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Filtering by: Creator Wirth, Julie A. Remove constraint Creator: Wirth, Julie A. Committee Member Pett-Ridge, Julie Remove constraint Committee Member: Pett-Ridge, Julie

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  • Influence of a Sedimentary Source of Nd on Deep Ocean εNd Distributions

    Creator:
    Abbott, April N.
    Abstract:
    Ocean circulation is an important component in Earth's climate system. Predicting future climate and circulation changes requires an improved understanding of the past relationship between climate and ocean currents. The neodymium isotope composition (εNd) of water masses is frequently used as a quasi-conservative tracer to reconstruct ocean circulation. The current...
    Resource Type:
    Dissertation

  • Predicting the spatial variability in soil properties using DSM across Malheur National Forest

    Creator:
    Seeno, Elizabeth A.
    Abstract:
    Soil properties may hold the key to improved predictions of soils during digital soil mapping (DSM), which has developed with a focus on environmental factors external to soil. The spatial variability in soil properties was modeled across Malheur National Forest in eastern Oregon as an approach to improve DSM. The...
    Resource Type:
    Masters Thesis
    Full Text:
    using DSM across Malheur National Forest AN ABSTRACT OF THE THESIS OF Elizabeth A. Seeno for the

  • Phosphorus control of nitrogen fixation

    Creator:
    Watkins-Brandt, Katie S.
    Abstract:
    Under conditions of fixed N-limitation, as with most oligotrophic systems, the process of biological N₂ fixation (diazotrophy) is favored, provided the necessary trace elements and vitamins are sufficient. Despite the well understood contributions of N₂ fixation in oligotrophic regions, the nutritional and ecological controls of marine diazotrophs have not been...
    Resource Type:
    Masters Thesis
    Full Text:
    for serving as a committee member and an outside view and Dr. Julie Pett-Ridge for serving as my

  • Soil organic carbon response to six years of warming : assessing the impacts of altered diurnal temperature range

    Creator:
    Murphey, Virginia L. W.
    Abstract:
    There is a growing consensus that anthropogenic warming will impact soil organic matter (SOM). Globally, soil contains 2-3 times more carbon (C) than plants, and like plants, temperature induced change of SOM could have significant climate repercussions. Although, the majority of warming experiments have increased day and night temperatures equally,...
    Resource Type:
    Masters Thesis
    Full Text:
    : ______________________________________________________________________________ Kate J. Lajtha There is a growing consensus that anthropogenic warming will impact soil

  • Calcium Ion Transport via Seeping Flow Events through Epikarst Microfissures

    Creator:
    Windom, Lisa M.
    Abstract:
    Solute transport models in karst groundwater must consider variable and complex flow regimes. Within fissures less than 2 mm in aperture, during unsaturated flow events, seeping flow may flow as films or under capillary tension as a capillary rivulet. This project focuses on exploring the mass transport characteristics of seeping...
    Resource Type:
    Masters Thesis
    Full Text:
    capillary tension as a capillary rivulet. This project focuses on exploring the mass transport

  • Comparison of radiative feedback variability over multiple time scales in climate model and reanalysis data

    Creator:
    Dalton, Meghan M.
    Abstract:
    In a steady state, the Earth's absorbed solar radiation (ASR) balances the outgoing longwave radiation (OLR) at the top of the atmosphere (TOA). In response to a radiative forcing, that is, an external perturbation to the top of the atmosphere energy balance, the Earth's climate system adjusts until reaching a...
    Resource Type:
    Masters Thesis
    Full Text:
    approved: Karen M. Shell In a steady state, the Earth’s absorbed solar radiation (ASR) balances the

  • Lichen Biomonitoring from Valley to Alpine in Central and Southern California

    Creator:
    Kovasi, Adrienne I.
    Abstract:
    In the mountains of central and southern California, high elevation wilderness areas lack epiphytic lichens that can be used to inform us about atmospheric deposition in multiple ways. Epiphytic lichens are capable of accumulating elements proportionally to the local atmospheric concentration, establishing them as commonly used biomonitor of key elements....
    Resource Type:
    Masters Thesis
    Full Text:
    as bioindicators because they remain relatively common into alpine elevations. We compiled a

  • The role of near-stream zones on flow, chemistry and isotopic composition at the headwater scale

    Creator:
    Frentress, Jay
    Abstract:
    Stream discharge is a key water balance component and important factor in global change evaluations. Nevertheless, the mechanisms for streamflow generation are poorly understood. Near- stream surface saturation during precipitation events is one of the most iconic, visible indicators of rapid runoff production in upland humid catchments around the world....
    Resource Type:
    Dissertation
    Full Text:
    : ________________________________________________________________________________________ Jeffrey J. McDonnell Stream discharge is a key water balance component and important factor in

  • Stream Chemistry in the Oregon Coast Range: Spatial and Temporal Variation

    Creator:
    Carini, Lya
    Abstract:
    Hydrological and biogeochemical processes occurring throughout a watershed are typically reflected in stream water chemistry, including in coastal watersheds. While Oregon Coast Range streams have been studied in the past, there is a dearth of knowledge in terms of seasonal temporal trends and spatial variability that this study seeks to...
    Resource Type:
    Masters Thesis
    Full Text:
    processes occurring throughout a watershed are typically reflected in stream water chemistry, including in

  • Diversity and Activity of Microbial Extracellular Peptidases in Soil

    Creator:
    Nguyen, Trang T. H.
    Abstract:
    Soil nitrogen exists largely as organic matter, including plant liter, dead animal matter, and microbial necromass. About 90% of soil organic nitrogen is proteinaceous material that is too large for plants and microorganisms to assimilate directly. Protein depolymerization therefore plays a critical role in mobilizing this organic source of nitrogen,...
    Resource Type:
    Dissertation
    Full Text:
    therefore plays a critical role in mobilizing this organic source of nitrogen, producing lower molecular