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Featured Presentation:
Microplastics in Muskoka-Haliburton headwater lake catchments
Brittany Welsh, PhD student, Trent University
Microplastics are pervasive contaminants of concern, but the fate of microplastic pollution in headwater lakes, especially in more remote regions, remains relatively unknown. This is evident by the lack of field studies to quantify the inputs, outputs and movement of microplastics to lakes at the watershed level. In this study, microplastics (MP) were identified and quantified over a 12-month period for three headwater lake catchments in Muskoka-Haliburton. These three study lake catchments have been part of a long-term monitoring program by the Ministry of the Environment, Conservation and Parks at the Dorset Environmental Science Centre for more than four decades. A mass-balance approach was used, meaning that microplastics entering and leaving the lake catchment were accounted for in order to determine how much accumulates in the study lakes. This approach incorporates inputs from the atmosphere and inflow streams and weighs these against losses to lake outflows and sediment. The results showed that the atmosphere had the highest daily rate of microplastics coming into the catchment (3.84 – 8.04 MP/m2/day) compared to the inflow streams (2.11-2.34 MP/m2/day). This suggests that atmospheric deposition is an important source of microplastics to remote regions, with 41-73% of the microplastic that fall from the atmosphere being retained in the terrestrial area surrounding the lake. On a daily basis, between ~1.5 million MP and 8.5 million MP are retained in the lake suggesting that lakes are a large storage area for microplastics. The quantity of microplastics lost to lake sediments is a small percent (7-17%) compared to the quantity of microplastics leaving the lake through the outflow, suggesting that lake sediments are a relatively small sink for microplastics. Fibres were the dominant microplastic shape identified in atmospheric deposition, lake water and inflow/outflow streams, with lake sediment having a higher proportion of fragments. This suggests that fragments may settle at a greater rate than fibres. Improving our understanding of microplastics in the environment is the first step towards mitigating the impacts of microplastics and will help guide the management of plastic pollution.
Bio
Brittany Welsh is a first year PhD student in Environmental and Life Sciences at Trent University. Her research focuses on understanding the sources and fate of microplastics in freshwater environments. For her M.Sc. Thesis, she examined the presence of microplastics in the atmosphere, inflow and outflow streams, lake water and sediment to determine the sources and fate of microplastics to remote headwater lake catchments. Brittany’s PhD research will focus on developing new tools that can be used to improve the collection of microplastics in air and water as well as examine the sources and transport processes of microplastics to watersheds (atmosphere, lake water, sediment, and soil) across an urban gradient.
MWC meetings are open to the public. Please contact info@muskokawatershed.org to get the Zoom details.