Persistent pain conditions are a major health problem throughout the world and are one of the primary reasons that people seek medical treatment (Gureje, Von Korff, Simon, & Gater, 1998; Verhaak, Kerssens, Dekker, Sorbi, & Bensing, 1998). These conditions are characterized by complex interactions between cognitive, emotional, and physiological disturbances and are often associated with comorbid psychological disorders (Gatchel, 2004). Though previous studies have examined the effect of interventions targeting persistent pain, such as physical self-regulation interventions, few studies have examined the complex interaction between such interventions and other variables such as psychological and physiological functioning and presence of social support. The current study was designed to evaluate the effect of a physical self-regulation intervention (i.e. diaphragmatic breathing entrainment) on response to a brief physical stressor (i.e., mild thermal stimulation) as well as to evaluate whether presence or absence of a supportive partner influenced this relationship. Participant response was measured via self-report of pain intensity and unpleasantness and via physiological measures of respiration rate, blood pressure, heart rate, and heart rate variability. The study consisted of 154 female participants who participated in pairs (i.e., 77 pairs). Each participant was randomly assigned to training in diaphragmatic breathing or a control condition as well as being randomly assigned to complete the study with or without their supportive partner present. Analyses revealed that breathing entrainment resulted in significantly slower breathing rate during the thermal stressor task (p < .01). Presence of a supportive partner interacted with breathing entrainment to influence heart rate during the thermal stressor task (p < .05) such that participants who completed the study with a support person present had a lower heart rate when trained in diaphragmatic breathing than when trained in a control protocol and participants who did not have a support person present showed the opposite effect. Presence of a supportive partner also interacted with breathing entrainment to influence ratings of task unpleasantness (p < .05) such that participants who were trained in diaphragmatic breathing rated the task similarly regardless of presence or absence of a supportive partner, whereas participants who were trained in a control protocol rated the task as more unpleasant when accompanied by a supportive partner. In conclusion, the present study demonstrates the impact of training in diaphragmatic breathing and presence of social support on response to thermal stimuli as measured by both self-report (i.e., ratings of task unpleasantness) and physiological (i.e., respiration rate and heart rate) measures. This study highlights the usefulness of implementing a self-regulatory training strategy for treatment of pain and in considering the efficacy of incorporating a supportive partner into such training.

In this thesis, we study persistent currents and quantum critical phenomena in the systems of mesoscopic physics. As an introduction in Chapter 1 we familiarize the reader with the area of mesoscopic physics. We explain how mesoscopic systems are different from quantum systems of single atoms and molecules and bulk systems with an Avogadro number of elements. We also describe some important mesoscopic phenomena. One of the mathematical tools that we extensively use in our studies is Random Matrix Theorty. This theory is not a part of standard physics courses and for educational purposes we provide the basics of Random Matrix Theory in Chapter 2. In Chapter 3 we study the persistent current of noninteracting electrons in quantum billiards. We consider simply connected chaotic Robnik-Berry quantum billiard and its annular analog. The electrons move in the presence of a point-like magnetic flux at the center of the billiard. For the simply connected billiard, we find a large diamagnetic contribution to the persistent current at small flux, which is independent of the flux and is proportional to the number of electrons (or equivalently the density since we keep the area fixed). The size of this diamagnetic contribution is much larger than the previously studied mesoscopic fluctuations in the persistent current in the simply connected billiard. This behavior of persistent current can ultimately be traced to the response of the angular-momentum l = 0 levels (neglected in semiclassical expansions) on the unit disk to a point-like flux at its center. We observe the same behavior for the annular billiard when the inner radius is much smaller than the outer one. We also find that the usual fluctuating persistent current and Anderson-like localization due to boundary scattering are seen when the annulus tends to a one-dimensional ring. We explore the conditions for the observability of this phenomenon. In Chapter 4 we study quantum critical phenomena in a system of two coupled quantum dots connected by a hopping bridge. Both the dots and connecting region are assumed to be in universal Random Matrix crossover regimes between Gaussian orthogonal and unitary ensembles (defined in Chapter 2). We exploit a diagrammatic approach appropriate for energy separations much larger than the level spacing, to obtain the ensemble-averaged one- and two-particle Greens functions. We find that two main components of the twoparticle Green’s function (diffuson and Cooperon) can be described by separate scaling functions. We then use this information to investigate a model interacting system in which one dot has an attractive s-wave reduced Bardeen-Cooper-Schrieffer interaction, while the other is noninteracting but subject to an orbital magnetic field. We find that the critical temperature TC of the mean-field transition into the superconducting state in the first dot is non-monotonic in the flux through the second dot in a certain regime of interdot coupling. Likewise, the fluctuation magnetization above the critical temperature is also non-monotonic in this regime, can be either diamagnetic or paramagnetic, and can be deduced from the Cooperon scaling function. We end this thesis with conclusion in Chapter 5.

