What Litter is Entering Toronto’s Outer Harbour Marina?

A preliminary look at what Seabins are collecting along Toronto’s waterfront.

This past August, PortsToronto installed two Seabins at Toronto’s Outer Harbour Marina and we visited them to count the litter they captured. This was done to help measure their effectiveness and better understand what litter is reaching our Great Lakes. Resembling underwater garbage cans, Seabins help clean the harbour by pumping water through a catch bag. This action removes, along with other contaminants, plastic litter greater than 2mm in length.

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Removing Seabin from harbour.

Although it was our first-time quantifying litter from Seabins, it wasn’t our first time counting and classifying trash. We’ve spent many hours over the past few years searching for plastic in an array of environmental samples. These experiences have taught us a lot, but one of the biggest takeaways is that plastic pollution is ubiquitous. With this in mind, we were prepared to spend the entire day counting; however, when we arrived at the marina, we were pleasantly surprised. Since we’ve both participated in community cleanups before, we expected to find large amounts of litter (as this was the trend for many cleanups in urban areas); however, upon arrival our presumption quickly changed. The water was clear and the docks were tidy… surely the Seabins wouldn’t have much to catch then, right?

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Size definitions for ‘big’ and ‘little’ plastics: big plastics were’ bigger than or equal to the size of a nickel’ and little plastics were ‘’between the size of a nickel- and nurdle’ (represented by orange arrow).

Turns out appearances can be deceiving. Half a day later, we’d only finished the easy part: removing plastics larger than a nickel (what we classified as “big plastics”). It would take days to count all the “little plastics” too (those smaller than a nickel but equal to or bigger than a nurdle, small pre-production pellets used in the production of plastic products). Because of this, we decided to subsample and extrapolate the results. After another half day and some quick calculations, the results were in: nearly 2000 pieces of plastic between the two bins. Amazingly, it had all accumulated in less than 24 hours.

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Breakdown of how litter was sorted and main results.

Much of this experience was surprising, from finding almost 2000 plastics in a seemingly clean environment to having a passersby ask us whether or not we’d found gold. (The answer, unfortunately, is still no). Overall, it was a rewarding learning experience, and a great chance to share our work with those at the marina. It was also a wonderful opportunity to learn more about how to mitigate plastic pollution – including microplastics. Together with other waste management systems, we feel Seabins are an effective form of technology to assist in protecting our bodies of water and are excited to see more innovative technology in the future.

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Preliminary results indicated a high amount of plastic fragments.

Written by Annissa Ho and Lara Werbowski, two HBSc students at U of T who are members of the Rochman Lab and U of T Trash Team.

 

How I spent my summer Vacation

A sampling of the unique ways some of our team spent their summer.

Summer is over and school is officially back in session, which means students are returning to the classroom and swapping stories about all the fun they got up to over the summer season. Tales of trips to the beach, vacations to exotic locations and new adventures in fine dining– so many stories to share! For the U of T Trash Team, we spent our summer vacation a bit differently. From exotic trips to study litter in Vietnam, many hours in the lab analyzing microplastic samples, to a variety of field work and outreach activities, we sure had quite the memorable summer. This is just a sample of what some of our team got up to.

Nick Tsui: Nick had the opportunity to wade (quite literally) into field work and meet with many groups (including industry, government, and academic stakeholders). His most memorable experience? Getting caught in 60mm+ rainfall doing fieldwork (without a raincoat!).

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Many new friends were made during Rachel’s time in Vietnam

Rachel Giles: Rachel joined Chelsea on a unique opportunity to visit Northern Vietnam and study litter and its impacts on mangroves in Vietnam’s Xuan Thuy National Park. There were many highlights on the trip, which included meeting lots of new friends, trying new and interesting local foods, and seeing mudskippers for the first time!

Jan Bikker: Jan spent her summer in the ABEL lab at McMaster as part of a collaborative study investigating the effects of microplastic exposure on fish behaviour. When not in the lab, she also got to help with fieldwork for two projects- one monitoring the population of the invasive round goby in Hamilton Harbour and the other looking at changes in the fish and zooplankton communities on a gradient away from wastewater treatment plants.

