Now showing items 135-154 of 1029

• #### Characterization And Interpretation Of Volcanic Activity At Redoubt, Bezymianny And Karymsky Volcanoes Through Direct And Remote Measurements Of Volcanic Emissions

Surface measurements of volcanic emissions can provide critical insight into subsurface processes at active volcanoes such as the influx or ascent of magma, changes in conduit permeability, and relative eruption size. In this dissertation I employ direct and remote measurements of volcanic emissions to characterize activity and elucidate subsurface processes at three active volcanoes around the North Pacific. The 2009 eruption of Redoubt Volcano, Alaska, produced elevated SO2 emissions that were detected by the Ozone Monitoring Instrument (OMI) satellite sensor for over three months. This provided a rare opportunity to characterize Redoubt's daily SO2 emissions and to validate the OMI measurements. Order of magnitude variations in daily SO2 mass were observed, with over half of the cumulative SO2 emissions released during the explosive phase of the eruption. Correlations among OMI daily SO2 mass, tephra mass and acoustic energies during the explosive phase suggest that OMI data may be used to infer eruption size and explosivity. From 2007 through 2010 direct and remote measurements of volcanic gas composition and flux were measured at Bezymianny Volcano, Kamchatka, Russia. During this period Bezymianny underwent five explosive eruptions. Estimates of passive and eruptive SO2 emissions suggest that the majority of SO2 is released passively. Order of magnitude variations in total volatile flux observed throughout the study period were attributed to changes in the depth of gas exsolution and separation from the melt at the time of sample collection. These findings suggest that exsolved gas composition may be used to detect magma ascent prior to eruption at Bezymianny Volcano. Karymsky Volcano, Kamchatka, Russia, is a dynamic volcano which exhibited four end-member activity types during field campaigns in 2011 and 2012, including: discrete ash explosions, pulsatory degassing, gas jetting, and explosive eruption. These activity types were characterized quantitatively and uniquely distinguished using a multiparameter dataset based on infrasound, thermal imagery, and volcanic emissions. These observations suggest a decoupling between exsolved volatiles and magma at depth. I propose that variations in magma degassing depth influence the flux and proportions of decompression- and crystallization-induced degassing, as well as conduit permeability, can explain the variations in volcanic activity.
• #### Characterization of host-pathogen interactions in two model pathogens: Francisella tularensis and simian virus SV40

We sought to elucidate the molecular mechanisms of host-pathogen interaction. The bacterium Francisella tularensis and simian virus SV40 represent two ideal model systems. Francisella tularensis is a facultative intracellular bacterium known to dampen the host immune response to infection. The Francisella pathogenicity island (FPI) encodes a cluster of 19 genes essential for full virulence and the observed change in immune response. We investigated the role of two FPI encoded proteins, PdpC and PdpD, on immune response. While both proteins affect a change, the effect of PdpD is more pronounced, and appears to play a role in modulation of host immune responses. SV40 is a DNA polyoma virus that targets GM1 receptors for entry into cells. The GM I receptor is localized to cholesterol-rich membrane microdomains, termed lipid rafts. Disruption of lipid rafts using the cholesterol chelator methyl-P-cyclodextrin prevents SV40 entry into cells. We investigated whether natural product alternatives would similarly disrupt lipid raft integrity and prevent viral entry. The triterpenoid ursolic acid, present in many plants, has been shown to possess antimicrobial properties and was used to treat cells prior to infection with SV40. We found ursolic acid to have no effect on the viral infectivity of SV40.
• #### Characterization Of Permafrost Development By Isotopic And Chemical Analysis Of Soil Cores Taken From The Copper River Basin And An Upland Loess Deposit In Interior Alaska