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

Dislocation channel-veins and persistent slip bands (PSBs) are characteristic dislocation configurations that are of interest to both industry and academia. However, existing mathematical models are not adequate to describe the mechanism of the transition between these two states. In this thesis, a series of models are proposed to give a quantitative description to such a transition. The full problem has been considered from two angles. Firstly, the general motion and instabilities of arbitrary curved dislocations have been studied both analytically and numerically. Then the law of motion and local expansions are used to track the shapes of screw segments moving through channels, which are believed to induce dislocation multiplication by cross-slip. The second approach has been to investigate the collective behavior of a large number of dislocations, both geometrically necessary and otherwise. The traditional method of multiple scales does not apply well to describe the pile-up of two arrays of dislocations of opposite signs on a pair of neighbouring glide planes in two dimensional space. Certain quantities have to be more accurately defined under the multiple-scale coordinates to capture the much more localised resultant stress caused by these dislocation pairs. Through detailed calculations, one-dimensional dipoles can be homogenised to obtain some insightful results both on a local scale where the dipole pattern is the key diagnostic and on a macroscopic scale on which density variations are of most interest. Equilibria of dislocation dipoles in a two-dimensional regular lattice have been also studied. Some natural transitions between different patterns can be found as a result of geometrical instabilities.

Disorders of consciousness (DoC) are a group of disorders that can occur after severe brain injury. DOC have been subdivided based on behavioural observations into: Coma, lacking any signs of wakefulness or awareness; the vegetative state, showing signs of wakefulness but lacking any signs of awareness; and the minimally conscious state, showing signs of wakefulness and infrequent and irregular signs of awareness. The so-called locked-in syndrome, a state where both wakefulness and awareness are intact, but no communication is possible due to a lack of muscle function, does not belong to the disorders of consciousness. However, it is difficult to distinguish the locked-in syndrome from DoC diagnostically, because consciousness can only be shown through consistent responses to a command and current methods for assessing consciousness rely on behavioural responses. Patients with locked-in syndrome might not be able to move voluntarily at all in the most severe cases. Behavioural assessment would then classify them as unaware. While this is an extreme and rare case, it illustrates the problem behavioural assessment poses. Such assessments are unable to distinguish the effects of impaired muscular control from impaired awareness, when either has reached an extreme level of severity. Brain damage that does not affect consciousness itself can nevertheless affect the results of the behavioural assessment of consciousness. It is then hardly surprising that the diagnosis of DoC is associated with a high level of uncertainty. The advantage of brain imaging methods is that they do not rely on the patients ability to produce a consistent behavioural response. There have therefore been efforts to use the brain imaging methods electroencephalography, positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) to aid diagnosis of disorder of consciousness. PET and fMRI have successfully been used to identify regions of difference in some patients in a DoC. Task-based fMRI has been used to identify intact consciousness, using tasks that require explicit understanding of instructions and wilful modulation of brain activity, but no motor control. One of these tasks consists of periods where the participant imagines playing tennis alternated with periods of rest. The ability to follow this paradigm is evidence of consciousness, and a few patients with a diagnosis of DoC have been shown to be able to do this task. However, the tennis task requires high order processing of the tasks requirements and the majority of patients does not respond to this task. fMRI tasks that test sensory modalities instead of consciousness have been used to show retained brain function even in DoC patients that do not respond to the tennis task. In this work the tennis task and a battery of other tasks including tactile, visual and auditory stimulation, were studied on a group of DoC patients. It was found that none of the patients responded to the task of imagining playing tennis, but retained sensory function could be identified in three out of seven patients. This highlights a strength of fMRI, namely that it can identify retained brain function below the level that is necessary for consciousness. However, the results also show that more than half of the patients studied here, did not show retained brain activation during the fMRI scan. For any of the patients that did not show a response, this can be due to an actual lack of retained brain function, but it can also be due to limitations of the task-based fMRI analysis. The fMRI tasks only test one sensory function at a time, for a short time. Thus a visual fMRI task for example, can only provide information about areas of the brain, that are involved in visual processing. And when vigilance is fluctuating, retained brain function can remain undetected, if vigilance is low during the scan. Functional connectivity