Mackenzie River Valley Research Articles

Recent peat and carbon accumulation on changing permafrost landforms along the Mackenzie River valley, Northwest Territories, Canada

Northwestern Canada is currently warming nearly four times faster than the global average, driving accelerated permafrost thaw and changes to ecosystem vegetation, hydrology and landscape structure across the landscape. While permafrost peatlands constitute a large carbon reservoir, there is no consensus yet on the direction and magnitude of changes to their vulnerable carbon balance. Here, we assessed changes in peatland ecosystems following permafrost thaw at three sites located along a 1000 km long climate and permafrost gradient along the Mackenzie River valley, Canada. Specifically, we examined vegetation succession over the last few decades to evaluate the possible impact of climate warming on peat and carbon accumulation. Results from the palaeoecological analysis of 20 surficial peat cores, supported by robust chronologies, show a return to Sphagnum accumulation since ca. 1980 CE in the sporadic and discontinuous permafrost zones and ca. 2000 CE in the continuous permafrost zone. The average rates of peat and carbon accumulation reached 4 mm yr−1 and 134 g C m−2 yr−1 at the northernmost site in the continuous permafrost zone. In contrast, peat and carbon accumulation reached 3 mm yr−1 and 81 g C m−2 yr−1, respectively, in the sporadic and discontinuous permafrost zones. This study highlights the need for a net carbon budget that integrates the recent accelerated Sphagnum growth and carbon uptake from the atmosphere to better assess the potential carbon emissions offset following permafrost thaw. High-resolution palaeoecological studies can offer insights into decadal-scale patterns of vegetation and carbon balance changes to improve model predictions of peat climate-carbon cycle feedbacks.

On the configuration and initialization of a large-scale hydrological land surface model to represent permafrost

Abstract. Permafrost is an important feature of cold-region hydrology, particularly in river basins such as the Mackenzie River basin (MRB), and it needs to be properly represented in hydrological and land surface models (H-LSMs) built into existing Earth system models (ESMs), especially under the unprecedented climate warming trends that have been observed. Higher rates of warming have been reported in high latitudes compared to the global average, resulting in permafrost thaw with wide-ranging implications for hydrology and feedbacks to climate. The current generation of H-LSMs is being improved to simulate permafrost dynamics by allowing deep soil profiles and incorporating organic soils explicitly. Deeper soil profiles have larger hydraulic and thermal memories that require more effort to initialize. This study aims to devise a robust, yet computationally efficient, initialization and parameterization approach applicable to regions where data are scarce and simulations typically require large computational resources. The study further demonstrates an upscaling approach to inform large-scale ESM simulations based on the insights gained by modelling at small scales. We used permafrost observations from three sites along the Mackenzie River valley spanning different permafrost classes to test the validity of the approach. Results show generally good performance in reproducing present-climate permafrost properties at the three sites. The results also emphasize the sensitivity of the simulations to the soil layering scheme used, the depth to bedrock, and the organic soil properties.

Permafrost thaw and implications for the fate and transport of tritium in the Canadian north

Layers of permafrost developed during the 1950s and 1960s incorporated tritium from the atmosphere that originated from global nuclear weapons testing. In regions underlain by substantial permafrost, this tritium has been effectively trapped in ice since it was deposited and subject to radioactive decay alone, which has substantially lengthened its environmental half-life compared to areas with little or no permafrost where the weapons-test era precipitation has been subject to both decay and hydrodynamic dispersion. The Arctic is warming three times faster than other parts of the world, with northern regions incurring some of the most pronounced effects of climate change, resulting in permafrost degradation. A series of 23 waterbodies across the Canadian sub-Arctic spanning the continuous, discontinuous and isolated patches permafrost zones in northern Manitoba, Northwest Territories and Labrador were sampled. Surface water and groundwater seepage samples were collected from each lake and analyzed for tritium, stable isotopes (δ18O and δ2H) and general water chemistry characteristics. Measured tritium was significantly higher in surface waters (SW) and groundwater seepage (GW) in water bodies located in the sporadic discontinuous (64 ± 15 T U. in SW and 52 ± 9 T U. in GW) and extensive discontinuous (53 ± 7 T U. in SW and 61 ± 7 T U. in GW) permafrost regions of the Northwest Territories than in regions underlain by continuous permafrost in northern Manitoba (<12 T U. in both SW and GW) or those within isolated patches of permafrost in Labrador (16 ± 2 T U. in SW and 21 ± 4 T U. in GW). The greatest tritium enrichment (up to 128 T U.) was observed in lakes near Jean Marie River in the Mackenzie River valley, a region known to be experiencing extensive permafrost degradation. These results demonstrate significant permafrost degradation in the central Mackenzie River basin and show that tritium is becoming increasingly mobile in the sub-Arctic environment—at concentrations higher than expected—as a result of a warming climate. A better understanding of the cycling of tritium in the environment will improve our understanding of Arctic radioecology under changing environmental conditions.