Chemical and isotopic analyses of pore water from permafrost cores taken from the dry lake bed of ancient Lake Atna in the Copper River Basin and from an upland loess deposit northeast of Fairbanks, Alaska reveal information about the local past environments not available by other means. Thawed core samples from both sites were analyzed for delta18O and deltaD values using an isotope ratio mass spectrometer. Water content was determined as well, and subsamples of the cores were analyzed for nitrogen and carbon content. Water extracts of the core samples were analyzed for cations (Ca, Mg, K and Fe), as well as pH, electrical conductivity, and bicarbonate. Magnetic susceptibility was determined on samples from the Fairbanks site. Data from samples taken from the Lake Atna site revealed a sequence of events that occurred in the basin after the lake drained about 10,000 years ago. At one location, oxygen isotopes show that permafrost formed continuously down through the lakebed. At the other location, 400 m distant, oxygen isotopes show that after permafrost formed, a thaw lake was produced on top of the permafrost. After the thaw lake had drained at least one wildfire passed through the area, large enough to thaw the surface permafrost to a depth of over 2 m at both core sites. The surface permafrost refroze, and currently the permafrost at the research site extends from 1 m depth to between 45 and 55 m depth. At the Fairbanks site chemical analyses showed indications of pedogenesis at several depths in the loess profile of the permafrost core. Water isotope data from a site where the permafrost table is at less than 1 m depth show repeated episodes of thawing and refreezing. Charcoal and ash in several layers of soil in the area and from the sample core suggest that fire may be the cause for the thawing events. The primary core water isotope analyses also show several thawing and refreezing events, but the depths of the signatures in the core indicate that these episodes happened thousands of years ago when the ground surface was much lower than it is today.
• #### Characterization of the adenosine A1 receptor in summer and winter Arctic ground squirrels

Hibernation is an adaptation that allows the Arctic ground squirrel (Urocitellus parryii) to survive the harsh arctic winter. Recently the activation of the Adenosine A1 receptor (A₁AR) has been shown to be necessary for entrance into hibernation during the winter but not summer season. In the current study we characterize the A₁AR in the forebrain, hippocampus and hypothalamus of summer and winter AGS. We also tested the hypothesis that increased A₁AR agonist efficacy is responsible for increased sensitization of the A₁AR during the winter season. The resulting ³⁵S-GTPγS binding data indicated an increase in agonist potency during the winter season in all three brain regions. A plausible explanation of our results is that increased potency in the forebrain during the winter season is due to an increase in efficacy as indicated by a greater number of receptors in the high affinity state. In addition ³⁵S-GTPγS binding, [³H] DPCPX saturation and competition assays establish for the first time pharmacological characteristics such as EC⁵⁰, Kd, Kilo and Kihi in AGS brain.
• #### Characterization Of The Dat Zone, Eastern Alaska Range, Alaska: A Calcic Iron (Copper-Gold) Skarn Prospect

I studied a Cu-Fe-Au prospect in the eastern Alaska Range, Alaska, informally known as 'the DAT Zone'. Previous workers disagreed about the prospect's genesis; my work conclusively shows it to be a calcic iron skarn deposit with late quartz-pyrite-gold mineralization, broadly coeval with the host Pennsylvanian island arc-related volcanic and associated sedimentary rocks. A sericite-quartz-pyrite altered shear yields a $\sp{40}$Ar/$\sp{39}$Ar age similar to that of a nearby quartz monzodiorite pluton (300 Ma $\pm$ 1 Ma). The skarn consists of andradite extensively retrograded to ferrotremolite, quartz, magnetite, hematite, calcite, and chalcopyrite. Based on alteration pseudomorphs, the prograde assemblage was clinopyroxene with 20-40 %Hd, wollastonite, and andradite. The main-stage fluids were approximately 600$\sp\circ$C, moderately oxidized, and extremely saline ($>$60% NaCl equivalent). This fluid was clearly different from those of volcanogenic massive sulfide, metamorphic, or epithermal deposits. The lack of explosive textures is inconsistent with the DAT Zone as a porphyry copper deposit. <p>

• #### Characterizing the Afghanistan aerosol environment using size- and time- resolved aerosol chemical composition measurements

The exposure to aerosols is one danger U.S. soldiers face in Afghanistan that may go unseen. Using the Davis Rotating-drum Universal-size-cut Monitoring (DRUM) cascade impactor, size- and time- resolved aerosol chemical concentrations from Bagram, Afghanistan were collected. These aerosol concentrations were combined with a meteorological analysis and Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model meteorological backward trajectories to establish source sectors. These sectors, along with time of year, were then used as a predictive tool for the chemical composition and relative concentration of aerosols in Afghanistan. Principal components analysis (PCA) was used to determined potential source types. PM₁₀ and PM₂.₅ were compared to military exposure guidelines and U.S. national ambient air quality standards. Results reveal aerosol concentrations in Afghanistan were at levels for which adverse health effects could be anticipated.
• #### Characterizing wintertime aerosol composition and sulfate formation in Fairbanks, Alaska

