Microplastics

Microplastics are very small plastic pieces found in the environment that can have negative impacts on rivers, lakes, oceans, fish and other wildlife. Some microplastics were produced specifically for use in consumer and industrial applications while others originated from larger plastic products (e.g., plastic drinking bottles) that have fragmented from weathering outside. Still others are small bits of plastic, such as shavings, created during the manufacturing (cutting, drilling, machining) of larger plastic products.

Once in the environment, microplastics do not remain stationary (due to their small size, buoyancy and durability), being moved by wind and water from land to rivers and lakes and eventually to the oceans. This means that even plastic and microplastic in Lake Simcoe and its watershed could eventually end up in the ocean!

Recent concern around the potential ecological impacts of microplastics has led to regulations to eliminate their use in personal care products. This means that the inclusion of microbeads in the ingredients of cosmetics (such as in some skin cleansers) will be fully prohibited in Canada soon. Furthermore, government agencies have initiated programs that address general plastic pollution.

Researchers are working to understand more about the sources of plastics to the environment, the extent of pollution in water bodies and the risks to living things. Studies have been carried-out in the Great Lakes to learn more about microplastics and research is currently underway in Lake Simcoe as well.

What are microplastics?

Over the last ~15 years, microplastic litter has emerged as an environmental concern in marine, freshwater and terrestrial ecosystems in Canada and globally (Anderson et al., 2016; Eriksen et al., 2014; Machado et al., 2017). Microplastics are small but potentially harmful plastic particles that can have negative impacts on lakes, rivers, oceans, fish and other wildlife. Researchers are working to understand the extent of pollution and risks, including predictions of future microplastic abundance, for both aquatic and terrestrial ecosystems (Anderson et al., 2017; Helm, 2017; Ivar do Sul and Costa, 2014).

Microplastics are commonly defined as fragments of plastic that are smaller than 5 mm in any dimension, though there is significant debate on the topic of size classification. There are two types of microplastics commonly found in aquatic systems, referred to as primary and secondary.

Primary microplastics are those that were produced “as they are” for use in a wide variety of consumer and industrial applications. Microbeads are an example of primary microplastics that have a number of uses, including as production pellets in the manufacturing of plastic products (such as plastic toys) and also as resin beads for ion exchange in water purification and softening techniques and for some medical and industrial purposes (Ballent et al., 2016). Microbeads have also been used in personal care products, as cleansing or exfoliating agents in cosmetics, soaps or toothpaste, and do not dissolve after they are rinsed down the drain [Ministry of the Environment and Climate Change (MOECC), 2016].

Secondary microplastics are those that originate from larger plastic and other synthetic materials that get broken down by weathering processes (e.g., UV degradation), wear-and-tear (e.g., tire wear during driving), or during manufacturing (e.g., shavings or abraded debris; MSFD Technical Subgroup on Marine Litter, 2013; Anderson et al., 2017; Ballent et al., 2016). Secondary microplastics include fragments (originating from the degradation of consumer litter, for example), lines and fibre (from rope, netting, cigarette butts or clothing during laundering), foam (from packaging) and film (from plastic bags and wrappers).

Mobility and fate of microplastics in the environment

Plastics encompass a diverse set of petroleum-based synthetic polymers with versatility that makes them both useful and problematic to the environment. More specifically, their durability lends to their persistence in the environment and their low density enables them to float and be dispersed great distances by wind and water.

Early environmental studies of marine litter, starting about 50 years ago, linked this form of pollution to the societal use of plastics (Ryan, 2015). In a chronology of plastics in the environment by Ryan (2015), the earlier decades consisted of marine studies that focused on distribution, abundance, and ingestion by marine life and their entanglement, and policies were developed for environmental protection.

In the more recent decades, there were startling reports of mid-ocean ‘garbage patches’ starting with the Great Pacific Garbage Patch in the mid-1990s (Moore et al., 2001), and the increasing awareness of microplastics in the world’s oceans.

