Destruction of ecosystems and infrastructure can be caused by melting of massive ice within permafrost. To predict potential melting caused by natural and human disturbance, we need to know the nature and origin of massive ice deposits. The purpose of this research was to evaluate the nature of massive ice in coarse-grained sediments that accepted theories suggest should not occur. / Degradation of ice-rich granular resources is expensive and difficult to rehabilitate and can cause developmental thermokarst, overestimation of granular resources, disturbance of wildlife habitat and create conflicts with traditional land uses. / To locate massive ice we used a resistivity geophysical technique and to characterize the ice we used geochemical, petrographic and stratigraphic techniques. The resistivity technique detected bodies of massive ice and ice-rich sediments and coarse-grained sediments at high resolutions and laboratory analysis reveal that the ice was of glacial origin. / These findings indicate that massive ice of glacial origin occurs in coarse-grained sediments in permafrost. The techniques used in this study could form the basis of a predictive model of massive ice occurrence.

No description available.

Winter roads, built from compacted snow and I or ice, are common throughout the circumpolar North. They are considered effective and economical means of providing seasonal access into permafrost terrain while minimizing the potential for environmental damage. The purpose of this study is an appraisal of long-term environmental impacts of winter roads by comparative assessment of terrain morphology, microclimate, permafrost, soils, and vegetation, on winter road right-of-ways and in adjacent undisturbed control areas.

Mercury (Hg) is a known neurotoxin that is often found in concentrations exceeding safe consumption guidelines in aquatic biota. This is evident in northern Canada, where northerners consume significant amounts of animals such as beluga, seals and burbot. In the Mackenzie River Basin, recent increases in Hg concentration in many of these animals over the past 25 years have been observed. The warming climate, and with it, the changing carbon cycle, are hypothesised in this thesis to play a role in the increases. Within the context of the two major zones (mountainous and peatland), with distinct geomorphology, hydrology and geology, traditional fossil fuel exploration methods (Rock-Eval pyrolysis, organic petrography) have been employed in a novel manner on recent sediments to qualify and quantify the OM and several geochemical analyses have been used to determine the geochemical sources of Hg. The mountainous zone is composed mostly of refractory OM, from forest fire char and heavily reworked OM. It also contains, and fluxes, most of the Hg, which derives from oxidative weathering and erosion of widespread sulfide minerals. However, Hg from this zone is in chemical forms of limited bioavailability. The peatland zone has a greater proportion of labile OM, with higher concentrations of DOC and algal-derived OM. Lake-fed tributaries in this zone contain even higher proportions of labile OM. At one of these sites, the sediment core record shows that Hg has been increasingly associated with labile OM over time, due to increasing primary productivity accelerated by climate change, and is resulting in an increase in scavenged Hg. The temporal trend in algal-bound Hg in the sediment record matches very well with the temporal trend of Hg in burbot sampled from the area, providing one of the first and strongest lines of evidence for the climatic impact on Hg bioaccumulation in Arctic ecosystems.

Mercury (Hg) is a known neurotoxin that is often found in concentrations exceeding safe consumption guidelines in aquatic biota. This is evident in northern Canada, where northerners consume significant amounts of animals such as beluga, seals and burbot. In the Mackenzie River Basin, recent increases in Hg concentration in many of these animals over the past 25 years have been observed. The warming climate, and with it, the changing carbon cycle, are hypothesised in this thesis to play a role in the increases. Within the context of the two major zones (mountainous and peatland), with distinct geomorphology, hydrology and geology, traditional fossil fuel exploration methods (Rock-Eval pyrolysis, organic petrography) have been employed in a novel manner on recent sediments to qualify and quantify the OM and several geochemical analyses have been used to determine the geochemical sources of Hg. The mountainous zone is composed mostly of refractory OM, from forest fire char and heavily reworked OM. It also contains, and fluxes, most of the Hg, which derives from oxidative weathering and erosion of widespread sulfide minerals. However, Hg from this zone is in chemical forms of limited bioavailability. The peatland zone has a greater proportion of labile OM, with higher concentrations of DOC and algal-derived OM. Lake-fed tributaries in this zone contain even higher proportions of labile OM. At one of these sites, the sediment core record shows that Hg has been increasingly associated with labile OM over time, due to increasing primary productivity accelerated by climate change, and is resulting in an increase in scavenged Hg. The temporal trend in algal-bound Hg in the sediment record matches very well with the temporal trend of Hg in burbot sampled from the area, providing one of the first and strongest lines of evidence for the climatic impact on Hg bioaccumulation in Arctic ecosystems.