The citizens of Fairbanks, Alaska are exposed to high levels of air pollutants throughout the winter months, causing the city to violate the Fine Particulate Matter (PM₂.₅) National Ambient Air Quality Standards set in place by the United States Environmental Protection Agency. Previous studies have shown the significant amount of sulfate aerosols particles observed in Fairbanks winters, but the formation mechanism of aerosols containing sulfate in the atmosphere is still unknown. While sulfate aerosol particle formation is commonly driven by oxidants including ·OH, H₂O₂ and O₃, these photochemical species are limited in Fairbanks winter months. This indicates sulfate aerosol particle formation may occur through a nontraditional pathway, and this project investigates one proposed mechanism in which transition metals may catalyze sulfate aerosol particle formation. We collected twelve full diurnal cycles over the winter months of 2019, using a particle-to-liquid sampler (PILS) at hourly time resolution. This PILS instrument creates an aqueous extract containing only the water-soluble components of the aerosol particles. These aqueous extracts were analyzed offline for inorganic and metal concentrations by ion chromatography (IC) and inductively coupled plasma mass spectrometry (ICP-MS). This hourly dataset provides new insights in emissions, chemical processing and their coupling with boundary layer dynamics. We find a strong correlation between hourly sulfate and PM2.5 mass concentrations, but we do not find the strong evidence of transition metal ion (TMI) catalysis on sulfate formation. We also collected twelve sets of aerosol filters using Micro-Orifice Uniform Deposit Impactor (MOUDI) throughout the winter of 2019. These size-resolved filter samples suggest the presence of hydroxymethane sulfonate (HMS) in submicron particles when temperatures are below -30 °C (-22 °F), suggesting a new reservoir for sulfur compounds in Fairbanks winter and warranting further investigation.
• #### Chemical and mass spectral studies of 2,2-dialkylglycine decarboxylase

2,2-Dialkylglycine Decarboxylase, DGD, is a decarboxylating transaminase that is dependent on a vitamin B6 cofactor, pyridoxal 5'-phosphate (PLP). DGD catalyzes the decomposition of 2-methylalanine in two steps. DGD was purified by ammonium sulfate precipitation and ion-exchange chromatography. The enzyme was reduced to form a covalent bond between the enzyme and the PLP. Also, [alpha]-(Trifluoromethyl) Alanine, a suicide mechanism based inhibitor was reacted with DGD until the enzyme was completely inactivated. The nonmodified DGD and these two modified forms of the enzyme were subjected to enzymatic digestion by trypsin. Finally, all three peptide mixtures were analyzed by LC/MS/MS. The mass spectra confirmed the amino acid sequence as predicted by the nucleotides of the gene, and the covalent attachment of the cofactor to lysine 272.
• #### Chemical Composition Of Ice Surfaces: Implications For Springtime Bromine Chemistry

Reactive bromine chemistry is responsible for events of almost total tropospheric O3 destruction and the deposition of mercury during the Arctic spring. The source of the majority of the atmospheric bromine loading is salts from seawater, but many questions remain on the mechanism by which salts are transported and chemically activated to reactive species. Specifically, the role of snow and ice surfaces in exchanging bromine with the atmosphere needed investigation. Therefore, we undertook a detailed study of the ionic composition of selected ice surfaces near Barrow, Alaska and tracked modifications with respect to Cl- and Na+ (sea-salt tracers) in approximately 1,400 samples. We developed data analysis tools to observe modifications and related these methods to the traditional enrichment factor and the non-sea-salt abundance methods. Surface snow was highly modified in Br- composition by atmospheric exchanges that both add and remove bromine, providing evidence for snow's involvement in reactive bromine chemistry. Calcium was enriched by dust input. Sulfate in surface snow was fractionated at the source by mirabilite (Na2SO 4 &bull; 6H2O) precipitation and enriched by Arctic haze inputs. Frost flowers are vapor-grown ice crystals that wick brine and may be involved in sea-salt aerosol production and production of reactive halogen species. Detailed examination of frost flower growth and chemical composition shows that they are sites of mirabilite precipitation and separation, which can lead to sulfate-depleted aerosol particles, but show no sign of direct reactive bromine production. By simultaneously studying snow, ice, aerosol particles, and gas-phase bromine species, we made a mass balance of bromine in various reservoirs. This mass balance points away from frost flowers and towards snow as the dominant source of reactive bromine. This work develops a mechanistic picture of how reactive bromine chemistry depends upon snow and sea ice that is needed to make meaningful predictions of how the recent changes to the Arctic sea ice cover will affect air pollution chemistry.
• #### Chemical variations in the waters draining the Hi-Yu Mine

