Geochemistry of the active layer and near-surface permafrost, Mackenzie delta region, Northwest Territories, Canada

2005 ◽  
Vol 42 (1) ◽  
pp. 37-48 ◽  
Author(s):  
S V Kokelj ◽  
C R Burn
Keyword(s):  
Northwest Territories ◽  
Active Layer ◽  
Permafrost Soil ◽  
Mackenzie Delta ◽  
Delta Region ◽  
Ion Content ◽  
Near Surface ◽  
Fine Grained ◽  
Permafrost Table ◽  
Soluble Ion

The soluble ion content of the active layer and near-surface permafrost was determined at 41 sites in the Mackenzie delta region, Northwest Territories, Canada. In delta soils, Ca2+ and Mg2+ are the dominant soluble cations, but the quantity and relative abundance of Na+ increase with proximity to the Beaufort Sea coast. Soils beneath frequently flooded surfaces are ion rich in comparison with ground above the level of decadal flooding. Within a terrain type, near-surface permafrost soil solute concentrations are similar between paired cores spaced <1 m apart, but at greater distances (cores spaced 3–13 m apart), solute concentrations are significantly different. Comparatively low soil solute concentrations in old upland surfaces near Inuvik may be a result of progressive removal of soluble materials from the active layer and permafrost during periods of deeper thaw. In sandy silt alluvium, solutes excluded during downward freezing may accumulate at the base of the active layer and be sequestered by a rising permafrost table. At sites with finer grained clayey silts, the correspondence between zones of ice and cation enrichment indicates coupled movement of water and solutes during freeze-back of the active layer and development of aggradational ice. Solute enrichment of near-surface permafrost is greatest at fine-grained ice-rich alluvial sites, where mean concentrations in permafrost are up to 7.5 times greater than those in the active layer.

Bottom-fast ice delineation with PolSAR and InSAR techniques in the Mackenzie Delta region, Northwest Territories, Canada

2013 ◽  
Vol 39 (4) ◽  
pp. 341-353 ◽  
Author(s):  
Bing Yue ◽  
Joseph Chamberland ◽  
John Mulvie
Keyword(s):  
Northwest Territories ◽  
Mackenzie Delta ◽  
Delta Region ◽  
Fast Ice

Near-surface ground ice in sediments of the Mackenzie Delta, Northwest Territories, Canada

2005 ◽  
Vol 16 (3) ◽  
pp. 291-303 ◽  
Author(s):  
S. V. Kokelj ◽  
C. R. Burn
Keyword(s):  
Northwest Territories ◽  
Mackenzie Delta ◽  
Ground Ice ◽  
Near Surface

Reindeer herding as private enterprise in Canada

Polar Record ◽  
1984 ◽  
Vol 22 (137) ◽  
pp. 127-136 ◽  
Author(s):  
J. K. Stager
Keyword(s):  
Northwest Territories ◽  
Private Enterprise ◽  
Private Ownership ◽  
Mackenzie Delta ◽  
Reindeer Herding ◽  
Delta Region ◽  
Management Decisions ◽  
Management Techniques ◽  
Government Management ◽  
Canadian Wildlife

AbstractAfter unsuccessful introductions of reindeer into Canada during the early decades of this century, a herd brought from Alaska in 1935 was maintained successfully under government management (latterly under the Canadian Wildlife Service) for almost 40 years in the Mackenzie Delta region, Northwest Territories. Sold in 1974 into private ownership, the herd has since increased substantially in size; new management techniques have been developed to herd, handle and slaughter the animals. Meat, antlers in velvet and skins are the main products of a small but profitable local industry under native ownership. Currently numbering some 16 000 animals, the herd now justifies new management decisions affecting its future size and the scope of the enterprise.

scholarly journals Grain-Scale Analysis of Solid-Phase Organic Matter and Arsenic Mobility in Mining-Impacted 1 Sediment from Sub‐Arctic Lakes, Northwest Territories, Canada

2021 ◽  
Author(s):  
Clare B Miller ◽  
Michael B Parsons ◽  
Heather E Jamieson ◽  
Omid H Ardakani ◽  
R Timothy Patterson ◽  
...  
Keyword(s):  
Organic Matter ◽  
Northwest Territories ◽  
Solid Phase ◽  
Arctic Lakes ◽  
Edge Structure ◽  
Near Surface ◽  
X Ray ◽  
Fine Grained ◽  
Arsenic Mobility ◽  
Co Precipitation

Abstract Arsenic (As) is commonly sequestered at the sediment-water interface (SWI) in mining-impacted lakes through adsorption and/or co-precipitation with authigenic iron (Fe)-(oxy)hydroxides or sulphides. The results of this study demonstrate that the accumulation of solid-phase organic matter (OM) in near-surface sediments also influences the mobility and fate of As in sub-Arctic lakes. Sediment gravity cores, sediment grab samples, and porewaters were collected from three lakes downstream of the former Tundra gold mine, Northwest Territories. Analysis of sediment using combined micro-X-ray fluorescence/diffraction, K-edge X-ray Absorption Near-Edge Structure (XANES), and organic petrography shows that As is associated with both aquatic (benthic and planktonic alginate) and terrestrially-derived OM (cutinite; funginite). Most As is hosted by fine-grained Fe-(oxy)hydroxides or sulphide minerals ( e.g., goethite, orpiment, lepidocrocite, mackinawite); however, grain-scale synchrotron-based analysis shows that As is also associated with amorphous OM. Mixed As oxidation states in porewater (median = 62 % As (V), 18 % As (III); n = 20) and sediment (median = 80 % As (-I) and (III), 19 % As (V); n = 9) indicate the presence of variable redox conditions in the near-surface sediment and suggest that post-depositional remobilization of As has occurred . Detailed characterization of As-bearing OM at and below the SWI suggests that OM plays an important role in stabilizing redox-sensitive authigenic minerals and associated As. Based on these findings, it is expected that increased concentrations of labile OM will drive post-depositional surface-enrichment of As in mining-impacted lakes and may increase or decrease As flux from sediments to overlying surface waters.

