NWT RESEARCH DATABASE

Tags: permafrost, geochemistry, metals, soil chemistry, organic carbon

Objective(s): The objectives of the project are to: (1) investigate geochemical variations in the uppermost 3-5m of permafrost in the western Canadian Arctic; (2) assess potential geochemical implications of anticipated permafrost thaw on terrestrial and aquatic systems; (3) examine soil cryoturbation in the active layer using isotope tracers, and (4) determine if the rate of cryoturbation is affected by varying soil moisture.

Project Description: The proposed project is a collaborative work between academic researchers, the NWT Geoscience Office and local communities. The objectives of the project are to: (1) investigate geochemical variations in the uppermost 3-5m of permafrost in the western Canadian Arctic; (2) assess potential geochemical implications of anticipated permafrost thaw on terrestrial and aquatic systems; (3) examine soil cryoturbation in the active layer using isotope tracers, and (4) determine if the rate of cryoturbation is affected by varying soil moisture. Objectives 1 and 2. Investigate geochemical variations in the uppermost 3-5m of permafrost in the western Canadian Arctic permafrost and assessing potential geochemical impacts of permafrost degradation on terrestrial and aquatic systems. The purpose of this component is to measure geochemical variations in the upper 3-5m of permafrost in various terrain units between Tsiigehtchic and Inuvik. This will provide the basis for a geochemical comparison that will address whether changes due to permafrost degradation can be expected uniformly across the landscape. This objective will be accomplished by collected samples from the active layer (every 5cm) and coring the permafrost with a SIPRE-type corer with a core barrel 3.5 inches in diameter. At each site, the research team will collect 2-3 cores to a depth of 3-5m. These cores will be sectioned in the field in 2-3cm thick slices and analyzed back in the laboratory for water content, soluble ions and trace metals, concentration of organic carbon, nitrogen and sulfur and their stable isotope in the sediments. Objectives 3 and 4. Examine soil cryoturbation in the active layer using isotope tracers and determine if the rate of cryoturbation is affected by varying soil moisture. For these objectives, the research team will use the active layer and permafrost cores collected above. The samples will be analyzed for pore water tritium (³H), organically-bound tritium (OBT), caesium-137. The OBT and Cs-137 radioactive isotopes bound preferentially to organic carbon and soil particles, respectively. As such, an investigation of their concentration with depth in the active layer and shallow permafrost allows the team to assess the rate of soil movement due to cryoturbation. This is a novel concept that has yet been applied to permafrost regions and as such will provide the first measurements from this environment. The results are expected to increase knowledge on the rate of formation and collapse of hummocks. Project results will be shared within the scientific community through various conferences, both national and international, and peer-reviewed publications. The research team is planning on presenting results to the local communities through school workshops; these presentations would be offered using the Let’s Talk Science workshop method developed by Science Travels. These outreach programs are mainly aimed at teenagers and school-aged children, but would be open to all interested members of the community. The fieldwork for this study will be conducted from June 15, 2014 to August 31, 2014.