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The Mediterranean Plastic Soup: synthetic polymers in Mediterranean surface waters

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ABSTRACT

The Mediterranean Sea has been recently proposed as one of the most impacted regions of the world with regards to microplastics, however the polymeric composition of these floating particles is still largely unknown. Here we present the results of a large-scale survey of neustonic micro- and meso-plastics floating in Mediterranean waters, providing the first extensive characterization of their chemical identity as well as detailed information on their abundance and geographical distribution. All particles >700 μm collected in our samples were identified through FT-IR analysis (n = 4050 particles), shedding for the first time light on the polymeric diversity of this emerging pollutant. Sixteen different classes of synthetic materials were identified. Low-density polymers such as polyethylene and polypropylene were the most abundant compounds, followed by polyamides, plastic-based paints, polyvinyl chloride, polystyrene and polyvinyl alcohol. Less frequent polymers included polyethylene terephthalate, polyisoprene, poly(vinyl stearate), ethylene-vinyl acetate, polyepoxide, paraffin wax and polycaprolactone, a biodegradable polyester reported for the first time floating in off-shore waters. Geographical differences in sample composition were also observed, demonstrating sub-basin scale heterogeneity in plastics distribution and likely reflecting a complex interplay between pollution sources, sinks and residence times of different polymers at sea.

No MeSH data available.


Polymeric composition of all particles >700 μm characterized through ATR FT-IR analysis (n = 4,050 particles).Values are expressed in percentages. Identification of polymers was performed by comparison with a library of standard spectra and only polymers matching reference spectra for more than 60% were accepted.
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f2: Polymeric composition of all particles >700 μm characterized through ATR FT-IR analysis (n = 4,050 particles).Values are expressed in percentages. Identification of polymers was performed by comparison with a library of standard spectra and only polymers matching reference spectra for more than 60% were accepted.

Mentions: The polymeric identity of all particles >700 μm was verified through ATR FTIR (n = 4,050 particles). This subset was considered highly representative since it comprised 96.2% of the total weight of collected material. 16 different polymer typologies were identified (Fig. 2 and Fig. S3). Polyethylene (HD-PE and LD-PE) was the predominant form with an overall frequency of 52%, followed by polypropylene (PP) (16%) and synthetic paints (7.7%). Polyamides (PA) accounted for 4.7% of all characterized particles (excluding nylon which accounted alone for 1.9%), whereas polyvinyl chloride (PVC), polystyrene (PS) and polyvinyl alcohol (PVA) represented 2.6%, 2.8% and 1.2% respectively. Other less frequent polymers (<1%) included: poly(ethylene terephthalate) (PET), polyisoprene (synthetic rubber), poly(vinyl stearate) (PVS), ethylene-vinyl acetate (EVA) and cellulose acetate. Ten fragments of polycaprolactone, a biodegradable polymer, were found in seven different samples throughout the study area, while 201 fragments of epoxy resin (polyepoxide) were collected at a single location in the Balearic Sea. Similarly, several residues of paraffin wax were found exclusively in an off-shore sample in the Adriatic Sea. The molecular characterization also revealed a relatively low misidentification rate during visual sorting. Only 4.4% of all analyzed particles did not consist of plastic but were rather made of cotton, chitin, cellulose and other non-synthetic materials.


The Mediterranean Plastic Soup: synthetic polymers in Mediterranean surface waters
Polymeric composition of all particles >700 μm characterized through ATR FT-IR analysis (n = 4,050 particles).Values are expressed in percentages. Identification of polymers was performed by comparison with a library of standard spectra and only polymers matching reference spectra for more than 60% were accepted.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5120331&req=5

f2: Polymeric composition of all particles >700 μm characterized through ATR FT-IR analysis (n = 4,050 particles).Values are expressed in percentages. Identification of polymers was performed by comparison with a library of standard spectra and only polymers matching reference spectra for more than 60% were accepted.
Mentions: The polymeric identity of all particles >700 μm was verified through ATR FTIR (n = 4,050 particles). This subset was considered highly representative since it comprised 96.2% of the total weight of collected material. 16 different polymer typologies were identified (Fig. 2 and Fig. S3). Polyethylene (HD-PE and LD-PE) was the predominant form with an overall frequency of 52%, followed by polypropylene (PP) (16%) and synthetic paints (7.7%). Polyamides (PA) accounted for 4.7% of all characterized particles (excluding nylon which accounted alone for 1.9%), whereas polyvinyl chloride (PVC), polystyrene (PS) and polyvinyl alcohol (PVA) represented 2.6%, 2.8% and 1.2% respectively. Other less frequent polymers (<1%) included: poly(ethylene terephthalate) (PET), polyisoprene (synthetic rubber), poly(vinyl stearate) (PVS), ethylene-vinyl acetate (EVA) and cellulose acetate. Ten fragments of polycaprolactone, a biodegradable polymer, were found in seven different samples throughout the study area, while 201 fragments of epoxy resin (polyepoxide) were collected at a single location in the Balearic Sea. Similarly, several residues of paraffin wax were found exclusively in an off-shore sample in the Adriatic Sea. The molecular characterization also revealed a relatively low misidentification rate during visual sorting. Only 4.4% of all analyzed particles did not consist of plastic but were rather made of cotton, chitin, cellulose and other non-synthetic materials.

View Article: PubMed Central - PubMed

ABSTRACT

The Mediterranean Sea has been recently proposed as one of the most impacted regions of the world with regards to microplastics, however the polymeric composition of these floating particles is still largely unknown. Here we present the results of a large-scale survey of neustonic micro- and meso-plastics floating in Mediterranean waters, providing the first extensive characterization of their chemical identity as well as detailed information on their abundance and geographical distribution. All particles &gt;700&thinsp;&mu;m collected in our samples were identified through FT-IR analysis (n&thinsp;=&thinsp;4050 particles), shedding for the first time light on the polymeric diversity of this emerging pollutant. Sixteen different classes of synthetic materials were identified. Low-density polymers such as polyethylene and polypropylene were the most abundant compounds, followed by polyamides, plastic-based paints, polyvinyl chloride, polystyrene and polyvinyl alcohol. Less frequent polymers included polyethylene terephthalate, polyisoprene, poly(vinyl stearate), ethylene-vinyl acetate, polyepoxide, paraffin wax and polycaprolactone, a biodegradable polyester reported for the first time floating in off-shore waters. Geographical differences in sample composition were also observed, demonstrating sub-basin scale heterogeneity in plastics distribution and likely reflecting a complex interplay between pollution sources, sinks and residence times of different polymers at sea.

No MeSH data available.