Non-Aqueous Phase Liquids (NAPLs) include commonly occurring organic contaminants such as gasoline, diesel fuel and chlorinated solvents. When released to subsurface environments their spreading is a complex process of multi-component, multi-phase flow. This work has strived to develop new models and methods to describe the spreading of NAPLs in heterogeneous geological media. For two-phase systems, infiltration and immobilisation of NAPL in stochastically heterogeneous, water-saturated media were investigated. First, a methodology to continuously measure NAPL saturations in space and time in a two-dimensional experiment setup, using multiple-energy x-ray-attenuation techniques, was developed. Second, a set of experiments on NAPL infiltration in carefully designed structures of well-known stochastic heterogeneity were conducted. Three detailed data-sets were generated and the importance of heterogeneity for both flow and the immobilised NAPL architecture was demonstrated. Third, the laboratory experiments were modelled with a continuum- and Darcy’s-law-based multi-phase flow model. Different models for the capillary pressure (Pc) – fluid saturation (S) – relative permeability (kr) constitutive relations were compared and tested against experimental observations. A method to account for NAPL immobility in dead-end pore-spaces during drainage was introduced and the importance of accounting for hysteresis and NAPL entrapment in the constitutive relations was demonstrated. NAPL migration in three-phase, water-NAPL-air systems was also studied. Different constitutive relations used in modelling of three-phase flow were analysed and compared to existing laboratory data. To improve model performance, a new formulation for the saturation dependence of tortuosity was introduced and different scaling options for the Pc-S relations were investigated. Finally, a method to model the spreading of multi-constituent contaminants using a single-component multi-phase model was developed. With the method, the migration behaviour of individual constituents in a mixture, e.g. benzene in gasoline, could be studied, which was demonstrated in a modelling study of a gasoline spill in connection with a transport accident. / Flerfasföroreningar innefattar vanligt förekommande organiska vätskor som bensin, dieselolja och klorerade lösningsmedel. Spridningen av dessa föroreningar i mark är komplicerad och styrs av det samtidiga flödet av organisk vätska, vatten och markluft samt utbytet av komponenter (föroreningar) mellan de olika faserna. Detta arbete syftade till att utveckla nya metoder och modeller för att studera spridningen av flerfasföroreningar i mark: (i) En metodik utvecklades för att i laboratorium noggrant och kontinuerligt mäta hur en organisk vätska är rumsligt fördelad i en tvådimensionell experimentuppställning. Metoden baserades på röntgenutsläckning för olika energinivåer. (ii) Infiltration av organisk vätska i vattenmättade medier studerades för olika konfigurationer av geologisk heterogenitet. I experimentuppställningen packades olika sandmaterial noggrant för att konstruera en välkänd, stokastiskt heterogen struktur. Spridningsprocessen dokumenterades i tre detaljerade mätserier och heterogenitetens påverkan på flöde och kvarhållning av den organiska vätskan påvisades. (iii) Experimenten simulerades med en numerisk modell. Olika modeller prövades för att beskriva de grundläggande relationerna mellan kapillärtryck (Pc) vätskehalt (S) och relativ permeabilitet (kr) för detta tvåfassystem av vatten och organisk vätska. En relation infördes för att beskriva partiell orörlighet hos den organiska vätskan i porer vars halsar tillfälligt blockeras av vatten då mediet avvattnas. Vikten av att i de grundläggande relationerna ta hänsyn till hysteresis och kvarhållning av organisk fas visades. (iv) Olika Pc-S-kr relationer för trefassystem av vatten, organisk vätska och markluft testades mot befintliga experimentella data. En ny relation för hur slingrigheten (eng. tortuosity) beror av vätskehalten infördes i kr-S relationen och olika möjligheter för att skala Pc-S relationen analyserades. (v) En modelleringsmetodik utvecklades för att studera spridningen av flerkomponentsföroreningar. Med metoden kunde spridningsbeteendet hos enskilda, särskilt skadliga komponenter som t.ex. bensen särskiljas då ett bensinutsläpp i samband med en transportolycka simulerades.

