lable at ScienceDirect

Environmental Pollution 207 (2015) 190e195

Contents lists avai

Environmental Pollution

journal homepage: www.elsevier .com/locate/envpol

Microplastics in commercial bivalves from China

Jiana Li a, Dongqi Yang a, Lan Li b, Khalida Jabeen a, Huahong Shi a, *

a State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200062, Chinab Research Center for Analysis and Measurement, Donghua University, Shanghai 201620, China

a r t i c l e i n f o

Article history:Received 15 April 2015Received in revised form18 August 2015Accepted 6 September 2015Available online xxx

Keywords:MicroplasticBivalvesSeafoodHuman health

* Corresponding author.E-mail address: hhshi@des.ecnu.edu.cn (H. Shi).

http://dx.doi.org/10.1016/j.envpol.2015.09.0180269-7491/© 2015 Elsevier Ltd. All rights reserved.

a b s t r a c t

We investigated microplastic pollution in 9 commercial bivalves from a fishery market in China. Multipletypes of microplastics, including fibers, fragments and pellets, occurred in the tissue of all bivalves. Thenumber of total microplastics varied from 2.1 to 10.5 items/g and from 4.3 to 57.2 items/individual forbivalves. Scapharca subcrenata contained on average 10.5 items/g and exhibited the highest levels ofmicroplastics by weight. Fibers were the most common microplastics and consisted of more than half ofthe total microplastics in each of the 8 species. In Alectryonella plicatula, pellets accounted for 60% of thetotal microplastics. The most common size class was less than 250 mm and accounted for 33e84% of thetotal microplastics calculated by species. Our results suggest that microplastic pollution was widespreadand exhibited a relatively high level in commercial bivalves from China. More intensive investigations onmicroplastics should be conducted in seafood.

© 2015 Elsevier Ltd. All rights reserved.

1. Introduction

Microplastics, defined as plastic materials or fragments <5 mm,are most likely the most numerically abundant plastic debris itemsin the ocean today (Law and Thompson, 2014). The quantities ofmicroplastics will inevitably increase due to the degradation oflarge, single plastic items, ultimately breaking down into millionsof microplastic pieces (Cozar et al., 2014). Therefore, concernregarding plastic pollution has focused on sources, fate andecological effects of microplastic particles in recent years (Coleet al., 2015; Hall et al., 2015; Rocha-Santos and Duarte, 2015).

One of the primary environmental risks associated withmicroplastics is their bioavailability for marine organisms (Wrightet al., 2013; Desforges et al., 2015). Bivalves are of particular in-terest because their extensive filter-feeding activity exposes themdirectly to microplastics present in the water column. Severalin vivo studies have suggested that microplastics may translocatefrom the gut cavity to the blood stream, enter cells and cause sig-nificant effects on the tissue and on cellular levels in mussels(Browne et al., 2008; Von Moos Et Al., 2012). In addition, micro-plastics can adsorb pyrene and transfer it to exposed musselsMytilus galloprovincialis (Avio et al., 2015). Microplastics can evenbe transferred frommussels to crabs through the food chain, which

increases the concern for microplastic to reach higher trophic levelsincluding humans (Farrell and Nelson, 2013; Watts et al., 2014).

Microplastics have also been found in farmed and wild mussels(My. edulis) and oysters (Crassostrea gigas) used for seafood(Mathalon and Hill, 2014; Van Cauwenberghe and Janssen, 2014). Aprevious study showed that microplastics were present in allmussels collected from six locations along the French-Belgian-Dutch coastline (Van Cauwenberghe et al., 2015). Uptake ofmicroplastic has ever been used as one of the marine health statusparameters in mussels (De Witte et al., 2014).

A recent study suggests that globally China has the greatestplastic waste originating from the land and deposited into theocean (Jambeck et al., 2015). High levels of microplastics have alsobeen observed in surface waters of the Yantgze Estuary and adja-cent waters (Zhao et al., 2014). Bivalves are widespread in thecoastal waters of China and are a popular seafood. In addition,humans have the habit of eating all of the soft parts of bivalveswhen consuming them as seafood. Therefore, humans mightexperience potential health risks when they consume bivalvespolluted by microplastics (Seltenrich, 2015).

In the present study, we collected 9 of the most commerciallypopular species of bivalves from a fishery market of Shanghai,China and the abundance and types of microplastics weremeasured. Our aims were to determine if the commercial bivalvesin China have been polluted by microplastics and to distinguish thedifferences of microplastic pollution among the various differentgenera.

