Marine Litter Vital Graphics

Marine Litter

Vital Graphics

DEFINITIONS

Between 60 and 90 per cent – sometimes as much

as 100 per cent – of the litter that accumulates on

shorelines, the sea surface and the sea floor ismade up

of one or a combination of different plastic polymers.

The most common items, constituting over 80 per

cent of the litter stranded on beaches (Andrady, 2015)

are cigarette butts, bags, remains of fishing gear, and

food and beverage containers. Likewise, 90 per cent

of the litter collected from sea floor trawls is made up

of plastic (Derraik, 2002 and Galgani et al., 2015).

Plastics have only been mass-produced for around

60 years and therefore it is impossible to know with

certainty how long they last in the marine environment.

Most types of plastic are not biodegradable (Andrady

1994). In fact, they are extremely durable. This means

the majority of polymers manufactured today will

persist for decades and probably for centuries, if not

millennia. So-called degradable plastics may persist

for a long time because their degradation depends

on physical factors, such as exposure to light, oxygen

and temperature (Swift & Wiles 2004). Biodegradable

plastics also decompose through the mediation

of certain micro-organisms. Plastics labelled as

biodegradable, designed to undergo certain

degrees of degradation in landfills or in terrestrial

environments, may still persist for long periods

under marine conditions (Kyrikou & Briassoulis,

2007; UNEP, 2015). Full degradation of a plastic item

implies complete breakdown and decomposition

into water, carbon dioxide, methane and other non-

synthetic molecules. For the large majority of plastic

items, even if they disintegrate by breaking down into

smaller and smaller plastic debris under the influence

of weathering, the polymer itself may not necessarily

fully degrade into natural chemical compounds

or chemical elements under marine conditions

(Hopewell et al., 2009).