<p> The analysis of six jack pine populations along a north-south transect through the MacKenzie River Valley in the Northwest Territories revealed no significant latitudinal trends in cone and seed morphometric measurements. In attempting to determine whether any variations may be environmentally induced, Radial Growth Rates were, 1)compared between sites. and 2), were correlated with morphometric measurements. No significant results were produced. In correlating trait measurements between sites and between one another in order to determine whether migration may be producing trends, again no significant relatlonships were obtained. A comparison of jack pine with the similar species lodgepole pine suggests that if the same factors controlling the migration of lodgepole pine also control jack pine migration, wing loading should be less in more recent populations. However, this study indicates no significant results in this respect. It is suggested, however, that a further sampling south along the latitudinal transect may produce significant results.</p> / Thesis / Candidate in Philosophy

The research described in this thesis examines how the hydrologic cycle is affected by climate changes in the Mackenzie River Basin (MRB) in northern Canada. The study focuses on five hydro-meteorological variables; runoff, evapotranspiration, storage, temperature and precipitation. Two different climate input data sets were used: Environment Canada gridded observed data and the European Center for Medium range Weather Forecasting (ECMWF) Re-Analysis climate data (ERA-40). In both data sets, runoff and evapotranspiration were modelled using the WATFLOOD hydrological model for the period of 1961 to 2002 on a 20 by 20 km grid. Trends were assessed on a monthly and annual basis using the Mann-Kendall non-parametric trend test. The hydrologic cycle in the MRB appears to be strongly influenced by climate change. The results reveal a general pattern of warming temperatures, and increasing precipitation and evapotranspiration. Overall decreases in runoff and in storage were detected from the Environment Canada data set while increases in runoff and in storage were detected from the ECMWF data set. The trends in runoff and evapotranspiration reflected changes in both precipitation and temperature. The spatial pattern of changes in runoff followed the pattern of change in precipitation very closely in most of the months, with the exception of March and October. The effect of changes in temperature is much more noticeable than that of changes in precipitation in March and October. The change in spatial distribution of evapotranspiration, on the other hand, matched the pattern of changes in temperature better; yet its seasonal pattern follows more closely to that of precipitation. The sensitivity of annual runoff to changes in climate was also estimated using a nonparametric estimator. Among the most important findings are: 1) runoff was more sensitive to precipitation and less sensitive to temperature; 2) runoff was positively correlated with precipitation and evapotranspiration; 3) runoff was negatively correlated with temperature, implying any increase in melt runoff from glaciers caused by increases in temperature were offset by losses due to evapotranspiration within the basin; 4) soil moisture storage may play an important role in the runoff and evapotranspiration processes; and 5) the sensitivity of mean annual runoff to changes in precipitation and evapotranspiration is typically lower along the Rocky Mountain chain, higher in the central zone of the Interior Plain, and highly varied in the Canadian Shield region in the basin. Correlation analysis suggested that the agreement between the two data sets is very weak at the grid-cell level. However, there was broad degree of consistencies in the seasonal and spatial patterns of trends between the two data sets, suggesting that the data are more reliable for identifying hydrological changes on a regional scale than at grid-cell level.

