Over this past summer, while you were walking along the waterfront, taking a ferry to Centre Island, or swimming at Cherry Beach you may have encountered bright orange water bottles drifting aimlessly through Toronto Harbour, but these water bottles weren’t litter – they were research! We, the U of T Trash Team, launched the Tagging Trash project in collaboration with PortsToronto, Toronto Region Conservation Authority, Ontario Ministry of the Environment, Conservation and Parks, and University of Toronto Scarborough, to learn how plastic litter travels in our harbour. Throughout April to August, we released orange GPS-tracked bottles from various points across the Toronto Waterfront, Harbour, and Islands. You may be asking, “Why? Isn’t this making plastic pollution worse?” The answer is, we are actually working towards solving our plastic problem. Plastic pollution in our waters causes harm to wildlife and tarnishes the beauty of our lake. To address this problem we first need to understand where litter comes from, where it travels, and how long it takes for litter to reach its final destination. Through our research, we were able to collect valuable data that reveals the way floating plastic litter travels in our harbour and where we need to place cleanup technologies like Seabins!
So, HOW did we do this?
Step 1: Designing the tracker bottles
Why water bottles? Plastic bottles are a common litter item found along shorelines. They are also large and buoyant, which makes them the perfect housing for our Globalstar IoT Satellite Trackers. We also needed to ensure that our GPS trackers were always facing the sky to provide us with the most accurate GPS coordinates – and these bottles were an ideal shape for adding the necessary weight to act as ballast and keep the trackers facing skyward.
To try to prevent people from mistaking our bottles as trash (more on this below), we posted signs about our project and labelled each bottle with clear messaging that they were for research with a QR code linked to our website. We also publicized our Tagging Trash project through social media and the local news.
Step 2: Selecting deployment locations
To get realistic information regarding how litter moves in the harbour, we released bottles from areas that are likely sources of plastic litter based on Visual Audits conducted in the summer of 2020, visitor hotspots, and scientific studies of water movement within the harbour. Overall, we picked 13 locations, ranging from Bathurst Quay, Keating Channel, the tip of Tommy Thompson Park, and the Toronto Islands.
The Tagging Trash initial (yellow) and final (magenta) positions in Toronto Harbour (Google Earth 220.127.116.1148 (2021) Toronto Harbour, 43°38’20”N, 79°22’20”W).
Step 3: Tracking where the bottles went
After observing how the bottles traveled over a period of 4 months, we learned that litter gets into the nooks and crannies of our waterfront. Anywhere we found our GPS-tracked bottles, there were hundreds of pieces of litter. Our bottles also revealed some really interesting movement patterns.
Having a nice view depends on where you look, eh? Bottle floating in and out of the Pirates life dock at Bathurst Quay.
Most of our bottles quickly travelled through Toronto Harbour for about one kilometer before becoming trapped or stranded on shore within a day of being deployed. These bottles, which have similar trends in travel, were typically recovered from sheltered areas like slips, bays, and under piers, docks, and boardwalks. This information lets us and policy makers know that most of the trash in the harbour likely comes from Toronto. Litter which makes its way into the middle of the harbour tends to move with the prevailing winds toward the Keating Channel and the shipping channel. This is concerning because we suspect that plastics can be hit by boats and broken into smaller pieces of plastics, expediting the formation of microplastics. More trash capture devices and local trash cans with lids will reduce the litter in Toronto Harbour and prevent the formation of microplastics.
Above is a wind rose which shows the directions from which wind travels in Toronto Harbour. The longer bars indicate that winds blow more often while the colour corresponds to wind speeds. For the summer of 2021, the prevailing winds blew from the west/west-southwest nearly 25% of the time and there were several storms that brought in strong winds from the east.The observed westerly prevailing winds help keep litter in Toronto Harbour.
Bottles became trapped under city infrastructure or stranded onshore once they reached areas sheltered from the wind. Occasionally, large waves from storms would strand bottles on land and prevent them from travelling within the harbour. Some bottles, however, were a little more adventurous.
