37 / 60
37
Marine Litter
Vital Graphics
GEOGRAPHICAL DISTRIBUTION
Debris found in a location at any moment in time will be a
mixture of locally-derived material plus particles that have
been transported by current, wind or wave. More than
half of the plastic that gets into the marine environment is
less dense than seawater, so until it acquires some ballast
(often from the accumulation of organic particles or marine
organisms), it floats. Once discarded, plastic can accumulate
close to its point of entry into the ocean or it can move long
distances, ending up in remote locations far away from its
entry point. This, combined with the slow degradation rate
of most plastic, means it can drift around the ocean for a long
time, becoming a true transboundary pollution problem.
Surface dispersion
Surface circulation in the ocean is dominated by five large
circular currents, called gyres – the North Atlantic, South
Atlantic, North Pacific, South Pacific and Indian Ocean
gyres. The currents around these gyres are primarily driven
by wind and are the major transport mechanism for the
dispersal of floating plastic debris (Barnes et al., 2009).
Discarded plastic moving around the ocean – on the surface, in the water column and on
the sea floor – sometimes comes to rest. The geographical distribution of marine plastic
debris is strongly influenced by the entry points and the different transport pathways,
which are in turn determined by the density of plastic debris coupled with prevailing
currents, wind and waves (Rech et al., 2014).
My litter your problem,
your litter my problem
Sample points used in the model South Paci c gyre South Atlantic gyre Indian Ocean gyre North Paci c gyre North Atlantic gyre Surface current Microplastic concentration* Kilograms per square kilometre Source: Van Sebille, E., et al., A global inventory of small oating plastic debris, IOP Publishing, 2015; Cooperative Institute for Meteorological Satellite Studies 10 0 Plastic currents A giant distribution system for marine plastics