Traditionally, the sea has been considered as the ultimate sink of most pollutions, due to its huge volume and assimilating capacities, and the coastal waters, because of their intermediate position between deep seas and human activities, has been acting as a buffer zone. However, during the past years, the interest in environmental issues in general, and in the conservation of the water quality in coastal regions, in particular, has steadily increased. For coastal waters, this growing interest can be related to the increase in population and industrial activity along rivers and on coastal areas, which poses an important threat on coastal ecosystems, and may limit the use of coastal waters for human activity. This problem is drastically increased during the tourist season, when a large number of tourists tend to favour coastal resorts. Although at different scales, both the discharge of wastewater from a marine outfall or the discharge of nutrient- or sediment-laden freshwater from a river play an important role in many physical, chemical and biological processes, which in turn may affect the human use (recreational, economical, etc), of coastal waters. It is important, therefore, to be able to model these processes in order to optimise the multiple uses of coastal waters, accommodating the economical interests to marine production and recreation. The present thesis describes the development, validation and application to real cases of a three-dimensional numerical model for substance (pollution) transport in coastal waters, which can be applied to a wide range of situations, as marine outfall discharges, river freshwater discharges or sediment transport. The three-dimensional advection-diffusion equation is solved using a random walk Lagrangian particle formulation, in which the substance to be transported is divided into discrete "packets" that are moved around due to the effects of the transport mechanisms relevant in coastal waters. Transport induced by currents, waves, and turbulent diffusion is included in the model calculations, together with other mechanisms such as sediment settling and resuspension, buoyancy effects due to density differences, and microbiological inactivation. Specific formulations have been developed to account for the transport due to the initial discharge velocity, for buoyant transport in the frame of particle models in waterbodies, for sediment resuspension, and to increase the efficiency of the model by uncoupling the nearfield modelling from that of the farfield. Concentration distributions are obtained at the end of the simulation by mapping the position of the resulting set of discrete particles onto the nodes of a grid, that may be deformable, employing different optional methods. This transport model has been validated using several test cases of known analytical solution, and has been applied to a series of real cases for which numerical results could be compared to observational evidence (such as experimental data, video recordings and satellite images). The comparison yields a good agreement between observational evidence and modelled data, and reveals that the model can be applied to a wide range of transport problems in various environments.

As apex predators in coastal systems, bottlenose dolphins (Tursiops truncatus) are susceptible to persistent organic pollutant (POP) accumulation and retention over time, which has prompted continued interest in understanding the extent to which contaminant body burdens or other stressors are sufficient to cause adverse sublethal effects on energetic fitness, immune function, or reproduction. Increasing our knowledge of reproductive endocrinology in bottlenose dolphins may provide insight into changes in reproductive rates, thereby expanding the capacity to assess conservation status. This study used the Enzyme-Linked ImmunoSorbent Assay (ELISA) technique to examine peptide fertility hormones [inhibin A, inhibin B and anti-Müllerian hormone (AMH)] measured in serum of free-ranging dolphins (n = 129) of varying age, gender, and maturity status from three locations (Sarasota Bay, FL, Indian River Lagoon, FL, and southern Georgia). The primary research objectives were to establish hormone baselines, investigate AMH and inhibin use as reproductive biomarkers, and examine the potential use of these hormones as biomarkers of toxicant or other stressor effects on reproduction. AMH secretion differed significantly with gender (p < 0.001), where levels were approximately 1,000-fold higher in males than females (1,122 ± 427 ng mL-1 and 1.15 ± 1.25 ng mL-1, mean ± SD). Male AMH levels were related to maturity status, and linear regression analysis revealed a significant, negative relationship between male AMH and age, body length, body weight, and maximum girth in all populations. Of the parameters assessed, age was the best indicator of AMH levels in males. AMH concentrations in females did not vary significantly over time or with maturity status, but exhibited a decrease in some older individuals, potentially indicating an AMH decline in long-lived female dolphins. Inhibins did not differ significantly between age classes in males, but appeared to be an estrous cycle indicator in females, where inhibin peaks were likely related to follicular and luteal phases. These data provide new information on circulating serum AMH and inhibin levels in bottlenose dolphins, which appear to reflect a degree of gonadal function and show promise as reproductive biomarkers. Our findings suggest the possibility of toxicant effects on AMH and inhibin production, but not conclusively. Further investigation of mechanism(s) of action for contaminant-related reproductive toxicity will elucidate the diagnostic value of these hormones to assess the effects of POPs on fertility potential in bottlenose dolphins.

