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Wind erosion, transport and deposition of particulate matter can have significant impacts on the environment. It is observed that about 40% of the global land area and 30% of the earth's population lives in semiarid environments which are especially susceptible to wind erosion and airborne transport of contaminants. With the increased desertification caused by land use changes, anthropogenic activities and projected climate change impacts windblown dust will likely become more significant. An important anthropogenic source of windblown dust in this region is associated with mining operations including tailings impoundments. Tailings are especially susceptible to erosion due to their fine grain composition, lack of vegetative coverage and high height compared to the surrounding topography. This study is focused on emissions, dispersion and deposition of windblown dust from the Iron King mine tailings in Dewey-Humboldt, Arizona, a Superfund site. The tailings impoundment is heavily contaminated with lead and arsenic and is located directly adjacent to the town of Dewey-Humboldt. The study includes in situ field measurements, computational fluid dynamic modeling and the development of a windblown dust deposition forecasting model that predicts deposition patterns of dust originating from the tailings impoundment. Two instrumented eddy flux towers were setup on the tailings impoundment to monitor the aeolian and meteorological conditions. The in situ observations were used in conjunction with a computational fluid dynamic (CFD) model to simulate the transport of windblown dust from the mine tailings to the surrounding region. The CFD model simulations include gaseous plume dispersion to simulate the transport of the fine aerosols, while individual particle transport was used to track the trajectories of larger particles and to monitor their deposition locations. The CFD simulations were used to estimate deposition of tailings dust and identify topographic mechanisms that influence deposition. Simulation results indicated that particles preferentially deposit in regions of topographic upslope. In addition, turbulent wind fields enhanced deposition in the wake region downwind of the tailings. This study also describes a deposition forecasting model (DFM) that can be used to forecast the transport and deposition of windblown dust originating from a mine tailings impoundment. The DFM uses in situ observations from the tailings and theoretical simulations of aerosol transport to parameterize the model. The model was verified through the use of inverted-disc deposition samplers. The deposition forecasting model was initialized using data from an operational Weather Research and Forecasting (WRF) model and the forecast deposition patterns were compared to the inverted-disc samples through gravimetric, chemical composition and lead isotopic analysis. The DFM was verified over several month-long observing periods by comparing transects of arsenic and lead tracers measured by the samplers to the DFM PM₂₇ forecast. Results from the sampling periods indicated that the DFM was able to accurately capture the regional deposition patterns of the tailings dust up to 1 km. Lead isotopes were used for source apportionment and showed spatial patterns consistent with the DFM and the observed weather conditions. By providing reasonably accurate estimates of contaminant deposition rates, the DFM can improve the assessment of human health impacts caused by windblown dust from the Iron King tailings impoundment.

Windblown dust events can be defined as windblown dust emitted from the Earth's surface to the atmosphere. These events have significant impact on local air quality. Predicting the location and magnitude of these events is vital for Utah air quality assessment and planning. Previous modeling studies have focused only on past dust events. This work utilized a state-of-the-science software framework based on the Community Multiscale Air Quality (CMAQ) v5.3.1 modeling system to predict dust events in Utah. The framework was verified using previous studies for dust events in April 2017 and March 2010. Once verified, the framework was used to predict the impact of future land use properties on dust events. Two scenarios were studied – shrinking of the Great Salt Lake and the addition of large-scale solar farms west of the Wasatch Front. Both showed increases in dust concentrations overpopulated areas using the meteorological conditions from the April 2017 dust event. Such information from future impact studies can assess potential impacts from climate change and can guide government water and land use policies to mitigate dust event impacts.

Magistro darbe tiriama 2010 m. rugpjūčio mėnesį Dubravos EMMU audros pažeisti medynai ir juose pagaminta apvaliosios medienos kokybė. Darbo objektas – 2010 m. rugpjūčio mėnesį škvalo Dubravos EMMU pažeisti medynai. Medienos kokybės bei medžių stiebų sortimentinės struktūros tyrimai atliekami Dubravos EMMU, Vaišvydavos girininkijoje esančiame škvalo pažeistame brandžiame eglyne. Darbo tikslas – Įvertinti vėjavartų apimtį ir medienos kokybės pokyčius Dubravos EMMU. Darbo metodai – Darbe naudoti dokumentų analizės, duomenų grupavimo, palyginimo, vidurkių skaičiavimo ir apibendrinimo metodai. Darbo rezultatai. Išanalizavus Dubravos EMMU audros likvidavimo metu 2010 m. 10-12 mėn. pagamintų pjautinųjų sortimentų kiekius nustatėme, kad pagaminta 76% daugiau negu visada, prastesnės C klasės medienos. Dubravos EMMU, Šilėnų ir Vaišvydavos girininkijose įvertinus vėjo pažeidimus pagal plotą skirtingose augavietėse 60 brandžių medynų, nustatėme, kad intensyviausiai pažeisti medynai, kurie sudaro 35% yra Lcp augavietėse. Įvertinus pažeistus medynus pagal vyraujančią medžių rūšį nustatyta, kad didžiausią pažeistų medynų dalį 46.9% sudaro eglynai. Sortimentuojant 26 vėjo pažeistus medžius nustatyta, kad dėl pakitusios sortimentinės struktūros dėl lūžių taškuose suskeldėjusios medienos, prarandama iš viso 19.8% likvidinės medienos, bei vidutiniškai vieno medžio kirtimo atliekų kiekis padidėja 2.1 karto. Iš vėjo pažeistų medžių, pjautinųjų sortimentų medienos kokybė lyginant su galimai... [toliau žr. visą tekstą] / Study object – 2010.08.08 storm damaged forest stand at Dubrava forest enterprise. Windblown timber quality assessment and storm damaged tree round wood structure assessment was done at Vaišvydava local forest district, at Dubrava forest enterprise. Study aim - to quantify most damaged forest types and to assess the round wood quality losses due to stem breakage and other defects which reduced merchantable timber volume during logging at damaged stands, after 2010.08.08 storm at Dubrava forest enterprise. Methodology – Data grouping, comparison, generalization, document’s analysis. Results - As the main changes in round wood quality during the period of salvage clear cuttings of storm damaged timber at Norway spruce stands at DFE were seen a significant increase of C quality class Norway spruce (Picea abies L) sawn logs – 76 per cent of all sawn logs. Evaluation of windthrow damage on DFE results showed that nearly half (46.9 percent) of all damages occurred on Norway spruce stands. As the most endangered forest soil type of spruce stands, where one third of all damages occurred, was recorded: fertile and humid Myrtillo-oxalidosum site. Survey of 26 storm damaged trees round wood structure showed, that 19.8% reduction of merchantable volume is due to breakage, and due to that fact was seen significant increase - 2.1 time amount of residuals. Windblown tree round wood quality assessment showed significant difference in timber quality if we compare it with normal conditions... [to full text]

