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Sample records for alaskan yukon river

  1. Spatial variability and landscape controls of near-surface permafrost within the Alaskan Yukon River Basin

    USGS Publications Warehouse

    Pastick, Neal J.; Jorgenson, M. Torre; Wylie, Bruce K.; Rose, Joshua R.; Rigge, Matthew; Walvoord, Michelle A.

    2014-01-01

    The distribution of permafrost is important to understand because of permafrost's influence on high-latitude ecosystem structure and functions. Moreover, near-surface (defined here as within 1 m of the Earth's surface) permafrost is particularly susceptible to a warming climate and is generally poorly mapped at regional scales. Subsequently, our objectives were to (1) develop the first-known binary and probabilistic maps of near-surface permafrost distributions at a 30 m resolution in the Alaskan Yukon River Basin by employing decision tree models, field measurements, and remotely sensed and mapped biophysical data; (2) evaluate the relative contribution of 39 biophysical variables used in the models; and (3) assess the landscape-scale factors controlling spatial variations in permafrost extent. Areas estimated to be present and absent of near-surface permafrost occupy approximately 46% and 45% of the Alaskan Yukon River Basin, respectively; masked areas (e.g., water and developed) account for the remaining 9% of the landscape. Strong predictors of near-surface permafrost include climatic indices, land cover, topography, and Landsat 7 Enhanced Thematic Mapper Plus spectral information. Our quantitative modeling approach enabled us to generate regional near-surface permafrost maps and provide essential information for resource managers and modelers to better understand near-surface permafrost distribution and how it relates to environmental factors and conditions.

  2. Spatial variability and landscape controls of near-surface permafrost within the Alaskan Yukon River Basin

    NASA Astrophysics Data System (ADS)

    Pastick, Neal J.; Jorgenson, M. Torre; Wylie, Bruce K.; Rose, Joshua R.; Rigge, Matthew; Walvoord, Michelle A.

    2014-06-01

    The distribution of permafrost is important to understand because of permafrost's influence on high-latitude ecosystem structure and functions. Moreover, near-surface (defined here as within 1 m of the Earth's surface) permafrost is particularly susceptible to a warming climate and is generally poorly mapped at regional scales. Subsequently, our objectives were to (1) develop the first-known binary and probabilistic maps of near-surface permafrost distributions at a 30 m resolution in the Alaskan Yukon River Basin by employing decision tree models, field measurements, and remotely sensed and mapped biophysical data; (2) evaluate the relative contribution of 39 biophysical variables used in the models; and (3) assess the landscape-scale factors controlling spatial variations in permafrost extent. Areas estimated to be present and absent of near-surface permafrost occupy approximately 46% and 45% of the Alaskan Yukon River Basin, respectively; masked areas (e.g., water and developed) account for the remaining 9% of the landscape. Strong predictors of near-surface permafrost include climatic indices, land cover, topography, and Landsat 7 Enhanced Thematic Mapper Plus spectral information. Our quantitative modeling approach enabled us to generate regional near-surface permafrost maps and provide essential information for resource managers and modelers to better understand near-surface permafrost distribution and how it relates to environmental factors and conditions.

  3. An estimate of carbon emissions from 2004 wildfires across Alaskan Yukon River Basin

    PubMed Central

    Tan, Zhengxi; Tieszen, Larry L; Zhu, Zhiliang; Liu, Shuguang; Howard, Stephen M

    2007-01-01

    Background Wildfires are an increasingly important component of the forces that drive the global carbon (C) cycle and climate change as progressive warming is expected in boreal areas. This study estimated C emissions from the wildfires across the Alaskan Yukon River Basin in 2004. We spatially related the firescars to land cover types and defined the C fractions of aboveground biomass and the ground layer (referring to the top 15 cm organic soil layer only in this paper) consumed in association with land cover types, soil drainage classes, and the C stocks in the ground layer. Results The fires led to a burned area of 26,500 km2 and resulted in the total C emission of 81.1 ± 13.6 Tg (Tg, Teragram; 1 Tg = 1012 g) or 3.1 ± 0.7 kg C m-2 burned. Of the total C emission, about 73% and 27% could be attributed to the consumption of the ground layer and aboveground biomass, respectively. Conclusion The predominant contribution of the ground layer to the total C emission implies the importance of ground fuel management to the control of wildfires and mitigation of C emissions. The magnitude of the total C emission depends on fire extent, while the C loss in kg C m-2 burned is affected strongly by the ground layer and soil drainage condition. The significant reduction in the ground layer by large fires may result in profound impacts on boreal ecosystem services with an increase in feedbacks between wildfires and climate change. PMID:18093322

  4. An estimate of carbon emissions from 2004 wildfires across Alaskan Yukon River Basin

    USGS Publications Warehouse

    Tan, Z.; Tieszen, L.L.; Zhu, Z.; Liu, S.; Howard, S.M.

    2007-01-01

    Background: Wildfires are an increasingly important component of the forces that drive the global carbon (C) cycle and climate change as progressive warming is expected in boreal areas. This study estimated C emissions from the wildfires across the Alaskan Yukon River Basin in 2004. We spatially related the firescars to land cover types and defined the C fractions of aboveground biomass and the ground layer (referring to the top 15 cm organic soil layer only in this paper) consumed in association with land cover types, soil drainage classes, and the C stocks in the ground layer. Results: The fires led to a burned area of 26,500 km2 and resulted in the total C emission of 81.1 ?? 13.6 Tg (Tg, Teragram; 1 Tg = 1012g) or 3.1 ?? 0.7 kg C m-2 burned. Of the total C emission, about 73% and 27% could be attributed to the consumption of the ground layer and aboveground biomass, respectively. Conclusion: The predominant contribution of the ground layer to the total C emission implies the importance of ground fuel management to the control of wildfires and mitigation of C emissions. The magnitude of the total C emission depends on fire extent, while the C loss in kg C m-2 burned is affected strongly by the ground layer and soil drainage condition. The significant reduction in the ground layer by large fires may result in profound impacts on boreal ecosystem services with an increase in feedbacks between wildfires and climate change. ?? 2007 Tan et al; licensee BioMed Central Ltd.

  5. Distribution and landscape controls of organic layer thickness and carbon within the Alaskan Yukon River Basin

    USGS Publications Warehouse

    Pastick, Neal J.; Rigge, Matthew B.; Wylie, Bruce K.; Jorgenson, M. Torre; Rose, Joshua R.; Johnson, Kristofer D.; Ji, Lei

    2014-01-01

    Understanding of the organic layer thickness (OLT) and organic layer carbon (OLC) stocks in subarctic ecosystems is critical due to their importance in the global carbon cycle. Moreover, post-fire OLT provides an indicator of long-term successional trajectories and permafrost susceptibility to thaw. To these ends, we 1) mapped OLT and associated uncertainty at 30 m resolution in the Yukon River Basin (YRB), Alaska, employing decision tree models linking remotely sensed imagery with field and ancillary data, 2) converted OLT to OLC using a non-linear regression, 3) evaluate landscape controls on OLT and OLC, and 4) quantified the post-fire recovery of OLT and OLC. Areas of shallow (2 = 0.68; OLC: R2 = 0.66), where an average of 16 cm OLT and 5.3 kg/m2 OLC were consumed by fires. Strong predictors of OLT included climate, topography, near-surface permafrost distributions, soil wetness, and spectral information. Our modeling approach enabled us to produce regional maps of OLT and OLC, which will be useful in understanding risks and feedbacks associated with fires and climate feedbacks.

  6. MODIS-informed greenness responsesto daytime land surface temperaturefluctuations and wildfire disturbancesin the Alaskan Yukon River Basin

    USGS Publications Warehouse

    Tan, Zhengxi; Liu, Shu-Guang; Jenkerson, Calli; Oeding, Jennifer; Wylie, Bruce K.; Rover, Jennifer R.; Young, Claudia J.

    2012-01-01

    Pronounced climate warming and increased wildfire disturbances are known to modify forest composition and control the evolution of the boreal ecosystem over the Yukon River Basin (YRB) in interior Alaska. In this study, we evaluate the post-fire green-up rate using the normalized difference vegetation index (NDVI) derived from 250 m 7 day eMODIS (an alternative and application-ready type of Moderate Resolution Imaging Spectroradiometer (MODIS) data) acquired between 2000 and 2009. Our analyses indicate measureable effects on NDVI values from vegetation type, burn severity, post-fire time, and climatic variables. The NDVI observations from both fire scars and unburned areas across the Alaskan YRB showed a tendency of an earlier start to the growing season (GS); the annual variations in NDVI were significantly correlated to daytime land surface temperature (LST) fluctuations; and the rate of post-fire green-up depended mainly on burn severity and the time of post-fire succession. The higher average NDVI values for the study period in the fire scars than in the unburned areas between 1950 and 2000 suggest that wildfires enhance post-fire greenness due to an increase in post-fire evergreen and deciduous species components

  7. Influence of the Yukon River on the Bering Sea

    NASA Technical Reports Server (NTRS)

    Dean, Kenneson G.; Mcroy, C. Peter

    1988-01-01

    Physical and biological oceanography of the northern Bering Sea including the influence of the Yukon River were studied. Satellite data acquired by the Advanced Very High Resolution Radiometer (AVHRR), the LANDSAT Multispectral Scanner (MSS) and the Thematic Mapper (TM) sensor were used to detect sea surface temperatures and suspended sediments. Shipboard measurements of temperature, salinity and nutrients were acquired through the Inner Shelf Transfer and Recycling (ISHTAR) project and were compared to digitally enhanced and historical satellite images. The satellite data reveal north-flowing, warm water along the Alaskan coast that is highly turbid with complex patterns of surface circulation near the Yukon River delta. To the west near the Soviet Union, cold water, derived from an upwelling, mixes with shelf water and also flows north. The cold and warm water coincide with the Anadyr, Bering Shelf and Alaskan coastal water masses. Generally, warm Alaskan coastal water forms near the coast and extends offshore as the summer progresses. Turbid water discharged by the Yukon River progresses in the same fashion but extends northward across the entrance to Norton Sound, attaining its maximum surface extent in October. The Anadyr water flows northward and around St. Lawrence Island, but its extent is highly variable and depends upon mesoscale pressure fields in the Arctic Ocean and the Bering Sea.

  8. Alaskan river environmental acoustics

    NASA Astrophysics Data System (ADS)

    Dahl, Peter H.; Pfisterer, Carl; Geiger, Harold J.

    2005-04-01

    Sonars are used by the Alaska Department of Fish and Game (ADF&G) to obtain daily and hourly estimates of at least four species of migratory salmon during their seasonal migration which lasts from June to beginning of September. Suspended sediments associated with a river's sediment load is an important issue for ADF&G's sonar operations. Acoustically, the suspended sediments are a source of both volume reverberation and excess attenuation beyond that expected in fresh water. Each can impact daily protocols for fish enumeration via sonar. In this talk, results from an environmental acoustic study conducted in the Kenai River (June 1999) using 420 kHz and 200 kHz side looking sonars, and in the Yukon River (July 2001) using a 120 kHz side looking sonar, are discussed. Estimates of the volume scattering coefficient and attenuation are related to total suspended sediments. The relative impact of bubble scattering and sediment scattering is also discussed.

  9. An integrated Dissolved Organic Carbon Dynamics Model (DOCDM 1.0): model development and a case study in the Alaskan Yukon River Basin

    NASA Astrophysics Data System (ADS)

    Lu, X.; Zhuang, Q.

    2015-12-01

    Quantitative understanding of the variation in dissolved organic carbon (DOC) is important to studying the terrestrial ecosystem carbon cycle. This study presents a process-based, dissolved organic carbon dynamics model (DOCDM 1.0) that couples the soil heat conduction, water flow, DOC production, mineralization and transport in both surface and subsurface of soil profile to quantify DOC dynamics in boreal terrestrial ecosystems. The model is first evaluated and then applied for a watershed in Alaska to investigate its DOC production and transport. We find that 42 and 27 % of precipitation infiltrates to soils in 2004, a warmer year, and in 1976, a colder year, respectively. Under warming conditions, DOC transported via overland flow does not show the expected decrease trend while the overland DOC yield shows a 4 % increase. The horizontal subsurface flow only accounts for 1-2 % of total water flux, but transports 30-50 % of DOC into rivers. Water flush due to water infiltration controls DOC transport. Snowmelt plays a noticeable role in DOC flush-out and DOC transport significantly depends on flowpaths in the study region. High soil temperature stimulates DOC production. The overland DOC export does not necessarily follow the DOC downward trend in surface water transport. Overall, this study shows that DOC export behavior is complex under changing temperature and hydrological conditions in cold-region watersheds. To adequately quantify DOC dynamics in northern high latitudes, more DOC and hydrological data are needed to better parameterize and test the developed model before extrapolating it to the region.

  10. Radiometric traverse along the Yukon River from Fort Yukon to Ruby, Alaska, 1949

    USGS Publications Warehouse

    White, Max G.; Stevens, John M.; Matzko, John J.

    1956-01-01

    In 1949, a radiometric traverse was made of rocks exposed along the banks of and near the Yukon River about Fort Yukon to Ruby, Alaska. Granitic rocks of Tertiary age and of Devonian or Carboniferous age and sandstone beds of Cretaceous age gave the highest readings obtained in the field. Other rock types examined were greenstone of Devonian or Carboniferous age and metamorphic rocks of Devonian and pre-Devonian age, sedimentary rocks, and liginite of Tertiary age, and alluvial deposits of Quaternary age. The most radioactive sample, from Melozitna River canyon, contained only 0.017 percent equivalent uranium.

  11. Dissolved Organic Carbon in the Yukon River Basin

    NASA Astrophysics Data System (ADS)

    Aiken, G.; Striegl, R.; Schuster, P.

    2003-12-01

    A critical question in carbon cycling is how climate change could alter the fate and chemical nature of dissolved organic carbon (DOC) released from watersheds and transported to rivers, lakes, estuaries and coastal waters. The spatial and temporal variability of DOC in surface waters associated with the Yukon River Basin is being studied to better define the processes controlling DOC in this system. The Yukon River Basin, a large and diverse ecosystem in northwestern Canada and central Alaska, is experiencing increasing temperatures, partial melting of permafrost, drying of upland soils and changing wetland environments. However, little is known about DOC transported in the system. Specific ultraviolet absorbance (SUVA) measurements, in combination with DOC and DOC fractionation analyses, were used to determine both the amount and nature of DOC in the Yukon River and major tributaries. DOC transported in the Yukon River and its tributaries was seasonally dependent. For example, DOC concentrations in the Yukon River at Steven's Village ranged from 2 to 17 mg C/L during 2003, and SUVA ranged from 2.0 to 3.5 L/mg C m, indicating a large variation in amount and nature of organic matter in the river. Lowest DOC concentrations and SUVA values were observed in winter under low flow conditions. Greatest DOC concentrations were measured on samples collected during the spring on the leading part of the hydrograph. These samples were also found to have the greatest SUVA values indicating that the organic matter transported during this period was more aromatic than DOC transported under low flow conditions. High SUVA values are indicative of greater amounts of organic material originating in soils and wetlands of the watershed. The amount and nature of organic matter transported by the tributaries appeared to be related to relief and wetland contribution to the watershed of the tributary. Based on DOC and SUVA data, the Yukon River tributaries can be classified as dark water

  12. Influence of the Yukon River on the Bering Sea

    NASA Technical Reports Server (NTRS)

    Dean, K.; Mcroy, C. P.

    1986-01-01

    The purpose is to use satellite data to study relationships between discharge of the Yukon River to currents and biologic productivity in the northern Bering Sea. Amended specific objectives are: to develop thermal, sediment and chlorophyll surface maps using thematic mapping (TM) data of the discharge of the Yukon River and the Alaska Coastal Current during the ice free season; to develop a historical model of the distribution of the Yukon River discharge and the Alaska Coastal Current using LANDSAT multispectral scanner (MMS) and NOAA satellite imagery; and to use high resolution TM data to define the surface dynamics of the front between the Alaska Coastal Current and the Bering Shelf/Anadyr Current. LANDSAT MSS and TM, and Advanced Very High Resolution Radiometer (AVHRR) data were recorded during the 1985 ice-free period. The satellite data coincided with shipboard measurements acquired by Inner Self Transfer and Recycling scientists. Circumstances were such, that on July 5 and July 22, all three sensors recorded data that has been registered to a common map projection and map base, then contrast stretched, color composited, and density sliced.

  13. Floodplain Organic Carbon Storage in the Central Yukon River Basin

    NASA Astrophysics Data System (ADS)

    Lininger, K.; Wohl, E.

    2014-12-01

    Floodplain storage of organic carbon is an important aspect of the global carbon cycle that is not well understood or quantified. Although it is understood that rivers transport organic carbon to the ocean, little is known about the quantity of stored carbon in boreal floodplains and the influence of fluvial processes on this storage. We present results on total organic carbon (TOC) content within the floodplains of two rivers, the Dall River and Preacher Creek, in the central Yukon River Basin in the Yukon Flats National Wildlife Refuge of Alaska. The results indicate that organic carbon storage is influenced by fluvial disturbance and grain size. The Dall River, which contains a large amount of floodplain carbon, is meandering and incised, with well-developed floodplain soils, a greater percentage of relatively old floodplain surfaces and a slower floodplain turnover time, and finer grain sizes. Preacher Creek stores less TOC, transports coarser grain sizes, and has higher rates of avulsion and floodplain turnover time. Within the floodplain of a particular river, large spatial heterogeneity in TOC content also exists as a function of depositional environment and age and vegetation community of the site. In addition, saturated regions of the floodplains, such as abandoned channels and oxbow lakes, contain more TOC compared to drier floodplain environments. Frozen alluvial soils likely contain carbon that could be released into the environment with melting permafrost, and thus quantifying the organic carbon content in the active layer of floodplain soils could provide insight into the characteristics of the permafrost beneath. The hydrology in these regions is changing due to permafrost melt, and floodplain areas usually saturated could be dried out, causing breakdown and outgassing of carbon stored in previously saturated soils. Ongoing work will result in a first-order estimate of active-layer floodplain carbon storage for the central Yukon River Basin.

  14. Carbon dioxide and methane emissions from the Yukon River system

    USGS Publications Warehouse

    Striegl, Rob; Dornblaser, Mark M.; McDonald, Cory P.; Rover, Jennifer R.; Stets, Edward G.

    2012-01-01

    Carbon dioxide (CO2) and methane (CH4) emissions are important, but poorly quantified, components of riverine carbon (C) budgets. This is largely because the data needed for gas flux calculations are sparse and are spatially and temporally variable. Additionally, the importance of C gas emissions relative to lateral C exports is not well known because gaseous and aqueous fluxes are not commonly measured on the same rivers. We couple measurements of aqueous CO2 and CH4 partial pressures (pCO2, pCH4) and flux across the water-air interface with gas transfer models to calculate subbasin distributions of gas flux density. We then combine those flux densities with remote and direct observations of stream and river water surface area and ice duration, to calculate C gas emissions from flowing waters throughout the Yukon River basin. CO2emissions were 7.68 Tg C yr−1 (95% CI: 5.84 −10.46), averaging 750 g C m−2 yr−1 normalized to water surface area, and 9.0 g C m−2 yr−1 normalized to river basin area. River CH4 emissions totaled 55 Gg C yr−1 or 0.7% of the total mass of C emitted as CO2 plus CH4 and ∼6.4% of their combined radiative forcing. When combined with lateral inorganic plus organic C exports to below head of tide, C gas emissions comprised 50% of total C exported by the Yukon River and its tributaries. River CO2 and CH4 derive from multiple sources, including groundwater, surface water runoff, carbonate equilibrium reactions, and benthic and water column microbial processing of organic C. The exact role of each of these processes is not yet quantified in the overall river C budget.

  15. Export Fluxes of Dissolved Organic Carbon From the Yukon River

    NASA Astrophysics Data System (ADS)

    Guo, L.; Cai, Y.; Belzile, C.; MacDonald, R.

    2005-12-01

    Quantitative determination of export fluxes of carbon species through Arctic rivers is required to constrain the carbon budget in the Arctic Ocean and to understand the biogeochemical consequence of climate change in Northern drainage basins. In order to quantify the annual riverine export flux from the Yukon River, monthly or bimonthly water samples were collected at Pilot Station from July 2004 to July 2005 and analyzed for concentrations of dissolved organic carbon (DOC), particulate organic carbon (POC) and dissolved inorganic carbon (DIC). Concentration of DOC varied from 182 to 1683 uM (average 441 uM), with the highest concentration during river ice opening and the lowest in April under the ice. In contrast, DIC concentration increased from ice opening in May (1178 uM) to winter frozen season (2128 uM), with an average of 1588 uM. In addition to the DOC maximum during ice opening, an elevated DOC concentration was observed during the early stage of river ice formation, suggesting the rejection of DOC from ice during its formation. There was a positive correlation of DOC with freshwater flow rate whereas DIC correlated negatively with flow, indicating a hydrological control on both components but different source terms and transport mechanisms. Integrated annual export flux during 2004/2005 was 2.78x1012 g-C/y for DOC and 4.53x1012 g-C/y for DIC. Within the annual fluxes, only 5% of DOC and 17% of DIC were exported during the winter period when the river was frozen over. Long-term observations of DOC and DIC together with their molecular and isotopic signatures are needed to understand how the Yukon River Basin responds to a changing climate.

  16. Mercury interferes with endogenous antioxidant levels in Yukon River subsistence-fed sled dogs

    NASA Astrophysics Data System (ADS)

    Dunlap, Kriya L.; Reynolds, Arleigh J.; Gerlach, S. Craig; Duffy, Lawrence K.

    2011-10-01

    Before adopting modern corn-and-grain-based western processed diets, circumpolar people had a high fat and protein subsistence diet and exhibited a low incidence of obesity, diabetes and cardiovascular disease. Some health benefits are attributable to a subsistence diet that is rich in omega-3 fatty acids and antioxidants. Pollution, both global and local, is a threat to wild foods, as it introduces contaminants into the food system. Northern indigenous people and their sled dogs are exposed to a variety of contaminants, including mercury, that accumulate in the fish and game that they consume. The sled dogs in Alaskan villages are maintained on the same subsistence foods as their human counterparts, primarily salmon, and therefore they can be used as a food systems model for researching the impact of changes in dietary components. In this study, the antioxidant status and mercury levels were measured for village sled dogs along the Yukon River. A reference kennel, maintained on a nutritionally balanced commercial diet, was also measured for comparison. Total antioxidant status was inversely correlated with the external stressor mercury.

  17. Lidar-based biomass assessment for the Yukon River Basin

    NASA Astrophysics Data System (ADS)

    Peterson, B.; Wylie, B. K.; Stoker, J.; Nossov, D.

    2010-12-01

    Climate change is expected to have a significant impact on high-latitude forests in terms of their ability to sequester carbon as expressed as pools of standing total biomass and soil organic matter. Above ground biomass is an important driver in ecosystem process models used to assess, predict, and understand climate change impacts. Therefore, it is of compelling interest to acquire accurate assessments of current biomass levels for these high-latitude forests, a particular challenge because of their vastness and remoteness. At this time, remote sensing is the only feasible method through which to acquire such assessments. In this study, the use of lidar data for estimating shrub and tree biomass for the Yukon Flats region of Alaska’s Yukon River Basin (YRB) is demonstrated. The lidar data were acquired in the late summer and fall of 2009 as were an initial set of field sampling data collected for training and validation purposes. The 2009 field campaigns were located near Canvasback Lake and Boot Lake in the YRB. Various tallies of biomass were calculated from the field data using allometric equations (Bond-Lamberty et al. 2002, Yarie et al. 2007, Mack et al. 2008). Additional field data were also collected during two 2010 field campaigns at different locations in the Yukon Flats. Linear regressions have been developed based on field-based shrub and tree biomass and various lidar metrics of canopy height calculated for the plots (900 m^2). A multiple linear regression performed at the plot level resulted in a strong relationship (R^2=0.88) between observed and predicted biomass at the plot level. The coefficients for this regression were used to generate a shrub and tree biomass map for the entire Yukon Flats study area covered by lidar. This biomass map will be evaluated using additional field data collected in 2010 as well as other remote sensing data sources. Furthermore, additional lidar metrics (e.g. height of median energy) are being derived from the raw

  18. Climate-driven effects of fire on winter habitat for caribou in the Alaskan-Yukon Arctic

    USGS Publications Warehouse

    Gustine, David D.; Brinkman, Todd J.; Lindgren, Michael A.; Schmidt, Jennifer I.; Rupp, T. Scott; Adams, Layne G.

    2014-01-01

    Climatic warming has direct implications for fire-dominated disturbance patterns in northern ecosystems. A transforming wildfire regime is altering plant composition and successional patterns, thus affecting the distribution and potentially the abundance of large herbivores. Caribou (Rangifer tarandus) are an important subsistence resource for communities throughout the north and a species that depends on terrestrial lichen in late-successional forests and tundra systems. Projected increases in area burned and reductions in stand ages may reduce lichen availability within caribou winter ranges. Sufficient reductions in lichen abundance could alter the capacity of these areas to support caribou populations. To assess the potential role of a changing fire regime on winter habitat for caribou, we used a simulation modeling platform, two global circulation models (GCMs), and a moderate emissions scenario to project annual fire characteristics and the resulting abundance of lichen-producing vegetation types (i.e., spruce forests and tundra >60 years old) across a modeling domain that encompassed the winter ranges of the Central Arctic and Porcupine caribou herds in the Alaskan-Yukon Arctic. Fires were less numerous and smaller in tundra compared to spruce habitats throughout the 90-year projection for both GCMs. Given the more likely climate trajectory, we projected that the Porcupine caribou herd, which winters primarily in the boreal forest, could be expected to experience a greater reduction in lichen-producing winter habitats (−21%) than the Central Arctic herd that wintered primarily in the arctic tundra (−11%). Our results suggest that caribou herds wintering in boreal forest will undergo fire-driven reductions in lichen-producing habitats that will, at a minimum, alter their distribution. Range shifts of caribou resulting from fire-driven changes to winter habitat may diminish access to caribou for rural communities that reside in fire-prone areas.

  19. Climate-Driven Effects of Fire on Winter Habitat for Caribou in the Alaskan-Yukon Arctic

    PubMed Central

    Gustine, David D.; Brinkman, Todd J.; Lindgren, Michael A.; Schmidt, Jennifer I.; Rupp, T. Scott; Adams, Layne G.

    2014-01-01

    Climatic warming has direct implications for fire-dominated disturbance patterns in northern ecosystems. A transforming wildfire regime is altering plant composition and successional patterns, thus affecting the distribution and potentially the abundance of large herbivores. Caribou (Rangifer tarandus) are an important subsistence resource for communities throughout the north and a species that depends on terrestrial lichen in late-successional forests and tundra systems. Projected increases in area burned and reductions in stand ages may reduce lichen availability within caribou winter ranges. Sufficient reductions in lichen abundance could alter the capacity of these areas to support caribou populations. To assess the potential role of a changing fire regime on winter habitat for caribou, we used a simulation modeling platform, two global circulation models (GCMs), and a moderate emissions scenario to project annual fire characteristics and the resulting abundance of lichen-producing vegetation types (i.e., spruce forests and tundra >60 years old) across a modeling domain that encompassed the winter ranges of the Central Arctic and Porcupine caribou herds in the Alaskan-Yukon Arctic. Fires were less numerous and smaller in tundra compared to spruce habitats throughout the 90-year projection for both GCMs. Given the more likely climate trajectory, we projected that the Porcupine caribou herd, which winters primarily in the boreal forest, could be expected to experience a greater reduction in lichen-producing winter habitats (−21%) than the Central Arctic herd that wintered primarily in the arctic tundra (−11%). Our results suggest that caribou herds wintering in boreal forest will undergo fire-driven reductions in lichen-producing habitats that will, at a minimum, alter their distribution. Range shifts of caribou resulting from fire-driven changes to winter habitat may diminish access to caribou for rural communities that reside in fire-prone areas. PMID

  20. Geochemistry of yukon and copper river tributaries, Alaska

    USGS Publications Warehouse

    Carney, M.; Ellis, A.; Bullen, T.; Langman, J.

    2009-01-01

    Alaska is already beginning to be affected by changes in global climate which make it a good location to study the feedback effects between climate, the water cycle and the carbon cycle. Using river dissolved elements and Sr isotopes we examine changes and/or differences in chemical weathering between watersheds in predominantly permafrost areas and glacial watersheds. Tributaries of the Tanana, Yukon, Nenana and Copper rivers were sampled during the early snow melt in late May and the late permafrost/glacial melt period in September of 2007. Waters are predominantly CaHCO3-/SO4 which is typical of glaciated terrains. 87Sr/86Sr isotopes indicate three potential end-members, young basalts, radiogenic silicates and marine carbonates. The results are consistent with weathering observed in glaciated regions with trace calcites and salts dominating the dissolved load; however we have evidence for silicate weathering. Results also indicate that permafrost watersheds experience more progressive silicate weathering than glacial watersheds. ??2009 ASCE.

  1. Annual estimates of water and solute export from 42 tributaries to the Yukon River

    USGS Publications Warehouse

    Frederick Zanden; Suzanne P. Anderson; Striegl, Rob

    2012-01-01

    Annual export of 11 major and trace solutes for the Yukon River is found to be accurately determined based on summing 42 tributary contributions. These findings provide the first published estimates of tributary specific distribution of solutes within the Yukon River basin. First, we show that annual discharge of the Yukon River can be computed by summing calculated annual discharges from 42 tributaries. Annual discharge for the tributaries is calculated from the basin area and average annual precipitation over that area using a previously published regional regression equation. Based on tributary inputs, we estimate an average annual discharge for the Yukon River of 210 km3 year–1. This value is within 1% of the average measured annual discharge at the U.S. Geological Survey gaging station near the river terminus at Pilot Station, AK, for water years 2001 through 2005. Next, annual loads for 11 solutes are determined by combining annual discharge with point measurements of solute concentrations in tributary river water. Based on the sum of solutes in tributary water, we find that the Yukon River discharges approximately 33 million metric tons of dissolved solids each year at Pilot Station. Discharged solutes are dominated by cations calcium and magnesium (5.65 × 109 and 1.42 × 109 g year–1) and anions bicarbonate and sulphate (17.3 × 109 and 5.40 × 109 g year–1). These loads compare well with loads calculated independently at the three continuous gaging stations along the Yukon River. These findings show how annual solute yields vary throughout a major subarctic river basin and that accurate estimates of total river export can be determined from calculated tributary contributions.

  2. Large Quantities of Melt-Quenched Impact Spherules in Late Pleistocene Alaskan and Yukon "Muck" Deposits

    NASA Astrophysics Data System (ADS)

    Hagstrum, J. T.; Firestone, R. B.; West, A.; Weaver, J. C.; Bunch, T. E.; Kimbel, D. R.

    2012-12-01

    The so-called "muck" deposits of Alaska and the upper Yukon are wind-transported, silt-dominated, organic-rich sediments, including paleosols, erosional unconformities, and buried forests with in situ stumps, that have accumulated in creek valleys over at least the last 2 million years. Underlying the frozen muck are gold-bearing gravels, and removal of Late Pleistocene muck layers in mining operations has uncovered a remarkable collection of usually broken and disarticulated megafaunal bones and carcasses. Previously, Fe-rich particles have been found embedded in a number of mammoth tusks and a bison skull, and those particles have high-Ni and low-Ti compositions indicative of an extraterrestrial origin. These fossils range in age from ~21 to 37 ka B.P. Additional fossil skulls (bison, rangifer, mammoth) and a mammoth tusk from Alaska and the Yukon Territory have been found in museum and government collections with embedded Fe-rich particles as well, and nine skulls also contain significant quantities of original host sediment within them. This associated sediment was removed and examined for the presence of spherules and other cosmic impact proxies. The additional megafaunal bones are estimated to date from between 13 to 40 ka, and radiocarbon dating of samples from these specimens is currently underway. Magnetic grains were extracted from aliquots of bulk sediment from each of the fossil skulls. The magnetic fractions ranged from ~5 to 44 g/kg, averaging 23.6 g/kg. We then examined each sample fraction for magnetic spherules. Two samples contained rounded detrital magnetite and no spherules, while the other seven samples contained numerous melt-quenched magnetic spherules ranging in abundance from ~1000 to 18,000/kg, averaging ~8000/kg. We performed SEM-EDS analyses on 49 selected spherules and identified two distinct compositional populations. One group from a mammoth skull is predominately aluminosilicate (Al2O3 = 30.7 wt.%, SiO2 = 34.4 wt.%, FeO = 23.4 wt

  3. Alaska and Yukon Fires

    Atmospheric Science Data Center

    2014-05-15

    article title:  Smoke Signals from the Alaska and Yukon Fires   ... the Yukon Territory from mid-June to mid-July, 2004. Thick smoke particles filled the air during these fires, prompting Alaskan officials to issue air quality warnings. Some of the smoke from these fires was detected as far away as New Hampshire. These ...

  4. Age of Volcanism of the Wolverine Volcanic Center, West-Central Yukon Territory, Canada and its Implications for the History of Yukon River

    NASA Astrophysics Data System (ADS)

    Jackson, L. E.; Huscroft, C. A.; Ward, B. C.; Villeneuve, M.

    2008-12-01

    New Ar-Ar ages determined on the Wolverine Creek volcanic center (WC) establishes a middle Pliocene initiation of volcanism for the Fort Selkirk Volcanic Group (FSVG), Fort Selkirk area, west-central Yukon, Canada. WC was active between 4.34±0.06 and 2.98±0.05 Ma. Lava flows repeatedly descended Wolverine Creek valley and flowed into the Yukon River Valley (YRV) during the eruptive life of WC. The total thickness of WC lava flows in YRV decreases in a northward direction and the overall elevation of the surface of the highest flow at any point descends northward as well. Total thickness is up to 100 m in the canyon of Wolverine Creek with a surface elevation of approximately 550 m a.s.l. WC lava flows extend to the confluence of Yukon River with Pelly River 7 km north of the Wolverine Creek confluence with YRV. The lava fill has a total thickness of about 80 m at this northern limit with a surface elevation of 520 m a.s.l. The youngest flow there is dated at 3.05±0.07 Ma. The flows in this area show a general upward compositional change from basanite to alkali olivine basalt which is characteristic of WC. The thinning of the flows and decrease in elevation in a northward direction in YRV is consistent with the contemporary flow direction of Yukon River. Furthermore, the WC flows presumably extended farther down YRV (north and west) prior to erosional truncation. In contrast, lava flows are absent south (up contemporary flow of Yukon River) from the confluence of Wolverine Creek with YRV. This is consistent with the pattern of quenching that would be expected for any lava flow that enters YRV from Wolverine Creek and encounters a north-flowing Yukon River. This pattern is similar to those of lava flows from the younger Pelly and Black Creek FSVG eruptive centers immediately downstream of the Yukon River-Pelly River confluence. Similar asymmetries in lava flows that entered river canyons have been reported by others in the western Grand Canyon and for the 200 year

  5. A Yukon River Basin Landsat Mosaic for Assessing Environmental Change

    NASA Astrophysics Data System (ADS)

    Bouchard, M. A.; Dwyer, J. L.; Granneman, B.

