• Benzene as an indoor air pollutant in Fairbanks, Alaska

      Ricker, Janet Elaine (2000-08)
      Benzene is a known carcinogen found in gasoline, automobile exhaust, cigarette smoke, and organic solvents. Previous studies suggest that sources of chemicals within the home are the major factors influencing personal exposure to benzene. Indoor air was sampled for benzene in order to determine the concentrations present in Fairbanks homes, and to indentify what factors might be associated with higher concentrations. Sampling sites were limited to homes with attached garages and with no smokers in the household. A wide range of benzene concentrations was observed in the eight homes sampled. The highest concentration was about 70 ppbv, and the concentration in most homes was at or above 4 ppbv. The primary source of benzene appears to be gasoline, most likely from small engines (such as lawnmowers) stored in the attached garage. More sites, including homes with attached garages that contain various numbers of small engines, need to be sampled to confirm these conclusions.
    • Best practices and metrics for virtual reality user interfaces

      Byam, Jay; Chappell, Glenn; Lawlor, Orion; Metzgar, Jonathan (2019-12)
      Virtual Reality (VR) technology has become increasingly effective and accessible within the past decade [15]. With this increase in the technology’s prevalence and cultural significance, certain interaction techniques and design choices have emerged as the most widely used and recommended. This research effort employs a VR experiment in which multiple selection methods, interface placements, and navigation techniques are compared side-by-side, and performance metrics and preference data are collected. Both best practice and to-be-avoided methods are examined, and the performance and preference data is analyzed. Determinations made based on the data gathered are partly in-line with expectations according to best practices, partly inconclusive, and partly contrary to the expected performance and preference results. Results suggest that virtual laser pointers and tapping are equally recommendable selection methods for most VR experiences, hand-mounted menus produce the best results overall, and despite performance advantages, joystick navigation should be avoided in VR due to user comfort concerns.
    • Better understanding of production decline in shale gas wells

      Harongjit, Kananek; Ahmadi, Mohabbat; Patil, Shirish; Dandekar, Abhijit (2014-08)
      Production data from the Eagle Ford shale (an analog to the Alaska Shublik shale) was collected from two neighboring counties and analyzed to correlate well performance with completion parameters including length of horizontal wellbore and number of hydraulic fracturing stages. Thirty-eight dry gas wells with production history range of 18-43 months were analyzed using 6 different decline curve analysis (DCA) models including Arps' exponential, harmonic and hyperbolic, power law exponential (PLE), logistic growth analysis (LGA) and Duong's models. In the matching process, 2/3 of history was used to tune the DCA models and their forecasts were compared to the remaining 1/3 of real history. The matching results were analyzed based on production history length and flow regime to have better understanding of limitations and capabilities of each DCA model. Reservoir simulation models, constructed using range of realistic data and actual completion practices of 4 select wells, were employed to assess reasonable values of remaining reserve and remaining well life that were used as benchmarks for comparison with DCA results. The results showed that there was no strong correlation between well performance (average first year production rate) and the horizontal leg or the number of fracturing stages. This was an indication of extremely heterogeneous medium. In most cases, the accuracy of the DCA models increased when longer production history was used to tune the model parameters. LGA seems to be the most accurate DCA model since it gave the highest matching accuracy 71% of the total wells when using longest history length of 31 months. As the flow regime is concerned, LGA model also performed very well matched in 57% of the wells exhibiting only transient flow and 63% for the wells showing transient flow during early production time followed by boundary-dominated flow during late production. Moreover, the remaining reserve and well life of the select wells predicted by LGA fell into reasonably close range of the estimates from the reservoir simulations.
    • Between us

      Mulcrone, Katherine Jean (2005-05)
      Between Us is the first-person account of Louise Halsey's return to her childhood home after her brothers' tragic motorcycle accident. Her brother Danny lies unconscious, but the strength of their bond grants Louie unexpected encounters with him inside the family home. Her conversations with Danny force Louie to reconsider the issues that have driven her family apart and her role in them. The novel begins with a series of vivid dreams which disconcert Louie and lay the groundwork for her to begin piecing together the unraveling of her family. Current sentiments as expressed and relationships as presented in Louie's conversations with family members are echoed by her memories of past events. Danny's death leads Louie to acknowledge that although rebuilding her family requires difficult work, it is work worth doing.
    • Beyond trending: using risking connection as a framework for moving agency culture toward trauma-informed care