The multi-phase Keele Arch, central Mackenzie Corridor, Northwest Territories

Abstract Keele Arch is a zone of anomalous structural, erosional, and depositional features along a corridor east of the Colville Hills and the northern Franklin Mountains, Northwest Territories, a region with significant economic potential. First described in 1975, it has since been found to have had a long history of uplift-to-sag reversals. This report presents a series of maps and sections, based largely on flattened reflection seismic lines that illustrate key stages of the arch’s development through time and space. In doing so it lays the foundation for future assessments of the arch’s influence on the surrounding stratigraphy. Preceded by a late Proterozoic syncline, it evolved through five major stages: 1) subsidence into a chain of Cambrian to mid-Ordovician grabens; 2) uplift of its central and southern zones to form a Late Silurian (pre-Devonian) arch; 3) renewed uplift into a pre-Cretaceous arch between the region east the Colville Hills and the Mackenzie River valley near Johnson River; 4) mid-Cretaceous reactivation of the pre-Cretaceous and southern pre-Devonian arches; and 5) subsidence of its central zone into Brackett Basin during the late-Campanian to Paleocene and inversion of the Cambrian McConnell Graben into the McConnell Range during late-Campanian to Paleocene time. The feature can be divided into four parts: 1) A northern segment between the Northern Franklin Mountains and the region east of the Colville Hills; 2) The north half of its central zone, where Cambro-Ordovician strata are exposed east of the northern Franklin Mountains; 3) The southern portion of the central zone between Brackett Lake and Keele River, where Tertiary rocks lie at the surface. This is the best documented and most tectonically active segment; and 4) a poorly understood segment under Mackenzie Valley, south of Keele River.

Landry Formation of Kugaluk N-02 well (Devonian, northern mainland NWT): insight into formation's boundaries, lithofacies, and stratal stacking patterns

Abstract The CPOG Kugaluk N-02 well drilled east of Inuvik (the northern Mackenzie River valley) preserves an essentially complete stratigraphic record of the Devonian Landry Formation. Detailed examination of the core demonstrates that the contact between the Landry Formation and the overlying Headless Formation is gradational and conformable, recording upward deepening. The Landry Formation is 216 m thick and composed of characteristic metre-scale peritidal T-R sequences. The highstand end of the facies spectrum is composed of shallow-subtidal fossiliferous packstones, grainstones, and minor tabulate-coral boundstones. The shallowest marine parts of sequences are notably thick (30% of the total succession) and represented by laminated tidal-flat calcimudstones, calcisiltites, and birds-eye dismicrites with occasional supratidal brecciation. Rooted and synsedimentary pedogenized palustrine calcimudstones are recognized in initial-transgressive parts of sequences. The sequences are bounded by disconformities with paleokarst profiles of different depths and degree of host-rock weathering. The log combining lithofacies and subaerial exposure profiles reveals hierarchical 4th to 5th order cyclicity with inferred amplitudes of sea-level fluctuations ranging between 10 and 20 metres. This high-frequency cyclicity may have glacioeustatic origin, which is consistent with the relatively cool (22°C in average) surface tropical waters of the late Emsian–Givetian Ocean. The base of the Landry Formation is gradational and spatially diachronous, defined by a downward increase in dolomite content and limestone-dolostone interbedding. A thick paleosol near the base of Landy Formation may have potential for regional allostratigraphic correlations.