Based on many years of water quality (including algal) and water treatment cost data, available at Umgeni Water, a study was undertaken to better understand the water quality relationships in man made lakes within the company's operational area, and to investigate how water quality affected the cost of treating water from these lakes. The broad aims to the study were to: identify the key environmental variables that were affecting algal populations in lakes; and if these were significant to establish predictive models relating algae to the water quality; and to develop models relating the water quality in lakes to the cost of treating water from the lakes. Semi-quantitative models were developed relating algal abundances with important environmental variables. In most cases, the models developed were related to algal populations that were known to adversely affect water treatment. Direct algal impact on water treatment processes was through the production of either taste and odour forming compounds (requiring advanced water treatment, such as use of activated carbon), or their ability to clog sand filters and so reduce filter run times (requiring more frequent backwashing of filters). Thereafter lake water quality parameters (which included water physico-chemistry and algae) were investigated to determine which factors were most significantly impacting on water treatment and hence treatment costs at selected water works (WW) within the Umgeni Water operational area. Models were developed relating raw water quality entering respective water works with costs incurred in treating that water. The models allowed simulations to be developed illustrating how changes in water quality might impact on water treatment costs. The impact of eutrophication and contamination of rivers and lakes, and its subsequent impact on surface water resources, was quantified. / Thesis (Ph.D. (Botany))--North-West University, Potchefstroom Campus, 2004.

Based on many years of water quality (including algal) and water treatment cost data, available at Umgeni Water, a study was undertaken to better understand the water quality relationships in man made lakes within the company's operational area, and to investigate how water quality affected the cost of treating water from these lakes. The broad aims to the study were to: identify the key environmental variables that were affecting algal populations in lakes; and if these were significant to establish predictive models relating algae to the water quality; and to develop models relating the water quality in lakes to the cost of treating water from the lakes. Semi-quantitative models were developed relating algal abundances with important environmental variables. In most cases, the models developed were related to algal populations that were known to adversely affect water treatment. Direct algal impact on water treatment processes was through the production of either taste and odour forming compounds (requiring advanced water treatment, such as use of activated carbon), or their ability to clog sand filters and so reduce filter run times (requiring more frequent backwashing of filters). Thereafter lake water quality parameters (which included water physico-chemistry and algae) were investigated to determine which factors were most significantly impacting on water treatment and hence treatment costs at selected water works (WW) within the Umgeni Water operational area. Models were developed relating raw water quality entering respective water works with costs incurred in treating that water. The models allowed simulations to be developed illustrating how changes in water quality might impact on water treatment costs. The impact of eutrophication and contamination of rivers and lakes, and its subsequent impact on surface water resources, was quantified. / Thesis (Ph.D. (Botany))--North-West University, Potchefstroom Campus, 2004.