      Healey, Michael J.; Renes, Susan L.; Strange, Anthony; Baker, Courtney; Anahita, Sine (2020-08)
      The prevalence and pervasive impact of adverse childhood experiences (ACEs), and more broadly, trauma, are well supported in the extant literature. Despite this evidence, there remains a significant dearth of formal training and educational programs that prepare staff who work with trauma survivors within complex behavioral health systems. Trauma-informed care (TIC) has moved beyond a trend in the mental health field and is gaining momentum as a leading philosophical paradigm that is being infused as an operational framework for agencies that work with survivors. Risking Connection (RC) is a curriculum-based training program that works with agencies interested in becoming trauma-informed. The current study examined the impact of RC on trainee outcomes for knowledge gain, attitude change, and vicarious trauma (VT) on 119 participants who all work for a therapeutic group home system being operated by a provincial government in Atlantic Canada. The findings in this study suggest that RC is effective in improving knowledge gain and attitude change in a favorable direction toward TIC. The study also supported previous findings associated with the improvement of VT.
    • Bilingual research centers in an Alaska studies classroom

      Sipary, Julia; Siekmann, Sabine; John, Theresa; Martelle, Wendy (2015-12)
    • Bioanalytical Development Of Charged Cyclodextrin Capillary Electrokinetic Chromatography And Microperfusion Sampling To Study Endogenous D-Serine And L-Glutamate Efflux In Brain

      Kirschner, Daniel L.; Greene, Thomas (2009)
      A multitude of studies have revealed specific biological mechanisms that contribute to D-amino acid action and regulation in the mammalian central nervous system. The remarkable increase in our understanding of D-amino acid function and distribution in mammals is in many ways a result of the development of sensitive enantioselective separation strategies that allow for quantification in real biological samples. In capillary electrokinetic chromatography (cEKC) the most powerful chiral resolving agents are anionic cyclodextrins (CDs), yet these have not previously been investigated for chiral bioanalysis of amino acids. The focus of this dissertation research was to investigate for the first time the feasibility of and application of anionic cyclodextrins as resolving agents in bioanalytical chiral separations of amino acids. This dissertation encompasses (1) the development of a new bioanalytical separation utilizing capillary electrophoresis laser induced fluorescence (CE-LIF) with sulfated-beta-cyclodextrin for analysis of D-serine (D-ser) and L-glutamate (L-glu) in mammalian brain, (2) the first synthesis and characterization of 6 members of a new family of single isomer sulfoalkyl cyclodextrins, (3) initial studies on chiral analysis of amino acids using single isomer sulfoalkyl CDs, and (4) development and application of a novel microperfusion sampling approach for acute brain slices and coupling of this method to the developed chiral CE-LIF for studying magnitude and timing of D-ser and L-glu efflux from acute hippocampus in response to modeled cerebral ischemia. The results of these studies demonstrate that (1) anionic CDs are powerful chiral selectors for amino acids and can be applied for sensitive bioanalysis of D-amino acids including D-ser, D-glu, and D-asp in brain samples; (2) single isomer sulfoalkyl CDs can be synthesized by regioselective reaction chemistry; (3) single isomer sulfoalkyl CDs are excellent resolving agents for amino acid analysis and may be valuable for bioanalytical chiral applications; and (4) microperfusion sampling coupled to CE-LIF can be used to analyze dynamic changes in the magnitude and timing of neurochemical efflux from single acute hippocampus slices exposed to modeled ischemia. Results of these latter studies suggest that D-ser and L-glu efflux occurs simultaneously in acute hippocampus with similar timing but differing magnitudes.
    • Bioassay and distribution of thiamine in the sea

      Natarajan, Kottayam Viswanathan (1965-05)
    • Biochemical and microbiological assessments of dried Alaska pink salmon, red salmon and Pacific cod heads

