GBF Report - Polystyrene Foam

13 The physical properties of plastic have important consequences for the pattern and distribution of plastic pollution in the environment. Since exposed PS foam can easily be chewed by animals, the material breakup is common. Muskrats are an example, as noted by the Washington Department of Fish andWildlife: “Muskrats will burrow into floating docks, generally those floating on Styrofoam, scattering the broken white foam along the shoreline. This becomes an environmental danger, due to birds and other small animal eating this foam” (Washington Department of Fish &Wildlife, 2020). As a result of the widespread use of PS foam and its mismanagement, PS foam has become widespread in habitats around the world (Hinojosa and Thiel, 2009; Moore et al., 2001). PS fragments are found on shorelines (Garrity and Levings, 1993), the open ocean (Morét-Ferguson et al., 2010), and the sea floor (Keller et al., 2010). However, often the sources of the debris are often unknown. While some studies identify macro debris as cups and plates, fast food containers, floral Styrofoam, grocery packaging, beverage container, packing foam, buoys, and floats, often the majority of PS foam pieces are small fragments with unknown origins (Garrity and Levings, 1993; Heo et al., 2013; J. Lee et al., 2013; Morét-Ferguson et al., 2010). 3.2 Navigation and aesthetics Dangers to navigation and aesthetic issues related to floating PS debris are also of concern. In sufficient size or quantity, PS foam debris poses a hazard to boat traffic. Navigation hazards have even prompted local PS dock floats bans (Missouri Department of Natural Resources, 2006). Often EPS litter on lakes is so common they are colloquially referred to as “icebergs” (ERDC, 2009). In addition to being a hazard, PS debris is reported to litter shorelines and impacts the aesthetics of beaches around the world (Gregory, 2009; ReVelle and ReVelle, 1992). A study in Illinois found that that the absence of litter and floating debris were ranked of high concern by lake managers and recreators (Mullens and Lant, 1991). The economic impact of plastic debris can be considerable, especially for municipalities that regularly need to remove beach litter to maintain tourist revenue (Gregory, 2009). 3.3 PS foam low recycling rates While there are some efforts to recycle used PS foam floats, these materials have a low recycling rate. Recycling of EPS and XPS is possible, although due to high costs of transport and its low value, PS foam is often not recycled (Ragan, 2007). Dock foam can be especially expensive to transport and dispose of since used dock foam is often waterlogged (Missouri Department of Natural Resources, 2006). In some areas, recycling programs have been developed as an effort to recover the material where dock foam has been banned (Missouri Department of Natural Resources, 2006). However, these programs have seen limited success due to costly landfill tipping fees for waterlogged foam and no commercial market for PS dock foam (Missouri Department of Natural Resources, 2006; “Sheltered workshop recycling dock foam,” 2016). 3.4 Distribution of PS foam litter in the Great Lakes and St. Lawrence River The Great Lakes St. Lawrence River Basin is the largest surface freshwater resource on Earth, accounting for a full one-fifth of the world’s freshwater supply and supplying essential drinking water to 40 million people. The Great Lakes are home to some of the world’s most unique ecosystems; they provide continentally significant habitat for large numbers and diverse species of North America’s fish, migratory birds, waterfowl, amphibians, reptiles and invertebrates, as well as many different underwater and coastal plant species. PS foam is present throughout the Great Lakes in sediment, surface water, and wildlife, littering a critical freshwater resource for people and wildlife. 3.4.1 Transport Research shows that plastic pollution often follows the same hydrological pathways as water (Windsor et al., 2019). In the Laurentian Great Lakes, transport models show that plastic follows patterns driven by water movement and wind (Hoffman and Hittinger, 2017). Hoffman and Hittinger (2017) recognized good correlations between plastic abundances in beach surveys (Zbyszewski et al., 2014) and modeled accumulation for Lake Huron. Particle movement can depend on many factors, such as shape, size and density, all which can change