J. Li et al. / Environmental Pollution 207 (2015) 190e195 191

2. Materials and methods

2.1. Sample collection

Nine species of marine bivalves were bought from the biggestfishery market of Shanghai, China, in November, 2014 (Table 1).These species were the most commercially popular bivalves andrepresent 9 genera, respectively. The species were collected fromfishery farms or wild environments along the coastal waters ofChina.

2.2. Quality control of analysis

One blank extraction group without tissue was performedsimultaneously to correct for the potential procedural contamina-tion. To avoid contamination, all of the liquid (freshwater, salt waterand hydrogen peroxide) was filtered with 1 mm filter paper prior touse. All of the containers and beakers were rinsed three times withfiltered water. The samples were immediately covered if they werenot in use. All of the experimental procedures were finished as soonas possible.

Fig. 1. Identification of microplastics with micro-Fourier Transformed Infrared Spec-troscope (m-FT-IR). The measurements in the figure were performed under the trans-mittance mode. The arrows indicate transparent spheres for m-FT-IR analysis (B).

2.3. Hydrogen peroxide treatment

The shell length and weight of each bivalve was first recorded.Next, the shells were opened, and the inner contents of 1e5 in-dividuals were emptied into a 1 L glass bottle with a height of35 cm. All of the same sample was placed in one bottle andregarded as a replicate, and six replicates were prepared for eachspecies. The tissue of each Patinopecten yessoensis was divided andput into three bottles due to its weight being the greatest, and theresults of three bottles were combined as one replicate in the end.Approximately 200 mL of 30% H2O2 was added to each bottle todigest the organic matter depending on the weight of the softtissue in each bottle. The bottles were covered and placed in anoscillation incubator at 65 C at 80 rpm for 24 h and then at roomtemperature for 24e48 h depending on the digestion effect of thesoft tissue.

2.4. Floatation and filtration with saline (NaCl) solution

A concentrated saline solution was prepared to separate themicroplastics from dissolved liquid of the soft tissue via floatation.Approximately 800 mL of filtered NaCl solution was added to eachbottle. The liquid was mixed and retained overnight. The overlyingwater was directly filtered over a 5 mm pore size, 47 mm diametercellulose nitrate membrane filter (Whatman AE98) using a vacuumsystem. Next, the filter was placed into clean petri dishes with acover for further analysis.

Table 1Length and weight of bivalves from a fishery market of China.

Genus Species Number Shell length (cm

Scapharca Sc. subcrenata 6 3.64 ± 0.16a

Tegillarca T. granosa 18 2.62 ± 0.21Mytilus My. galloprovincialis 18 4.65 ± 0.25Patinopecten P. yessoensis 6 8.92 ± 0.23Alectryonella A. plicatula 18 8.40 ± 0.58Sinonovacula Si. constricta 6 6.21 ± 0.45Ruditapes R. philippinarum 24 3.36 ± 0.21Meretrix Me. lusoria 18 3.49 ± 0.18Cyclina C. sinensis 30 2.82 ± 0.16

a Mean ± standard error (n ¼ 6e30).

2.5. Observation of microplastic

The filters were observed under a Carl Zeiss Discovery V8 Stereomicroscope (MicroImaging GmbH, G€ottingen, Germany), and im-ages were taken with an AxioCam digital camera. A visual assess-ment was applied to identify the types of microplastics according tothe physical characteristics of the particles. A number of commonand undeterminable particles were selected and verified with amicro-Fourier Transformed Infrared Spectroscope (m-FT-IR).

2.6. Verification of microplastics using m-FT-IR

The identification was conducted out with a m-FT-IR microscope(Thermo Nicolet iN10 MX). The transmittance mode was appliedfor transparent and semi-transparent particles and an attenuatedtotal-reflection mode was applied for opaque particles. The spec-trum rangewas set at 4000 to 675 cm�1 with a collection time of 3 sand 16 co-scans for each measurement. The spectral resolutionwas8 cm�1 for all of the samples, and the aperture size ranged from

) Shell weight (g/individual) Soft tissue weight (g/individual)

14.62 ± 1.54 4.43 ± 0.696.84 ± 0.67 1.29 ± 0.105.66 ± 1.40 1.79 ± 0.42

68.87 ± 0.79 24.80 ± 2.0735.27 ± 5.73 1.84 ± 0.3313.52 ± 2.74 7.53 ± 1.606.38 ± 1.37 2.21 ± 0.29

11.32 ± 1.45 2.33 ± 0.546.55 ± 1.48 1.19 ± 0.27

Fig. 2. Photographs of different types of microplastics in bivalves from a fishery market of China. The photographs were taken directly on the filter paper (AeH), and some specialmicroplastics were transferred to a hollow glass slide for photographs (I). The arrows indicate fibers (AeC), fragments (DeF) and pellets (GeI). Scale bar ¼ 100 mm.