    2009-12-01

    Landsat data from the Global Land Survey (GLS) dataset for year 2000 was mosaicked to form a Yukon River Basin image map that is referenced to a geodetic base. It was produced from 66 Landsat-7 Enhanced Thematic Mapper Plus (ETM+) images collected from 1999-2002. Two products were created: (1) a geographically referenced database containing all seven of the spectral bands for the individual scenes and (2) a 3-band (shortwave infrared, near-infrared, and green - 7,4,2) radiometrically normalized shaded relief image map using the U.S. Geological Survey National Elevation Dataset and Canadian Digital Elevation Data from Natural Resources Canada. The science data product will facilitate studies to map the extent of snow, ice and surface water at a basin-wide scale. Focused studies on snow/ice transitions for selected glaciers will be conducted in order to establish accumulation ratios for use in future monitoring. The mosaic also shows the complex patterns of wildfires in the interior forests and the diversity of ecosystems throughout the basin. The shaded relief product image mosaic is a reference map for reconnaissance studies as well as a geographic framework within which to spatially integrate project-wide data and information.

  6. Preliminary Findings From the First Year of the USGS Yukon River NASQAN Study

    NASA Astrophysics Data System (ADS)

    Brabets, T. P.

    2002-12-01

    The Yukon River, located in northwestern Canada and central Alaska, drains an area of more than 330,000 square miles, making it the fourth largest drainage basin in North America. The Yukon River is being studied from 2001 to 2005 as part of the U.S. Geological Survey's National Stream Quality Accounting Network (NASQAN) program. A number of constituents are being measured during this study and include sediment, major ions, trace elements and nutrients, dissolved and particulate carbon, and mercury. Five water-quality sites have been established in the basin. Three are located along the main stem of the Yukon River: at Eagle, near Stevens Village, and at Pilot Station; and two at major tributaries - the Tanana River, and the Porcupine River. Data from the first year of the study (October 2000 to September 2001) indicate large differences between the Tanana and Porcupine Rivers. Both basins are approximately the same size, 25,600 square miles and 29,500 square miles respectively, but glaciers cover about 6 percent of the Tanana River Basin whereas the Porcupine River Basin contains no glaciers but is underlain by permafrost. Runoff from the Tanana River Basin was 13.8 inches while runoff from the Porcupine River Basin was 7.8 inches. Approximately 25 million tons of suspended sediment were transported by the Tanana River while approximately 3 million tons of suspended sediment were transported by the Porcupine River. Suspended sediment loads transported past the Yukon River gages at Eagle (near the Canada-U.S. border), near Stevens Village, and Pilot Station (near the mouth) were 44, 52, and 89 million tons respectively. These suspended sediment loads suggest that the Yukon Flats area (located between Eagle and Steven Village) may not be a depositional area for sediment. At all sites, concentrations of nitrogen are less than 1.0 mg/L although phosphorus concentrations are greater than 0.1 mg/L. Dissolved organic carbon concentrations peak at the beginning of the

  7. Ecology of invasive Melilotus albus on Alaskan glacial river floodplains

    USGS Publications Warehouse

    Conn, Jeff S.; Werdin-Pfisterer, Nancy R.; Beattie, Katherine L.; Densmore, Roseann V.

    2011-01-01

    Melilotus albus (white sweetclover) has invaded Alaskan glacial river floodplains. We measured cover and density of plant species and environmental variables along transects perpendicular to the Nenana, Matanuska, and Stikine Rivers to study interactions between M. albus and other plant species and to characterize the environment where it establishes. Melilotus albus was a pioneer species on recently disturbed sites and did not persist into closed canopy forests. The relationships between M. albus cover and density and other species were site-specific.Melilotus albus was negatively correlated with native species Elaeagnus commutata at the Nenana River, but not at the Matanuska River. Melilotus albus was positively correlated with the exotic species Crepis tectorumand Taraxacum officinale at the Matanuska River and T. officinale on the upper Stikine River. However, the high density of M. albus at a lower Stikine River site was negatively correlated with T. officinale and several native species including Lathyrus japonicus var. maritimus and Salix alaxensis. Glacial river floodplains in Alaska are highly disturbed and are corridors for exotic plant species movement. Melilotus albus at moderate to low densities may facilitate establishment of exotic species, but at high densities can reduce the cover and density of both exotic and native species.

  8. Differences in Ichthyophonus prevalence and infection severity between upper Yukon River and Tanana River chinook salmon, Oncorhynchus tshawytscha (Walbaum), stocks

    USGS Publications Warehouse

    Kocan, R.; Hershberger, P.

    2006-01-01

    Two genetically distinct populations of chinook salmon, Oncorhynchus tshawytscha (Walbaum), were simultaneously sampled at the confluence of the Yukon and Tanana rivers in 2003. Upper Yukon-Canadian fish had significantly higher infection prevalence as well as more severe infections (higher parasite density in heart tissue) than the lower Yukon-Tanana River fish. Both populations had migrated the same distance from the mouth of the Yukon River at the time of sampling but had significantly different distances remaining to swim before reaching their respective spawning grounds. Multiple working hypotheses are proposed to explain the differences between the two stocks: (1) the two genetically distinct populations have different inherent resistance to infection, (2) genetically influenced differences in feeding behaviour resulted in temporal and/or spatial differences in exposure, (3) physiological differences resulting from different degrees of sexual maturity influenced the course of disease, and (4) the most severely infected Tanana River fish either died en route or fatigued and were unable to complete their migration to the Tanana River, thus leaving a population of apparently healthier fish. ?? 2006 Blackwell Publishing Ltd.

  9. Studies of Climate Change in the Yukon River Basin: Connecting Community and Science Through a Unique Partnership

    USGS Publications Warehouse

    Schuster, Paul F.; Maracle, Karonhiakta'tie Byran

    2010-01-01

    An exciting new partnership between the U.S. Geological Survey (USGS) and the Yukon River Inter-Tribal Watershed Council (YRITWC) is yielding critical data for the assessment of climate change effects in the Yukon River Basin. The foundation of this partnership is a shared interest in the current and future water quality of the Yukon River and its relation to climate. The USGS began a landmark study of the Yukon River and its major tributaries in 2000. A key objective of this study is to establish a baseline dataset of water quality, which will serve as an important frame of reference to assess future changes in the basin that may result from a warmer climate.

  10. Baseline values of Polycyclic Aromatic Hydrocarbons and Trace Metals in the Yukon River, Alaska

    NASA Astrophysics Data System (ADS)

    Perreault, J.; McCarthy, P.

    2014-12-01

    The Yukon River drains an area of more than 800 km2 across Canada and Alaska. Sediments are deposited along the western coast of Alaska in the Bering and Chukchi Seas, and represent most of the sediment deposited in the Chukchi Sea. Suspended sediments, bed load sediments, and historical cores were collected from the last non-marine influenced stretch of the Yukon River and analyzed for the presence and quantity of trace metals, organic carbon, and polycyclic aromatic hydrocarbons (PAH). C14 dates from cores sampled from the delta region and intra-annual active river sampling from 2012-2013, show an annual flux of these materials within the context of a historical comparison. Grain size distributions of tested contaminants suggest contributions to the Chukchi Sea sediment budget.

  11. Pleistocene vertebrates of the Yukon Territory

    NASA Astrophysics Data System (ADS)

    Harington, C. R.

    2011-08-01

    Unglaciated parts of the Yukon constitute one of the most important areas in North America for yielding Pleistocene vertebrate fossils. Nearly 30 vertebrate faunal localities are reviewed spanning a period of about 1.6 Ma (million years ago) to the close of the Pleistocene some 10 000 BP (radiocarbon years before present, taken as 1950). The vertebrate fossils represent at least 8 species of fishes, 1 amphibian, 41 species of birds and 83 species of mammals. Dominant among the large mammals are: steppe bison ( Bison priscus), horse ( Equus sp.), woolly mammoth ( Mammuthus primigenius), and caribou ( Rangifer tarandus) - signature species of the Mammoth Steppe fauna ( Fig. 1), which was widespread from the British Isles, through northern Europe, and Siberia to Alaska, Yukon and adjacent Northwest Territories. The Yukon faunas extend from Herschel Island in the north to Revenue Creek in the south and from the Alaskan border in the west to Ketza River in the east. The Yukon holds evidence of the earliest-known people in North America. Artifacts made from bison, mammoth and caribou bones from Bluefish Caves, Old Crow Basin and Dawson City areas show that people had a substantial knowledge of making and using bone tools at least by 25 000 BP, and possibly as early as 40 000 BP. A suggested chronological sequence of Yukon Pleistocene vertebrates ( Table 1) facilitates comparison of selected faunas and indicates the known duration of various taxa.

  12. Quantitative mineralogy of the Yukon River system: Changes with reach and season, and determining sediment provenance

    USGS Publications Warehouse

    Eberl, D.D.

    2004-01-01

    The mineralogy of Yukon River basin sediment has been studied by quantitative X-ray diffraction. Bed, beach, bar, and suspended sediments were analyzed using the RockJock computer program. The bed sediments were collected from the main stem and from selected tributaries during a single trip down river, from Whitehorse to the Yukon River delta, during the summer of 2001. Beach and bar sediments were collected from the confluence region of the Tanana and Yukon Rivers during the summer of 2003. Suspended sediments were collected at three stations on the Yukon River and from a single station on the Tanana River at various times during the summers of 2001 through 2003, with the most complete set of samples collected during the summer of 2002. Changes in mineralogy of Yukon River bed sediments are related to sediment dilution or concentration effects from tributary sediment and to chemical weathering during transport. Carbonate minerals compose about 2 wt% of the bed sediments near Whitehorse, but increase to 14 wt% with the entry of the White River tributary above Dawson. Thereafter, the proportion of carbonate minerals decreases downstream to values of about 1 to 7 wt% near the mouth of the Yukon River. Quartz and feldspar contents of bed sediments vary greatly with the introduction of Pelly River and White River sediments, but thereafter either increase irregularly (quartz from 20 to about 50 wt%) or remain relatively constant (feldspar at about 35 wt%) with distance downstream. Clay mineral content increases irregularly downstream from about 15 to about 30 wt%. The chief clay mineral is chlorite, followed by illite + smectite; there is little to no kaolinite. The total organic carbon content of the bed sediments remains relatively constant with distance for the main stem (generally 1 to 2 wt%, with one exception), but fluctuates for the tributaries (1 to 6 wt%). The mineralogies of the suspended sediments and sediment flow data were used to calculate the amount of

  13. Influences of glacial melt and permafrost thaw on the age of dissolved organic carbon in the Yukon River basin

    USGS Publications Warehouse

    Aiken, George R.; Robert Spencer; Striegl, Rob; Schuster, Paul F.; Peter Raymond

    2016-01-01

    Responses of near-surface permafrost and glacial ice to climate change are of particular significance for understanding long-term effects on global carbon cycling and carbon export by high-latitude northern rivers. Here we report Δ14C-dissolved organic carbon (DOC) values and dissolved organic matter optical data for the Yukon River, 15 tributaries of the Yukon River, glacial meltwater, and groundwater and soil water end-member sources draining to the Yukon River, with the goal of assessing mobilization of aged DOC within the watershed. Ancient DOC was associated with glacial meltwater and groundwater sources. In contrast, DOC from watersheds dominated by peat soils and underlain by permafrost was typically enriched in Δ14C indicating that degradation of ancient carbon stores is currently not occurring at large enough scales to quantitatively influence bulk DOC exports from those landscapes. On an annual basis, DOC exported was predominantly modern during the spring period throughout the Yukon River basin and became older through summer-fall and winter periods, suggesting that contributions of older DOC from soils, glacial meltwaters, and groundwater are significant during these months. Our data indicate that rapidly receding glaciers and increasing groundwater inputs will likely result in greater contributions of older DOC in the Yukon River and its tributaries in coming decades.  

  14. The plume of the Yukon River in relation to the oceanography of the Bering Sea

    NASA Technical Reports Server (NTRS)

    Dean, Kenneson G.; Mcroy, C. Peter; Ahlnas, Kristina; Springer, Alan

    1989-01-01

    The ecosystem of the northern Bering-Sea shelf was studied using data from the NOAA Very High Resolution Radiometer and AVHRR and the Landsat MSS and Thematic Mapper (TM) in conjunction with shipboard measurements. Emphasis was placed on the influence of the Yukon River on this inner shelf environment and on the evaluation of the utility of the new Landsat TM data for oceanography. It was found that the patterns of water mass distribution obtained from satellite images agreed reasonably well with the areal patterns of temperature, salinity, and phytoplankton distributions. The AVHRR, MSS, and TM data show that the Yukon-River discharge is warmer and more turbid than the surrounding coastal water that originates to the south; thus, the Yukon water contributes to the higher temperatures and lower transmissivity of the coastal water. The high resolution of the TM thermal IR band made it possible to observe complex patterns and structures in the surface water that could not be resolved on previous data sets.

  15. Seasonal Variability and Chemical Composition of Carbon Export by the Yukon River, Alaska

    NASA Astrophysics Data System (ADS)

    Striegl, R.; Aiken, G.; Butman, D.; Dornblaser, M.; Raymond, P.; Schuster, P.; Spencer, R.; Stubbins, A.; Wickland, K.

    2012-04-01

    The flow and chemical composition of Arctic rivers are highly variable and reflect the mix of sources and flow paths of surface and ground water contributing to them during any particular season. Annual Yukon River carbon (C) export is dominated by the spring flush, with more than 50% of organic C and 30% of inorganic C exports occurring during May and June. As part of the US National Science Foundation's Arctic Great Rivers Observatory Project, which is studying the six largest rivers discharging to the Arctic Ocean, we measured Yukon River flow and water chemistry at high frequency during the critical periods immediately preceding, during, and following ice melt in 2009 - 2011. Springtime flows had high dissolved organic carbon (DOC) concentrations that rose quickly with water discharge at ice out and decreased with flow into summer. Waters collected near peak flow had high specific ultraviolet absorbance (SUVA) values and high aromatic C content. The rising limb of the spring flush hydrograph also had the greatest bioavailable DOC (BDOC) content, relative to the remainder of the year. The bulk of the DOC exported in spring was of terrestrial plant origin and 14C modern, with respiration carbon dioxide collected from BDOC incubations having similar 14C content to that of the bulk DOC. Interestingly, FT-ICR MS characterization of the DOC exported during the spring flush indicated the presence of labile, atmospherically deposited DOC components having apparent fossil fuel combustion origin, similar to those identified in direct glacial runoff. The importance of the spring flush period and of DOC exports to the total C budget of the Yukon River will also be discussed in the context of seasonal patterns of water discharge, watershed C yields, and of dissolved, particulate, and gaseous inorganic and organic C concentration and flux.

  16. Estimating aboveground biomass in the boreal forests of the Yukon River Basin, Alaska

    NASA Astrophysics Data System (ADS)

    Ji, L.; Wylie, B. K.; Nossov, D.; Peterson, B.; Waldrop, M. P.; McFarland, J.; Alexander, H. D.; Mack, M. C.; Rover, J. A.; Chen, X.

    2011-12-01

    Quantification of aboveground biomass (AGB) in Alaska's boreal forests is essential to accurately evaluate terrestrial carbon stocks and dynamics in northern high-latitude ecosystems. However, regional AGB datasets with spatially detailed information (<500 m) are not available for this extensive and remote area. Our goal was to map AGB at 30-m resolution for the boreal forests in the Yukon River Basin of Alaska using recent Landsat data and ground measurements. We collected field data in the Yukon River Basin from 2008 to 2010. Ground measurements included diameter at breast height (DBH) or basal diameter (BD) for live and dead trees and shrubs (>1 m tall), which were converted to plot-level AGB using allometric equations. We acquired Landsat Enhanced Thematic Mapper Plus (ETM+) images from the Web Enabled Landsat Data (WELD) that provides multi-date composites of top-of-atmosphere reflectance and brightness temperature for Alaska. From the WELD images, we generated a three-year (2008 - 2010) image composite for the Yukon River Basin using a series of compositing criteria including non-saturation, non-cloudiness, maximal normalize difference vegetation index (NDVI), and maximal brightness temperature. Airborne lidar datasets were acquired for two sub-regions in the central basin in 2009, which were converted to vegetation height datasets using the bare-earth digital surface model (DSM) and the first-return DSM. We created a multiple regression model in which the response variable was the field-observed AGB and the predictor variables were Landsat-derived reflectance, brightness temperature, and spectral vegetation indices including NDVI, soil adjusted vegetation index (SAVI), enhanced vegetation index (EVI), normalized difference infrared index (NDII), and normalized difference water index (NDWI). Principal component analysis was incorporated in the regression model to remedy the multicollinearity problems caused by high correlations between predictor variables

  17. Strategic needs of water on the Yukon: an interdisciplinary approach to studying hydrology and climate change in the Lower Yukon River Basin

    USGS Publications Warehouse

    Herman-Mercer, Nicole M.; Schuster, Paul F.

    2014-01-01

    Strategic Needs of Water on the Yukon (SNOWY) is an interdisciplinary research project funded by the National Science Foundation (NSF; http://www.nsf.gov/). The SNOWY team is made up of a diverse group of researchers from different backgrounds and organizations. This partnership between scientists from different disciplines (hydrology, geography, and social science), government agencies, nonprofit organizations, universities, and Lower Yukon River Basin (LYRB) and Yukon-Kuskokwim (YK) Delta communities provided an opportunity to study the effects of climate change using a holistic approach. The Arctic and Subarctic are experiencing environmental change at a rate faster than the rest of the world, and the lack of historical baseline data in these often remote locations makes understanding and predicting regional climate change difficult. This project focused on collecting data to fill in these gaps by using both quantitative and qualitative methodologies to tell the story of environmental change in this region as told by the physical data and the people who rely on this landscape.

  18. Suspended sediment and carbonate transport in the Yukon River Basin, Alaska: Fluxes and potential future responses to climate change

    USGS Publications Warehouse

    Dornblaser, M.M.; Striegl, R.G.

    2009-01-01

    Loads and yields of suspended sediment and carbonate were measured and modeled at three locations on the Yukon, Tanana, and Porcupine Rivers in Alaska during water years 2001-2005 (1 October 2000 to 30 September 2005). Annual export of suspended sediment and carbonate upstream from the Yukon Delta averaged 68 Mt a-1 and 387 Gg a-1, respectively, with 50% of the suspended sediment load originating in the Tanana River Basin and 88% of the carbonate load originating in the White River Basin. About half the annual suspended sediment export occurred during spring, and half occurred during summer-autumn, with very little export in winter. On average, a minimum of 11 Mt a-1 of suspended sediment is deposited in floodplains between Eagle, Alaska, and Pilot Station, Alaska, on an annual basis, mostly in the Yukon Flats. There is about a 27% loss in the carbonate load between Eagle and Yukon River near Stevens Village, with an additional loss of about 29% between Stevens Village and Pilot Station, owing to a combination of deposition and dissolution. Comparison of current and historical suspended sediment loads for Tanana River suggests a possible link between suspended sediment yield and the Pacific decadal oscillation.

  19. A decrease in discharge-normalized DOC export by the Yukon River during summer through autumn

    USGS Publications Warehouse

    Striegl, R.G.; Aiken, G.R.; Dornblaser, M.M.; Raymond, P.A.; Wickland, K.P.

    2005-01-01

    Climate warming is having a dramatic effect on the vegetation distribution and carbon cycling of terrestrial subarctic and arctic ecosystems. Here, we present hydrologic evidence that warming is also affecting the export of dissolved organic carbon and bicarbonate (DOC and HCO3-) at the large basin scale. In the 831,400 km2 Yukon River basin, water discharge (Q) corrected DOC export significantly decreased during the growing season from 1978-80 to 2001-03, indicating a major shift in terrestrial to aquatic C transfer. We conclude that decreased DOC export, relative to total summer through autumn Q, results from increased flow path, residence time, and microbial mineralization of DOC in the soil active layer and groundwater. Counter to current predictions, we argue that continued warming could result in decreased DOC export to the Bering Sea and Arctic Ocean by major subarctic and arctic rivers, due to increased respiration of organic C on land. Copyright 2005 by the American Geophysical Union.

  20. Biomonitoring of Environmental Status and Trends (BEST) Program: Environmental Contaminants and Their Effects on Fish in the Yukon River Basin

    USGS Publications Warehouse

    Hinck, Jo Ellen; Bartish, Timothy M.; Blazer, Vicki; Denslow, Nancy D.; Gross, Tim S.; Myers, Mark S.; Anderson, Patrick J.; Orazio, Carl E.; Tillitt, Donald E.

    2004-01-01

    This project collected, examined, and analyzed 217 fish representing three species at 10 stations in the U.S. portion of the Yukon River Basin (YRB) from May to October 2002. Four sampling sites were located on the Yukon River; two were located on the Porcupine River, and one site was on each of the Ray, Tanana, Tolavana, and Innoko Rivers. Norther pike (Esox lucius), longnose sucker (Catostomus catostomus), and burbot (Lota lota) were weighed and measured, and examined in the field for external and internal lesions, and liver, spleen, and gonads were weighed to compute somatic indices. Selected tissues and fluids were collected and preserved for analysis of fish health and reproductive biomarkers. Composite samples of whole fish from each station were grouped by species and gender and analyzed for organochlorines and elemental contaminants and for dioxin-like activity using H4IIE rat hepatoma cell bioassay.

  1. Biodegradability of dissolved organic carbon in the Yukon River and its tributaries: Seasonality and importance of inorganic nitrogen

    USGS Publications Warehouse

    Wickland, Kimberly P.; Aiken, George R.; Butler, Kenna; Dornblaser, Mark M.; RGM Spencer; Striegl, Rob

    2012-01-01

    Northern high-latitude rivers transport large amounts of terrestrially derived dissolved organic matter (DOM) from boreal and arctic ecosystems to coastal areas and oceans. Current knowledge of the biodegradability of DOM in these rivers is limited, particularly for large rivers discharging to the Arctic Ocean. We conducted a seasonally comprehensive study of biodegradable dissolved organic carbon (BDOC) dynamics in the Yukon River and two of its tributaries in Alaska, USA. Distinct seasonal patterns of BDOC, consistent across a wide range of watershed size, indicate BDOC is transported year-round. Relative biodegradability (%BDOC) was greatest during winter, and decreased into spring and summer. Due to large seasonal differences in DOC concentration, the greatest concentrations of BDOC (mg C L−1) occurred during spring freshet, followed by winter and summer. While chemical composition of DOM was an important driver of BDOC, the overriding control of BDOC was mineral nutrient availability due to wide shifts in carbon (C) and nitrogen (N) stoichiometry across seasons. We calculated seasonal and annual loads of BDOC exported by the Yukon River by applying measured BDOC concentrations to daily water discharge values, and also by applying an empirical correlation between %BDOC and the ratio of DOC to dissolved inorganic N (DIN) to total DOC loads. The Yukon River exports ∼0.2 Tg C yr−1 as BDOC that is decomposable within 28 days. This corresponds to 12–18% of the total annual DOC export. Furthermore, we calculate that the six largest arctic rivers, including the Yukon River, collectively export ∼2.3 Tg C yr−1 as BDOC to the Arctic Ocean.

  2. Environmental contaminants in fish and their associated risk to piscivorous wildlife in the Yukon River Basin, Alaska.

    PubMed

    Hinck, Jo Ellen; Schmitt, Christopher J; Echols, Kathy R; May, Tom W; Orazio, Carl E; Tillitt, Donald E

    2006-11-01

    Organochlorine chemical residues and elemental contaminants were measured in northern pike (Esox lucius), longnose sucker (Catostomus catostomus), and burbot (Lota lota) from 10 sites in the Yukon River Basin (YRB) during 2002. Contaminant concentrations were compared to historical YRB data and to toxicity thresholds for fish and piscivorous wildlife from the scientific literature. A risk analysis was conducted to screen for potential hazards to piscivorous wildlife for contaminants that exceeded literature-based toxicity thresholds. Concentrations of total DDT (sum of p,p'-homologs; 1.09-13.6 ng/g), total chlordane (0.67-7.5 ng/g), dieldrin (<0.16-0.6 ng/g), toxaphene (<11-34 ng/g), total PCBs (<20-87 ng/g), TCDD-EQ (Alaskan fish and wildlife. PMID:17009129

  3. Airborne Imaging in the Yukon River Basin to Characterize SWOT Mission Phenomenology

    NASA Astrophysics Data System (ADS)

    Moller, D.; Pavelsky, T.; Arvesen, J. C.

    2015-12-01

    Remote sensing offers intriguing tools to track Arctic hydrology, but current techniques are largely limited to tracking either inundation or water surface elevation only. For the first time, the proposed Surface Water Ocean Topography (SWOT) satellite mission will provide regular, simultaneous observations of inundation extent and water level from space. SWOT is unique and distinct from precursor altimetry missions in some notable regards: 1) 100km+ of swath will provide complete ocean coverage, 2) in addition to the ocean product, land surface water will be mapped for storage measurement and discharge estimation and 3) Ka-band single-pass interferometry will produce the height measurements introducing a new measurement technique. This new approach introduces additional algorithmic, characterization and calibration/validation needs for which the Ka-band SWOT Phenomenology Airborne Radar (KaSPAR) was developed. In May 2015, AirSWOT (comprised of KaSPAR and a color infrared (CIR) high resolution aerial camera) was part of an intensive field campaign including observations of inundation extent and water level and in situ hydrologic measurements in two rivers and 20 lakes within the Yukon River Basin, Alaska. One goal is to explore the fundamental phenomenology of the SWOT measurement. This includes assessment of the effects of vegetation layover and attenuation, wind roughening and classification. Further KaSPAR-derived inundation extent will to be validated using a combination of ground surveys and coregistered CIR imagery. Ultimately, by combining measurements of changing inundation extent and water level between two collection dates, it will be possible to validate lake water storage variations against storage changes computed from in situ water levels and inundation area derived from AirSWOT. Our paper summarizes the campaign, the airborne and in situ measurements and presents some initial KaSPAR and CIR imagery from the Yukon flats region.

  4. Synchronous cycling of Ichthyophoniasis with Chinook salmon density revealed during the annual Yukon River spawning migration

    USGS Publications Warehouse

    Zuray, Stanley; Kocan, Richard; Hershberger, Paul

    2012-01-01

    Populations of Chinook salmon Oncorhynchus tshawytscha in the Yukon River declined by more than 57% between 2003 and 2010, probably the result of a combination of anthropogenic and environmental factors. One possible contributor to this decline is Ichthyophonus, a mesomycetozoan parasite that has previously been implicated in significant losses of fish, including Chinook salmon. A multiyear epidemiological study of ichthyophoniasis in the Yukon River revealed that disease prevalence and Chinook salmon population abundance increased and decreased simultaneously (i.e., were concordant) from 1999 to 2010. The two values rose and fell synchronously 91% of the time for female Chinook salmon and 82% of the time for males; however, there was no significant correlation between Ichthyophonus prevalence and population abundance. This synchronicity might be explained by a single factor, such as a prey item that is critical to Chinook salmon survival as well as a source of Ichthyophonus infection. The host–parasite relationship between Ichthyophonus and migrating Chinook salmon from 2004 to 2010 was similar to that reported for the previous 5 years. During 2004–2010, overall disease prevalence was significantly higher among females (21%) than among males (8%), increased linearly with fish length for both males and females, and increased in both sexes as the fish progressed upriver. These regularly occurring features of host–parasite dynamics confirm a stable base of transmission for Ichthyophonus. However, from 2003 to 2010, disease prevalence decreased from 30% to just 8% in males and from 45% to 9% in females, paralleling a similar decline in Chinook salmon abundance during the same period. These findings may help clarify questions regarding the complex host–parasite dynamics that occur in marine species such as herrings Clupea spp., which have less well-defined population structures.

  5. Water and Sediment Quality in the Yukon River and its Tributaries Between Atlin, British Columbia, Canada, and Eagle, Alaska, USA, 2004

    USGS Publications Warehouse

    Halm, Douglas R.; Dornblaser, Mark M.

    2007-01-01

    The Yukon River basin is the fourth largest watershed in North America at 831,400 square kilometers (km2). Approximately 126,000 people live within the basin and depend on the Yukon River and its tributaries for drinking water, commerce, subsistence, and recreational fish and game resources. Climate warming in the Arctic and Subarctic regions encompassing the Yukon basin has recently become a concern because of possible far-reaching effects on the ecosystem. Large amounts of carbon and nutrients are stored in permafrost and have potential for release in response to this warming. These changes in carbon and nutrient cycling may result in changes in stream chemistry and productivity, including salmon populations, and ultimately changes in the chemistry and productivity of the Bearing Sea. To address these concerns, the U.S. Geological Survey (USGS) conducted a 5-year comprehensive water-quality study of the Yukon River and its major tributaries starting in 2000. The study included frequent water-quality sampling at a fixed site network as well as intensive sampling along the Yukon River and its major tributaries. This report contains observations of water and sediment quantity and quality of the Yukon River and its tributaries in Canada during 2004. Chemical, biological, physical, and discharge data are presented for the reach of river between Atlin, British Columbia, Canada, and Eagle, Alaska, USA.

  6. Impact of Ichthyophonus infection on spawning success of Yukon River Chinook salmon Oncorhynchus tshawytscha.

    PubMed

    Hamazaki, Toshihide; Kahler, Eryn; Borba, Bonnie M; Burton, Tamara

    2013-11-01

    We examined the impacts of Ichthyophonus infection on spawning success of Yukon River Chinook salmon Oncorhynchus tshawytscha at spawning grounds of the Chena and Salcha Rivers, Alaska, USA. During the period 2005 to 2006, 1281 salmon carcasses (628 male, 652 female) were collected throughout the spawning season and from the entire spawning reaches of the Chena and Salcha Rivers. For each fish, infection status was determined by culture method and visual inspection of lesions of heart tissue as uninfected (culture negative), infected without lesions (culture positive with no visible lesions), and infected with lesions (culture positive with visible lesions), and spawning status was determined by visually inspecting the percentage of gametes remaining as full-spawned (<10%), partial-spawned (10-50%), and unspawned (>50%). Among the 3 groups, the proportion of full-spawned (i.e. spawning success) females was lower for those infected without lesions (69%) than those uninfected (87%) and infected with lesions (86%), but this did not apply to males (uninfected 42%, infected without lesions 38%, infected with lesions 41%). At the population level, the combined (infected and uninfected) proportion of female spawning success was 86%, compared to 87% when all females were assumed uninfected. These data suggest that while Ichthyophonus infection slightly reduces spawning success of infected females, its impact on the spawning population as a whole appears minimal. PMID:24191998

  7. Mercury export from the Yukon River Basin and potential response to a changing climate

    USGS Publications Warehouse

    Schuster, Paul F.; Striegl, Robert G.; Aiken, George R.; Krabbenhoft, David P.; DeWild, John F.; Butler, Kenna; Kamark, Ben; Dornblaser, Mark

    2011-01-01

    We measured mercury (Hg) concentrations and calculated export and yield from the Yukon River Basin (YRB) to quantify Hg flux from a large, permafrost-dominated, high-latitude watershed. Exports of Hg averaged 4400 kg Hg yr-1. The average annual yield for the YRB during the study period was 5.17 μg m-2 yr-1, which is 3–32 times more than Hg yields reported for 8 other major northern hemisphere river basins. The vast majority (90%) of Hg export is associated with particulates. Half of the annual export of Hg occurred during the spring with about 80% of 34 samples exceeding the U.S. EPA Hg standard for adverse chronic effects to biota. Dissolved and particulate organic carbon exports explained 81% and 50%, respectively, of the variance in Hg exports, and both were significantly (p < 0.001) correlated with water discharge. Recent measurements indicate that permafrost contains a substantial reservoir of Hg. Consequently, climate warming will likely accelerate the mobilization of Hg from thawing permafrost increasing the export of organic carbon associated Hg and thus potentially exacerbating the production of bioavailable methylmercury from permafrost-dominated northern river basins.

  8. Mercury export from the Yukon River Basin and potential response to a changing climate

    USGS Publications Warehouse

    Schuster, P.F.; Striegl, R.G.; Aiken, G.R.; Krabbenhoft, D.P.; DeWild, J.F.; Butler, K.; Kamark, B.; Dornblaser, M.

    2011-01-01

    We measured mercury (Hg) concentrations and calculated export and yield from the Yukon River Basin (YRB) to quantify Hg flux from a large, permafrost-dominated, high-latitude watershed. Exports of Hg averaged 4400 kg Hg yr-1. The average annual yield for the YRB during the study period was 5.17 ??g m-2 yr-1, which is 3-32 times more than Hg yields reported for 8 other major northern hemisphere river basins. The vast majority (90%) of Hg export is associated with particulates. Half of the annual export of Hg occurred during the spring with about 80% of 34 samples exceeding the U.S. EPA Hg standard for adverse chronic effects to biota. Dissolved and particulate organic carbon exports explained 81% and 50%, respectively, of the variance in Hg exports, and both were significantly (p < 0.001) correlated with water discharge. Recent measurements indicate that permafrost contains a substantial reservoir of Hg. Consequently, climate warming will likely accelerate the mobilization of Hg from thawing permafrost increasing the export of organic carbon associated Hg and thus potentially exacerbating the production of bioavailable methylmercury from permafrost-dominated northern river basins. ?? This article not subject to U.S. Copyright. Published 2011 by the American Chemical Society.

  9. Mercury export from the Yukon River Basin and potential response to a changing climate.

    PubMed

    Schuster, Paul F; Striegl, Robert G; Aiken, George R; Krabbenhoft, David P; Dewild, John F; Butler, Kenna; Kamark, Ben; Dornblaser, Mark

    2011-11-01

    We measured mercury (Hg) concentrations and calculated export and yield from the Yukon River Basin (YRB) to quantify Hg flux from a large, permafrost-dominated, high-latitude watershed. Exports of Hg averaged 4400 kg Hg yr(-1). The average annual yield for the YRB during the study period was 5.17 μg m(-2) yr(-1), which is 3-32 times more than Hg yields reported for 8 other major northern hemisphere river basins. The vast majority (90%) of Hg export is associated with particulates. Half of the annual export of Hg occurred during the spring with about 80% of 34 samples exceeding the U.S. EPA Hg standard for adverse chronic effects to biota. Dissolved and particulate organic carbon exports explained 81% and 50%, respectively, of the variance in Hg exports, and both were significantly (p < 0.001) correlated with water discharge. Recent measurements indicate that permafrost contains a substantial reservoir of Hg. Consequently, climate warming will likely accelerate the mobilization of Hg from thawing permafrost increasing the export of organic carbon associated Hg and thus potentially exacerbating the production of bioavailable methylmercury from permafrost-dominated northern river basins. PMID:21910490

  10. Carbon export and cycling by the Yukon, Tanana, and Porcupine rivers, Alaska, 2001-2005

    USGS Publications Warehouse

    Striegl, R.G.; Dornblaser, M.M.; Aiken, G.R.; Wickland, K.P.; Raymond, P.A.

    2007-01-01

    Loads and yields of dissolved and particulate organic and inorganic carbon (DOC, POC, DIC, PIC) were measured and modeled at three locations on the Yukon River (YR) and on the Tanana and Porcupine rivers (TR, PR) in Alaska during 2001-2005. Total YR carbon export averaged 7.8 Tg C yr-1, 30% as OC and 70% as IC. Total C yields (0.39-1.03 mol C m-2 yr-1) were proportional to water yields (139-356 mm yr-1; r2 = 0.84) at all locations. Summer DOC had an aged component (fraction modern (FM) = 0.94-0.97), except in the permafrost wetland-dominated PR, where DOC was modern. POC had FM = 0.63-0.70. DOC had high concentration, high aromaticity, and high hydrophobic content in spring and low concentration, low aromaticity, and high hydrophilic content in winter. About half of annual DOC export occurred during spring. DIC concentration and isotopic composition were strongly affected by dissolution of suspended carbonates in glacial meltwater during summer.

