NWT RESEARCH DATABASE

Regions: Dehcho Region, South Slave Region

Tags: physical sciences, water quality, organic carbon

Objective(s): To develop a sophisticated model that can simulate the mobilization, transport, transformations, and export of tDOC from the Mackenzie River watershed to the Arctic Ocean.

Project Description: This licence has been issued for the scientific research application No.5291. The primary objective of this project is to develop a sophisticated model that can simulate the mobilization, transport, transformations, and export of Terrigenous Dissolved Organic Carbon (tDOC) from the Mackenzie River watershed to the Arctic Ocean. The model will be used to simulate the transfer of tDOC during the past two decades and for plausible future scenarios. As part of the project, the research team will conduct multiple field campaigns to collect crucial data that will facilitate the development and validation of that model. To achieve this objective, the team will need to collect field measurements by deploying optical water-quality probes and other optical instruments; water samples for analyses and experiments carried out in the laboratory at Boston University. The team will also collect field measurements to develop better algorithms that will facilitate the accurate mapping of surface water-quality indicators (turbidity, algae, tDOC) from National Aeronautics and Space Administration (NASA) ocean-color satellites in Great Slave Lake, as well as in the Mackenzie River and its primary tributaries. Final deliverables from this project will include: 1) a significant data set of water quality measurements, 2) a modeling framework of tDOC transfer in the Mackenzie River, 3) simulations of tDOC transfer for past two decades and the near future, analyses of change, 4) maps of water quality indicators of Great Slave Lake, the Mackenzie River and its primary tributaries (e.g., Liard, Hay, Slave) derived from NASA satellite sensors, and 5) graduate student training (Ph.D. dissertation and peer-reviewed publications). For the field work effort, the team hope to be able to leverage help from the local communities of Fort Simpson, Hay River, Fort Providence, and Fort Resolution. Marlene Evans (Environment and Climate Change Canada), who is collaborator on the NASA project, will serve as a link between PI FIchot/Co-I Kaiser and the local communities. She is also helping to develop a companion ECCC program for remote sensing studies of Great Slave Lake and measurements of productivity (chlorophyll). The research team will conduct field work during each year of the 3-year project. In 2022, the team will conduct a scoping trip during the first two weeks of July for some limited sampling and data collection in the tributaries of the Mackenzie River and Great Slave Lake, and to meet and engage with the local communities of Fort Simpson, Fort Resolution and Hay River. In both 2023 and 2024, the team will conduct two more intense field campaigns in May (2 weeks) and September (2 weeks) of each year. During our field efforts, the team hope to engage some members of the local communities in some limited capacity in the sampling activities through the use of local boats to sample on Great Slave Lake, and to help with water sampling when we are not present in the field. In 2022, the team will collect optical and water-quality data and water samples at different times and multiple locations in Great Slave Lake, the Hay River, Liard River, Mackenzie River (Fort Providence area), Slave River, and opportunistically in smaller river in-between (Buffalo, Little Buffalo). Optical and water-quality data and water samples will be collected as follows: 1) Water-quality indicators from a YSI EXO-3 sonde equipped with a temperature-salinity probe, a chlorophyll-a fluorescence probe, a dissolved organic matter fluorescence probe, a turbidity probe, and a dissolved oxygen probe. The sonde will be dunked in the water and will be used to acquire data for 2-3 minutes while a water sample is collected at the same time; 2) Water reflectance (color of the water) will be measured at the sampling sites using an ASD handheld spectrometer. This is an above water measurement that is equivalent to taking a picture. 3) A water sample will be collected at each sampling site. The sample will be filtered on site using a simple syringe + in-line filter apparatus (0.7-micrometer pore size). The filtrate will be collected in a 40-mL small glass vial and analyzed at Boston University for dissolved organic carbon (DOC) (using a Shimadzu TOC-V analyzer) and Chromophoric Dissolved Organic Matter (using a Perkin-Elmer Lambda 650 spectrophotometer). The filter itself will also be kept and analyzed for particulate organic carbon (POC) at Boston University (using a Costech CHN elemental analyzer). In 2023 and 2024, the team will follow a similar sampling plan as in 2022 through the field work will be conducted at the beginning of the ice-free season during the freshet (May) and in late summer. The team also plan on carrying out long-term deployments of three YSI EXO-3 sondes in the Hay River, Liard River, Slave River, and possibly a fourth one the Mackenzie River near Fort Providence area. The sondes would be deployed in May during the first visit and would continuously record water-quality indicators (temperature-salinity, chlorophyll-a fluorescence, dissolved organic matter fluorescence, turbidity, dissolved oxygen) until they are recovered in September during our second visit. As part of this field effort, the team hope to engage some members of the local communities to inspect the sondes (check for biofouling, replace battery) and collect occasional samples at the sites between the first and second visit. Communication of results will occur through several venues including telephone calls, emails, zoom meetings, and in-person meetings during the entirety of the project. The team will also visit Hay River, Fort Resolution, and Fort Simpson each year to discuss the study, show results, and address questions. The results of the greater NASA project will also be communicated each year by the PI and co-I teams at the NASA ABoVE science team meetings and at international science meetings such as the American Geophysical Union meeting in the late Fall of each year. The team have already attended multiple Zoom meetings, organized with Fort Resolution, Fort Simpson, and Hay River and have had telephone conversations/email communications with Fort Providence, and the Fort Resolution and Hay River Metis. The team have also had Zoom conversations with GNWT Environment, during which the team discussed how to coordinate the proposed sampling with their community-based water quality program and related studies. Marlene Evans (Environment and Climate Change Canada) who is collaborator on the NASA project, will serve as a link between PI FIchot/Co-I Kaiser and the communities and will facilitate communication. The fieldwork for this study will be conducted from July 22, 2022 to December 31, 2022