There are two sources of contamination from the Hi-Yu mine: the 'mill seep' and the mine tailings. The mill seep has an acid pH (4.8) containing 20 parts per billion (ppb) Cd and 2400 ppb Zn. Water draining the mine tailings contains 300 ppb As and 30 ppb Sb. These concentrations are above the EPA and State of Alaska Maximum Contaminant Levels (MCL). Once the mill seep mixes with Moose Creek, the pH increases, leading to the precipitation of iron and manganese hydroxides with associated As, Cd, Sb, and Zn. Samples of the iron precipitate contain> 10,000 parts per million (ppm) As, 20 ppm Cd, 240 ppm Sb, and 2600 ppm Zn. Precipitation of metals, along with interaction of organic material and dilution, lowers metal contaminant levels below MCL levels within 0.8 km of the mixing point. Although technically a point source of pollution, the seep and tailings cause no significant increase in the metal content of Fairbanks Creek, 1.2 km downstream of the Hi- Yu mine. The mixing and dilution of waters, adsorption of metals onto Fe and Mn oxy-hydroxide phases, and the settling of particles make the discharge relatively benign, despite the unsightly iron hydroxide precipitate locally present.
• #### Chronologic multisensor assessment for Mount Cleveland, Alaska from 2000 to 2004 focusing on the 2001 eruption

The hazard posed by Mount Cleveland in Alaska's central Aleutian Islands is the interaction between erupted ash and aircraft. The understanding of these potential hazards can be applied to other threatening volcanoes in the Aleutian Islands. Remote sensing satellites have been useful for constraining the chronological events of the 2001 eruption activity. Thermal infrared data is analyzed for maximum estimated thermal flux of 15.3 GW and maximum effusion rates of 4.6 m³/s during the February 19, 2001 eruption. These thermal estimates are compared to known field observations of the deposits to better classify the eruption sequence and activity. This sequence on the western flank of volcaniclastic debris-lahar-lava is similar to the stratigraphy of past deposits nearby. Post-eruption analysis of satellite and field observation data provide a useful view into the erosion of a 1.2 x 10⁶ m³ volcaniclastic debris flow fan deposit from the eruption along with continued morphologic changes of the volcano. Areal analysis of the fan deposit in radar imagery from March 31, 2001 until December 21, 2003 indicates an average decreasing trend of 20 m²/day. This unique chance to determine the erosion rate of this deposit may be applied to similar eruption deposits at other island volcanoes.

• #### Climate (temperature & humidity) data logger data from EasyLogUSB in interior Alaska

These data are daily climate data (temperature and humidity) collected on transects in interior Alaska throughout the year. Data were collected for the years 2015, 2016 and 2017 by ski, with dogs, by bike and by car. An attached EasyLogUSB data logger was used and usually 10 second interval records were collected during a 1hour data session, or more (daily profiles, some are stationary for 24hours). Temperature is collected as degrees Celsius and humidity as percent; data exist as a txt/ASCII format in columns. These data are referenced to time and locations, and they can be used as cross-profiles for landscape climate and ground-truthing of climate models using GIS and geo-referencing. Data include the �sampling of altitudinal profiles, landscape cover, river crossings and various topographies, including coastal-interior gradients. Data collection is still ongoing.
• #### Climate and predictability of Alaska wildfires

