Sampling site and pellet characteristics. A) Sampling pellets from a 1 × 10 m quadrat along the strandline of a Lake Superior beach. B) Examples of three distinct types of pellets. Clockwise from top left: black, oblate; black, cylindrical; black, oblate, rimmed. Note that the three types are of different sizes. C) Examples of the three most common shapes, clockwise from upper left: two circular pellets (rifle beads), two oblate, and three cylindrical. D) and E) Distinguishing traits of pellets sampled. Clockwise from top left in D: rimmed and nodule; dimple and dirty; rough and broken; rimmed and hole; rimmed. Clockwise from top left in E: groove; dimple and nodule; lines and dirty; lines and dirty. F) Weathered pellets with distinguishing traits such as dirty, rough and broken. The two lower left pellets are coalesced (joined together).

Sampling site and pellet characteristics. A) Sampling pellets from a 1 × 10 m quadrat along the strandline of a Lake Superior beach. B) Examples of three distinct types of pellets. Clockwise from top left: black, oblate; black, cylindrical; black, oblate, rimmed. Note that the three types are of different sizes. C) Examples of the three most common shapes, clockwise from upper left: two circular pellets (rifle beads), two oblate, and three cylindrical. D) and E) Distinguishing traits of pellets sampled. Clockwise from top left in D: rimmed and nodule; dimple and dirty; rough and broken; rimmed and hole; rimmed. Clockwise from top left in E: groove; dimple and nodule; lines and dirty; lines and dirty. F) Weathered pellets with distinguishing traits such as dirty, rough and broken. The two lower left pellets are coalesced (joined together).

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Industrial, pre-consumer pellets are a major type of plastics pollution found on shorelines worldwide. This study investigates the distribution and characteristics of plastic pellets accumulated on beaches of the Laurentian Great Lakes of North America and provides a “snapshot” of pellet distribution in a lake system that accounts for 21% of the wo...

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... sediment on the beach; if this proved difficult, samplers collected sediment and brought it back to the lab for measurement, iii) collect all plastic debris along the strandline. The latter step was conducted by stretching a 10 m measuring tape perpendicular to the strandline and collecting pellets and other plastic debris within 1 m of the tape (Fig. 2a). Plastics from only the top 5 cm of the beach surface were collected using bare hands if the sediment was wet. Metal sieves were used if the sediment was dry and fine enough to pass through the sieve openings, thereby leaving pellets and plastic debris >2.5 × 3 mm remaining in the sieve. Pellets and other plastic debris were stored in ...
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... the course of six months, the pellets were separated from other plastic items and each pellet was characterized according to size, shape, diagnostic trait, visible weathering, and color ( Fig. 2b-f). Information concerning each pellet was entered into a database for statistical analysis. The size of each pellet was measured with a ruler by finding the plane of maximum projection, then measuring the long (l) and intermediate (i) axes and multiplying them together. The short axis (thickness) of each pellet was not measured due to ...
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... types on each beach were assigned to pellets of the same size, and with the same color, shape, diagnostic feature, and visible surface weathering (Table S2; Fig. 2b). Pellet types on different beaches within the same lake were compared only for Lake Superior. The sheer volume of different pellets on beaches of the other four lakes prohibited type comparisons for this part of the study. Pellet sizes varied between 2 and 42 mm 2 , with a median of 12 mm 2 and a mean of 13.7 mm 2 overall. Mean sizes ...
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... pellet size, that is, to test that there is a significant difference in mean pellet size between lakes. This was significant at the p < 0.01 level. The predominant pellet shape overall was oblate (Fig. 4a). Cylindrical, oblate, and circular pellets were the most common shapes and were identified in samples from beaches on all five Great Lakes (Fig. 2c). A total of 9329 pellets had no diagnostic traits. Of the other 3266 pellets, dimples were by far the most common (Lakes Ontario, Huron, Michigan and Superior), followed by lines (Lakes Ontario and Huron) and nodules (Lake Ontario) (Figs. 2d, e, 4b). The sampled quadrats on the three beaches with the greatest number of pellets show ...
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... pellets were the most common shapes and were identified in samples from beaches on all five Great Lakes (Fig. 2c). A total of 9329 pellets had no diagnostic traits. Of the other 3266 pellets, dimples were by far the most common (Lakes Ontario, Huron, Michigan and Superior), followed by lines (Lakes Ontario and Huron) and nodules (Lake Ontario) (Figs. 2d, e, 4b). The sampled quadrats on the three beaches with the greatest number of pellets show that Baxter Beach (Huron) and Bronte Beach (Ontario) contained the largest variety of pellets with respect to distinguishing traits, whereas Rossport beach (Superior) mainly contained pellets with no distinguishing ...
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... of each of 436 PE pellets analyzed by FTIR. Peaks in the spectra between 1710 and 1775 cm −1 are increased absorption peaks, which are indicative of oxidized material. Oxidation was classified as low if there was little to no evidence of absorption peaks at about 1715 cm −1 relative to the characteristic PE peak height at around 1471 cm −1 (Fig. S2). The results in Table S1 indicate that 13.7% of the pellets analyzed were weathered, with the greatest percentage of weathered pellets in Lakes Ontario, Michigan and Erie. We also attempted to visually note the number of pellets that appeared extensively weathered, as determined through color change (fading or yellowing), increase in ...
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... to visually note the number of pellets that appeared extensively weathered, as determined through color change (fading or yellowing), increase in surface roughness (e.g. pits and microfractures), embrittlement, and abundance of external particles adhered to surfaces (e.g. Zbyszewski and Corcoran, 2011;Brandon et al., 2016;Cai et al., 2018) (Fig. 2f). Of the 15,595 pellets examined, 2.4% showed extensive evidence of weathering (Table S3). By individual lake, the percentages of pellets that were visually identified as weathered were <0.01% (Superior), <0.01% (Michigan), 2% (Huron), 10.6% (Erie), and 0.04% (Ontario). A comparison of the results indicates that visual characterization ...

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... Nevertheless, estuaries are known sinks for many environmental pollutants, and are subject to inputs of plastics from terrestrial, marine and freshwater environments (Vermeiren et al., 2016). Additionally, estuaries are often locations where urban centres develop, and human population densities have consistently been associated with plastic pollution (Browne et al., 2011;Nakao et al., 2020;Corcoran et al., 2020;Vetrimurugan et al., 2020). Of particular ecotoxicological importance is pollution by microplastics (plastics ≤5 mm, Arthur et al., 2009, Hidalgo-Ruz et al., 2012, because their small size allows for their uptake by a range of organisms throughout the food web (Au et al., 2017). ...
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