Microplastic pollution on Cape Cod beaches 1

Plastic Beach (The Arrival) Spatial heterogeneity of microplastic pollution on Cape Cod beaches and the impacts of different hydrographic sources

Hector Ricardo Salazar Connecticut College

Project Mentors: Rut Pedrosa Pamies*, JC Weber, Maureen Conte Ecosystems Center Marine Biological Laboratory

Semester in Environmental Science Class of 2018

*Corresponding author: Rut Pedrosa Pamies [email protected]

Microplastic pollution on Cape Cod beaches 2

ABSTRACT

Plastic has become a large source of global pollution; it has entered our marine ecosystems and we are only beginning to see the effects on ecosystem health, animals, and humans. Plastic is a great threat to the environment due to its non-biodegradable properties and long resonance time once in the environment. Plastic debris now contaminate sandy, estuarine, and subtidal habitats in the Europe, Asia, and the Americas, with the global extent of microplastic contamination remaining unknown. This study aimed to assess the distribution of microplastics on Cape Cod beaches, and understand how microplastic contamination is influenced by various hydrodynamic sources as well as local and regional contamination sources. Microplastics are the result of these degraded discarded plastics that become ubiquitous in the marine environment; they are defined as plastic particles less than 5 mm in size. The results of this study suggest that microplastics are ubiquitous in coastal systems of Cape Cod, with a highly variable distribution. Total abundance was about an order of magnitude higher in Nantucket Sound (60g/m3) and Buzzards Bay (120g/m3) than Cape Cod Bay and Atlantic Ocean beaches (~15g/m3), possibly reflecting seasonal and year-round population trends. The most abundant microplastics found on Cape Cod beaches in this study were between 63-500 μm, suggesting the greatest contamination is a result of regional pollution sources. The smallest size fraction of plastics had the highest abundance on Buzzards Bay beaches (80g/m3) compared to all other beaches on Cape Cod (~10-20g/m3), suggesting sourcing from increased runoff from populated watersheds and the tidal characteristics of the Buzzards Bay basin. Furthermore, the variability of microplastics in this study is consistent with variability in microplastic abundance in the northeast Atlantic Ocean. The implications of microplastic contamination is one of global concern; microplastics are an increasing threat to marine and coastal environments. Plastic contamination is a result of anthropogenic consumerism and waste discard, there is nothing else in the environment that resembles this synthetic parasite.

Key words: microplastics, plastic, pollution, coastal ecology, marine ecology, anthropogenic contamination, Cape Cod, New England, plastic distribution, environmental contamination, debris

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INTRODUCTION

“There are, in short, a multitude of ways for trash to escape and plastic to go missing. But there is only one ultimate end point for this wild trash: the greatest future, the biggest surface, the deepest chasm, the broadest desert and the largest burial ground on the planet. It's the ocean...No matter where you are, there’s no getting over it, no getting away from it,”... “It’s a plastic ocean now … We’re putting everything in the ocean on a plastic diet.”

― Edward Humes, Garbology: Our Dirty Love Affair with Trash

The implications of microplastic contamination is one of global concern. Contamination of the marine environment is an increasing problem, threatening the health of marine and coastal ecosystems, organismal health, as well as human health (Law et al., 2010; Andrady 2011). The first reports of plastic litter in the world’s oceans were as early as the 1970s. Understanding the sources (both local and regional) as well as the current magnitude of microplastic contamination is extremely critical in the first steps to mitigating this chronic, global environmental issue.

Plastic has become a large source of global pollution. It has entered our marine ecosystems and we are only beginning to see the effects on the ecosystem health, animals, and humans. In 2016, global plastic production totaled 336 million metric tons. Plastics are used in a wide variety of products used every day, displacing other materials previously used such as wood, metal and glass (Statista 2018). We live in a high consumption society that thrives on a capitalist market; based upon use and discard principles of consumption. Therefore, the average person in the United States will have produced 102 tons of trash in their lifetime (Humes 2013). The average person does not consider the impacts of waste disposal, or specifically, where their discarded waste will end up. Current estimates show that at least 8 million pieces of plastic are entering the world’s oceans daily, and there is an estimated 5.25 trillion plastic particles floating in the ocean; plastics currently account for 60-80% of marine litter (Xanthos et al 2017). Much of these discarded single use plastics have settled into coastal marine habitats, as a result of ocean current redistribution.