Wildfires burn an average of 3,760km² each year in Alaska, but varies greatly from year to year. These fires, started by human and natural causes, can endanger life and property when they approach populated areas. The relationship between seasonal area burned and monthly and seasonal average mean sea level pressure, surface air temperature, total column precipitable water, 500hPa and 700hPa geopotential height, 700hPa specific humidity and 1000-500hPa layer thickness is examined. The assessment was done by examining the spring and summer seasonal composites associated with extreme high and low seasons. This showed the predominant anomalies from the climatology for seasons of both extremes. Point correlations were also made between seasonal area burned and the aforementioned climate variables for the entire Northern Hemisphere. Points of particularly high correlation with area burned were used in multiple regressions for both spring and summer, and for the preseason only to predict seasonal area burned. Results show correlations of about 0.78 for the preseason regression and 0.91 for the total period. The seasonal area burned in Alaska is intimately linked with the ongoing synoptic situation on monthly and seasonal scales before and during the fire season.
• #### Climate drivers of Interior Alaska wildland fire

This study focused on the climate drivers of wildfire in Interior Alaska that occurred in summer season, JJA, during periods in 1994 to 2017. Analysis results presented in this paper provide identify links between meteorological variables and area burned, in the context of spatial and temporal variability at the PSA level. Warmer temperatures caused higher chance of wildland fires as in summer 2004 (26797 km2) where the temperature reached the highest levels compared to all years of study. In addition, this study has shown that temperatures have the same seasonal cycle in all PSAs level; where the temperature increase begins in June, peaks in July and then gradually decline, consistent with the fire season. Although precipitation limits the increase in forest fires, the accompanying lightning increases the chance fires which gives precipitation a double role in influencing the risk of fire. This can be seen clearly in both Upper Yukon valley (AK02) and Tanana Zone South (AK03S) where the largest number of lightning strikes over Interior Alaska occur (17000 and 11000 strikes, respectively). In addition, these two PSAs have the greatest area burned (1441.2 and 1112.4 km2).There is an upward trend in both temperature and precipitation in all months especially in May and September which indicates a decline in the snow season and an increase in the length of the fire season. A similar pattern was documented between PSAs in eastern versus western Alaska. Eastern PSAs receive the highest amount of precipitation in July, (AK01W , AK01E, AK02, AK03N, AK03S) , and western PSAs in August, (AK04, AK05, AK07). The years 2004, 2015, 2005 and 2009 display the largest values for area burned with extremely warm and dry condition especially in 2004 with approximately 26797 km2 (6.6 m acres).
• #### Climate, seasonal snow cover and permafrost temperatures in Alaska north of the Brooks Range

Climatological data, active layer and permafrost measurements, and modeling were used to investigate the response of permafrost temperatures to changes in climate in Alaska north of the Brooks Range. Mean annual air temperature (MAAT) from 1987 to 1991 within about 110 km from the Arctic Coast was ${-12.4}\pm0.3\sp\circ C,$ while the mean annual permafrost surface temperature (MAPST) ranged from ${-9.0}\sp\circ C$ along the coast to ${-5.2}\sp\circ C$ inland. Air temperature changes alone can not explain the permafrost warming from the coast to inland. Measurements show that MAPST are about $3\sp\circ C$ to $6\sp\circ C$ warmer than MAAT in the region. The interaction of local microrelief and vegetation with snow appears to change the insulating effect of seasonal snow cover and may be the major factor which controls the permafrost temperature during the winter and thus the MAPST. Sensitivity analyses show that for the same MAAT conditions, changes in seasonal snow cover parameters can increase or decrease the MAPST about $7\sp\circ C.$ Snowfall was greater during the cold years and less during the warm years and was poorly correlated between stations. These results suggest that the effects of changes in air temperatures on permafrost temperatures historically may also have been modified by changes in snow cover. A numerical model was used to investigate the effect of changes in initial permafrost temperature conditions, MAAT, seasonal snow cover and thermal properties of soils on the permafrost temperatures. Permafrost may have started warming about the same time as the atmosphere did in the late 1800's, and the long term mean surface temperature of the permafrost may have been established prior to this time. Variations in the penetration depth of the warming signal may be related to differences in thermal properties of permafrost. Variations in the magnitude of the permafrost surface warming may be due to the effect of local factors such as soil type, vegetation, microrelief, soil moisture, and seasonal snow cover. The effect of the interaction of vegetation and snow cover may amplify the signal of temperature change in the permafrost.
• #### Climate-induced changes in ecological dynamics of the Alaskan boreal forest: a study of fire-permafrost interactions

