Table of Contents Table of Contents
Previous Page  37 / 60 Next Page
Show Menu
Previous Page 37 / 60 Next Page
Page Background


Marine Litter

Vital Graphics


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