ScholarWorks@UA

ScholarWorks@UA is University of Alaska's institutional repository created to share research and works by UA faculty, students, and staff.

 

 

  • USE OF ASTM C1512 FOR EVALUATING FOAM BOARD INSULATION USED IN ROADWAY PROJECTS

    Goering, Douglas (2024-02)
    This work focuses on the performance of Expanded Polystyrene and Extruded Polystyrene insulation used in roadway embankments. Insulated roadways have been used in Alaska since the 1960’s and have become ubiquitous in more recent roadway projects. These insulation layers are used to provide a thermal barrier that reduces frost heave and/or reduces permafrost thaw beneath the embankment. Both frost heave reduction and permafrost protection are dependent on an effective insulation layer that limits heat transfer into and out of the base layers of the embankment. It is well known that accumulated moisture in insulation layers can significantly reduce their thermal performance and, thus, reduce their ability to protect embankments. Existing Alaska Department of Transportation Standard Specifications for Highway Construction require that polystyrene insulation boards have a minimum thermal resistance (R-value) of 4.5 per inch thickness, and that they are able to withstand a 24-hr water immersion test with a limited amount of moisture ingress. However, short-term immersion tests are not well-suited to predict the long-term accumulation of moisture that occurs in insulation installed in embankments. A potentially better method for testing insulation moisture ingress under roadway embankment conditions consists of the use of ASTM C1512 which relies on moisture vapor diffusion rather than direct immersion to introduce water into the insulation. A modified version of ASTM C1512 is used in this study to better understand moisture ingress into polystyrene insulation samples and the implications for thermal performance of the products.
  • Hydroclimate drives seasonal riverine export across a gradient of glacierized high-latitude coastal catchments

    Jenckes, J.; Munk, L. A.; Ibarra, D. E.; Boutt, D. F.; Fellman, Jason; Hood, Eran (American Geophysical Union, 2023-04-14)
    Glacierized coastal catchments of the Gulf of Alaska (GoA) are undergoing rapid hydrologic fluctuations in response to climate change. These catchments deliver dissolved and suspended inorganic and organic matter to nearshore marine environments, however, these glacierized coastal catchments are relatively understudied and little is known about total solute and particulate fluxes to the ocean. We present hydrologic, physical, and geochemical data collected during April–October 2019–2021 from 10 streams along gradients of glacial fed to non-glacial (i.e., precipitation) fed, in one Southcentral and one Southeast Alaska region. Hydrologic data reveal that glaciers drive the seasonal runoff patterns. The ẟ18O signature and specific conductance show distinctive seasonal variations in stream water sources between the study regions apparently due to the large amounts of rain in Southeast Alaska. Total dissolved solids concentrations and yields were elevated in the Southcentral region, due to lithologic influence on dissolved loads, however, the hydroclimate is the primary driver of the timing of dissolved and suspended yields. We show the yields of dissolved organic carbon is higher and that the δ13CPOC is enriched in the Southeast streams illustrating contrasts in organic carbon export across the GoA. Finally, we illustrate how future yields of solutes and sediments to the GoA may change as watersheds evolve from glacial influenced to precipitation dominated. This integrated analysis provides insights into how watershed characteristics beyond glacier coverage control properties of freshwater inputs to the GoA and the importance of expanding study regions to multiple hydroclimate regimes.
  • Bellwethers of change: population modelling of North Pacific humpback whales from 2002 through 2021 reveals shift from recovery to climate response

