• The Physical Dynamics Of Patterned Ground In The Northern Foothills Of The Brooks Range, Alaska

      Overduin, Pier Paul; Kane, Douglas L. (2005)
      Periglacial landforms, called patterned ground, change the vegetation, microtopography and organic content of the surface soil horizons. Because they are uniquely products of the periglacial environment, changes in that environment affect their distribution and activity. As surface features, they mitigate heat and mass transfer processes between the land and atmosphere. For environmental change detection, the state of the soil and active layer must be monitored across temporal and spatial scales that include these features. It is suggested here that changes in the state of the active layer due to the abrupt spatial changes in surface soil character lead to changes in the distribution of soil components, soil bulk thermal properties and the thermal and hydrological fluxes result. The determination of soil volumetric moisture content using the relative dielectric permittivity of the soil is extended to include live and dead low-density feathermoss. High temporal resolution monitoring of the thermal conductivity of mineral and organic soil horizons over multiple annual cycles is introduced, along with a new method for analyzing the results of transient heat pulse sensor measurements. These results are applied to studies of frost boils and soil stripes in the northern foothills of the Brooks Range in Alaska. Active layer ice dynamics determine the thermal properties of the frozen soil in the frost boil pedon. Annual heaving and subsiding of the ground surface reflects these changes in ice content and can be used to estimate active layer ice content as a function of depth. These estimates correlate with bulk soil thermal diffusivity, inferred as a function of depth from temperature data. Differences in soil thermal diffusivity determine thaw depth differences between frost boil and tundra, and between wet and dry soil stripes. For the latter, deeper subsurface flow through the high organic content wet stripes is delayed until mid-summer; when it does occur, it has a large component normal to the hillslope as a consequence of differential heave. Dynamics in these periglacial landforms can be identified from surface features, highlighting the potential for scaling up their net effect using remote sensing techniques.
    • Improved Membrane Filtration For Water And Wastewater Using Air Sparging And Backflushing

      Psoch, Christian (2005)
      The goal of this research was to investigate methods and techniques that enhance mass transfer through the membranes. Two general types of fluids were investigated: synthetic wastewater treated in a membrane bioreactor (MBR) and natural and simulated river water. For both fluids, a wide range of solid concentrations (up to 18 g/L) were tested. The membranes investigated were all tubular modules at pilot scale between 0.75 and 1.20 m length, with tubular diameters of 5.5--6.3 mm, 0.2 mum pore size, and membrane surface areas of 0.036--0.1 m2. For flux enhancement, two techniques were applied: air sparging (AS), and backflushing (BF). Both techniques were compared with the sponge ball cleaning method. The experimental temperature ranged between 10 and 30�C, cross-flow velocities (CFV) ranged between 0.5 and 5.2 m/s, and transmembrane pressure (TMP) ranged between 30 and 350 kPa. Research results showed, that AS was able to enhance the conventional flux over weeks to months up to factor of 4.5 for river water and a factor of 3 for wastewater. At modest CFV of 1.5--2 m/s, AS was as successful as BF. If higher CFV (up to 5.2 m/s) were supplied for BF, this technique could enhance the wastewater flux by factor 4.5. The supply of AS and BF combined was superior to the single application even at moderate CFV. The major finding of this research was that cake thickness on the membrane surface was decreased by AS, contrary to research by other authors. AS can be used as substitute aeration in MBRs, without impairing the degradation performance. The combination of AS and BF generated the least filter cake, but the lowest fouling was observed for AS. An empirical equation was proposed to calculate the viscosity in a sidestream MBR depending on reactor temperature and mixed liquor suspended solids (MLSS).
    • A comparison of northern research basins and their landscape characteristics