      Biceroglu, Huseyin; Smiley, Scott; Crapo, Charles; Bechtel, Peter J. (2012-05)
      Fish heads are generally considered as unsuitable byproducts for human consumption in the United States. The initial objective was to compare the moisture content and water activity levels on dried pink salmon (Oncorhynchus gorbuscha) and dried red salmon (O. nerka) using different temperature and time integration. The secondary objective was to compare shelf life characteristics, rancidity and mold growth, between dried pink dried salmon and dried Pacific cod (Gadus macrocephalus) heads stored for up to 180 days at the ambient temperature (21°C) for East African seafood markets. The third objective was to assess the antioxidant effects for frozen and dried pink salmon heads stored for up to 60 days. In a preliminary experiment, dried red salmon heads were found unsuitable due to the water activity levels above 0.6. The critical moisture contents were detected around 10% for pink salmon heads and were around 15% for Pacific cod heads to reduce water activity levels below 0.6 in these products. The applicable drying temperatures of 50°C lasting over 50 hours for pink salmon heads and 50°C for over 24 hours followed by 30°C for over 24 hours for Pacific cod heads were found optimal. Dried Pacific cod heads showed shelf stability as a potential dried seafood product. Frozen pink salmon heads had 60 days shelf life, while heads with antioxidant glazing retarded oxidation levels (p <0.05). The antioxidant treatment in dried pink salmon heads kept oxidation levels lower than the acceptable limit up to 60 days. This study provided essential information to improve the utilization of these Alaskan seafood byproducts.
    • Biochemical study of a PSI-LHCI complex and molecular study of fcp genes in the diatom Cylindrotheca fusiformis

      Zhang, Hua; Plumley, Gerard; Boyer, Bert; Duffy, Lawrence K. (2002-08)
      A photosystem I-light-harvesting complex I (PSI-LHCI) was isolated from oxygen-evolving thylakoids of the diatom Cylindrotheca fusiformis. The circular dichroism (CD) spectrum of the complex resembled the photosystem I (PSI) complex of green plants. A single 77K fluorescence emission was observed at 715 nm. The excitation spectrum confirmed that both chlorophyll c and carotenoids were energetically coupled to chlorophyll a. The complex contained PSI reaction center proteins (PsaA/B, the PSI accessory subunit PsaC, and nine light-harvesting complex (LHC) apoproteins including an 18kD and a 17.5kD protein. Photosystem II core polypeptides were not detected by immuno- or silver staining. Taken together, the CD, fluorescence, and protein data indicate that at least nine LHC apoproteins can be specifically associated with PSI in this diatom. Twenty fcp gene sequences that encode fucoxanthin-chlorophyll a/c light-harvesting proteins (FCPs) and three encoded proteins that are similar to a 17.5kD FCP, but it was not possible to conclusively confirm that any of these genes encode proteins associated LHCI.
    • Biochemistry of diatom photosynthetic membranes and pigment-protein complexes

      Martinson, Tracey Ann; Plumley, F. Gerald (1996)
      Diatoms are an ecologically important group of algae in both marine and freshwater systems, but in spite of their significance little is known about the structure of their photosynthetic apparatus. This is due in part to the lack of a highly purified, oxygen-evolving thylakoid membrane preparation. Since thylakoid membranes purified from diatoms using methods developed for green plants did not evolve oxygen, a new procedure was developed for use with diatoms. An oxygen-evolving thylakoid membrane preparation is crucial for the study of photosynthetic pigment-protein complexes from these algae because the stability of the Photosystem I (PS I) and Photosystem II reaction centers was shown to be greatly reduced in thylakoid preparations that did not retain electron transport activity. As a result of the instability of PS I in some thylakoid preparations, a novel chlorophyll-binding complex was isolated that contained only the PsaA polypeptide. The isolation of this complex should prove useful in elucidating the structure of the PS I reaction center in all plants. Immunological and N-terminal protein sequencing methods were used to identify several photosynthetic proteins in the purified thylakoid preparation. These results provided evidence for posttranslational modification of two light-harvesting polypeptides (LHCPs) as well as of the PsaB subunit of the PS I reaction center core. Posttranslational modification of LHCPs and/or of PsaB has not been observed in green plants. In contrast to green plants, PS I in diatoms has been shown to be located in the inner thylakoid membranes. It was hypothesized that proteolytic processing of the C-terminus of PsaB in diatoms may be necessary for the PS I holocomplex to be present in the inner membranes, and that this processing may be responsible for the instability of PS I in purified diatom thylakoids. The existence of a functional, highly purified, and extensively characterized thylakoid preparation from diatoms will promote our understanding of the photosynthetic apparatus in these algae.
    • Biochemistry of diatom photosynthetic membranes and pigment-protein complexes