Els compostos orgànics persistents (COPs) són tòxics, persistents, bioacumulables, tenen una gran estabilitat química i capacitat per distribuir-se per tot el planeta. La contaminació per aquests compostos en diversos trams del riu Ebre és molt elevada en comparació als nivells descrits a la Península Ibèrica i en sistemes d'aigües continentals del món, principalment a causa de l'activitat de les plantes clor-àlcali de Flix (província de Tarragona) i Montsó (província d'Osca). Aquesta tesi estudia l'impacte que les plantes clor-àlcali de Flix i Montsó han tingut en el tram baix de la conca del riu Ebre. Primerament avalua la dispersió atmosfèrica dels contaminants emesos a Flix. En segon lloc estudia la mobilitat dels sediments contaminants dipositats a l'embassament de Flix aigües avall del riu i l'impacte en l'activitat agrícola d'aquest tram de riu. Finalment caracteritza els residus de DDT del tram baix de la conca del riu Ebre i determina l'origen d'aquest pesticida, actualment prohibit a l'Estat espanyol.Dispersió atmosfèrica de contaminants emesos per la planta de Flix (Capítol 2)S'ha avaluat la dispersió atmosfèrica de COPs mitjançant l'anàlisi d'aquests contaminants en vegetació. S'ha observat que l'activitat industrial que es desenvolupa a Flix actua com a font de contaminació atmosfèrica de COPs. S'ha obtingut un model de distribució per a cada contaminant que ha permès determinar un radi d'influència per a cadascun d'ells. La dispersió de cada contaminant va estretament lligada a les seves propietats físico-químiques. Impacte de la planta de Flix en l'activitat agrícola del tram baix de la conca del riu Ebre (Capítol 3)S'ha estudiat el contingut de COPs en 85 finques agrícoles regades amb aigua del riu Ebre des de Flix fins a la desembocadura i s'ha avaluat la transferència de COPs d'aquests sòls a la part comestible dels productes agrícoles que s'hi cultiven. S'han observat nivells de COPs en els sòls agrícoles molt variables però en general les concentracions són baixes. Els sòls amb nivells més alts són aquells que estan situats a prop del llit de riu o bé aquells que es reguen amb quantitats molt elevades d'aigua. La presència de COPs a la part comestible dels productes agrícoles no està directament lligada a la presència de COPs en el sòl a on s'han cultivat. Els nivells de COPs dels productes agrícoles provenen de la incorporació directa de la part aèria de la planta.Mobilització dels contaminants de l'embassament de Flix aigües avall del riu Ebre (Capítol 4)S'han analitzat mostres de sediments fluvials del mateix embassament de Flix i d'aigües avall fins al Delta de l'Ebre. S'han observat concentracions molt altes de tots els COPs estudiats excepte els HCHs als sediments de l'entorn de Flix i en cap cas s'observa una disminució de les concentracions respecte les campanyes anteriors. Existeix mobilització i transport dels sediments contaminats de Flix aigües avall d'aquest punt i s'han mantingut constants durant aquest període de temps. Origen dels residus de DDT de la conca del riu Ebre (Capítol 5)El DDT és un producte sintètic amb propietats insecticides. El seu ús i producció està restringit des de la dècada dels 70, encara que la prohibició total a l'Estat espanyol no va tenir lloc fins l'any 1994. Tanmateix, actualment encara es detecten quantitats importants de DDT i els seus productes de degradació, DDE i DDD, en sòls, aire, aigua, etc. S'han analitzat els nivells dels isòmers de DDT en mostres de sòls i sediments del tram baix de la conca del riu Ebre per tal de fer una caracterització d'aquests residus. A més s'ha determinat la composició enantiomèrica de l' o,p'-DDT d'aquests sòls per conèixer el seu estat de degradació. S'han identificat almenys dues fonts de contaminació per DDTs relacionades amb l'activitat industrial de Flix i Montsó. A més a més s'han identificat àrees amb aportacions recents de DDT, algunes d'elles relacionades amb l'ús de l'acaricida dicofol. / Persistent Organic Pollutants (POPs) are compounds which have shown to be toxic, persistent, bioaccumulable in animals and humans and with capacity of worldwide atmospheric transport, reaching remote areas where they have never been produced or used. In some specific areas such as the Ebre river basin, contamination by POPs is very high, mainly due to the industrial activity from two chlorine-alkali plants situated in Flix (Tarragona Province, Catalonia) and Monzón (Huesca Province, Aragón). The present PhD thesis is devoted to assess the impact that this chlorine-alkali plants has had in the lower course of the Ebre river basin. Firstly it evaluates the atmospheric emissions to the environment from the chlorine-alkali factory in Flix. Secondly it studies the mobilization downstream of the polluted sediments placed in Flix water reservoir and the impact of these industrial discharges in the agricultural soils irrigated with water collected downstream. It must be remembered that agriculture encompasses one of the main uses of river water in the Ebre river basin. Finally, the thesis is addressed to characterize the DDT residues in sediments and soils of the lower course of the Ebre river basin and to determine the origin of this pesticide that is currently banned in Spain.

