NWT RESEARCH DATABASE

Tags: water quality, active layer, permafrost, cumulative effects, carbon dioxide, methane, ground penetrating radar, organic carbon, soil moisture, peat, ultraviolet radiation

Objective(s): To quantify surface energy balances in areas where degradation of peat is pronounced and where it is not; and to conduct experiments on dissolved organic carbon (DOC) source water (eg., groundwater) to determine the chemical changes (labile and recalcitrant) to DOC when it is exposed to sunlight (ultraviolet radiation).

Project Description: This research is physically based on a peat plateau and a peat bog, both close to Yellowknife. There are two primary objectives to this research. The first involves quantifying surface energy balances in areas where degradation of peat is pronounced and where it is not. Suprapermafrost water from the degraded and non-degraded sites will be analyzed for nutrients and dissolved organic carbon (DOC) as well as labile and recalcitrant DOC species. Airspace in the vadose zone above the water table will be analyzed for decomposition gas by-products (carbon dioxide and methane). Secondly experiments on DOC source water (eg., groundwater) will be run to determine the chemical changes (labile and recalcitrant) to DOC when it is exposed to sunlight (ultraviolet radiation). Understanding these changes helps understand the implications of DOC seeping into surface waters via groundwater seeps. At the two research sites, active layer... Show more and permafrost temperatures have been recorded over the past two years. The sites were chosen for accessibility and because there is a data record for both. At both sites three sets of Hobo data loggers will be installed to record changes in soil moisture and temperature. The instruments will be installed along a gradient extending from the degraded peat to the peat that is not visually degraded. At each site air temperature and relative humidity is recorded. At some point in time small diameter (10cm) cores extending from the surface to a depth approximately 80-100cm below the permafrost table will be extracted and stored in a freezer for later work. Each two weeks during the thaw season depth to the frost/permafrost table will be recorded along several transects. During the summer period the site will be surveyed using a Leica GPS system (horizontal and vertical accuracy: +/- a few centimeters). As well, in order to differentiate the spatial distribution of subsurface physical characteristics a MALA ground penetrating radar system will be employed. Surveys will be done along the transects used for the two-week frost probe surveys and during the winter at a time when maximum freezing is indicated from the Hobo dataloggers and during October when the active layer is at maximum development. Shallow piezometers will be installed in different parts of the two sites where peat degradation is and is not apparent; suprapermafrost water will be extracted through these standpipes for nutrient (nitrate-n, ammonium and total phosphate) and DOC analysis. Sippers (metal tubes) will be extended into the unsaturated portion of the peat to sample the decompositional gas byproducts (carbon dioxide, methane). Samples (10L) of different subsurface groundwater will be extracted for experimental exposure to sunlight (ultraviolet radiation) in the lab. Nutrients will be analyzed on a Dionex Chromatograph or a Technicon Autoanalyzer (depending on the concentration) and DOC will be analyzed on a Shimadzu Total Carbon analyzer. To determine the molecular makeup of the DOC a Liquid Chromatograph- Organic Carbon Detector using a Toyopearl HW-50S size-exclusion column is used. At the annual Cumulative Impacts Monitoring Program meeting (held in the winter) the research team will present the results and the data will make its way to the Cumulative Impacts Monitoring Program open website data inventory (NWT Discovery Portal). Once the research team have data they will discuss with the various government researchers in Yellowknife what the best way of communicating the data to First Nations groups and other interested persons. The fieldwork for this study will be conducted from September 6, 2013 to December 20, 2013. Show less