J. Li et al. / Environmental Pollution 207 (2015) 190e195192

50 � 50 mm to 150 � 150 mm depending on the size of the particles.All of the spectra were later compared with the library (e.g.,Hummel Polymer and Additives and Polymer Laminate Films) toverify the polymer type.

3. Results

3.1. Identification of microplastics in bivalves with m-FT-IR

Some particles were selected and identified with m-FT-IR. Themost common plastic was polyethylene followed by polyethylenesterephthalate and polyamide (Fig. 1A). Several particles, whichwere previously identified as microplastics by visual observationunder the microscope, were demonstrated to be other materials,rather than microplastics using the m-FT-IR. A large amount ofuniform transparent spheres were found in Scapharca subcrenataand determined to be aluminum silicate based on the analysis oftheir spectra (Fig. 1B).

Fig. 3. Abundance of microplastics in bivalves from a fishery market of China. Six repli-cates were set for each species (n¼ 6), and 1e5 individuals were pooled as one replicate.

3.2. Types of microplastics in bivalves

Contamination with airborne microplastics was preventedduring handling the samples, and the procedural blanks only con-tained 0.50 ± 0.55 items/filter of microplastics. Multiple types ofmicroplastics, including fibers, fragments and pellets, occurred inthe tissue of bivalves (Fig. 2). The most diverse colors wereobserved in the fibers followed by the fragments. The most popularcolors were black, red, blue, white and transparent (Fig. 2AeF).Overall, the pellets were usually transparent and white (Fig. 2GeI).

Fig. 4. The composition of the different types of microplastics in bivalves from aChinese fishery market. Six replicates were set for each species (n ¼ 6), and 1e5 in-dividuals were pooled as one replicate.

J. Li et al. / Environmental Pollution 207 (2015) 190e195 193

3.3. Abundance of microplastics in bivalves

The number of total microplastics varied from 2.1 to 10.5 items/g(wet weight) and from 4.3 to 57.2 items/individual for bivalves(Fig. 3). Sc. subcrenata contained an average of 10.5 items/g andshowed the highest levels of microplastic contamination by weight(Fig. 3A). Patinopecten yessoensis showed the highest microplastics(57.2 items/individual) by the individual (Fig. 3B).

Fig. 5. The composition of the different size classes of microplastics in bivalves from afishery market of China.

Fibers were the most popular microplastics and consisted ofmore than half of the total microplastics in each of the 8 species(Fig. 4). Pellets were the least common in 6 species and were notobserved at all in Sinonovacula constricta or Tegillarca granosa.However, pellets accounted for 60% and were dominant in Alec-tryonella plicatula (Fig. 4H).

3.4. Size of microplastics in bivalves

The size of the microplastics ranged from 5 mm to 5 mm in thebodies of the bivalves that were examined. The microplastics lessthan 250 mm in size were the most common and consisted of33e84% of the total microplastics calculated by species (Fig. 5).

4. Discussion

4.1. Methods to isolate and analyze microplastics in bivalves

The ambiguous characteristics of non-plastics and plastics makeit difficult to accurately identify microplastics (Song et al., 2015).The analysis of microplastics from biota samples requires moreeffective separation and identification methods. Acid digestion hasoften been used to isolate microplastics from bivalves (Table 2).However, concentrated acid (e.g., HNO3) has a detrimental effect on(nylon) fibers and results in the total destruction of this type ofmicroplastic during extraction (Claessens et al., 2013).

In the present study, we used 30% H2O2 to digest the soft tissueof bivalves and observed many diverse types of microplasticsincluding rich fibers (Fig. 2). It is crucial to control the maximumweight of soft tissuewhen H2O2 is used. Toomuch soft tissue in onereplicate usually requires a longer digestion time and can evenrequire repetition of the digestion (Mathalon and Hill, 2014). Ourexperiments suggest that the addition of no more than 5 g of tissueand approximately 200 mL H2O2 in a 1 L bottle showed a gooddigestion effect.