      Kitover, Danielle C. (2005-05)
      In 2004, a Northern Research Basins (NRB) workshop was coordinated to synthesize water balance research of experimental watersheds. This study examined 10 of those basins more closely. Their landscape features were of special interest as past research has attributed one or more of these characteristics to watershed hydrology. However, the key question posed by this study was how such landscape features influence the water balance of northern basins. Water balance characteristics of a basin may be quantified using the runoff ratio (Q/P) and the ET ratio (ET/P). This study linked those parameters to landscape attributes using both conceptual methods and statistical analysis. The hypothesis was that landscape characteristics of the research basins examined in this study will exhibit identifiable trends in the annual water balance of those research basins. Landscape features are divided into two modes. The first was qualitative characteristics considering permafrost extent, major vegetation type, and soil texture. The second was quantitative characteristics, inferred from a series of terrain indices extracted from DEMs. This research demonstrated that although most features included in this study play some role in the hydrology of northern basins, some were more prominent than others. Overall, the water balance of northern basins is effected by the components of latitude, climate, and topography.
    • A model of soil organic matter quality under anaerobic conditions in Arctic and subarctic soils

      Andersen, Sarah (2005-05)
      The extent of anaerobic respiration by soil microbes is dependent on many factors, including water and nutrient availability, pH, temperature, oxidation/reduction potential, and soil organic matter quality. An understanding of the influence of these factors on anaerobic respiration is important as carbon dioxide (CO₂) and methane (CH₄) can act as greenhouse gasses. This study investigated the relationship between soil organic matter (SOM) and anaerobic respiration potential in arctic and sub-arctic soils. A model was developed to describe the dependence of anaerobic gas production on SOM properties. The model was generated by correlating SOM properties to anaerobic gas production for a suite of soils collected from the U.S., Canadian, and Scandinavian Arctic and Subartic. The SOM properties were characterized using pyrolysis-gas chromatography/mass spectrometry. The anaerobic gas production was measured using laboratory incubations. This model was then applied to soil samples taken from the Smith Lake Methane Flux Site at the University of Alaska Fairbanks in order to predict the anaerobic respiration gas production potential from soils in this area. Maps were constructed showing the predicted amount of anaerobic respiration within a 0.75 mile radius of the Smith Lake Methane Flux Site.
    • Floodplain assessment for the Teklanika and Toklat River project reaches in Denali National Park and Preserve, Alaska

      Schalk, Brian N. (2005-05)
      The National Park Service (NPS) is required to assess risks of flooding to existing and proposed structures within the boundaries of the NPS system. Within Denali National Park and Preserve (DNP & P), there are several large, braided rivers that require floodplain management. The objective of this investigation is to provide DNP & P with guidelines and methods that apply fluvial geomorphic, hydrologic, and hydraulic analysis in order to delineate flood hazard zones on this type of stream. Data collected from Teklanika and Toklat Rivers were used to develop a return period versus flood depth/bankfull depth curve and assess potential streambank erosion. Site specific data combined with this curve will enable NPS personnel to easily approximate flood hazard zones for the project reaches. The method can be applied to assess other flood hazard zones associated with other braided rivers with similar characteristics.
    • Ground-water capture-zone delineation: method comparison in synthetic case studies and a field example on Fort Wainwright, Alaska

      Ahern, Julie Anne (2005-05)
      Ground-water capture zone delineation is an integral part of the recent Source Water Assessments performed nation-wide. Delineations are used to identify where protection from contamination is critical. The objectives of our study were to compare commonly-used methods by quantifying the differences in capture-zone areas and evaluating whether the differences increase with system complexity. We delineated capture zones of hypothetical case studies. We began with a very simple hydrogeologic system and gradually added complexity. Four methods were applied to each case: Calculated fixed-radius (CFR), two analytical solutions (WHPA and UFE-Thiem), and a numerical model (MODFLOW). Area comparisons revealed that, in comparison to the numerical model, CFR consistently overestimated, WHP A underestimated, and UFE- Thiem was variable and the most similar. We then compared the methods in a field case on Fort Wainwright, Alaska. As our numerical method, we used a sub-regional ground-water flow model. Area comparisons were similar to case-study results. Surface-water features were the most influential complexity in the field case. We concluded that each method is only as accurate as its assumptions. Any added margin of error must be appropriate for both the aquifer complexities and required assumptions specific to a given ground-water system.
    • Survivability of total coliforms in freezing and frozen soils