Only in the last few years has there been an emergence of studies on microplastics in freshwater and terrestrial environments, rather than a sole focus on marine systems (Lambert and Wagner, 2018). Microplastics are considered to be ubiquitous in both marine and freshwater environments.

Microplastics can enter the aquatic environment through several pathways, such as through effluent from water pollution control plants (WPCPs; Mason et al., 2016), through combined sewage overflow events, incidental release from the use of plastic products (e.g. the wearing of tires), from industrial processes, by atmospheric deposition (Lambert and Wagner, 2018) and through the degradation of larger plastic debris in terrestrial or aquatic systems. The densities of urban populations and plastics industries can affect the abundance and type of microplastics in a nearby water body (Ballent et al., 2016).

Substantial amounts of microplastics may settle-out or float during primary or secondary treatment of wastewater. Instead of being released to waterways with effluent, these separated microplastics may be applied as biosolids (reclaimed sewage sludge) to agricultural lands in the terrestrial environment (Nizzetto et al., 2016).

Once released into the environment, microplastics do not remain stationary but instead move between terrestrial, freshwater and marine systems at varying rates. Within a riverine system, hydrology (including flow conditions) and stream morphology affect the movement of microplastics because they can cause obstructions and other “stranding” scenarios.

Degradation by various processes, or by certain processes in combination, can affect the fate of microplastics. Degradation by ultraviolet (UV) radiation can vary by site-specific conditions and processes that affect sunlight exposure, such as the burial of plastics into sediment that blocks sunlight (Lambert and Wagner, 2018). Fragmentation of plastics into smaller and smaller pieces also affects their persistence and mobility.

In marine environments, persistent organic pollutants (POPs; e.g., DDT and PCBs) are known to sorb to microplastics, affecting the mobility and bioavailability of these contaminants. Very little is known about the association of contaminants with microplastics in freshwaters, but other emerging contaminants such as pharmaceuticals, personal care products and flame retardants may occur with them (Lambert and Wagner, 2018).

Environmental impacts

Within marine food webs, microplastics have been detected in the digestive tracts of organisms at nearly every trophic level, and recent studies in freshwater systems are in agreement with these reports (Cole et al., 2013; Eerkes-Medrano et al., 2015). Microplastics may affect the physiological functioning of animals, either through the leaching of accumulated organic pollutants into the stomach lining of fishes that consume them, physical blockage of the digestive system, or simply by taking up space that could otherwise be occupied by nutritional food sources (Bakir et al., 2014; Wright et al., 2013).

Avio et al. (2015b) presented the first evidence of microplastics in hepatic tissue (the liver) of fish, suggesting transport out of the digestive system and into other tissues. A similar occurrence was observed in marine mussels, validating the potential risk of accumulation and trophic transfer of microplastics from prey to predator (e.g., from fish to seabirds) in marine food webs (Von Moos et al., 2012; Avio et al., 2015a; Lambert and Wagner, 2018) and likely freshwater food webs as well.

Microplastics may be capable of facilitating bioavailability of harmful contaminants (Koelmans et al., 2013) and pathogens, and researchers need to understand the adverse effects that could occur to populations from these types of contamination (Helm, 2018).

Microplastics in the Lake Simcoe watershed

Considering the extent of microplastic pollution in larger systems such as the Great Lakes (see section, Additional Ontario studies and resources), it is important to understand the extent of this pollution in other inland lakes of similar size (Wagner et al., 2014; Anderson et al., 2017), especially with significant urban areas such as Lake Simcoe. Plans are underway by the Ministry of Environment, Conservation and Parks (MECP) and academic partners for research and sampling of microplastics in Lake Simcoe, including studies of water, sediment and fish.

>In 2018, a joint project with the University of Toronto and MECP assessed the quantity and types of microplastics in sport fish species of Lake Simcoe (pike, trout, whitefish, perch, bass and walleye). The research also examined if plastic particles are able to enter edible tissues from the stomachs of fish, and whether any chemical contaminants associated with the microplastics (such as plasticizer additives used in some plastics) are present in the fillets of the fish. Studies of this nature were also carried-out in Lake Ontario.