Lisa Erdle: Lisa spent time on Georgian Bay to investigate the effectiveness of washing machines filters at capturing microfibers. Nearly 100 volunteers in Parry Sound installed washing machine filters in their homes as part of a pilot program with U of T and Georgian Bay Forever.

Arielle Earn and Ludovic Hermabessiere: Arielle and Ludovic spent a day in the Rouge Valley during the 2019 Eco Exploration Event talking to many new people about microplastics. They were able to explore some of the beautiful conservation land and even spent time doing a small cleanup of the area, finding a straw, a coffee cup and many fragments of plastic surrounding the nearby stream. They also got to hear many stories from the people they talked to – including one about the folklore surrounding Bigfoot’s existence in Rouge Valley!

Alice (Xia) Zhu: Alice spent her summer analyzing data on microplastics from San Francisco Bay. Many different shapes and polymer types of microplastics were found in sediment, fish, surface water, stormwater, and wastewater from San Francisco Bay and Alice analyzed patterns in their characteristics to help determine the sources of microplastics to The Bay. She had a great time learning new ecological statistics and R functions. Fun fact: over 300 samples were analyzed in total, including 152 fish!

Ludovic Hermabessiere: Ludovic recently moved here from France and spent his first few months in Canada working at the Rochman lab with Raman spectroscopy. His work will help to analyze and identify potential plastic particles faster. Ludovic is also preparing the arrival of a new equipment to identify smaller plastic particles.

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Kennedy and Hayley enjoyed the field station life while spending time in the Experimental Lakes Area in Northwestern Ontario.

Kennedy Bucci and Hayley McIlwraith: This summer, Kennedy and Hayley left the traditional lab for a natural laboratory at the Experimental Lakes Area in Northwestern Ontario. They collected surface water, sediment, and air samples to look for microplastics in remote boreal lakes. They enjoyed life at the field station, canoeing and portaging to their sampling sites, and returning to camp in the evening for swimming, bonfires, and delicious meals prepared by the camp chefs.

Bonnie Hamilton: Bonnie spent a portion of her summer in the Canadian High Arctic to evaluate contaminant concentrations in Arctic char—a cold adapted Salmonid. This year, her trip was spent off-grid on the tundra at the mouth of the Lachlan River 150km west of Cambridge Bay. Some of the trip highlights included working with collaborators at DFO, UBC and the Arctic Research Foundation, Arctic wolf and grizzly sightings and sampling these beautiful fish!

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Bonnie (and arctic char), during her time in the Canadian High Arctic.

Annissa Ho and Lara Werbowksi: Lara and Annissa got out of the lab and spent a day at the Outer Harbour Marina counting and categorizing trash collected by Seabins. Despite the smell, the activity attracted some passers-by and allowed Lara and Annissa to share their new knowledge of the trash in the marina! Overall, it was a great experience and the results were fascinating. Their favourite finding? One bin captured more than 1000 pieces of plastic in less than 24 hours!

We can’t wait to see what our Trash Team gets up to this fall and winter season, likely it will be filled with more tales of field work, outreach events, and travels to see plastic pollution abroad.

Written by Susan Debreceni, Outreach Assistant for the U of T Trash Team.

Mangroves are Vital to Vietnam’s Coastal Communities

A case study of plastic pollution and ecosystem health in Xuân Thủy National Park.

“Rice bag fragments: 2. Food wrappers: 7.”

This was our rhythm while counting litter along the northern coastline of Vietnam. For four days, we maneuvered through what seemed like a video game adventure—dodging obstacles while onboard a boat, trudging through mudflats and combing through the thickest of forests. I was with Dr. Chelsea Rochman and Rachel Giles from the University of Toronto, representing Ocean Conservancy on a research expedition in the beautiful mangrove forests of Xuân Thủy National Park, Vietnam. We were there to assess how the biodiversity of the environment and the livelihoods of nearby coastal communities are affected by plastic pollution.