  11. Chemical complexity and source of the White River Ash, Alaska and Yukon

    USGS Publications Warehouse

    Preece, S.J.; McGimsey, Robert G.; Westgate, J.A.; Pearce, N.J.G.; Hartmann, W.K.; Perkins, W.T.

    2014-01-01

    The White River Ash, a prominent stratigraphic marker bed in Alaska (USA) and Yukon (Canada), consists of multiple compositional units belonging to two geochemical groups. The compositional units are characterized using multiple criteria, with combined glass and ilmenite compositions being the best discriminators. Two compositional units compose the northern group (WRA-Na and WRA-Nb), and two units are present in the eastern group (WRA-Ea and the younger, WRA-Eb). In the proximal area, the ca. 1900 yr B.P. (Lerbekmo et al., 1975) WRA-Na displays reverse zoning in the glass phase and systematic changes in ilmenite composition and estimated oxygen fugacity from the base to the top of the unit. The eruption probably tapped different magma batches or bodies within the magma reservoir with limited mixing or mingling between them. The 1147 cal yr B.P. (calibrated years, approximately equivalent to calendric years) (Clague et al., 1995) WRA-Ea eruption is only weakly zoned, but pumices with different glass compositions are present, along with gray and white intermingled glass in individual pumice clasts, indicating the presence of multiple magmatic bodies or layers. All White River Ash products are high-silica adakites and are sourced from the Mount Churchill magmatic system.

  12. Dissolved Organic Carbon in the Yukon, Tanana and Porcupine Rivers, Alaska

    NASA Astrophysics Data System (ADS)

    Aiken, G. R.; Striegl, R. G.; Wickland, K. P.; Dornblaser, M. M.; Raymond, P. A.

    2006-12-01

    The spatial and temporal variability of dissolved organic carbon (DOC) in the Yukon River (YR) and two major tributaries, the Porcupine River (PR), a black water river draining a watershed almost entirely underlain by permafrost, and the Tanana River (TR), a glacial dominated river, are being studied to better define processes controlling DOC in these systems. Five-year seasonal averages indicate DOC concentrations follow the discharge hydrograph, with highest daily and seasonal flux occurring during spring in YR and PR and during summer-autumn in TR. Largest DOC concentrations and specific UV absorption (SUVA) values, a measure of aromatic carbon content of the DOC and an indicator of DOC source, occurred at all locations during spring snowmelt. Lowest DOC concentration and SUVA occurred during low-flow in winter due to greatly reduced contributions of soil organic matter and to relatively greater influences of ground water. While all sites had comparable DOC concentration during winter, DOC concentration was greatest at PR during spring and summer-autumn, whereas TR had the lowest average DOC and SUVA values. Within the YR, average DOC concentration and SUVA values in spring and summer-autumn increase downriver due to contributions from organic carbon rich tributaries, such as PR, that increase in number and significance as the river flows through Alaska. Most the DOC in each system was comprised of hydrophobic organic acids (HPOA) derived from terrestrial vegetation. During winter, the hydrophilic fraction, determined to be the most biodegradable, was a larger percentage of the DOC than during spring-autumn. During spring, HPOA concentration and SUVA increased significantly at all sites, suggesting that most DOC in spring is derived from terrestrial organic matter that was frozen on the land surface over winter. During spring-autumn, PR had the largest concentration of HPOA and TR had the least. Like DOC concentration, HPOA concentration and SUVA increased down

  13. Seasonal Variability in Dissolved Organic Matter Quantity and Composition from the Yukon River Basin

    NASA Astrophysics Data System (ADS)

    Spencer, R. G.; Aiken, G. R.; Wickland, K. P.; Striegl, R. G.; Hernes, P. J.

    2007-12-01

    The Yukon River basin (YRB) is one of the largest in North America draining an area of 855 x 103 km2 in northwestern Canada and central Alaska and is a major source of terrigenous organic matter to the eastern Bering Sea and Arctic Ocean. The Yukon is also a relatively pristine catchment draining a vast area of taiga that is exceptionally susceptible to climatic change. Dissolved organic matter (DOM) plays a fundamental role in ecosystem biogeochemistry and is ubiquitous in aquatic systems. Samples were collected over a five year period from 2001 to 2005 from a number of locations and at different points in the hydrologic regime throughout the YRB. Sample locations represented different locations on the mainstream of the Yukon River, as well as tributaries ranging from organic rich black waters draining permafrost impacted watersheds to those dominated by glacial melt waters and groundwater. Dissolved organic carbon (DOC) concentrations were observed to vary greatly from 1.5 to 26.1 mgCL-1 depending on source waters and time of year. Specific UV absorbance at 254 nm (SUVA) was also determined and ranged from to 1.3 to 4 highlighting the range in dissolved aromatic carbon content from different sources within the YRB. The hydrophobic acid (HPOA) fraction of the DOM was isolated from samples by XAD-8 resin adsorption for further investigation of DOM composition. The HPOA fraction represented 32 to 57 % of the total DOC for the range of samples studied. SUVA values from the HPOA fraction were higher than the unfractionated water samples (2.5 to 4.4) indicating a higher aromatic content for the HPOA fractions relative to the unfractionated DOM. However, the HPOA SUVA showed a good correlation to the unfractionated water samples SUVA (r2 = 0.84, p<0.01). Dissolved lignin phenols were measured on the HPOA fraction in order to trace vascular plant derived material. The ratios of different lignin phenols (e.g. syringyl to vanillyl; S:V and cinnamyl to vanillyl; C:V) can be

  14. Late Pliocene to late Pleistocene environments preserved at the Palisades Site, central Yukon River, Alaska

    NASA Astrophysics Data System (ADS)

    Matheus, Paul; Begét, James; Mason, Owen; Gelvin-Reymiller, Carol

    2003-07-01

    The Palisades Site is an extensive silt-loam bluff complex on the central Yukon River preserving a nearly continuous record of the last 2 myr. Volcanic ash deposits present include the Old Crow (OCt; 140,000 yr), Sheep Creek (SCt; 190,000 yr), PA (2.02 myr), EC (ca. 2 myr), and Mining Camp (ca. 2 myr) tephras. Two new tephras, PAL and PAU, are geochemically similar to the PA and EC tephras and appear to be comagmatic. The PA tephra occurs in ice-wedge casts and solifluction deposits, marking the oldest occurrence of permafrost in central Alaska. Three buried forest horizons are present in association with dated tephras. The uppermost forest bed occurs immediately above the OCt; the middle forest horizon occurs below the SCt. The lowest forest bed occurs between the EC and the PA tephras, and correlates with the Dawson Cut Forest Bed. Plant taxa in all three peats are common elements of moist taiga forest found in lowlands of central Alaska today. Large mammal fossils are all from common late Pleistocene taxa. Those recovered in situ came from a single horizon radiocarbon dated to ca. 27,000 14C yr B.P. The incongruous small mammal assemblage in that horizon reflects a diverse landscape with both wet and mesic environments.

  15. Impacts of precipitation seasonality and ecosystem types on evapotranspiration in the Yukon River Basin, Alaska

    USGS Publications Warehouse

    Yuan, W.; Liu, S.; Liu, H.; Randerson, J.T.; Yu, G.; Tieszen, L.L.

    2010-01-01

    Evapotranspiration (ET) is the largest component of water loss from terrestrial ecosystems; however, large uncertainties exist when estimating the temporal and spatial variations of ET because of concurrent shifts in the magnitude and seasonal distribution of precipitation as well as differences in the response of ecosystem ET to environmental variabilities. In this study, we examined the impacts of precipitation seasonality and ecosystem types on ET quantified by eddy covariance towers from 2002 to 2004 in three ecosystems (grassland, deciduous broadleaf forest, and evergreen needleleaf forest) in the Yukon River Basin, Alaska. The annual precipitation changed greatly in both magnitude and seasonal distribution through the three investigated years. Observations and model results showed that ET was more sensitive to precipitation scarcity in the early growing season than in the late growing season, which was the direct result of different responses of ET components to precipitation in different seasons. The results demonstrated the importance of seasonal variations of precipitation in regulating annual ET and overshadowing the function of annual precipitation. Comparison of ET among ecosystems over the growing season indicated that ET was largest in deciduous broadleaf, intermediate in evergreen needleleaf, and lowest in the grassland ecosystem. These ecosystem differences in ET were related to differences in successional stages and physiologica responses. Copyright 2010 by the American Geophysical Union.

  16. Indigenous observations of climate change in the Lower Yukon River Basin, Alaska

    USGS Publications Warehouse

    Herman-Mercer, Nicole M.; Schuster, Paul F.; Maracle, Karonhiakt'tie

    2011-01-01

    Natural science climate change studies have led to an overwhelming amount of evidence that the Arctic and Subarctic are among the world's first locations to begin experiencing climate change. Indigenous knowledge of northern regions is a valuable resource to assess the effects of climate change on the people and the landscape. Most studies, however, have focused on coastal Arctic and Subarctic communities with relatively little focus on inland communities. This paper relates the findings from fieldwork conducted in the Lower Yukon River Basin of Alaska in the spring of 2009. Semi-structured interviews were conducted with hunters and elders in the villages of St. Mary's and Pitka's Point, Alaska to document observations of climate change. This study assumes that scientific findings and indigenous knowledge are complementary and seeks to overcome the false dichotomy that these two ways of knowing are in opposition. The observed changes in the climate communicated by the hunters and elders of St. Mary's and Pitka's Point, Alaska are impacting the community in ways ranging from subsistence (shifting flora and fauna patterns), concerns about safety (unpredictable weather patterns and dangerous ice conditions), and a changing resource base (increased reliance on fossil fuels). Here we attempt to address the challenges of integrating these two ways of knowing while relating indigenous observations as described by elders and hunters of the study area to those described by scientific literature.

  17. Effects of disturbance and climate change on ecosystem performance in the Yukon River Basin boreal forest

    USGS Publications Warehouse

    Wylie, Bruce K.; Rigge, Matthew B.; Brisco, Brian; Mrnaghan, Kevin; Rover, Jennifer R.; Long, Jordan

    2014-01-01

    A warming climate influences boreal forest productivity, dynamics, and disturbance regimes. We used ecosystem models and 250 m satellite Normalized Difference Vegetation Index (NDVI) data averaged over the growing season (GSN) to model current, and estimate future, ecosystem performance. We modeled Expected Ecosystem Performance (EEP), or anticipated productivity, in undisturbed stands over the 2000–2008 period from a variety of abiotic data sources, using a rule-based piecewise regression tree. The EEP model was applied to a future climate ensemble A1B projection to quantify expected changes to mature boreal forest performance. Ecosystem Performance Anomalies (EPA), were identified as the residuals of the EEP and GSN relationship and represent performance departures from expected performance conditions. These performance data were used to monitor successional events following fire. Results suggested that maximum EPA occurs 30–40 years following fire, and deciduous stands generally have higher EPA than coniferous stands. Mean undisturbed EEP is projected to increase 5.6% by 2040 and 8.7% by 2070, suggesting an increased deciduous component in boreal forests. Our results contribute to the understanding of boreal forest successional dynamics and its response to climate change. This information enables informed decisions to prepare for, and adapt to, climate change in the Yukon River Basin forest.

  18. Spatially explicit estimation of aboveground boreal forest biomass in the Yukon River Basin, Alaska

    USGS Publications Warehouse

    Ji, Lei; Wylie, Bruce K.; Brown, Dana R. N.; Peterson, Birgit; Alexander, Heather D.; Mack, Michelle C.; Rover, Jennifer R.; Waldrop, Mark P.; McFarland, Jack W.; Chen, Xuexia; Pastick, Neal J.

    2015-01-01

    Quantification of aboveground biomass (AGB) in Alaska’s boreal forest is essential to the accurate evaluation of terrestrial carbon stocks and dynamics in northern high-latitude ecosystems. Our goal was to map AGB at 30 m resolution for the boreal forest in the Yukon River Basin of Alaska using Landsat data and ground measurements. We acquired Landsat images to generate a 3-year (2008–2010) composite of top-of-atmosphere reflectance for six bands as well as the brightness temperature (BT). We constructed a multiple regression model using field-observed AGB and Landsat-derived reflectance, BT, and vegetation indices. A basin-wide boreal forest AGB map at 30 m resolution was generated by applying the regression model to the Landsat composite. The fivefold cross-validation with field measurements had a mean absolute error (MAE) of 25.7 Mg ha−1 (relative MAE 47.5%) and a mean bias error (MBE) of 4.3 Mg ha−1(relative MBE 7.9%). The boreal forest AGB product was compared with lidar-based vegetation height data; the comparison indicated that there was a significant correlation between the two data sets.

  19. Behavior and reproductive success of rock sandpipers breeding on the Yukon-Kuskokwim river delta, Alaska

    USGS Publications Warehouse

    Johnson, M.; Conklin, J.R.; Johnson, B.L.; McCaffery, B.J.; Haig, S.M.; Walters, J.R.

    2009-01-01

    We studied Rock Sandpiper (Calidris ptilocnemis) breeding behavior and monitored reproductive success from 1998 to 2005 on the Yukon-Kuskokwim River Delta, Alaska, USA. We banded 24 adults and monitored 45 nests. Annual return rate of adults ranged between 67 and 100%. Six pairs of Rock Sandpipers bred at our study site for ???2 years, and among these we did not observe mate change (i.e., when both members of a pair returned and each mated with a new individual). Nests were typically initiated by mid-May and 53% of females laid second clutches if first clutches were lost through mid-June. Males regularly incubated clutches during the morning (0800-1259 hrs AKDT) and afternoon (1300-1759 hrs) and rarely during the evening (1800-2300 hrs), whereas female incubation was relatively consistent throughout the day. Apparent nest success (percent of known nests successfully hatching > 1 chick) among first and second nests was 19 and 44%, respectively (n = 45). A minimum of 44% of hatching nests fledged at least one young. Males cared for young but half of females deserted mate and brood 1-7 days post-hatch. This first description of North American Rock Sandpiper breeding behavior from a color-marked population complements previous work on this species on the Chukotsky Peninsula, Russia.

  20. Observations and Impacts of Permafrost Thaw in the Lower Yukon River Basin and Yukon Delta Region: the Importance of Local Knowledge

    NASA Astrophysics Data System (ADS)

    Herman-Mercer, N. M.; Elder, K.; Toohey, R.; Mutter, E. A.

    2015-12-01

    In regions of the arctic and subarctic baseline measurements of permafrost dynamics are lacking and scientific research can be especially expensive when remote sensing techniques are utilized. This research demonstrated the importance of local observations, a powerful tool for understanding landscape change, such as permafrost dynamics. Fifty-five interviews were recently conducted with community members in four villages of the lower Yukon River Basin and Yukon Delta to understand local environmental and landscape changes and the impacts these changes may be having on the lives and livelihoods of these communities. The interviews were semi-structured and focused on many climate and landscape change factors including knowledge of permafrost in their community or the surrounding landscape. All positive respondents stated that they believe the permafrost is thawing. The research revealed that residents of the arctic and subarctic interact with permafrost in a variety of ways. Some people utilize permafrost to store food resources and have found that they have to dig deeper presently than in their youth in order to find ground cold enough. Others are involved in digging graves and report encountering easier excavation in recent years. Subsistence hunters and gatherers travel long distances by snowmobile and boat, and have noticed slumping ground, eroding river banks and coast lines, as well as land that seems to be rising. Finally, all residents of the arctic and subarctic interact with permafrost in terms of the stability of their homes and other infrastructure. Many interview participants complained of their houses leaning and needing more frequent adjustment than in the past. Indigenous residents of the arctic and subarctic have intimate relationships with their landscape owing to their subsistence lifestyle and are also connected to the landscape of the past through the teachings of their elders. Further, arctic and subarctic communities will sustain the majority

  1. Seasonal variability in the composition of dissolved organic matter in the Yukon River, Alaska

    NASA Astrophysics Data System (ADS)

    Aiken, G.; Cao, X.; Mao, J.; Stubbins, A.; Schmidt-Rohr, K.; Spencer, R. G.

    2015-12-01

    Modern analytical approaches allow for detailed characterization of the composition of dissolved organic matter (DOM) in aquatic systems. The utility of advanced FTICR-MS and 13C-NMR approaches is presented for assessing the seasonal variability in DOM composition for samples collected across the hydrograph (2008 and 2009) from the Yukon River at Pilot Station, Alaska. FTICR-MS analyses were obtained on whole water samples while one- and two-dimensional solid-state NMR analyses were performed on the hydrophobic organic acid (HPOA) and transphilic organic acid (TPIA) fractions obtained using XAD resins (accounting for 64-74% of the DOM). Both approaches indicated that lignin-derived and carboxyl-rich alicyclic molecules (CRAM) were major fractions of all samples collected throughout the year, and that contributions from black carbon were minor. Each approach also provided unique information. FTICR-MS indicated the presence in spring of compounds containing sulfur that previously were identified to be atmospherically deposited combustion products in glacial meltwaters. These likely were deposited with snowfall. NMR analyses indicated that HPOA isolates from the spring period were characterized by greater contributions from lignin residues and carbohydrate-like materials than those from summer-autumn and winter. In addition, the spring TPIA samples had a predominance of carbohydrate, which was much less evident in the structures of summer-autumn and winter TPIA isolates. Spring DOM, therefore, was representative of inputs from freshly leached plant materials. These relatively fresh organic materials were depleted in summer-fall and winter samples, indicating that summer-fall and especially winter DOM was associated with more extensively degraded DOM and older DOM pools. These results provide chemical evidence supporting observations that spring freshet DOM in Arctic rivers is more biolabile than DOM exported at other times of the year.

  2. Variation in the population structure of Yukon River chum and coho salmon: Evaluating the potential impact of localized habitat degradation

    USGS Publications Warehouse

    Olsen, J.B.; Spearman, W.J.; Sage, G.K.; Miller, S.J.; Flannery, B.G.; Wenburg, J.K.

    2004-01-01

    We used microsatellite and mitochondrial DNA-restriction fragment length polymorphism (mtDNA-RFLP) analyses to test the hypothesis that chum salmon Oncorhynchus keta and coho salmon O. kisutch in the Yukon River, Alaska, exhibit population structure at differing spatial scales. If the hypothesis is true, then the risk of losing genetic diversity because of habitat degradation from a gold mine near a Yukon River tributary could differ between the two species. For each species, collections were made from two tributaries in both the Innoko and Tanana rivers, which are tributaries to the lower and middle Yukon River. The results revealed a large difference in the degree and spatial distribution of population structure between the two species. For chum salmon, the microsatellite loci (F-statistic [FST] = 0.021) and mtDNA (F ST = -0.008) revealed a low degree of interpopulation genetic diversity on a relatively large geographic scale. This large-scale population structure should minimize, although not eliminate, the risk of genetic diversity loss due to localized habitat degradation. For coho salmon, the microsatellites (FST = 0.091) and mtDNA (FST = 0.586) revealed a high degree of interpopulation genetic diversity on a relatively small geographic scale. This small-scale population structure suggests that coho salmon are at a relatively high risk of losing genetic diversity due to lo-calized habitat degradation. Our study underscores the importance of a multispecies approach for evaluating the potential impact of land-use activities on the genetic diversity of Pacific salmon.

  3. Ecology of invasive Melilotus alba on Alaskan glacial river floodplains

    Technology Transfer Automated Retrieval System (TEKTRAN)

    White sweetclover has recently invaded glacial river floodplains in Alaska. We sampled vegetation and measured environmental variables along transects located along the Nenana, Matanuska, and Stikine Rivers to describe plant communities and to determine the effects of white sweetclover on other plan...

  4. Microbial Diversity in Soil Cores From the Yukon River Basin, Alaska

    NASA Astrophysics Data System (ADS)

    Baedecker, M.; Kirshtein, J. D.; Wickland, K. P.; Metge, D. W.; Schuster, P. F.; Voytek, M. A.

    2006-12-01

    Understanding the microbial environment in permafrost areas is important for understanding processes that release carbon and other nutrients from soils as a result of permafrost melting. Soils were collected in August 2005 from two sites in the Yukon River Basin, Alaska, and examined for microbial diversity as part of a larger project to investigate carbon cycling within the river basin. One site was located at the Bonanza Creek Long- Term Ecological Research Site near Fairbanks in an area of discontinuous permafrost and the other site was collected 400 kilometers to the north near Coldfoot in an area of continuous permafrost within the Arctic Circle. Both sites are characterized as black spruce forest and permafrost is 42-55 cm below land surface. Soil pore waters in the active layer at the Bonanza Creek site had a higher pH (5.06 versus 4.35), lower SO4 and DOC, and higher dissolved CH4 compared to the Coldfoot site. Dissolved oxygen was measured at >1.0 mg/L in water pumped from piezometers at both sites. Soil samples were collected from a range of depths above and below the permafrost and analyzed for total bacteria, for most probable number (MPN) of nine metabolic types of microorganisms, and for five metabolic types of microorganisms by quantitative polyermase chain reaction (QPCR). Soil geochemistry and climatic conditions affected the microbial abundances and distributions found at these two sites. The total number of bacteria by direct count ranged from 105 to 107 cells per gram dry weight (gdw) sediment with living cells comprising 1.4 to 98% of the total enumerated bacteria. In near-surface samples (top 40 cm), the MPN results indicate that aerobes, fermenters, humic acid reducers, and iron reducers account for most of the total bacteria. Nitrifiers and denitrifiers were found in a few samples, whereas sulfate reducers and methanogens were below our detection limit using the MPN method. The QPCR results indicated the presence of methanogens in 9 of 14

  5. Correlation of Fish and Benthic Macroinvertebrate Communities With Multi-scale Environmental Descriptors in Wadeable Streams of the Yukon River Basin

    NASA Astrophysics Data System (ADS)

    Bailey, J. L.; Bailey, R. C.; Scott, R. J.

    2005-05-01

    We sampled fish and benthic macroinvertebrates at thirty wadeable stream sites in the Yukon River basin in Yukon Territory, Canada during July, 2004, to establish reference conditions in Yukon River basin stream communities. We also measured water quality (eg. temperature, dissolved oxygen, conductivity, pH), stream flow, substrate characteristics and riparian vegetation at each site. Water samples from each site were subsequently analyzed for nutrients and metals. In addition, catchment area, catchment perimeter, catchment land cover, distance of each site to major water bodies and stream barriers were determined through Geographic Information System and satellite photography analysis. Fish and benthic macroinvertebrate community structures and their relationships with the multi-scale description of the stream environment were quantified with non-metric multidimensional scaling, principal component analysis, and correlation analysis.

  6. Nutrient (N, P) loads and yields at multiple scales and subbasin types in the Yukon River basin, Alaska

    USGS Publications Warehouse

    Dornblaser, M.M.; Striegl, R.G.

    2007-01-01

    Loads and yields of dissolved and particulate nitrogen (N) and phosphorus (P) were measured and modeled at three locations on the Yukon River (YR) and on the Tanana and Porcupine Rivers in Alaska during 2001-2005. Total export of N and P upstream of Yukon Delta averaged 120 Gg N a-1 and 56 Gg P a-1, respectively, with 43.5% of total N (TN) as dissolved organic N, and 98% of total P (TP) as particulate phosphorus. Approximately half of the annual export of TN and TP occurred during spring. Hydrologic yields ofTN (5.6-13.3 mmol N m-2 a-1) and TP (0.8-9.0 mmol P m-2 a-1) were least in the Porcupine basin and greatest in the Tanana basin and were proportional to water yield. Comparison of current and historical dissolved organic matter (DOM) export from the basin indicates decreased DON export with respect to total water discharge during summer and autumn in recent decades. Any possible climate-related change in annual water discharge will result in proportional changes in N and P export.

  7. Source water controls on the character and origin of dissolved organic matter in streams of the Yukon River basin, Alaska

    NASA Astrophysics Data System (ADS)

    O'Donnell, Jonathan A.; Aiken, George R.; Kane, Evan S.; Jones, Jeremy B.

    2010-09-01

    Climate warming and permafrost degradation at high latitudes will likely impact watershed hydrology, and consequently, alter the concentration and character of dissolved organic carbon (DOC) in northern rivers. We examined seasonal variation of DOC chemistry in 16 streams of the Yukon River basin, Alaska. Our primary objective was to evaluate the relationship between source water (shallow versus deep groundwater flow paths) and DOC chemical composition. Using base cation chemistry and principal component analysis, we observed high contributions of deep groundwater to glacial and clearwater streams, whereas blackwater streams received larger contributions from shallow groundwater sources. DOC concentration and specific ultraviolet absorbance peaked during spring snowmelt in all streams, and were consistently higher in blackwater streams than in glacial and clearwater streams. The hydrophobic acid fraction of DOC dominated across all streams and seasons, comprising between 35% and 56% of total DOC. The hydrophilic acid fraction of DOC was more prominent in glacial (23% ± 3%) and clearwater streams (19% ± 1%) than in blackwater streams (16% ± 1%), and was enriched during winter base flow (29% ± 1%) relative to snowmelt and summer base flow. We observed that an increase in the contribution of deep groundwater to streamflow resulted in decreased DOC concentration, aromaticity, and DOC-to-dissolved organic nitrogen ratio, and an increase in the proportion of hydrophilic acids relative to hydrophobic acids. Our findings suggest that future permafrost degradation and higher contributions of groundwater to streamflow may result in a higher fraction of labile DOM in streams of the Yukon basin.

  8. Pliocene terrace gravels of the ancestral Yukon River near Circle, Alaska: Palynology, paleobotany, paleoenvironmental reconstruction and regional correlation

    USGS Publications Warehouse

    Ager, T.A.; Matthews, J.V., Jr.; Yeend, W.

    1994-01-01

    Gravels deposited by the ancestral Yukon River are preserved in terrace remnants on the margins of the Yukon River valley near the village of Circle in east-central Alaska. Plant fossils recovered from sandy silt lenses within these gravels include cones and needles of Picea and Larix and a variety of seeds. Seed types include several taxa which no longer grow in Alaska, such as Epipremnum, Prunus and Weigela. Pollen types recovered from these deposits represent tree and shrub taxa that grow in interior Alaska today, such as Picea, Larix, Betula and Alnus, as well as several taxa that no longer grow in interior Alaska today, such as Pinus, Tsuga, Abies and Corylus. Pollen of herb taxa identified include Gramineae, Cyperaceae, Caryophyllaceae, Compositae, Polemonium and Epilobium. The fossil flora from the gravels near Circle are similar and probably age-equivalent to the flora recovered from the Nenana Gravel in the Alaska Range 250 km to the south. Palynological and tectonic evidence summarized in this paper now suggests that the Nenana Gravel was deposited during the early and middle Pliocene. The presence of plant fossils of Tsuga, Abies, Pinus, Weigela and Prunus suggests that the mean annual temperature (MAT) of eastern interior Alaska during the early and middle Pliocene was perhaps 7-9??C warmer and less continental than today's MAT of -6.4??C. ?? 1994.

  9. Warming in the Yukon River Basin is Likely to Release Substantial Amounts of Soil Organic Carbon

    NASA Astrophysics Data System (ADS)

    Juday, G. P.; Huntington, T. G.

    2005-12-01

    In recent decades the Yukon River Basin (YRB) in northwestern Canada and central Alaska has experienced a substantial warming trend resulting in a variety of geophysical and biological responses. Climatologic measurements consistent with rapid warming in the YRB during the last several decades of the 20th century include surface air temperature (especially daily minima), number of frost-free days, and the number of very warm days. During the 20th century daily maxima in the warm season in the YRB have increased only weakly, and modest autumn cooling occurred. Indirect indicators of warming include shrinkage in lake area, decreases in glacier mass, increased fire frequency and annual area burned, and changes in permafrost thickness and permafrost temperature. Changes in tree growth rates and susceptibility to pests have been related to warming and drying in interior Alaska. Oral histories of Alaska Natives have also revealed many other warming related changes in the YRB. If ongoing warming trends continue there is a concern that large stores of soil organic carbon (SOC) will be at risk for release to the atmosphere through heterotrophic decomposition. Warming tends to accelerate microbial decomposition at a faster rate than net primary productivity. One of the most important effects of warming in the YRB is likely to be its influence on the hydrologic and cryospheric regimes. Warming may be accompanied by soil drying and lowering of the water table in wetlands and lakes exposing more SOC to aerobic decomposition. A substantial portion of the YRB is underlain by permafrost that thaws to a variable depth (active layer) each summer. Increasing the thickness of the active layer exposes more SOC to microbial decomposition. Increasing the burned area results in direct SOC losses by oxidation during the fire and decreases albedo that warms surface soils and increases the thickness of the active layer. Warming and increasing length of the growing season increases seasonal

  10. Cryogenic structure and ice content of lacustrine sediments in the Yukon River Basin, Alaska

    NASA Astrophysics Data System (ADS)

    Kanevskiy, M. Z.; Jorgenson, M. T.; Shur, Y.; O'Donnell, J.; Harden, J. W.; Fortier, D.

    2009-12-01

    Lacustrine sediments often present a significant part of the upper permafrost of plains and lowlands of Alaska. Lacustrine sediments in their contemporary state vary from ice-poor to extremely ice-rich. The ice content depends on initial conditions of freezing and further history of permafrost development, which can include partial degradation and recovery of permafrost. In Alaska, the primary mechanism of freezing and cryogenic structure formation of lacustrine sediments is para-syngenetic (term by E.M. Katasonov, 1978), typical of sediments accumulated in lakes surrounded by permafrost. Though the freezing of such sediments occurs before or immediately after the termination of sedimentation (similar to syngenetic permafrost), the freezing conditions and cryogenic structure of para-syngenetic permafrost are similar to epigenetic permafrost. The ice lenses in para-syngenetic sediments are often inclined, and the ice content is relatively small in the central parts of refrozen taliks. This type of ice distribution is generally governed by the migration of water to multidirectional fronts of freezing. We studied the cryogenic structure of lacustrine sediments across different regions of the Yukon River Basin, Alaska, including Koyukuk Flats (Hozatka Lake area), Innoko Lowlands, and Tanana-Kuskokwim Lowlands (Lake Minchumina area). Study sites are located in the discontinuous permafrost zone, where permafrost was encountered mainly within uplifted peat plateaus. Field work included study of natural exposures and drilling. The upper part of studied sections is formed by frozen organic soils up to 2-3 -m -thick underlain by lacustrine silt, which is mostly ice-rich. Volume of visible ice in silt reaches at places 40% and more. A combination of layered and reticulate cryostructures is the most typical and common cryostructure assemblage. The thickness of ice lenses generally varies from 1 to 5 cm and occasionally reaches 10 cm. Aggradation of ice during the freezing of

  11. Biomarkers of contaminant exposure in northern pike (Esox lucius) from the Yukon River Basin, Alaska

    USGS Publications Warehouse

    Hinck, J.E.; Blazer, V.S.; Denslow, N.D.; Myers, M.S.; Gross, T.S.; Tillitt, D.E.

    2007-01-01

    As part of a larger investigation, northern pike (n = 158; Esox lucius) were collected from ten sites in the Yukon River Basin (YRB), Alaska, to document biomarkers and their correlations with organochlorine pesticide (total p,p'-DDT, total chlordane, dieldrin, and toxaphene), total polychlorinated biphenyls (PCBs), and elemental contaminant (arsenic, cadmium, copper, lead, total mercury, selenium, and zinc) concentrations. A suite of biomarkers including somatic indices, hepatic 7-ethoxyresorufin O-deethylase (EROD) activity, vitellogenin concentrations, steroid hormone (17B- ustradiol and 16-kebtestosteront) concentrations, splenic macrophage aggregates (MAs), oocyte atresia, and other microscopic anomalies in various tissues were documented in YRB pike. Mean condition factor (0.50 to 0.68), hepatosomatic index (1.00% to 3.56%), and splenosomatic index (0.09% to 0.18%) were not anomalous at any site nor correlated with any contaminant concentration. Mean EROD activity (0.71 to 17.51 pmol/min/mg protein) was similar to basal activity levels previously measured in pike and was positively correlated with selenium concentrations (r = 0.88, P < 0.01). Vitellogenin concentrations in female (0.09 to 5.32 mg/mL) and male (0.01 mg/mL in male pike from multiple sites indicated exposure to estrogenic compounds. Mean steroid hormone concentrations and percent oocyte atresia were not anomalous in pike from any YRB site. Few site differences were significant for mean MA density (1.86 to 6.42 MA/mm2), size (812 to 1481 ??m2), and tissue occupied (MA-%; 0.24% to 0.75%). A linear regression between MA-% and total PCBs was significant, although PCB concentrations were generally low in YRB pike (???63 ng/g), and MA-% values in female pike (0.24% to 0.54%) were lower than in male pike (0.32% to 0.75%) at similar PCB concentrations. Greater numbers of MAs were found as zinc concentrations increased in YRB female pike, but it is unlikely that this is a causative relationship

  12. Evaluation of three gears for sampling spawning populations of rainbow trout in a large Alaskan river

    USGS Publications Warehouse

    Schwanke, C.J.; Hubert, W.A.

    2004-01-01

    Alternatives to electrofishing are needed for sampling sexually mature rainbow trout Oncorhynchus mykiss during the spawning season in large Alaskan rivers. We compared hook and line, beach seining, and actively fished gill nets as sampling tools. Beach seining and active gill netting yielded similar catch rates, length frequencies, and sex ratios of sexually mature fish. Hook-and-line sampling was less effective, with a lower catch rate and selectivity for immature fish and sexually mature females. We conclude that both beach seining and active gill netting can serve as alternatives to electrofishing for sampling sexually mature rainbow trout stocks during the spawning season in large rivers with stable spring flows and spawning areas with few snags.

  13. Increased groundwater to stream discharge from permafrost thawing in the Yukon River basin: Potential impacts on lateral export of carbon and nitrogen

    USGS Publications Warehouse

    Walvoord, M.A.; Striegl, R.G.

    2007-01-01

    Arctic and subarctic watersheds are undergoing climate warming, permafrost thawing, and thermokarst formation resulting in quantitative shifts in surface water - groundwater interaction at the basin scale. Groundwater currently comprises almost one fourth of Yukon River water discharged to the Bering Sea and contributes 5-10% of the dissolved organic carbon (DOC) and nitrogen (DON) and 35-45% of the dissolved inorganic carbon (DIC) and nitrogen (DIN) loads. Long-term strearnflow records (>30 yrs) of the Yukon River basin indicate a general upward trend in groundwater contribution to streamflow of 0.7-0.9%/yr and no pervasive change in annual flow. We propose that the increases in groundwater contributions were caused predominately by climate warming and permafrost thawing that enhances infiltration and supports deeper flowpaths. The increased groundwater fraction may result in decreased DOC and DON and increased DIC and DIN export when annual flow remains unchanged.

