Sources and fate of microplastics in Great Slave Lake

Regions: Dehcho Region, North Slave Region, South Slave Region

Tags: physical sciences, sediment chemistry, water sampling, Mackenzie River, Great Slave Lake, Microplastics

Principal Investigator: Bourdages, Madelaine (4)
Licence Number: 17023
Organization: Carleton University
Licensed Year(s): 2022 2021
Issued: May 05, 2022
Project Team: Madelaine Bourdages, Jesse Vermaire

Objective(s): To quantify microplastic concentration and composition in water, sediment, zooplankton, and air around Great Slave Lake; to examine if microplastic concentrations are greater near communities than the open water of Great Slave Lake; and to identify whether Great Slave Lake is a source of microplastics to the Mackenzie River.

Project Description: This licence has been issued for the scientific research application No.5224.

The first objective of this project is to quantify microplastic concentration and composition in water, sediment, zooplankton, and air around Great Slave Lake. The second objective of this project is to examine if microplastic concentrations are greater near communities than the open water of Great Slave Lake. The third objective of this project is to identify whether Great Slave Lake is a source of microplastics to the Mackenzie River.

To meet the research objectives, surface water, subsurface water, benthic sediment, beach sediment, zooplankton, and air samples will be collected from Great Slave Lake aboard the R/V Nahidik. Surface water samples will be collected using a 300 micrometer Manta trawl that will be dragged alongside the ship for 20 minutes. Water samples will also be collected below the surface of the water using a peristaltic pump. Both types of water samples will be filtered immediately on site. Approximately 400 g (wet weight) of benthic sediment will be collected from shallower, near shore sites using an Ekman Grab sampler and immediately transferred into glass jars. A short gravity corer will also be used to collect some sediment cores at deeper sites within Great Slave Lake. If the ship goes to shore at any point, beach sediment samples will be collected by scooping sediment from the top 5 cm into glass jars using the jars themselves as scoops. Zooplankton samples will be collected by sieving the surface water for approximately 10 minutes using a zooplankton net. While water and benthic sediment samples are being collected, Petri dishes with double sided tape will be opened and left exposed for the duration of water and sediment sample collection to collect data for atmospheric deposition of microplastics.

In addition to the sampling done from the R/V Nahidik, water, sediment, zooplankton, and air samples will be collected around Yellowknife and within Yellowknife Bay using the same methods as previously outlined. Ideally, a small boat will be chartered to allow for this sampling within Yellowknife Bay, however, this will only occur if COVID-19 is no longer a risk to communities and if the work is deemed safe by the community. Alternatively, samples around Yellowknife will be collected from publicly accessible beaches and shorelines. Passive air samplers will also be installed in Yellowknife to collect data for atmospheric deposition over a longer period of time. Filters from the passive air samplers will be changed every week, and all equipment will be removed at the end of the study period.

In summer 2021, the research team worked with the North Slave Métis Alliance (NSMA) to collect samples from the Yellowknife River and Yellowknife Bay. The research team have discussed plans for additional sampling in Yellowknife, and have support from the NSMA to continue this work. In summer 2021, the team also worked with the Fort Resolution Métis Government (FRMG) to collect samples around Fort Resolution and in the Slave River. The team have discussed plans for additional sampling in Fort Resolution in 2022, and we have support from the FRMG to continue this work. Additionally, we have submitted a funding application to the Cumulative Impact Monitoring Program for the work in Fort Resolution with the support from the FRMG. The team have also discussed conducting additional work in Fort Providence with the Dehcho Aboriginal Aquatic Resource and Oceans Management (AAROM), and they have expressed interest and support for this project. The team plan to present the research and all research findings at the Yellowknife Geoscience Forum as well directly to communities. A plain language report will be produced at the end of the project and distributed to the communities and organizations involved in the project.

The fieldwork for this study will be conducted from July 4, 2022 to September 30, 2022