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Mr. Nguyễn Viết Cách, former director of Xuân Thủy National Park, points out a flower known as hoa bần on a mangrove apple tree. © Cindy Nguyen

Xuân Thủy National Park sits at the mouth of the Sông Hồng, or the Red River: a broader estuary ecosystem which supports mangroves, intertidal habitats and feeding grounds for important migratory bird species. The park, Southeast Asia’s first Ramsar Site, falls along the coast of the East Sea and is recognized as a fundamental site for conservation because of the ecological functions it performs as a wetland. Not only does it serve as a rich habitat for a variety of shrimp, crab, fish, razor shells and oysters, and supports numerous rare and endangered species, but it also provides economic prospects for the five coastal communes of Giao Thủy, a rural district in Nam Định Province. Here, the community is comprised of small-scale fishermen and farmers in aquaculture and agriculture, who contribute collectively to a network of food cultivation.

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Local farmers of Giao Thủy invite Cindy to assist in weighing fresh clams. © Chelsea Rochman

With trash flowing into the estuary from the Red River and marine debris washing up from the ocean, the park is becoming increasingly vulnerable to plastic pollution. Potential threats to the park include microplastics coming in from ocean currents, a growing human population and burgeoning tourism industry. Previous research on the park has also identified various challenges for the sustainable management of its valuable resources.

For these reasons, the Centre for Marinelife Conservation and Community Development (MCD) has raised concerns about the state of litter in the park. MCD is a leading Vietnamese nongovernmental nonprofit organization with extensive work within the Red River Delta, and Ocean Conservancy is excited to partner with an organization that has demonstrated expertise and success in bringing together local and national government, the private sector and other NGOs. We collaborated with MCD and also the Vietnam Administration of Seas and Islands (VASI) to conduct a baseline assessment of the sources, fate, and effects of marine debris, including microplastics, in this region.

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Rachel and Chelsea standing on debris at research site © Cindy Nguyen

Fortunately for us, we had sunshine and only light rain during the week of field research. The on-the-ground work involved counting and categorizing all the litter we found within our research sites, as well as taking samples of sediment to measure microplastics. To begin understanding where debris may be coming from, we had selected key locations along the shorelines and tidal flats of the estuary and mangrove forest, at the mouth of the river and upstream along the Red River. We also counted crab holes at each site and measured the canopy cover and diameter of mangrove tree trunks as potential indicators of how waste might be affecting flora and fauna in the park.

What were some highlights in our field research? Besides the fact that we were located in this amazing corner of the world, we enjoyed the learning and sharing of information between our teams. When in the field, we paired up in working teams of two—Chelsea with Nguyễn Văn Công (MCD), myself with Ngô Thị Ngọc (MCD) and Rachel with Mai Kiên Định (VASI). Ocean Conservancy hoped to build capacity in MCD and VASI by transferring our science and methodology on how we research marine debris. Likewise, Công and Ngọc gave us insight into the debris we found and explained why some items were more common than others. Định, who is local to the province, shared his understanding of the land and lifestyle of farmers in the area. After long hours out in the field, we continued the conversations at nearby restaurants where we cooled off and dined on fresh seafood—including farm-raised clams, freshwater fish and jellyfish.

What were we not prepared for? Finding ourselves knee-deep in mud, amongst clams and sort-of-friendly crabs. Stumbling upon a graveyard of dead mangrove trees, tangled in plastic bags and fish netting. On one site along the shoreline, spiders hanging out tree branches joined us as we counted hundreds of pieces of foam. Thankfully, park rangers from Xuân Thủy National Park helped us navigate by boat, foot and car to access all of our sites. Needless to say, the research was very successful thanks to everyone’s eager helping hands and enthusiastic spirit in the field!

What were some of our findings? Marine debris was found across all of the 19 locations we surveyed. The five most common items were plastic food wrappers, plastic bags, fabric pieces and pieces of plastic rope and fishing nets. Overall, increased amounts of marine debris led to a decrease in the health of the ecosystem, although this was only significant for the negative relationship between quantity of marine debris and health of the mangrove trees. The results definitely show a lot of potential for future work to follow up on these trends.