In order to understand the impacts of microplastic pollution, how much is concentrated in certain areas, what its possible sources are, and how it is distributed are critical pieces of information. Plastic debris now contaminates sandy, estuarine, and subtidal habitats in the United Kingdom, Singapore and India, with the global extent of microplastic contamination remaining unknown. However, anyone who has visited a beach in recent years has definitely encountered discarded cigarette butts, broken beach toys left behind, or pieces of fishing gear or buoys that have washed ashore (Law 2017). Microplastics are the result of these degraded discarded plastics that become ubiquitous in the marine environment; they are defined as plastic particles less than 5 mm in size (Coppock et. Al 2017). Microplastic contamination can span from coastlines to the Microplastic pollution on Cape Cod beaches 4 deep-sea and is accumulating within these habitats, outnumbering larger debris (Browne et. al 2006). In the last 50 years, there has been an increase in plastic particles in surface waters of the northeast Atlantic Ocean. Major pathways for microplastics to enter the environment include: sewage waste and wastewater systems, fragmentation of larger plastics, small particles used as abrasives in cleaning products, and spillage of plastic powders and pellets; another major source is direct contamination of habitats through human refuse and litter. Spatial patterns may influence sources of microplastics, with more material along shorelines adjacent to densely populated areas, which generate a greater abundance of large debris and produce millions of tons of sewage every year.

Few studies have addressed plastic pollution in New England coastal systems, even though there have been studies confirming the presence of plastics on the outer coast of Cape Cod, Massachusetts (Schneiderman 2016). To assess the impact of microplastics on coastal ecosystems, it is critical to understand how much plastic is present and whether it is concentrated in certain areas. This research project assessed the abundance and distribution of microplastic pollution on Cape Cod Beaches. For the purpose of this study, Cape Cod was divided into four “zones” referring to the coastal systems along the four sides of the cape; to the north is Cape Cod Bay, the Atlantic Ocean to the east, Nantucket Sound in the south, and Buzzards Bay to the west. These four bodies of water have their own unique hydrodynamic sources and circulation patterns (see background section). Circulation patterns can control the transport and deposition of pollutants throughout coastal ecosystems. Factors that influence the direction of currents include water temperature, weather/ storm activity, and wind patterns. Understanding the movement of ocean water, specifically near coastal systems, can provide critical information in understanding deposition of oceanic debris and pollutants. Additionally, understanding land uses can also provide insight into pollution sources in coastal ecosystems. Land use information can provide possible local sources of plastic pollution that directly enter coastal systems.

I hypothesized that microplastics would be ubiquitous on Cape Cod beaches, as a result of local plastic pollution as well as regionally sourced and carried by the ocean currents surrounding the cape. In order to quantify the abundance and distribution of microplastics on Cape Cod beaches, sediment samples were collected from twelve beaches all around Cape Cod. In the laboratory, microplastics were separated from sediment via microplastic flotation. I found that the smallest microplastic size fraction (63 -500 μm) was the most abundant on Cape Cod beaches. Additionally, beach characteristics as well as land usage in coastal regions is correlated with the abundance of plastic on beaches, which has implications for microplastics resonance time on coastal systems as well as local and regional sources for plastic pollution. Overall there was high variability and no consistent difference in the abundance of microplastics across the four zone regions.

Microplastic pollution on Cape Cod beaches 5

BACKGROUND

Cape Cod is located at the juncture of two major ocean biogeographic regions; waters north of Cape Cod are influenced by Gulf of Maine and Labrador currents, while the waters south and east of Cape Cod are influenced by the New England Shelf and occasionally warm core rings spun off the Gulf Stream (Cape Cod Ocean Management Plan 2011). In Cape Cod Bay, the winds strongly influence the direction of circulation and the connectivity between the Gulf of Maine and the Bay (Leo et. al). Past studies (Geyer et. al 1992) have confirmed that surface water circulation in Massachusetts Bays (connected to Cape Cod Bay) generally flows counterclockwise (see figure 1) entering from the Gulf of Maine. Buzzards Bay is a relatively shallow estuary system with circulation patterns influenced primarily by tidal and wind-driven water flow. Its location and semi-closed nature result in tidal patterns different from the nearby waters of Vineyard Sound and Cape Cod Bay (Ecology of Buzzards Bay). Nantucket Sound is shallow with openings to the Vineyard Sound, inner New England shelf, and the western Gulf Stream, with overall strong and variable tidal currents; additionally, Nantucket Sound is a partial “flow-through” system, with two-way exchange of water through its three openings (Nantucket Sound Circulation).

