Base de données de recherche des TNO

Régions: North Slave Region

étiquettes: permafrost, climate change, sediment

Objectif(s): To extract sediment cores from three different regions of the Northwest Territories namely: the low arctic tundra (continuous permafrost-Daring Lake), Taiga Shield northern boreal (widespread discontinuous permafrost-Wekweeti), and Taiga Shield boreal (sporadic discontinuous permafrost-Baker Creek Watershed) which provide the research team with a record back 100-150 years.

Description du projet: The objectives of this research project are: 1. to extract sediment cores from three different regions of the Northwest Territories namely: the low arctic tundra (continuous permafrost-Daring Lake), Taiga Shield northern boreal (widespread discontinuous permafrost-Wekweeti), and Taiga Shield boreal (sporadic discontinuous permafrost-Baker Creek Watershed) which provide the research team with a record back 100-150 years. Within each region cores will be taken from lakes with different terrestrial basin attributes (lake order, vegetation, fire history etc.); 2. to determine spatial and temporal variability of basin productivity- as determined by C/N- among the cores both within regions in terms of comparing the variability of the terrestrial systems draining into the lakes in question; 3to characterize and quantify Dissolved Organic Carbon (DOC) concentrations and chemical characterizations of DOC within different terrestrial source areas and aquatic environments; and, 4. to experimentally determine impacts on DOC and changes to the labile and recalcitrant DOC fractions by physical processes (temperature, soil moisture, solar radiation) and biochemical processes (microbial activity). Methods 1. Lake/basin productivity In each of the three regions described above, sediment cores will be extracted from three individual lakes, each with different basin characteristics but in term of terrestrial basin to lake surface ratio comparable among regions. Sediment cores will be extracted using a UWitec gravity sediment corer. Cores will be sectioned and dated using the 210Pb and 137Cs methods of detection. Carbon and nitrogen will be measured with an Elemental Analyzer (carbon and nitrogen) coupled with a Delta isotope ratio mass spectrometer (for d13C and d15N) at University of Waterloo. 2. Dissolved organic carbon and nutrients: In order to understand the fate and evolution of dissolved organic carbon in the northern environment specific attention will be placed on quantifying sources and changes in DOC concentrations and the chemical structure of DOC along terrestrial to surface water flowpathways during spring, summer and fall. In this regard specific flowpathways will be identified that are characteristic of the respective environments in these three regions. Some sites in the Yellowknife area are already (Northern Scientific Licence #15340) established for sampling flowpathways. Others will be established with the appropriate instrumentation (piezometers). DOC will be analyzed using a Shimadzu TNM-1 coupled with aTOC-L. As decomposition rates in these northern environments will likely rise the research team are interested in sources and changes in nutrients (NO3—N, P, NH4+) along these flowpathways. Sample extracted for these analyses will be run on a Dionex Ion Chromatograph at Laurier; low concentration samples will be run of a Technicon Autoanalyzer. 3. Experiments Small diameter peat cores will be extracted from the peatland study sites and experiments will be conducted on them in the lab (at the new Centre for Cold Regions and Water Science – part of the Government of the Northwest Territories-Wilfrid Laurier Collaborative Research Agreement). These experiments will be designed to determine the influences of environmental factors (e.g., temperature, sunlight, soil moisture) on changes in DOC and in the labile and recalcitrant fractions therein. Educational: Plans have been discussed with the local school teachers in Wekweeti to institute a science project next year on sampling snowfall. The plan would be to have two projects: one that the younger students could get involved in simple measurement of day-to-day snowfall and attending a talk one of us provides about snow and caribou. The other project would be more detailed and involve the older students and would comprise of regular measurements of the snowpack including depth, density and changes in snow crystal size. A talk would be given by one of the research team to talk about how they use satellite data to interpret the changing snowpack. Cultural: Meetings will be held with local elders, hunters and those interested to explain what the research team are doing (using satellite data to interpret snowpack changes) and to listen to their views on how the snowpack has changed and if they have noticed changes how they think those changes relate to any changes in caribou migratory behavior or their general well-being. Wekweeti: Results will be presented at a meeting of those community members interested in attending. Yellowknife: Through contacts in the Environment and Natural Resources Ministry of the GNWT the research team will meet with representatives of the Yellowknives Dene First Nation and North Slave Metis Association and discuss the project. The data will be entered into the Cumulative Impacts Monitoring Systems (CIMP) open website data inventory (NWT Discovery Portal). Where opportunities permit such as at the CIMP annual conference our data will be presented either orally or by poster. As Daring Lake is in the Tlicho claim results and updates can be provided to the people in Wekweeti. To assist with this, information will be provided to the Wek'eezhii Land and Water Board both in Yellowknife and in Wekweeti. The fieldwork for this study will be conducted from July 10, 2014 to August 29, 2014.