While most of our bottles stayed in the harbour, the ones that escaped the harbour left through the Western Gap more often than the Eastern Gap, and would soon beach. To test if trash from Toronto’s popular beaches could travel farther into Lake Ontario, bottle “John Tory”, from deployment 3, was deployed from the southern end of Center Island. During its 300 km journey, it spiraled its way to Ajax. The spiraling path demonstrates the Coriolis effect from Earth’s rotation. A more adventurous bottle, Onitariio, was released from the tip of Tommy Thompson Park to test if litter east of the harbour is likely to travel into the harbour. Remarkably, this bottle travelled across Lake Ontario for 300 km until its batteries ran out of charge near Rochester, NY.
Bottle “Onitariio” (yellow) from our April test-deployment was released from Tommy Thompson Park and had travelled past Rochester, New York. Bottle “John Tory” (pink) from our third deployment had travelled from Center Island and beached in Ajax.
Some bottles weren’t big on travelling and were retrieved only a few dozen meters from their deployment locations. They became stuck under the boardwalks near Harbour Square Park West and were, unfortunately, not reachable by powerboat; we had to retrieve these trackers by kayak! While retrieving them, we found hundreds of pieces of litter from clothing, boating gear, food containers, and many microplastics. These hard to reach areas could use passive trash capture devices (like Seabins) to make litter collection more feasible.
We observed several of our bottles travelling up into the Keating channel, and past the floating boom at the mouth of the Don River, which had been installed to prevent trash from flowing down the Don River and into Toronto Harbour. This movement surprised us because we didn’t expect our bottles to travel against the water current, but we later discovered that the winds were strong enough to push our bottles upstream. This information suggests the need to improve the effectiveness of “leaky” booms.
Other bottles that surprised us were those that ended up in garbage cans, despite our outreach attempts. This made for some interesting fieldwork; we found ourselves digging through garbage cans like raccoons when searching for our bottles. Although losing trackers to the garbage was frustrating at times, it showed that Torontonians care about the environment and feel a responsibility to keep their waters clean and plastic-free. We also saw, in real-time, the pathway our litter takes once thrown away – it heads to our city landfill located in London, Ontario!
We rescued some of our tracker bottles from the trash, can you spot one in this trash bin?
Step 4: Analyzing our findings
Overall, we had a ton of fun and learned a lot about how litter moves within our waterfront. We found that most of our litter likely stays in our own backyard. With the exception of a few sneaky bottles, most quickly accumulated in nearby sheltered slips, piers and embayments. Patricia Semcesen continues to work on this project and analyze our data which she will use to develop a hydrodynamic model that will help understand and predict the transport of plastic litter in Toronto Harbour.
Once the hydrodynamic model is developed, its results will inform where future trash captures devices should be placed to prevent litter from escaping into Lake Ontario. This information will also help in improving waste-management infrastructure, and encourage environmentally-friendly initiatives to reduce plastic litter locally, like bring-your-own reusable container and cutlery discounts. It can also tell us where regular cleanups should be organized to pick up trash from hard to reach places (like beneath boardwalks and docks) where trash capture devices can’t be placed. Along with collecting valuable data, we also found the Tagging Trash project a great tool for outreach and communication surrounding waste literacy both locally and globally. We hope to inspire groups across the world to initiate their own projects to better understand the fate of plastics in their waterways.
Written by Cassandra Sherlock (top), Former Community Outreach and Research Specialist at the U of T Trash Team, and Patricia Semcesen (bottom), Environmental Science PhD student at the University of Toronto, Scarborough.
We would like to thank everyone who assisted in making this project a success which includes our U of T Trash Team volunteers: Lisa Erdle, Brendan Carberry, Emily Darling, Madeline Milne, Ludovic Hermabessiere, Rachel Giles, Hayley McIlwraith, Su’aad Juman-Yassin, and Ariba Afaq, from GlobalStar Martin Jefferson, from TRCA, Laura Salazar, Matthew Fraschetti, Kirstin Pautler, Samuel Burr, Mark Wilush, Connor Hill, Brynn Coey, Brian Graham and Angela Wallace, from PortsToronto, Micheal David, Chris Sawicki and Jessica Pellerin, from MECP Bogdan Hlevca, from U of T, Matthew Wells, Chelsea Rochman, Rafaela F. Gutierrez and Susan Debreceni. We’d also like to thank our funders: Environment and Climate Change Canada and National Geographic.