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Rachel, Định, and Ngọc counting litter on one of the research sites. © Cindy Nguyen

We appreciate that MCD is first and foremost committed to making this work and learnings accessible to the public. In a conversation that Công and Ngọc led with Giao Thiện commune, we learned from fishermen about the ways in which pollution leads to the degradation of their land and harms not only people, but the ecosystem as a whole. I especially appreciated that everyone at MCD was eager to converse with me in Vietnamese as they answered my questions. As a Vietnamese-American only somewhat proficient in the language, I felt very much empowered to practice the vocabulary of environmental conservation in my mother tongue.

Ocean Conservancy hopes that this case study will inform local stakeholders to determine specific solutions addressing the vulnerability of Xuân Thủy National Park. We also envision that future research will advise national stakeholders as they develop a long-term strategy for Vietnam’s coastal wetlands. While there are still major gaps in the research that make it difficult to track environmental stressors and ongoing changes within the park, Vietnam is taking major steps to protect its wildlife and coastal communities.

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The entire team – OC, MCD, VASI, and Xuân Thủy National Park. © Rachel Giles

Written by Cindy Nguyen (Roger Airliner Young Marine Conservation Fellow) in collaboration with Dr. Chelsea Rochman, assistant professor at University of Toronto (UofT), Rachel Giles, graduate student at UofT, and Nguyễn Văn Công, representative at Centre for Marinelife Conservation and Community Development (MCD).

To Flush or Not to Flush – That is the Question

Ever heard of “demon snowballs”? Likely not, and it is probably putting images in your head of something cold and wet. Well, these demon snowballs are generally wet – but are not formed by snow and are not wonderfully white. These “snowballs” are wet wipes, and are called demon snowballs by wastewater treatment plant operators because of the way they get stuck in wastewater infrastructure. How is this relevant to ocean lovers? Wet wipes are a common type of marine debris – entering the environment via untreated and treated wastewater.

Although you may throw your wet wipes in the trash can – which is the best thing to do with them – many wet wipes are marketed as “flushable.” Flushable, or non-flushable, wet wipes are manufactured as non-woven sheets of natural and manmade fibres – including cellulosic materials like rayon and/or plastics (Munoz et al. 2018). Wet wipes usually have a high wet-strength, because synthetic fibers retain their form, shape, and strength in a moist state. Maintaining their form, and being strong, are desired properties for wipe manufactures so the product will not fall apart while you use it.

When flushed, wet wipes enter the sewer systems, where they are assumed to move along with wastewater to treatment plants. However, their transport depends on various factors such as pipe diameter and slope, flow rate and velocity, plus the amount of product discharge.

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Wet wipes at a sewer outflow into creek

If a significant amount of flushable wipes are discharged into a sewer system over a short period of time (a few hours), they will accumulate in drains, forming large “white” balls (a.k.a., demon snowballs), and lead to potential sewer backups. Holiday weekends, such as those in summer where people congregate, are an example of times when the amount and frequency of discharge at a single location may increase due to families and friends visiting each other. Likely not something you think about when you convene for a family weekend at the beach!

When we flush our products down the toilet, it absorbs and blends with other waste we send via our households such as food waste, fat, oil and grease (called FOG by plant operators), shampoo, human hair, and cosmetics. When flow is intermittent and low as our household plumbing, flushable wipes settle in our sewer pipes, accumulate over time, and can cause back-ups followed by sewer overflows. At treatment facilities, wipes clog and damage wastewater equipment such as screens, pumps, grinders, mixers, and sensors that require complete replacement or extensive repairs – hence demon snowballs.

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Example of pump blockage from flushed wet wipes

As examples, in England and Wales, approximately 4,000 cases of pipe blockages and property flooding are reported each year (Jeyapalan 2017). In the USA, 400,000 basement backups and 50,000 sewer overflows are documented per year (USEPA 2001). The City of Toronto, Ontario has approximately 10,000 calls a year for reported blockages. Unfortunately, wastewater utilities from around the world have been reporting that wipes are responsible for most pipe blockages and pump clogs in sewer networks. These reports have been published as a series of articles in various languages, and in well-known newspapers such as New York Times (Caron, 2018), The Guardian (UK), and the National Post (Canada).

