Global Water Futures HQP shares her research on legacy phosphorus in Lake Erie

Monday, August 31, 2020

Since the 1960s, eutrophication has been a critical problem in Lake Erie. High phosphorus concentrations in lake water are considered to be one of the major drivers that causes eutrophication leading to an overgrowth of algae. After the restriction of phosphorus use in household products, and upgrades of wastewater treatment plants, eutrophication was absent in the lake from 1980 to the mid-1990s. However, in the past ten years, its severity has increased significantly,  despite numerous attempts to reduce phosphorus loadings and improve the water quality by adopting various conservation practices and policies. This is what motivated Lamisa Malik, PhD student in the Department of Civil and Environmental Engineering, to study the persistent eutrophication problem in Lake Erie.

“It is believed that legacy phosphorus that has accumulated in soils, groundwater, and wetlands from past applications of manure and fertilizer is responsible for delayed recovery from water quality impairment,” said Malik. “The continuous release from legacy pools has left us to question the importance of the contribution of these pools in present phosphorus loading, and how long the impacts of legacy phosphorus will persist in the future.”

Working with her supervisor, Water Institute member and professor in Waterloo’s Departments of Earth and Environmental Sciences and Civil and Environmental Engineering Nandita Basu, Malik discovered that past land-use practices have a significant impact on phosphorus input to the waterbody.

“We found that legacy phosphorus stored in the soil in the watersheds of Lake Erie, may take several decades to travel before it reaches the stream and shows an increase in stream-phosphorus concentration,” said Malik. “We also discovered that the US and Canadian watersheds of the Lake Erie basin show different phosphorus input and export trajectories, which may require adaptation of different strategies to mitigate the problem.”

To reduce nutrient pollution and re-eutrophication in Lake Erie, a bi-national plan has been adopted by the US and Canada to reduce phosphorus loadings to the lake by 40% by 2025 (IJC, 2014). Malik, with her research group, has been working to develop a Lake Erie scale model that will generate future scenarios based on phosphorus mass balance and historical land-use changes to evaluate how achievable the load-reduction goal is.

“Working with other researchers from different disciplines has been a very beneficial part of our research so far,” said Malik. “Understanding the perspectives of those outside of my field has strengthened my research and encouraged me to incorporate knowledge mobilization activities into my research plan to ensure my results are shared with, planners and policymakers to help inform better decision making.”

Learn more about the Lake Futures research project.

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