METHODS

Sample Collection

Beach Selection: In order to quantify the abundance and distribution of microplastics on Cape Cod beaches, sediment samples were collected from twelve beaches all around Cape Cod (3 beaches in each of the 4 zones (Table 1 and Figure 2). The beaches were selected based on their locations on the coast of each of the four Cape Cod zones. The beaches were all well spread out along the coasts in order to get the best representation of Cape Cod beaches in terms of beach characteristics, proximity to potential pollutant sources (homes, commercial space, etc.), and beach maintenance practices (i.e. beaches that were not known to be regularly cleaned). The beaches selected are listed in Table 1 and mapped in Figure 2. At each beach, the high tide line was sampled at a minimally disturbed location. The collection period was following high tide or near the lowest tide (and high tide line was determined using sediment clues). Prior to beginning sediment collection, temperature, weather, barometric pressure, wind, and any potential beach conditions of significant importance were noted (using a templated data collection sheet). Pictures of the sampling location were taken using prior archaeological surveying techniques. A white board was incorporated into each photo with the beach name, date, time, weather conditions, and wind speed. Additionally, a cell phone Microplastic pollution on Cape Cod beaches 6

GPS app aided in providing specific coordinates of sample location which was used in GIS for further land use analysis.

Sediment Collection: A 50 meter transect was laid along the high tide line (figure 7). Within that transect three replicate plots (50 X 50cm) were placed and their position along the transect was documented. Surveying included noting temperature, weather, barometric pressure, wind, and any potential beach conditions of significant importance. For each replicate, sediment was collected down to a measured depth of 2 centimeters, using rulers and leveled line to get as accurate of a depth as possible. The sediment from each replicate was placed into a bucket, and the depth inside the bucket was determined and recorded for volume calculations. Once finished at a site, the sediments were packed into a labeled bag (Name, Date, Location, Replicate #), and stored securely for transportation. As many samples were collected in a day from the twelve Cape Cod beaches based on tidal activity and weather (optimal collection period was following high tide or at lowest tide of given day).

Analytical Methods

Preparation of Calcium chloride solution: For laboratory analysis, a solution of 1.2 kg/L CaCl2 was used. To prepare the Calcium chloride, it was determined that 660 grams of calcium chloride (in the form of ice melt flake product (Qik Joe Calcium Chloride Ice Melt 20 lb. Pellet Item no.7003411) was needed for every liter of distilled water to achieve desired density of 1.2 kg/L. Calcium chloride solution was prepared and stored in 20 L carboys.

Microplastics Flotation: Plastics were isolated from the beach sediment using a density separation method. Collected sediment was placed into large tubs (1 bag at a time in each tub) obtained at hardware store (Ace Utility Tub Item no.1522929/ST3608ACE) and 35-40 liters of CaCl2 solution was added to the tub (1 bag = 1 replicate) The contents in the tub were stirred using a wooden stirring rod for approximately 30 seconds and then allowed to sit for ten minutes. Following the 10 minutes, the plastics that floated to the surface were aspirated from the surface into a vacuum flask. This process was repeated three times for each sample. After the three rounds of floatation, the aspirated contents were poured through a sieve and rinsed with fresh tap water. The contents in each sieve (sizes A - 5.6 mm, B - 1 mm, C - 500 µm, D - 63 µm) were then carefully rinsed into pre-labeled tins and dried. Before drying, the plastics were sorted out from the organic matter through visual inspection under a lighted magnifier for the three largest fractions. For the smallest 63-500 µm fraction, organics were removed using 69% HNO3 (nitric acid). The plastics in each in each size fraction were all weighed once dried overnight at 60C.