      Martinson, Tracey A. (1996-05)
      Diatoms are an ecologically important group of algae in both marine and freshwater systems, but in spite of their significance little is known about the structure of their photosynthetic apparatus. This is due in part to the lack of a highly purified, oxygen evolving thylakoid membrane preparation. Since thylakoid membranes purified from diatoms using methods developed for green plants did not evolve oxygen, a new procedure was developed for use with diatoms. An oxygen-evolving thylakoid membrane preparation is crucial for the study of photosynthetic pigment-protein complexes from these algae because the stability of the Photosystem I (PS I) and Photosystem II reaction centers was shown to be greatly reduced in thylakoid preparations that did not retain electron transport activity. As a result of the instability of PS I in some thylakoid preparations, a novel chlorophyll-binding complex was isolated that contained only the PsaA polypeptide. The isolation of this complex should prove useful in elucidating the structure of the PS I reaction center in all plants. Immunological and N-terminal protein sequencing methods were used to identify several photosynthetic proteins in the purified thylakoid preparation. These results provided evidence for posttranslational modification of two light-harvesting polypeptides (LHCPs) as well as of the PsaB subunit of the PS I reaction center core. Posttranslational modification of LHCPs and/or of PsaB has not been observed in green plants. In contrast to green plants, PS I in diatoms has been shown to be located in the inner thylakoid membranes. It was hypothesized that proteolytic processing of the C-terminus of PsaB in diatoms may be necessary for the PS I holocomplex to be present in the inner membranes, and that this processing may be responsible for the instability of PS I in purified diatom thylakoids. The existence of a functional, highly purified, and extensively characterized thylakoid preparation from diatoms will promote our understanding of the photosynthetic apparatus in these algae.
    • Biocomplexity Of Nonsorted Circles In The Low Arctic, Alaska

      Kade, Anja N.; Walker, Donald (2006)
      The vegetation and soils in many arctic tundra regions are influenced by the distribution of nonsorted circles, unique patterned-ground features that dot the well-vegetated tundra landscape. They are flat to dome-shaped, bare soil patches 0.5 to 3 m across and lack a border of stones. Localized soil disturbance due to cryogenic processes creates unusual micro-environments with unique plant communities, slow soil development and deep active layers. The contrast between barren nonsorted circles and the well-vegetated stable tundra provides an ideal opportunity to examine the complex linkages among vegetation, soil and disturbance through cryogenic processes, offering insight into how the tundra system operates. The central goal of this thesis is to understand the complex linkages of the nonsorted-circle system along a natural climate gradient on the North Slope in the Alaskan arctic tundra at different scales, ranging from plot level to regional changes. This thesis examines the interactions among vegetation, soil and cryogenic regime by treating the nonsorted circles within the stable tundra as a single complex system. The thesis presents a formal description and analysis of the plant communities on and off nonsorted circles along the climatic gradient using Braun-Blanquet classification approach. The thesis also studies the physical effects of vegetation, soil organic mat and snow cover on the microclimate of nonsorted circles and the stable tundra along the same climate gradient. The influence of vegetation on cryogenic processes is examined experimentally by manipulating the plant canopy on nonsorted circles. When compared to the stable tundra, nonsorted circles have minimal vegetation cover, resulting in warm soil temperatures and deep thaw depths in summer and allowing for increased ice-lens formation during freeze-up. The resulting frost heave and needle-ice formation at the soil surface maintain the bare surfaces of the circles through soil disturbance. Cryogenic processes dominate the system at the northern sites, while the warmer climate towards the south allows for thick vegetation mats on and off the nonsorted circles, suppressing cryogenic processes. The strength of the interactions among vegetation, soil and cryogenic regime may change under a warming arctic climate, possibly leading to the local disappearance of nonsorted circles.
    • The biodegradation of oil and the dispersant Corexit 9500 in Arctic seawater