      Hrishikesh, Adhikari; Barnes, David L.; Schiewer, Silke; White, Dan (2005-08)
      The study showed that a significant fraction of coliform bacteria survive for more than six months in soil at different temperatures and moisture contents. Survivability of coliform bacteria at subzero temperatures decreased with an increase in moisture content and with an increase in temperature. Total coliform bacteria in soil samples placed outdoors during winter had lower survivability in comparison to samples placed at controlled temperatures below O⁰c. High survivability of total coliform bacteria at controlled, subzero temperatures was assumed to be related to the reduced metabolic activities of the bacteria.
    • Experimental investigation of fiber-reininforced polymer composite bridge deck panel in cold regions

      Choppali, Usha (2005-08)
      To build highway bridges in cold regions like Alaska, cast-in-place concrete has been found to be difficult and expensive, especially in winter seasons. Decked Bulb-Tee bridge members can be heavy and the deck cannot be replaced. On the other hand, fiber-reinforced plastic (FRP) composite materials offer a great opportunity in this area. The primary technical barrier to the use of composite materials in infrastructure applications is lack of data on environmental durability. The present study presents experimental load and strain results of a FRP composite panel that was subjected to cold temperatures. The FRP panel consists of an upper and a bottom laminate tied by a honeycomb core, which was produced by sequentially bonding a flat sheet to a corrugated sheet. Specifically, the objective of this research was to understand the effects of low temperature and low-temperature thermal cycling on the performance of FRP composite bridge deck panels in cold regions. This was achieved by analyzing static tests and results for a FRP deck panel. The research results reported herein showed an increase in stiffness as temperature was lowered up to a certain point, and a reverse trend at a further lower temperature.
    • Estimating seasonal and diurnal variations in influent wastewater characteristics for optimization of activated sludge system in a northern community

      Pinto, Ameet John (2005-08)
      Influent characterization experiments were carried out at the wastewater treatment facility in Fairbanks, Alaska. These experiments were carried out to trace the diurnal and seasonal variations in the influent flow and organic loading rates. A considerable difference in the wastewater flow and organic loading rates was -seen on a seasonal as well as a diurnal basis. The project hypothesized that better understanding of broad influent diurnal and seasonal variations in a wastewater-treatment facility can help optimize control strategies. Based on the observed variations, oxygen production and supply was analyzed as an avenue for optimization in the high purity oxygen activated system. The results indicate that up to 35% excess oxygen was being supplied on the sampling days despite the current control strategy. This excess maybe eliminated by including an upstream measurement device in the treatment scheme to enhance control over the process. Respirometry may improve the plant's ability to make suitable predictions for the oxygen requirements. Benefits of respirometry were discussed and several site-specific recommendations were rnade for the application of respirometric techniques at the Fairbanks wastewater treatment facility.
    • Transport of fecal bacteria in a rural Alaskan community

      Chambers, Molly Katelyn (2005-12)
      People living without piped water and sewer can be at increased risk for fecal-oral diseases. One Alaskan village that relies on hauled water and honeybuckets was studied to determine the pathways of fecal contamination of drinking water and the human environment so that barriers can be established to protect health. Samples were tested for the fecal indicators Escherichia coli and Enterococcus. Several samples were also tested for the pathogens Giardia lamblia and Cryptosporidium parvum. All terrain vehicle (ATV) use and foot traffic transported bacteria within the village and into the home. Surface water flow transported bacteria within the community during spring thaw, but flow from the dump did not appear to contribute to contamination in town. Within the home, viable fecal bacteria were found on waterdippers, kitchen counters and floors, and in washbasin water. Giardia was found at the dump, but not in water from the river adjacent the community. Exposure to fecal contamination could be reduced by cleaning up after dogs, careful disposal of honey bucket bags and gray water, and by protecting stored drinking water.
    • The formation of pore ice in coarse grained soils