The research described in this thesis examines how the hydrologic cycle is affected by climate changes in the Mackenzie River Basin (MRB) in northern Canada. The study focuses on five hydro-meteorological variables; runoff, evapotranspiration, storage, temperature and precipitation. Two different climate input data sets were used: Environment Canada gridded observed data and the European Center for Medium range Weather Forecasting (ECMWF) Re-Analysis climate data (ERA-40). In both data sets, runoff and evapotranspiration were modelled using the WATFLOOD hydrological model for the period of 1961 to 2002 on a 20 by 20 km grid. Trends were assessed on a monthly and annual basis using the Mann-Kendall non-parametric trend test. The hydrologic cycle in the MRB appears to be strongly influenced by climate change. The results reveal a general pattern of warming temperatures, and increasing precipitation and evapotranspiration. Overall decreases in runoff and in storage were detected from the Environment Canada data set while increases in runoff and in storage were detected from the ECMWF data set. The trends in runoff and evapotranspiration reflected changes in both precipitation and temperature. The spatial pattern of changes in runoff followed the pattern of change in precipitation very closely in most of the months, with the exception of March and October. The effect of changes in temperature is much more noticeable than that of changes in precipitation in March and October. The change in spatial distribution of evapotranspiration, on the other hand, matched the pattern of changes in temperature better; yet its seasonal pattern follows more closely to that of precipitation. The sensitivity of annual runoff to changes in climate was also estimated using a nonparametric estimator. Among the most important findings are: 1) runoff was more sensitive to precipitation and less sensitive to temperature; 2) runoff was positively correlated with precipitation and evapotranspiration; 3) runoff was negatively correlated with temperature, implying any increase in melt runoff from glaciers caused by increases in temperature were offset by losses due to evapotranspiration within the basin; 4) soil moisture storage may play an important role in the runoff and evapotranspiration processes; and 5) the sensitivity of mean annual runoff to changes in precipitation and evapotranspiration is typically lower along the Rocky Mountain chain, higher in the central zone of the Interior Plain, and highly varied in the Canadian Shield region in the basin. Correlation analysis suggested that the agreement between the two data sets is very weak at the grid-cell level. However, there was broad degree of consistencies in the seasonal and spatial patterns of trends between the two data sets, suggesting that the data are more reliable for identifying hydrological changes on a regional scale than at grid-cell level.

No description available.

Broad whitefish, Coregonus nasus, is an important subsistence fish species in Arctic North America, yet virtually nothing is known regarding the genetic population structure of Nearctic populations of this species. In this thesis, microsatellite DNA variation was assayed among 1213 broad whitefish from 47 localities throughout North America, with emphasis on the Mackenzie River system, Northwest Territories. Specifically, I examined geographic variation in allele frequencies to assess how historical factors (Pleistocene glaciations) have shaped the current structuring of genetic variability and population differentiation. Microsatellite data was also used to resolve the relative contributions of broad whitefish populations to subsistence fisheries in the Mackenzie River system. Overall, broad whitefish exhibit relatively high intrapopulation microsatellite variation (average 12.29 alleles/locus, average HE = 0.58) and there were declines in these measures of genetic diversity with distance from putative refugia suggesting historical factors, namely post-glacial dispersal, have influenced current microsatellite variation. Interpopulation divergence was low (overall FST = 0.07), but the main regions assayed in this study (Russia, Alaska, Mackenzie River and Travaillant Lake systems) are genetically differentiated. Strong isolation-by-distance among samples was resolved when including only those populations occupying former Beringia, but not when assaying those at the periphery of the range in the Mackenzie River system, suggesting that broad whitefish in the Mackenzie system have not occupied the region long enough since their invasion post-glacially to have approached equilibrium between gene flow and drift. Mixture analysis indicated that most fish from the lower Mackenzie River subsistence fishery originated from the Peel River, highlighting the importance of this tributary. Additionally the mixture analysis provides evidence for a putative riverine life history form in the Mackenzie River. My results indicate that glaciation and post-glacial colonization have been important in shaping the current genetic population structure of North American broad whitefish. They also illustrate the utility of microsatellite DNA to delineate population structure and patterns of genetic diversity in recently founded populations in addition to resolving contributions to fisheries. My data also support the hypothesis that there are several designatable units of conservation among broad whitefish populations and that management strategies should be implemented accordingly.