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In Canada's subarctic?the boreal ecosystem that spans most of mainland Canada?the temperature is climbing, and the snowpack is thinning. Previous research has shown that snow is disappearing even faster than sea ice.
This thesis investigates snow-pack development and frost penetration in the Blackstone Uplands, Y.T. The purpose is to assess the use of an accessible reference site as an index of these conditions throughout the area. The project responds to local interest in improving management of snowmobile access to the region. Sixteen transects were monitored for snow depth in fall and winter 2006-07. Active-layer temperature was monitored by data logger during freeze-up. Below-normal snowfall permitted examination of snow-pack development with marginal conditions for snowmobile traffic. Prior to snow redistribution by wind, snow depth was controlled by elevation and the reference site had more snow than all valley-bottom...
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Previous studies indicate streams in the watershed of Anchorage, AK, contain elevated concentrations of several Potentially Toxic Metals (PTMs) in the water, suspended and streambed sediment and benthic macro invertebrates. This study investigated the sources, distribution, and uptake of PTMs by aquatic organisms in the watershed and their relationship to land-use patterns. Sampling sites were chosen that represent the watercourses of each of the four major streams in Anchorage. Water, streambed sediment, various species of benthic macroinvertebrates and slimy sculpin ( Cottus cognatus ) were collected throughout the summer of 2005. A lake sediment core was also collected from Campbell Lake to assess PTM deposition...
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The National Park Service (NPS) approved the use of Calcium Chloride as a dust suppressant on the Park road after four years of research. A formal monitoring program to track the spatial and temporal movement of CaCl2 concentrations along the Park road began in 2005. Fifteen terrestrial sites and fourteen water body locations were selected to monitor the movement of chloride from the roadbed into roadside soils and surface waters. Initial results showed wide variability in chloride concentrations in soil adjacent to the roadbed, while waterbodies generally had low concentrations (ABR 2006). This report presents 2007 results for the dust palliative chloride monitoring program.During the summer of 2007, 35 applications...
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The characteristics of sediment discharge in the Yukon River, Alaska were investigated by monitoring water discharge, water turbidity and water temperature. The river-transported sediment, 90 wt.% or more, consists of silt and clay (grain size less than or equal to 62.5 mum), which probably originated in the glacier-covered mountains mostly in the Alaska Range. For early June to late August 1999, we continuously measured water turbidity and temperature near the estuary and in the middle of Yukon River by using self-recording turbidimeters and temperature data loggers. The water turbidity (ppm) was converted to suspended sediment concentration (SSC; mg/l) of river water, using a relation between simultaneous turbidity...
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White phosphorus (WP) has been implicated in the deaths of thousands of waterfowl annually at Eagle River Flats (ERF), an estuarine salt marsh located on Fort Richardson near Anchorage, Alaska. The source of WP contamination at ERF was the firing of WP containing munitions into the area by the U.S. military. WP is a well-known toxicant and is lethal to a wide range of species. However, WP contamination at ERF is the first documented case of a U.S. Army munitions impact area contaminated with WP particles. This has led to the designation of ERF as a Superfund site by the U.S. Environmental Protection Agency, and the Army must follow the guidelines of remediation set by the Comprehensive Environmental Response, Compensation,...
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Control of surface and subsurface water is a critical factor in the efficiency of remediation efforts at Eagle River Flats, an active impact range on Fort Richardson, Alaska, contaminated with particulate white phosphorus from artillery and mortar rounds. The Flats is an estuarine salt marsh bordered by bluffs with water groundwater influx from the edges as well as periodic tidal and river inundation and rain events. The uneven topography and presence of numerous craters results in pooled surface water and high perched water levels, inhibiting remediation of the contaminant. Pumps are used to drain contaminated areas to enhance remediation, but ditching is required to enhance the operation of the pumps and to drain...
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Mining landscapes are avowedly complex and dynamic cultural resources, representing an important part of the nation's cultural heritage. They reflect changes in technology, social organization, and the influence of outside events. Mining landscapes are also representative of the experiences of change over time. This representative experience is not well-represented in the typical approach to considering preservation of mining districts during the review of federal projects. This thesis takes a different approach, developing a classification system with a greater focus on the changes that occur, and tests this against a small-scale lode mining district in Southcentral Alaska. While the ability to factor in change...
* We review the predicted changes in extreme events following climate change in flowing waters in arctic and subarctic regions. These regions are characterised by tundra or taiga ecosystems in either erosional or depositional glacial landforms or presently glacierised areas of the Northern Hemisphere. * The ecological and geomorphic effects of extreme meteorological and hydrological events, such as episodes of strongly increased precipitation, temperatures and flows, can be exacerbated by altered base conditions. For example, winter temperature variations between frost and thaw will become more frequent at many places because mean temperature during the winter is closer to 0 °C, potentially leading to changes in...
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1.?Mixed-wood boreal forests are often considered to undergo directional succession from shade-intolerant to shade-tolerant species. It is thus expected that overstorey gaps should lead to the recruitment of shade-tolerant conifers into the canopy in all stand development stages and that the recruitment of shade-intolerant hardwoods would be minimal except in the largest gaps. 2.?We analysed short-term gap dynamics over a large 6-km2 spatial area of mixed-wood boreal forest across a gradient of stands in different developmental stages with different times of origin since fire (expressed as stand ?age?) that were affected differentially by the last spruce budworm (SBW) outbreak. Structural measurements of the canopy...