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Barry Orr holds a mass of wet wipes from a pump station

Consumers assume that “flushable” products must have been tested rigorously for their compatibility with household plumbing and sewer systems. In contrast, there is actually no standard definition of what is flushable, and no standard method to assess flushability. Wastewater engineers are trying to work with governments to help define technical characteristics of flushable products, so that we can clearly differentiate the products that are truly “flushable” from those that are not.

For now, to keep our plumbing “snowball free”, we must not treat wet wipes – whether they say “flushable” or not – like toilet paper. Their size, strength and material composition prevent them from breaking down in wastewater systems, and even if they break down, they may contribute to microplastic pollution in the environment. The bottom line – stop flushing wipes.

Blog written by Barry Orr, spokesperson for Municipal Enforcement Sewer Use Group (MESUG), of Ontario and Faith Karadagli, Associate Professor of Envrionmental Engingeering at Sakarya University, Turkey.

The Decade of Plastic Pollution & Canada’s Leadership

Canada’s recent announcement is a big step forward, but there is still more work to be done

One decade ago, I hopped aboard a research vessel with the Scripps Institution of Oceanography and took my first trip to the North Pacific Garbage Patch. At this time, we had heard about large concentrations of plastics in the middle of the ocean, and about mammals and birds being entangled by large plastic nets and line. What we really understood about plastic pollution ten years ago was just the tip of the iceberg.

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© SCRIPPS INSTITUTION OF OCEANOGRAPHY

As we boarded the ship, we pictured we’d soon be arriving to a large mass of floating debris far from human civilization. We pictured fishing nets, buoys, bags and other large items that could be cleaned up. When we arrived, we saw what the garbage patches really look like. When plastic waste is littered and finds its way to our ocean or even the Great Lakes, it travels with the currents as it’s beaten down by the sun, wind and waves. The plastic that makes its final stop in the garbage patches, 1000s of km out to sea, are mostly small bits of microplastics—the size of a pencil eraser and smaller. Off the bow of the ship, on a sunny and calm afternoon, I saw bits of plastic confetti as far as my eyes could see—making up not a garbage patch you could clean up, but a soup of small plastic debris that could infiltrate every level of the marine food web.

This research expedition, ten years ago, was the beginning of my career quantifying, characterizing and increasing our understanding about the impacts of microplastics in aquatic ecosystems. Today, I no longer spend my time researching plastic pollution in the ocean garbage patches far from civilization; I work with an amazing group of students and collaborators and together we research plastic pollution in rivers, bays, estuaries and lakes—in Canada, the U.S. and abroad. We have never been to a study site where we have not found microplastics in our samples. In fact, some samples have so many pieces we have more than 15 students working on one project.

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Keenan Munno, Tina Wu, Chelsea Rochman, Cassandra Sherlock, and Annissa Ho in the Rochman Lab collaborating on a project to quantify microplastics in the San Francisco Bay. © CAFETERIA CULTURE

This decade, I have been incredibly inspired by the positive change I see around me and the motivation I see by governments around the world to mitigate plastic pollution. This week, I was proud to stand on the shores of Lake Ontario, where we’ve found microplastics in surface waters, sediments, local fish and in drinking water, with the Canadian Minister of the Environment Catherine McKenna and Member of Parliament Julie Dabrusin for an announcement about how Canada will continue to take leadership on the issue.

When I started working on this issue, over one decade ago, it received very little attention from fellow scientists, policy-makers and the public. Today, I am pleasantly shocked everyday by how many people are listening and willing to come together to mitigate the issue.

The announcements made this week by the Canadian Government are a very important step forward, and I’ve been very impressed by the leadership from the Canadian government at working to tackle this issue. There is no silver bullet solution to plastic pollution, and we need solutions that span clean up, reductions in waste and improved materials management. The government has committed to a holistic approach that includes these elements, including research to inform the most effective mitigation strategies.

