NWT RESEARCH DATABASE

Regions: North Slave Region

Tags: mining impacts, arsenic, climate change, hydrology, wildfire

Objective(s): To explore how wildfire will affect the stability and fate of metals and metalloids (i.e. arsenic, mercury, antimony) in mining contaminated and pristine landscapes by contrasting metal(loid) concentrations in air, soil, and water in and around Boundary Creek (30 km west of Yellowknife) along burned (August 2023) and unburned reaches.

Project Description: This licence has been issued for the scientific research application No. 5898. The main goal of this project is to explore how wildfire will affect the stability and fate of metals and metalloids (i.e. arsenic, mercury, antimony) in mining contaminated and pristine landscapes. Metal(loid) concentrations in air, soil, and water in and around Boundary Creek (30 km west of Yellowknife) will be contrasted along burned (August 2023) and unburned reaches. Additional analyses of metal(loid) mineralogy in soil samples will help to elucidate the potential transformation of metal(loid)s by wildfire. Terrestrial and aquatic measurements will be supplemented with atmospheric metal(loid) measurements associated with wildfire smoke to measure the atmospheric remobilization of metal(loid)s and weigh the relative importance of these loads in the catchment cycling of contaminants. Sampling protocol is outlined below for each element of the system. The locations referenced below include: UBC (Boundary Creek where it is crossed by the highway), BBC (Boundary Creek, Downstream of the fire-affected region, about 5 km SW from UBC), SBC (a small burned catchment ~1 km NW from UBC), SUC (a small unburned catchment ~ 500 m NW from UBC), BW (a burned wetland adjacent to the gravel pit ~ 500 m SE from UBC), and UW (an unburned wetland right next to BW). Source Water Sampling - Snow surveys will be conducted in late March/early April of each study year to quantify the water stored in the snowpack (snow water equivalent), following standard protocols. - During snow surveying, snow samples will be collected (at the interface between the soil and the snow, as well as at the surface of the snow) for chemical analysis. - Locations: UBC (above ice), UBC shore, BBC shore (if accessible), SBC, SUC, BW and UW. - Summer precipitation will be collected at the site for chemical analyses, using a tipping bucket and precipitation sampler. Runoff Sampling - Weirs will be installed to capture surface water runoff during the spring melt (and any extremely high precipitation events in the warm season) - HOBO U20 water level loggers will be used to record stream water level to establish flow rate. - Manual timed runoff measurements will be used to calibrate the flows to water level. - Locations: BW & UW wetland slopes, SBC, SUC, tributary to Boundary Creek (access permitting) - Daily sampling of overland flow and water caught behind weirs will occur during the snowmelt period of every year - Shallow piezometers will be installed to collect groundwater flow in September 2024, and will be sampled weekly in the following study years. These nested systems will include a screened well (PVC) and a drive-point piezometer - Locations: BW and UW wetlands, Nested system near SUC and SBC - MacroRhizons will be installed in the active layer (three at each site, at depths of 0—5 cm, 5-10cm, and 10-20cm) to collect soil pore water for subsequent analysis - Weirs will be visited after heavy rainfall events in the summer of all years, and water samples will be collected if present. Stream Water Sampling - Weekly water samples will be collected during freshet in Boundary Creek reaches identified for the study using standard protocols and supported by ECC staff. - Bi-Weekly or monthly sampling will also occur at other streams across the region, including Miller Creek, Cameron River, Yellowknife River, Baker Creek, Marian River, and the Stagg River in collaboration with ECC, Water Monitoring and Stewardship as part of the North and South Slave water quality network. - Downstream samples in Boundary Creek will be taken 3 times (access permitting) over the spring/summer season, accessed by canoe. Soil Sampling - Soil samples were collected in 2023 to determine soil chemistry and arsenic mineralogy in burned and unburned areas near boundary creek. Soil surveys will be repeated each fall to evaluate changing soil chemistry and As mineralogy post-fire. - Locations: Gravel pit sites, SBC, SUC. Air Sampling - Archived air filters from Giant Mine from the 2023 fire season will be analyzed - Air filters from the Giant Mine site fenceline, and from the Great Slave Sailing Club, Ndilo, and Moyle Park will be collected - These samples are archived every 3 days and give a continuous record of the airborne metals and metalloids throughout the summer - Work will be done in collaboration with the Giant Mine Remediation Team to analyze remaining air filters for total metal(loid)s and As mineralogy The proposed project arises from ongoing community concern about arsenic deposition from Giant Mine and its subsequent mobilization through various processes including fire. In the first year of the project, the research team will endeavor to collect preliminary data in the form of water and soil samples, while developing a long-term research plan in collaboration with ARI, GNWT-WMS, University partners, and interested community members from the Yellowknife region, including the YKDFN and Tli?cho Government. This first community meeting will occur in late June 2024, and inform decisions on field equipment installation. Following this first meeting for project design, annual community meetings will serve as progress updates, providing an opportunity to deliver results to community members, discuss their implications in the local context, and seek approval for any proposed presentation of the results beyond the community context (e.g. conference presentations, publications). These meetings will also ensure that research methods continue to address community questions and provide an opportunity for community members to engage further in the project, reshape methodology, and re-assess project objectives. Options for increased engagement include participation in the YKDFN training program for environmental monitors through the Dechita Naowo program, with whom there has been collaboration in the past and hope for future collaboration. This program serves to translate practical scientific field data collection skills to environmental monitors. Trainees have participated in past CIMP funded projects with the project team, including a part-time hire in spring 2023 to evaluate runoff chemistry in the Pocket Lake catchment. The information generated from this study will be important for decision makers in the region, including regulatory agencies (MVLWB and MVEIRB), Indigenous governments, and the Territorial Government. Specifically, many of these decision-makers are responsible for assessing impacts of development related to pre-development baseline conditions. This project will help to inform how environmental baselines (including water quality) are changing with increased severity and frequency of wildfire. The remobilization of legacy contaminants from wildfire will be an important consideration for developments within the historical airshed of Giant and Con Mine. The fieldwork for this study will be conducted from: June 05 - September 30, 2024