  14. Nitrogen cycling processes and microbial community composition in bed sediments in the Yukon River at Pilot Station

    NASA Astrophysics Data System (ADS)

    Repert, Deborah A.; Underwood, Jennifer C.; Smith, Richard L.; Song, Bongkeun

    2014-12-01

    Information on the contribution of nitrogen (N)-cycling processes in bed sediments to river nutrient fluxes in large northern latitude river systems is limited. This study examined the relationship between N-cycling processes in bed sediments and N speciation and loading in the Yukon River near its mouth at the Bering Sea. We conducted laboratory bioassays to measure N-cycling processes in sediment samples collected over distinct water cycle seasons. In conjunction, the microbial community composition in the bed sediments using genes involved in N-cycling (narG, napA, nosZ, and amoA) and 16S rRNA gene pyrosequences was examined. Temporal variation was observed in net N mineralization, nitrate uptake, and denitrification rate potentials and correlated strongly with sediment carbon (C) and extractable N content and microbial community composition rather than with river water nutrient concentrations. The C content of the bed sediment was notably impacted by the spring flood, ranging from 1.1% in the midst of an ice-jam to 0.1% immediately after ice-out, suggesting a buildup of organic material (OM) prior to scouring of the bed sediments during ice break up. The dominant members of the microbial community that explained differences in N-processing rates belonged to the genera Crenothrix, Flavobacterium, and the family of Comamonadaceae. Our results suggest that biogeochemical processing rates in the bed sediments appear to be more coupled to hydrology, nutrient availability in the sediments, and microbial community composition rather than river nutrient concentrations at Pilot Station.

  15. Nitrogen cycling processes and microbial community composition in bed sediments in the Yukon River at Pilot Station

    USGS Publications Warehouse

    Repert, Deborah A.; Underwood, Jennifer C.; Smith, Richard L.; Song, Bongkeun

    2014-01-01

    Information on the contribution of nitrogen (N)-cycling processes in bed sediments to river nutrient fluxes in large northern latitude river systems is limited. This study examined the relationship between N-cycling processes in bed sediments and N speciation and loading in the Yukon River near its mouth at the Bering Sea. We conducted laboratory bioassays to measure N-cycling processes in sediment samples collected over distinct water cycle seasons. In conjunction, the microbial community composition in the bed sediments using genes involved in N-cycling (narG, napA, nosZ, and amoA) and 16S rRNA gene pyrosequences was examined. Temporal variation was observed in net N mineralization, nitrate uptake, and denitrification rate potentials and correlated strongly with sediment carbon (C) and extractable N content and microbial community composition rather than with river water nutrient concentrations. The C content of the bed sediment was notably impacted by the spring flood, ranging from 1.1% in the midst of an ice-jam to 0.1% immediately after ice-out, suggesting a buildup of organic material (OM) prior to scouring of the bed sediments during ice break up. The dominant members of the microbial community that explained differences in N-processing rates belonged to the genera Crenothrix,Flavobacterium, and the family of Comamonadaceae. Our results suggest that biogeochemical processing rates in the bed sediments appear to be more coupled to hydrology, nutrient availability in the sediments, and microbial community composition rather than river nutrient concentrations at Pilot Station.

  16. Hydrological changes prints in subarctic watersheds discharge records: a case study in the Duke River watershed, Yukon, Canada.

    NASA Astrophysics Data System (ADS)

    Chesnokova, A.; Baraer, M.

    2015-12-01

    Hydrological changes from alpine glacierized watersheds have been reported from almost all the regions of the world. In most cases those changes have, or are foreseen to have, marked impacts on water resources with implications for downstream population and ecosystems. One of the ways to assess climate change impacts on glacierized watersheds is to conduct appropriate statistical analyses on historical hydrometric data where long and accurate time series exist. In the Yukon, Canada, a fair number of hydrometric time series are made accessible by institutions such as Environment Canada or the Yukon National Parks Organisation. Some of those time series have been studied previously at a regional scale in the territory. In the present study, focusing on the Duke River watershed area, we reanalyse these datasets based on a larger number of discharge characteristics and compare results with regional meteorological data analysis. We perform non-parametric trend analysis to assess long-term changes in watersheds response to climate-induced variability. Eight watersheds with varying glacierized area were chosen for this study. Main glaciers in the region are situated in St. Elias Mountains and are characterised by ubiquitous mass loss (Arendt et al., 2002; Barrand and Sharp, 2010). Historical hydrometric data analysis shows two distinct hydrological regimes in the area: (i) - snow fed rivers with peak runoff following spring snowmelt, and (ii) - glacier fed rivers with peak runoff following glacier ablation in July. While total discharge during ablation season does not vary significantly between watersheds with different regimes, the difference in late summer runoff is close to 50%. Moreover, trend analysis provides evidence of changes in hydrological regimes in the area. As a response to ubiquitous temperature increase, hydrologically active period for highly glacieized watershed (with glacierized area of 30%) has shifted from the beginning of August to the beginning of

  17. Success in Outreach and Education Through a Partnership Approach Between Government and Grass Roots: The Yukon River Basin Water Quality Monitoring Program

    NASA Astrophysics Data System (ADS)

    Maracle, B. K.; Schuster, P. F.

    2008-12-01

    The U.S. Geological Survey (USGS) recently concluded a five-year water quality study (2001-2005) of the Yukon River and its major tributaries. One component of the study was to establish a water quality baseline providing a frame of reference to assess changes in the basin that may result from climate change. As the study neared its conclusion, the USGS began to foster a relationship with the Yukon River Inter-Tribal Watershed Council (YRITWC). The YRITWC was in the process of building a steward-based Yukon River water quality program. Both the USGS and the YRITWC recognized the importance of collaboration resulting in mutual benefits. Through the guidance, expertise, and training provided by the USGS, YRITWC developed and implemented a basin-wide water quality program. The YRITWC program began in March, 2006 utilizing USGS protocols, techniques, and in-kind services. To date, more than 300 samplings and field measurements at more than 25 locations throughout the basin (twice the size of California) have been completed by more than 50 trained volunteers. The Yukon River Basin baseline water quality database has been extended from 5 to 8 years due to the efforts of the YRITWC-USGS collaboration. Basic field measurements include field pH, specific conductance, dissolved oxygen, and water temperature. Samples taken for laboratory analyses include major ions, dissolved organic carbon, greenhouse gases, nutrients, and stable isotopes of hydrogen and oxygen, and selected trace elements. Field replicates and blanks were introduced into the program in 2007 for quality assurance. Building toward a long-term dataset is critical to understanding the effects of climate change on river basins. Thus, relaying the importance of long-term water-quality databases is a main focus of the training workshops. Consistencies in data populations between the USGS 5-year database and the YRITWC 3-year database indicate protocols and procedures made a successful transition. This reflects the

  18. Changing Conditions In The Yukon River Basin, Alaska: Biological, Geographical, And Hydrological Research Of The U.S. Geological Survey Alaska Science Center

    NASA Astrophysics Data System (ADS)

    Brabets, T. P.; Frenzel, S. A.; Markon, C.; Degange, A. R.

    2006-12-01

    To address the need for understanding past, present, and future conditions in the northern latitudes, the United States Geological Survey's (USGS) Alaska Science Center conducts extensive research in the Yukon River Basin. The basin originates in Canada and spans Alaska from east to west encompassing diverse landscapes in the Arctic and sub-Arctic. Within this large watershed, USGS research is focused on understanding the rapidly changing conditions in the land cover and fires, fish and wildlife populations, and the hydrologic cycle. Some of Alaska largest and most extensive fires occur in the Yukon River Basin. Research suggests that recent fire frequency outpaces the forest replenishment. To provide a more thorough assessment of current fires, and prediction of future fire threats, Landsat imagery with its 30-m spatial resolution and 30-year history allow for unprecedented analysis of historical and existing landscape cover, the effects of fire and climate change on lake drying, and updating of fire burn boundaries. Additionally, caribou have been shown to avoid burned areas for at least 60 years because forage lichens were eliminated and preferred forage may require over 100 years to reach pre-fire abundance. Glaciers in Alaska and in Canada feed the Tanana River, a major tributary to the Yukon River. Gulkana Glacier is one such glacier where the USGS has measured the mass balance continuously since 1966. There has been a cumulative mass loss of more than 15 meters water equivalent since 1966, with two-thirds of that loss occurring since 1990. Streamflow statistics from long-term gaging stations show a tendency for earlier ice break up in the spring and earlier snowmelt peak flows. Glacier-fed streams show higher summer flows as warmer temperatures increased glacier melt. To provide a better understanding of the factors that regulate salmon production, USGS has examined the characteristics of chum salmon spawning habitats and survival of juvenile salmon at two

  19. The Intersection of Environmental Variability, Policy, and Human Values: International Treaties, Yukon River Salmon, and Food Security in a Changing Arctic (Invited)

    NASA Astrophysics Data System (ADS)

    Gerlach, S.; Loring, P. A.; Murray, M. S.

    2009-12-01

    2009 was a particularly devastating year for rural communities of the Yukon River in Alaska. For a number of reasons, including annual variability in Chinook and Chum salmon runs, imperfect monitoring and information, “best practices” management decisions by regulatory agencies, and international treaty obligations related to conservation and total allowable catch allocation, the smokehouses and freezers of many Alaska Native families, particularly those in up-river communities in the Yukon Flats region, are empty; a problem that has prompted Alaska’s Governor Sean Parnell to ask the US Federal Government to declare a disaster. However, depending on whom you ask, this year’s management of these resources, which provide food security and enable self-reliance in rural communities, may be evaluated as a failure or as a success. How can we reconcile an institutional assessment that claims success as defined in terms of internationally-agreed upon conservation and escapement goals, with the negative economic and health impacts on communities? We use this case to illustrate how the whole Yukon River watershed and drainage, including Alaska and Canada, provides an elegant, geographic context for the discussion and analysis of the human dimensions of environmental change and regional sustainability. Policymakers have arguably gone to great lengths to reconcile competing ‘uses’ of the Yukon River, including commercial and subsistence uses as well as conservation goals, but while managers continue to strive to be ‘adaptive learners’ in their approach to balancing these goals, the impacts on rural communities are immediate and cumulative, synergistic, temporally and spatially scaled, and directly related to rural livelihoods, community health, well-being and sustainability. The cost of this ‘adaptive’ process may be too high, both for the ecosystem and for the people who live there. Are we asking too much of the Yukon River? Are we asking too much of the

  20. Historical growth of Bristol Bay and Yukon River, Alaska chum salmon (Oncorhynchus keta) in relation to climate and inter- and intraspecific competition

    NASA Astrophysics Data System (ADS)

    Agler, Beverly A.; Ruggerone, Gregory T.; Wilson, Lorna I.; Mueter, Franz J.

    2013-10-01

    We examined Bristol Bay and Yukon River adult chum salmon scales to determine whether climate variability, such as changes in sea surface temperature and climate indices, and high pink and Asian chum salmon abundance reduced chum salmon growth. Annual marine growth increments for 1965-2006 were estimated from scale growth measurements and were modeled as a function of potential explanatory variables using a generalized least squares regression approach. First-year growth of salmon originating from Bristol Bay and the Yukon River showed increased growth in association with higher regional ocean temperatures and was negatively affected by wind mixing and ice cover. Third-year growth was lower when Asian chum salmon were more abundant. Contrary to our hypothesis, warmer large-scale sea surface temperatures in the Gulf of Alaska were also associated with reduced third-year growth. Negative effects of high abundances of Russian pink salmon on third-year growth provided some evidence for interspecific interactions, but the effects were smaller than the effects of Asian chum salmon abundance and Gulf of Alaska sea surface temperature. Although the relative effects of Asian chum salmon and sea surface temperature on the growth of Yukon and Bristol Bay chum salmon were difficult to untangle, we found consistent evidence that high abundances of Asian chum salmon contributed to a reduction in the growth of western Alaska chum salmon.

  1. A promising tool for subsurface permafrost mapping-An application of airborne geophysics from the Yukon River Basin, Alaska

    USGS Publications Warehouse

    Abraham, Jared

    2011-01-01

    In the area of Fort Yukon, the AEM survey shows elevated resistivities extending to depth, likely indicative of thick permafrost. This depth corresponds well to observations from a borehole drilled in the area in the lat

  2. Utilizing chromophoric dissolved organic matter measurements to derive export and reactivity of dissolved organic carbon exported to the Arctic Ocean: A case study of the Yukon River, Alaska

    USGS Publications Warehouse

    Spencer, R.G.M.; Aiken, G.R.; Butler, K.D.; Dornblaser, M.M.; Striegl, R.G.; Hernes, P.J.

    2009-01-01

    The quality and quantity of dissolved organic matter (DOM) exported by Arctic rivers is known to vary with hydrology and this exported material plays a fundamental role in the biogeochemical cycling of carbon at high latitudes. We highlight the potential of optical measurements to examine DOM quality across the hydrograph in Arctic rivers. Furthermore, we establish chromophoric DOM (CDOM) relationships to dissolved organic carbon (DOC) and lignin phenols in the Yukon River and model DOC and lignin loads from CDOM measurements, the former in excellent agreement with long-term DOC monitoring data. Intensive sampling across the historically under-sampled spring flush period highlights the importance of this time for total export of DOC and particularly lignin. Calculated riverine DOC loads to the Arctic Ocean show an increase from previous estimates, especially when new higher discharge data are incorporated. Increased DOC loads indicate decreased residence times for terrigenous DOM in the Arctic Ocean with important implications for the reactivity and export of this material to the Atlantic Ocean. Citation: Spencer, R. G. M., G. R. Aiken, K. D. Butler, M. M. Dornblaser, R. G. Striegl, and P. J. Hernes (2009), Utilizing chromophoric dissolved organic matter measurements to derive export and reactivity of dissolved organic carbon exported to the Arctic Ocean: A case study of the Yukon River, Alaska, Geophys. Res. Lett., 36, L06401, doi:10.1029/ 2008GL036831. Copyright 2009 by the American Geophysical Union.

  3. REPETITIVE DIGITAL NOAA-AVHRR DATA FOR ALASKAN ENGINEERING AND SCIENTIFIC APPLICATIONS.

    USGS Publications Warehouse

    Christie, William M.; Pawlowski, Robert J.; Fleming, Michael D.

    1986-01-01

    Selected digitally enhanced NOAA - Advanced Very High Resolution Radiometer (AVHRR) images taken by the NOAA 6, 7, 8 and 9 Polar Orbiting Satellites demonstrate the capability and application of repetitive low-resolution satellite data to Alaska's engineering and science community. Selected cloud-free visible and thermal infrared images are enhanced to depict distinct oceanographic and geologic processes along Alaska's west coast and adjacent seas. Included are the advance of the Bering Sea ice field, transport of Yukon River sediment into Norton Sound, and monitoring of plume trajectories from the Mount Augustine volcanic eruptions. Presented illustrations are representative of the 94 scenes in a cooperative USGS EROS/NOAA Alaskan AVHRR Digital Archive. This paper will discuss the cooperative efforts in establishing the first year data set and identifying Alaskan applications.

  4. Ecosystem types of boreal forest in the North Klondike River Valley, Yukon Territory, Canada, and their productivity potentials.

    PubMed

    Kojima, S

    1996-01-01

    Vegetation, environmental characteristics, and forest productivity were studied in the boreal forest in the North Klondike River Valley, Yukon Territory, Canada. The concept and approach of biogeoclimatic ecosystem classification were followed. For the treed vegetation, five ecosystem types were distinguished based on vegetation structure and physical and chemical properties of soils. They were: 1) spruce-lichen type, 2) spruce-moss type, 3) spruce-Equisetum type, 4) spruce-willow type, and 5) bog forest type. These types were differentiated mainly by moisture regime and base status of soils. The sequence of the ecosystem types reflected their topographical position from slope summit to valley bottom. The spruce-lichen type developed in the driest and nutritionally impoverished habitats, the spruce-Equisetum type occurred in moist and nutritionally enriched sites, and the spruce-moss type was found in between them. The bog forest type occurred where peat had accumulated sufficiently to generate ombrotrophic conditions in habitats of high water table underlain with permafrost. The spruce-willow type developed along small creeks where substrates were very coarse. Tree growth characteristics were measured, except for the bog forest type that did not have trees over 5 m tall. Total volume of standing trees ranged from 29 to 582 m(3)/ha, with an overall mean of 216.9 m(3)/ha. The spruce-Equisetum type exhibited the highest figure, 413.5 m(3)/ha, while spruce-lichen type the lowest one, 87.7 m(3)/ha. Mean annual increment ranged from 0.15 to 2.66 m(3)/ha, with an overall mean of 1.10 m(3)/ha. A similar tendency was noted for all other forestry characteristics, i.e., the spruce-Equisetum type showed the highest productivity while the spruce-lichen type the lowest. This tendency was considered to be attributed to the availability of moisture and basic cations in soils. PMID:24198010

  5. Interaction Between Lakes and Terrestrial Ecosystem Dynamics in the Yukon River Floodplain, in Interior Alaska, USA

    NASA Astrophysics Data System (ADS)

    Patil, V.; Griffith, B.; Euskirchen, E. S.

    2012-12-01

    Lakes have been decreasing in size and abundance in boreal ecosystems around the world. However, while as many as 35% of lakes in parts of interior Alaska are smaller than they were 50 years ago, up to 20% of lakes in the same regions experience large annual and intra-annual fluctuations in area (flooding), which have been linked to climate patterns via winter snowpack densities and the timing of spring thaw. Lake drying and flooding regime may influence plant community dynamics (e.g. succession), productivity, nutrient availability, and respiration, and thereby affect the carbon sink strength of boreal lake-margin wetlands. Climate change is likely to amplify drying trends and alter flooding patterns simultaneously. Predicting the future dynamics of boreal wetland complexes therefore requires quantifying the effects of flooding and drying on ecosystem processes, and the relative importance of these two mechanisms. In this study, we test the following hypotheses: 1) Both drying trends and flooding regime significantly affect lake-margin productivity, composition, and C storage by affecting soil moisture and soil nutrient concentrations, 2) frequently flooding lakes are associated with elevated soil moisture and productivity, but reduced soil carbon and nitrogen content, due to the differential influence of moisture on photosynthesis and decomposition, while drying lakes should show opposite trends. This study was conducted in the Yukon Flats National Wildlife Refuge, located 150 miles north of Fairbanks Alaska. We measured aboveground biomass, aboveground net primary productivity (ANPP), and a suite of soil characteristics within 100m of the lakeshore at 16 lakes in 2011 and 2012. Soil measurements included soil moisture, peat depth, seasonal thaw depth, total soil carbon and nitrogen, and available inorganic nitrogen. We classified lakes as drying, frequently flooding, or stable using remotely sensed measurements of long term trends as well as annual & intra

  6. Assessment of boreal forest historical C dynamics in Yukon River Basin: relative roles of warming and fire regime change

    SciTech Connect

    Yuan, Fengming; Yi, Shuhua; McGuire, A. David; Johnson, Kristopher D; Liang, Jingjing; Harden, Jennifer; Kasischke, Eric S.; Kurz, Werner

    2012-01-01

    Carbon (C) dynamics of boreal forest ecosystems have substantial implications for efforts to mitigate the rise of atmospheric CO2 and may be substantially influenced by warming and changing wildfire regimes. In this study we applied a large-scale ecosystem model that included dynamics of organic soil horizons and soil organic matter characteristics of multiple pools to assess forest C stock changes of the Yukon River Basin (YRB) in Alaska, USA, and Canada from 1960 through 2006, a period characterized by substantial climate warming and increases in wildfire. The model was calibrated for major forests with data from long-term research sites and evaluated using a forest inventory database. The regional assessment indicates that forest vegetation C storage increased by 46 Tg C, but that total soil C storage did not change appreciably during this period. However, further analysis suggests that C has been continuously lost from the mineral soil horizon since warming began in the 1970s, but has increased in the amorphous organic soil horizon. Based on a factorial experiment, soil C stocks would have increased by 158 Tg C if the YRB had not undergone warming and changes in fire regime. The analysis also identified that warming and changes in fire regime were approximately equivalent in their effects on soil C storage, and interactions between these two suggests that the loss of organic horizon thickness associated with increases in wildfire made deeper soil C stocks more vulnerable to loss via decomposition. Subbasin analyses indicate that C stock changes were primarily sensitive to the fraction of burned forest area within each subbasin and that boreal forest ecosystems in the YRB are currently transitioning from being sinks to sources at ;0.7% annual area burned. We conclude that it is important for international mitigation efforts focused on controlling atmospheric CO2 to consider how climate warming and changes in fire regime may concurrently affect the CO2 sink

  7. Assessment of boreal forest historical C dynamics in the Yukon River Basin: relative roles of warming and fire regime change

    USGS Publications Warehouse

    Yuan, F.M.; Yi, S.H.; McGuire, A.D.; Johnson, K.D.; Liang, J.; Harden, J.W.; Kasischke, E.S.; Kurz, W.A.

    2012-01-01

    Carbon (C) dynamics of boreal forest ecosystems have substantial implications for efforts to mitigate the rise of atmospheric CO2 and may be substantially influenced by warming and changing wildfire regimes. In this study we applied a large-scale ecosystem model that included dynamics of organic soil horizons and soil organic matter characteristics of multiple pools to assess forest C stock changes of the Yukon River Basin (YRB) in Alaska, USA, and Canada from 1960 through 2006, a period characterized by substantial climate warming and increases in wildfire. The model was calibrated for major forests with data from long-term research sites and evaluated using a forest inventory database. The regional assessment indicates that forest vegetation C storage increased by 46 Tg C, but that total soil C storage did not change appreciably during this period. However, further analysis suggests that C has been continuously lost from the mineral soil horizon since warming began in the 1970s, but has increased in the amorphous organic soil horizon. Based on a factorial experiment, soil C stocks would have increased by 158 Tg C if the YRB had not undergone warming and changes in fire regime. The analysis also identified that warming and changes in fire regime were approximately equivalent in their effects on soil C storage, and interactions between these two suggests that the loss of organic horizon thickness associated with increases in wildfire made deeper soil C stocks more vulnerable to loss via decomposition. Subbasin analyses indicate that C stock changes were primarily sensitive to the fraction of burned forest area within each subbasin and that boreal forest ecosystems in the YRB are currently transitioning from being sinks to sources at ∼0.7% annual area burned. We conclude that it is important for international mitigation efforts focused on controlling atmospheric CO2 to consider how climate warming and changes in fire regime may concurrently affect the CO2 sink

  8. Alaskan oceanography

    NASA Astrophysics Data System (ADS)

    Physical oceanographers, chemists, and biologists will soon begin studying the seas around northern Alaska as part of an international effort to learn how increased fishing, oil and gas drilling, and land-based farming will affect marine life. The $2.5 million National Science Foundation (NSF)- funded study, called ISHTAR (Inner Shelf Transfer and Recycling in the Bering and Chukchi Seas), will involve scientists from the United States, Belgium, and Denmark.According to NSF, previous studies suggest that, despite a short growing season, the seas around the Bering Strait produce more plant life than most marine areas of the world. However, the source of mineral nutrients for this plant life and its destination in the food web or organic sediment is not well understood. The researchers will trace nutrients from the Yukon River and the deeper waters of the Bering Sea to the continental shelves of the Bering and Chukchi seas in an attempt to better understand what happens to land and marine organic matter when it enters this continental shelf ecosystem.

  9. PCR testing can be as accurate as culture for diagnosis of Ichthyophonus hoferi in Yukon River Chinook salmon Oncorhynchus tshawytscha .

    PubMed

    Hamazaki, Toshihide; Kahler, Eryn; Borba, Bonnie M; Burton, Tamara

    2013-07-01

    We evaluated the comparability of culture and PCR tests for detecting Ichthyophonus in Yukon River Chinook salmon Oncorhynchus tshawytscha from field samples collected at 3 locations (Emmonak, Chena, and Salcha, Alaska, USA) in 2004, 2005, and 2006. Assuming diagnosis by culture as the 'true' infection status, we calculated the sensitivity (correctly identifying fish positive for Ichthyophonus), specificity (correctly identifying fish negative for Ichthyophonus), and accuracy (correctly identifying both positive and negative fish) of PCR. Regardless of sampling locations and years, sensitivity, specificity, and accuracy exceeded 90%. Estimates of infection prevalence by PCR were similar to those by culture, except for Salcha 2005, where prevalence by PCR was significantly higher than that by culture (p < 0.0001). These results show that the PCR test is comparable to the culture test for diagnosing Ichthyophonus infection. PMID:23836767

  10. Novel insights from NMR spectroscopy into seasonal changes in the composition of dissolved organic matter exported to the Bering Sea by the Yukon River

    USGS Publications Warehouse

    Cao, Xiaoyan; Aiken, George R.; Spencer, Robert G. M.; Butler, Kenna; Mao, Jingdong; Schmidt-Rohr, Klaus

    2016-01-01

    Seasonal (spring freshet, summer–autumn, and winter) variability in the chemical composition of dissolved organic matter (DOM) from the Yukon River was determined using advanced one- and two-dimensional (2D) solid-state NMR spectroscopy, coupled with isotopic measurements and UV–visible spectroscopy. Analyses were performed on two major DOM fractions, the hydrophobic organic acid (HPOA) and transphilic organic acid (TPIA) fractions obtained using XAD resins. Together these two fractions comprised 64–74% of the total DOM. Carboxyl-rich alicyclic molecules (CRAM) accounted for the majority of carbon atoms in the HPOA (63–77%) and TPIA (54–78%) samples, and more so in winter and summer than in spring samples. 2D and selective NMR data revealed association of abundant nonprotonated O-alkyl and quaternary alkyl C (OCnp, OCnpO and Cq, 13–17% of HPOA and 15–20% of TPIA) and isolated O–CH structures with CRAM, which were not recognized in previous studies. Spectral editing and 2D NMR allowed for the discrimination of carbohydrate-like O-alkyl C from non-carbohydrate O-alkyl C. Whereas two spring freshet TPIA samples contained carbohydrate clusters such as carboxylated carbohydrates (16% and 26%), TPIA samples from other seasons or HPOA samples mostly had small amounts (<8%) of sugar rings dispersed in a nonpolar alkyl environment. Though nonprotonated aromatic C represented the largest fraction of aromatic C in all HPOA/TPIA isolates, only a small fraction (∼5% in HPOA and 3% in TPIA) was possibly associated with dissolved black carbon. Our results imply a relatively stable portion of DOM exported by the Yukon River across different seasons, due to the predominance of CRAM and their associated nonprotonated C–O and O–C–O structures, and elevated reactivity (bio- and photo-lability) of spring DOM due to the presence of terrestrial inputs enriched in carbohydrates and aromatic structures.

  11. Novel insights from NMR spectroscopy into seasonal changes in the composition of dissolved organic matter exported to the Bering Sea by the Yukon River

    NASA Astrophysics Data System (ADS)

    Cao, Xiaoyan; Aiken, George R.; Spencer, Robert G. M.; Butler, Kenna; Mao, Jingdong; Schmidt-Rohr, Klaus

    2016-05-01

    Seasonal (spring freshet, summer-autumn, and winter) variability in the chemical composition of dissolved organic matter (DOM) from the Yukon River was determined using advanced one- and two-dimensional (2D) solid-state NMR spectroscopy, coupled with isotopic measurements and UV-visible spectroscopy. Analyses were performed on two major DOM fractions, the hydrophobic organic acid (HPOA) and transphilic organic acid (TPIA) fractions obtained using XAD resins. Together these two fractions comprised 64-74% of the total DOM. Carboxyl-rich alicyclic molecules (CRAM) accounted for the majority of carbon atoms in the HPOA (63-77%) and TPIA (54-78%) samples, and more so in winter and summer than in spring samples. 2D and selective NMR data revealed association of abundant nonprotonated O-alkyl and quaternary alkyl C (OCnp, OCnpO and Cq, 13-17% of HPOA and 15-20% of TPIA) and isolated O-CH structures with CRAM, which were not recognized in previous studies. Spectral editing and 2D NMR allowed for the discrimination of carbohydrate-like O-alkyl C from non-carbohydrate O-alkyl C. Whereas two spring freshet TPIA samples contained carbohydrate clusters such as carboxylated carbohydrates (16% and 26%), TPIA samples from other seasons or HPOA samples mostly had small amounts (<8%) of sugar rings dispersed in a nonpolar alkyl environment. Though nonprotonated aromatic C represented the largest fraction of aromatic C in all HPOA/TPIA isolates, only a small fraction (∼5% in HPOA and 3% in TPIA) was possibly associated with dissolved black carbon. Our results imply a relatively stable portion of DOM exported by the Yukon River across different seasons, due to the predominance of CRAM and their associated nonprotonated C-O and O-C-O structures, and elevated reactivity (bio- and photo-lability) of spring DOM due to the presence of terrestrial inputs enriched in carbohydrates and aromatic structures.

  12. Integrating modelling and remote sensing to identify ecosystem performance anomalies in the boreal forest, Yukon River Basin, Alaska

    USGS Publications Warehouse

    Wylie, B.K.; Zhang, L.; Bliss, Norman B.; Ji, Lei; Tieszen, Larry L.; Jolly, W. M.

    2008-01-01

    High-latitude ecosystems are exposed to more pronounced warming effects than other parts of the globe. We develop a technique to monitor ecological changes in a way that distinguishes climate influences from disturbances. In this study, we account for climatic influences on Alaskan boreal forest performance with a data-driven model. We defined ecosystem performance anomalies (EPA) using the residuals of the model and made annual maps of EPA. Most areas (88%) did not have anomalous ecosystem performance for at least 6 of 8 years between 1996 and 2004. Areas with underperforming EPA (10%) often indicate areas associated with recent fires and areas of possible insect infestation or drying soil related to permafrost degradation. Overperforming areas (2%) occurred in older fire recovery areas where increased deciduous vegetation components are expected. The EPA measure was validated with composite burn index data and Landsat vegetation indices near and within burned areas.

  13. Defining biophysical reference conditions for dynamics river systems: an Alaskan example

    NASA Astrophysics Data System (ADS)

    Pess, G. R.

    2008-12-01

    Defining reference conditions for dynamic river ecosystems is difficult for two reasons. First long-term, persistent anthropogenic influences such as land development, harvest of biological resources, and invasive species have resulted in degraded, reduced, and simplified ecological communities and associated habitats. Second, river systems that have not been altered through human disturbance rarely have a long-term dataset on ecological conditions. However there are exceptions which can help us define the dynamic nature of river ecosystems. One large-scale exception is the Wood River system in Bristol Bay, Alaska, where habitat and salmon populations have not been altered by anthropogenic influences such as land development, hatchery production, and invasive species. In addition, the one major anthropogenic disturbance, salmon (Oncorhynchus spp.) harvest, has been quantified and regulated since its inception. First, we examined the variation in watershed and stream habitat characteristics across the Wood River system. We then compared these stream habitat characteristics with data that was collected in the 1950s. Lastly, we examined the correlation between pink (Oncorhynchus gorbuscha), chum (O. keta), and Chinook (O. tshawytscha), and sockeye salmon (O. nerka), and habitat characteristics in the Wood River system using four decades of data on salmon. We found that specific habitat attributes such as stream channel wetted width, depth, cover type, and the proportion of spawnable area were similar to data collected in the 1950s. Greater stream habitat variation occurred among streams than over time. Salmon occurrence and abundance, however was more temporal and spatially variable. The occurrence of pink and chum salmon increased from the 1970's to the present in the Wood River system, while sockeye abundance has fluctuated with changes in ocean conditions. Pink, Chinook and chum salmon ranged from non-existent to episodic to abundantly perennial, while sockeye

  14. The Mackenzie River magnetic anomaly, Yukon and Northwest Territories, Canada-Evidence for Early Proterozoic magmatic arc crust at the edge of the North American craton

    USGS Publications Warehouse

    Pilkington, M.; Saltus, R.W.

    2009-01-01

    We characterize the nature of the source of the high-amplitude, long-wavelength, Mackenzie River magnetic anomaly (MRA), Yukon and Northwest Territories, Canada, based on magnetic field data collected at three different altitudes: 300??m, 3.5??km and 400??km. The MRA is the largest amplitude (13??nT) satellite magnetic anomaly over Canada. Within the extent of the MRA, source depth estimates (8-12??km) from Euler deconvolution of low-altitude aeromagnetic data show coincidence with basement depths interpreted from reflection seismic data. Inversion of high-altitude (3.5??km) aeromagnetic data produces an average magnetization of 2.5??A/m within a 15- to 35-km deep layer, a value typical of magmatic arc complexes. Early Proterozoic magmatic arc rocks have been sampled to the southeast of the MRA, within the Fort Simpson magnetic anomaly. The MRA is one of several broad-scale magnetic highs that occur along the inboard margin of the Cordillera in Canada and Alaska, which are coincident with geometric changes in the thrust front transition from the mobile belt to stable cratonic North America. The inferred early Proterozoic magmatic arc complex along the western edge of the North American craton likely influenced later tectonic evolution, by acting as a buttress along the inboard margin of the Cordilleran fold-and-thrust belt. Crown Copyright ?? 2008.

  15. Tephrochronology, magnetostratigraphy and mammalian faunas of Middle and Early Pleistocene sediments at two sites on the Old Crow River, northern Yukon Territory, Canada

    NASA Astrophysics Data System (ADS)

    Westgate, John A.; Pearce, G. William; Preece, Shari J.; Schweger, Charles E.; Morlan, Richard E.; Pearce, Nicholas J. G.; Perkins, T. William

    2013-01-01

    Alluvial and lacustrine sediments exposed beneath late Pleistocene glaciolacustrine silt and clay at two sites along the Old Crow River, northern Yukon Territory, are rich in fossils and contain tephra beds. Surprise Creek tephra (SZt) occurs in the lower part of the alluvial sequence at CRH47 and Little Timber tephra (LTt) is present near the base of the exposure at CRH94. Surprise Creek tephra has a glass fission-track age of 0.17 ± 0.07 Ma and Little Timber tephra is 1.37 ± 0.12 Ma. All sediments at CRH47 have a normal remanent magnetic polarity and those near LTt at CRH94 have a reversed polarity — in agreement with the geomagnetic time scale. Small mammal remains from sediments near LTt support an Early Pleistocene age but the chronology is not so clear at CRH47 because of the large error associated with the SZt age determination. Tephrochronological and paleomagnetic considerations point to an MIS 7 age for the interglacial beds just below SZt at CRH47 and at Chester Bluffs in east-central Alaska, but mammalian fossils recovered from sediments close to SZt suggest a late Irvingtonian age, therefore older than MIS 7. Further studies are needed to resolve this problem.

  16. Recent physical connections may explain weak genetic structure in western Alaskan chum salmon (Oncorhynchus keta) populations.