Grain Size Distribution: Grain size distribution was assessed in order to quantify the sediment characteristics of each beach that was sampled. A 250mL subsample was taken from Microplastic pollution on Cape Cod beaches 7 each beach, dried, initially weighed for total weight, and then sieved through the same size sieves used for microplastic size fractionation (5.6 mm, 1 mm, 500 μm, and 63 μm). Sediment in each size fraction were placed in pre-weighed tins and the mass of each size fraction tin was obtained. An additional size fraction was added for grain size to account for silt and clay particles [<63 μm] (this was accomplished by subtracting the total mass of the size fractions from the original dry weight.

Nitric Acid Oxidation: There was a substantial number of organic particles that could not be separated from the microplastics following the flotation methods and sieving. To eliminate organics built up into the extracted microplastics samples, a select number of samples were subjected to oxidation by nitric acid. Samples that underwent this additional step included samples with high amounts of organics that could not be removed by hand. The smallest size fraction (63 -300 μm) were all subjected to this procedure, as it was not possible to separate organics from microplastics at this small size. Any other size fraction samples with large quantity of organic matters were subjected to this procedure at our discretion. A 69% nitric acid (HNO3) solution was used. The samples were transferred to 50mL falcon tubes using distilled water to help transfer samples. All tubes were dried before adding HNO3. The samples were allowed to sit overnight in a water bath at 40°C to allow for maximum oxidation of organic material. To remove the HNO3, the HNO3 was diluted with water and carefully poured through a funnel lined with Nitex mesh (either 333µm or 63µm) so that our smallest size fraction would be retained. The material on the mesh was rinsed back into the falcon tube and the tubes were then filled with CaCl2 solution for re-flotation of microplastics to separate from any remaining organic debris or settled lithogenic material previous floating due to being aggregated in buoyant organic matter. The contents on the surface were transfer pipetted into a 53 μm sieve, rinsed with distilled water, and transferred to pre-weighed tins, and dried overnight at 60°C for determination of dry weight.

RESULTS

Grain size distribution: Grain size was used to assess the distribution of sediment on Cape Cod beaches and quantify these beach characteristics. On the Buzzards Bay coast, New Silver Beach and Chapoquoit Beach shared similar beach characteristics, composed mostly of medium sand [92% New Silver, 88% Chapoquoit] (Figure 9A); Megansett Beach varied from New Silver and Chapoquoit, composed of 47% medium sand and 39% fine sand (Figure 8A); the percentages of medium sand ranged from 46.67% - 91.02%, with a mean of 87.37%; fine sand ranged from 2.51%-38.68%, with a mean of 3.65% (Figure 9A). On the Nantucket Sound coast, the grain size distribution varied across the three beaches. Mashpee Town Beach was composed mostly of coarse sand [57%] and medium sand [40%]; Seagull beach was composed mostly of coarse sand [34%] and medium sand [51%]; Ridgevale Beach was majority medium sand [77%] (Figure 8B); the percentages of coarse sand ranged from 11.3% - 183.1%, with a mean of 33.91% and medium sand ranged from 39.22% - 80.67%, with a mean of 50.50% (Figure 9B). On the coast of the Atlantic Ocean, the sediment composition was majority medium sand. Lighthouse Beach was 91% medium sand; Longnook Beach was 38% coarse sand and 55% medium sand; Race Point Beach was 74% medium sand (Figure 8C); the percentages of coarse Microplastic pollution on Cape Cod beaches 8 sand ranged from 5.70% - 35.44%, with a mean of 23.24%; fine sand ranged from 50.90% - 91.20%, with a mean of 73.95% (Figure 9C). Along the Cape Cod Bay coast, the grain sizes were greatly varied. Scusset Beach consisted mostly of gravel [26%], coarse sand [42%] and medium sand [53%]; Sandy Neck Beach consisted mostly of gravel [52%] and medium sand [30%]; Corn Hill Beach consisted mostly of coarse sand [34%] and medium sand [62%] (Figure 8D); gravel ranged from 1.24% - 52.14%, with a mean of 20.55%; coarse sand ranged from 4.08% - 33.68%, with a mean of 32.98%; medium sand ranged from 29.70% - 61.70%, with a mean of 41.86% (Figure 9D). Grain size distribution varied overall across Cape Cod beaches; however, overall the medium sand predominated most beaches.