      Fourie, Walter (2005-12)
      Understanding the formation of pore ice in coarse grained soils is important to geotechnical and geo-environmental projects such as the construction of roads, airstrips and gravel foundations as well as the treatment of contaminated soils in the arctic, sub-arctic, alpine and northern regions. The amount of pore ice present controls the strength characteristics of the soils as well as the flow of fluid through the soil. Tests have been conducted to qualify the impact of gradation, temperature, compaction and initial moisture content on the formation of pore ice in coarse grained soils. The purpose of this study was to prepare a conceptual model of the freezing mechanism in coarse grained soils and to qualify the parameters that influence the ice formation. Results from this study indicate that the presence of fine grained particles in a coarse grained soil greatly impact the depth at which the pore space initially becomes saturated with ice. A conceptual model was developed and its application is shown with regards to the process of thaw weakening in roads and the creation of preferential flow paths in permeable reactive barriers.
    • Thermokarst evolution and sediment transport study in the Caribou-Poker Creeks Research Watershed, Alaska

      Kodial, Prathap (2005-12)
      The role of sediment transport processes in the development and evolution of cryogenic features like thermo karsts have been overlooked by researchers. The current study is an attempt to better understand sediment transport and associated processes underlying the rapid growth of a thermokarst located in the Caribou-Poker Creeks Research Watershed. Within a short span of two warm summers, the study area has progressed from a hummocky terrain to a well incised channel configuration. Suspended sediment concentration and discharge analyses indicate high sediment flow following precipitation events, which play a major part in the sediment transport process. Mass sediment flows due to cryogenic piping were a result of interflow within the active layer. Fluvio-thermal erosion triggered block failures in the thermokarst. Topographical surveys spanning the two field seasons quantify the upstream erosion rate of more than 3.5 meters per year. Accelerated growth of the thermokarst has made the adjacent areas highly susceptible to secondary geomorphologic features.
    • Dynamic Modeling Of The Hydrologic Processes In Areas Of Discontinuous Permafrost

      Bolton, William Robert; Hinzman, Larry (2006)
      The overarching hypothesis of this dissertation is "in the sub-arctic environment, the presence or absence of permafrost is dominant influence on hydrologic processes." The presence or absence of permafrost is the defining hydrologic characteristic in the sub-arctic environment. Discontinuous permafrost introduces very distinct changes in soil hydraulic properties, which introduce sharp discontinuities in hydrologic processes and ecosystem characteristics. Hydraulic properties vary over short and long time scales as the active layer thaws over the course of a summer or with changes in permafrost extent. The influence of permafrost distribution, active layer thaw depth, and wildfire on the soil moisture regime and stream flow were explored through a combination of field-based observations and computer simulations. Ice-rich conditions at the permafrost table do not allow significant percolation of surface waters, which result in saturated soils near the ground surface and limited subsurface storage capacity, compared to well-drained non-permafrost sites. The removal of vegetation by wildfire results in short-term (<10 years) increases in moisture content through reduced evapotranspiration. Long-term (>10 years) drying of soils in moderate to severe wildfire sites is the result of an increased active layer depth and storage capacity. A spatially-distributed, process-based hydrologic model, TopoFlow, was modified to allow spatial and temporal variation in the hydraulic conductivity and porosity of soils. By continual variation of the hydraulic conductivity (proxy for permafrost distribution and active layer thaw depth) and porosity (proxy for storage capacity), the dynamic soil properties found in the sub-arctic environment are adequately represented. The sensitivity of TopoFlow to changes in permafrost condition, vegetation regime, and evapotranspiration is analyzed. The net result of the field observations and computer simulations conducted in this research suggest the presence or absence of permafrost is the dominant influence on soil moisture dynamics and has an important, but secondary role in the stream flow processes.
    • Biosorption of lead by citrus pectin and peels in aqueous solution