scholarly journals Vegetation of the Continental Northwest Territories at 6 ka BP

2007 ◽  
Vol 49 (1) ◽  
pp. 37-43 ◽  
Author(s):  
Glen M. MacDonald
Keyword(s):  
Northwest Territories ◽  
Populus Tremuloides ◽  
Picea Mariana ◽  
Picea Glauca ◽  
Pinus Banksiana ◽  
Arctic Tundra ◽  
Range Limits ◽  
Mackenzie Delta ◽  
Delta Region ◽  
Low Arctic

ABSTRACTPollen records are used to reconstruct vegetation in the continental Northwest Territories at 6 ka (6000 14C yr BP). Picea glauca, P mariana, Larix laricina, Populus tremuloides, P. balsamifera, Alnus crispa and A. incana were present throughout their modern ranges in the Boreal and Subarctic Forest Zones by 6000 BP. Pinus banksiana, however, had not yet reached its present northern limits. Population densities of the dominant trees, Picea glauca and Picea mariana, were close to, or as high as, present. In the Mackenzie Delta region the range limit of Picea glauca was approximately 25 km north of its modern location just prior to 6000 BP. In contrast, the northern limits of the forest in central Canada were similar to present. The tundra vegetation close to the edge of the forest was similar to modern Low Arctic Tundra. Development of extensive Sphagnum peatlands had begun in the forested areas and the adjacent Low Arctic Tundra. Palaeoecological information regarding vegetation at 6000 BP remains lacking for the northeastern half of the study area. Therefore, the nature of the vegetation in much of the area now occupied by Low Arctic and Middle Arctic Tundra remains unknown. Important vegetation changes that occurred following 6 ka include : (1) the advance of Pinus banksiana to its present northern range limits, (2) the retreat of the northern range limits of Picea glauca in the Mackenzie Delta region between 6000 and 3500 BP and (3) the rapid and marked increase in the population density of Picea mariana in the treeline zone of the central Northwest Territories at 5000 BP followed by a decline at 4000 BP.

Spatial Heterogeneity in the Shrub Tundra Ecotone in the Mackenzie Delta Region, Northwest Territories: Implications for Arctic Environmental Change

Ecosystems ◽  
2010 ◽  
Vol 13 (2) ◽  
pp. 194-204 ◽  
Author(s):  
Trevor C. Lantz ◽  
Sarah E. Gergel ◽  
Steven V. Kokelj
Keyword(s):  
Environmental Change ◽  
Spatial Heterogeneity ◽  
Northwest Territories ◽  
Mackenzie Delta ◽  
Delta Region ◽  
Shrub Tundra

The origin of hummocks, western Arctic coast, Canada

1980 ◽  
Vol 17 (8) ◽  
pp. 996-1006 ◽  
Author(s):  
J. Ross Mackay
Keyword(s):  
Northwest Territories ◽  
Active Layer ◽  
Late Summer ◽  
Field Observations ◽  
Soil Pressure ◽  
Freeze Thaw ◽  
Fine Grained ◽  
Field Evidence ◽  
Upward Displacement ◽  
Upward Moving

Hummocks (nonsorted circles) are widely distributed in arctic and subarctic regions. The hummocks under discussion are composed of fine-grained frost-susceptible soils; the late summer frost table is bowl-shaped; and the hummocks grade from those which are completely vegetated (earth hummocks) to those with bare centres (mud hummocks). The mound form is usually attributed to an upward displacement of material resulting from cryostatic (freeze-back) pressure generated in a confined, wet, unfrozen pocket of the active layer. Theoretically, cryostatic pressure should not develop in a frost-susceptible hummock soil, because ice lensing at the top and (or) bottom of the active layer will desiccate the last unfrozen pocket so that the pore water is under tension, not pressure. Field observations carried out at Garry Island, Northwest Territories, for 1965–1979 and for 1967–1979 at Inuvik, Northwest Territories, involving: summer and winter excavations; the measurement of the deformation of tubes, soil pressure, soil temperature, soil heave, soil moisture migration; and observations on hummock stability provide no field evidence for the cryostatic theory. An alternative model of hummock growth, based upon field observations, is here proposed. The upward displacement of material is believed caused by freeze–thaw of ice lenses at the top and bottom of the active layer with a gravity-induced cell-like movement, because the top and bottom freeze–thaw zones have opposite curvatures. The cell circulation is evident from the grain-size distribution of hummock soils and from upward-moving tongues of saturated soil observable in late summer. The most active period is in late summer. Model experiments in the laboratory have been successful in producing mounds by freeze–thaw of a kaolin slurry in a bowl-shaped container in support of the proposed theory.

Sign in / Sign up

Export Citation Format

Share Document