Ice cores are a valuable component with regards to paleoclimate reconstruction due to the ability to use stable water isotopic concentrations in ice as a proxy for paleo-temperature records. It is therefore important to understand the processes and conditions under which isotopic concentrations can be altered after ice has formed. Historically, sublimation has been considered to only have a trivial impact on the isotopic record in glacial ice due to the low diffusivity of solid ice (~10-15 m2 s-1). Recent publications have shown that diffusion of impurities through ice can occur at much faster rates than the diffusivity of solid ice would imply, and have proposed that networks of unfrozen liquid (premelt) between ice grains may expedite the diffusion process. However, the application of this mode of diffusion to isotopic concentrations in ice under non-equilibrium conditions has been largely unexplored. Here I model changes in isotopic concentrations in ice using a two-dimensional diffusion mechanism, which incorporates premelt, coupled with a sublimation flux at the surface. Model results show an increase in δD at the ice surface and in near-surface ice. Concentrations exponentially decrease from the surface value to the initial concentration at depth. These results are consistent with recent experimental results.

abstract: Dissolved organic matter (DOM) is an important part of aquatic foodwebs because it contains carbon, nitrogen, and other elements required by heterotrophic organisms. It has many sources that determine its molecular composition, nutrient content, and biological lability and in turn, influence whether it is retained and processed in the stream reach or exported downstream. I examined the composition of DOM from vascular wetland plants, filamentous algae, and riparian tree leaf litter in Sonoran Desert streams and its decomposition by stream microbes. I used a combination of field observations, in-situ experiments, and a manipulative laboratory incubation to test (1) how dominant primary producers influence DOM chemical composition and ecosystem metabolism at the reach scale and (2) how DOM composition and nitrogen (N) content control microbial decomposition and stream uptake of DOM. I found that differences in streamwater DOM composition between two distinct reaches of Sycamore Creek did not affect in-situ stream respiration and gross primary production rates. Stream sediment microbial respiration rates did not differ significantly when incubated in the laboratory with DOM from wetland plants, algae, and leaf litter, thus all sources were similarly labile. However, whole-stream uptake of DOM increased from leaf to algal to wetland plant leachate. Desert streams have the potential to process DOM from leaf, wetland, and algal sources, though algal and wetland DOM, due to their more labile composition, can be more readily retained and mineralized. / Dissertation/Thesis / Masters Thesis Biology 2018

This study focuses on trout fishing in the Great Smoky Mountains and the Blue Ridge Mountains from 1880 to 2017. I begin with a collection of personal narratives of fly-fishing in Tennessee to portray the allure of southern Appalachia trout fishing. I then describe the transition from native Cherokee fishing practices to sport fishing in the Smokies and the Blue Ridge by 1880. I explore a brief history of the National Parks and the United States Forest Service during the early 1900s, and address European fly-fishing influences in the United States during the twentieth century. I examine the habitats of the rainbow trout (oncorhynchus mykiss) and the native brook trout (salvelinus fontinalis) to provide an analysis on inter-species relationship between rainbow and brook trout in mountain streams. I then give an overview of important trout literature in the Smokies and the Blue Ridge through the twentieth and twenty-first centuries.

abstract: Monsoon hazards routinely affect the community, economy, and environment of the American Southwest. A common link for hazard development during the North American Monsoon concerns the interplay between temperature, moisture, and wind in the vertical atmosphere controlled by an unstable monsoon circulation. This dissertation investigates vertical atmospheric patterns using in-situ sounding data, specifically, 1) environments favorable for severe hail on the Colorado Plateau, 2) significant parameters distinguishing unhealthy versus healthy ozone days in Phoenix, Arizona, and 3) vertical profile alignments associated with distinct ranges in ozone concentrations observed in Phoenix having defined health impacts. The first study (published in the Journal of the Arizona-Nevada Academy of Science) determines significant variables on Flagstaff, Arizona 12Z rawinsonde data (1996-2009) found on severe hail days on the Colorado Plateau. Severe hail is related to greater sub-300 hectopascals (hPa) moisture, a warmer atmospheric column, lighter above surface wind speeds, more southerly to southeasterly oriented winds throughout the vertical (except at the 700 hPa pressure level), and higher geopotential heights. The second study (published in Atmospheric Environment) employs principal component, linear discriminant, and synoptic composite analyses using Phoenix, Arizona rawinsonde data (2006-2016) to identify common monsoon patterns affecting ozone accumulation in the Phoenix metropolitan area. Unhealthy ozone occurs with amplified high-pressure ridging over the Four Corners region, 500 hPa heights often exceeding 5910 meters, surface afternoon temperatures typically over 40°C, lighter wind speeds in the planetary boundary layer under four ms-1, and persistent light easterly flow between 700-500 hPa countering the daytime mountain-valley circulation. The final study (under revision in Weather and Forecasting) assesses composite atmospheric sounding analysis to forecast Air Quality Index ozone classifications of Good, Moderate, and collectively categories exceeding the U.S. EPA 2015 standard. The analysis, using Phoenix 12Z rawinsonde data (2006-2017), identifies the existence of “pollutant dispersion windows” for ozone accumulation and dispersal in Phoenix. Ultimately, monsoon hazards result from a complex and evolving vertical atmosphere. This dissertation demonstrates the viability using available in-situ vertical upper-air data to anticipate recurring atmospheric states contributing to specific hazards. These results will improve monsoon hazard prediction in an effort to protect public and infrastructure. / Dissertation/Thesis / Doctoral Dissertation Geography 2019