      Balaria, Ankit (2006-05)
      Biosorption of heavy metal ions by different pectin rich materials such as waste citrus peels is emerging as a promising technique for metallic contaminant removal. While binding rate and capacity of citrus peels were previously investigated, there is a lack of mechanistic information about Pb-citrus pectin/peels interaction mechanisms. Present research focused on evaluating this binding mechanism by corroborating macroscopic studies with spectroscopic techniques. Citrus pectins of two different methoxylation degrees and orange peels were characterized using potentiometric titrations and Fourier transform infrared (FTIR) spectroscopy. Binding mechanisms were evaluated using molecular scale FTIR analyses. The effects of particle size, pH, co-ion presence, and background electrolyte concentrations were also investigated for biosorption of Pb by orange peels. Both citrus pectin and orange peels reached their sorption equilibrium within 45 minutes. The maximum uptake capacity for orange peels was found to be 2.32 mmol/g. Citrus peels have very similar FTIR spectra to citrus pectin, suggesting that they have similar functional groups and pectin can be used as a model for citrus peels. Furthermore, carboxylic acid groups were found to be responsible for binding of Pb by citrus pectin and orange peels.
    • Adsorption of Cu (II) and Cd (II) by chininous polymers

      Zhang, Hong (2006-12)
      Heavy metal contamination has emerged as a major health problem worldwide. Biosorption, using biological waste products as sorbents, may provide a cost effective treatment strategy. The current study investigated several types of biomass, generated from waste crab shells, as bio-sorbents to remove cadmium and copper in a batch reaction system. Isotherm studies suggested that uptake increased with increasing number of amine groups, i.e. increasing degree of deacetylation (DDA) as measured by hydrogen nuclear magnetic resonance (¹H-NMR) as well as Fourier Transform Infra-red (FTIR) spectroscopy. Potentiometric titration was shown not to be a valid method in measuring the DDA for medium DDA range. pH was proven to be a main factor affecting the adsorption because of the considerable competition of protons for the binding sites at low pH. Cu²+ had higher affinity than Cd²⁺ to the chitinous polymer. Metal adsorption was elevated by high ionic strength because of more adsorption sites becoming accessible as a result of significant expansion of the network under high ionic strength. Sulfate as salt, added in the solution, greatly stimulated the adsorption of metal ions by reducing the repulsion force between the charged surface and the metal cations.
    • Protecting family drinking water in rural Alaska: improved water management in homes without running water

      Laderach, Shawna R. (2006-12)
      The objective of this study was to investigate and make recommendations for improved in-home water management in an underserved rural Alaskan community without piped water. The main focus of the study is point-of-use disinfection. A model was developed based on experiments to predict the chlorine decay over time and the necessary chlorine dosage for waters used in the pilot community so that sufficient chlorine residual would remain during storage. TOC concentration, initial chlorination level, reduced iron and temperature were major factors impacting the chlorine consumption. Safe free chlorine levels of between 0.2 mg/L and 4.0 mg/L could be achieved in a reasonable time and maintained for typical storage times, while avoiding unpleasant taste. A taste test in the community showed that levels of 1 mg/L or less could not be distinguished by most people and were acceptable for drinking. Storage and hand washing are likely major components of preventing microbial contamination. It was determined that closed containers do not slow the loss of disinfectant from evaporation. Thorough hand washing for at least one minute using soap and running water is recommended, since this was the most effective method to remove coliform bacteria from hands.
    • Experimental Study Of Adsorbed Cation Effects On The Frost Susceptibility Of Natural Soils

