Transport and mixing of particles in stratified environmental flows.

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Canada borders the world's largest inland lake system, and has the world's longest ocean coastline. The successful environmental management of these important aquatic systems requires a clear understanding of how sediment, nutrients, and chemicals are diluted and transported from high-density population areas to sensitive ecological habitats. In this grant, we focus on the underlying physical processes of three basic aspects of particle transport: where sediment accumulates on the ocean floor, how sediments from rivers fill in harbours and estuaries, and the spread of micro-plastics, which hurt fish in our lakes. My research program studies these processes with laboratory experiments, mathematical modeling, and field studies. In the first aim, we will develop new conceptual models for the evolution of some of the largest sediment deposits on the ocean floor and determine how the shape of these large sediment deposits is influenced by the speed of the ocean currents. In the second aim, we will address the situation where a sediment-laden flow of a river enters into a stratified lake or the coastal ocean and it is important to know how fast the sediment settles, as this determines the scale over which sediments deposits form. In the third aim, we will establish how wind-driven turbulence and currents control the vertical and horizontal spread of buoyant micro-plastic particles in the Great Lakes, which will be an important step in helping government agencies manage the environmental impacts of this form of pollution. Overall, my internationally-recognized NSERC program of research is directed at understanding the physical processes that control transport and mixing of particles, chemicals and biology in stratified lakes and the coastal ocean. To keep my research rooted in urgent, practical concerns, I collaborate with environmental agencies at the federal, provincial and municipal levels. These partnerships have also allowed me to leverage additional funds for a larger program of fieldwork, and to ensure that our new science is used by relevant authorities to help formulate their management decisions. The proposed research will advance our understanding of environmental fluid dynamics relevant to Canada's socioeconomic and environmental needs.