In our present study, we successfully identified a large numberof uniform transparent spheres as aluminum silicate but notmicroplastics using m-FT-IR (Fig. 1B). The aluminum silicate parti-cles were also identified with scanning electron microscopy (SEM)analysis and thought to be derived from coal ash in the samplesfrom the Great Lakes (Eriksen et al., 2013). On the one hand, ourstudy suggests that the aluminum silicate particles could accu-mulate in biota. On the other hand, our study further confirms theimportance of conducting elemental analysis or chemical analysisof microplastics to avoid misidentification (Eriksen et al., 2013;Song et al., 2015).

4.2. Comparison of microplastic pollution in bivalves

We found that microplastic pollution was widespread andshowed great variation between the species of bivalves collectedfrom the Chinese fishery market (Fig. 3). Compared to the abun-dance reported in a previous study (Table 2), the levels of micro-plastics were approximately one order of magnitude higher thanthose reported in mussels and oysters with the exception of that inMathalon and Hill (2014), in which the highest concentrationreached 178 microfibers per mussel. The level of our results mightbe similar to that in Mathalon and Hill (2014) if the contaminationof airborne microplastics is excluded from their results. The highconcentrations of microplastics in bivalves should be closely relatedto the plastic contamination of the living environments of bivalves.In recent years, severe microplastic pollution has been reported inthe water column and sediments along the coastal waters of China(Zhao et al., 2014; Fok and Cheung, 2015; Qiu et al., 2015).

In previous studies, different terms were used to describe the

Table 2Comparison of microplastic pollution in bivalves in the present study with those in previous studies.

Species and sources Treatmentmethod

Identification method Types ofmicroplastics

Levels ofmicroplastics

References

Mytilus edulisCanada 30% H2O2 Visual identification under the microscope Fibers 34e178 items/

individualMathalon and Hill, 2014

Belgium HNO3:HClO4 Visual identification and verified with a hot needle Fibers 0.26e0.51 items/g De Witte et al., 2014Germany (North Sea) 69% HNO3 Visual identification and micro-Raman spectrometer Particles without

observed fibers0.36 items/g Van Cauwenberghe

and Janssen, 2014French, Belgian and

Dutch North Sea69% HNO3 Visual identification and verified with a

micro-Raman spectrometerParticles and allfibers omitted

0.2e0.3 items/g Van Cauwenberghe et al., 2015

Crassostrea gigasFrance (Atlantic Ocean) 69% HNO3 Visual identification and verified with a

micro-Raman spectrometerParticles 0.47 items/g Van Cauwenberghe

and Janssen, 2014Nine bivalvesA fishery market

in China30% H2O2 Visual identification and verified with an m-FT-IR Fibers, fragments

and pellets2.1e10.5 items/g In this study

J. Li et al. / Environmental Pollution 207 (2015) 190e195194

morphology of microplastics (Table 2). To avoid a misunder-standing, we used “items” rather than “particles” as the unit todescribe the number of all of the types of microplastics in this study(Fig. 2). Our results suggest that fibers are themost common type ofmicroplastics (Fig. 4), which was in accordance with results re-ported by Mathalon and Hill (2014) and De Witte et al. (2014). Fi-bers are not reported in Van Cauwenberghe and Janssen, (2014);Van Cauwenberghe et al. (2015) due to the detrimental effect ofconcentrated HNO3 on fibers during the isolation process ofmicroplastics. Most bivalves in the markets of China come fromfishery farms because of the high demand. Significantly moremicroplastics were observed in farmed mussels compared to wildmussels, which might be due to the fact that the farmed musselsgrow on polypropylene plastic lines (Mathalon and Hill, 2014).

It was interesting to observe a high concentration of sphericalmicroplastics in oysters (Fig. 4). Though the spherical plastic particlescan accumulate in the hemolymph of mussels after controlled labexposure (Browne et al., 2008; Von Moos Et Al., 2012), the uptake ofplasticfilmsand spherical or granularmicroplastics fromtheir naturalenvironment has not been observed in mussels in previous studies(DeWitte et al., 2014). It iswidelyaccepted that spherical andgranularparticles are most likely removed from the digestive tract, where theegestion of synthetic fibers appears to be delayed. Our results suggestthat granular particles can also accumulate at a high concentration insome bivalves such as oysters. Further studies should be conducted todetermine if features of a species or the pollution level of the sur-rounding environment leads to such specificity in oysters.