analysis is a method to study internal connections between brain areas that is not dependent on an external task. It models the brain as a network of interconnected regions and studies the characteristics of this network. Graph theory is a mathematical field that has found application on many other fields using network analysis, like social sciences, metabolic network modelling or gene network modelling. In fMRI analysis, graph theory has been used to study different phenomena and pathologies and global network properties have been shown reproducibly. The work presented here aims to develop new methods based in graph theory aiding the identification of residual brain integrity. To allow an assessment of the brain network topology and its use in the assessment of residual brain integrity, a novel method was designed based on a graph theoretical measure. The method, termed Cortical Hubs And Related network Topology (CHART) is a two stage procedure. The rst stage identifies statistically significant differences in functional connectivity between two groups, using a measure of the average connectivity of each voxel, the weighted global connectivity. The second stage highlights the topology of the networks associated with those differences. Two fMRI datasets, with different underlying tasks and pathologies were used to test the CHART method. The first dataset was acquired from a group of patients with severe depression. It contrasted the state of the brain before and after successful treatment with electroconvulsive therapy. In this patient group the CHART method was able to identify an area of hyperconnectivity in the depressed state, compared to the treated state. This area of hyperconnectivity was connected to areas that had priorly been shown to be overly connected in the depressed state. The second dataset consisted of DoC patients, that had been extensively assessed behaviourally. Half of the patients were diagnosed to be in a vegetative state, the other half was diagnosed to be in a minimally conscious state. The first stage of CHART identified several areas of difference based on the weighted global connectivity. The second stage highlighted that the observed global differences were due to an overall lack of extended functional connectivity in the vegetative state patients. The addition of a healthy control group in stage two allowed comparison not only between the two DoC groups, but also with the healthy group. In summary it was observed that the spatial extent of the connectivity seen in the minimally conscious group resembles the spatial extent of the connectivity seen in the healthy control group, while the spatial extent of connectivity observed in the vegetative state group was minimal, compared to both healthy and minimally conscious group. Thus the spatial extent of connectivity is a distinguishing property for the vegetative state group studied here. However the first stage of the CHART method is a group based method. In disorders of consciousness, where the underlying pathology is different from case to case, this concept is problematic. Finding a meaningful group of interest is difficult or impossible, because lesions differ in location and extent. Individual differences in connectivity can be expected to be large, and a generalisation of the CHART result might not lead to improved diagnosis for every patient. For diagnosis, the patients individual characteristics must be taken into account. An additional objective of this work was therefore to develop a method to compare a single patient to a group of controls. An approach based on regression modelling was tested but failed to provide the necessary statistical sensitivity to detect impaired connectivity. In conclusion the CHART method developed in this work provides insights into the functional connectivity of a group of DoC patients. To assist diagnosis, further development of a method to compare a single subject to a group of controls will be important.

Philosophiae Doctor - PhD / Persistent organic pollutants (POPs) are very tenacious wastewater contaminants with negative impact on the ecosystem. The two major sources of POPs are wastewater from textile industries and pharmaceutical industries. They are known for their recalcitrance and circumvention of nearly all the known wastewater treatment procedures. However, the wastewater treatment methods which applied advanced oxidation processes (AOPs) are documented for their successful remediation of POPs. AOPs are a group of water treatment technologies which is centered on the generation of OH radicals for the purpose of oxidizing recalcitrant organic contaminants content of wastewater to their inert end products. Circumvention of the reported demerits of AOPs such as low degradation efficiency, generation of toxic intermediates, massive sludge production, high energy expenditure and operational cost can be done through the application of the combined AOPs in the wastewater treatment procedure. The resultant mineralisation of the POPs content of wastewater is due to the synergistic effect of the OH radicals produced in the combined AOPs. Hydrodynamic cavitation is the application of the pressure variation in a liquid flowing through the venturi or orifice plates. This results in generation, growth, implosion and subsequent production of OH radicals in the liquid matrix. The generated OH radical in the jet loop hydrodynamic cavitation was applied as a form of advanced oxidation process in combination with hydrogen peroxide, iron (II) oxides or the synthesized green nano zero valent iron (gnZVI) for the treatment of simulated textile and pharmaceutical wastewater.

