• Characterizing wintertime aerosol composition and sulfate formation in Fairbanks, Alaska

      Davey, Ragen; Mao, Jingqiu; Simpson, William R.; Guerard, Jennifer J. (2020-05)
      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.
    • Decadal scale vegetation maps for the boreal forest surrounding Fairbanks, Alaska

      Huhman, Hannah E.; Prakash, Anupma; Rosselló, Jordi Cristóbal; Dewitz, Jon (2018-08)
      Vegetation maps of a selected area within the boreal forest surrounding Fairbanks, Alaska, have been generated for the nominal years of 1985, 1995, 2005, and 2015 using Landsat 4 and 5 Thematic Mapper and Landsat 8 Operational Land Imager surface reflectance products at 30 meter spatial resolution using a decision tree classification. The maps include 9 U.S. Geological Survey (USGS) vegetation classes, as well as barren land, open water, and ice/snow classes that are consistent with the classes identified in the 2001 National Land Cover Database (NLCD) map of Alaska generated by the USGS. Classification steps are based on USGS methodology, with refinements for the boreal forest, to ensure further comparison to the 2001 USGS NLCD map for Alaska. The overall weighted accuracies of first order estimates of data quality using cross validation are 93.2%, 88.4%, 93.3%, and 86.9% for the nominal years of 1985, 1995, 2005, and 2015 maps, respectively, compared to 81.8% accuracy for the USGS NLCD 2001 product. This study demonstrates that the spatial and spectral resolution of Landsat data is the best available for mapping the vegetation of Alaska's boreal forest at 1:50,000 scale. It also shows that the boreal forests surrounding Fairbanks, Alaska have witnessed a decrease in the growth of evergreen forests, an expansion of shrub and an increase in wetland distribution, all of which have been reported as impacts of a warming climate in the Arctic and Sub-arctic.
    • Effects of diet quality and quantity on caribou and reindeer (Rangifer tarandus)

      Thompson, Daniel Paul; Barboza, Perry S.; Parker, Katherine L.; Kielland, Knut; Hundertmark, Kris J. (2013-05)
      Caribou and reindeer (Rangifer tarandus) encounter natural and anthropogenic disturbances across the landscape. In late winter, Rangifer encounter acute food from disturbances such as icing events. Furthermore, as shrubs expand into the Arctic tundra, the proportion of low quality browse may increase in the summer diet of Rangifer. This study evaluated how Rangifer tolerate 1) fluctuations in food quantity in late winter and 2) changes in forage quality over the summer. Rangifer can compensate for food shortages by increasing intake after restriction, which would allow animals to restore body mass quickly during migration. High body fat reserves increase the tolerance of food shortages. During the summer, Rangifer can consume exclusively browse to meet daily energy requirements; however, low nitrogen supply and high toxin load would require the use of alternative forages to supplement nitrogen and reduce toxins.
    • Gold and base metal mineralization of the Dolphin intrusion-related gold deposit, Fairbanks Mining District, Alaska