Machines operating in dusty environments, such as mining and civil works, are prone to premature failure, leading to production losses. To address this problem, this research project examines the interaction between solid contaminants and the bearing micro-geometry, in lubricated surface contacts. In particular, it seeks to identify anti-wear additives that are effective in reducing wear under abrasive conditions, making machine elements more dirt tolerant. In general, the influence of antiwear additive is so small that it is difficult to isolate it. Manufactures often make claims about their antiwear products, which are difficult to verify. Hence, there is a need to characterising the antiwear additives available with a well-defined parameter, making it easier for consumers to compare the efficacy of various additives, and be able to select the most suitable additive for a given environment. Effect of micro-geometry parameters such as radial clearance, out-of-roughness and surface roughness was examined and a Film Shape Factor (FSF) – also termed gamma ratio – has been proposed for ensuring adequate separation of journal bearings operating in hydrodynamic lubrication regime, where the out-of-roundness values are higher than the surface roughness values. In this research, an experimental study has been conducted on journal bearings, to examine the influence of five antiwear additives on the bearing wear and micro-geometry. The test additives were provided by the industry partner without revealing their chemical identity or composition; however, these included some of the most commonly used antiwear additives. The tests were performed under three conditions: pure base oil, base oil containing contaminants, and base oil containing contaminants treated with five different additives. The experiments were aimed at choosing one wear measuring technique that evaluates the performance of an individual additive reliably, and based on this technique the additives were characterised. To achieve these objectives, a multi-wear parameter approach (MWPA) was developed, which employed three main wear measurement methodologies, i.e. weight loss, micro-geometry and particle counts –to examine the effect of the antiwear additives. Minimum oil film thickness was also measured to study the lubrication status in the bearing contacts. The MWPA helped in comparing different wear measuring methods, and in selecting the most reliable one. This approach also helped in developing short duration wear tests, thereby saving time, while still getting reliable results without repeating these. Wear experiments were performed on seven sets of bronze bearings and steel sleeve shafts. The test contaminant was 16 micron Aluminium oxide Al2O3 powder mixed in oil with 4% concentration by weight. These solid contaminants were treated with five different antiwear additives to study their influence on the bearings. Bearings were operated such that the minimum oil film thickness in the bearing was equal to the size of the contaminants. These tests were run for a constant sliding distance of 7536m. The results showed that most of the wear measuring techniques do not suit heavily contaminated test conditions. However, the out-of-roundness technique proved to be the most reliable and practical. Based on this technique a methodology was developed which gave a wear characteristic number (N). A unique value of N can be derived for each additive, thereby ranking the additives for their efficacy. The finding of this research provides a better understanding of the methodologies used for measuring wear in journal bearings subjected to dusty environments, and examines the efficacy of each one of these. The wear characteristic number (N) can be used by manufacturers with support from international standards organisations, so that the users can confidently choose the most appropriate antiwear additive for their application. Machines operating in a dusty environment, such as mining industry and civil works are prone to premature failure with subsequent production losses. In response to this problem, this research project examines the interaction between solid contaminant particles and the lubricant film micro-geometry in lubricated surface contacts. In particular, it seeks to identify lubricant anti-wear additives, which are effective in reducing wear under abrasive conditions and thus making machine elements more dirt tolerant.