There has been limited investigation into the nature of specific language impairment (SLI) in adolescence, and even less investigation into speech production in SLI, particularly beyond the preschool years. Phonological output is crucial to oral expressive language, one of the characteristic areas of deficit in SLI. It was hypothesized that adolescents with SLI present with residual speech errors. Accordingly, this study investigated the presence, nature and cause of speech deficits in adolescents with persistent SLI. Adolescents aged 13.0-14.0 years with persistent SLI (n=31) were compared to typically developing (TD) peers (n=31) on an Oral Motor Evaluation (OME) and a Speech Assessment Battery (SAB), consisting of: Multisyllabic Word Repetition, Nonsense Word Repetition, Phrase Repetition, Sentence Repetition and Tongue Twisters. Tasks were analysed in terms of accuracy and the amount of effort required, to determine efficiency and automaticity of phonological output. All participants completed a battery of memory tasks and the language abilities of the SLI group were evaluated. Caregivers completed questionnaires investigating risk factors. Results indicated that adolescents with persistent SLI produced a higher number of inconsistent and context-dependent deviant speech behaviours than TD peers, involving syllable structure changes (phoneme additions/omissions), phoneme substitutions, fluency errors and repetitions/revisions. Participants with SLI also had a higher incidence of neuromotor deficits. Persistent SLI appears to relate to a multifactorial etiology, involving both genetic and early history factors. There was high comorbidity of attention deficits, with implications for resource allocation. Results were interpreted within a functional capacity viewpoint. Speech deficits are thought to contribute to a threshold effect, where even subtle deficits in one area can compromise processing in another area. Speech production in this population appears to be more resource-demanding than in TD peers, which may affect concurrent performance on linguistic and memory tasks. This hypothesis is supported by the high correlation between speech tasks and expressive syntax for SLI participants. The high incidence of speech deficits in adolescents with SLI ii has implications for research and clinical practice with individuals of all ages with SLI.

Dans ce manuscrit, nous présentons des mesures haute résolution de chaleur spécifique Cp réalisées sur des anneaux mésoscopiques d'argent à très basses températures. Le but de cette expérience est de mettre en évidence une possible signature thermique due à la présence de courants permanents. Ce phénomène reste encore mal compris malgré de nombreuses expériences. Il existe en effet des contradictions entre les différents modèles théoriques et les résultats expérimentaux. L'approche thermique que nous exposons ici est un angle nouveau qui n'a jamais été exploré. Sous champ magnétique, une oscillation de période égale au quantum de flux Φ0=h/e (ou moitié) de Cp est attendue théoriquement. L'échantillon étudié est composé d'un grand nombre d'anneaux d'argent mésoscopiques déposés sur une membrane en silicium suspendue. Nous avons réalisé, à différentes températures, de multiples balayages en champ de la chaleur spécifique. Un traitement des signaux obtenus a ensuite été réalisé afin de repérer une éventuelle périodicité. Il a révélé la présence sur le signal de phase d'une oscillation de période h/2e n'apparaissant pas sur le module de la chaleur spécifique. Cette signature est maximale à 100mK. La fréquence et l'amplitude obtenues sont en accord avec les prédictions théoriques. La sensibilité atteinte est de ΔC~10^(-14)J/K sur le module (et de Δφ~10^(-2) degrés sur la phase) soit 10^(-21)J/K par anneau. Les résultats présentés ici apportent donc de nouveaux éléments dans l'analyse des courants permanents. / In this thesis, we report very high resolution specific heat measurements of normal metal mesoscopic silver rings at very low temperatures. The objective of this experiment is to measure the possible existence of thermal signatures due to the presence of persistent currents. This phenomenon is still misunderstood despite many measurements. Some contradictions exist between experimental results and the different theories. The thermal approach is a new point of view. Under magnetic field, the Cp variation is expected be periodic with the quantum of flux Φ0=h/e or half of the quantum of flux as it has been theoretically predicted. The studied samples is composed by a large number of silver rings with an electronic phase coherence length of few microns at low temperatures. They were deposited on the suspended membrane of a silicon sensor. We have realized, at different temperatures, a large number of identical scans of the heat capacity variation as a function of the applied field. A signal processing work on this data has then been realized to detect signal periodicities. It showed a difference between the module and the phase of the heat capacity. A peak can be observed on the FFT at a frequency corresponding to h/2e on the phase signal. The peak appears particularly at 100mK with a amplitude which is consistent with previous calculations. A sensitivity of ΔC~10^(-14)J/K on the module (Δφ~10^(-2) degrees on the phase) has been reached whether 10^(-21)J/K per ring. Thus, the presented experiences give new elements in the field of persistent currents.