The Yukon government’s proposal to build a large hydroelectric dam on one of Yukon’s large undammed rivers raises major environmental concerns, particularly about impacts on important fish populations. Hydroelectric dams have a well-documented history of disrupting and even destroying the ecology of rivers and lakes in northern Canada. Impacts on fish populations and their habitats have been widespread and often irreversible. The Yukon Government’s Next Generation Hydro initiative has identified ten potential sites for such a dam. In this report we summarize the major risks to fish and fish habitats of a new hydroelectric dam on a large river with the goal of providing Yukon communities and citizens with better...
The objective of this dissertation was to estimate the magnitude and mechanisms of lake area change in Alaskan National Wildlife Refuges. An efficient and objective approach to classifying lake area from Landsat imagery was developed, tested, and used to estimate lake area trends at multiple spatial and temporal scales for ∼23,000 lakes in ten study areas. Seven study areas had long-term declines in lake area and five study areas had recent declines. The mean rate of change across study areas was -1.07% per year for the long-term records and -0.80% per year for the recent records. The presence of net declines in lake area suggests that, while there was substantial among-lake heterogeneity in trends at scales of...
This thesis investigates snow-pack development and frost penetration in the Blackstone Uplands, Y.T. The purpose is to assess the use of an accessible reference site as an index of these conditions throughout the area. The project responds to local interest in improving management of snowmobile access to the region. Sixteen transects were monitored for snow depth in fall and winter 2006-07. Active-layer temperature was monitored by data logger during freeze-up. Below-normal snowfall permitted examination of snow-pack development with marginal conditions for snowmobile traffic. Prior to snow redistribution by wind, snow depth was controlled by elevation and the reference site had more snow than all valley-bottom...
PURPOSE: The exchange of lands between the U.S. Fish and Wildlife Service (FWS) and Doyon, Limited is proposed to enhance the Yukon Flats National Wildlife Refuge of Alaska. Since the refuge was established in 1980, Doyon has been interested in acquiring federal oil and gas interests in the south-central portion of dedicated area. Under the terms of an agreement in principle between the FWS and Doyon, the U.S. government would receive fee title to at least 150,000 acres of Doyon lands, including both surface and subsurface rights, with priority fish and wildlife habitats that can be incorporated into the refuge. Doyon would receive fee title to approximately 110,000 acres of refuge lands, including both surface...
The impact to the permafrost during and after wildfire was studied using 11 boreal forest fire sites including two controlled burns. Heat transfer by conduction to the permafrost was not significant during fire. Immediately following fire, ground thermal conductivity may increase 10-fold and the surface albedo can decrease by 50% depending on the extent of burning of the surficial organic soil. The thickness of the remaining organic layer strongly affects permafrost degradation and aggradation. If the organic layer thickness was not reduced during the burn, then the active layer (the layer of soil above permafrost that annually freezes and thaws) did not change after the burn in spite of the surface albedo decrease....
A large increase in Betula during a narrow 1000 year window, ~13,800 years before present (YBP) in Alaska and Yukon corresponded in time with the extinction of mammoths and the arrival of humans. Pollen data indicate the increase in Betula during this time was widespread across Siberia and Beringia. We hypothesize that Betula increased due to a combination of a warming climate and reduced herbivory following the extinction of the Pleistocene mega herbivores. The rapid increase in Betula modified land surface albedo which climate-model simulations indicate would cause an average net warming of ~0.021°C per percent increase in high latitude (5373°N) Betula cover. We hypothesize that the extinction of mammoths increased...
map background search result map search result map Use of military demolition explosives in a remediation project Eagle River Flats Remediation Project. Comprehensive Bibliography - 1950 to 1998 Interactions of multiple disturbances in shaping boreal forest dynamics: a spatially explicit analysis using multi-temporal lidar data and high-resolution imagery The mining landscape from a diachronic perspective: Examining the Kenai Star mining district, Southcentral Alaska Characteristics of sediment discharge in the subarctic Yukon River, Alaska Eagle River Flats pond pumping remediation project: fourth-year operations under the record of decision Biogeochemical pathways and land use associations of potentially toxic metals in the Anchorage watershed, Alaska Monitoring chloride migration from dust palliative applications on the Park road, Denali National Park and Preserve, Alaska: 2007 summary report Geometry of oriented lakes in Old Crow Flats, northern Yukon Biogeochemical pathways and land use associations of potentially toxic metals in the Anchorage watershed, Alaska Eagle River Flats Remediation Project. Comprehensive Bibliography - 1950 to 1998 Use of military demolition explosives in a remediation project Eagle River Flats pond pumping remediation project: fourth-year operations under the record of decision Geometry of oriented lakes in Old Crow Flats, northern Yukon Monitoring chloride migration from dust palliative applications on the Park road, Denali National Park and Preserve, Alaska: 2007 summary report Characteristics of sediment discharge in the subarctic Yukon River, Alaska Interactions of multiple disturbances in shaping boreal forest dynamics: a spatially explicit analysis using multi-temporal lidar data and high-resolution imagery