    PubMed

    Garvin, Michael R; Kondzela, Christine M; Martin, Patrick C; Finney, Bruce; Guyon, Jeffrey; Templin, William D; Decovich, Nick; Gilk-Baumer, Sara; Gharrett, Anthony J

    2013-07-01

    Low genetic divergence at neutral loci among populations is often the result of high levels of contemporary gene flow. Western Alaskan summer-run chum salmon (Oncorhynchus keta) populations demonstrate weak genetic structure, but invoking contemporary gene flow as the basis for the low divergence is problematic because salmon home to their natal streams and some of the populations are thousands of kilometers apart. We used genotypes from microsatellite and single nucleotide polymorphism loci to investigate alternative explanations for the current genetic structure of chum salmon populations from western Alaska. We also estimated current levels of gene flow among Kuskokwim River populations. Our results suggest that weak genetic structure is best explained by physical connections that occurred after the Holocene Thermal Maximum among the Yukon, Kuskokwim, and Nushagak drainages that allowed gene flow to occur among now distant populations. PMID:23919176

  17. Recent physical connections may explain weak genetic structure in western Alaskan chum salmon (Oncorhynchus keta) populations

    PubMed Central

    Garvin, Michael R; Kondzela, Christine M; Martin, Patrick C; Finney, Bruce; Guyon, Jeffrey; Templin, William D; DeCovich, Nick; Gilk-Baumer, Sara; Gharrett, Anthony J

    2013-01-01

    Low genetic divergence at neutral loci among populations is often the result of high levels of contemporary gene flow. Western Alaskan summer-run chum salmon (Oncorhynchus keta) populations demonstrate weak genetic structure, but invoking contemporary gene flow as the basis for the low divergence is problematic because salmon home to their natal streams and some of the populations are thousands of kilometers apart. We used genotypes from microsatellite and single nucleotide polymorphism loci to investigate alternative explanations for the current genetic structure of chum salmon populations from western Alaska. We also estimated current levels of gene flow among Kuskokwim River populations. Our results suggest that weak genetic structure is best explained by physical connections that occurred after the Holocene Thermal Maximum among the Yukon, Kuskokwim, and Nushagak drainages that allowed gene flow to occur among now distant populations. PMID:23919176

  18. Major element concentrations in six Alaskan arctic rivers from melt to freeze-up

    NASA Astrophysics Data System (ADS)

    Douglas, T. A.; Barker, A.; Jacobson, A. D.; McClelland, J. W.; Khosh, M. S.; Lehn, G. O.

    2010-12-01

    It is increasingly evident that permafrost in the Arctic is responding to climate warming. An expected response to this warming is permafrost degradation and the downward migration of the seasonally thawed (active) layer into previously frozen material. This could allow weathering of previously frozen soils and influence surface water biogeochemistry in Arctic rivers. The weathering signal would most likely be evident in surface waters during summer and early fall base flow when the active layer is at its deepest extent. Studies collecting water samples from spring through late fall could capture these flows. Fieldwork in remote regions often requires long storage times for samples prior to analysis. One aspect of our study was to investigate whether waters collected for major element analyses should be preserved by acidification. We collected up to 60 surface water samples from each of six rivers between April and October, 2009. Two rivers were underlain by organic rich permafrost, two of the rivers drained mountainous bedrock, and two rivers were underlain by a combination of both bedrock and organic rich permafrost. We collected duplicate samples from each river. Samples were filtered in the field to less than 0.45 microns and collected into high density polyethylene bottles. Waters were stored for six months prior to analysis. One set of samples was analyzed without acidification while the second set was acidified with nitric acid to a pH of 2 after 6 months of storage. Concentrations of sodium, potassium, magnesium, calcium, ammonium, fluoride, chloride, nitrate, sulfate and phosphate were measured from all samples by ion chromatography. Sulfate, calcium, magnesium, sodium and potassium concentrations increase steadily through the summer from the end of spring melt into early fall. In all six rivers the potassium concentrations are unaffected by acidification. In the two streams underlain by organic rich permafrost and in one of the bedrock streams the calcium

  19. Alaskan Voices.

    ERIC Educational Resources Information Center

    Achatz, Mary, Ed.; Caldera, Debra, Ed.; Saylor, Brian; DeGross, Denny

    This paper examines the attitudes of adults and teenagers in 10 predominantly rural Alaskan communities toward their own health and well-being and that of children and families in their community. The communities were located across the state and ranged in size from populations of under 900 to over 50,000. The proportion of Alaska Natives in the…

  20. Use of a portable electric barrier to estimate Chinook salmon escapement in a turbid Alaskan river

    USGS Publications Warehouse

    Palmisano, A.; Burger, C.V.

    1988-01-01

    We developed a portable electric barrier to aid in the capture of adult chinook salmon Oncorhynchus tshawytscha undergoing spawning migrations up a turbid stream in south-central Alaska. In 1981, we tagged and released 157 chinook salmon after diverting them from the main-stem Killey River into a conventional trap with the aid of the electric barrier. On the basis of returns of tagged salmon to Benjamin Creek, a clear-water tributary of the upper Killey River, we estimated spawners in the drainage to number 8,000 fish. Two different statistical approaches to the mark–recapture data yielded similar estimates. Through several modifications of the electric barrier, we were able to reduce mortality associated with the barrier's use.

  1. Seasonal dynamics of particulate organic carbon and nitrogen in Alaskan Arctic streams and rivers

    NASA Astrophysics Data System (ADS)

    Khosh, M. S.; McClelland, J. W.; Jacobson, A. D.; Douglas, T. A.; Lehn, G. O.; Barker, A. J.

    2012-12-01

    The impacts of Arctic climate warming include an accelerated hydrological cycle, longer snow and ice free seasons, and wide-scale permafrost degradation. Such changes will alter the quantity, seasonality, and flow paths of water in Arctic river catchments. Biogeochemical processes will be impacted, with responses becoming apparent during an earlier spring melt transition from winter to summer, and in the later summer to early fall when the extent of the seasonally thawed active layer reaches its maximum depth. While knowledge of the seasonal dynamics of water-borne constituents in Arctic rivers is improving, the shoulder seasons of spring and fall to early winter, have historically been times of the year that Arctic rivers have been under sampled. This presentation will focus on characterizing the seasonality of particulate organic carbon (POC) and particulate organic nitrogen (PON) concentrations and composition, using bulk measurements and stable isotope ratios (δ13C and δ15N), with a major emphasis placed on high resolution sampling during the periods of spring snowmelt and late summer until fall freeze-up. Between May and October of 2009 we collected surface water samples from 6 different rivers underlain by continuous permafrost in the vicinity of Toolik Field Station on the North Slope of Alaska's Brooks Range, with catchment sizes ranging from 1.6 km2 to 610 km2. Three rivers drain low-gradient tussock tundra landscape, while the other three rivers are within high-gradient mountainous terrain, draining predominantly exposed bedrock. At both tundra and mountain sites, POC and PON concentrations show markedly similar patterns qualitatively and quantitatively. Concentrations are highest during the spring snowmelt and decline throughout the summer with the lowest values observed during the fall. At both tundra and mountain sites, POC stable isotope ratios are highest during the spring, reach minima during the summer, and then increase slightly in the fall. PON

  2. A retrospective on hydroacoustic assessment of fish passage in Alaskan rivers

    NASA Astrophysics Data System (ADS)

    Burwen, Debby; Fleischman, Steve; Maxwell, Suzanne; Pfisterer, Carl

    2005-04-01

    The Alaska Department of Fish and Game (ADFG) has enumerated fish stocks in rivers for over 30 years using a variety of acoustic technologies including single-, dual-, and split-beam sonar. Most recently, ADFG has evaluated a relatively new sonar technology at several sites in Alaska to determine its applicability to counting migrating fish in rivers. The new system, called a Dual frequency IDentification SONar (DIDSON), is a high-definition imaging sonar designed and manufactured by the University of Washington's Applied Physics Lab for military applications such as diver detection and underwater mine identification. Results from experiments conducted in 2002-2004 indicate that DIDSON provides significant improvements in our ability to detect, track, and determine the direction of travel of migrating fish in rivers. One of the most powerful uses of the DIDSON has been to combine its camera-like images of fish swimming behavior with corresponding split-beam data. These linked datasets have allowed us to evaluate the effects of fish orientation and swimming behavior on echo shape parameters that have proven useful in the classification of certain fish species.

  3. Patterns of shrub expansion in Alaskan arctic river corridors suggest phase transition

    PubMed Central

    Naito, Adam T; Cairns, David M

    2015-01-01

    Recent increases in deciduous shrub cover are a primary focus of terrestrial Arctic research. This study examined the historic spatial patterns of shrub expansion on the North Slope of Alaska to determine the potential for a phase transition from tundra to shrubland. We examined the historic variability of landscape-scale tall shrub expansion patterns on nine sites within river valleys in the Brooks Range and North Slope uplands (BRNS) between the 1950s and circa 2010 by calculating percent cover (PCTCOV), patch density (PADENS), patch size variability (CVSIZE), mean nearest neighbor distance (MEDIST) and the multi-scale information fractal dimension (dI) to assess spatial homogeneity for shrub cover. We also devised conceptual models for trends in these metrics before, during, and after a phase transition, and compared these to our results. By developing a regression equation between PCTCOV and dI and using universal critical dI values, we derived the PCTCOV required for a phase transition to occur. All nine sites exhibited increases in PCTCOV. Five of the nine sites exhibited an increase in PADENS, seven exhibited an increase in CVSIZE, and five exhibited a decrease in MEDIST. The dI values for each site exceeded the requirements necessary for a phase transition. Although fine-scale heterogeneity is still present, landscape-scale patterns suggest our study areas are either currently in a state of phase transition from tundra to shrubland or are progressing towards spatial homogeneity for shrubland. Our results indicate that the shrub tundra in the river valleys of the north slope of Alaska has reached a tipping point. If climate trends observed in recent decades continue, the shrub tundra will continue towards homogeneity with regard to the cover of tall shrubs. PMID:25628866

  4. DNA and allozyme markers provide concordant estimates of population differentiation: Analyses of U.S. and Canadian populations of Yukon River fall-run chum salmon (Oncorhynchus keta)

    USGS Publications Warehouse

    Scribner, K.T.; Crane, P.A.; Spearman, W.J.; Seeb, L.W.

    1998-01-01

    Although the number of genetic markers available for fisheries research has steadily increased in recent years, there is limited information on their relative utility. In this study, we compared the performance of different 'classes' of genetic markers (mitochondrial DNA (mtDNA), nuclear DNA (nDNA), and allozymes) in terms of estimating levels and partitioning of genetic variation and of the relative accuracy and precision in estimating population allocations to mixed-stock fisheries. Individuals from eight populations of fall-run chum salmon (Oncorhynchus keta) from the Yukon River in Alaska and Canada were assayed at 25 loci. Significant differences in mitochondrial haplotype and nuclear allele frequencies were observed among five drainages. Populations from the U.S.-Canada border region were not clearly distinguishable based on multilocus allele frequencies. Although estimates of total genetic diversities were higher for the DNA loci (H(t) = 0.592 and h = 0.647 for nDNA and mtDNA, respectively) compared with protein allozymes (H(t) = 0.250), estimates of the extent of population differentiation were highly concordant across marker classes (mean ?? = 0.010, 0.011, and 0.016 for allozymes, nDNA, and mtDNA, respectively). Simulations of mixed-stock fisheries composed of varying contributions of U.S. and Canadian populations revealed a consistent bias for overallocation of Canadian stocks when expected Canadian contributions varied from 0 to 40%, due primarily to misallocations among genetically similar border populations. No single marker class is superior for differentiating populations of this species at the spatial scale examined.

  5. Sea, ice and surface water circulation, Alaskan continental shelf

    NASA Technical Reports Server (NTRS)

    Wright, F. F.; Sharma, G. D.; Burns, J. J. (Principal Investigator)

    1973-01-01

    The author has identified the following significant results. Salinity and temperature measurements in the Bering Sea indicate that the Yukon River outflow extends as far as 200 km from its mouth. The fresh water flow from the Yukon River flows north and east into Norton Sound. Various levels of suspended sediment concentration in waters have been successfully color coded using a VP-8 color density slicing image analyzer. The 70 mm negative transparencies have provided the best fit for the ground truth observations.

  6. Stratiform zinc-lead mineralization in Nasina assemblage rocks of the Yukon-Tanana Upland in east-central Alaska

    USGS Publications Warehouse

    Dusel-Bacon, Cynthia; Bressler, Jason R.; Takaoka, Hidetoshi; Mortensen, James K.; Oliver, Douglas H.; Leventhal, Joel S.; Newberry, Rainer J.; Bundtzen, Thomas K.

    1998-01-01

    The Yukon-Tanana Upland of east-central Alaska and Yukon comprises thrust sheets of ductilely deformed metasedimentary and metaigneous rocks of uncertain age and origin that are overlain by klippen of weakly metamorphosed oceanic rocks of the Seventymile-Slide Mountain terrane, and intruded by post-kinematic Early Jurassic, Cretaceous and Tertiary granitoids. Metamorphosed continental margin strata in the Yukon-Tanana Upland of east-central Alaska are thought to be correlative, on the basis of stratigraphic similarities and sparse Mississippian U-Pb zircon and fossil ages (Mortensen, 1992), with middle Paleozoic metasedimentary and metavolcanic rocks in the eastern Alaska Range and in western and southeastern Yukon. Furthermore, rocks in the northern Yukon-Tanana Upland may correlate across the Tintina fault with unmetamorphosed counterparts in the Selwyn Basin (Murphy and Abbott, 1995). Volcanic-hosted (VMS) and sedimentary exhalative (sedex) massive sulfide occurrences are widely reported for these other areas (green-colored unit of fig. 1) but, as yet, have not been documented in the Alaskan part of the Yukon-Tanana Upland. Recent discoveries of VMS deposits in Devono-Mississippian metavolcanic rocks in the Finlayson Lake area of southeastern Yukon (Hunt, 1997) have increased the potential for finding VMS deposits in rocks of similar lithology and age in the Yukon-Tanana Upland of Alaska. Restoration of 450 km of early Tertiary dextral movement along the Tintina fault juxtaposes these two areas.

  7. Binding and transport of rare earth elements by organic and iron-rich nanocolloids in Alaskan rivers, as revealed by field-flow fractionation and ICP-MS

    NASA Astrophysics Data System (ADS)

    Stolpe, Björn; Guo, Laodong; Shiller, Alan M.

    2013-04-01

    Water samples were collected from six small rivers in the Yukon River basin in central Alaska to examine the role of nanocolloids (0.5-40 nm) in the dynamics and transport of rare earth elements (REEs) in northern high latitude watersheds influenced by permafrost. Total dissolved (<0.45 μm) concentrations and the 'nanocolloidal size distributions' (0.5-40 nm) of UV-absorbing dissolved organic matter, Fe, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu were determined by on-line coupling of flow field-flow fractionation (FFF) with a UV-absorbance detector and ICP-MS. Total dissolved and nanocolloidal concentrations of the REEs co-varied with dissolved organic carbon (DOC) in all rivers and between spring flood and late summer baseflow. The nanocolloidal size distributions indicated the presence of three major components of nanocolloids: the 0.5-3 nm 'fulvic-rich nanocolloids' occurring throughout the sampling season, the 'organic/iron-rich nanocolloids' residing in the <8 nm size range during the spring flood, and the 4-40 nm iron-rich nanocolloids occurring during summer baseflow. REEs associated with all the three components of nanocolloids, but the proportions associated with the fulvic-rich nanocolloids during summer baseflow increased with increasing REE molar mass, which is consistent with the increase in stability of organic REE-complexes with increasing REE molar mass. Normalization of the measured REE-concentrations with the average REE-concentrations of the upper continental crust revealed a dynamic change in the physicochemical fractionation of REEs. During the spring flood, REE-binding in all the rivers was dominated by the <8 nm organic/iron-rich nanocolloids, likely being eroded from the upper organic-rich soil horizon by the strong surface runoff of snowmelt water. During the summer, the REE-binding in rivers with large groundwater input was dominated by small (<0.5 nm) organic and/or inorganic complexes, while lower proportions of the REEs

  8. Communicating Risk and Cultivating Resilience in Rural Alaskan Communities: A Multi-Disciplinary Approach to Flood Mitigation

    NASA Astrophysics Data System (ADS)

    Kontar, Y. Y.

    2014-12-01

    The increasing extent and vulnerability of technologically advanced society together with aspects of global climate change intensifies the frequency and severity of natural disasters. Every year, communities around the world face the devastating consequences of hazardous events, including loss of life, property and infrastructure damage, and environmental decline. Environmentally sound strategies have to be developed to minimize these consequences. However, hazard-prone areas differ geographically, climatically, and culturally. There is no a one-size-fits-all solution. Thus, it is crucial that future decision-makers not only know the conditions that make some natural Earth processes hazardous to people, but also understand how people perceive and adjust to potential natural hazards in their regions. In May 2013, an ice jam caused major flooding in Galena, a remote village in interior Alaska. Within two days, flooding destroyed nearly the entire region's infrastructure, and displaced over 400 residents. Almost a year later, a significant part of Galena's population was still evacuated in Fairbanks and other neighboring towns. The rebuilding holdup reflected the federal government's reluctance to spend millions of dollars an the area that may be destroyed again by the next flood. Massive floods inundated towns along the Yukon River before (e.g., Eagle in 2009 and Holycross in 1975), but people return to refurbish and again inhabit the same territories. Rivers have a significant importance to Alaskan rural communities. Not only do rivers provide food, drink, transportation, and in some cases arable land and irrigation, but they also carry cultural significance for the Native Alaskan people. The Galena case study provides a revealing example of challenges of communicating with and educating the public and policy makers about natural hazards.

  9. Relationships between ecosystem metabolism, benthic macroinvertebrate densities, and environmental variables in a sub-arctic Alaskan river

    USGS Publications Warehouse

    Benson, Emily R.; Wipfli, Mark S.; Clapcott, Joanne E.; Hughes, Nicholas F.

    2013-01-01

    Relationships between environmental variables, ecosystem metabolism, and benthos are not well understood in sub-arctic ecosystems. The goal of this study was to investigate environmental drivers of river ecosystem metabolism and macroinvertebrate density in a sub-arctic river. We estimated primary production and respiration rates, sampled benthic macroinvertebrates, and monitored light intensity, discharge rate, and nutrient concentrations in the Chena River, interior Alaska, over two summers. We employed Random Forests models to identify predictor variables for metabolism rates and benthic macroinvertebrate density and biomass, and calculated Spearman correlations between in-stream nutrient levels and metabolism rates. Models indicated that discharge and length of time between high water events were the most important factors measured for predicting metabolism rates. Discharge was the most important variable for predicting benthic macroinvertebrate density and biomass. Primary production rate peaked at intermediate discharge, respiration rate was lowest at the greatest time since last high water event, and benthic macroinvertebrate density was lowest at high discharge rates. The ratio of dissolved inorganic nitrogen to soluble reactive phosphorus ranged from 27:1 to 172:1. We found that discharge plays a key role in regulating stream ecosystem metabolism, but that low phosphorous levels also likely limit primary production in this sub-arctic stream.

  10. The Beaver River structure: A cross-strike discontinuity of possible crustal dimensions in the southern Mackenzie Fold Belt, Yukon and Northwest territories, Canada

    USGS Publications Warehouse

    Morrow, D.W.; Miles, W.C.

    2000-01-01

    A significant cross-strike structural discontinuity, the Beaver River Structure, has been recognized near the boundary between the north-central part of the Mackenzie Fold Belt and its southern part, the Liard Plateau. The Beaver River Structure is the northeast continuation of the Beaver Fault toward the confluence of the South Nahanni and Liard rivers and into the Interior Platform. It is oriented sub-parallel with the Liard Line farther south. Cumulative Laramide-aged dextral movement of 10 to 20 kilometres is inferred to have occurred along the Beaver River Structure. Small dextral offsets occur along the Beaver Fault, a possible surface manifestation of the Beaver River Structure and large, dominantly north-south oriented Laramide-aged folds and faults, such as the Kotaneelee and Liard synclines and the Nahanni Thrust Fault appear to have been locally rotated in a manner consistent with dextral strike-slip of at least 10 to 20 kilometres. The absence of Permian and Triassic strata in the Mackenzie Fold Belt north of the Beaver River Structure may indicate that uplift and erosion occurred north of the Beaver River Structure during the Early Cretaceous Columbian Orogeny. It is likely that the Beaver River Structure is an ancient, possibly Precambrian, structure that has been reactivated several times throughout Phanerozoic time.

  11. Fort Yukon, Chalkyitsik, & Venetie Biomass Boiler Feasibility Study

    SciTech Connect

    Greg Koontz, ME William A. Wall, PhD

    2009-03-31

    The Council of Athabascan Tribal Governments (CATG) is a consortium of ten Gwich'in and Koyukon Athabascan tribes settled in 10 remote villages and are linked by the Yukon River System. The CATG mission is to maintain the Yukon Flats region as Indian Country by asserting traditional rights and taking responsibility for developing tribal technical capacity to manage the land and resources. It is the intent of CATG to explore and develop all opportunities for a renewable and self-sufficient energy program for each of the villages. CATG envisions utilization of forest resources both for construction and energy as one of the best long-term strategies for integrating the economic goals for the region as well as supporting the cultural and social issues. The intent for this feasibility project is to focus specifically on biomass utilization for heat, first, and for future electrical generation within the region, second. An initial determination has already been made regarding the importance of wood energy as a primary source of renewable energy to displace diesel fuel in the Yukon Flats region. A desktop study of other potential renewable resources was conducted in 2006.

  12. Changing the Organizational Paradigm: The Yukon Experience

    ERIC Educational Resources Information Center

    Sharp, Robert

    2011-01-01

    About 20 years ago, a number of Yukon schools took a different approach to outdoor education and outdoor pursuits. During the 1970s and 1980s, most Yukon high schools and junior high schools offered a course called Outdoor Education. These courses fit into the conventional blocks in a school timetable. Outdoor activities longer than these blocks…

  13. A 2,000-mile partnership with the USGS, Kayaks down the Yukon

    USGS Publications Warehouse

    Schuster, P.; Reddy, M.

    2003-01-01

    Early in 2001, Bill Barber and Jay Klinck, avid kayakers and scientists, began planning a northern expedition that would take them across more than 2,000 miles of mostly untamed wilderness along the Yukon River. At the same time, USGS scientists were making plans to study the last, unregulated great river in North America, spanning one of the largest and most diverse ecosystems in the world. Soon, the paths of kayakers and scientists would cross.

  14. Women and Minorities in Alaskan Aviation. Alaskan Equity Publication.

    ERIC Educational Resources Information Center

    Dordan, Mary Lou; Nicholson, Deborah

    This resource guide tells the story of Alaskan women and minority aviators and those in aviation-related businesses, from the early 20th century to the present. Developed for secondary students but also suitable for younger students, the guide combines six accounts of Alaskan women and minority aviators with classroom activities centered around…

  15. Productivity through Leadership Training in the Yukon

    ERIC Educational Resources Information Center

    Canadian Training Methods, 1976

    1976-01-01

    The TELOS program, which identifies a range of leadership behaviors for the decision-making process, was implemented at Cyprus Anvil Mines in the Yukon. Increased productivity and individual growth among the mine's senior management resulted. (MS)

  16. Three Years of CARVE-FTS Observations of CO2, CH4, and CO in the Alaskan Arctic: Status Quo and Comparison with Satellite Measurements

    NASA Astrophysics Data System (ADS)

    Kurosu, T. P.; Miller, C. E.; Dinardo, S. J.

    2014-12-01

    The Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE) is an aircraft-based Earth Venture 1 mission to study the carbon balance of the Alaskan Arctic ecosystem, with a particular focus on carbon release from melting permafrost. Operating from its base in Fairbanks, AK, the CARVE aircraft covers a range of principle flight paths in the Alaskan interior, the Yukon River valley, and the northern Alaska coast around Barrow and Dead Horse. Flight paths are chosen to maximize ecosystem variability and cover burn-recovery/regrowth sequences. CARVE observations cover the Arctic Spring/Summer/Fall seasons, with multiple flights per season and principle flight path. Science operations started in 05/2012 and are currently envisaged to continue until 2015. The CARVE suite of instruments includes flask measurements, in situ gas analyzers for CO2, CH4 and CO observations, and a three-band polarizing Fourier Transform Spectrometer (FTS) for column measurements of CO2, CH4, CO, their interfering species (e.g., H2O), and O2. The FTS covers the spectral regions of 4,200-4,900 cm-1 (CH4, CO), 5,800-6,400 cm-1 (CO2), and 12,900-13,200 cm-1 (O2), with a spectral resolution of 0.2 cm-1. Aircraft-based FTS science observations in Alaska have been performed since 23-05-2012. First-version data products from all CARVE instruments derived from observations during the 2012 campaign were publicly released earlier in 2013. The FTS has performed well during flight conditions, particularly with respect to vibration damping. We present results from FTS column observations of CO2, CH4, and CO, observed during the 2012, 2013, and 2014 campaigns, including comparisons of CARVE FTS measurements with satellite observations of CO2 from TANSO/GOSAT retrieved by JPL/ACOS, and MOPITT CO.

  17. Broadcasting and Telecommunications. Yukon 2000: A Communications Policy for the Yukon.

    ERIC Educational Resources Information Center

    Yukon Dept. of Community and Transportation, Whitehorse.

    This publication discusses the Yukon Territory government's role in communications matters at both the territorial and the national levels in Canada. The 10 sections of the report address the following topics: (1) the government's response to the demand of Yukoners for better communications services through the development of a territory-specific…

  18. Alaskan Commodities Irradiation Project

    SciTech Connect

    Zarling, J.P.; Swanson, R.B.; Logan, R.R.; Das, D.K.; Lewis, C.E.; Workman, W.G.; Tumeo, M.A.; Hok, C.I.; Birklid, C.A.; Bennett, F.L.

    1988-12-01

    The ninety-ninth US Congress commissioned a six-state food irradiation research and development program to evaluate the commercial potential of this technology. Hawaii, Washington, Iowa, Oklahoma and Florida as well as Alaska have participated in the national program; various food products including fishery products, red meats, tropical and citrus fruits and vegetables have been studied. The purpose of the Alaskan study was to review and evaluate those factors related to the technical and economic feasibility of an irradiator in Alaska. This options analysis study will serve as a basis for determining the state's further involvement in the development of food irradiation technology. 40 refs., 50 figs., 53 tabs.

  19. Abundance, size distributions and trace-element binding of organic and iron-rich nanocolloids in Alaskan rivers, as revealed by field-flow fractionation and ICP-MS

    NASA Astrophysics Data System (ADS)

    Stolpe, Björn; Guo, Laodong; Shiller, Alan M.; Aiken, George R.

    2013-03-01

    Water samples were collected from six small rivers in the Yukon River basin in central Alaska to examine the role of colloids and organic matter in the transport of trace elements in Northern high latitude watersheds influenced by permafrost. Concentrations of dissolved organic carbon (DOC), selected elements (Al, Si, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Rb, Sr, Ba, Pb, U), and UV-absorbance spectra were measured in 0.45 μm filtered samples. 'Nanocolloidal size distributions' (0.5-40 nm, hydrodynamic diameter) of humic-type and chromophoric dissolved organic matter (CDOM), Cr, Mn, Fe, Co, Ni, Cu, Zn, and Pb were determined by on-line coupling of flow field-flow fractionation (FFF) to detectors including UV-absorbance, fluorescence, and ICP-MS. Total dissolved and nanocolloidal concentrations of the elements varied considerably between the rivers and between spring flood and late summer base flow. Data on specific UV-absorbance (SUVA), spectral slopes, and the nanocolloidal fraction of the UV-absorbance indicated a decrease in aromaticity and size of CDOM from spring flood to late summer. The nanocolloidal size distributions indicated the presence of different 'components' of nanocolloids. 'Fulvic-rich nanocolloids' had a hydrodynamic diameter of 0.5-3 nm throughout the sampling season; 'organic/iron-rich nanocolloids' occurred in the <8 nm size range during the spring flood; whereas 'iron-rich nanocolloids' formed a discrete 4-40 nm components during summer base flow. Mn, Co, Ni, Cu and Zn were distributed between the nanocolloid components depending on the stability constant of the metal (+II)-organic complexes, while stronger association of Cr to the iron-rich nanocolloids was attributed to the higher oxidation states of Cr (+III or +IV). Changes in total dissolved element concentrations, size and composition of CDOM, and occurrence and size of organic/iron and iron-rich nanocolloids were related to variations in their sources from either the upper organic

  20. Geochemistry of saline lakes of the northeastern Yukon Flats, east central Alaska

    NASA Astrophysics Data System (ADS)

    Hawkins, D. B.

    1985-01-01

    Above the Arctic Circle in the Yukon Flats of northeastern Alaska, shallow, brackish water ponds are rimmed with evaporite minerals such as trona (NaHCO3Na2CO3). These ponds form in an area of Alaska characterized by an extreme continental climate with about six inches of precipitation annually. Evaporite formation occurs because evaporation exceeds inflow. The hydrogeochemistry of the waters of the Yukon Flats was investigated to determine the origin of the ponds and evaporite minerals. Evaporation of the freshwater lakes will first precpitate calcite and ultimately form trona. The change in relative concentrations of Ca(+2), HCO3, and SO4 in going from river water to lake water is critical and indicates that sulfate reduction accompanied by bicarbonate formation is an essential process that produces an excess of HCO3 over CA(+2).

  1. Alaskan North Slope petroleum systems

    USGS Publications Warehouse

    Magoon, L.B.; Lillis, P.G.; Bird, K.J.; Lampe, C.; Peters, K.E.

    2003-01-01

    Six North Slope petroleum systems are identified, described, and mapped using oil-to-oil and oil-to-source rock correlations, pods of active source rock, and overburden rock packages. To map these systems, we assumed that: a) petroleum source rocks contain 3.2 wt. % organic carbon (TOC); b) immature oil-prone source rocks have hydrogen indices (HI) >300 (mg HC/gm TOC); c) the top and bottom of the petroleum (oil plus gas) window occur at vitrinite reflectance values of 0.6 and 1.0% Ro, respectively; and d) most hydrocarbons are expelled within the petroleum window. The six petroleum systems we have identified and mapped are: a) a southern system involving the Kuna-Lisburne source rock unit that was active during the Late Jurassic and Early Cretaceous; b) two western systems involving source rock in the Kingak-Blankenship, and GRZ-lower Torok source rock units that were active during the Albian; and c) three eastern systems involving the Shublik-Otuk, Hue Shale and Canning source rock units that were active during the Cenozoic. The GRZ-lower Torok in the west is correlative with the Hue Shale to the east. Four overburden rock packages controlled the time of expulsion and gross geometry of migration paths: a) a southern package of Early Cretaceous and older rocks structurally-thickened by early Brooks Range thrusting; b) a western package of Early Cretaceous rocks that filled the western part of the foreland basin; c) an eastern package of Late Cretaceous and Paleogene rocks that filled the eastern part of the foreland basin; and d) an offshore deltaic package of Neogene rocks deposited by the Colville, Canning, and Mackenzie rivers. This petroleum system poster is part of a series of Northern Alaska posters on modeling. The poster in this session by Saltus and Bird present gridded maps for the greater Northern Alaskan onshore and offshore that are used in the 3D modeling poster by Lampe and others. Posters on source rock units are by Keller and Bird as well as

  2. Bowhead whale behavior in relation to seismic exploration, Alaskan Beaufort Sea, Autumn 1981. Study report (Final)

    SciTech Connect

    Fraker, M.A.; Ljungblad, D.K.; Richardson, W.J.; Van Schoik, D.R.

    1985-10-01

    Behavior of bowhead whales (Balsena mysticetus) in the eastern part of the Alaskan Beaufort Sea or near the Alaska/Yukon border was observed from a circling turbine-powered Goose aircraft on 10 dates from 12 September to 5 October 1981. On three of these dates, the whales were exposed t, noise impulses from seismic vessels 13 km or more away. Some behavioral data were acquired. In both the presence and the absence of seismic impulses, most bowheads appeared to be feeding in the water column, although slow travel and active socializing were sometimes detected. Sonobuoys detected bowhead calls both in the presence and the absence of seismic impulses. There was no clear evidence of unusual behavior in the presence of seismic impulses.

  3. Four Years of CARVE-FTS Observations of CO2, CH4, and CO in the Alaskan Arctic: Status Quo and Comparison with Satellite Measurements

    NASA Astrophysics Data System (ADS)

    Kurosu, T. P.; Miller, C. E.; Dinardo, S. J.

    2015-12-01

    The end of 2015 marks the conclusion of the Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE), a four-year aircraft-based Earth Venture 1 mission to study the carbon balance of the Alaskan Arctic ecosystem, with a particular focus on carbon release from melting permafrost. Operating from its base in Fairbanks, AK, the CARVE aircraft covers a range of principle flight paths in the Alaskan interior, the Yukon River valley, and the northern Alaska coast around Barrow and Dead Horse. Flight paths are chosen to maximize ecosystem variability and cover burn-recovery/regrowth sequences. CARVE observations cover the Arctic Spring/Summer/Fall seasons, with multiple flights per season and principle flight path. Science operations started in 05/2012 and will conclude in 11/2015. The CARVE suite of instruments includes flask measurements, in situ gas analyzers for CO2, CH4 and CO observations, and a three-band polarizing Fourier Transform Spectrometer (FTS) for column measurements of CO2, CH4, CO, their interfering species (e.g., H2O), and O2. The FTS covers the spectral regions of 4,200-4,900 cm-1 (CH4, CO), 5,800-6,400 cm-1 (CO2), and 12,900-13,200 cm-1 (O2), with a spectral resolution of 0.2 cm-1. Aircraft-based FTS science observations in Alaska have been performed since 23-05-2012. First-version data products from all CARVE instruments derived from observations during the 2012 campaign were publicly released earlier in 2013. The FTS has performed well during flight conditions. A recent overhaul of the retrieval algorithm has led to improvements in FTS data quality. We present results from FTS column observations of CO2, CH4, and CO, obtained over the entire CARVE observation record from 2012 to 2015, including comparisons of CARVE FTS measurements with satellite observations of GOSAT CO2 and CH4 retrieved by NIES, GOSAT CO2 from JPL/ACOS, MOPITT CO, and CO2 from OCO-2. The comparisons emphasize coincident CARVE/OCO-2 observations over Alaska during the 2015

  4. Observations of geese foraging for clam shells during spring on the Yukon-Kuskokwim Delta, Alaska

    USGS Publications Warehouse

    Flint, P.L.; Fowler, A.C.; Bottitta, G.E.; Schamber, J.

    1998-01-01

    We studied the behavior of geese on exposed river ice during spring on the Yukon-Kuskokwim Delta. The predominant behavior while on the ice for both sexes was foraging; however, females foraged more than males. Visual inspection of the ice revealed no potential plant or animal food items. However, numerous small (<20 man) clam shells (Macoma balthica) and pieces of shell were noted. It appeared that geese were foraging on empty clam shells. This potential source of calcium was available to breeding geese just prior to egg formation and geese likely stored this calcium in the form of medullary bone for use during egg formation.

  5. Evolution of eclogite facies metamorphism in the St. Cyr klippe, Yukon-Tanana terrane, Yukon, Canada

    NASA Astrophysics Data System (ADS)

    Petrie, Meredith Blair

    The St. Cyr klippe hosts well preserved to variably retrogressed eclogites found as sub-meter to hundreds of meter scale lenses within quartzofeldspathic schists in the Yukon-Tanana terrane, Canadian Cordillera. The St. Cyr area consists of structurally imbricated, polydeformed, and polymetamorphosed units of continental arc and oceanic crust. The eclogite-bearing quartzofeldspathic schists form a 30 by 6 kilometer thick, northwest-striking, coherent package. The schists consist of metasediments and felsic intrusives that are intercalated on the tens of meter scale. The presence of phengite and Permian age zircon crystallized under eclogite facies metamorphic conditions indicates that the eclogite was metamorphosed in situ with its quartzofeldspathic host. I investigated the metamorphic evolution of the eclogite-facies rocks in the St. Cyr klippe using isochemical phase equilibrium thermodynamic (pseudosection) modeling. I constructed P-T pseudosections in the system Na2O-K2O-CaO-FeO-O2-MnO-MgO-Al2O 3-SiO2-TiO2-H2O for the bulk-rock composition of an eclogite and a host metatonalite. In combination with petrology and mineral compositions, St. Cyr eclogites followed a five-stage clockwise P-T path. Peak pressure conditions for the eclogites and metatonalites reached up to 3.2 GPa, well within the coesite stability field, indicating the eclogites reached ultrahigh-pressure conditions. Decompression during exhumation occurred with a corresponding temperature increase. SHRIMP-RG zircon dating shows that the protolith of the eclogites formed within the Yukon-Tanana terrane during early, continental arc activity, between 364 and 380 Ma, while the metatonalite protolith formed at approximately 334 Ma, during the Little Salmon Cycle of the Klinkit phase of Yukon-Tanana arc activity. Both the eclogites and the metatonalites were then subducted to mantle depths and metamorphosed to ultrahigh-pressure conditions during the late Permian, between 266 and 271 Ma. The results of

  6. Alaskan thermokarst terrain and possible Martian analog

    NASA Technical Reports Server (NTRS)

    Gatto, L. W.; Anderson, D. M.

