NWT RESEARCH DATABASE

Regions: Inuvialuit Settlement Region, Gwich'in Settlement Area

Tags: physical sciences, water sampling, soil, sediment, freshwater ecosystem, nitrogen, terrestrial ecosystem, phosphorus

Objective(s): To quantify and characterize Nitrogen (N) pools along the riparian-stream continuum, 2) to determine the amount of available N for biological assimilation (i.e. gross ammonification), and 3) to evaluate the main drivers of N pools and processes (i.e. vegetation, lithology, soil type and geomorphology).

Project Description: This licence has been issued for the scientific research application No.5034. The main aim of Nitrofresh is to assess the nitrogen (N) sources for streams and the linkages between terrestrial and freshwater ecosystems across different regions with continuous permafrost in High Arctic. In particular, the research team have three objectives: 1) to quantify and characterize N pools along the riparian-stream continuum; 2) to determine the amount of available N for biological assimilation (i.e. gross ammonification); and, 3) to evaluate the main drivers of N pools and processes (i.e. vegetation, lithology, soil type and geomorphology). At each sampling site, samples will be obtained for stream water (2L), stream sediment (300mL) and soils (for each sampling site: 5 locations x 2 profiles x 300mL). Moreover, a description of the site (vegetation, lithology, soil type, and geomorphology) will be conducted in-situ. Samples will be shipped frozen to Aarhus University (Denmark) for further analyses. The water sample will be grabbed with a clean 2L bottle, filtered for microbial and chemical analyses. The soil samples will be sampled at 0-40 cm depth using a handheld corer, and if possible include permafrost samples. The sample will be placed in zip-bags and frozen. The characterization of the samples will be done by measuring temperature, conductivity, pH, and active layer depth. For these four compartments, the team will then measure: Nitrogen pools including both inorganic and organic forms. Both filtered water, and soil and sediments (extracted with KCl) will be analyzed at Aarhus University facilities using a Lachat QC-8500 Flow Injection Autoanalyzer and ShimadzuTOC-analyzer. Nitrate isotopes of water to estimate nitrification rates (i.e. the conversion of the conversion of Ammonium ion to Nitrate) and bulk N isotopes of soil/sediments. Samples will be send to UC-Davis facility for analyses for nitrate. Water isotopes (d2H and d18O) and cations for hydrological characterization. For sediment and soil samples, the team will measure. Gross ammonification is the total amount of organic N mineralized into ammonium and is therefore an indicator of the amount of N available for biological assimilation, transformation and export downstream. Other soil characterization measures will include loss-of-ignition measure for organic matter quantification and soil type determination. At the beginning of the project, the Principal Investigator (PI) will communicate the objectives and main tasks of the project planned and we will evaluated outreach opportunities outreach from abroad. The PI will be open to participate at Aurora “Speaker Series” that has the objective to strengthen public awareness. During the project, main milestones of the project will be announced on Twitter. At the end of the project, the PI will elaborated a final report of the results obtained that will be distributed to Aurora Research Institute and will be available to any person to access it. This will contain the contact information of the main researcher to be able to reach out. The fieldwork for this study will be conducted from August 18, 2021 to September 30, 2021.