Ce mémoire présente une étude spectroscopique de la nébuleuse Wolf-Rayet (WR) NGC 2359 à l’aide d’un ensemble de données recueillies avec le spectromètre imageur SITELLE et le spectromètre GMOS depuis 2018. Cette étude vise à approfondir nos connaissances sur cette nébuleuse ionisée par une étoile massive au stade final de sa vie, WR7, afin de localiser et de caractériser la section de la nébuleuse associée aux éjecta passés de l’étoile. L’analyse de l’ensemble de données permet d’identifier dans un premier temps les raies d’émission de plusieurs atomes à des états d’ionisation différents et dans un deuxième temps d’identifier les zones où ces raies sont les plus fortes à l’aide de la production de cartes de flux pour chacune d’entre elles. Deux structures sont associées au gaz ionisé de la nébuleuse. La première est en forme d’arc et est à la frontière à l’est de WR7 qui sépare le gaz ionisé du gaz atomique. La deuxième est une bulle filamenteuse qui a un état d’ionisation plus élevé que celui de l’arc par son flux très faible dans les raies d’émission d’atomes simplement ionisés, mais fort dans les raies d’atomes doublement ionisés. L’analyse cinématique vient ajouter des distinctions supplémentaires entre les deux structures. L’arc est immobile à 54 km s⁻¹ qui est la vitesse radiale systémique du gaz attendue à sa distance galactocentrique. La bulle démontre plutôt des groupes de filaments qui s’approchent de l’observateur et d’autres qui s’en éloignent, donnant une expansion de ∼ 30 km s⁻¹. De plus, ces résultats confirment le contact dynamique entre le gaz ionisé en expansion et le gaz moléculaire de CO allant à des vitesses similaires à des positions similaires. Ensuite, certains rapports d’intensité de raies sensibles à la présence de poussière, à la température électronique ou à la densité électronique permettent de cartographier ces propriétés. La poussière causant un rougissement interstellaire est surtout distribuée à l’est et au sud de la nébuleuse. La densité électronique est maximalement de 190 cm⁻³ et généralement inférieure à 100 cm⁻³. En supposant une densité électronique constante de 100 cm⁻³, la carte de la température électronique montre des valeurs entre 9 000 et 14 000 K. / This work presents a spectroscopic study of the Wolf-Rayet (WR) nebula NGC 2359 using a set of data collected with the SITELLE imaging spectrograph and the GMOS spectrograph since 2018. The study aims to deepen our understanding of this nebula ionized by a massive star in the final stage of its life, in order to determine which gas structure of the nebula is associated with the past ejecta of the star. The analysis of the data set first identified emission lines of several atoms in different ionization states, and then identified the areas where these lines are strongest by producing flux maps for each of the identified lines. Two structures are associated with the ionized gas of the nebula. The first is arc-shaped and is at the western boundary separating the ionized gas from the atomic gas. The second is a filamentary bubble with a higher ionization state than the arc due to its very weak flux in the emission lines of singly ionized atoms, but strong in the lines of doubly ionized atoms. The kinematic analysis adds further distinctions between the arc and the bubble. The arc is stationary at 54 km s⁻¹ , which is the systemic radial velocity of the gas expected at its galactocentric distance. The bubble shows groups of filaments approaching and receding from the observer, demonstrating an expansion at 30 km s⁻¹. These results confirm the dynamic contact between the expanding ionized gas and the CO molecular gas moving at similar speeds in similar locations. Furthermore, some intensity ratios of lines sensitive to the presence of dust, electron temperature, and electron density allow for mapping these quantities. Dust causing interstellar reddening is mainly distributed to the east and south of the nebula. The electron density is maximally 190 cm⁻³ and generally below 100 cm⁻³. Assuming a constant electron density of 100 cm⁻³, an electron temperature map ranges between 9,000 K and 14,000 K.