For this reason, I was thrilled to be invited to share my story and my thoughts on the issue as Minister McKenna made the announcement in Toronto. It was a great opportunity to publicly acknowledge the work Canada has done on this issue including the online portal, the fund for international collaboration, the Ocean Plastics Charter and the support for continued and improved research.

While this is a huge step forward, all should recognize that this is only the beginning and that the work starts here. Everyone across the world has work to do to solve this global issue. As a citizen, we can refuse items that cannot be sustainably managed via reuse or recycling,  reduce the waste we produce and become more waste literate. We can also share our concern with others and write letters to government asking for support.

I intend to continue to work tirelessly on this issue via research through my laboratory at the University of Toronto and through our outreach program—the UofT Trash Team. I spent my last ten years producing data that could inform policy. I am comforted knowing that over the next ten years, the government and all of you will be working right along with me using this new information to inform positive change. This truly is the decade of plastic pollution, and I hope that ten years from now we can all look back on the work we did together and boast about a measurable reduction in the amount of plastic that becomes waste and is littered on the coastlines of Canada and around the world.

Written by Dr. Chelsea Rochman, Assistant Professor at University of Toronto and Scientific Advisor to Ocean Conservancy.

Keeping Canada’s Most Urbanized Watershed Clean

Second Annual “Cleanup the Don” a success

On May 5th, 2019, more than 100 dedicated volunteers grabbed bags to participate in the University of Toronto’s Trash Team’s 2nd Annual Cleanup the Don, a collaboration with the Toronto Region Conservation Authority (TRCA) and Ocean Conservancy’s International Coastal Cleanup (ICC) coordinator in Canada, the Great Canadian Shoreline Cleanup. In conjunction with the TRCA’s annual Paddle the Don event, Cleanup the Don brought members of the community down to the Don River to traverse and conserve one of Toronto’s most important watersheds.

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Trash Team member Sam explores the Don River by paddle © UNIVERSITY OF TORONTO

Stretching nearly 24 miles and spanning more than 88,000 acres, the Don River is one of the largest rivers entering Lake Ontario. The Don River Valley is a popular area for recreational activities, including biking, running, fishing and canoeing. The area is also home to a wide variety of wildlife, including some endangered species like the Redside dace fish and American chestnut tree.

Habitat loss and chemical pollution are major threats to urbanized watersheds like the Don River. Estimates from our most recent University of Toronto Trash Team survey of the river suggest it is also an important route for hundreds of pounds of plastic litter from urbanized areas (like the Greater Toronto Area) to enter the Great Lakes every year.

This year for Cleanup the Don, 107 volunteers spread out across five sites from E.T. Seton Park to Corktown Commons, a six-mile stretch. In all, we removed approximately 550 pounds of plastic litter from the shorelines.

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Top 6 items found during this year’s Cleanup the Don. © UNIVERSITY OF TORONTO

The top six trash items closely tracked what volunteers find during the ICC every year, including cigarette butts (25%), plastic food wrappers (13%), plastic bags and other single-use plastics. We were also surprised to find some unusual items, including a tent and VHS tape cover.

A selection of litter collected during this cleanup was also used to create a mural depicting the Don River Valley. Repurposing litter into artwork can be a great way to raise awareness about how plastic pollution affects your local environment.

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Litter collected during the cleanup was used to create a mural depicting the Don River Valley. © UNIVERSITY OF TORONTO

Since most plastic pollution comes from land-based sources, understanding the sources of plastics in the environment can help us “turn off the tap” or stop the flow of plastics to local waterways like the Don River. Single-use plastic restrictions (such as plastic bag bans) and improvements in waste management can help reduce the number of these items that end up in the environment. Below are five simple actions that individuals can make to help keep plastic from entering the Don River watershed and other waterways:

