Title: Net ecosystem exchange (NEE) of a permafrost peat plateau
Citation: Laurion, I., Prekienis, V., Billet, M., Bouchard, F., Fortier, D., & Rautio, M. (2016).
Influence of geomorphology and organic matter lability on the variability in greenhouse gas emissions from tundra lakes. NWT Discovery Portal. https://nwtdiscoveryportal.enr.gov.nt.ca/geoportal/catalog/search/resource/details.page?uuid=%7B8E570BE0-7534-4F70-9CB2-43950D0FD0BC%7D
Study Site: Qarlikturvik Valley, Bylot Island, Nunavut
Purpose: Aquatic environments can be considered as ecological hot-spots in barren high-arctic tundra landscapes. Permafrost instability caused by climate change leads to increased transportation of organic-rich matter to these biologically active ecosystems, potentially influencing the global carbon budget. The objectives of this study are to: 1- Measure ebullitive and diffusive CH4 and CO2 fluxes from tundra lakes, varying in shape and size; 2- Describe the properties of organic-rich soils presently or potentially accessible to the aquatic microbiota, and evaluate their lability; 3- Determine to what extent the morphology of water bodies, the properties of the water column, and the flux of organic carbon from surrounding soils are controlling lake emissions of CH4 and CO2.
Abstract: The PhD fieldwork spans from summer 2014 to summer 2016, however this project relies on the limnological research conducted continuously on Bylot Island since 2005. Limnological profiles were done with a YSI multiparameter probe (T°, pH, conductivity, oxygen). Discrete water samples were collected for nutrients, major anions and cations, dissolved organic matter (Dissolved organic carbon (DOC) and colored dissolved organic material (cDOM) absorption spectra), total suspended solids following standard methods. Discrete measurements of CO2 flux at the water interface were taken using a floating chamber connected to an IRGA (EGM-4, PP-Systems), CO2 and CH4 fluxes were also estimated using dissolved gas concentration and gas transfer models. Ebullition flux was measured using inverted funnels (inspiration from Wik et al. 2013) to collect bubbles for further analysis (gas chromatography, stable isotopes, 14C dating). Bathymetry of larger lakes was obtained with sonar (Bouchard et al. 2015), while a high precision integrated positioning system (GNSS, Trimble R8) was used for shallow ponds. Lake sediment cores were extracted using gravity (Mini-Glew) and percussion corers. Permafrost cores down to 1 m depth were taken with a portable earth-drill system (Calmels et al. 2005). Cores were analysed for loss of ignition (LOI), water content, bulk density, and carbon and nitrogen contents. Fatty acids were analysed in subset of soil samples. Depending on the stratigraphy, selected core layers were incubated over short-term (weeks) under in-situ or laboratory conditions to evaluate the potential of these different carbon sources to fuel microbial activity. During the experiments O2, CO2, CH4, DOC, and optical DOM properties were followed.
Supplemental Information Summary:
Research:
Further Info:
Status: Complete
Keywords:
carbon dioxide,
methane,
remote sensing,
peat properties,
dissolved organic carbon,
Climate change,
Geographical coordinates: North: 73.1, South: 73.1 East: -80 West: -80
Bounding Temporal Extent: Start Date: 2014-06-01, End
Date: 2016-08-31