In Image Classification, pictures of the same type of object can have very different pixel values. Traditional norm-based metrics therefore fail to identify objectsin the same category. Topology is a branch of mathematics that deals with homeomorphic spaces, by discarding length. With topology, we can discover patterns in the image that are invariant to rotation, translation and warping. Persistent Homology is a new approach in Applied Topology that studies the presence of continuous regions and holes in an image. It has been used successfully for image segmentation and classification [12]. However, current approaches in image classification require a grayscale image to generate the persistence modules. This means information encoded in colour channels is lost. This thesis investigates whether the information in the red, green and blue colour channels of an RGB image hold additional information that could help algorithms classify pictures. We apply two recent methods, one by Adams [2] and the other by Hofer [25], on the CUB-200-2011 birds dataset [40] andfind that Hofer’s method produces significant results. Additionally, a modified method based on Hofer that uses the RGB colour channels produces significantly better results than the baseline, with over 48 % of images correctly classified, compared to 44 % and with a more significant improvement at lower resolutions.This indicates that colour channels do provide significant new information and generating one persistence module per colour channel is a viable approach to RGB image classification.

A distribuição espacial e o histórico deposicional de poluentes orgânicos persistentes (POPs) em sedimentos foram avaliados no ecossistema marino-estuarino da Ilha do Marajó, Pará. Os pesticidas predominantes nos sedimentos da camada superficial foram os HCHs (<0,04 e 0,90 ng g-1) e DDTs (<0,02 - 2,72 ng g-1), em peso seco. PCBs e PBDEs não foram detectados. HCHs predominaram no Estuário do Rio Paracauari indicando uso recente provavelmente relacionado à atividade madeireira. DDTs foram detectados na Praia do Pesqueiro e nos testemunhos sedimentares (<0,02 - 12,31 ng g-1 peso seco) do Mercado, Fazenda e Paracauari. Os valores máximos de DDT ocorreram entre 1982 e 2008 e são associados com campanhas de saúde púbica. Há uma redução gradativa até o presente que coincide com a substituição do DDT por piretróides. A razão &#931;DDDs / &#931;DDEs, predominantemente < 1, indicou a ocorrência de processos decomposicionais aeróbicos. No geral, as condições ambientais não favorecem o acúmulo de pesticidas nos sedimentos, sendo que os valores estão abaixo do limite provável para causar efeitos adversos exceto para HCHs no Estuário do Rio Paracauari. O presente trabalho estabeleceu a distribuição de POPs na Ilha do Marajó e poderá contribuir para o processo de gestão costeira e ambiental da região. / The spatial distribution and depositional history of persistent organic pollutants (POPs) in sediments were evaluated in marino-estuarine ecosystem of Marajó Island, Pará. The predominant pesticides in sediments of the surface layer were HCHs (<0.04 and 0, 90 ng g-1) and DDTS (<0.02 to 2.72 ng g-1) by dry weight. PCBs and PBDEs weren\'t detected. HCHs predominated in Paracauari Estuary indicating recent use probably related to logging. DDTs were detected in Praia do Pesqueiro and sediment cores (<0.02 to 12.31 ng g-1 dry weight) Mercado, Fazenda and Paracauari. Maximum levels of DDT residues occurred between 1982 and 2008 and are associated with pubic health campaigns. There is a gradual reduction up to the present which coincides with the substitution of the DDTs by pyrethroids. The ratio &#931;DDDs / &#931;DDEs predominantly < 1 indicated the occurrence of decomposicional processes under aerobic conditions. Overall, the environmental conditions do not favor the accumulation of pesticides in sediments, and the values are below the threshold likely to cause adverse effects except for HCHs in Paracauari Estuary. This work established the distribution of POPs in Marajó Island and could contribute to the process of coastal and environmental management in the region.