    1975-01-01

    A first-order analog to Martian fretted terrain has been recognized on enhanced, ERTS-1 (Earth Resources Technology Satellite) imagery of Alaskan Arctic thermokarst terrain. The Alaskan analog displays flat-floored valleys and intervalley uplands characteristic of fretted terrain. The thermokarst terrain has formed in a manner similar to one of the processes postulated for the development of the Martian fretted terrain.

  7. Structural and kinematic evolution of the Yukon-Tanana upland tectonites, east-central Alaska: A record of late Paleozoic to Mesozoic crustal assembly

    USGS Publications Warehouse

    Hansen, V.L.; Dusel-Bacon, C.

    1998-01-01

    The Yukon-Tanana terrane, the largest tectonostratigraphic terrane in the northern North American Cordillera, is polygenetic and not a single terrane. Lineated and foliated (L-S) tectonites, which characterize the Yukon-Tanana terrane, record multiple deformations and formed at different times. We document the polyphase history recorded by L-S tectonites within the Yukon-Tanana upland, east-central Alaska. These upland tectonites compose a heterogeneous assemblage of deformed igneous and metamorphic rocks that form the Alaskan part of what has been called the Yukon-Tanana composite terrane. We build on previous kinematic data and establish the three-dimensional architecture of the upland tectonites through kinematic and structural analysis of more than 250 oriented samples, including quartz c-axis fabric analysis of 39 samples. Through this study we distinguish allochthonous tectonites from parautochthonous tectonites within the Yukon-Tanana upland. The upland tectonites define a regionally coherent stacking order: from bottom to top, they are lower plate North American parautochthonous attenuated continental margin; continentally derived marginal-basin strata; and upper plate ocean-basin and island-arc rocks, including some continental basement rocks. We delineate three major deformation events in time, space, and structural level across the upland from the United States-Canada border to Fairbanks, Alaska: (1) pre-Early Jurassic (>212 Ma) northeast-directed, apparent margin-normal contraction that affected oceanic rocks; (2) late Early to early Middle Jurassic (>188-185 Ma) northwest-directed, apparent margin-parallel contraction and imbrication that resulted in juxtaposition of the allochthonous tectonites with parautochthonous continental rocks; and (3) Early Cretaceous (135-110 Ma) southeast-directed crustal extension that resulted in exposure of the structurally deepest, parautochthonous continental rocks. The oldest event represents deformation within a west

  8. Arctic nesting geese: alaskan populations

    USGS Publications Warehouse

    Hupp, Jerry W.; Stehn, Robert A.; Ely, Craig R.; Derksen, Dirk V.

    1995-01-01

    While data for some areas are lacking, populations of greater white-fronted geese (Anser albifrons frontalis) and medium-sized Canada geese (Branta canadensis) in interior and northern Alaska appear stable or have increased (King and Derksen 1986). Although only a small number of lesser snow geese (Chen caerulescens caerulescens) nest in Alaska, substantial populations occur in Canada and Russia. Populations of Pacific black brant (B. bernicla nigricans), emperor geese (C. canagica), greater white-fronted geese, and cackling Canada geese (B.c. minima) on the Yukon-Kuskokwim Delta (YKD) of western Alaska have declined from their historical numbers and are the focus of special management efforts (USFWS 1989). In addition, populations of tule white-fronted geese (A.a. gambeli), Aleutian Canada geese (B.c. leucopareia), Vancouver Canada Geese (B.c. fulva), and dusky Canada geese (B.c. occidentalis) are of special concern because of their limited geographic distributions and small numbers.

  9. Full-glacial paleosols in perennially frozen loess sequences, Klondike goldfields, Yukon Territory, Canada

    NASA Astrophysics Data System (ADS)

    Sanborn, Paul T.; Smith, C. A. Scott; Froese, Duane G.; Zazula, Grant D.; Westgate, John A.

    2006-07-01

    Perennially frozen loess deposits in the Klondike goldfields include paleosols formed in full-glacial environments, correlated by Alaskan distal tephra with Marine Isotope Stages (MIS) 2 and 4. Patterns of organic and inorganic carbon and clay distribution, microstructures, and profile morphologies indicate that soil formation occurred in a base-rich environment in which organic matter accreted predominantly as root detritus. At sites approximately 20 km apart, the expression of cryoturbation and ice wedge development decreases in strength upward in loess-paleosol sequences correlated with MIS 4, suggesting increasing aridity. Configurations of cryoturbation features and ice-wedge thaw unconformities, the presence of numerous ground squirrel burrows, and an absence of peat accumulation suggest that these substrates were predominantly well-drained, with active layers of equal or greater thickness than in modern soils on similar sites in the west-central Yukon. Some characteristics of these paleosols are similar to those of modern steppe and tundra soils, consistent with plant macrofossil evidence for local ecological diversity during full-glacial conditions in eastern Beringia.

  10. Arctic River Mobility: A Baseline Assessment

    NASA Astrophysics Data System (ADS)

    Rowland, J. C.; Wilson, C. J.; Brumby, S. P.; Pope, P. A.

    2009-12-01

    In many arctic river systems, permafrost and the presence of frozen floodplain materials provides a significant source of bank cohesion. Due to this cohesion, permafrost may play an important control of arctic river mobility and meandering dynamics. Whether changes in the rates of permafrost thawing has had or will have as significant a geomorphic impact on arctic river meandering as has already been observed for arctic coastline retreat, lake size and distribution, and hillslope stability is at present an unanswered question. The potential impact of climate driven changes in arctic river meandering has important implications for river planform morphology, floodplain dynamics, river ecology, and the export of carbon and nutrients to coastal oceans. We present results of remote sensing analysis of river mobility for the Yukon River in Alaska and sections of the Siberian Rivers including the Lena, the Kolyma and the Indigirka Rivers. Comparisons of river location at successive intervals in time were conducted using Landsat imagery archives and higher resolution aerial photographs and satellite imagery. Extraction of river channel locations was accomplished using the GeniePro automated feature extraction software. Over the period of Landsat coverage (mid-1980s to present) arctic rivers show limited to no movement at the resolution of the Landsat data (30 m per pixel). On the Yukon Flats regions of the Yukon River, the most mobile sections of the river have migration rates comparable to reach-average values reported for temperate rivers; given that large portions of the Yukon display no detectable movement, reach-averaged values are far less than observed in temperate systems. Field inspection of areas of high erosion along the Yukon River indicate that erosional processes associated with the thermal degradation of permafrost play a dominant role in many of these areas. Thermal niching and large scale bank collapse due to undercutting play a large role in bank erosion

  11. Tephrochronolgical Studies of Late Neogene Sediments in Interior Alaska and the Yukon Territory

    NASA Astrophysics Data System (ADS)

    Westgate, J. A.; Preece, S. J.; Froese, D. G.; Schweger, C. E.

    2004-12-01

    Our tephra studies of Late Neogene sediments in interior Alaska and Yukon are motivated by the need to provide a reliable time-stratigraphic framework for on-going palaeoenvironmental projects. Key sites are located in the Fairbanks, Chicken (Alaska) and Klondike (Yukon) goldfields, Old Crow Basin (Yukon), and the numerous bluffs along the Yukon River in Canada and eastern Alaska. Tephra beds are characterized by their field setting, petrography, geochemical composition of glass (majors and traces) and mineral phases (especially FeTi oxides), palaeomagnetic properties, and age (determined mostly by glass-fission-track methods). Two compositional groups are recognized. Type I beds have abundant bubble-wall glass shards and a small crop of crystals with pyroxene > hornblende. Its glass has a rhyolitic to dacitic composition with relatively high FeOt, Cs, Hf and low Al2O3, CaO, and Sr. REE profiles have a well-developed Eu anomaly with La/Yb < 13. Volcanics with this chemical signature are common throughout the Aleutian Alaska Peninsula arc (AAPA), which is, therefore, the presumed source of the type I distal beds. In contrast, type II beds have more abundant crystals (hornblende > > pyroxene) and the rhyolitic glass is mainly in the form of highly inflated pumice with high Al2O3, CaO, and Sr. REE profiles are steep with low heavy REE content along with a very weakly developed Eu anomaly, if present. The type II beds are unusual and have many of the characteristics of adakites, known to occur at Mount Drum and Mount Churchill in the Wrangell volcanic field (WVF), and at Hayes volcano at the northeastern end of the Alaska Peninsula arc. It is likely, therefore, that the source vents for the type II beds in interior Alaska and Yukon are located in or near the WVF. Twenty-five distinctive tephra beds have been recognized in the Gold Hill Loess at Fairbanks and a comparable number have been discovered in the Klondike goldfields, although few beds are common to both

  12. Studies of the Northern Alaskan Coastal System: Ongoing project work and synthesis activities

    NASA Astrophysics Data System (ADS)

    Douglas, T. A.; Sturm, M.; Ashjian, C. J.; Jorgensen, T.; Oechel, W. C.; Ping, C.; Rhew, R. C.; Stieglitz, M.

    2006-12-01

    Six ongoing projects focus on a better understanding of processes occurring along the Arctic Alaskan Coast. These projects, grouped as "Studies of the Northern Alaskan Coastal System", or SNACS, combine field, laboratory, modeling and human dimensions research. They include: 1) an investigation of climate variability, ocean processes, sea ice, bowhead whales, and Inupiat subsistence whaling, 2) research on the impact of variability within the ocean and atmosphere on terrestrial fluxes of carbon dioxide, dissolved organic matter and energy, 3) an inventory and description of soil organic carbon fluxes and ground ice in the coastal environment, 4) a determination of whether arctic coastal terrestrial ecosystems are significant sources or sinks of atmospheric methyl halides, chloroform and methane, 5) development of generalized discharge- constituent relationships for arctic basins, and 6) an investigation of the processes controlling mercury deposition to the coastal system. Three broad themes unite the projects: 1) nutrient fluxes from rivers and shoreline erosion in the Arctic coastal zone, 2) impacts of cryospheric changes on the Alaskan Arctic Coast, and 3) potential rapid regime shifts controlled by atmospheric and meteorological processes that could affect the Alaskan Arctic Coast. Warming of the Arctic, particularly its impact on sea ice and nutrient transport in arctic rivers is already affecting fundamental coastal system processes. The six SNACS projects are helping to understand how these impacts will evolve and what their ramifications will be both within and outside of the Arctic.

  13. Teaching in the Yukon: Exploring Teachers' Efficacy Beliefs, Stress, and Job Satisfaction in a Remote Setting

    ERIC Educational Resources Information Center

    Klassen, Robert M.; Foster, Rosemary Y.; Rajani, Sukaina; Bowman, Carley

    2009-01-01

    This article presents a mixed methods examination of teachers' job beliefs in the Yukon Territory in northern Canada. In Study 1 we used questionnaires to examine job beliefs for 221 teachers from the Yukon and western Canada. Teachers' self- and collective efficacy and workload stress were lower for Yukon teachers, but levels of overall stress…

  14. River Ice and Flood Detection Products Derived from Suomi NPP VIIRS Satellite Data to Support Hydrologic Forecast Operations in Alaska

    NASA Astrophysics Data System (ADS)

    van Breukelen, C. M.; Plumb, E. W.; Li, S.; Holloway, E.; Stevens, E.

    2015-12-01

    A lack of river ice data during spring break-up in Alaska creates many forecast challenges for National Weather Service (NWS) forecasters. Limited and infrequent ice conditions and flood observations are provided by river observers, community officials, and pilots. Although these observations are invaluable, there are extensive spatial and temporal data gaps across Alaska during spring break-up. The Suomi National Polar-orbiting Partnership (S-NPP) Visible Infrared Imaging Radiometer Suite (VIIRS) satellite imagery has proved to be an extremely beneficial situational awareness and decision support tool for NWS forecast operations. In particular, the VIIRS satellite imagery became highly effective in identifying extensive flooding of many Alaskan rivers due to ice jams during the 2013 spring breakup season. A devastating ice jam flood in the Yukon River community of Galena prompted the development of river ice and flood detection products derived from the VIIRS satellite imagery with the support of the Joint Polar Satellite System/Proving Ground and Risk Reduction (JPSS/PGRR) Program. The two new products from S-NPP/VIIRS imagery provided critical decision making information to NWS forecasters responsible for issuing flood warnings for the region. Since 2013, the NWS continues to evaluate the use of these products in an operational forecast setting, and has expanded the evaluation period to include summertime flooding. There are limitations of these products due to cloud cover, sun zenith angles, product validation, and other issues unique to Alaska. The NWS will continue to provide feedback to the JPSS/PGRR Program in order to further refine and improve the algorithms used to create the river ice and flood detection products. This presentation will demonstrate how these products have been integrated into the NWS forecast process for several types of flood events in Alaska.

  15. Cardiovascular Deaths among Alaskan Natives, 1980-86.

    ERIC Educational Resources Information Center

    Middaugh, John P.

    1990-01-01

    Analyzes death certificate data to discover the number of deaths of Alaskan natives caused by cardiovascular disease. Rates from cardiovascular diseases and atherosclerosis from 1980-86 among Alaskan natives were lower than rates among other Alaskans, while death rates from other causes were higher. Discusses the possible impact of diet. (JS)

  16. 75 FR 11905 - Yukon Flats National Wildlife Refuge, Fairbanks, AK

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-12

    ... or interests therein, from other willing sellers in other national wildlife refuges in Alaska, or to... Fish and Wildlife Service Yukon Flats National Wildlife Refuge, Fairbanks, AK AGENCY: U.S. Fish and... Wildlife Refuge final environmental impact statement. SUMMARY: We, the U.S. Fish and Wildlife...

  17. 75 FR 29582 - Yukon Flats National Wildlife Refuge, Fairbanks, AK

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-26

    ... proposed land exchange could magnify projected changes to Refuge resources from climate change. Fourth... proposed land exchange in the Refuge was published in the Federal Register on October 19, 2005 (70 FR 60845... final environmental impact statement (EIS) for a Proposed Land Exchange in the Yukon Flats...

  18. Degradation and Local Survival of Permafrost Through the Last Interglaciation in Interior Alaska and Yukon Territory

    NASA Astrophysics Data System (ADS)

    Reyes, A. V.; Froese, D. G.; Jensen, B. J.

    2006-12-01

    Permafrost in northern North America is warming, and recent modeling efforts have predicted the widespread disappearance of permafrost through much of the northern hemisphere over the next century. However, little is known of the impacts of past sustained warm intervals on permafrost dynamics, antiquity, and distribution due to difficulties in establishing reliable chronologies. Permafrost thus remains the last element of the Arctic cryosphere for which there is poor understanding of its adaptability to past warmer-than-present climate. Here we present observations from three sites in the region of interior Alaska and Yukon Territory that remained ice-free during Plio-Pleistocene glaciations, which collectively demonstrate the variable nature of the response of permafrost to warming during the last interglaciation. Chronology for all sites is based on identification of Old Crow tephra (OCt; 140±10 ka) by glass major element composition. Throughout the study region, OCt is consistently associated with organic-rich sediments that represent the last interglaciation on the basis of pollen, insect, and macrofossil assemblages. At the Palisades site on the Yukon River, 250 km west of Fairbanks, OCt is 1.5-3.5 m below thick (>1m) organic-rich silts and peats that are locally rich in beaver-chewed wood and large wood stumps, some of which are in growth position. In contrast, placer mining at Thistle Creek in central Yukon Territory exposes a dramatic thaw unconformity that is presumably related to local, but incomplete, permafrost degradation during the last interglaciation. In upslope positions at Thistle Creek, OCt is incorporated into a steeply dipping, 30 cm thick, organic-rich silt horizon that truncates at least one intact, relict ice wedge. The steeply dipping organic- rich horizon grades downslope into organic-rich silt with dense accumulations of wood fragments, including tree stems up to 2 m long. Evidence for similar permafrost degradation during the last

  19. Helping Kids Succeed--Alaskan Style.

    ERIC Educational Resources Information Center

    Association of Alaska School Boards, Juneau.

    The purpose of this book is to serve as a tool for individuals helping to make Alaskan communities places where youth can grow up to be strong, capable, and caring. The book is built around the Search Institute's Youth Developmental Assets Framework, which is comprised of the key building blocks in youth development. The book notes 40 assets that…

  20. Inconsistency in precipitation measurements across the Alaska-Yukon border

    NASA Astrophysics Data System (ADS)

    Scaff, L.; Yang, D.; Li, Y.; Mekis, E.

    2015-12-01

    This study quantifies the inconsistency in gauge precipitation observations across the border of Alaska and Yukon. It analyses the precipitation measurements by the national standard gauges (National Weather Service (NWS) 8 in. gauge and Nipher gauge) and the bias-corrected data to account for wind effect on the gauge catch, wetting loss and trace events. The bias corrections show a significant amount of errors in the gauge records due to the windy and cold environment in the northern areas of Alaska and Yukon. Monthly corrections increase solid precipitation by 136 % in January and 20 % for July at the Barter Island in Alaska, and about 31 % for January and 4 % for July at the Yukon stations. Regression analyses of the monthly precipitation data show a stronger correlation for the warm months (mainly rainfall) than for cold month (mainly snowfall) between the station pairs, and small changes in the precipitation relationship due to the bias corrections. Double mass curves also indicate changes in the cumulative precipitation over the study periods. This change leads to a smaller and inverted precipitation gradient across the border, representing a significant modification in the precipitation pattern over the northern region. Overall, this study discovers significant inconsistency in the precipitation measurements across the USA-Canada border. This discontinuity is greater for snowfall than for rainfall, as gauge snowfall observations have large errors in windy and cold conditions. This result will certainly impact regional, particularly cross-border, climate and hydrology investigations.

  1. Offshore oil in the Alaskan Arctic

    NASA Technical Reports Server (NTRS)

    Weeks, W. F.; Weller, G.

    1984-01-01

    Oil and gas deposits in the Alaskan Arctic are estimated to contain up to 40 percent of the remaining undiscovered crude oil and oil-equivalent natural gas within U.S. jurisdiction. Most (65 to 70 percent) of these estimated reserves are believed to occuur offshore beneath the shallow, ice-covered seas of the Alaskan continental shelf. Offshore recovery operations for such areas are far from routine, with the primary problems associated with the presence of ice. Some problems that must be resolved if efficient, cost-effective, environmentally safe, year-round offshore production is to be achieved include the accurate estimation of ice forces on offshore structures, the proper placement of pipelines beneath ice-produced gouges in the sea floor, and the cleanup of oil spills in pack ice areas.

  2. Evidence for permafrost thaw and transport from an Alaskan North Slope watershed

    NASA Astrophysics Data System (ADS)

    Schreiner, Kathryn M.; Bianchi, Thomas S.; Rosenheim, Brad E.

    2014-05-01

    Burial of organic carbon (OC) in marine sediments is one of the most important linkages between the short-term biologic carbon cycle and the long-term geologic carbon cycle. Yet much is still unknown about the fate of terrigenous OC in marine coastal margins. Here the delivery of particulate OC (POC) to the Colville River deltaic region in the Alaskan Beaufort Sea by particulates of varying densities is studied through the use of ramped temperature pyrolysis and radiocarbon analyses. The Colville River is the largest river in North America whose watershed is underlain completely by high Arctic permafrost tundra. A variety of sources of POC are considered, including terrestrial soils, Pleistocene-aged yedoma-like sediments, coastal peat erosion, and marine POC. We provide the first evidence that riverine POC from the Colville River contains old (Pleistocene-sourced) OC, suggesting ongoing thaw and mobilization of yedoma-like permafrost OC from this northern Alaskan watershed. Additionally, much of this OC appears to be fairly labile and therefore could be readily oxidized and returned to the atmosphere.

  3. Influence of permafrost distribution on groundwater flow in the context of climate-driven permafrost thaw: example from Yukon Flats Basin, Alaska, United States

    USGS Publications Warehouse

    Walvoord, Michelle A.; Voss, Clifford I.; Wellman, Tristan P.

    2012-01-01

    Understanding the role of permafrost in controlling groundwater flow paths and fluxes is central in studies aimed at assessing potential climate change impacts on vegetation, species habitat, biogeochemical cycling, and biodiversity. Recent field studies in interior Alaska show evidence of hydrologic changes hypothesized to result from permafrost degradation. This study assesses the hydrologic control exerted by permafrost, elucidates modes of regional groundwater flow for various spatial permafrost patterns, and evaluates potential hydrologic consequences of permafrost degradation. The Yukon Flats Basin (YFB), a large (118,340 km2) subbasin within the Yukon River Basin, provides the basis for this investigation. Model simulations that represent an assumed permafrost thaw sequence reveal the following trends with decreasing permafrost coverage: (1) increased groundwater discharge to rivers, consistent with historical trends in base flow observations in the Yukon River Basin, (2) potential for increased overall groundwater flux, (3) increased spatial extent of groundwater discharge in lowlands, and (4) decreased proportion of suprapermafrost (shallow) groundwater contribution to total base flow. These trends directly affect the chemical composition and residence time of riverine exports, the state of groundwater-influenced lakes and wetlands, seasonal river-ice thickness, and stream temperatures. Presently, the YFB is coarsely mapped as spanning the continuous-discontinuous permafrost transition that model analysis shows to be a critical threshold; thus, the YFB may be on the verge of major hydrologic change should the current permafrost extent decrease. This possibility underscores the need for improved characterization of permafrost and other hydrogeologic information in the region via geophysical techniques, remote sensing, and ground-based observations.

  4. Index of streamflow and water quality records to September 30, 1978, Yukon Basin, Alaska

    USGS Publications Warehouse

    Still, Patsy J.

    1980-01-01

    This report, which is one of a series of reports for Alaska, lists stations in Yukon Basin, Alaska, at which streamflow and water quality data have been collected by the U.S. Geological Survey. Included are a hydrologic subregion map of Yukon Basin, Alaska, and a table listing the types of data collected and periods of record. (USGS)

  5. 45 CFR 2532.20 - Special Demonstration Project for the Yukon-Kuskokwim Delta of Alaska.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...-Kuskokwim Delta of Alaska. 2532.20 Section 2532.20 Public Welfare Regulations Relating to Public Welfare... § 2532.20 Special Demonstration Project for the Yukon-Kuskokwim Delta of Alaska. (a) Special Demonstration Project for the Yukon-Kuskokwim Delta of Alaska. The President may award grants to, and enter...

  6. 45 CFR 2532.20 - Special Demonstration Project for the Yukon-Kuskokwim Delta of Alaska.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...-Kuskokwim Delta of Alaska. 2532.20 Section 2532.20 Public Welfare Regulations Relating to Public Welfare... § 2532.20 Special Demonstration Project for the Yukon-Kuskokwim Delta of Alaska. (a) Special Demonstration Project for the Yukon-Kuskokwim Delta of Alaska. The President may award grants to, and enter...

  7. 45 CFR 2532.20 - Special Demonstration Project for the Yukon-Kuskokwim Delta of Alaska.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...-Kuskokwim Delta of Alaska. 2532.20 Section 2532.20 Public Welfare Regulations Relating to Public Welfare... § 2532.20 Special Demonstration Project for the Yukon-Kuskokwim Delta of Alaska. (a) Special Demonstration Project for the Yukon-Kuskokwim Delta of Alaska. The President may award grants to, and enter...

  8. 45 CFR 2532.20 - Special Demonstration Project for the Yukon-Kuskokwim Delta of Alaska.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...-Kuskokwim Delta of Alaska. 2532.20 Section 2532.20 Public Welfare Regulations Relating to Public Welfare... § 2532.20 Special Demonstration Project for the Yukon-Kuskokwim Delta of Alaska. (a) Special Demonstration Project for the Yukon-Kuskokwim Delta of Alaska. The President may award grants to, and enter...

  9. 45 CFR 2532.20 - Special Demonstration Project for the Yukon-Kuskokwim Delta of Alaska.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...-Kuskokwim Delta of Alaska. 2532.20 Section 2532.20 Public Welfare Regulations Relating to Public Welfare... § 2532.20 Special Demonstration Project for the Yukon-Kuskokwim Delta of Alaska. (a) Special Demonstration Project for the Yukon-Kuskokwim Delta of Alaska. The President may award grants to, and enter...

  10. The Healthy Eating Handbook for Yukon First Nations. Occasional Publication No. 39.

    ERIC Educational Resources Information Center

    Nardelli, Vanessa M.; Wein, Eleanor E.

    The purpose of this handbook is to develop positive attitudes and skills toward healthy eating and healthy lifestyles among Yukon First Nations people. The introduction describes traditional food sources of the Yukon and how Native peoples met their nutritional needs by eating a variety of wild animal, fish, and plant foods. However, current…

  11. Breeding of steller's eiders, polysticta stellen, on the yukon-kuskokwim delta, Alaska

    USGS Publications Warehouse

    Flint', P. L.; Herzog, M.P.

    1999-01-01

    Historically, an unknown number of Steller's Eiders nested along the outer coastal fringe of the Yukon-Kuskokwim Delta, Alaska, but no nests had been found since 1975. We located six nests from 1991-1998 and we conclude that Steller's Eiders are still a regular breeder at low densities on the Yukon-Kuskokwim Delta.

  12. Breeding of Steller's Eiders, Polysticta stelleri, on the Yukon-Kuskokwim Delta, Alaska

    USGS Publications Warehouse

    Flint, P.L.; Herzog, M.P.

    1999-01-01

    Historically, an unknown number of Steller's Elders nested along the outer coastal fringe of the Yukon-Kuskokwim Delta, Alaska, but no nests had been found since 1975. We located six nests from 1991-1998 and we conclude that Steller's Elders are still a regular breeder at low densities on the Yukon-Kuskokwim Delta.

  13. Population structure over a broad spatial scale driven by nonanthropogenic factors in a wide-ranging migratory mammal, Alaskan caribou.

    PubMed

    Mager, Karen H; Colson, Kevin E; Groves, Pam; Hundertmark, Kris J

    2014-12-01

    Wide-ranging mammals face significant conservation threats, and knowledge of the spatial scale of population structure and its drivers is needed to understand processes that maintain diversity in these species. We analysed DNA from 655 Alaskan caribou (Rangifer tarandus granti) from 20 herds that vary in population size, used 19 microsatellite loci to document genetic diversity and differentiation in Alaskan caribou, and examined the extent to which genetic differentiation was associated with hypothesized drivers of population subdivision including landscape features, population size and ecotype. We found that Alaskan caribou are subdivided into two hierarchically structured clusters: one group on the Alaska Peninsula containing discrete herds and one large group on the Mainland lacking differentiation between many herds. Population size, geographic distance, migratory ecotype and the Kvichak River at the nexus of the Alaska Peninsula were associated with genetic differentiation. Contrary to previous hypotheses, small Mainland herds were often differentiated genetically from large interconnected herds nearby, and genetic drift coupled with reduced gene flow may explain this pattern. Our results raise the possibility that behaviour helps to maintain genetic differentiation between some herds of different ecotypes. Alaskan caribou show remarkably high diversity and low differentiation over a broad geographic scale. These results increase information for the conservation of caribou and other migratory mammals threatened by population reductions and landscape barriers and may be broadly applicable to understanding the spatial scale and ecological drivers of population structure in widespread species. PMID:25403098

  14. Educational Provisions for the Alaskan Natives Since 1867.

    ERIC Educational Resources Information Center

    Hopkins, Thomas Robert

    The study compiles and records the history of the administration of education for Alaskan natives since the United States purchased the territory from Russia in 1876. Chapter 1, An Overview of the Development of the Alaskan Native, covers the development of missionary and government schools, the growth and development of Native education from 1906…

  15. EarthScope Transportable Array (TA) Plans for Deployment in Alaska and Yukon

    NASA Astrophysics Data System (ADS)

    Hafner, K.; Busby, R. W.; Woodward, R.; Frassetto, A.

    2012-12-01

    The USArray portion of the National Science Foundation (NSF)-funded EarthScope project has been rolling across the continental United States from west to east since its construction began in October 2003. The Transportable Array (TA) element of Earthscope / USArray is a large deployment of 400 high quality broadband seismographs that is operated by the Incorporated Research Institutions for Seismology (IRIS) Consortium. The TA will reach the last installation in the eastern US in September 2013, after installing and operating 1678 stations. Following this ten-year deployment across the contiguous 48 US states and southernmost Canada the EarthScope USArray is expected to move to Alaska in 2014, contingent on a renewal proposal for the period FY14-FY18. The plan is to cover Alaska and parts of the Yukon Territory with approximately 300 stations at an 85 km grid-like spacing. The TA station grid will include about 35 existing seismic stations in Alaska. The NSF is currently supporting preparatory work to develop station design and communication concepts appropriate for the variable Alaska conditions. The siting of stations has been a focus of planning to-date, particularly the coordination with existing Alaskan seismic and GPS stations as well as Canadian stations. There is considerable interest in at least some of the stations becoming permanent assets to the existing station operators. We are also working on developing potential collaborative efforts with NOAA and other federal agencies, as well as groups conducting permafrost studies in the Arctic. We describe the station design, including modifications for long-term power and telemetry in remote regions. We have been testing sensor emplacement techniques that can be used across Alaska, particularly in regions of tundra underlain by permafrost, that will yield low horizontal noise at long periods. Results from several test stations are presented and the technique to emplace sensors is discussed. Feedback and

  16. Paleoecology of Beringian ?packrat? middens from central Yukon Territory, Canada

    NASA Astrophysics Data System (ADS)

    Zazula, Grant D.; Froese, Duane G.; Westgate, John A.; La Farge, Catherine; Mathewes, Rolf W.

    2005-03-01

    Rodent middens from ice-rich loess deposits are important new paleoenvironmental archives for Eastern Beringia. Plant macrofossils recovered from three middens associated with Dawson tephra (ca. 24,000 14C yr B.P.) at two sites in Yukon Territory include diverse graminoids, forbs, and mosses. These data suggest substantial local scale floristic and habitat diversity in valley settings, including steppe-tundra on well-drained soils, moist streamside meadows, and hydric habitats. Fossil arctic ground squirrel burrows and nesting sites indicate that permafrost active layers were thicker during Pleistocene glacial periods than at present on north-facing slopes.

  17. Carbon cycle uncertainty in the Alaskan Arctic

    NASA Astrophysics Data System (ADS)

    Fisher, J. B.; Sikka, M.; Oechel, W. C.; Huntzinger, D. N.; Melton, J. R.; Koven, C. D.; Ahlström, A.; Arain, M. A.; Baker, I.; Chen, J. M.; Ciais, P.; Davidson, C.; Dietze, M.; El-Masri, B.; Hayes, D.; Huntingford, C.; Jain, A. K.; Levy, P. E.; Lomas, M. R.; Poulter, B.; Price, D.; Sahoo, A. K.; Schaefer, K.; Tian, H.; Tomelleri, E.; Verbeeck, H.; Viovy, N.; Wania, R.; Zeng, N.; Miller, C. E.

    2014-08-01

    Climate change is leading to a disproportionately large warming in the high northern latitudes, but the magnitude and sign of the future carbon balance of the Arctic are highly uncertain. Using 40 terrestrial biosphere models for the Alaskan Arctic from four recent model intercomparison projects - NACP (North American Carbon Program) site and regional syntheses, TRENDY (Trends in net land atmosphere carbon exchanges), and WETCHIMP (Wetland and Wetland CH4 Inter-comparison of Models Project) - we provide a baseline of terrestrial carbon cycle uncertainty, defined as the multi-model standard deviation (σ) for each quantity that follows. Mean annual absolute uncertainty was largest for soil carbon (14.0 ± 9.2 kg C m-2), then gross primary production (GPP) (0.22 ± 0.50 kg C m-2 yr-1), ecosystem respiration (Re) (0.23 ± 0.38 kg C m-2 yr-1), net primary production (NPP) (0.14 ± 0.33 kg C m-2 yr-1), autotrophic respiration (Ra) (0.09 ± 0.20 kg C m-2 yr-1), heterotrophic respiration (Rh) (0.14 ± 0.20 kg C m-2 yr-1), net ecosystem exchange (NEE) (-0.01 ± 0.19 kg C m-2 yr-1), and CH4 flux (2.52 ± 4.02 g CH4 m-2 yr-1). There were no consistent spatial patterns in the larger Alaskan Arctic and boreal regional carbon stocks and fluxes, with some models showing NEE for Alaska as a strong carbon sink, others as a strong carbon source, while still others as carbon neutral. Finally, AmeriFlux data are used at two sites in the Alaskan Arctic to evaluate the regional patterns; observed seasonal NEE was captured within multi-model uncertainty. This assessment of carbon cycle uncertainties may be used as a baseline for the improvement of experimental and modeling activities, as well as a reference for future trajectories in carbon cycling with climate change in the Alaskan Arctic and larger boreal region.

  18. Engaging Alaskan Students in Cryospheric Research

    NASA Astrophysics Data System (ADS)

    Yoshikawa, K.; Sparrow, E. B.; Kopplin, M.

    2011-12-01

    The Permafrost/Active Layer Monitoring Program is an ongoing project, which builds on work begun in 2005 to establish long-term permafrost and active layer monitoring sites adjacent to schools in Alaskan communities and in the circumpolar permafrost region. Currently, there are about 200 schools in Alaska involved in the project including also Denali National Park and Preserve. The project has both scientific and outreach components. The monitoring sites collect temperature data on permafrost, and the length and depth of the active layer (the layer above the permafrost that thaws during summer and freezes again during winter). To ensure scientific integrity, the scientist installed all of the monitoring instruments and selected the sites representative of the surrounding biome and thermal conditions. This is a unique collaboration opportunity in that 1) uses scientifically accurate instruments, 2) is scientist led and supervised including instrumentation set-up and data quality check, 3)has teacher/student organized observation network, 4) increased spatial scale of monitoring sites that covers all of the Alaskan communities. Most of the monitoring sites are located in remote communities, where the majority of residents depend on a subsistence lifestyle. Changes in climate, length of seasons, and permafrost conditions directly impact natural resources and subsistence activities. Changes in permafrost conditions also affect local ecosystems and hydrological regimes, and can influence the severity of natural disasters. In addition to extending our knowledge of the arctic environment, the program involves school-age students. Several students have been using the data for their projects and have been inspired to continue their studies. The data gathered from these stations are shared with other schools and made available to the public through our web site (http://www.uaf.edu/permafrost). Also communities have increasingly become interested in this project not only as

  19. ERTS imagery applied to Alaskan coastal problems. [surface water circulation

    NASA Technical Reports Server (NTRS)

    Wright, F. F.; Sharma, G. D.; Burbank, D. C.; Burns, J. J.