abstract: Understanding and predicting climate changes at the urban scale have been an important yet challenging problem in environmental engineering. The lack of reliable long-term observations at the urban scale makes it difficult to even assess past climate changes. Numerical modeling plays an important role in filling the gap of observation and predicting future changes. Numerical studies on the climatic effect of desert urbanization have focused on basic meteorological fields such as temperature and wind. For desert cities, urban expansion can lead to substantial changes in the local production of wind-blown dust, which have implications for air quality and public health. This study expands the existing framework of numerical simulation for desert urbanization to include the computation of dust generation related to urban land-use changes. This is accomplished by connecting a suite of numerical models, including a meso-scale meteorological model, a land-surface model, an urban canopy model, and a turbulence model, to produce the key parameters that control the surface fluxes of wind-blown dust. Those models generate the near-surface turbulence intensity, soil moisture, and land-surface properties, which are used to determine the dust fluxes from a set of laboratory-based empirical formulas. This framework is applied to a series of simulations for the desert city of Erbil across a period of rapid urbanization. The changes in surface dust fluxes associated with urbanization are quantified. An analysis of the model output further reveals the dependence of surface dust fluxes on local meteorological conditions. Future applications of the models to environmental prediction are discussed. / Dissertation/Thesis / Doctoral Dissertation Mechanical Engineering 2019

abstract: Human endeavors move 7x more volume of earth than the world’s rivers accelerating the removal of Earth’s soil surface. Measuring anthropogenic acceleration of soil erosion requires knowledge of natural rates through the study of 10Be, but same-watershed comparisons between anthropogenically-accelerated and natural erosion rates do not exist for urbanizing watersheds. Here I show that urban sprawl from 1989 to 2013 accelerated soil erosion between 1.3x and 15x above natural rates for different urbanizing watersheds in the metropolitan Phoenix region, Sonoran Desert, USA, and that statistical modeling a century of urban sprawl indicates an acceleration of only 2.7x for the Phoenix region. Based on studies of urbanization’s erosive effects, and studies comparing other land-use changes to natural erosion rates, we expected a greater degree of urban acceleration. Given that continued urban expansion will add a new city of a million every five days until 2050, given the potential importance of urban soils for absorbing anthropogenically-released carbon, and given the role of urban-sourced pollution, quantifying urbanization’s acceleration of natural erosion in other urban settings could reveal important regional patterns. For example, a comparison of urban watersheds to nearby non-urban watersheds suggests that the Phoenix case study is on the low-end of the urban acceleration factor. This new insight into the urban acceleration of soil erosion in metropolitan Phoenix can help reduce the acute risk of flooding for many rapidly urbanizing desert cities around the globe. To reduce this risk, properly engineered Flood Control Structures must account for sediment accumulation as well as flood waters. While the Phoenix area used regional data from non-urban, non-desert watersheds to generate sediment yield rates, this research presents a new analysis of empirical data for the Phoenix metropolitan region, where two regression models provide estimates of a more realistic sediment accumulation for arid regions and also urbanization of a desert cities. The new model can be used to predict the realistic sediment accumulation for helping provide data where few data exists in parts of arid Africa, southwest Asia, and India. / Dissertation/Thesis / Doctoral Dissertation Geography 2019

abstract: Atmospheric deposition of iron (Fe) can limit primary productivity and carbon dioxide uptake in some marine ecosystems. Recent modeling studies suggest that biomass burning aerosols may contribute a significant amount of soluble Fe to the surface ocean. Existing studies of burn-induced trace element mobilization have often collected both entrained soil particles along with material from biomass burning, making it difficult to determine the actual source of aerosolized trace metals. In order to better constrain the importance of biomass versus entrained soil as a source of trace metals in burn aerosols, small-scale burn experiments were conducted using soil-free foliage representative of a variety of fire-impacted ecosystems. The resulting burn aerosols were collected in two stages (PM > 2.5 μm and PM < 2.5 μm) on cellulose filters using a high-volume air sampler equipped with an all-Teflon impactor. Unburned foliage and burn aerosols were analyzed for Fe and other trace metals using inductively coupled plasma mass spectrometry (ICP-MS). Results of this analysis show that less than 2% of Fe in plant biomass is likely mobilized as atmospheric aerosols during biomass burning events. The results of this study and estimates of annual global wildfire area were used to estimate the impact of biomass burning aerosols on total atmospheric Fe flux to the ocean. I estimate that foliage-derived Fe contributes 114 ± 57 Gg annually. Prior studies, which implicitly include both biomass and soil-derived Fe, concluded that biomass burning contributes approximately 690 Gg of Fe. Together, these studies suggest that fire-entrained soil particles contribute 83% (576 Gg) of Fe in biomass burning emissions, while plant derived iron only accounts for at most 17%. / Dissertation/Thesis / Masters Thesis Chemistry 2019

