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A systematic water-quality study of the Fortymile River and many of its major tributaries in eastern Alaska was conducted in June of 1997 and 1998. Surface-water samples were collected for chemical analyses to establish regional baseline geochemistry values and to evaluate the possible environmental effects of suction-dredge placer gold mining and bulldozer-operated placer gold mining (commonly referred to as “cat mining”). In general, the water quality of the Fortymile River is very good, with low total dissolved solids and only two cases in which the concentration of any element exceeded primary or secondary drinking-water quality standards. In both cases, iron exceeded secondary drinking-water limits. At...
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Daily records of the location and timing of human- and lightning-caused fires in British Columbia from 1981 to 2000 were used to estimate the probability of fire occurrence within 950 20 × 20-km spatial units (~950 000 km2) using a binary logistic regression modelling framework. Explanatory variables included lightning strikes, forest cover, surface weather observations, atmospheric stability indices and fuel moisture codes of the Canadian Fire Weather Index System. Because the influence of the explanatory variables in the models varied from year to year, model coefficients were estimated for each year. The arithmetic mean of the model coefficients was used for making daily predictions in a future year. A confidence...
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We present the Berkeley-Trent North American contaminant fate model (BETR North America), a regionally segmented multimedia contaminant fate model based on the fugacity concept. The model is built on a framework that links contaminant fare models of individual regions, and is generally applicable to large, spatially heterogeneous areas. The North American environment is modeled as 24 ecological regions, within each region contaminant fate is described using a 7 compartment multimedia fugacity model including a vertically segmented atmosphere, freshwater, freshwater sediment, soil, coastal water and vegetation compartments. Inter-regional transport of contaminants in the atmosphere, freshwater and coastal water is...
The term ?invader? is typically paired with adjectives such as ?non-native? and ?alien?, yet native species can also cause ecological and economic impacts that rival those of well-known invasive species. By spreading within their historical range, attaining extreme abundances, and exerting severe per-capita effects as a result of predation or competition, native invaders can create an unusual set of challenges for science, management, policy, and society. Identifying when, where, and why species become invaders in their native ranges requires additional scientific inquiry, outside the current focus of invasion biology. Management strategies often mitigate the symptoms rather than address the causes of problematic...
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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...
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"Stratospheric ozone is of crucial importance for life on Earth. This thin layer protects us from the ultraviolet solar radiation and also works as a greenhouse gas that helps maintain our climate. Large changes in thickness and vertical distribution of the ozone abundance may have detrimental effects on life on Earth. But even small changes could have considerable impact on UV irradiance, bio-production and cancer rates. During the last decade record low spring time vertical column amounts of stratospheric ozone have been observed over Northern Europe. However, this decrease is not as severe as the depletion observed over Antarctica and at mid-latitudes in the Southern Hemisphere. The discovery of the spring time...
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Yukon River Watershed Alaska; This modified version of the DEC's July, 2002 Contaminated Sites Database (BP_qryFOIA.txt) has had non-Yukon River Watershed sites removed and is available as an Excel file from the YRITWC office. The database itself (which does not include information on underground storage tanks or leaking underground storage tanks; see "DEC, 2002. Alaska Underground Storage Tank: UST and LUST Search.") is generated monthly by the DEC and can be requested from their Contaminated Sites Program, Spill Prevention and Response Division Anchorage Office at (907)269-7558. This version contains reference to over 700 documented waste sites in the Yukon Watershed, reporting a variety of waste types - from...
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Contrary to stereotypes of proto-Athapaskan culture as simplistic and archaic, evidence points to a sophisticated web of late prehistoric Asian-Athapaskan interactions. A holistic assessment of Athapaskan migrations in the context of the transpacific Dene-Yeneseian phylum (the largest, fastest pedestrian language spread on earth) sees Athapaskan-Asian connections (in language, technology, DNA, social organization, etc.) as reflecting profound large-scale cultural-historical processes whose implications have yet to be grasped. Current understanding is that Athapaskans slowly migrated south in response to volcanic eruptions in southwest Yukon Territory after circa 200 and 800 CE. Yet problems remain, notably the archaeological...


    map background search result map search result map Experimental and theoretical investigation of stratospheric ozone depletion in the northern hemisphere caused by heterogeneous chemistry Prediction of daily lightning- and human-caused fires in British Columbia Material cultural correlates of the Athapaskan expansion: A cross-disciplinary approach Regional baseline geochemistry and environmental effects of gold placer mining operations on the Fortymile River, eastern Alaska Carbon dioxide and methane emissions from the Yukon River system BETR North America: A regionally segmented multimedia contaminant fate model for North America Assessing forest intactness in the boreal forest of Canda: a reiew of existing global anbd regional maps. Draft A refinement of models projecting future Canadian fire regimes using homogeneous fire regime zones Large-Scale Geospatial Mapping of Forest Carbon Dynamics Using Landsat TM data to estimate carbon release from burned biomass in an Alaskan spruce forest complex Spatial scale-dependent land-atmospheric methane exchange in the northern high latitudes from 1993 to 2004 A Burning Interest in Boreal Forests: Researchers in Alaska Link Fires with Climate Change Experimental and theoretical investigation of stratospheric ozone depletion in the northern hemisphere caused by heterogeneous chemistry Regional baseline geochemistry and environmental effects of gold placer mining operations on the Fortymile River, eastern Alaska Large-Scale Geospatial Mapping of Forest Carbon Dynamics Using Landsat TM data to estimate carbon release from burned biomass in an Alaskan spruce forest complex A Burning Interest in Boreal Forests: Researchers in Alaska Link Fires with Climate Change Assessing forest intactness in the boreal forest of Canda: a reiew of existing global anbd regional maps. Draft Prediction of daily lightning- and human-caused fires in British Columbia Carbon dioxide and methane emissions from the Yukon River system Material cultural correlates of the Athapaskan expansion: A cross-disciplinary approach Spatial scale-dependent land-atmospheric methane exchange in the northern high latitudes from 1993 to 2004 A refinement of models projecting future Canadian fire regimes using homogeneous fire regime zones BETR North America: A regionally segmented multimedia contaminant fate model for North America