    1974-01-01

    Along the Alaska coast, surface water circulation is relatively easy to study with ERTS imagery. Highly turbid river water, sea ice, and fluvial ice have proven to be excellent tracers of the surface waters. Sea truth studies in the Gulf of Alaska, Cook Inlet, Bristol Bay, and the Bering Strait area have established the reliability of these tracers. ERTS imagery in the MSS 4 and 5 bands is particularly useful for observing lower concentrations of suspended sediment, while MSS 6 data is best for the most concentrated plumes. Ice features are most clearly seen on MSS 7 imagery; fracture patterns and the movement of specific floes can be used to map circulation in the winter when runoff is restricted, if appropriate allowance is made for wind influence. Current patterns interpreted from satellite data are only two-dimensional, but since most biological activity and pollution are concentrated near the surface, the information developed can be of direct utility. Details of Alaska inshore circulation of importance to coastal engineering, navigation, pollution studies, and fisheries development have been clarified with satellite data. ERTS has made possible the analysis of circulation in many parts of the Alaskan coast.

  20. U-Pb zircon and geochemical evidence for bimodal mid-Paleozoic magmatism and syngenetic base-metal mineralization in the Yukon-Tanana terrane, Alaska

    USGS Publications Warehouse

    Dusel-Bacon, C.; Wooden, J.L.; Hopkins, M.J.

    2004-01-01

    New SHRIMP (sensitive, high-resolution ion microprobe) U-Pb zircon ages and trace element geochemical data for mafic and felsic metaigneous rocks of the pericratonic Yukon-Tanana terrane in east-central Alaska help define the tectonic setting of mid-Paleozoic magmatism and syngenetic hydrothermal Zn-Pb-Ag mineralization along the ancient Pacific margin of North America. We compare data from similar greenschist-facies sequences of bimodal volcanic and subvolcanic rocks associated with carbonaceous and siliciclastic marine sedimentary rocks, in the Wood River area of the Alaska Range and the Salcha River area of the Yukon-Tanana Upland, and from amphibolite-facies augen gneiss and mafic gneiss (amphibolite) in the Goodpaster River area of the upland. Allowing for analytical uncertainties, igneous crystallization age ranges of 376-353 Ma, 378-346 Ma, and 374-358 Ma are indicated by 13 new SHRIMP U-Pb dates for the Wood River, Salcha River, and Goodpaster River areas, respectively. Bimodal magmatism is indicated by Late Devonian crystallization ages for both augen gneiss (371 ?? 3 and 362 ?? 4 Ma) and associated orthoamphibolite (369 ?? 3 Ma) in the upland and by stratigraphic interleaving of mafic and felsic rocks in the Alaska Range. Metabasites in all three study areas have elevated HFSE (high field strength element) and REE (rare earth element) contents indicative of generation in a within-plate (extensional) tectonic setting. Within-plate trace element signatures also are indicated for peralkaline metarhyolites that host the largest volcanogenic massive sulfide deposits of the Bonnifield district in the Wood River area and for metarhyolite tuff interlayered with the carbonaceous Nasina assemblage, which hosts sedimentary exhalative sulfide occurrences in the Salcha River area. Most of the other felsic metaigneous samples from the Alaska Range and the Yukon-Tanana Upland have geochemical signatures that are similar to those of both average upper continental crust

  1. New porcellioidean gastropods from early Devonian of Royal Creek area, Yukon Territory, Canada, with notes on their early phylogeny

    USGS Publications Warehouse

    Fryda, J.; Blodgett, R.B.; Lenz, A.C.; Manda, S.

    2008-01-01

    This paper presents a description of new gastropods belonging to the superfamily Porcellioidea (Vetigastropoda) from the richly diverse Lower Devonian gastropod fauna of the Road River Formation in the Royal Creek area, Yukon Territory. This fauna belongs to Western Canada Province of the Old World Realm. The Pragian species Porcellia (Porcellia) yukonensis n. sp. and Porcellia (Paraporcellia) sp. represent the oldest presently known members of subgenera Porcellia (Porcellia) and Porcellia (Paraporcellia). Their simple shell ornamentation fits well with an earlier described evolutionary trend in shell morphology of the Porcellinae. Late Pragian to early Emsian Perryconcha pulchra n. gen. and n. sp. is the first member of the Porcellioidea bearing a row of tremata on adult teleoconch whorls. The occurrence of this shell feature in the Porcellioidea is additional evidence that the evolution of the apertural slit was much more complicated than has been proposed in classical models of Paleozoic gastropod evolution. Copyright ?? 2008, The Paleontological Society.

  2. Sufentanil citrate immobilization of Alaskan moose calves.

    PubMed

    Kreeger, Terry J; Kellie, Kalin A

    2012-10-01

    Free-ranging Alaskan moose calves (Alces alces gigas) were immobilized with 0.12 mg/kg sufentanil (S; n=16), 0.12 mg/kg sufentanil plus 0.27 mg/kg xylazine (SX; n=11), or 0.007 mg/kg carfentanil plus 0.36 mg/kg xylazine (CX; n=13). Immobilants were antagonized with 1.2 mg/kg naltrexone (S) or 1.2 mg/kg naltrexone plus 2.4 mg/kg tolazoline (SX, CX). There were no differences in induction (P ≥ 0.29) or processing (P ≥ 0.44) times between groups. Moose given either S or SX had significantly shorter recovery times than moose given CX (P=0.001) and recovery times from S were shorter than from SX (P=0.02). Oxygen saturation values for all groups averaged 85 ± 8%, but were significantly higher (P=0.048) for CX (89 ± 7%) than for S (82 ± 8%). Based on these data, sufentanil at 0.1 mg/kg or sufentanil at 0.1 mg/kg plus xylazine at 0.25 mg/kg could provide effective remote immobilization for Alaskan moose calves and could be substituted for carfentanil or thiafentanil should the need arise. PMID:23060515

  3. The Current Tectonics of the Yukon and Adjacent Area

    NASA Astrophysics Data System (ADS)

    Hyndman, R. D.; Leonard, L. J.

    2014-12-01

    The current tectonics across the Yukon and adjacent areas of western Northwest Territories (NWT) and northern British Columbia appear to be driven primarily by the Yakutat Terrane collision, an "indenter" in the corner of the Gulf of Alaska. GPS data show 1-10 mm/yr northward and eastward, decreasing inland. The rates from earthquake statistics are similar although there are important discrepancies. The eastern Cordillera earthquake mechanisms are mainly thrust in the Mackenzie Mountains of southwestern NWT where the Cordillera upper crust is overthrusting the craton. To the north, the mechanisms are mainly strike-slip in the Richardson Mountains that appear to lie along the edge of the craton. The deformation appears to be limited to the hot and weak Cordillera with the strong craton providing an irregular eastern boundary. For example, there is an eastward bow in the craton edge and the deformation in the Mackenzie Mountains. On the Beaufort Sea margin in the region of the Mackenzie Delta there appears to be a type of "subduction zone" with the continent very slowly overthrusting the oceanic plate, a process that has continued since at least the Cretaceous. A northward moving continental margin block is bounded by left lateral faulting in the west (Canning Displacement Zone of eastern Alaska) and right lateral faulting in the east (Richardson Mountains in eastern Yukon). There is almost no seismicity on this thrust belt but as for some other subduction zones such as Cascadia there is the potential for very infrequent great earthquakes.

  4. Decline in a population of spectacled eiders nesting on the Yukon-Kuskokwim Delta, Alaska

    USGS Publications Warehouse

    Ely, Craig; Dau, Christian; Babcock, Christopher

    1994-01-01

    The number of spectacled eiders nesting on two study areas near the Kashunuk River, on the central Yukon-Kuskokwim (Y-K) Delta, Alaska, declined by over 75% in the last 20 years. Nesting densities have remained low, but have not significantly declined since 1985. There has been no decrease in the reproductive effort of individual females as indicated by average clutch sizes. There has been a significant decline in the proportion of nests located on islands on one of the two study areas. Nesting success declined significantly during the 1970's. Success was not monitored in recent years, but has likely been low, based on the poor nesting success and declining numbers of cackling Canada geese and black brant nesting on the area. Nest predation by arctic foxes severely limited the productivity of cackling Canada geese, and foxes were likely the major predators of eider nests. Persistent high predation rates may lead to local extirpation in highly philopatric species such as eiders.

  5. Preliminary study on total mercury in the common prepared subsistence foods of a rural Alaskan village.

    PubMed

    Rothschild, Roger F N; Duffy, Lawrence K

    2002-01-01

    Total mercury (THg), which includes neurotoxic methylmercury (MeHg), poses a health risk to subsistence food users in the circumpolar north. Low levels of THg, usually below 200 ng/g, have been reported in fish muscle from both returning salmon and freshwater species samples on the Kuskokwim River in southwest Alaska. Alaska subsistence users use fish all year long, with both salmon and freshwater species stored for winter usage. A recent study showed low mercury levels in the hair of villagers and suggested that in the last 25 years, MeHg exposure has remained the same or slightly decreased in the Bethel region of Alaska. Although several previous studies have measured THg in hair of Alaskan subsistence food users, few studies have looked at the THg levels in the prepared foods of rural Alaskans. Several types of subsistence foods from Napakiak, a small Yup'ik Eskimo village on the Kuskokwim River, were assessed for total mercury content. The THg levels were low, ranging from 1 ng/g to 443.8 ng/g. A trend for the dried fish to have higher concentrations than the unprocessed fish was observed. Plants, as well as raindeer and moose meats, are low in THg and not associated with dietary exposure. Our data for Napakiak show that THg levels are low enough that mercury does not pose a significant health risk; however, more detailed consumption data in western Alaska is needed. PMID:12650086

  6. Carbon cycle uncertainty in the Alaskan Arctic

    NASA Astrophysics Data System (ADS)

    Fisher, J. B.; Sikka, M.; Oechel, W. C.; Huntzinger, D. N.; Melton, J. R.; Koven, C. D.; Ahlström, A.; Arain, A. M.; Baker, I.; Chen, J. M.; Ciais, P.; Davidson, C.; Dietze, M.; El-Masri, B.; Hayes, D.; Huntingford, C.; Jain, A.; Levy, P. E.; Lomas, M. R.; Poulter, B.; Price, D.; Sahoo, A. K.; Schaefer, K.; Tian, H.; Tomelleri, E.; Verbeeck, H.; Viovy, N.; Wania, R.; Zeng, N.; Miller, C. E.

    2014-02-01

    Climate change is leading to a disproportionately large warming in the high northern latitudes, but the magnitude and sign of the future carbon balance of the Arctic are highly uncertain. Using 40 terrestrial biosphere models for Alaska, we provide a baseline of terrestrial carbon cycle structural and parametric uncertainty, defined as the multi-model standard deviation (σ) against the mean (x\\bar) for each quantity. Mean annual uncertainty (σ/x\\bar) was largest for net ecosystem exchange (NEE) (-0.01± 0.19 kg C m-2 yr-1), then net primary production (NPP) (0.14 ± 0.33 kg C m-2 yr-1), autotrophic respiration (Ra) (0.09 ± 0.20 kg C m-2 yr-1), gross primary production (GPP) (0.22 ± 0.50 kg C m-2 yr-1), ecosystem respiration (Re) (0.23 ± 0.38 kg C m-2 yr-1), CH4 flux (2.52 ± 4.02 g CH4 m-2 yr-1), heterotrophic respiration (Rh) (0.14 ± 0.20 kg C m-2 yr-1), and soil carbon (14.0± 9.2 kg C m-2). The spatial patterns in regional carbon stocks and fluxes varied widely with some models showing NEE for Alaska as a strong carbon sink, others as a strong carbon source, while still others as carbon neutral. Additionally, a feedback (i.e., sensitivity) analysis was conducted of 20th century NEE to CO2 fertilization (β) and climate (γ), which showed that uncertainty in γ was 2x larger than that of β, with neither indicating that the Alaskan Arctic is shifting towards a certain net carbon sink or source. Finally, AmeriFlux data are used at two sites in the Alaskan Arctic to evaluate the regional patterns; observed seasonal NEE was captured within multi-model uncertainty. This assessment of carbon cycle uncertainties may be used as a baseline for the improvement of experimental and modeling activities, as well as a reference for future trajectories in carbon cycling with climate change in the Alaskan Arctic.

  7. Eastern Denali Fault Slip Rate and Paleoseismic History, Kluane Lake Area, Yukon Territory, Canada

    NASA Astrophysics Data System (ADS)

    Seitz, G. J.; Haeussler, P. J.; Crone, A. J.; Lipovsky, P.; Schwartz, D. P.

    2008-12-01

    In 2002, the central part of the dextral-slip Denali fault (DF) system generated a M 7.9 earthquake in central Alaska. This rupture included the section of the Denali fault with the highest measured late Pleistocene slip rate, of 12.1±1.7 mm/yr, and the Totschunda fault, with a slip rate of 6.0±1.2 mm/yr. Immediately east of the Denali-Totschunda fault juncture, the slip rate on the eastern Denali fault (EDF) decreases to 8.4±2.2 mm/yr. We present observations of Holocene fault activity on the Yukon part of the EDF (Shakwak segment), which is located about 280 km southeast of the Denali-Totschunda intersection in the vicinity of Kluane Lake. Aerial reconnaissance in 2007, from the Denali-Totschunda fault juncture to the Kluane Lake region revealed a nearly continuously identifiable fault trace, which is occasionally obscured where it is subparallel to glacial landforms. In addition to geomorphic features associated with strike-slip faults, such as shutter ridges and sag ponds, the fault is commonly expressed by a chain of elongate mounds, likely tectonic pushups, 20-70 m in length, 10-50 m wide, and locally up to 10 m high. These appear to have formed by shortening between en echelon left-stepping fault strands that developed in layered glacial sediments. At one location (61°18'30.12" N, 139°01'02.54"W) we measured on the ground a channel offset of 20-25 m. An aerial view showed that other channels in the vicinity, as well as the margins of two mounds, were offset by similar amounts. These channels likely developed after deglaciation 10-12 ka. Using this age and the offset yields a slip-rate range of 1.7-2.5 mm/yr, a minimum value but one that may be close to the actual rate. However, because of uncertainties in age relations between construction of the uplift mounds and channel incision the offset could be younger and we estimate an upper limit of about 5 mm/yr. Adjacent to and south of the Duke River, an approximately 2-km-long section of the fault is

  8. Development of Alaskan gas hydrate resources

    SciTech Connect

    Kamath, V.A.; Sharma, G.D.; Patil, S.L.

    1991-06-01

    The research undertaken in this project pertains to study of various techniques for production of natural gas from Alaskan gas hydrates such as, depressurization, injection of hot water, steam, brine, methanol and ethylene glycol solutions through experimental investigation of decomposition characteristics of hydrate cores. An experimental study has been conducted to measure the effective gas permeability changes as hydrates form in the sandpack and the results have been used to determine the reduction in the effective gas permeability of the sandpack as a function of hydrate saturation. A user friendly, interactive, menu-driven, numerical difference simulator has been developed to model the dissociation of natural gas hydrates in porous media with variable thermal properties. A numerical, finite element simulator has been developed to model the dissociation of hydrates during hot water injection process.

  9. River mobility in a permafrost dominated floodplain

    NASA Astrophysics Data System (ADS)

    Rowland, J.; Wilson, C.; Brumby, S.; Pope, P.

    2009-04-01

    Along arctic coastlines, recent studies have attributed dramatic increases in the rates of shoreline erosion to global climate change and permafrost degradation. While across much of the arctic, changes in the size and number of lakes have been interpreted as the result of permafrost degradation altering surface water dynamics. The potential influence of climate change and permafrost thawing on the mobility and form of arctic rivers, however, has been relatively unexplored to date. In rivers located within permafrost, some to potentially most, of the cohesive bank strength may be derived from frozen materials. It is likely that, as permafrost thaws, river bank erosion may increase, in turn influencing both migration rates and channel planform. Using automated feature extraction software (GeniePro), we quantified the of the mobility of a 200 km reach of the Yukon River through the Yukon Flats region located just north of Fairbanks, Alaska, USA. The Yukon Flats is an area of comprised of both continuous and discontinuous permafrost. Based on both changes in lake distributions and wintertime river base flows, it has been suggested that permafrost in this area has been experiencing recent thawing. In this reach, the Yukon River transitions from a 2 km wide braided channel to a multi-thread meandering channel where individual threads are approximately 1 km wide and the floodplain preserves prior meander cutoffs and oxbow lakes. Preliminary results from thirty years of LANDSAT imagery shows a surprising stability of channel location (at the image resolution of 30m/pixel) given the channel form. Within the braid-belt there is localized relocation of channel threads and mid-channel islands, though along much of the reach, the change in the location of channels banks is close to the resolution of the imagery. At the most active bends, bank migration rates range from 0.007 to 0.02 channel widths per year. These rates are comparable to system wide average rates observed on

  10. Two flysch belts having distinctly different provenance suggest no stratigraphic link between the Wrangellia composite terrane and the paleo-Alaskan margin

    USGS Publications Warehouse

    Hults, Chad P.; Wilson, Frederic H.; Donelick, Raymond A.; O'Sullivan, Paul B.

    2013-01-01

    The provenance of Jurassic to Cretaceous flysch along the northern boundary of the allochthonous Wrangellia composite terrane, exposed from the Lake Clark region of southwest Alaska to the Nutzotin Mountains in eastern Alaska, suggests that the flysch can be divided into two belts having different sources. On the north, the Kahiltna flysch and Kuskokwim Group overlie and were derived from the Farwell and Yukon-Tanana terranes, as well as smaller related terranes that were part of the paleo-Alaskan margin. Paleocurrent indicators for these two units suggest that they derived sediment from the north and west. Sandstones are predominantly lithic wacke that contain abundant quartz grains, lithic rock fragments, and detrital mica, which suggest that these rocks were derived from recycled orogen and arc sources. Conglomerates contain limestone clasts that have fossils matching terranes that made up the paleo-Alaskan margin. In contrast, flysch units on the south overlie and were derived from the Wrangellia composite terrane. Paleocurrent indicators for these units suggest that they derived sediment from the south. Sandstones are predominantly feldspathic wackes that contain abundant plagioclase grains and volcanic rock fragments, which suggest these rocks were derived from an arc. Clast compositions in conglomerate south of the boundary match rock types of the Wrangellia composite terrane. The distributions of detrital zircon ages also differentiate the flysch units. Flysch units on the north average 54% Mesozoic, 14% Paleozoic, and 32% Precambrian detrital zircons, reflecting derivation from the older Yukon-Tanana, Farewell, and other terranes that made up the paleo-Alaskan margin. In comparison, flysch units on the south average 94% Mesozoic, 1% Paleozoic, and 5% Precambrian zircons, which are consistent with derivation from the Mesozoic oceanic magmatic arc rocks in the Wrangellia composite terrane. In particular, the flysch units on the south contain a large

  11. Comparative metagenome analysis of an Alaskan glacier.

    PubMed

    Choudhari, Sulbha; Lohia, Ruchi; Grigoriev, Andrey

    2014-04-01

    The temperature in the Arctic region has been increasing in the recent past accompanied by melting of its glaciers. We took a snapshot of the current microbial inhabitation of an Alaskan glacier (which can be considered as one of the simplest possible ecosystems) by using metagenomic sequencing of 16S rRNA recovered from ice/snow samples. Somewhat contrary to our expectations and earlier estimates, a rich and diverse microbial population of more than 2,500 species was revealed including several species of Archaea that has been identified for the first time in the glaciers of the Northern hemisphere. The most prominent bacterial groups found were Proteobacteria, Bacteroidetes, and Firmicutes. Firmicutes were not reported in large numbers in a previously studied Alpine glacier but were dominant in an Antarctic subglacial lake. Representatives of Cyanobacteria, Actinobacteria and Planctomycetes were among the most numerous, likely reflecting the dependence of the ecosystem on the energy obtained through photosynthesis and close links with the microbial community of the soil. Principal component analysis (PCA) of nucleotide word frequency revealed distinct sequence clusters for different taxonomic groups in the Alaskan glacier community and separate clusters for the glacial communities from other regions of the world. Comparative analysis of the community composition and bacterial diversity present in the Byron glacier in Alaska with other environments showed larger overlap with an Arctic soil than with a high Arctic lake, indicating patterns of community exchange and suggesting that these bacteria may play an important role in soil development during glacial retreat. PMID:24712530

  12. Temporal and Spatial Patterns in Thermokarst Lake Area Change in Yukon Flats, Alaska: an Indication of Permafrost Degradation

    NASA Astrophysics Data System (ADS)

    Chen, M.; Rowland, J. C.; Wilson, C. J.; Altmann, G.; Brumby, S. P.

    2011-12-01

    The formation, expansion, and drainage of thermokarst lakes is determined by the lateral and vertical degradation of permafrost. Consequently, areal changes in thermokarst lakes can reflect changes in the spatial distribution and depth of permafrost. However, natural variability in lake areas confounds the long term trend and makes it difficult to detect permafrost degradation by simply comparing lake areas from different time periods. In this study, we used Landsat images of 16 time periods between 1984 and 2009 to extract lake area (closed basin lakes only) for a 422,382 ha study area within Yukon Flats, Alaska. A multiple linear regression model was built to quantify the long term change in lake area. In this model, we included LWB (local water balance, defined as difference between total precipitation and total potential evapotranspiration since the preceding October), MDT (mean daily temperature from May 1st to the date that Landsat image was acquired) and PRD (four time periods: 1984-1986, 1992, 1999-2002, and 2009). MDT was used to indicate the active layer depth. Both LWB and MDT were used to account for natural variability in lake area. The model explained 95% of the total variability in lake area, with 62%, 16% and 17% accounted for by LWB, MDT and PRD respectively. Using the total lake area (15898 ha) in 1984-1986 as a baseline, lake area increased by 12% in 1992, and decreased by 6% during 1999-2002 and 8% in 2009. Among the 1,667 lakes, 267 lakes showed an area decrease and 115 lakes showed an increase. The expanding lakes were distributed along the Yukon River and its main tributaries (Beaver creek and Birch creek), while the shrinking lakes were located farther away from rivers or on fluvial terraces. A potential reason for the spatial pattern of expanding and shrinking lakes is that, after permafrost thaws, lakes can become connected to the groundwater system. Lakes close to the rivers may be recharged by groundwater due to their lower position

  13. Alaska Is Our Home--Book 3: A Natural Science Handbook for Alaskan Students.

    ERIC Educational Resources Information Center

    Bury, John; Bury, Susan

    The third book in a series of natural science handbooks for Alaskan students focuses on Alaskan plantlife. The first chapter, on trees, gives general information about trees and explains how to identify and locate trees in the three main Alaskan tree families: pine, willow, and birch. The second chapter, on plants, describes 14 kinds of edible…

  14. American Indian Policy Review Commission Special Joint Task Force Report on Alaskan Native Issues.

    ERIC Educational Resources Information Center

    Congress of the U.S. Washington, DC. American Indian Policy Review Commission.

    Impact of the Alaskan Native Claims Settlement Act (ANCSA) on Alaskan Natives, particularly at village levels, is the focus of a joint task force report on Alaskan Native issues. Prepared for the American Indian Policy Review Commission, the report is the work of representatives from task forces on tribal government, federal, state, and tribal…

  15. 40 CFR 408.200 - Applicability; description of the Alaskan bottom fish processing subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Alaskan bottom fish processing subcategory. 408.200 Section 408.200 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Alaskan Bottom Fish Processing Subcategory § 408.200 Applicability; description of the Alaskan bottom fish processing subcategory. The provisions of this subpart are...

  16. 40 CFR 408.200 - Applicability; description of the Alaskan bottom fish processing subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Alaskan bottom fish processing subcategory. 408.200 Section 408.200 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Alaskan Bottom Fish Processing Subcategory § 408.200 Applicability; description of the Alaskan bottom fish processing subcategory. The provisions of this subpart are...

  17. 40 CFR 408.50 - Applicability; description of the remote Alaskan crab meat processing subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... remote Alaskan crab meat processing subcategory. 408.50 Section 408.50 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Remote Alaskan Crab Meat Processing Subcategory § 408.50 Applicability; description of the remote Alaskan crab meat processing subcategory. The provisions of this subpart...

  18. 40 CFR 408.50 - Applicability; description of the remote Alaskan crab meat processing subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... remote Alaskan crab meat processing subcategory. 408.50 Section 408.50 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Remote Alaskan Crab Meat Processing Subcategory § 408.50 Applicability; description of the remote Alaskan crab meat processing subcategory. The provisions of this subpart...

  19. 40 CFR 408.50 - Applicability; description of the remote Alaskan crab meat processing subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... remote Alaskan crab meat processing subcategory. 408.50 Section 408.50 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Remote Alaskan Crab Meat Processing Subcategory § 408.50 Applicability; description of the remote Alaskan crab meat processing subcategory. The provisions of this subpart...

  20. 40 CFR 408.50 - Applicability; description of the remote Alaskan crab meat processing subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... remote Alaskan crab meat processing subcategory. 408.50 Section 408.50 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Remote Alaskan Crab Meat Processing Subcategory § 408.50 Applicability; description of the remote Alaskan crab meat processing subcategory. The provisions of this subpart...

  1. 40 CFR 408.50 - Applicability; description of the remote Alaskan crab meat processing subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... remote Alaskan crab meat processing subcategory. 408.50 Section 408.50 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Remote Alaskan Crab Meat Processing Subcategory § 408.50 Applicability; description of the remote Alaskan crab meat processing subcategory. The provisions of this subpart...

  2. 40 CFR 408.170 - Applicability; description of the Alaskan mechanized salmon processing subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Alaskan mechanized salmon processing subcategory. 408.170 Section 408.170 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Alaskan Mechanized Salmon Processing Subcategory § 408.170 Applicability; description of the Alaskan mechanized salmon processing subcategory. The provisions of this subpart...

  3. 40 CFR 408.170 - Applicability; description of the Alaskan mechanized salmon processing subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Alaskan mechanized salmon processing subcategory. 408.170 Section 408.170 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Alaskan Mechanized Salmon Processing Subcategory § 408.170 Applicability; description of the Alaskan mechanized salmon processing subcategory. The provisions of this subpart...

  4. 40 CFR 408.170 - Applicability; description of the Alaskan mechanized salmon processing subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Alaskan mechanized salmon processing subcategory. 408.170 Section 408.170 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Alaskan Mechanized Salmon Processing Subcategory § 408.170 Applicability; description of the Alaskan mechanized salmon processing subcategory. The provisions of this subpart...

  5. 40 CFR 408.170 - Applicability; description of the Alaskan mechanized salmon processing subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Alaskan mechanized salmon processing subcategory. 408.170 Section 408.170 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Alaskan Mechanized Salmon Processing Subcategory § 408.170 Applicability; description of the Alaskan mechanized salmon processing subcategory. The provisions of this subpart...

  6. 40 CFR 408.170 - Applicability; description of the Alaskan mechanized salmon processing subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Alaskan mechanized salmon processing subcategory. 408.170 Section 408.170 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Alaskan Mechanized Salmon Processing Subcategory § 408.170 Applicability; description of the Alaskan mechanized salmon processing subcategory. The provisions of this subpart...

  7. 40 CFR 408.200 - Applicability; description of the Alaskan bottom fish processing subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Alaskan bottom fish processing subcategory. 408.200 Section 408.200 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Alaskan Bottom Fish Processing Subcategory § 408.200 Applicability; description of the Alaskan bottom fish processing subcategory. The provisions of this subpart are...

  8. 40 CFR 408.200 - Applicability; description of the Alaskan bottom fish processing subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Alaskan bottom fish processing subcategory. 408.200 Section 408.200 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Alaskan Bottom Fish Processing Subcategory § 408.200 Applicability; description of the Alaskan bottom fish processing subcategory. The provisions of this subpart are...

  9. 40 CFR 408.200 - Applicability; description of the Alaskan bottom fish processing subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Alaskan bottom fish processing subcategory. 408.200 Section 408.200 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Alaskan Bottom Fish Processing Subcategory § 408.200 Applicability; description of the Alaskan bottom fish processing subcategory. The provisions of this subpart are...

  10. 40 CFR 408.310 - Applicability; description of the Alaskan herring fillet processing subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Alaskan herring fillet processing subcategory. 408.310 Section 408.310 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Alaskan Herring Fillet Processing Subcategory § 408.310 Applicability; description of the Alaskan herring fillet processing subcategory. The provisions of this subpart...

  11. 40 CFR 408.320 - Applicability; description of the non-Alaskan herring fillet processing subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...-Alaskan herring fillet processing subcategory. 408.320 Section 408.320 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Non-Alaskan Herring Fillet Processing Subcategory § 408.320 Applicability; description of the non-Alaskan herring fillet processing subcategory. The provisions of this subpart...

  12. 40 CFR 408.320 - Applicability; description of the non-Alaskan herring fillet processing subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...-Alaskan herring fillet processing subcategory. 408.320 Section 408.320 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Non-Alaskan Herring Fillet Processing Subcategory § 408.320 Applicability; description of the non-Alaskan herring fillet processing subcategory. The provisions of this subpart...

  13. 40 CFR 408.320 - Applicability; description of the non-Alaskan herring fillet processing subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...-Alaskan herring fillet processing subcategory. 408.320 Section 408.320 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Non-Alaskan Herring Fillet Processing Subcategory § 408.320 Applicability; description of the non-Alaskan herring fillet processing subcategory. The provisions of this subpart...

  14. 40 CFR 408.310 - Applicability; description of the Alaskan herring fillet processing subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Alaskan herring fillet processing subcategory. 408.310 Section 408.310 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Alaskan Herring Fillet Processing Subcategory § 408.310 Applicability; description of the Alaskan herring fillet processing subcategory. The provisions of this subpart...

  15. 40 CFR 408.310 - Applicability; description of the Alaskan herring fillet processing subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Alaskan herring fillet processing subcategory. 408.310 Section 408.310 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Alaskan Herring Fillet Processing Subcategory § 408.310 Applicability; description of the Alaskan herring fillet processing subcategory. The provisions of this subpart...

  16. 40 CFR 408.310 - Applicability; description of the Alaskan herring fillet processing subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Alaskan herring fillet processing subcategory. 408.310 Section 408.310 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Alaskan Herring Fillet Processing Subcategory § 408.310 Applicability; description of the Alaskan herring fillet processing subcategory. The provisions of this subpart...

  17. 40 CFR 408.320 - Applicability; description of the non-Alaskan herring fillet processing subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...-Alaskan herring fillet processing subcategory. 408.320 Section 408.320 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Non-Alaskan Herring Fillet Processing Subcategory § 408.320 Applicability; description of the non-Alaskan herring fillet processing subcategory. The provisions of this subpart...

  18. 40 CFR 408.310 - Applicability; description of the Alaskan herring fillet processing subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Alaskan herring fillet processing subcategory. 408.310 Section 408.310 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Alaskan Herring Fillet Processing Subcategory § 408.310 Applicability; description of the Alaskan herring fillet processing subcategory. The provisions of this subpart...

  19. 40 CFR 408.320 - Applicability; description of the non-Alaskan herring fillet processing subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...-Alaskan herring fillet processing subcategory. 408.320 Section 408.320 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Non-Alaskan Herring Fillet Processing Subcategory § 408.320 Applicability; description of the non-Alaskan herring fillet processing subcategory. The provisions of this subpart...

  20. 40 CFR 408.90 - Applicability; description of the non-remote Alaskan shrimp processing subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...-remote Alaskan shrimp processing subcategory. 408.90 Section 408.90 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Non-Remote Alaskan Shrimp Processing Subcategory § 408.90 Applicability; description of the non-remote Alaskan shrimp processing subcategory. The provisions of this subpart...

  1. 40 CFR 408.100 - Applicability; description of the remote Alaskan shrimp processing subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... remote Alaskan shrimp processing subcategory. 408.100 Section 408.100 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Remote Alaskan Shrimp Processing Subcategory § 408.100 Applicability; description of the remote Alaskan shrimp processing subcategory. The provisions of this subpart are...

  2. 40 CFR 408.100 - Applicability; description of the remote Alaskan shrimp processing subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... remote Alaskan shrimp processing subcategory. 408.100 Section 408.100 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Remote Alaskan Shrimp Processing Subcategory § 408.100 Applicability; description of the remote Alaskan shrimp processing subcategory. The provisions of this subpart are...

  3. 40 CFR 408.90 - Applicability; description of the non-remote Alaskan shrimp processing subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...-remote Alaskan shrimp processing subcategory. 408.90 Section 408.90 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Non-Remote Alaskan Shrimp Processing Subcategory § 408.90 Applicability; description of the non-remote Alaskan shrimp processing subcategory. The provisions of this subpart...

  4. 40 CFR 408.100 - Applicability; description of the remote Alaskan shrimp processing subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... remote Alaskan shrimp processing subcategory. 408.100 Section 408.100 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Remote Alaskan Shrimp Processing Subcategory § 408.100 Applicability; description of the remote Alaskan shrimp processing subcategory. The provisions of this subpart are...

  5. 40 CFR 408.90 - Applicability; description of the non-remote Alaskan shrimp processing subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...-remote Alaskan shrimp processing subcategory. 408.90 Section 408.90 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Non-Remote Alaskan Shrimp Processing Subcategory § 408.90 Applicability; description of the non-remote Alaskan shrimp processing subcategory. The provisions of this subpart...

  6. 40 CFR 408.90 - Applicability; description of the non-remote Alaskan shrimp processing subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...-remote Alaskan shrimp processing subcategory. 408.90 Section 408.90 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Non-Remote Alaskan Shrimp Processing Subcategory § 408.90 Applicability; description of the non-remote Alaskan shrimp processing subcategory. The provisions of this subpart...

  7. 40 CFR 408.100 - Applicability; description of the remote Alaskan shrimp processing subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... remote Alaskan shrimp processing subcategory. 408.100 Section 408.100 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Remote Alaskan Shrimp Processing Subcategory § 408.100 Applicability; description of the remote Alaskan shrimp processing subcategory. The provisions of this subpart are...

  8. 40 CFR 408.90 - Applicability; description of the non-remote Alaskan shrimp processing subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...-remote Alaskan shrimp processing subcategory. 408.90 Section 408.90 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Non-Remote Alaskan Shrimp Processing Subcategory § 408.90 Applicability; description of the non-remote Alaskan shrimp processing subcategory. The provisions of this subpart...

  9. 40 CFR 408.100 - Applicability; description of the remote Alaskan shrimp processing subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... remote Alaskan shrimp processing subcategory. 408.100 Section 408.100 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Remote Alaskan Shrimp Processing Subcategory § 408.100 Applicability; description of the remote Alaskan shrimp processing subcategory. The provisions of this subpart are...

  10. 40 CFR 408.160 - Applicability; description of the Alaskan hand-butchered salmon processing subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Alaskan hand-butchered salmon processing subcategory. 408.160 Section 408.160 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Alaskan Hand-Butchered Salmon Processing Subcategory § 408.160 Applicability; description of the Alaskan hand-butchered salmon processing subcategory. The provisions of this subpart...

  11. 40 CFR 408.160 - Applicability; description of the Alaskan hand-butchered salmon processing subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Alaskan hand-butchered salmon processing subcategory. 408.160 Section 408.160 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Alaskan Hand-Butchered Salmon Processing Subcategory § 408.160 Applicability; description of the Alaskan hand-butchered salmon processing subcategory. The provisions of this subpart...

