Base de données de recherche des TNO

étiquettes: permafrost, climate change, ancient plants, stable isotopes

Objectif(s): To collect frozen core samples from the top of permafrost and soil from the active layer; to interpret ancient permafrost and leaf waxes in Northwestern Canada and to reconstruct Late Quaternary climate change.

Description du projet: The primary objectives of this research project are to collect frozen core samples from the top of permafrost and soil from the active layer. Boreal sites will be targeted. The stable isotope compositions of ice and leaf waxes from the samples will be measured. Samples collected from NWT will be added to a much larger Yukon dataset, and the relations between regional climate and the proxies will be quantified. This analysis will provide a firm basis for interpreting ancient permafrost and leaf waxes in Northwestern Canada, and reconstructing Late Quaternary climate change. Permafrost cores and soil samples: A small pit (2’ x 2’) will be dug to the base of the active layer (unfrozen ground). Three pits will be sampled at each site. Soil samples will be collected from the walls of the pit at 10 cm intervals and stored in plastic bags (ca. 100 mL soil/sample). A 2-man drill with a 4” diameter core barrel will be used to collect a core from the upper metre of permafrost. Following sample collection, the pits will be re-filled with the original sediments and capped with the original turf to return the site to its natural state. Samples will be stored in a generator-powered freezer in the field, and driven to the University of Alberta for further processing. Leaf waxes will be extracted from the unfrozen and frozen sediments, and the stable hydrogen isotopes of these compounds will be measured at the University of Ottawa by Gas Chromatography-Isotope Ratio Mass Spectrometry. Stable hydrogen and oxygen isotopes from the frozen pore waters will be analysed at the University of Alberta by Cavity Ring-Down Spectrometry. The field sampling described in this permit application is exploratory and will occur over a short timeline (half a day) at sites along the Dempster Highway, on our return trip to Yukon. If the samples collected during this exploratory work yield valuable results, future work along the NWT portion of the Dempster Highway would then be warranted. Future work would require more extensive sampling of this area, exclusively in the Gwich'in Settlement Area (but not on Gwich'in Private Lands). This work would benefit from local involvement, especially field guides who know the land more intimately and youth/students from Inuvik, Fort McPherson, and Tsiigehtchic who are interested to participate as field assistants and learn how water and leaf waxes in permafrost record past climate. All local residents involved would gain knowledge of scientific sampling for paleoclimate research. All three Gwich'in Councils in Inuvik, Fort McPherson, and Tsiigehtchic would be consulted on this work, and to inquire about local field guides and assistants. Upon completion of this project, a report documenting the project results would be distributed to the local Councils. The fieldwork for this study will be conducted from July 22, 2014 to July 24, 2014.