A late Pleistocene steppe bison ( Bison priscus) partial carcass from Tsiigehtchic, Northwest Territories, Canada

A partial steppe bison ( Bison priscus) carcass was recovered at Tsiigehtchic, near the confluence of the Arctic Red and Mackenzie Rivers, Northwest Territories, Canada in September of 2007. The carcass includes a complete cranium with horn cores and sheaths, several complete post-cranial elements (many of which have some mummified soft tissue), intestines and a large piece of hide. A piece of metacarpal bone was subsampled and yielded an AMS radiocarbon age of 11,830 ± 45 14C yr BP (OxA-18549). Mitochondrial DNA sequenced from a hair sample confirms that Tsiigehtchic steppe bison ( Bison priscus) did not belong to the lineage that eventually gave rise to modern bison ( Bison bison). This is the first radiocarbon dated Bison priscus in the Mackenzie River valley, and to our knowledge, the first reported Pleistocene mammal soft tissue remains from the glaciated regions of northern Canada. Investigation of the recovery site indicates that the steppe bison was released from the permafrost during a landslide within unconsolidated glacial outwash gravel. These data indicate that the lower Mackenzie River valley was ice free and inhabited by steppe bison by ∼11,800 14C years ago. This date is important for the deglacial chronology of the Laurentide Ice Sheet and the opening of the northern portal to the Ice Free Corridor. The presence of steppe bison raises further potential for the discovery of more late Pleistocene fauna, and possibly archaeological evidence, in the region.

The Role of Northern Lakes in a Regional Energy Balance

Abstract There are many lakes of widely varying morphometry in northern latitudes. For this study region, in the central Mackenzie River valley of western Canada, lakes make up 37% of the landscape. The nonlake components of the landscape are divided into uplands (55%) and wetlands (8%). With such abundance, lakes are important features that can influence the regional climate. This paper examines the role of lakes in the regional surface energy and water balance and evaluates the links to the frequency–size distribution of lakes. The primary purpose is to examine how the surface energy balance may influence regional climate and weather. Lakes are characterized by both the magnitude and temporal behavior of their surface energy balances during the ice-free period. The impacts of combinations of various-size lakes and land–lake distributions on regional energy balances and evaporation cycles are presented. Net radiation is substantially greater over all water-dominated surfaces compared with uplands. The seasonal heat storage increases with lake size. Medium and large lakes are slow to warm in summer. Their large cumulative heat storage, near summer’s end, fuels large convective heat fluxes in fall and early winter. The evaporation season for upland, wetland, and small, medium, and large lakes lasts for 19, 21, 22, 24, and 30 weeks, respectively. The regional effects of combinations of surface types are derived. The region is initially treated as comprising uplands only. The influences of wetland, small, medium, and large lakes are added sequentially, to build up to the energy budget of the actual landscape. The addition of lakes increases the regional net radiation, the maximum regional subsurface heat storage, and evaporation substantially. Evaporation decreases slightly in the first half of the season but experiences a large enhancement in the second half. The sensible heat flux is reduced substantially in the first half of the season, but changes little in the second half. For energy budget modeling the representation of lake size is important. Net radiation is fairly independent of size. An equal area of medium and large lakes, compared with small lakes, yields substantially larger latent heat fluxes and lesser sensible heat fluxes. Lake size also creates large differences in regional flux magnitudes, especially in the spring and fall periods.