      Darrow, Margaret Marie; Huang, Scott; Shur, Yuri (2007)
      Frost heaving is ubiquitous throughout cold regions, causing damage to building foundations, roads, airfields, railways, utilities, and pipelines. Out of the voluminous body of research conducted over the last 80 years, few studies investigated the mineral surface effects on frost heaving. These previous studies were conducted nearly 50 years ago with rudimentary equipment and on homogeneous and artificial soils that have limited applicability to actual field conditions. The purpose of the research presented here is to investigate the adsorbed cation effects on the frost susceptibility of natural soils through experimental testing. A comprehensive suite of laboratory experiments was conducted on five natural heterogeneous soils, including the preparation of divalent and monovalent cation-treated samples. Experimental testing included measurements of engineering index properties, chemical properties, clay content and mineralogy, soil-moisture characteristic curves, unfrozen water content, zeta potential, and frost heave testing. Frost heave tests were conducted using a state-of-the-art laboratory system that demonstrates high repeatability. Soil-moisture characteristic---soil freezing characteristic (SMC-SFC) relations were developed for the five natural soils over an unprecedented range of measurements and using a new approach, which can be related to the Clausius-Clapeyron equation. The SMC-SFC relations yield a new variable, eta, which describes the water retention properties of soil at increasing matric potentials and decreasing temperatures. The five untreated soils demonstrated significantly different frost heave ratios, ranging from 0.7 percent to 49.2 percent. Statistical analysis indicates that the frost susceptibility of the five untreated soils is most dependent on adsorbed cations, eta, amount of microaggregates smaller than 2 mum, and clay content. For the entire body of untreated and cation-treated samples, statistical analysis indicates that the frost susceptibility is most dependent on adsorbed cations, unfrozen water content, and amount of smectite, kaolinite, and chlorite present in the soil. The results from each cation treatment indicate that the frost susceptibility of (1) Ca2+-saturated soil is most dependent on zeta potential and unfrozen water content; (2) Mg2+-saturated soil is most dependent on zeta potential and amount of chlorite; and (3) Na +-saturated soil is most dependent on zeta potential, unfrozen water content, and amount of chlorite.
    • Using Geophysical Constraints To Determine Groundwater Travel Times, Seafloor Arrival Locations, And Saltwater Concentrations For Transition Zone Depths At Underground Nuclear Detonations On Amchitka Island

      Wagner, Anna M.; Barnes, David (2007)
      There is a great amount of radioactive material in the subsurface of Amchitka Island as a result from underground nuclear testing performed between 1965 and 1971. It is unknown how long it will take for the radionuclides to travel to the seafloor and the marine environment or where possible seepage zones will occur. The contaminant transport is greatly affected by the location of the transition zone (TZ) and the effective porosity, which were both determined by magnetotellurics (MT) in 2004. The hypothesis of this study was as follows: the groundwater travel times and seafloor arrival locations, can be estimated through groundwater modeling, with the location of the transition zone being estimated by magnetotellurics. An additional hypothesis is as follows: saltwater concentration for a TZ and the general subsurface characteristics can be quantified with groundwater modeling, using geophysical constraints in combination with saltwater and hydraulic head measurements. The groundwater travel times were estimated with groundwater modeling using the transition zone location as determined by MT. Shortest groundwater travel times are 1,200 and 2,100 years, at Long Shot and Cannikin respectively. At Long Shot, a decreased groundwater travel time of up to 55% could be seen when an enhanced hydraulic conductivity was included at the location of an assumed andesite sill layer. The seafloor arrival locations can be up to 1,000 and 2,100 m offshore at Long Shot and Cannikin respectively but will most likely occur closer to shore. This study was also successful at establishing the general characteristics of the subsurface by using geophysical constraints in combination with saltwater and hydraulic head measurements. The subsurface at Long Shot is isotropic or has mild anisotropy ratio of 1:2, which confirms the study by Fenske (1972). As represented in this study, this method has been shown to be valuable in determining the saltwater concentration of the TZ as determined by MT and can thus be used in further studies of islands and coastal areas.
    • The Influence Of Soil Cryostructure On The Creep And Long Term Strength Properties Of Frozen Soils

