This dissertation concentrates on the controlling factors on the instability of the Laurentide Ice Sheet (LIS) and their effects on abrupt climate change. Northern Hemisphere climate fluctuated abruptly during the last deglaciation possibly related to variability in Atlantic meridional overturning circulation (AMOC) and reduced aerial extent of the LIS. Reductions...
Elevated groundwater nitrate (NO3
-) concentrations in the Southern Willamette
Valley (SWV) caused the Oregon Department of Environmental Quality (ODEQ) to
declare a Groundwater Management Area (GWMA) in Spring, 2004. To better
understand direction of groundwater flow, groundwater age, and nitrate transport
pathways of the SWV we developed a steady-state...
Groundwater nitrate contamination is a well-documented issue in the Southern Willamette Valley (SWV) of Oregon, as a Groundwater Management Area (GWMA) has recently been declared. As a GWMA, groundwater nitrate monitoring must occur until regional concentrations are below 7 mg/L NO3-N. However, the presence of temporal variability can make it...
Quantitative resistance (QR) to disease is usually more durable than qualitative resistance, but its genetic basis is not well understood. We used the barley/barley stripe rust pathosystem as a model for the characterization of the QR phenotype and associated genomic regions. As an intermediate step in the preparation of near-isogenic...
Metal and hydrogen ion acidity and extreme nitrate concentrations typical of
Department of Energy (DOE) legacy waste sites pose formidable challenges to
successful implementation of in situ bio-immobilization. Intermediate-scale (~ 2.5 m),
flow through models of an in situ bio-barrier were constructed to investigate U and Tc
removal from groundwater...
Few studies have examined both long-term and fine-scale spatial variations in
water quality of small streams in the Pacific Northwest. As such, a case study was
conducted to determine if current physical and chemical properties of water in three
streams located in the Oregon Coast Range differed from historically measured...
Forest roads produce fine sediment with traffic during wet weather. If the forest road is connected to a stream it can be a source of turbidity and fine sediment that may be detrimental to aquatic organisms especially salmonids.
The goal of this work was to investigate turbid runoff during wet-weather...
Alcoves in some river systems are cooler than the mainstem of the river and provide thermal refugia for aquatic species. An energy balance and sensitivity analysis on 3 alcoves in the Willamette River, Oregon indicate that alcove size and alcove flux determine the degree to which meteorological conditions affect the...
An ASR metric and site rating index applied to over 120 municipal and agricultural locations across Oregon, combined with comparison to case study data from existing ASR sites, indicate that more than 50% of selected sites are hydrogeologically suitable for ASR. The ASR metric is a ratio of aquifer storage...
Abstract Watershed-scale fate/transport modeling of contaminants is a tool that scientists and land managers can use to assess pesticide contamination to stream systems. The Catchment Modeling Framework (CMF) is a catchment-scale fate/transport modeling tool. It was developed to help scientists and land managers assess the effects of possible land-use decisions...