Sources and Significance of Alkane and PAH Hydrocarbons in Canadian Arctic Rivers

Hydrocarbon measurements have been made on dissolved, suspended particulate and sediment samples collected in 1987, 1993 and 1994 from the Mackenzie River delta and shelf and in 1993 from 10 smaller Northwest Territories and Nunavut rivers that drain into the Canadian Archipelago or Hudson's Bay. Suspended particulate samples from all rivers have a resolved higher alkane pattern with a well-defined odd–even predominance consistent with a major source in terrestrial, vascular plant material. Particulate samples from the 10 smaller rivers have alkane concentrations that are similar to the Mackenzie River during summer, but PAH (polycyclic aromatic hydrocarbon) concentrations are approximately 10 times lower for the parent PAHs and 100 times lower for alkyl PAHs. PAHs on suspended particulate from the Mackenzie River exhibit a uniform composition typical of mature petrogenic sources, while PAHs in the smaller rivers are typical of combustion. The virtual absence of petrogenic PAHs in the smaller rivers is the single most important difference between these and the Mackenzie River. During summer the alkane and PAH composition of suspended particulate in the Mackenzie River is sufficiently homogenous to estimate directly the hydrocarbon load from the particulate load. Mackenzie River particulates and sediments have the hopane and sterane ratios characteristic of immature bitumens, shales or coals from the Devonian Canol formation that outcrops in the lower Mackenzie River valley. The erosion of organic-rich rocks from this formation is likely the source of the refractory petrogenic material found in the Mackenzie River delta and shelf. Data are insufficient to determine whether the petrogenic lower alkanes and PAHs have the same source or whether more mature petroleum also contributes. Because sediment samples (suspended and bed) from the Mackenzie delta have natural PAH concentrations that exceed the level where adverse biological effects are expected to occur, there is an urgent need to establish whether these petroleum-derived PAHs are bioavailable and if they are inducing effects in bottom fish and other biota.

Range Extension of Bull Trout, &lt;i&gt;Salvelinus confluentus&lt;/i&gt;, to the Central Northwest Territories, with Notes on Identification and Distribution of Dolly Varden, &lt;i&gt;Salvelinus malma&lt;/i&gt;, in the Western Canadian Arctic

The presence of bull trout ( Salvelinus confluentus ) is reported from four locations in the Sahtu Settlement Area of the Northwest Territories centered about 64°30'N and 125°00'W. These reports extend the geographical range of this species approximately 500 km north of the previous northernmost published localities in the southern Northwest Territories (~61°N, 125°W, Prairie Creek, Liard River drainage). The identity of these char is confirmed using quantitative criteria in a linear discriminant function from the literature shown to be 100% effective in distinguishing bull trout from Dolly Varden ( S. malma ). Regular captures of these fish at one location over several years indicate that these records likely represent established populations and not extralimital occurrences. We hypothesize that bull trout are more extensively distributed in high-gradient streams and rivers of the south-central Mackenzie River valley and likely also occur north of this area. Only limited scientific work has been done in the area, and data on taxonomy and distributions of species are generally lacking. In much of the previous literature, reports of char (other than lake trout, S . namaycush ) have identified the fish as Dolly Varden or arctic char ( S. alpinus ). These identifications are suspect, and care must be taken when interpreting such literature. The presence and vulnerability of bull trout present significant challenges for their conservation and management in this area.

Seasonal patterns of coupled flow in the active layer at three sites in northwest North America

Vertical arrays of temperature and electric-potential probes were installed in the upper soil at sites along the Mackenzie River valley and on the North Slope of Alaska. Time series were obtained at subdiurnal frequencies throughout the year in the active layer and upper permafrost. If the data acquisition system is properly configured, the time series can be used to infer soil physiochemical processes. The electric potential develops primarily in response to soil water solute concentration gradients in the soil column, and is a crude surrogate of the soil water electrolytic conductivity. Summer precipitation can cause rapid penetration of the thaw front when percolating rainwater, warmed at the ground surface, carries sensible heat downward to the thawing front. Rates of warming at depth occur significantly faster than those typical of conductive heat transfer. In early winter, as the freezing front penetrates downward toward the permafrost table, ions are excluded from the ice and concentrated in the intermediate unfrozen zone. Nearly instantaneous warming of the active layer is triggered by spring snowmelt. At Happy Valley in northern Alaska, temperatures at the 29 cm depth rise from −7 to −3 °C in 1 h. For several hours during this event, the temperature at 29 cm is warmer than that at regions both above and below, producing a strong thermal inversion. Time series of electric potential, or a surrogate derived from electric potential, suggest rapid transport of meltwater from the snowpack to depth, probably through soil cracks. Serial events hasten active-layer warming by 1–2 weeks.

