Les pesticides sont aujourd’hui reconnus comme ayant des effets néfastes sur l’environnement et sur la santé humaine. La surveillance du niveau de pollution par les pesticides dans les écosystèmes aquatiques implique la mise en place d’une stratégie d’échantillonnage basée sur des prélèvements ponctuels, suivi d’une étape de traitement et d’analyse des échantillons. Par ailleurs, la concentration de ces polluants est sujette à de nombreuses fluctuations et par conséquent une faible fréquence d’échantillonnage ne donne pas une image représentative du réel niveau de pollution et de l’évolution de la qualité des masses d’eau.Ainsi, ce travail de recherche porte sur une méthode alternative d’échantillonnage basée sur l’utilisation d’échantillonneurs passifs, afin de suivre le niveau de contamination des eaux de surface et souterraines par les pesticides. Deux types d’échantillonneurs passifs, les Chemcatchers (version polaire) et les POCIS (Polar Organic Chemical Intégrative Sampler), ont été étudiés afin de comparer leurs efficacités comme outils de diagnostic et de surveillance de la pollution des milieux aquatiques par les pesticides polaires. La première phase de l’étude concerne la validation de ces outils, basée sur la calibration en laboratoire et in-situ des POCIS et des Chemcatchers, afin de permettre leurs utilisations en tant qu’outils d’analyse quantitative pour l’évaluation de la concentration moyenne des pesticides dans les masses d’eau. La deuxième partie du travail est plus orientée sur l’applicabilité de ces échantillonneurs passifs pour l’étude de la distribution spatiale des pesticides, de l’identification des sources de pollution et du transfert des polluants (eau de surface/eau souterraine). / Nowadays, pesticides are recognized as having adverse effects on the environment and human health. Monitoring the level of pesticides pollution in aquatic ecosystems involves the establishment of a sampling strategy based on a water spot sampling, followed by a stage of processing and analysis of samples. Furthermore, the concentration of these pollutants can fluctuate over time and therefore a low sampling frequency does not give a representative picture of the real level of pollution and cannot describe faithfully the changing of the quality of the water bodies.Thus, this work focuses on an alternative sampling method based on the use of passive samplers to monitor the level of contamination of surface and groundwater by pesticides. Two types of passive samplers, the polar Chemcatcher and the POCIS (Polar Organic Chemical Intégrative Sampler) were studied in order to compare the effectiveness of these tools for the diagnosis and the monitoring of aquatic pollution by polar pesticides.The first step of the study consists the validation of these two passive samplers, which is based on the laboratory and in-situ calibration of POCIS and polar Chemcatcher, to allow their use as tools for quantitative analysis for the assessment of the average concentration of pesticides in water bodies. The second part of the work is more focused on the applicability of these passive samplers for the study of the spatial distribution of pesticides, the identification of pollution sources and the assessment of pollutants transfer (surface water/groundwater).

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In recent years, the scientific community has expressed interest in the ability to observe global climate indicators such as polar sea ice. Advances in microwave remote sensing technology have allowed a large-scale and detailed study of sea ice characteristics. This thesis provides the analysis and development of sea ice mapping algorithms for the SeaWinds scatterometer. First, an in-depth analysis of the Remund Long (RL) algorithm for SeaWinds is performed. From this study, several improvements are made to the RL algorithm which enhance its performance. In addition, a new method for automated polar sea ice mapping is developed for the SeaWinds instrument. This method is rooted in Bayes decision theory, and incorporates an adaptive model for seasonally fluctuating sea ice and ocean microwave signatures. The new approach is compared to the RL algorithm, to passive microwave data, and to high-resolution SAR imagery for validation.

Pregnant polar bears (Ursus maritimus) construct maternal dens out of snow in the autumn where they give birth to and raise altricial young. In recent years, there has been a decrease in polar sea ice extent and thickness, which has led to changes in denning behavior. One such change in the southern Beaufort Sea (SBS) is that polar bears are selecting maternal den sites on land, rather than on unstable sea ice. This change, coupled with expanding petroleum exploration along Alaska's North Slope, heightens the likelihood of bear-human interactions at maternal den sites. The purpose of this research was to 1) describe polar bears' post-den emergence behavior, establishing a benchmark for comparison to identify behavioral changes associated with climate change and disturbance, and 2) explore factors influencing the efficacy of a currently used den detection method, forward-looking infrared (FLIR). Maternal den sites were observed along Alaska's North Slope from March to April of 2009 and 2010. The mean length of stay at den sites post-emergence was 11.3 ± 7.5 d. The mean date of den emergence was 14 March; abandonment 26 March. Adult females were generally inactive (58.4% out-of-den time) with standing being the most prevalent activity (49.9%). Cubs were generally active (76.7%), playing more than any other activity (45.3%). Bears spent the majority of their time in the den (97.3% for adult females and 99% for cubs) with short bouts of intermittent activity (× = 7 min 42 s). We documented the death of one member of a triplet polar bear litter at its den site. All three cubs showed low activity levels relative to other cubs observed, and one died within one week of den emergence. Necropsy confirmed that the dead cub had a low body weight and was malnourished. Capture later confirmed that the two surviving cubs were also undersized. Triplet litters are often smaller and suffer higher mortality rates than singletons and twins. This cub was not only a triplet but also born following 2 y of record minimum sea ice extent, both of which may have played a role in this cub's death. Concurrent with the den emergence portion of this work, we conducted a separate study to identify limitations and optimal conditions for locating dens using FLIR. We took handheld FLIR images of three artificial dens under varied conditions. We tested variables hypothesized to influence detectability with linear models using a zero-inflated negative binomial distribution. Solar radiation, wind speed, and den wall thickness reduced the likelihood of detecting dens. The negative effect of wind speed on detectability increased with increasing distance. To maximize the efficacy of hand-held FLIR, den surveys should be conducted when solar radiation is <16 w/m2 (night) and when wind speed is <10 km/h (6 mph). Adherence to these guidelines will maximize the protection FLIR can afford to denning bears.

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CNC machines are used with plenty of different implementations, one of which is in this project where a polar CNC machine was used to draw mesmerizing patterns on a table with fine sand. This construction read G-code and converted it to polar coordinates. The capabilities of what the plotter could draw were tested, everything from ODE plots to custom-made patterns and drawings with the help of Sandify. Although the patterns were drawn properly with small errors the ODE was too difficult to draw because it required a smaller magnetic ball and an even more precise system than what was used. This machine also generated noise at roughly 33 dB when it was in use. / CNC-maskiner används med massor av olika implementationer, en av dem är i det här projektet där en polar CNC maskin användes för att rita fascinerande mönster på ett bord fylld med fin sand. Denna konstruktion läste in G-kod och konverterade det till polära koordinater. Förmågan av vad maskinen kunde rita testades, allt från ODE grafer till specialtillverkade mönster och ritningar med hjälp av Sandify. Aven om de olika mönstren ritades ordentligt men med mindre små fel var ODE för svårt att rita på grund av att det krävde en mindre magnetisk kula och ännu mer noggrannhet jämfört med detta system. Denna maskin alstrade också ljud på cirka 33 dB under användning.