4.3. The risk of microplastics to the ecosystem and humans

Microplastics are a particular threat not only due to their sizebut also for their capacity to adsorb persistent organic pollutants(Engler, 2012). The adsorbed pollutants can be transferred frommicroplastics into the body of bivalves and result in toxicologicalrisk (Avio et al., 2005). Our study further confirms that microplasticpollution is widespread in bivalves and that bivalves can be used asindicators of microplastic pollution in coastal waters (Table 2).

The constituents of plastics and the organic pollutants that theysorb may ultimately be transferred into humans through the con-sumption of seafood. Therefore, the presence of marine micro-plastics in commercial bivalves can pose a threat to food safety(Seltenrich, 2015). The annual dietary exposure for Europeanshellfish consumers is estimated to reach 11,000 microplastics peryear (Van Cauwenberghe and Janssen, 2014). Our results suggeststhat the annual dietary exposure for Chinese shellfish consumersmight be one order of magnitude higher than that if they have thesame consumption of shellfish as European consumers because

more microplastics were found in the bivalves from Chinese fisherymarkets (Van Cauwenberghe and Janssen, 2014).

Nevertheless, due to the different calculation methods, it is stillhighly difficult to compare the levels and risks of microplasticpollution between the different studies (Table 2). Therefore, uni-form methods should be first developed to isolate and identifymicroplastics in bivalves, and uniform terms and units should alsobe used to present the abundance and types of microplastics. Due towidespread microplastics in seawater and bivalves, intensive in-vestigations are needed in commercial bivalves from more fisherymarkets. Several comprehensive models are also needed to predi-cate the toxicological risk for bivalves themselves and humans dueto the complex interactions between microplastics, pollutants andorganisms (Avio et al., 2015).

5. Conclusions

Our results suggest that microplastic pollution was widespreadand showed relatively high levels in the commercial bivalves fromthe investigated fishery market of China. The abundance and typesof microplastics exhibited great variation among species. Our studyhighlighted that a uniform method should be developed to isolateand identify microplastics in bivalves and that intensive in-vestigations on microplastic pollution should be conducted inseafood covering more fishery markets. In addition, our studyindicated that microplastic was widespread in seafood, such asshellfish, representing potential a risk for human health.

Acknowledgments

This work was supported by grants from the Natural ScienceFoundation of China (41571467) and the open funds of State KeyLaboratory of Estuarine and Coastal Research (SKLEC-KF201405).

References

Avio, C.G., Gorbi, S., Milan, M., Benedetti, M., Fattorini, D., D'Errico, G., Pauletto, M.,Bargelloni, L., Regoli, F., 2015. Pollutants bioavailability and toxicological riskfrom microplastics to marine mussels. Environ. Pollut. 198, 211e222.

Browne, M.A., Dissanayake, A., Galloway, T.S., Lowe, D.M., Thompson, R.C., 2008.Ingested microscopic plastic translocates to the circulatory system of themussel, Mytilus edulis (L.). Environ. Sci. Technol. 42 (13), 5026e5031.

Claessens, M., Van Cauwenberghe, L., Vandegehuchte, M.B., Janssen, C.R., 2013. Newtechniques for the detection of microplastics in sediments and filed collectedorganisms. Mar. Pollut. Bull. 70, 227e233.

Cole, M., Lindeque, P., Fileman, E., Halsband, C., Galloway, T.S., 2015. The impact ofpolystyrene microplastics on feeding, function and fecundity in the marinecopepod Calanus helgolandicus. Environ. Sci. Technol. 49, 1130e1137.

Cozar, A., Echevarria, F., Gonzalez-Gordillo, J.I., Irigoien, X., Ubeda, B., Hernandez-Leon, S., Palma, A.T., Navarro, S., García-de-Lomas, J., Ruiz, A., Fernandez-de-

J. Li et al. / Environmental Pollution 207 (2015) 190e195 195

Puelles, M.L., Duarte, C.M., 2014. Plastic debris in the open sea. Proc. Natl. Acad.Sci. U. S. A. 111 (28), 10239e10244.

De Witte, B., Devriese, L., Bekaert, K., Hoffman, S., Vandermeersch, G., Cooreman, K.,Robbens, J., 2014. Quality assessment of the blue mussel (Mytilus edulis):comparison between commercial and wild types. Mar. Pollut. Bull. 85 (1),146e155.