A warming climate is expected to cause widespread thawing of discontinuous permafrost, and the co-occurrence of wildfire may function to exacerbate this process. Here, I examined the vulnerability of permafrost to degradation from fire disturbance as it varies across different landscapes of the Interior Alaskan boreal forest using a combination of observational, modeling, and remote sensing approaches. Across all landscapes, the severity of burning strongly influenced both post-fire vegetation and permafrost degradation. The thickness of the remaining surface organic layer was a key control on permafrost degradation because its low thermal conductivity limits ground heat flux. Thus, variation in burn severity controlled the local distribution of near-surface permafrost. Mineral soil texture and permafrost ice content interacted with climate to influence the response of permafrost to fire. Permafrost was vulnerable to deep thawing after fire in coarse-textured or rocky soils throughout the region; low ice content likely enabled this rapid thawing. After thawing, increased drainage in coarse-textured soils caused reductions in surface soil moisture, which contributed to warmer soil temperatures. By contrast, permafrost in fine-textured soils was resilient to fire disturbance in the silty uplands of the Yukon Flats ecoregion, but was highly vulnerable to thawing in the silty lowlands of the Tanana Flats. The resilience of silty upland permafrost was attributed to higher water content of the active layer and the associated high latent heat content of the ice-rich permafrost, coupled with a relatively cold continental climate and sloping topography that removes surface water. In the Tanana Flats, permafrost in silty lowlands thawed after fire despite high water and ice content of soils. This thawing was associated with significant ground surface subsidence, which resulted in water impoundment on the flat terrain, generating a positive feedback to permafrost degradation and wetland expansion. The response of permafrost to fire, and its ecological effects, thus varied spatially due to complex interactions between climate, topography, vegetation, burn severity, soil properties, and hydrology. The sensitivity of permafrost to fire disturbance has also changed over time due to variation in weather at multi-year to multi-decadal time scales. Simulations of soil thermal dynamics showed that increased air temperature, increased snow accumulation, and their interactive effects, have since the 1970s caused permafrost to become more vulnerable to talik formation and deep thawing from fire disturbance. Wildfire coupled with climate change has become an important driver of permafrost loss and ecological change in the northern boreal forest. With continued climate warming, we expect fire disturbance to accelerate permafrost thawing and reduce the likelihood of permafrost recovery. This regime shift is likely to have strong effects on a suite of ecological characteristics of the boreal forest, including surface energy balance, soil moisture, nutrient cycling, vegetation composition, and ecosystem productivity.
• #### Climate-Induced Community Relocations: Creating An Adaptive Governance Framework Based In Human Rights

The specter of millions of people fleeing their homes because of climate change has sparked an international debate about creating human rights protections for climate refugees. Though scholars and journalists have focused on the southern hemisphere, this crisis is occurring with unprecedented rapidity in the Arctic. In Alaska, temperatures have increased at twice the rate of the global average. Arctic sea ice is decreasing and permafrost is thawing, which is accelerating flooding and erosion. These environmental phenomena are threatening dozens of the 200 indigenous tribes that have inhabited the Alaskan Arctic for millennia. The traditional responses of hazard prevention and disaster relief are no longer protecting communities despite millions of dollars spent on erosion control and flood relief. Community relocation is the only feasible solution to permanently protect the inhabitants of these communities. This dissertation describes the steps that federal, state, and tribal governments have taken to relocate Newtok, Shishmaref and Kivalina, three indigenous communities located along the western coast of Alaska, that have chosen to relocate due to climate change. The policy and practical challenges to relocate these communities are enormous and clearly demonstrate that new governance institutions need to be designed and implemented to specifically respond to climate-induced relocation. This dissertation ultimately proposes the creation of Guiding Principles of Climigration outlining key human rights principles that can guide an adaptive governance framework. This framework, in turn, will allow government agencies to dynamically transition their humanitarian response from protection in place to community relocation in these cases.