émergents (ECs) suscite l’intérêt de la communauté scientifique, de sorte que plusieurs études ont rapporté leur présence dans les eaux usées et dans les eaux de surface. Toutefois, la plupart des études ont concentré leurs travaux principalement sur la phase dissoute, si bien que la concentration des ECSs dans les particules en suspension (SPM – suspended particulate matter) demeure peu connue. De plus, la plupart des méthodes traitant l’analyse des ECs sont basées sur le couplage de la chromatographie liquide couplée à un triple quadripôle (QqQ). Typiquement, ces QqQ fonctionnent à basse résolution, augmentant ainsi la probabilité d’obtenir des faux positifs. Afin de diminuer le taux de faux positifs un nouveau protocole permettant l’analyse de 31 ECs dans la fraction dissoute et la fraction solide a été développé à l’aide de la spectrométrie de masse à haute résolution. De plus, un dépistage du potentiel estrogénique par des levures a été effectué. Cela représente l’un des premiers rapports décrivant les concentrations en ECs dans les eaux usées et les SPM combiné avec un dépistage du potentiel estrogénique. La séparation des particules en suspension a été réalisée via la filtration des échantillons liquides. Les ECs ont été extraits de la fraction solide à l’aide d’ultrasons en utilisant du MeOH : ACN (1:1, v/v) avec l’ajout de 1% de HCOOH. Par la suite, l’extrait de la fraction solide et de la phase aqueuse ont été soumis à la SPE (solid phase extraction – extraction sur phase solide) à l’aide d’une cartouche polymérique composé d’acide benzènesulfonique. Une colonne de type C-18 a été utilisée pour séparer les ECs sélectionnés. Un spectromètre de masse de haute résolution (Q-Exactive), constitué d’un quadripôle et d’une trappe ionique orbitale à haute résolution a été utilisé en mode balayage (FS, full scan) avec une résolution de 70 000 FWHM (FWHM– Largeur à mi-hauteur, Full width at half maximum) à m/z 200 pour l’analyse de la fraction solide et en mode suivi des réactions parallèles (PRM, Parallel reaction monitoring) à 17 500 FWHM à m/z 200 pour la fraction liquide. Une ionisation chimique à pression atmosphérique (APCI, Atmospheric pressure chemical ionisation) en modes positif et négatif a été utilisée. La méthode a été appliquée sur des échantillons réels afin de déterminer non seulement la portion d’ECs sur les SPM, mais également leur devenir dans le traitement des eaux usées jusqu’à leur déversement dans les eaux réceptrices. La récupération des composés d’intérêt a été de 27 à 102 % et de 43 à 122%, pour la fraction solide et liquide respectivement. Les limites de détections se situaient entre 0.5 à 104 ng L-1 et de 0.3 à 2.3 ng g-1. Les courbes d’étalonnages dans les matrices d’eaux usées et les solides ont montré une bonne linéarité (R2 > 0.991) pour les analytes cibles ainsi qu’une précision acceptable avec des coefficients de variation inférieurs à 25%. / The trace analysis of emerging contaminants (ECs) is gaining more interest and several studies have widely reported their occurrence in waste and surface water. However, most studies found in the literature reported concentrations only in the dissolved phase often without considering the suspended particulate matter (SPM). Moreover, most of the methods dealing with the analysis of ECs are based on liquid chromatography tandem mass spectrometry with a triple quadruple (QqQ). The majority of QqQ operate at low resolution, thus increasing the possibility of false positive identification. The current study presents a new protocol to quantify 31 emerging contaminants not only in the effluent wastewater, but also from SPM of municipal wastewater samples using high-resolution mass spectrometry, an improvement to reduce false positives. Furthermore, Yeast estrogen screen assay (YES-assay) adapted from direct measurement of estrogenic activity was tested on filtered wastewater samples. This represents one of the first reports describing ECs in wastewater and SPM with direct measurement of estrogenic activity. The separation of suspended particulate matter was realized using filtered water samples. The ECs were extracted from the matrix by sonication using MeOH:ACN (1:1, v/v) with 1% HCOOH. Thereafter, the extracts of the solid fraction and the aqueous phase were subjected to an off-line solid phase extraction (SPE) with a Strata-X-C cartridge to concentrate and clean-up the extracts. A C18 chromatography column was used to separate ECs. A QExactive mass spectrometer, which combines a quadruple analyser with a high resolution orbital ion trap (OrbitrapTM) was used in full scan (FS) mode with 70 000 FWHM (Full width at half maximum) at m/z 200 for analysis of the solid fraction, while analysis of the liquid fraction was realised using parallel reaction monitoring (PRM) with 17 500 FWHM at m/z 200. An APCI (Atmospheric Pressure Chemical Ionization) source in positive and negative mode was used for the ionization of target compounds. The method was successfully applied to real samples allowing us to determine the proportion of ECs in suspended particulate and the fate of the selected ECs during wastewater-treatment processes and their release into receiving surface waters. Recoveries of target compounds ranged from 27 to 102 % and from 43 to 122 % for the liquid and the solid fraction respectively. The limits of detection ranged from 0.5 to 104 ng L-1 and from 0.3 to 2.3 ng g-1. Calibration curves in wastewater and solid matrix showed good linearity (R2 > 0.991), for all target analytes, and precision (intraday and interday) showed coefficients of variation below 25%.

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