Microplastics Abundance: Taking into account only the size fractions smaller than 5 mm, Buzzards Bay had the largest overall microplastics abundance out of the four zones on Cape Cod, with a total of 77. 46 푔/푚3; Nantucket Sound had the second largest abundance of microplastics with 21.64 푔/푚3; the Atlantic Ocean beaches had 19.64 푔/푚3; and Cape Cod Bay had the lowest microplastics abundance value of 9.34 푔/푚3(Figure 14).

On Buzzard Bay beaches, the smallest size fraction (63-500 μm) dominated. Megansett Beach had the most plastics [38%] at the C [500 μm -1 mm:6606.66푚푔/푚3] and [59%] at the D [63-500 μm:10200푚푔/푚3] size fractions; New Silver Beach was dominated by size fraction [91%] D (63-500 μm) with 3800푚푔/푚3; Chapoquoit Beach was more variable in microplastics abundance, with 22% of microplastics in the B [1-5 mm: 4640푚푔/푚3] size fraction, 13% in the C [500 μm -1 mm: 2740푚푔/푚3] size fraction, and 65% in the D [63-500 μm: 13920푚푔/푚3] size fraction (Figures 10 and 11). In Buzzards Bay, the percentage of C size fraction for microplastics had a range of 7.69% - 78.78%, with a mean of 37.57%; the D size fraction had a range of 7.87% - 91.35%, and a mean of 52.41% (Figure 12).

On Nantucket Sound Beaches, the smallest (63-500 μm) size fraction dominated. Mashpee Town Beach had 96% of microplastics in the D size fraction, with 9740푚푔/푚3; Seagull Beach had 81% of its microplastics in the D size fraction; Ridgevale Beach had 60% of microplastics in the D size fraction (400 푚푔/푚3), 9% in the C size fraction (60푚푔/푚3), and 30% in the B size fraction (200푚푔/푚3) (Figure 10 and 11). In Nantucket Sound, the D size fraction had a percentage variability range between 2.29% - 95.68%, with a mean of 7.98% (Figure 25). It should be noted that for Seagull Beach and Ridgevale Beach, that plastic pieces were recovered in the samples, however were larger than 5mm so were eliminated to avoid data skewing due to their greater mass.

Atlantic Ocean microplastics were dominated by the smallest size fraction (63-500 μm) as well as the B size fraction (1-5 mm). Lighthouse beach had 85% of microplastics in the D size fraction (11780푚푔/푚3); Longnook Beach had 86% of microplastics in the D size fraction; and Race Point Beach had 71% of microplastics in the B size fraction (100푚푔/푚3) (Figure 10 and Microplastic pollution on Cape Cod beaches 9

11). Along Atlantic Ocean facing beaches, the microplastics B size fraction percentage had a range between 2.5% - 89.47%, with a mean value of 71.42%; the D size fraction had a range between 0% - 84%, and a mean value of 28.57% (Figure 12). Cape Cod Bay the lowest overall abundance of microplastics and the most variability, with the B and C size fractions dominating. Scusset Beach had 55% of microplastics in the D size fraction (220푚푔/푚3) and 45% in the B size fraction (180푚푔/푚3); Sandy Neck Beach had 68% of microplastics in the D size fraction (5000푚푔/푚3) and 28% in the B size fraction (2080푚푔/푚3); Corn Hill beach had 79% of microplastics in the B size fraction (4400푚푔/푚3) and 21% in the D size fraction (1160푚푔/푚3) (Figure 10 and 11).

Cape Cod Bay had the most variability in its D size fraction, with a percentage range between 33.33% - 72.5%, and a mean value of 68.11% (Figure 12). The smallest microplastics size fractions dominated Cape Cod beaches.