This research is the outcome of investigations of the ability of Nitella congesta, a charophyte, to hyperaccumulate metal contaminants, as well as contribute to the sustainable development of a chain of lakes derived from the sand mine voids at Capel 250km south of Perth, Western Australia. Studies were conducted to ascertain the taxonomy of Nitella congesta as well as its life cycle pattern in relation to the hydrological regime of the lakes of the wetlands. It was observed that a decrease in the availability of water in the lakes particularly on the onset of summer, initiated the production of fruiting bodies whiles prolonged availability of water ensured a prolonged vegetative growth. / Aquatic plants play an important role in the structuring of freshwater communities. Freshwater macrophytes such as Nitella congesta have been reported to serve as food source as well as provide refuge and shelter for macroinvertebrates. Thus the presence of freshwater macrophytes in one way or the other has a direct impact on the species abundance and diversity of macroinvertebrates that use them as their habitat. A study of the impact of Nitella congesta as a suitable macrophyte on diversity and abundance of macroinvertebrates showed a positive outcome. It was observed that species richness and diversity were high in Nitella congesta dominated sites of the lakes. Experimental outcome showed that Nitella congesta is a hyperaccumulator of metals. Both the mucilage and the thallus displayed concentrations of few metals. / The disappearance of submerged macrophytes such as charophytes in shallow lakes is a major problem caused by eutrophication. There has been an approved proposal to discharge treated waste water with a phosphorus concentration of about 4,000μg/L into the lakes of the Capel Wetlands Centre. This necessitated a study of the impact of eutrophication on the establishment of Nitella congesta as a functional macrophyte for the enhancement of the ecological structure of the wetlands. / Results showed that though eutrophication will initially increase the primary productivity of the lakes of the wetlands, the eventual consequence will be the loss of Nitella congesta as a functional macrophyte in the wetlands. / At the last stage of the study, a consistent decrease in pH readings of the lakes and lack of successful germination of Nitella congesta as a result of prolonged drought and exposure of the lake sediment was observed. This necessitated a thorough study of the impact of climate change on the establishment of Nitella congesta in the wetlands. In conclusion, it was observed that Nitella congesta could serve as a suitable tool for the rehabilitation of the wetlands.

[Truncated abstract] This thesis explores the risk factors and perinatal outcomes associated with prelabour rupture of membranes, with a particular focus on the environmental context. Prelabour rupture of membranes is defined as the rupture of fetal membranes before the onset of labour. It is a relatively common obstetric endpoint, occurring in approximately 8-10% of pregnant women at term (PROM) and in up to 40% of all preterm deliveries (pPROM). Despite the high prevalence of the condition, the biological mechanisms and risk factors, and in particular the role of environmental predictors, behind the development of PROM and pPROM remain largely unclear. A record-based prevalence design was used to analyse a population of 16,229 nulliparous, Caucasian women residing in Perth, Western Australia who gave birth to a single newborn during 2002-2004. Maternal age, socioeconomic status and threatened preterm labour during pregnancy were identified as risk factors for prelabour rupture of membranes. Term PROM was significantly associated with fetal distress (OR 1.19; 95%CI 1.00-1.43) and post-partum haemorrhage (OR 1.99; 95%CI 1.60-2.48). A number of perinatal complications were observed to be associated with the presentation of preterm PROM, including prolapsed cord (OR 13.95; 95%CI 4.57-42.61), ante-partum haemorrhage (OR 3.29; 95%CI 2.20-4.91), post-partum haemorrhage (OR 2.12; 95%CI 1.54-2.91), low birth weight (OR 17.79; 95%CI 13.87-22.82), very low birth weight (OR 20.01; 95%CI 14.12-28.35) and stillbirth (OR 5.42; 95%CI 2.87-10.21). However, the outcomes were similar between pPROM patients and other preterm deliveries, indicating that the complications arose due to the timing of the delivery. In contrast though, the risk factors between the two outcomes varied which may suggest that a different aetiological pathway exists between preterm PROM and other preterm deliveries. The frequency of complications decreased with increasing gestational age at delivery until the pregnancy reached full-term, whereupon an increase in gestational age at delivery resulted in an increased risk of fetal distress and post-partum haemorrhage. This finding is novel and may have important implications for the management