In an effort to understand the distribution and composition of microplastic pollution in Lake Simcoe, the MECP collected water and sediment samples from the lake in the vicinity of urban areas, including from Kempenfelt and Cook’s bays, near Orillia and Georgina Island and in the Main Basin.

Researchers at the University of Windsor and Trent University are working to calculate loads of microplastics applied to agricultural soils through biosolids in Lake Simcoe catchments, and quantify rates and processes involved in transportation of microplastics from soils to the freshwater environment. These studies form part of a larger multi-national program under the WaterWorks Joint Projects Initiative (JPI), which seeks to determine the impacts of microplastics in agrosystems and stream environments.

The program consists of five interconnected work packages that look at exposure to microplastics (monitoring), impacts (laboratory experiments), decision support tools (modeling), stakeholder engagement, and scenario assessment. The project recognises the importance of developing shared management solutions, and ultimately aims to identify resolutions to issues of microplastic applications which will safeguard agricultural sustainability, economic goals, and human and agricultural health.

Additional Ontario and Great Lakes studies & resources

Research has occurred or is underway to gain a better understanding of microplastics in the Great Lakes. Goals of these studies include understanding the sources of microplastics to the Great Lakes, their composition and their distribution, abundance and fate once they enter these water bodies.

Zbyszewski and Corcoran (2011) published a Great Lakes microplastics study where plastic pellets (now termed microplastics) made up the majority of plastics collected along an industrial sector of the Lake Huron shoreline.
Zbyszewski et al. (2014) studied plastic debris in the shorelines of Lake Erie and Lake St. Clair.
Eriksen et al. (2013) published a study of microplastics in the Great Lakes where manta trawl nets were used to sample the surface waters of lakes Superior, Huron and Erie. Microplastics were found at almost all of the 21 sites, with Lake Erie typically having the highest abundances. The authors note that there were significant amounts of coal ash and coal fly ash (from coal burning power plants in the area) that could have been mistaken as microplastics if additional elemental and chemical analysis had not been performed.
Surface water samples were collected in 2014 from nearshore sites in Lake Erie and Lake Ontario and examined for microplastics (MOECC, 2016). Elevated quantities of microplastics were observed after rainstorms, meaning that movement of debris through stormwater runoff is a significant source to lakes. To investigate urban sources further, urban streams in the Toronto area and effluent from a WPCP were also sampled. These contained microplastics with a larger proportion of microbeads in wastewater effluent than streams.
Castaneda et al. (2014) studied microplastics in sediments of the St. Lawrence River.
Microplastic particles were observed in sediment cores collected from the centre of Lake Ontario and from near the outlet of the Niagara River in Lake Ontario (Corcoran et al., 2015).
In a study of nearshore sediments, greater abundances of microplastics were found in the vicinity of urban and industrial regions including Humber Bay and Toronto Harbour in Lake Ontario (Ballent et al., 2016).
Driedger et al. (2015) presented a review paper of plastic debris in the Great Lakes.
Studies led by the MECP are scheduled to continue until 2019 and effects from the phasing-out and prohibition of sales of microbeads (see section Action to reduce microplastics in the environment) will be considered (Helm, 2018).

Actions to reduce microplastics in the environment

Recent concern around the potential ecological impacts of microplastics has led to proposed legislation to eliminate their use in personal care products. In June of 2016, microbeads were listed as a toxic substance under Schedule 1 of the Canadian Environmental Protection Act, 1999 [Environment and Climate Change Canada (ECCC), 2018], enabling the Canadian government to regulate and manage risks to the environment.

As outlined in the Microbeads in Toiletries Regulations, the manufacture, import and sale of toiletries containing microbeads will all be prohibited by July 1st, 2019 (ECCC, 2017). Many corporations in Ontario have already stopped dealing with products that contained microbeads ahead of these bans, and the MECP continues to work with stakeholders to phase-out the use of microbeads in all personal care products sold in Ontario.