The influence of clay-sized particles on seismic velocity for Canadian Arctic permafrost

Seismic-wave velocities have been measured on 37 unconsolidated permafrost samples as a function of temperature in the range -16 to +5 °C. The samples, taken from a number of locations in the Canadian Arctic islands, the Beaufort Sea, and the Mackenzie River valley, were tighty sealed immediately upon recovery in several layers of polyethylene film and maintained in their frozen state during storage, specimen preparation, and until they were tested under controlled environmental conditions. During testing, the specimens were subjected to a constant hydrostatic confining stress of 0.35 MPa (50 psi) under drained conditions. At no stage was a deviatoric stress applied to the permafrost specimens. The fraction of clay-sized particles in the test specimens varied from almost zero to approximately 65%. At temperatures below -2 °C the compressional-wave velocity was observed to be a strong function of the fraction of clay-sized particles, but only a weak function of porosity. At temperatures above 0 °C the compressional-wave velocity was observed to be a function only of porosity, with virtually no dependence upon the fraction of clay-sized particles. Calculation of the fractional ice content of the permafrost pore space from the Kuster and Toksöz theory showed that for a given fraction of clay-sized particles the ice content increases with an increase in porosity. It is concluded that the compressional-wave velocity for unconsolidated permafrost from the Canadian Arctic is a function of the water-filled porosity, irrespective of the original porosity, clay content, or temperature.

The enemy of every tribe: “bushman” images in Northern Athapaskan narratives

A variety of “bushman” images are found throughout the Northern Athapaskan area. They have been typically characterized as supernatural beliefs arising in response to fears of dangers in the natural and social environments and to ignorance of true causes of events. I argue in this paper that an understanding of the images must also take into account the cultural and social systems that govern their creation and use in personal narratives. In particular, the images within one region, the central Mackenzie River valley, must be understood in terms of the focal concerns of seasonality, supernatural power, social relationships, and technology, as well as the explanatory uses to which the narratives are put.

Landscape Mapping in the Mackenzie River Valley

Terrain over a wide area of the Mackenzie River valley was evaluated on the basis of vegetation-landform patterns, identifiable in air photographs as landscape units, which could be grouped into regions with climatic connotations. From a ground inspection of selected sites, it was shown that each landscape unit comprised a complex of elements characterized by permafrost relationships. An evaluation of the terrain over a much wider area was extrapolated from the air photographs. Vegetation or landform alone did not permit of a satisfactory delineation of regions with climatic connotations, since they were both so diffusely distributed.

A Landscape Zonation for the Southern and Central Mackenzie River Valley based on Terrain Permafrost Characteristics

A landscape zonation is presented for the southern and central Mackenzie River valley, based on observed changes in permafrost characteristics of selected terrain types, with changing climatic implications. The relative abundance of lichen on specified terrain types suggests the thickness of the active layer within the discontinuous permafrost zone, and is a useful guide in air photograph interpretation for extensive mapping of landscape–permafrost realtionships between localities of ground inspection. Widespread, fossil, cryoturbated terrain supports the contention that today's climate in the study area is less severe than that in the past.

The Distribution and possible Genesis of some Organic Terrain Patterns in the Southern Mackenzie River Valley

Terrain types in the southern Mackenzie River valley can be arranged into morphological series which are, in part, continuous and, in part, discontinuous, so as to allow speculation on the probable evolution of organic terrain in the area from frozen to unfrozen landscapes, accompanying the long-term amelioration of the climate during postglacial times. Stipploid terrain on gentle slopes retained its lineated character during progressive thawing. Similarly, polygoid terrain on frozen flats retained its reticulate character, though progressive thawing locally was probably associated with increasingly diffuse pattern boundaries, ultimately yielding marbloid organic terrain. Some frozen terrazoid terrain of raised peat probably evolved into unfrozen polygoid peatland by a progressive enlargement of water-filled depressions.