Scaling up: Microplastic abundance is magnified depending on beach size length. Figure 32 displays the modeled abundance of microplastics (g) at the high tide line, assuming the abundance of microplastics is consistent throughout. Beach lengths (Table 2) were obtained from ArcGIS by measuring the length of the twelve beaches at the high tide (Figure 16). Based on this model, Sandy Neck Beach, with a length of 9,461 m would have the greatest abundance of microplastics (69.45 g), Seagull Beach (1,350.1 m) would have the second greatest abundance of microplastics (47.05 g), Mashpee Town Beach (2,774.3 m) would have the third largest abundance at 28.24 g. Race Point Beach (8,657.1 m) would have the lowest abundance of microplastics at 1.21 g along with Scusset Beach (2,686 m ) with an abundance of 1.77 g. The two largest beaches sampled were Sandy Neck Beach and Race Point Beach (Table 2).

DISCUSSION

Plastics are a non-biodegradable material that have become an increasing environmental pollutant. Microplastics are ubiquitous throughout the marine environment and regarded as a contaminant of global concern (Coppock et al., 2017) Microplastics are the result of the persistent use, discard and breaking down of larger plastic debris. This study aimed to quantify the distribution of microplastics on Cape Cod beaches. The results of this study suggest that microplastics are ubiquitous on the coastal systems of Cape Cod and are a result of local and regional pollution sources. On Cape Cod beaches, the smallest size fraction of microplastics (63- 500 μm) was found to be the most abundant across all four Cape Cod coastal zones.

The results of this research project demonstrate the spatial heterogeneity of microplastic pollution on Cape Cod beaches. Factors that would influence the abundance of these microplastics on Cape Cod beaches include local and regional pollution sources from varied land use as well as different hydrodynamic sources. On the coast of Buzzards Bay, medium sand Microplastic pollution on Cape Cod beaches 10 beaches were dominated by the smallest microplastic size fraction (63-500 μm). Buzzards Bay is the most landlocked coast on Cape Cod, with currents influenced most by the wind (Sankaranarayanan 2007); this could provide evidence for why the greatest abundance of microplastics were found along its shores, as microplastics carried by the currents only have one way in and out of the bay. Additionally, the western end of Cape Cod is populated year-round, so it can be inferred that regional as well as local sources of plastic pollution play a role in the contamination of beaches along Buzzards Bay; this also provides evidence that the large microplastic abundance may be sources from runoff within the more densely populated Buzzards Bay watershed. Similarly, the Nantucket Sound and Atlantic Ocean shorelines consisted of medium sand beaches dominated by the smallest microplastic size fraction (63-500 μm). Nantucket Sound had the second highest abundance of microplastics. Nantucket Sound is the most variable in its hydrodynamic sources, which could account for its highly variable beach characteristics and abundance of microplastics (Limeburner et al., 1982). The second way microplastics enter the marine environment is through direct introduction through runoff. Interestingly, Nantucket Sound had a large number of plastic particles larger than 5 mm, which suggests contamination by local sources, more so than regional; the evidence for this comes from an evaluation of the land uses surrounding the beaches, as the two beaches with macroplastics were close to medium sized residential areas.

The Atlantic Ocean overall had the lowest abundance of microplastics, I hypothesize this is due to the larger hydrodynamic sources and exposure to the ocean, which would suggest low resonance time for microplastics on the shoreline. Lighthouse Beach, had the highest abundance of microplastics in this zone, and was also the beach with higher residential and commercial space nearby. Cape Cod Bay was more variable with overall low plastic abundance, but still dominated by the smallest microplastic size fractions. As a whole, the evidence of this study suggests that the majority of microplastics found on Cape Cod beaches are a result of plastic that has been in the environment for a substantial period of time, as one of the sources of microplastics are the result of the weathering breakdown of macroplastic debris (Andrady 2011). Smaller microplastic fraction sizes provide evidence that the microplastics found on Cape Cod beaches are being transported through the environment via the currents surrounding Cape Cod.