Globally, researchers are working not only to study and understand microplastic pollution, but also to invoke positive change through catalyzing policy. For example, Rochman and Browne (2013) advocated that the most harmful types of plastic (including those that cannot be recycled or reused) be listed as hazardous substances, especially in the biggest plastic waste-producing countries.

Though there are naturally gaps in our understanding of microplastic pollution (as in all sciences), there is enough evidence of deleterious effects (including widespread and irreversible harm) that policy makers should take action immediately to mitigate the problem (Eriksen et al., 2018, Rochman et al., 2016). Indeed many governmental agencies have started programs that focus on plastic pollution, such as within the United Nations Environment Programme (UNEP, 2018), and there are campaigns such as Operation Clean Sweep that rally engagement and support from plastics industries to protect the environment (American Chemistry Council, 2018).>

Eriksen et al. (2018) outlined the following solutions to plastic pollution:

identification and quantification of upstream microplastic sources through research,
zero waste strategies (by using reusable containers, for example),
policies that uphold extended producer responsibility (consider environmental impacts through product design), and,
the development of business solutions.

Eriksen et al. also promoted upstream intervention and reduction of plastic pollution in order to prevent the formation of secondary microplastics in terrestrial and freshwater environments (some of these eventually making their way to marine systems). Clean-up of microplastics once they are in natural water bodies is not currently possible. Furthermore, by working upstream there is a better chance to use plastics as fingerprints connecting to the sources, rather than working downstream where the plastic fragments have degraded too much to link to the original product, and polluter.

The MECP is acting on waste problems through new legislation, the Waste Free Ontario Act (2016), in which problems of waste generation are being tackled by aiming for more resource recovery, a circular economy and eventually a zero-waste Ontario (MOECC, 2018). In a circular economy, products are reused, recycled or incorporated into new products, rather than being discarded.

Everyone needs to be part of the solutions to waste in Ontario, reduce your use of plastic whenever possible!

References

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Anderson JC, Park BJ and Palace VP. 2016. Microplastics in aquatic environments: implications for Canadian ecosystems. Environ. Pollut. 218: 269-280.

Anderson PJ, Warrack S, Langen V, Challis JK, Hanson ML and Rennie MD. 2017. Microplastic contamination in Lake Winnipeg, Canada. Environ. Pollut. 225: 223-231.

Bakir A, Rowland SJ and Thompson RC. 2014. Enhanced desorption of persistent organic pollutants from microplastics under simulated physiological conditions. Environ. Pollut. 185: 16-23.

Ballent A, Corcoran PL, Madden O, Helm PA and Longstaffe FJ. 2016. Sources and sinks of microplastics in Canadian Lake Ontario nearshore, tributary and beach sediments. Mar. Pollut. Bull. 110: 383-395.

Castañeda RA, Avlijas S, Simard MA and Ricciardi A. 2014. Microplastic pollution in St. Lawrence River sediments. Can. J. Fish. Aquat. Sci. 71: 1767-1771.

Cole M, Lindeque P, Fileman E, Halsband C, Goodhead R, Moger J and Galloway TS. 2013. Microplastic ingestion by zooplankton. Environ. Sci. Technol. 47: 6646-6655.

Corcoran PL, Norris T, Ceccanese T, Walzak MJ, Helm PA and Marvin CH. 2015. Hidden plastics of Lake Ontario, Canada and their potential preservation in the sediment record. Environ. Pollut. 204: 17-25.

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Eerkes-Medrano D, Thompson RC and Aldridge DC. 2015. Microplastics in freshwater systems: A review of the emerging threats, identification of knowledge gaps and prioritisation of research needs. Water Res. 75: 63-82.

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New Report

Chemical Contaminants in Lake Simcoe and its Tributaries

in 2015, a study was undertaken to investigate levels of chemical contaminants in the surface water and sediments of Lake Simcoe and its tributaries. The contaminants included in this study were chosen based on historical use within the watershed, previous research undertaken (such as the LSRCA 2004 study), and literature from similar areas in the Great Lakes Region.

Read Chemical Contaminants in Lake Simcoe and its Tributaries

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