      McFarlin, Kelly Marie; Leigh, Mary Beth; Perkins, Robert; Braddock, Joan; Hueffer, Karsten; Prince, Roger (2017-05)
      As oil and gas production continues in the Arctic, oil exploration and shipping traffic have increased due to the decline of Arctic sea ice. This increased activity in the Arctic Ocean poses a risk to the environment through the potential release of oil from cargo ships, oil tankers, pipelines, and future oil exploration. Understanding the fate of oil is crucial to understanding the impacts of a spill on the marine ecosystem. Previous oil biodegradation studies have demonstrated the ability of Arctic and sub-Arctic microorganisms to biodegrade oil; however, the rate at which oil degrades and the identity of indigenous oil-degrading microorganisms and functional genes in Arctic seawater remain unknown. In addition to oil, it is also important to understand the fate and effects of chemicals potentially used in oil spill response. Corexit 9500 is a chemical dispersant that is pre-approved for use in sub-Arctic seawater and is likely the dispersant of choice for spill responders in Arctic offshore environments. Currently no literature exists concerning the biodegradation of Corexit 9500 in Arctic seawater. Here we investigate the fate of oil, chemically dispersed oil, and the chemical dispersant, Corexit 9500, in laboratory mesocosms containing freshly collected Arctic surface seawater. The objectives of these experiments were to calculate the extent and rate of biodegradation (based on GC/MS & LC/MS/MS analysis) and to identify bacteria (determined using 16S rRNA gene sequencing) and genes (based on GeoChip 5.0 microarray) potentially involved in the biodegradation process. Indigenous microorganisms degraded both fresh and weathered oil, in both the presence and absence of Corexit 9500, with oil losses ranging from 36-41% within 28 days and 46-61% within 60 days. The biodegradation of the active components of Corexit 9500, which are dioctyl sodium sulfosuccinate (DOSS) and non-ionic surfactants, was also measured after 28 days. Biodegradation of DOSS was 77% in offshore seawater and 33% in nearshore seawater. Non-ionic surfactants were non-detectable after 28 days. Taxa known to include oil-degrading bacteria (e.g. Oleispira, Polaribacter, and Colwellia) and oilbiodegradation genes (e.g. alkB) increased in relative abundance in response to both oil and Corexit 9500. These results increase our understanding of oil and dispersant biodegradation in the Arctic and suggest that some bacteria may be capable of biodegrading both oil and Corexit 9500. We also sought to understand baseline abundances of taxa known to include oildegrading bacteria and functional genes involved in oil biodegradation in an offshore oil lease area. Aerobic oil-degradation genes (based on GeoChip 5.0 microarray) and taxa (determined using 16S rRNA gene sequencing) known to include oil-degrading bacteria were identified in seawater from the surface, middle, and bottom of the water column. Bacterial community structure differed significantly by depth (surface water vs. bottom water), while the relative abundance of major functional gene categories did not differ with depth. These findings support previous observations that two different water masses contribute to a stratified water column in the summer open-water season of the oil lease area, but indicate that potential function is fairly similar with depth. These results will contribute to understanding the potential for oil biodegradation throughout the Arctic water column and the fundamental microbial ecology of an offshore oil lease area. Together, these mesocosm experiments and in situ studies address important data gaps concerning the fate of spilled oil and Corexit in Arctic seawater. These results provide novel insight into the ability of Arctic bacteria to biodegrade crude oil and Corexit 9500, and suggest similarities between Arctic and temperate deep-sea environments in regards to taxa and functional genes that respond to oil and Corexit.
    • Biodegradation Of Petroleum And Alternative Fuel Hydrocarbons In Moderate To Cold Climate

      Horel, Agota Anna (2009)
      Microbial degradation of hydrocarbon fuels contaminating soil in the Arctic and subarctic environment is a relatively slow process. Nevertheless, due to transportation and logistical limitations in rural Alaska, biodegradation might be the best and cheapest contaminant removal option. The aim of this thesis was to investigate the environmental effects on biodegradation by naturally occurring microorganisms for some innovative hydrocarbon fuels and to determine the overall fate of hydrocarbons in soil, including degradation by fungi and bacteria, volatilization, and transport in the soil. Three major types of fuels were investigated in small scale microcosms and larger soil columns: conventional diesel as a control substance, synthetic diesel (arctic grade Syntroleum) and different types of fish oil based biodiesel. The environmental conditions investigated included different soil types (sand and gravel), different temperatures (constant 6�C, 20�C, and fluctuating between 6 and 20�C), moisture levels (from 2% to 12% GWC), fuel concentrations (from 500 to 20,000 mg fuel/kg soil) and nutrient dosages (0 or 300 mg N/kg soil). Microbial response times and growth phases were also investigated for different inoculum types. Conditions of 20�C, 300 mg N/kg soil, sand, ?4000 mg of fuel/kg soil and ?4% GWC were favorable for bioremediation, with a short lag phase lasting from one day to less than a week, and pronounced peaks of daily CO 2 production between week 2 and 3. At suboptimal conditions, all phases were extended and slow, however at low temperatures steady metabolization continued over a longer time. The relative importance of fungal and bacterial remediation varied between fuel types. Diesel fuel degradation was mainly due to bacterial activities while fish biodiesel degradation occurred largely by mycoremediation. For Syntroleum both bacterial and fungal remediation played key roles. Volatilization contributed up to 13% to overall contaminant removal. In soil columns, degradation was slower than in microcosms, due to an uneven concentration profile of contaminants, nutrients and oxygen with depth. In general, biodegradation showed promising results for soil remediation and the alternate fuel types were more biodegradable compared with conventional diesel fuel.
    • Bioenergetic and economic impacts of humpback whale depredation at salmon hatchery release sites