Additionally, the results indicate there is a relationship between grain size distribution and microplastic abundance, the finer sand beaches had the greater abundances of microplastics (Figure 13). This corroborates evidence from one study, (Browne et. al 2011) that noted that if spatial patterns of microplastics result primarily from the transportation of natural particles by water currents, then the shores that accumulate smaller sized particles of sediment should accumulate more microplastics. Therefore, I found that understanding beach characteristics is very important in interpreting the abundance of microplastics on coastal systems. Additionally, beach evidence can be linked with coastal erosional patterns, beaches with larger grain sizes would be a result of higher erosion and finer grain sizes would suggest less erosion occurring. Microplastic pollution on Cape Cod beaches 11

Beach size is also important to consider when assessing the magnitude of microplastic contamination. The size of the beach can magnify the abundance of microplastics. Assuming that the abundance of microplastics is consistent throughout the entirety of the beach, this study estimates the highest abundances of microplastic in the larger beaches of Cape Cod Bay. This highlights that the larger the beach area, the greater the abundance of microplastics overall, unless the beach had a low abundance of microplastics prior to scaling it up to beach level. This evidence is useful in predicting which coastal systems may be more at risk to higher levels of contamination.

Overall, the abundance of microplastics on Cape Cod beaches is highly variable, with the evidence suggesting that microplastic contamination is a result of regional pollution. Furthermore, the variability of microplastics in the northeast Atlantic Ocean is consistent with variability of microplastic concentrations on the coast (Law et al., 2010); microplastics were collected in the northwestern Atlantic Ocean via surface plankton net tows from 1986 to 2008 and found that microplastic concentrations surrounding Cape Cod were highly variable. Cape Cod is one of the many environments exhibiting microplastic contamination, there is a need for further study of the extent to which microplastic pollution is affecting the health of organisms and the structure of ecosystems not only on Cape Cod, but globally. It is critical to understand the sources of microplastic contamination, not only on a local scale but one that is regional, and even globally. The environment is a series of fluid systems, constantly changing and influenced by the dynamics of neighboring systems.

CONCLUSIONS

The results of this study indicate that microplastics are ubiquitous on the coastal systems of Cape Cod and are a result of local and regional pollution sources, as well as subject to variable spatial distribution due to deposition by different hydrodynamic sources. On Cape Cod beaches, the smallest size fraction of microplastics (63-500 μm) was found to be the most abundant across all four Cape Cod coastal zones.

ACKNOWLEDGEMENTS

I would like to extend my sincerest gratitude to The Marine Biological Laboratory, Semester in Environmental Science Program, faculty, staff, project mentors: Rut Pedrosa Pamies, JC Weber & Maureen Conte, my student collaborator: Casey Beidelman and fellow SES students and TAs.

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FIGURES, GRAPHS AND TABLES

Buzzards Nantucket Atlantic Cape Cod Bay Sound Ocean Bay Magansett Mashpee Lighthouse Scusset Beach Beach Town Beach Beach Megansett Seagull Beach Longnook Sandy Neck Beach Beach beach Chapoquoit Ridgevale Race Point Corn Hill Beach Beach Beach Beach

Table 1. List of the twelve field sites where coastal sediment samples were collected for microplastic analysis.

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Table 2. Field sampling sites and their approximate beach lengths (taken using ArcGIS http://www.arcgis.com/home/webmap/viewer.html?webmap=b5a0a1aa9bd04895abc24ac214a91 478&extent=) measured at the high tide line. Includes summary of local land use information provided by ArcGIS and Google satellite information.

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Figure 1. Map of Cape Cod and observed/ modeled currents. (Sources: Lermusiaux et al. 2001; Beardsley et al. 1997; Camp et al. 1990; Haight 1942).

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Figure 2. Map breaking down the four zones on Cape Cod and the corresponding beaches in which sediment was collected for microplastic analysis. (Sources: Lermusiaux et al. 2001; Beardsley et al. 1997; Camp et al. 1990; Haight 1942)

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Figure 3. Photographs of microplastics separated from coastal beach sediment collected on various Cape Cod beaches.