Institutional and epistemological differences between science and management present a challenge to the implementation of sustainable environmental management. Environmental problems are complex and require at least multidisciplinary, but most effectively transdisciplinary approaches for learning, understanding, decision-making and problem solving. This means building bridges between institutional and epistemological differences. The role of system dynamics modelling in integrating environmental science and management is examined in this thesis. An action research methodology is adopted where, over cycles of case studies, the practical application of system dynamics modelling is evaluated. The role of system dynamics modelling in the management of coastal sand dunes, tourism, threatened species management and water management is explored in the case studies. It has been found that system dynamics modelling is a potentially powerful tool for integrating environmental science and management, principally assisting communication between scientists and management stakeholders. System dynamics group model-building, in particular, has the potential to facilitate stakeholder learning and assist stakeholders to think holistically about the complex systems they are trying to manage. It was also found that engaging stakeholders in system dynamics group model-building process is difficult. A model of factors influencing the adoption of system dynamics group model-building has been developed from this research. The model can be applied to assess the suitability of potential case studies and identify potential weaknesses that need to be addressed if the approach is to succeed.

No description available.

<p>The Convention on Biological Diversity (CBD) promotes the Ecosystem Approach (EA). In this thesis it is analyzed how the EA approach could be applied to regional management of coastal areas in Sweden. The aim of this report is to compare management for preserving biodiversity on a landscape level in two regional coastal areas in Uppsala and Västra Götaland respectively. In Uppsala, one of the plans consists of a previous nature reserve and in Västra Götaland, a Regional landscape strategy has been established. The ecosystem approach is used as a theoretical framework in this thesis. More precisely, five EA operational guidelines have been used as analytical tools in the comparative approach adopted.</p><p>The results show that the Västra Götaland Regional landscape strategy has been most consistent with the EA framework, since it fulfills three of the five operational guidelines while Gårdsskärskusten only accomplish two of the criteria. The social aspects are more central in the landscape strategy than in Gårdskärskusten, which is the main difference between the two plans. One area of inadequacy detected in the landscape strategy was the few identified aspects on maintenance of landscape connectivity features. The Regional landscape strategy could, if established in every county in Sweden, be a way to prevent the loss of biodiversity. However the plan needs to be supported by actions where preservation and utilization are integrated in an economic context. By considering nature protection as a development opportunity in strategic planning rather than as only a cost, important steps towards a sustainable future can be taken.</p> / <p>För att implementera målsättningarna i FN:s Konvention om Biologisk Mångfald har en ekosystemansats (EA) antagits och en viktig ekosystemtyp i Sverige där EA kan appliceras är kuster. Syftet med examensarbetet är att, med ekosystemansatsen som analysverktyg, studera hur och varför två planer för att bevara biologisk mångfald på landskapsnivå i två regionala kustområden i Uppsala län respektive Västra Götalands län skiljer sig åt. Planen består i Uppsala län av ett tilltänkt naturreservat och i Västra Götalands län av en Regional landskapsstrategi. Uppsatsens teoretiska förankring sker i ekosystemansatsen, med fokus på dess fem vägledande punkter och metodvalet är en jämförande design. Inom ramen för den jämförande designen har sedan en innehållsanalys samt kompletterande semistrukturerade intervjuer utförts.</p><p>Resultatet visar att den Regionala landskapsstrategin i dagsläget är mer i linje med ekosystemansatsen, eftersom den uppfyller tre av fem vägledande punkter medan processen med Gårdsskärskusten enbart uppfyller två av fem vägledande punkter. I landskapsstrategin är sociala aspekter centrala och det är en förklaring till varför de olika planerna skiljer sig åt. Intressant är dock att betoningen på aktörsinvolvering verkar leda till att vissa ekologiska grundprinciper som konnektivitet i landskapet tonas ned, vilka är framträdande i processen med Gårdskärskusten. Regionala landskapsstrategier kan enligt min mening innebära ett stort steg mot att hindra förlusten av biologisk mångfald i Sverige om de uppförs i varje län. Inom landskapsstrategierna är det vidare essentiellt att skyddade områden, som exempelvis Gårdsskärskusten, också inkorporerar ett landskapsstrategitänk och i många fall innebär det att skötselåtgärder fortsätter att utföras. Svårigheten kan dock vara hur finansieringen av skötseln skall ske men där finns alternativa inkomstmöjligheter, från exempelvis naturturism och stresshantering på företag, som behöver utvecklas ytterligare.</p>