      Raymond, Luke M.; Newberry, Rainer; Larsen, Jessica; Keskinen, Mary (2018-08)
      The Dolphin deposit is an intrusion-related gold deposit (IRGD) located approximately 30 km north of Fairbanks, Alaska. The deposit is in--and adjacent to--a composite mid-Cretaceous pluton intruding amphibolite facies metamorphic rocks. An NI43-101 compliant gold resource estimation for the deposit (utilizing a 0.3 g/t cut-off grade) is 61.5 Million tonnes (Mt) at 0.69 g/t indicated (1.36 million oz = Moz) and 71.5 Mt at 0.69 g/t inferred (1.58 Moz). Due to extensive hydrothermal alteration of the intrusion, identifying rock types in hand sample and thin section, as well as by standard compositional techniques (e.g., SiO₂ vs. Na₂O + K₂O), has proven problematic. By plotting wt % TiO₂ vs. P₂O5 obtained from XRF analyses and four-acid digest ICP-MS data, two distinct population clusters appear. By comparison with least-altered intrusive rock analyses from the Fairbanks district, the igneous units were originally granite and tonalite. Because there is no gradational transition through an intermediate granodiorite unit, they were most likely derived from two separate magmatic bodies rather than in-situ fractionation from a single parent. Tonalite is concentrated along the northern and eastern margins of the stock with granite composing the rest of the body. Tonalite xenoliths in granite and granite dikes intruding tonalite prove that tonalite is the older unit. Investigations of hydrothermal alteration (based on chemical analyses, X-ray diffraction, and thin section examination) show albitic and advanced argillic (kaolinite-quartz) alteration are the dominant styles with sericite common throughout. Advanced argillic is a low temperature (<300°C) low pH alteration style that has not been previously identified in intrusion related gold deposits (IRGDs) in interior Alaska. Albitic alteration probably resulted from higher temperature, more neutral pH fluids. Gold investigations show that gold occurs as coarse-grained Au°, aurostibite, and maldonite in quartz + sulfide veins; fine-grained Au° in the oxide zone; and in many forms in disseminated sulfide. These forms include Au° inclusions in pyrite and arsenopyrite; solid-solution Au within compositionally zoned arsenopyrite; and as Au° nanoparticles in pyrite and probably arsenopyrite. Using UAF's JEOL JXA-8530F microprobe, I found that solid-solution gold occurs only in arsenopyrite with strong compositional zoning. Such grains are always small (< 0.2 mm) and commonly have low As cores; gold- bearing mantles with moderate % As; and higher As rims. In contrast, compositionally homogenous arsenopyrite does not contain detectable solid-solution gold. Pyrite is commonly arsenian and carries dissolved gold (if any) near detection limits. Gold mineralization has not been tied to any one lithology or alteration style; however, gold does seem to correlate with abrupt changes in alteration, especially between sericite + albite and kaolinite + sericite alteration. Gold-bearing, zoned arsenopyrite is predominantly associated with advanced argillic alteration and apparently represents a rapid growth, disequilibrium phenomenon.
    • Vitamin D, cognitive function, and oxidative stress: clues to overtraining syndrome?

      Jerome, Scott P.; Reynolds, Arleigh J.; Duffy, Lawrence K.; Sheppard, Dani K.; Watts, Phillip B. (2018-05)
      Overtraining syndrome (OTS) is characterized by an unexplainable drop in athletic performance. It affects primarily elite, endurance athletes, though sub-elite athletes are also affected. Although the deterioration in performance is often the most pronounced and troublesome symptoms for athletes, others range from severe fatigue and insomnia to depression and lack of mental concentration. There is no known diagnostic tool except for ruling out all other possible explanations for the abnormal performance. The only known remedy for OTS is rest. Some recover within months while others take a year or more. Some athletes never fully recovery and never return to pre-OTS performance levels. The exact mechanism behind OTS is unknown. Consensus has been reached among exercise science professionals that 1) an imbalance between stress load and recovery leads to OTS; 2) OTS exists on a spectrum of possible outcomes from different exercise/rest ratios; and 3) exercise is only one part of systemic stress that can lead to OTS. In addition to physical exercise, other factors such as environmental conditions, family dynamics, schoolwork, job stressors, and social pressures all contribute to the total stress load on the body. A severe and sustained imbalance between stress and rest is a likely contributor to OTS in athletes. I investigated biomarkers and psychological markers that, in concert, could be used to identify athletes who are at the greatest risk for developing OTS before the onset of symptoms. I examined vitamin D, cognitive function, and oxidative stress status in university cross country skiers in addition to athletic performance status during the competitive ski season. This study's results support three primary conclusions. First, collegiate endurance athletes are more prone to vitamin D insufficiency and deficiency than their sedentary counterparts. Second, collegiate cross country ski racers in the circumpolar North are unlikely to maintain adequate vitamin D during a competition season. Furthermore, vitamin D levels are likely to drop in the post-season, recovery period. Third, cognitive function is likely to be significantly higher in the post-season than during the competition season. Fourth, those who experienced a drop in performance during the competition season are more likely to show signs of oxidative stress. These findings may help to produce a screening tool for OTS.