  12. 40 CFR 408.160 - Applicability; description of the Alaskan hand-butchered salmon processing subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Alaskan hand-butchered salmon processing subcategory. 408.160 Section 408.160 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Alaskan Hand-Butchered Salmon Processing Subcategory § 408.160 Applicability; description of the Alaskan hand-butchered salmon processing subcategory. The provisions of this subpart...

  13. 40 CFR 408.160 - Applicability; description of the Alaskan hand-butchered salmon processing subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Alaskan hand-butchered salmon processing subcategory. 408.160 Section 408.160 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Alaskan Hand-Butchered Salmon Processing Subcategory § 408.160 Applicability; description of the Alaskan hand-butchered salmon processing subcategory. The provisions of this subpart...

  14. 40 CFR 408.160 - Applicability; description of the Alaskan hand-butchered salmon processing subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Alaskan hand-butchered salmon processing subcategory. 408.160 Section 408.160 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Alaskan Hand-Butchered Salmon Processing Subcategory § 408.160 Applicability; description of the Alaskan hand-butchered salmon processing subcategory. The provisions of this subpart...

  15. Thematic mapper study of Alaskan ophiolites

    NASA Technical Reports Server (NTRS)

    Bird, John M.

    1988-01-01

    The two principle objectives of the project Thematic Mapper Study of Alaskan Ophiolites were to further develop techniques for producing geologic maps, and to study the tectonics of the ophiolite terrains of the Brooks Range and Ruby Geanticline of northern Alaska. Ophiolites, sections of oceanic lithosphere emplaced along island arcs and continental margins, are important to the understanding of mountain belt evolution. Ophiolites also provide an opportunity to study the structural, lithologic, and geochemical characteristics of ocean lithosphere, yielding a better understanding of the processes forming lithosphere. The first part of the report is a description of the methods and results of the TM mapping and gravity modeling. The second part includes papers being prepared for publication. These papers are the following: (1) an analysis of basalt spectral variations; (2) a study of basalt geochemical variations; (3) an examination of the cooling history of the ophiolites using radiometric data; (4) an analysis of shortening produced by thrusting during the Brooks Range orogeny; and (5) a study of an ophiolite using digital aeromagnetic and topographic data. Additional papers are in preparation.

  16. New Perspectives of Permafrost Distribution and its Influence on Groundwater Flow and Ecosystem Performance for the Yukon Flats Area, Northern Alaska

    NASA Astrophysics Data System (ADS)

    Smith, B. D.; Walvoord, M. A.; Wylie, B. K.; Voss, C. I.; Pastick, N.; Minsley, B. J.; Jepsen, S. M.; Jorgenson, T. T.; Cannia, J. C.; Abraham, J. D.; Anderson, L.

    2011-12-01

    Permafrost is a predominant physical feature of the planet's Arctic and sub-Arctic regions and a major consideration that impacts climate processes, ecosystem function, water resources, and infrastructure engineering. The U.S. Geological Survey has conducted hydrological, geophysical, and geological studies of the Yukon Flats area within the discontinuous permafrost region of Interior Alaska. This is an area of low topographic relief that is populated with numerous streams, lakes and the braided meandering Yukon River with broad gravel-filled channels. Lake sediments and geological archives contain preserved sedimentary records of landscape changes in ecosystems, climate, and groundwater at decade-to-century and millennial time scales. The near-surface geology consists of unconsolidated Pliocene lacustrine silts and clays overlain by late Pleistocene and Holocene alluvial gravels and eolian deposits including extensive loess uplands and dunes. Remotely sensed data for the area from a variety of sensors provide information that is used for both static image interpretations and dynamic process modeling. An airborne electromagnetic survey (AEM) carried out in June of 2010 covered a large area (~1,800 line-km) with widely spaced reconnaissance lines and a 10 by 30 km block near Ft. Yukon. The AEM survey data was inverted to produce resistivity as a function of depth along the flight lines. The resistivity depth sections map the presence or absence of permafrost both laterally and with depth, as well as variations in subsurface lithology. The resulting depth images provide a unique detailed view of the subsurface that has previously only been conceptualized. One application of the remotely sensed data is to extrapolate the AEM data and interpretation between flight lines. Model development and independent test accuracies for 0-1 m electrical resistivity had training and test R2 values of 0.90 and 0.87 indicating accurate prediction models. Groundwater modeling of the

  17. Palaeomagnetism of the Howards Pass Zn-Pb deposits, Yukon, Canada

    NASA Astrophysics Data System (ADS)

    Kawasaki, K.; Symons, D. T. A.

    2012-07-01

    The Howards Pass district is located in the Selwyn Basin, Yukon. The district consists of >15 laminated clastic-dominated (CD) sphalerite-galena (Zn-Pb) deposits in the 'zinc corridor' that trends northwest-southeast and extends for ˜35 km. The stratiform mineralized zone, the Active Member, is hosted in carbonaceous cherts and black shales of the Early Silurian Road River Group. Using mostly thermal and then alternating field step demagnetization isolated a stable characteristic remanent magnetization (ChRM) by the core-magnetization-angle method from 18 sites (339 specimens) in 18 variably oriented exploration drill hole cores from 6 Zn-Pb mineralized panels. Rock magnetic analyses show that the main remanence carriers are single- or pseudosingle-domain pyrrhotite and titanomagnetite. The deposits' mean ChRM direction yields a pole position of either ˜170 Ma on the North American apparent polar wander path or ˜162 Ma on a corrected path for the Intermontane Belt (IMB) terranes. A negative palaeomagnetic fold test indicates that the mineralization's ChRM is post-folding, setting a minimum age for regional metamorphic deformation of ˜170 ± 20 Ma and supporting an Early Jurassic arrival for the IMB's collision and accretion to North America. An autochthonous or para-autochthonous North American tectonic model is favoured for the ChRM of the metamorphosed Selwyn Basin strata rather than an allochthonous IMB model. Further, the palaeomagnetic age indicates that the coarse-grained Zn-Pb mineralization in fine fractures that cut the laminated fine-grained Zn-Pb mineralization at Howards Pass at least was formed by remobilization during Middle Jurassic metamorphism.

  18. Late Pleistocene and Holocene tephrostratigraphy of interior Alaska and Yukon: Key beds and chronologies over the past 30,000 years

    NASA Astrophysics Data System (ADS)

    Davies, Lauren J.; Jensen, Britta J. L.; Froese, Duane G.; Wallace, Kristi L.

    2016-08-01

    The Aleutian Arc-Alaska Peninsula and Wrangell volcanic field are the main source areas for tephra deposits found across Alaska and northern Canada, and increasingly, tephra from these eruptions have been found further afield in North America, Greenland, and Europe. However, there have been no broad scale reviews of the Late Pleistocene and Holocene tephrostratigraphy for this region since the 1980s, and this lack of data is hindering progress in identifying these tephra both locally and regionally. To address this gap and the variable quality of associated geochemical and chronological data, we undertake a detailed review of the latest Pleistocene to Holocene tephra found in interior Alaska and Yukon. This paper discusses nineteen tephra that have distributions beyond southwest Alaska and that have the potential to become, or already are, important regional markers. This includes three 'modern' events from the 20th century, ten with limited data availability but potentially broad distributions, and six that are widely reported in interior Alaska and Yukon. Each tephra is assessed in terms of chronology, geochemistry and distribution, with new Bayesian age estimates and geochemical data when possible. This includes new major-element geochemical data for Crater Peak 1992, Redoubt 1989-90, and two andesitic tephra from St Michael Island (Tephra D), as well as revised age estimates for Dawson tephra, Oshetna, Hayes set H, Aniakchak CFE II, and the White River Ashes, northern and eastern lobes.

  19. Minor and trace element composition and age of Yukon probable-microtektites

    NASA Technical Reports Server (NTRS)

    Boundy-Sanders, S. Q.; Hervig, R. L.

    1993-01-01

    Major, minor, and trace element composition of the candidate micro tektites from Yukon Territory suggest a possible impact site of hydrothermally altered limestone and sand or chert, or possibly a carbonatite. Their REE/chondrite curve is similar in character to, but higher than, shale composites of North America, Australia, and Europe. Relative to these same composites, the Yukon droplets are enriched in Y, F, S, Sr, P, Mn, Mg, and Ca. They are depleted in Rb, Li, Th, Nb, Ti, K, Na, Fe, Si, and Al. Biostratigraphic constraints on the droplets indicate they are Middle to Late Devonian, more likely Middle Devonian, in age.

  20. Regional, temporal, and species patterns of mercury in Alaskan seabird eggs: mercury sources and cycling or food web effects?

    PubMed

    Day, Rusty D; Roseneau, David G; Vander Pol, Stacy S; Hobson, Keith A; Donard, Olivier F X; Pugh, Rebecca S; Moors, Amanda J; Becker, Paul R

    2012-07-01

    Mercury concentration ([Hg]), δ(15)N, and δ(13)C values were measured in eggs from common murres (Uria aalge), thick-billed murres (U. lomvia), glaucous gulls (Larus hyperboreus), and glaucous-winged gulls (L. glaucescens) collected in Alaska from 1999 to 2005. [Hg] was normalized to a common trophic level using egg δ(15)N values and published Hg trophic magnification factors. Egg [Hg] was higher in murres from Gulf of Alaska, Cook Inlet, and Norton Sound regions compared to Bering Sea and Bering Strait regions, independent of trophic level. We believe the Yukon River outflow and terrestrial Hg sources on the southern Seward Peninsula are responsible for the elevated [Hg] in Norton Sound eggs. Normalizing for trophic level generally diminished or eliminated differences in [Hg] among taxa, but temporal variability was unrelated to trophic level. Normalizing murre egg [Hg] by trophic level improves the confidence in regional comparisons of Hg sources and biogeochemical cycling in Alaska. PMID:22522226

  1. Definition of Alaskan Aviation Training Requirements. Final Report.

    ERIC Educational Resources Information Center

    Mitchell, M. K.; And Others

    Because of high accident rates and the unique conditions faced in Arctic flying, a project was conducted to develop a training program for airline pilots flying over Alaska. Data were gathered, through the critical incident method in conjunction with traditional job-analysis procedures, about how experienced Alaskan pilots learned to cope with the…

  2. A new tymovirus from a native Alaskan plant, Mertensia paniculata

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Diseased plants growing at the interface of managed and natural ecosystems may provide reservoirs for spread of diverse plant viruses into domestic and native plants. Mertensia paniculata (Ait.) G. Don, family Boraginaceae, is a native Alaskan plant that is naturally distributed along roadsides, in ...

  3. Standard Implications: Alaskans Reflect on a Movement To Change Teaching.

    ERIC Educational Resources Information Center

    Calkins, Annie, Ed.; Christian, Scott, Ed.

    In this anthology, rural Alaskan English teachers in the Bread Loaf Rural Teacher Network describe their experiences implementing new state education standards while continuing their commitment to learner-centered and place-based practice. The book presents narratives about teaching grounded in knowledge and understanding of students and…

  4. RESIDUAL MUTAGENICITY OF THE ALASKAN OIL SPILL ORGANICS

    EPA Science Inventory

    RESIDUAL MUTAGENICITY OF THE ALASKAN OIL SPILL ORGANICS. L.D.

    The Exxon Valdez, on March 24, 1989, spilled approximately eleven million gallons of Prudhoe Bay crude oil into the waters of Prince William Sound. Approximately 300 miles of
    contaminated beach are potential...

  5. Effects of the Oil Spill on Alaskan Education.

    ERIC Educational Resources Information Center

    Oldaker, Lawrence Lee

    Oil-industry-produced revenues, help finance Alaskan state and local governmental services including education. Capital losses incurred by the Exxon Corporation and by commerical fisheries as a consequence of the Exxon Valdez oil spill caused an economic recession, the result being diminished financing for a number of governmental programs and…

  6. Rural Alaskan Schools: Educational Specifications. Reprinted September, 1971.

    ERIC Educational Resources Information Center

    Alaska State Dept. of Education, Juneau. Office of Public Information and Publications.

    The educational specifications of facilities for rural Alaskan schools are given in this 1964 report. Alaska's 6 recognized geographic regions are briefly described with consideration to topography, climate, permafrost conditions, latitude position, and transportation difficulties which present problems in planning schools. Since the school design…

  7. Village Science: A Resource Handbook for Rural Alaskan Teachers.

    ERIC Educational Resources Information Center

    Dick, Alan

    A resource handbook for rural Alaskan teachers covers village science, to make basic science concepts relevant to the physical environment in villages. Material is intended for use as filler for weeks that come up short on science materials, to provide stimulation for students who cannot see the relevance of science in their lives, and to help…

  8. Rural Alaskan High School Boys' and Girls' Attitudes toward Education.

    ERIC Educational Resources Information Center

    Chu, Lily; Culbertson, Jeanne

    Questionnaires were administered to 73 sophomore and senior high school students in 3 isolated rural Alaska towns (Adak, Unalaska, and Dillingham) to study the effects of socio-economic factors on rural Alaskan youth's educational aspirations and expectations. Because of a military-supported economy, Adak was a typical middle class American…

  9. STARS (Secondary Training for Alaskan Rural Students): Communications. Draft Copy.

    ERIC Educational Resources Information Center

    Griffin, Elaine; Opel, Kathleen

    The STARS (Secondary Training for Alaskan Rural Students) materials resulted from extensive rewriting of the Vocational Adult Secondary Training (VAST) materials produced by the British Columbia Department of Education, after those materials had been used with the 9th and 10th grades on Kodiak Island. Revision was done by teachers who had been…

  10. Alaskan Manpower and the Petroleum-Related Workforce.

    ERIC Educational Resources Information Center

    Bland, Laurel L.

    This article, in two parts, presents information as a foundation for an integrated approach to utilization and employment of Alaskan manpower in the construction and maintenance of the trans-Alaska pipeline, and the continuing exploration and development of the petroleum fields. The four primary manpower sources for petroleum related employment in…

  11. SOME EFFECTS OF PETROLEUM ON NEARSHORE ALASKAN MARINE ORGANISMS

    EPA Science Inventory

    The overall objective of this project was to better understand the effects of chronic, low-level oil pollution on nearshore Alaskan marine organisms. The bivalve mollusc Macoma balthica accumulated hydrocarbons during 180 days of continuous exposure to Prudhoe Bay crude oil in fl...

  12. Leaders' perspectives in the Yellowstone to Yukon Conservation Initiative

    USGS Publications Warehouse

    Mattson, D.J.; Clark, S.G.; Byrd, K.L.; Brown, S.R.; Robinson, B.

    2011-01-01

    The Yellowstone to Yukon Conservation Initiative (Y2Y) was created in 1993 to advance conservation in a 1.2 million km2 portion of the North American Rocky Mountains. We assembled 21 people with influence over Y2Y in a workshop to elucidate perspectives on challenges and solutions for this organization at a key point in its evolution, and used Q method to define four perspectives on challenges and three on solutions. Participants were differentiated by four models for effecting change-vision-based advocacy, practice-based learning, political engagement, and scientific management-with emphasis on the first three. Those with authority in Y2Y aligned with vision-based advocacy and expressed ambivalence about practice-based adaptive learning and rigorous appraisals of existing strategies. Workshop results were consistent with an apparent trend toward organizational maturation focused on stabilizing revenues, developing formal organizational arrangements, and focusing strategies. Consolidation of power in Y2Y around a long-standing formula does not bode well for the effectiveness of Y2Y. We recommend that leaders in Y2Y and similar organizations focused on large-scale conservation to create and maintain an open system-philosophically and operationally-that capitalizes on the diverse perspectives and skills of individuals who are attracted to such efforts. We also recommend that the Y2Y initiative be followed closely to harvest additional lessons for potential application to large-scale conservation efforts elsewhere. ?? Springer Science+Business Media, LLC(outside the USA).2011.

  13. Impact of the Yakutat indentor corner on present-day tectonics and fault activity in SE Alaska - SW Yukon

    NASA Astrophysics Data System (ADS)

    Mazzotti, S.; Marechal, A.; Ritz, J. F.; Ferry, M. A.

    2015-12-01

    We present an active tectonic model of the SE Alaska - SW Yukon region based principally on the integration of recent GPS velocity data and new fault-slip rates derived from geomorphology. In this region, the Yakutat collision results in complex tectonics with patterns of strain localization and strain partitioning that strongly vary across the various mountain ranges and active faults. We propose that deformation and fault activity in the St. Elias and Chugach Mountains are primarily controlled by the eastern syntaxis of the Yakutat collision, which produces a semi-radial tectonic pattern: Velocities, principal horizontal shortening rates, and maximum horizontal stress orientations rotate by 60 - 80 ° around the syntaxis, from roughly parallel to the relative Pacific - North America motion at the front of the collision to roughly orthogonal southeast of the syntaxis. The interaction between this strain pattern and major inherited tectonic structures inland of the collision zone (i.e., Denali and Duke River Faults) results in various reactivation modes of these structures. Specifically, the Denali Fault shows a very pronounced lateral variations of activity from ~12 mm/a of dextral slip rate in its central section to ~1 mm/a of mostly shortening slip rate along its southern section. This marked change of activity is associated with a possible relay system where the Duke River and Totschunda Faults accommodate a major part (8 - 12 mm/a) of the inland strain transfer directly in front of the syntaxis. This new tectonic model retains some questions, in particular regarding the mechanisms of deformation and strain transfer (1) from the syntaxis to the Duke River - Totschunda system and (2) at the junction between Totschunda and Denali Faults. Numerical models of present-day deformation may help address these issues and provide information about relative strength of the various crustal and inherited fault elements of this system.

  14. Defining Educational Leadership in Canada's Yukon Territory: "Hmmm, that's a Good Question..."

    ERIC Educational Resources Information Center

    Blakesley, Simon

    2011-01-01

    Studies examining educational leadership in northern Canada appear rare. Therefore, the purpose of this article is to present findings from a 2010 study of educational leadership in Canada's Yukon Territory. The study adopts a critical ethnographic approach to unpack educational leadership as construed and enacted by two male and two female…

  15. Storytelling as an Insightful Tool for Understanding Educational Leadership in Indigenous Yukon Contexts

    ERIC Educational Resources Information Center

    Blakesley, Simon

    2010-01-01

    This article is based upon a 2006 review of the research methodologies identified in the articles of two educational leadership journals. It found the use of narrative and biographical approaches specific to the field of educational leadership appears rare. This article examines the stories told by Yukon school principals in Indigenous contexts to…

  16. Effect of permafrost thaw on the dynamics of lakes recharged by ice-jam floods: case study in Yukon Flats, Alaska

    USGS Publications Warehouse

    Steve M. Jepsen; Walvoord, Michelle Ann; Voss, Clifford I.; Rover, Jennifer R.

    2015-01-01

    Large river floods are a key water source for many lakes in fluvial periglacial settings. Where permeable sediments occur, the distribution of permafrost may play an important role in the routing of floodwaters across a floodplain. This relationship is explored for lakes in the discontinuous permafrost of Yukon Flats, interior Alaska, using an analysis that integrates satellite-derived gradients in water surface elevation, knowledge of hydrogeology, and hydrologic modeling. We observed gradients in water surface elevation between neighboring lakes ranging from 0.001 to 0.004. These high gradients, despite a ubiquitous layer of continuous shallow gravel across the flats, are consistent with limited groundwater flow across lake basins resulting from the presence of permafrost. Permafrost impedes the propagation of floodwaters in the shallow subsurface and constrains transmission to “fill-and-spill” over topographic depressions (surface sills), as we observed for the Twelvemile-Buddy Lake pair following a May 2013 ice-jam flood on the Yukon River. Model results indicate that permafrost table deepening of 1–11 m in gravel, depending on watershed geometry and subsurface properties, could shift important routing of floodwater to lakes from overland flow (fill-and-spill) to shallow groundwater flow (“fill-and-seep”). Such a shift is possible in the next several hundred years of ground surface warming, and may bring about more synchronous water level changes between neighboring lakes following large flood events. This relationship offers a potentially useful tool, well-suited to remote sensing, for identifying long-term changes in shallow groundwater flow resulting from thawing of permafrost.

  17. Burial, incineration solve Alaskan PCB contamination

    SciTech Connect

    Ives, J.A. ); Young, D.T. )

    1989-10-01

    Polychlorinated biphenyl (PCB) remediation at Alaska's Swanson River has excavated more than 80,000 tons of PCB-contaminated soil and isolated it in bermed and lined stock-piles. In addition, incineration of other PCB-contaminated materials has been carried out safely. This article on the site reviews its history and part of its remediation approaches.

  18. Inferring groundwater contributions and pathways to streamflow during snowmelt over multiple years in a discontinuous permafrost subarctic environment (Yukon, Canada)

    NASA Astrophysics Data System (ADS)

    Carey, Sean K.; Boucher, Jessica L.; Duarte, Celina M.

    2013-02-01

    Research on large northern rivers suggests that as permafrost thaws, deeper groundwater flowpaths become active, resulting in greater baseflow, increased concentrations of weathering ions and reduced concentrations of dissolved organic carbon in the streamflow. In contrast, at the headwater-catchment scale, where understanding of groundwater/surface-water interactions is developed, inter-annual variability in climate and hydrology result in complex hydrological and chemical responses to change. This paper reports on a 4-year runoff investigation in an alpine discontinuous permafrost environment in Yukon, Canada, using stable isotopes, major dissolved ions and hydrometric data, to provide enhanced insight into the inter-annual-variability runoff-generation processes. Stable isotope results suggest that pre-event (old) water stored within the catchment dominates the snowmelt hydrograph, and dissolved ion results reveal that groundwater pathways occur predominantly in the near-surface during freshet. Dissolved organic carbon varies inter-annually, reflecting changing melt patterns, whereas weathering ions generated from deeper flowpaths become diluted. The total snow-water equivalent does not have a major influence on the fraction of snowmelt water reaching the stream or the runoff ratio. Results from multiple years highlight the considerable variability over short time scales, limiting our ability to detect climate-change influences on groundwater at the headwater scale.

  19. Low Temperature Paleogene Thermal Evolution of the British Mountains using Apatite U-Th/He Dating, Northern Yukon, Canada

    NASA Astrophysics Data System (ADS)

    Pickering, J. E.; Guest, B.; Schneider, D. A.; Lane, L.

    2014-12-01

    The age and rate of exhumation of the British Mountains is tied to the timing of deformation in the Beaufort Sea, an active site for hydrocarbon exploration. This region contains a large portion of North America's oil and gas reserves. The British Mountains, the eastern extent of the Brooks Range in Alaska, include Paleogene structures that are the onshore portion of the Beaufort fold belt. In the Beaufort Sea, deformation is dominated by thin-skinned folding and thrusting of Paleocene to Oligocene sediments that is sourced from the British Mountains. Onshore, Paleogene deformation overprints multiple older structural events. The low temperature time history of the onshore Paleogene structures will be determined through U-Th/He dating of apatites (AHe). The results will contribute to better understanding of the timing of the maturation and migration of hydrocarbons in the Beaufort Sea. Previous work on the thermal history of northern Yukon and the North Slope of Alaska provides a regional framework for the region's low temperature-time history. These regional studies of the northern Yukon and Alaska yielded Paleocene to Eocene (60Ma - 40Ma) apatite fission track (AFT) cooling ages that progressively young to the north, consistent with geological evidence for northward propagating deformation. The British Mountains consist of Neoproterozoic to early Paleozoic marine sediments that are intruded by scattered Devonian plutons; both rock types will be included in the study. This study aims to improve the understanding of the Paleogene tectonic activity of the British Mountains and the deformation history of the Beaufort fold belt. The two data sets, existing AFT and new AHe results, will be both be included in the interpretation of the study area. We will present AHe data to better constrain the onshore exhumation and deformation rates at low temperatures (~60-90°C). A sampled transect through the British mountains, along the Firth River valley will provide good

  20. Pleistocene Permafrost Thawing History of Alaska, the Yukon, and the Northwest Territories from U-Th Dating of Cave Speleothems

    NASA Astrophysics Data System (ADS)

    Biller, N.; Shakun, J. D.; McGee, D.; Hardt, B. F.; Ford, D.; Lauriol, B.

    2015-12-01

    Permafrost, or permanently frozen ground, is widespread in the Arctic and contains twice as much carbon as the atmosphere in the form of frozen organic matter. This carbon may be vulnerable to thaw and release to the atmosphere as methane under a warming climate, making permafrost thaw one of the potentially most significant amplifying feedbacks to anthropogenic warming. Nonetheless, permafrost can be slow to respond to warming, the short instrumental record may not adequately capture long-term trends, and the modest temperature changes of the past few millennia provide poor analogues to understand the possibility of crossing climate thresholds in the next century or beyond. One way to address this problem is to assess the stability of permafrost during previous interglacial periods of varying levels of warmth, which provide natural experiments to examine the Arctic's sensitivity to warming. Cave speleothems in the Arctic are relics of past periods of thaw that enabled meteoric water to seep into caves and deposit calcite. We employed uranium-thorium (U-Th) dating to constrain the chronology and extent of permafrost thaw in the North American Arctic during the past 600,000 years. We sampled caves from a range of permafrost zones and latitudes, including the Fishing Branch Territorial Park, Yukon (66.5°N, continuous permafrost), White Mountains National Recreation Area, Alaska (65°N, discontinuous permafrost), Yukon-Charley Rivers National Preserve, Alaska (64.5°N, discontinuous permafrost), and Nahanni National Park Reserve, Northwest Territories (62°N, discontinuous permafrost). Thirty-five samples from 30 speleothems have been analyzed at this point, with 23 samples lying beyond the U-Th dating range, and finite ages tending to cluster near Marine Isotope Stage 11 (MIS 11) within uncertainty, as well as perhaps MIS 9, 13, and 15. This preliminary dataset, coupled with a similar study in Siberia (Vaks et al., 2013), is thus suggestive of an episode of

  1. Hereditary encephalomyelopathy and polyneuropathy in an Alaskan husky.

    PubMed

    Wakshlag, J J; de Lahunta, A

    2009-12-01

    An Alaskan husky puppy was examined for a neurologic disease which began at six weeks of age with generalised paresis that progressed resulting in recumbency by 18 weeks. Thoracic limbs primarily exhibited lower motor neuron signs that included distal muscle atrophy and persistent elbow and carpal flexion that resisted manual extension. Pelvic limb signs primarily exhibited upper motor neuron and general proprioceptive deficits, but also included lower motor neuron signs. Abnormal vocalisation suggested a laryngeal paresis. Histopathologic lesions included a diffuse axonopathy and secondary demyelination in the nerves of the limbs and larynx and a similar bilaterally symmetrical degeneration in the spinal cord white matter suggestive of a dying back axonopathy. In addition, a degenerative process was present in nuclei in the brain stem and cerebellum. Recognition of this disease through clinical and pathologic examination in other related Alaskan Huskies suggested an autosomal recessive inherited disorder. PMID:19954445

  2. Revegetation of Alaskan coal mine spoils. Progress report

    SciTech Connect

    Mitchell, W W; Mitchell, G A; McKendrick, J D

    1980-05-23

    Activities initiated after the start of the revegetation project on Alaskan coal mine spoils on September 1, 1979 have consisted mainly of some fall plantings (dormant seedings) and soil and coal spoil samplings and analyses. Because of the late summer start for the project, only a limited amount of field work could be initiated in plant material studies. This consisted of a fall planting at the Usibelli mine site at Healy in interior Alaska. The planting was intended to test the efficacy of seeding in the frost period following the growing season, requiring the seed to remain dormant over winter and to germinate when conditions become favorable in late spring. It also was intended as a comparison of a number of different grasses. Thirty entries were seeded in three replications. Fifteen species of grasses and a clover were included in the trial. The site provided for the trial was on overburden material along a streambed. Among the entries were eight cultivars of introduced grasses, five cultivars of native Alaskan germplasm, one introduced clover cultivar, and sixteen experimental grasses mainly of Alaskan origin.

  3. Mesozoic thermal history and timing of structural events for the Yukon-Tanana Upland, east-central Alaska: 40Ar/39Ar data from metamorphic and plutonic rocks

    USGS Publications Warehouse

    Dusel-Bacon, C.; Lanphere, M.A.; Sharp, W.D.; Layer, P.W.; Hansen, V.L.

    2002-01-01

    We present new 40Ar/39Ar ages for hornblende, muscovite, and biotite from metamorphic and plutonic rocks from the Yukon-Tanana Upland, Alaska. Integration of our data with published 40Ar/39Ar, kinematic, and metamorphic pressure (P) and temperature (T) data confirms and refines the complex interaction of metamorphism and tectonism proposed for the region. The oldest metamorphic episode(s) postdates Middle Permian magmatism and predates the intrusion of Late Triassic (215-212 Ma) granitoids into the Fortymile River assemblage (Taylor Mountain assemblage of previous papers). In the eastern Eagle quadrangle, rapid and widespread Early Jurassic cooling is indicated by ???188-186 Ma 40Ar/39Ar plateau ages for hornblende from plutons that intrude the Fortymile River assemblage, and for metamorphic minerals from the Fortymile River assemblage and the structurally underlying Nasina assemblage. We interpret these Early Jurassic ages to represent cooling resulting from northwest-directed contraction that emplaced the Fortymile River assemblage onto the Nasina assemblage to the north as well as the Lake George assemblage to the south. This cooling was the final stage of a continuum of subduction-related contraction that produced crustal thickening, intermediate- to high-P metamorphism within both the Fortymile River assemblage and the structurally underlying Lake George assemblage, and Late Triassic and Early Jurassic plutonism in the Fortymile River and Nasina assemblages. Although a few metamorphic samples from the Lake George assemblage yield Jurassic 40Ar/39Ar cooling ages, most yield Early Cretaceous 40Ar/39Ar ages: hornblende ???135-115 Ma, and muscovite and biotite ???110-108 Ma. We interpret the Early Cretaceous metamorphic cooling, in most areas, to have resulted from regional extension and exhumation of the lower plate, previously tectonically thickened during Early Jurassic and older convergence.

  4. Fission-track ages of late Cenozoic distal tephra beds in the Yukon Territory and Alaska.

    USGS Publications Warehouse

    Naeser, N.D.; Westgate, J.A.; Hughes, O.L.; Pewe, T.L.

    1982-01-01

    Six distal tephra beds from the Yukon Territory and Alaska were dated by the fission-track method. Assuming that no track fading has occurred in the glass, Old Crow and Dawson tephra beds are <120 000 and <52 000 yr old, respectively. Mosquito Gulch tephra is 1.22 m.y. old, Fort Selkirk tephra is approx 1 m.y. old, the Ester ash bed is 0.45 m.y. old, and the best estimate of the age of Lost Chicken tephra is in the range 1.7-2.6 m.y. It is concluded that application of the fission-track method to distal tephra, in conjunction with detailed characterization studies, offers great potential for elucidation of the Late Cainozoic geological history of Alaska and the Yukon Territory. -P.Br.

  5. Further contributions to the aleocharine fauna of the Yukon Territory, Canada (Coleoptera, Staphylinidae)

    PubMed Central

    Klimaszewski, Jan; Godin, Benoit; Bourdon, Caroline

    2012-01-01

    Abstract The aleocharine beetles of the Yukon Territory, Canada are reviewed based on material studied since the most recent survey of the territory in 2008. The present contribution recognizes a fauna of 125 species, of which 9 are new to science, 20 represent new territorial records and one represents a new Canadian record. Seventeen species are considered Holarctic, 6 introduced, and 2 species are of undetermined status (Holarctic or adventive). The Yukon fauna is classified in 32 genera and 8 tribes. The new species are: 1) Acrotona horwoodae Klimaszewski & Godin, sp. n.; 2) Atheta (Microdota) microelytrata Klimaszewski & Godin, sp. n.; 3) Atheta (Microdota) riparia Klimaszewski & Godin, sp. n.; 4) Atheta (Datomicra) whitehorsensis Klimaszewski & Godin, sp. n.; 5) Ocyusa yukonensis Klimaszewski & Godin, sp. n.; 6) Philhygra pseudolarsoniKlimaszewski & Godin, sp. n.; 7) Philhygra terrestris Klimaszewski & Godin, sp. n.; 8) Boreophilia davidgei Klimaszewski & Godin, sp. n.; and 9) Boreophilia herschelensis Klimaszewski & Godin, sp. n. PMID:22577321

  6. Using remotely-sensed nearshore suspended sediment as an indicator of environmental change on the Alaskan North Slope

    NASA Astrophysics Data System (ADS)

    Hobson, Anne Carrie Hickey

    The effects of climate change are increasing the vulnerability the delicate Arctic system on the North Slope of Alaska. Concurrently, oil and gas development is projected to expand across the region, the wide-scale effects of which are largely unknown in a less-resilient system. This research provides the framework for using satellite data to assess and monitor suspended sediment conditions in the nearshore Alaskan Beaufort Sea, which provide a key indicator of environmental change. Satellite monitoring of suspended sediment levels provides a cost-effective means to obtain nearly real-time, synoptic information about environmental change on the North Slope. This information can be incorporated into cumulative effects analyses and enhance their capability to assess and predict the environmental effects of oil and gas development in a changing climate. Surface reflectance data from the Moderate Resolution Imaging Spectroradiometer (MODIS) and Advanced Very High Resolution Radiometer (AVHRR) sensors were calibrated to total suspended sediment (TSS) concentrations in the Alaskan Beaufort Sea and used to construct time series of proxy TSS data for 2000--2005 and 1981--2004, respectively. These time series produced a baseline quantifying the interannual variability and 24-year trends in median annual TSS concentrations at locations in the nearshore Alaskan Beaufort Sea. Increasing trends over the analysis period were identified in the outflow areas of the Ikpikpuk, Colville, Kuparuk and Sagavanirktok Rivers, as well as in Admiralty Bay. Additionally, TSS levels in 1994 and 2000 exceeded the normal range of variability at several of the nearshore locations investigated. Different areas along the nearshore had varying TSS magnitudes and modes of variability, a function of the terrestrial and nearshore processes controlling TSS conditions at each location. An empirical model explained 65 percent of the variability in annual median TSS values using precipitation factors that

  7. 40 CFR 408.220 - Applicability; description of the non-Alaskan mechanized bottom fish processing subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...-Alaskan mechanized bottom fish processing subcategory. 408.220 Section 408.220 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Non-Alaskan Mechanized Bottom Fish Processing Subcategory § 408.220 Applicability; description of the non-Alaskan mechanized bottom fish processing subcategory. The provisions...

  8. 40 CFR 408.220 - Applicability; description of the non-Alaskan mechanized bottom fish processing subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...-Alaskan mechanized bottom fish processing subcategory. 408.220 Section 408.220 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Non-Alaskan Mechanized Bottom Fish Processing Subcategory § 408.220 Applicability; description of the non-Alaskan mechanized bottom fish processing subcategory. The provisions...

  9. 40 CFR 408.210 - Applicability; description of the non-Alaskan conventional bottom fish processing subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...-Alaskan conventional bottom fish processing subcategory. 408.210 Section 408.210 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Non-Alaskan Conventional Bottom Fish Processing Subcategory § 408.210 Applicability; description of the non-Alaskan conventional bottom fish processing subcategory. The provisions...

  10. 40 CFR 408.210 - Applicability; description of the non-Alaskan conventional bottom fish processing subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...-Alaskan conventional bottom fish processing subcategory. 408.210 Section 408.210 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Non-Alaskan Conventional Bottom Fish Processing Subcategory § 408.210 Applicability; description of the non-Alaskan conventional bottom fish processing subcategory. The provisions...