Desforges, J.W., Galbraith, M., Ross, P.S., 2015. Ingestion of microplastics byzooplankton in the Northeast Pacific Ocean. Arch. Environ. Contam. Toxicol.http://dx.doi.org/10.1007/s00244-015-0172-5.

Engler, R.E., 2012. The complex interaction between marine debris and toxicchemicals in the ocean. Environ. Sci. Technol. 46, 12302e12315.

Eriksen, M., Mason, S., Wilson, S., Box, C., Zellers, A., Edwards, W., Farley, H.,Amato, S., 2013. Microplastic pollution in the surface waters of the LaurentianGreat Lakes. Mar. Pollut. Bull. 77, 177e182.

Farrell, P., Nelson, K., 2013. Trophic level transfer of microplastic: Mytilus edulis (L.)to Carcinus maenas (L.). Environ. Pollut. 177, 1e3.

Fok, L., Cheung, P.K., 2015. Hong Kong at the Pearl River Estuary: a hotspot ofmicroplastic pollution. Mar. Pollut. Bull. http://dx.doi.org/10.1016/j.marpolbul.2015.07.050.

Hall, N.M., Berry, K.L.E., Rintoul, L., Hoogenboom, M.O., 2015. Microplastic ingestionby scleractinian corals. Mar. Biol. 162 (3), 725e732.

Jambeck, J.R., Geyer, R., Wilcox, C., Siegler, T.R., Perryman, M., Andrady, A.,Narayan, R., Law, K.L., 2015. Plastic waste inputs from land into the ocean.Science 347, 768e771.

Law, K.L., Thompson, R.C., 2014. Microplastic in the seas. Science 345 (6193),144e145.

Mathalon, A., Hill, P., 2014. Microplastic fibers in the intertidal ecosystem sur-rounding Halifax Harbor, Nova Scotia. Mar. Pollut. Bull. 81, 69e79.

Qiu, Q.X., Peng, J.P., Yu, X.B., Chen, F., Wang, J., Dong, F., 2015. Occurrence of

microplastics in the coastal marine environment: first observation on sedimentof China. Mar. Pollut. Bull. 98 (1-2), 274e280. http://dx.doi.org/10.1016/j.marpolbul.2015.07.028.

Rocha-Santos, T., Duarte, A.C., 2015. A critical overview of the analytical approachesto the occurrence, the fate and the behavior of microplastics in the environ-ment. TrAC Trends Anal. Chem. 65, 47e53.

Seltenrich, N., 2015. New link in the food chain? Marine plastic pollution andseafood safety. Environ. Health Perspect. 123 (2), A34eA41.

Song, Y.K., Hong, S.H., Jang, M., Han, G.M., Rani, M., Lee, J., Shim, W.J., 2015.A comparison of microscopic and spectroscopic identification methods foranalysis of microplastics in environmental samples. Mar. Pollut. Bull. 93,202e209.

Van Cauwenberghe, L., Claessens, M., Vandegehuchte, M.B., Janssen, C.R., 2015.Microplastics are taken up by mussels (Mytilus edulis) and lugworms (Arenicolamarina) living in natural habitats. Environ. Pollut. 199, 10e17.

Van Cauwenberghe, L., Janssen, C.R., 2014. Microplastics in bivalves cultured forhuman consumption. Environ. Pollut. 193, 65e70.

Von Moos, N., Burkhart-Holm, P., Kohler, A., 2012. Uptake and effects of micro-plastics on cells and tissue of the blue mussel Mytilus edulis L. after an exper-imental exposure. Environ. Sci. Technol. 46, 11327e11335.

Watts, A.J.R., Lewis, C., Goodhead, R.M., Beckett, S.J., Moger, J., Tyler, C.R.,Galloway, T.S., 2014. Uptake and retention of microplastics by the shore crabCarcinus manenas. Environ. Sci. Technol. 48 (15), 8823e8830.

Wright, S.L., Thompson, R.C., Galloway, T.S., 2013. The physical impacts of micro-plastics on marine organisms: a review. Environ. Pollut. 178, 483e492.

Zhao, S.Y., Zhu, L.X., Wang, T., Li, D.J., 2014. Suspended microplastics in the surfacewater of the Yangtze Estuary system, China: first observations on occurrence,distribution. Mar. Pollut. Bull. 86 (1e2), 562e568.