NWT RESEARCH DATABASE

Objective(s): To assess the viability of the Tibbitt to Contwoyoto Winter Road by analysis of sediment/water interface samples, freeze cores, and dendrochronology.

Project Description: In order to document climate variability that has impacted the TCWR corridor through the Late Holocene, it is important to distinguish subtle changes recorded in the sedimentary archives of examined lakes and tree-ring records. Characterization of these parameters using an integrated multi-environment, multi-parameter approach will allow us to recognize subtle paleolimnologic and paleoclimatic (principally temperature and precipitation) variation with more precision than is achievable using a single methodology. The investigator will quantify dominant scales and measurable characteristics of paleoclimate cycles and trends, and correlate them with continental climate signals recorded elsewhere in North America. The researcher will interpret the results in the context of subtle variations in the strength of the oceanographic domains and air masses that influence climate in the region. There are innumerable lakes found along the length of the TCWR. The 70 lakes chosen for micropaleontological and geochemical analysis of sediment-water interface samples and subset chosen for coring will be selected to span as broad a climatic gradient as possible. A suite of water property data parameters will also be collected from the lakes (e.g. pH, dissolved oxygen, temperature, conductivity) to better characterize our data for the development of accurate calibration training sets. The researcher does not anticipate that recent (26 year history) industrial winter transportation activity on these lakes will have a large impact on surface diatom communities because the large volume of water in targeted lake basins would probably dilute the small amount of contaminants entering the lakes. Regardless, the researcher will collect and analyze bulk water-sediment interface samples for contaminants and will include some lakes from off the route of the TCWR as controls. Detailed core analysis will be restricted to portions of core records deposited within the last ~3500 years, which encompasses the Late Holocene when modern circulation and climatic conditions developed. With the constraint of operating under extreme subarctic winter conditions, and for health and safety reasons, sites will be chosen within a 100 km radius of rest stops along the TCWR. These ‘bases’ will include the Lockhart Lake Rest Stop (175 km) at the tree line and Lac de Gras Rest Stop (350 km) on the open tundra, and also possibly the Dome Lake Maintenance Camp (DLMC; 25 km). With operations at the Jericho Diamond Project near Contwoyto Lake mothballed it will not be possible to sample the end of the TCWR, as the road is not currently maintained. To ensure consistency as we develop transfer functions for interpretation of core data, lakes selected for analysis will be of similar circular shape and simple morphometry. The investigator will also focus on undisturbed lake systems that are not significantly influenced by upstream lakes or rivers. Lake sediments will be collected using sediment coring devices and will be collected from basins no deeper than 4-5 m to minimize the impact of cold bottom water temperatures on the productivity of benthic biological proxies, as most lakes in the region are dimictic. Primarily winter field research will require use of a truck mounted augers supplied by the TCWRJV, and freeze coring equipment, water property sampling devices (modified Ekman grabs or Glew corers), as well as sub bottom imagery. Collection of dendrochronological cores will take place during summer, as it is not possible to core frozen trees. This research will require floatplane or helicopter support. As the supporting organizations are playing an integral role in the implementation of the research program they will have an ongoing understanding of the progress of the research. Co-investigators will also hold yearly meetings to brief stakeholders. This research will be of strategic importance to Canada in general, and the people of the Northwest Territories in particular, as it will provide sound scientific basis to guide policy makers and planners in their efforts to anticipate the impact of climate change on the viability of the TCWR. The first results from the project will be made available to stakeholders within two years of the start of the project and will be fully realized well within the National Science and Engineering Research Council Strategic Project Grant 10 year time frame. Preliminary research findings from this project were presented in November 2009 at the Yellowknife Geoscience Forum. We will continue to present research findings as the program progresses as various conferences and seminars. Publications arising from this project will be available to the public at the NWT-NTGO. Additionally, a website will be erected to transmit research updates and progress. As the supporting organizations are playing an integral role in the implementation of the research program, they will have ongoing communication and participation in the progress of the research. The fieldwork for this study will be conducted from April 2, 2010 to August 13, 2010.