  1. Reduce your use of single-use plastics! Opt for more eco-friendly alternatives like reusable shopping bags and metal/glass straws.
  2. Clean up your local watershed. Join a local cleanup or start your own. Join Ocean Conservancy on the world’s largest single-day volunteer effort on behalf of the ocean, the International Coastal Cleanup. This year it’s September 21st, 2019. Tips on how to organize a cleanup in your area are available through the Great Canadian Shoreline Cleanup website.
  3. Know your bins! Be aware of which items go in green, black and blue bins. For guidance in the City of Toronto, check out the Waste Wizard app!
  4. Support legislative or community action to reduce single-use plastics and improve waste management in your area.
  5. Educate friends and family about the plastic pollution problem.
Written by Trash Team members Sam Athey, Bonnie Hamilton and Dr. Chelsea Rochman.

Plastic Pollution is Chemical Pollution

How preventing and removing plastic debris mitigates chemical pollution in our oceans

Turtles tangled in fishing nets, whales washed ashore with stomachs full of plastic bags. These are images we, unfortunately, see far too often. But what about the threats you cannot see? Plastic debris is not just a physical threat to marine life, it’s a chemical threat too.

Once in the marine environment, plastics can absorb chemical pollutants from surrounding waters and transport them great distances as they move around with ocean currents. When animals eat plastic, these chemical pollutants can leach into their stomachs, causing toxic effects. Many of these chemicals have been banned from production due to concerns about human and environmental health. However, some are so persistent in the environment that they are still found today.

Plastic products also contain chemical additives such as flame retardants, UV stabilisers and colorants which are added to the plastics during manufacturing. In our ocean, these chemical additives can leach into surrounding waters—posing another potential chemical threat to marine life.

In a recently published paper, we estimated the amount of chemicals that enter the ocean within common single-use plastic items and estimated the amount of chemical pollutants that can be removed from the environment via cleanups.

2018-07-20 14.49.34We looked at some of the most common plastic items found on beaches during the International Coastal Cleanup: beverage bottles, bottle caps, styrofoam foodand drink containers, cutlery, grocery bags, straws/stirrers and food wrappers. Using International Coastal Cleanup data, the average weight of each item, and estimates of mismanaged plastic waste in 2015, we calculated the total weight of each item that entered the oceans in 2015. We then used the percent weight of chemical additives in each item to estimate the mass of chemicals that entered the ocean as a consequence of this plastic debris.

We estimate that combined, these seven plastic items contribute more than 87,000 metric tons of plastic debris to our oceans and carry with them 190 metric tons of 20 different chemical additives. If plastic pollution continues to increase, this value could almost double to 370 metric tons of additives by 2025. This might not sound like very much, but these seven items account for only about 1% of the estimated 8 million metric tons of plastic entering the oceans every year!

Furthermore, we estimated how plastic cleanups contribute to chemical cleanup by removing those absorbed chemical pollutants. For this, we compared coastal and open ocean locations using Hong Kong and Hawaii as coastal case studies and the North Pacific and South Atlantic gyres as open ocean case studies. Here, we focused on Polychlorinated biphenyls (PCBs) because they are commonly found in plastic debris, despite having been banned for decades.

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© HANNAH DE FROND

To estimate total chemical load on plastics in each location, we multiplied the mass of microplastics (g/m2) found in each area by the mass of PCBs found on microplastics (ng/g) in each area. Our results showed that chemical cleanup is more effective on shorelines compared to the open ocean, removing 85,000 times more PCBs in a stretch of coastline in Hong Kong than the same size area of the North Pacific gyre. This might come as a shock, particularly as the gyres are well known to contain large amounts of plastic debris, however, the amount of microplastic per square meter is generally much greater on the shoreline. Although the concentration of PCBs might be high in some open ocean locations, the important factor is how much plastic can be removed per unit area. The more plastic removed, the more chemical removed.

Thus, if we can prevent plastic from entering the environment and cleanup what is already there, we can also mitigate chemical pollution. This reiterates the value of reducing our plastic footprint and participating in coastal cleanups. Cleanup of plastic pollution goes beyond what the eye can see. Cleanup of plastic pollution is also cleanup of chemical pollution!