of prelabour rupture of membranes, specifically with regard to the relative risks and benefits of expectant management (that is, the patient is admitted to an obstetric facility or hospital and closely monitored) versus planned delivery. ... This study represents the first attempt to investigate the potential associations between environmental risk factors and prelabour rupture of membranes. The results of the thesis provide a substantial contribution to our knowledge on prelabour rupture of membranes, including findings of direct relevance to clinical practice as well as a potentially contributing environmental exposure pathway. These original findings suggest a possible preventative approach to reducing the occurrence and associated morbidity of prelabour rupture of membranes may be feasible, and should be pursued if future research confirms the preliminary findings of this thesis.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / The presence of organic contaminants in the environment and in food have become a major concern due to the harmful effects to living organisms. Such contaminants may be pesticides used in agriculture for the control of pests, transformation products formed in the environment or through chemical processes, such as water treatment, and more recently pharmaceuticals and personal care products. Therefore, it is necessary to use sample preparation procedures and detection systems able to detect a variety of organic contaminants in trace level present in complex matrices, such as food and environmental samples. Thus, this study aims to: (1) address the use of high resolution mass spectrometry (HRMS) for the identification and quantification of organic contaminants in fish fillet using two acquisition data modes (full scan and all ions MS/MS) and to optimize QuEChERS method as sample preparation (PAPER 1); (2) present a second quantitative application of the use of QuEChERS method and HRMS for fruit samples (apple, pear and grape) in full scan mode, as well as to apply the proposed method for commercial fruit samples (PAPER 2) and (3) optimize and use QuEChERS method for extracting ionophore antimicrobials in poultry litter, followed by its quantification by LC-MS/MS and identification of transformation products by LC-QToF/MS after three different composting processes (PAPER 3). The three papers presented the importance of sample preparation optimization, QuEChERS, in order to obtain proper recovery of organic contaminants, besides to minimize the matrix effects caused by interferences in the extract. As the use of HRMS, which proved to be a very effective analytical tool for combining high resolution and mass accuracy, for identification and quantification of target organic contaminants, transformation products and metabolites in complex matrices using a rapid chromatographic run. / A presença de contaminantes orgânicos no meio ambiente e em alimentos têm se tornado uma grande preocupação devido aos efeitos nocivos aos seres vivos. Tais contaminantes podem ser desde agrotóxicos empregados na agricultura para o controle de pragas, produtos de transformação formados no meio ambiente ou através de processos químicos, como o tratamento de água, e mais recentemente fármacos e produtos de cuidado pessoal. Com isso, tem-se a necessidade de empregar procedimentos de preparo de amostra e sistemas de detecção capazes de detectar uma variedade de contaminantes orgânicos em nível de traços presentes em matrizes complexas como alimentos e amostras ambientais. Portanto, o presente trabalho tem como objetivos: (1) abordar o emprego da espectrometria de massas de alta resolução (HRMS) para a identificação e quantificação de contaminantes orgânicos em filé de peixe utilizando dois modos de aquisição de dados (full scan e all ions MS/MS) e otimizar o método QuEChERS para o preparo da amostra (ARTIGO 1); (2) apresentar uma segunda aplicação quantitativa do uso de QuEChERS e HRMS para amostras de frutas (maçã, pera e uva) no modo full scan, bem como aplicar o método proposto em amostras reais de frutas (ARTIGO 2) e (3) otimizar e empregar o método QuEChERS para a extração de antimicrobianos ionóforos em cama de frango, seguido de quantificação por LC-MS/MS e identificação de produtos de transformação por LC-QToF/MS após três diferentes processos de compostagem (ARTIGO 3). Os três artigos apresentados abordam a importância da otimização do procedimento de preparo de amostra, QuEChERS, a fim de obter recuperação adequada de contaminantes orgânicos, além de minimizar os efeitos de matriz causados pelos interferentes presentes no extrato. Assim como o uso de HRMS, a qual demonstrou ser uma ferramenta analítica bastante eficiente, por combinar alta resolução e exatidão de massa, para identificação e quantificação de contaminantes orgânicos alvo, produtos de transformação e metabólitos em matrizes complexas utilizando uma análise cromatográfica rápida.