Base de données de recherche des TNO

étiquettes: physical sciences, water quality, permafrost, climate change, methane

Objectif(s): To identify impacts of climate change and permafrost thaw on pond methane emissions, and on water chemistry in streams that drain peatland-rich catchments.

Description du projet: The objective of this research is to identify impacts of climate change and permafrost thaw on pond methane emissions, and on water chemistry in streams that drain peatland-rich catchments. Impacts on methane emissions will be assessed. Specific objectives are : 1) to characterize the trends and variability in magnitude of methane emission from ponds along climate gradients within both the Taiga Plains and Shield regions of the Northwest Territories (including further sites in Alberta and Saskatchewan);. 2) to investigate the influence of permafrost thaw on methane emissions from peatland ponds on the Taiga Plains; and, 3) understand the impacts of permafrost thaw on water quantity and quality in streams draining peatland-rich catchments. The research team will measure methane emissions from ponds in various regions and latitudes across the NWT and also include sites in Alberta and Saskatchewan. This research will be done over the span of three summers. First, the team will measure emissions from 5 to 10 lakes at each of the four NT locations, near Fort McPherson, Tuktoyaktuk, Yellowknife, and Wrigley. This will be done between 1 and 4 times per season, depending on site and year. The team will use a state of the art, portable gas analyzer (LGR, USA) to measure methane emissions. This is a non-invasive approach, during which floating chambers are used to capture methane gas coming from the surface of the water. The team will reach the centers of the lakes using inflatable kayaks. General water characteristics, including temperature, pH, conductivity, and dissolved oxygen will be measured using a handheld sensor. Water samples will be collected from the ponds for further analyses. In order to better predict what pond characteristics best explain variability in methane emissions across the Northwest Territories, the research team will characterize ponds with regards to sediment type (peat or mineral) and sediment thickness, dominant surrounding ecosystem types, pond size and shape, and water chemistry. This will allow the team to identify the primary controls on methane emissions across a large climate gradient and across regions with very variable surface geology. For the second component , the research team will establish continuous monitoring of discharge and water quality at Smith Creek (near Wrigley) and Scotty Creek (near Jean Marie River) outflows, and at a sub-catchment outflow within Smith Creek catchment. Continuous stream measurements will include stream stage, using pressure transducers, electrical conductivity, temperature, and absorbance across the full UV-vis spectra. The UV-vis spectra will yield information on turbidity, and on the quantity and chemical composition of dissolved organic matter (DOM). This instrumentation has recently been used at Scotty Creek, and monitoring at Smith Creek will thus yield comparable data. Manual grab samples will be taken at least bi-weekly from late May to late October. Manual water samples will be analyzed for pH, turbidity, dissolved oxygen, major ions, total organic carbon and total nitrogen, and DOM analysis of optical properties through UV-vis absorbance and fluorescence. The team will at the Smith Creek site collect permafrost peat cores for soil analysis, which will allow to understand the potential role of permafrost thaw for catchment delivery of solutes. The monitoring program will allow to understand controls of contributions from different catchment water sources, and their influence on solute export and water quality. Local community members will have the opportunity to be trained as field technicians. Field technicians will be responsible for collecting water samples from accessible lakes and streams during the summer months. The technicians will accompany the team during the first few field campaigns and will then be responsible for collecting water samples when during times when the research team is not at those locations. This will allow the team to take samples more frequently, providing high-resolution insights to how the water chemistry changes in lakes and catchments over the course of the summer. There will also be an opportunity for locals to survey the lakes during the fall and in the spring in order to record with the lakes freeze and thaw, respectively. School children will have a chance to learn about the research and general climate change science in the Northwest Territories through educational presentations and outreach. The research team will present the research to the communities through plain language, educational posters and reports. Specifically, the team hope to present this research to local schools (Fort McPherson, Fort Simpson, Yellowknife) and museums (Hay River). During the summer months, when school is not in session, the team will make the research goals and objectives available to locals through informational materials at community centers. Importantly, the research team aim to communicate the research to the communities during all stages of the project, including data collection (fieldwork) and the writing of the final reports. The fieldwork for this study will be conducted from May 1, 2019 to October 31, 2019.