Succession in Unburned Subarctic Woodlands

A preliminary comparison of burned and unburned tracts in the northern boreal forest of the lower Mackenzie River valley indicates that, without periodic fires, trees will be eliminated and the climax vegetation will be a moss/lichen association. The implications for land management are adumbrated.

Middle and Upper Devonian Biostratigraphy in Canadian Northwest Territories: ABSTRACT

Middle and early Late Devonian rocks are well exposed End_Page 2473------------------------------ in the Mackenzie River drainage basin, particularly on the shores of Great Slave Lake and in the Franklin and Mackenzie Mountains. The biostratigraphy of these rocks can be considered in terms of 3 sequences characteristic of 3 adjacent regions--those of Great Slave Lake, upper Mackenzie River valley, and lower Mackenzie River valley--each of which contains several richly fossiliferous formations. During the last 20 years, demand for progressively more refined biostratigraphy has followed in the wake of regional mapping and increasingly detailed lithostratigraphy. In 1956, Warren and Stelck established the framework for a series of widely recognized zones. Subsequently, many faunal elements were described in detail, most notably by Crickmay, which led inevitably to modification and restriction of Warren and Stelck's framework. Most recently, attention has been focused on individual groups to obtain more precise information on stratigraphic ranges. McLaren's study in 1963 of rhynchonelloids serves as an outstanding example of such a contribution and, although details are as yet unpublished, smooth spiriferoids, long recognized as valuable stratigraphic indicators in Nevada, can e shown to hold comparable potential to the rhynchonelloids. Likewise, Braun's studies of ostracods in 1966-1967 have stressed a group that has the added advantage of equal application to both outcrop and subsurface section. The faunas of northern Canada support the thesis of waning provincialism and dominance by Old World faunas in Givetian and Frasnian times. Such groups as digonophyllid tetracorals and the oft-disregarded schizophoriid brachiopods demonstrate the Old World influence. End_of_Article - Last_Page 2474------------

John Aito Pihlainen (1926-1964)

John Aito Pihlainen, civil engineer and a Fellow of the Arctic Institute since 1960, died suddenly in Ottawa in January of this year. He was born in Finland and emigrated to Canada with his parents in 1928. In 1950 he obtained his B.Eng. degree at McGill University and his M.Sc. at Purdue University two years later. He joined the Division of Building Research of the National Research Council in 1950 and pioneered the Division's investigations of permafrost and associated construction problems in northern Canada, beginning with a survey in 1950 of the construction and performance of buildings in the Mackenzie River valley. The following year he worked again in the Mackenzie Valley with an expedition examining the applicability of air photo interpretation methods for engineering site surveys in permafrost areas. In 1952 he established the Division's Northern Research Station at Norman Wells, N.W.T. from which numerous permafrost field projects were carried out in the Mackenzie Valley over a number of years. The Aklavik Relocation Survey of 1954 took him and his colleagues to the Mackenzie Delta where he was in charge of permafrost investigations to select a new townsite. For the next few years he was closely associated with the varied and comprehensive permafrost engineering studies being carried out by the Division of Building Research at Inuvik using this new town as a field laboratory. He also carried out field investigations in other parts of Canada's permafrost region and during his ten years with the National Research Council he became widely known for his broad knowledge of permafrost and associated engineering problems, and development of the philosophy of carefully executed site investigations prior to construction. In December 1960 he left the National Research Council and entered into private practice as an arctic consulting engineer based in Ottawa. During the three years prior to his death he was engaged in various engineering projects throughout northern Canada. Through his field work and many published papers he made notable contributions to the advancement of engineering site investigations and construction in permafrost areas. John Pihlainen was universally liked and respected for his practical approach mixed with an unusual sense of good humour. By many people living in the North, he was affectionately known as Johnny Permafrost. His unexpected and tragic death cut short a successful career which had promised to add many more notable contributions to the development of Canada's permafrost region.

Notes on Devonian faunas of the MacKenzie River valley

Notes on Devonian faunas of the MacKenzie River valley