Figure 4. Photographs of microplastics separated from coastal beach sediment collected on various Cape Cod beaches. Microplastic pollution on Cape Cod beaches 17

Figure 5. Survey photographs taken during field work on Cape Cod. Top: Left to right; Megansett Beach, New Silver Beach, Chapoquoit Beach, Lighthouse Beach, Longnook Beach, Race Point Beach Bottom: Left to right; Mashpee Town Beach, Seagull Beach, Ridgedale Beach, Scusset Beach, Sandy Neck Beach, Corn Hill Beach. Microplastic pollution on Cape Cod beaches 18

Figure 6. Satellite Images of field sampling sites on Cape Cod, depicting beaches and surrounding areas for assessing potential local pollution sources. Left to right; Megansett Beach, New Silver Beach, Chapoquoit Beach, Lighthouse Beach, Longnook Beach, Race Point Beach (underneath) Bottom: Left to right; Mashpee Town Beach, Seagull Beach, Ridgedale Beach (underneath), Scusset Beach, Sandy Neck Beach, Corn Hill Beach.

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Figure 7. Diagram of sediment collection field methods.

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Grain Size Distribution:

Figure 8. Comparison of grain size distribution percentages across the three beaches on the coast of Buzzards Bay (A), Nantucket Sound (B), Atlantic Ocean (C) and Cape Cod Bay (D) Cape Cod, MA. Gravel size fraction = >5mm, coarse sand = 1-5mm, medium sand = 500 µm – 1 mm, fine sand = 63-500 µm, and silt and clay = <63 µm.

Microplastic pollution on Cape Cod beaches 21

Figure 9. Box plot displaying variability in grain size distribution percentages for Buzzards Bay (A), Nantucket Sound (B), Atlantic Ocean (C) and Cape Cod Bay (D) Cape Cod, MA. Coarse sand = 1-5mm, medium sand = 500 µm – 1 mm, fine sand = 63-500 µm, and silt and clay = <63 µm. *Note: large size fraction >5mm is excluded. Box and whisper plot display the range (highest and lowest value of the box), the mean (line with circle), and the median (‘x’).

Microplastic pollution on Cape Cod beaches 22

Microplastic Abundance:

Figure 10. Comparison of microplastic abundance (mg/푚3) across the three beaches on the coast of Buzzards Bay (A), Nantucket Sound (B), Atlantic Ocean (C) and Cape Cod Bay (D) Cape Cod, MA. Size fraction A = >5mm, B = 1-5 mm, C = 500 µm-1mm, D = 63-500 µm

Microplastic pollution on Cape Cod beaches 23

Figure 11. Comparison of microplastics abundance percentages at the four different size fractions across the three beaches on the coast of Buzzards Bay (A), Nantucket Sound (B), Atlantic Ocean (C) and Cape Cod Bay (D) Cape Cod, MA. Note: largest size fraction (>5mm was removed). Size fraction A = >5mm, B = 1-5 mm, C = 500 µm-1mm, D = 63-500 µm.

Microplastic pollution on Cape Cod beaches 24

Figure 12. Box plot displaying variability in microplastic size fraction percentages for Buzzards Bay (A), Nantucket Sound (B), Atlantic Ocean (C) and Cape Cod Bay (D) Cape Cod, MA. Size fraction A = >5mm, B = 1-5 mm, C = 500 µm-1mm, D = 63-500 µm. Box and whisper plot display the range (highest and lowest value of the box), the mean (line with circle), and the median (‘x’).

Microplastic pollution on Cape Cod beaches 25

Figure 13. Comparison between the percentage of course sand (A) and medium course sand (B) and microplastic total abundance (g) at each of the four Cape Cod zones. BB = Buzzards Bay (blue circle), NS = Nantucket Sound (yellow ‘x’), ATO = Atlantic Ocean (yellow square), and CCB = Cape Cod Bay (red triangle).

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Figure 14. Comparison of total microplastic abundance (푔/푚3)at each of the four zones on Cape Cod.

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Figure 15. Comparison of total microplastic abundance (푔/푚3) in the smallest size fractions (<5mm) at each of the four zones on Cape Cod. Microplastic pollution on Cape Cod beaches 28

Figure 16. Model depicting the total amount of microplastics at the high tide line, scaled up to the beaches size, on all twelve Caper Cod beaches. Model assumes plastic abundances are consistent throughout the high tide line. (Beach lengths obtained from ArcGIS - Table 2)

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Figure 17. Map displaying the abundance of microplastics in the northeast Atlantic Ocean (pieces/km2), with a focus on Cape Cod (Modified from Law et al., 2010).

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