      Chenoweth, Ellen M.; Atkinson, Shannon; McPhee, Megan; Criddle, Keith; Friedlaender, Ari; Heintz, Ron; Straley, Janice (2018-08)
      Since 2008, humpback whales have been documented depredating hatchery-produced juvenile salmon, a novel prey, at points of their release in Southeast Alaska. The objectives of this dissertation are to determine the spatial distribution, seasonal distribution, and frequency of humpback whale foraging at release sites, determine whether whale presence is affecting the economic productivity of hatchery operations, and compare the bioenergetic benefits for whales feeding on juvenile salmon at hatchery release sites relative to typical prey. Five hatchery release sites were monitored over six years during the spring release season for whale presence/absence, numbers, and behaviors. Linear models were used to determine that for coho salmon, cohorts with frequent humpback whale presence had lower marine survival than cohorts with less or no humpback whale presence, but this was not seen for chum or Chinook salmon. Over six years, these sites lost an estimated 23% of revenue from coho salmon totaling almost a million dollars per year in addition to increased rearing costs to mitigate whale predation. A process model was developed to compare the net energy gain for humpback whales foraging on krill, herring and juvenile salmon. Whales were found to feed profitably on krill and chum salmon where they occurred in dense enough distributions and on herring when large coordinated groups impeded the escape of prey. Coho salmon typically distributed too diffusely for humpback whales to recuperate the full energetic costs of engulfment, indicating that behaviors such as bubble net feeding may be essential for increasing prey aggregation to an energetically profitable level, or humpback whales may be feeding to mitigate energetic losses. As intraspecific competition increases due to recovery and or changes to prey resources, generalist humpback whales may expand feeding to exploit new and less profitable prey resources.
    • Biogeochemical tracers of change in Pacific walruses past and present

      Clark, Casey; Horstmann, Lara; Misarti, Nicole; Konar, Brenda; Severin, Ken; Lemons, Patrick (2019-05)
      Reduced sea ice and projected food web shifts associated with warming of the Arctic have raised concerns about the future of Arctic species. Pacific walruses (Odobenus rosmarus divergens) use sea ice as a platform for molting, giving birth, and resting between foraging bouts. Exactly how sea ice loss will affect walruses is difficult to predict, due to a lack of information about regional ecosystems and their responses to climate change. The objectives of the research in this dissertation were to 1) examine how walrus diet changed in response to shifting sea ice conditions over the last 4,000 years, with the goal of generating predictions about how current and future ice loss may affect the walrus population; 2) make it easier to directly compare the results of retrospective and contemporary stable isotope studies of walruses; and 3) generate new tools to assist wildlife managers in monitoring the walrus population in an uncertain future. Stable carbon and nitrogen isotope ratios of walrus bone collagen indicated that diet was similar during previous intervals of high and low sea ice; however, diet variability among individual walruses was greater when sea ice cover was low, suggesting decreased abundance of preferred mollusk prey. Modern walrus diet was different from both previous high and low ice intervals, meaning that food webs in the Arctic are still in a state of flux, or that recent changes are novel within the last 4,000 years. Tissue-specific stable isotope discrimination factors were generated for walrus muscle, liver, skin, and bone collagen to improve comparisons between retrospective and contemporary studies of walrus diet. Additionally, lipid normalization models were parameterized for walrus skin and muscle, thereby making future walrus stable isotope research more feasible by reducing analytical costs and allowing the use of non-lethal sample collection. Finally, a novel technique for estimating the age at onset of reproductive maturity using concentrations of zinc and lead in the teeth of female walruses was established. This new approach has the potential to become a powerful tool for monitoring the walrus population and may be applicable to other species. Use of this technique on archived specimens may make it possible to examine changes in wildlife population dynamics across thousands of years.