Marine Litter Vital Graphics

DEFINITIONS

Which plastics oat and which sink in seawater?

Bottle caps (Polypropylene, PP)

Plastic bags (Polyethylene, PE)

Floats (Polystyrene, EPS)

0.92

0.95

1,00

1.01

Seawater density

Fishing nets (Polyamide or Nylon)

1,05

1.09

1,10

Containers (Polystyrene, PS)

1.15

1,15

Density Grams per cubic centimetre

1,20

Cigarette lters (Cellulose acetate)

Soft drink bottles (Polyethylene terephtalate, PET)

Textiles (Polyesther resin)

1.24

1,25

1,30

1.30

Plastic lm (Polyvinyl chloride, PVC)

1.35

1,35

1.39

Source: GESAMP, Sources, fate and e ects of microplastics in the marine environment: A global assessment, 2015

In addition to polymers, additives such as flame retardants (e.g. polybrominated diphenyl ethers), and plasticisers (e.g. phthalates) are also mixed into synthetic materials to increase their flexibility, transparency, durability, and longevity. Some of these substances, present in most plastic objects found in the marine environment, are known to be toxic to marine organisms and to humans (Rochman et al., 2015). The plastic used in the manufacture of an object depends on its intended use. The type of plastic will determine the ease with which an object can be recycled. Some plastics cannot be recycled, which means they enter the waste management system. If they make it into the marine environment, plastics that are less dense than sea water will float at the surface. Floating objects can be readily transported by wind, waves and surface currents and become widely dispersed across the ocean. Plastics that are denser than seawaterwill sink to the sea floor and accumulate or be redistributed, along with other sedimentary particles, through bottom sedimentary processes.

fishing nets and lost cargo containers. Moderate sized objects less than one metre long might include plastic bags, soda bottles or milk containers. Small spheres of expanded polystyrene are on the scale of millimetres. Micrometre-sized plastic beads are present in cosmetic products and synthetic cloth fibres or are derived from fragments broken down from larger plastic items. There has recently been a noticeable increase in concern about the implications of pollution by small sized debris, especially wheremade up of plastic. The term“microplastic” has been introduced to describe small plastic debris commonly less than 5 mm in diameter. The concern about microplastic pollution is due to its ubiquitous presence in the marine environment. Yet it is difficult to assess its quantity because of the small size of the particles and the fact that little is known about the chemical reactions and the extent of its incorporation into the trophic chain. Investigations are also being conducted into the implications of organisms’ exposure to and intake of plastic nanoparticles, particles smaller than 1 micron. With such limited knowledge of the ultimate ecological effects of microplastics and nanoplastics, there are concerns over their potential impacts at the level of ecosystems.

Marine litter comes in all sizes. Large objects may be tens of metres in length, such as pieces of wrecked vessels, lost

Marine Litter Vital Graphics

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