    Cheeseman, Ted; Barlow, Jay; Acebes, Jo Marie; Audley, Katherina; Bejder, Lars; Birdsall, Catlin; Bracamontes, O. S.; Bradford, Amanda L.; Byington, Josie; Calambokidis, John; et al. (The Royal Society, 2024-02-28)
    For the 40 years after the end of commercial whaling in 1976, humpback whale populations in the North Pacific Ocean exhibited a prolonged period of recovery. Using mark–recapture methods on the largest individual photo-identification dataset ever assembled for a cetacean, we estimated annual ocean-basin-wide abundance for the species from 2002 through 2021. Trends in annual estimates describe strong post-whaling era population recovery from 16 875 (± 5955) in 2002 to a peak abundance estimate of 33 488 (± 4455) in 2012. An apparent 20% decline from 2012 to 2021, 33 488 (± 4455) to 26 662 (± 4192), suggests the population abruptly reached carrying capacity due to loss of prey resources. This was particularly evident for humpback whales wintering in Hawai‘i, where, by 2021, estimated abundance had declined by 34% from a peak in 2013, down to abundance levels previously seen in 2006, and contrasted to an absence of decline in Mainland Mexico breeding humpbacks. The strongest marine heatwave recorded globally to date during the 2014–2016 period appeared to have altered the course of species recovery, with enduring effects. Extending this time series will allow humpback whales to serve as an indicator species for the ecosystem in the face of a changing climate.
  • Negotiated Success: Contractual Benefits that Enhance Recruitment and Retention

    Amor, Hella Bel Hadj; Corey, Staci; Jean DeFeo, Dana (Alaska Department of Education & Early Development, 2023-05)
    This report summarizes monetary and non-monetary items used in Collectively Bargained Agreements (CBAs) to enhance retention and recruitment of educators in and outside of Alaska. This report is one of a series commissioned by the Alaska Department of Education and Early Development to support a stakeholder-informed action plan to address the state’s recurring critical challenges in recruiting and retaining teachers. To approach this task, we narrowed our focus to a review of provisions contained within CBAs in Alaska and a sample of districts in the nation, reviewed relevant literature, and collected stakeholder feedback to further inform the report content and organization. We restrict our analysis to the information contained in CBAs, which are negotiated at the district level, with the noted limitation that CBAs are not exhaustive of all educator benefits (e.g., retirement is an important benefit that is managed at the statewide level). The report details benefits in five broad categories and 15 subcategories, which are bookmarked in this abstract for easy access: coming and staying (signing bonus, longevity/retention bonus); benefits – health and wellbeing (healthcare, sick leave, other leave); benefits – moving and living (travel and relocation, housing and utilities, childcare); knowledge and growth (transferable experience, education and certification, professional development); and work life (contract length and workday, extra duties, hard-to-staff areas, performance pay). Overall, we find that benefits and compensation vary significantly across districts in Alaska, and even more substantially across districts in the national sample, reflecting the diversity in the sample in terms of state, region, size, and location.
  • Macroalgal input into the coastal food web along a gradient of seasonal sea ice cover along the Western Antarctic Peninsula

    Iken, Katrin; Amsler, Charles D.; Gorman, Kristen B.; Klein, Andrew G.; Galloway, Aaron W. E.; Amsler, Margaret O.; Heiser, Sabrina; Whippo, Ross; Lowe, Alexander T.; Schram, Julie; et al. (Inter-Research, 2023-09-07)
    Coastal food webs that are supported by multiple primary producer sources are considered to be more stable against perturbations. Here, we investigated how declining macroalgal abundance and diversity might influence coastal food web structure along an annual sea ice cover gradient along the Western Antarctic Peninsula (WAP). The most common benthic invertebrate consumers, macroalgae, and surface particulate organic matter were collected at 15 stations along the WAP. Stable carbon and nitrogen isotope values of primary producers changed negligibly in relation to the sea ice cover gradient, while isotope values of most invertebrate feeding groups increased with higher sea ice cover, although at low explanatory power. Food web length became shorter and consumer trophic niche width smaller in regions with higher sea ice cover. Changes in food web structure were mostly associated with shifts in trophic position of lower trophic levels. Food web structure in higher ice-covered regions resembled that of more generalist feeders with a loss of specialist species, concurrent with an increased reliance on a more reworked detrital food source. These results suggest that a number of benthic invertebrates are able to adjust to differences in basal energy sources. Conversely, these food webs dominated by generalist feeders are likely less efficient in energy transfer, which can create less-stable systems with lower adaptive capacity to disturbance. The predicted sea ice loss along the WAP may ultimately lead to a longer food web with higher macroalgal abundance, more specialist species, and wider consumer trophic niches in the currently more ice-covered regions.

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