      Bray, Matthew Thomas (2008)
      The time dependent mechanical properties of ice-rich frozen soils were studied in relation to their cryostructure. The CRREL permafrost tunnel was the primary source of the studied ice-rich soils. Mapping of the permafrost geology of the main adit of the CRREL permafrost tunnel was performed and reinterpreted in the context of a cryofacial approach. The cryofacial approach in based on the concept that cryostructure is dependent on how a soil was deposited and subsequently frozen. Three main soil cryostructures were determined to represent the main aspects of the permafrost geology. Soils with micro-lenticular cryostructure represent the original ice-rich syngenetic permafrost formed during the Pleistocene. Reworked sediment due to fluvial-thermal erosion resulted in soils with massive cryostructure and soils with reticulate-chaotic cryostructure. Ice bodies within the tunnel include syngenetic wedge ice and secondary thermokarst cave ice deposits. A testing program for determining the time dependent mechanical properties, including the creep and long term strength characteristics of permafrost in relation to soil cryostructure, was performed. Undisturbed frozen soils include silty soil containing micro-lenticular, reticulate-chaotic, and massive cryostructure. Remolded silt from the tunnel was used to create artificial samples with massive cryostructure for comparison to the undisturbed frozen soils. In addition to frozen silt, undisturbed ice facies were tested. These included syngenetic wedge ice, Matanuska basal glacial ice, and Matanuska glacial ice. Testing methods include uniaxial constant stress creep (CSC) tests and uniaxial relaxation tests. It was shown that soil cryostructure and ice facies influences the creep and long term strength properties of frozen soils. It was shown that remolded soils provide non-conservative creep and long term strength estimates when extrapolated to undisturbed frozen soils. Minimum strain rate flow laws show that at low stresses, undisturbed soils creep at a faster rate than remolded soils. At high stresses, frozen soils creep at a faster rate than ice. It was also shown that the unfrozen water content influences the mechanical properties of frozen soils and that the unfrozen water content is influenced by soil cryostructure. Through cryostructure, the permafrost geology is related to the time dependent mechanical properties of frozen soils.
    • The effects of scale and spatial heterogeneities on diffusion in volcanic breccias and basalts: Amchitka, Alaska

      Benning, Jennifer Lyn; Barnes, David; Kelley, John; Perkins, Robert; Schnabel, William (2008-12)
      Aqueous phase diffusion of molecules in fractured crystalline rock can play a dominant role in the fate and transport of contaminants, particularly if advective flows are very slow. The importance of the role of diffusion, typically a very slow process, also becomes an important mechanism to consider if the contaminants are long-lived in the subsurface, and thus their fate and transport must be considered over very long time-scales. Owing to the inherently heterogeneous nature of the subsurface, quantification of diffusive transport in the subsurface is extremely complex. The main objective of this study was to investigate the effects of the inherent heterogeneities of the subsurface on the diffusive transport of radionuclides, with a focus on the former underground nuclear test site at Amchitka Island, Alaska. Commonly, the through-diffusion experiment is utilized to estimate transport parameters, the diffusivity and the effective porosity, for porous media samples. The available methods of mathematically deriving these parameters from these experiments are generally known to be subjective and unreliable. Thus, one phase of this study applied the results of through- diffusion experiments to investigate the applicability of the available solution methods to derive these parameters. The results indicated that a semi-analytical solution provided the most reliable parameter estimations. This knowledge was then applied to studies designed to understand the impacts of scale and spatial heterogeneities on diffusion at the study site. Multiple Amchitka Island core samples, both from the same and from various geologic layers, in varying sizes were analyzed in the laboratory via tracer-based and electrical methods, to quantify the diffusive properties and the effects of heterogeneities for Amchitka Island. The studies indicated that the transport properties for Amchitka Island are widely varying, by orders of magnitude, and are indicative of a geologically layered subsurface system; these results are extremely important for the long-term modeling of the fate and transport of radionuclides at Amchitka Island. Finally, in light of these studies, the question of long-term stewardship for the Amchitka Island test site was investigated and recommendations were provided, with the goal of providing an improved plan for the long-term monitoring and management of the site.