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Why do plastic wastes accumulate in ocean gyres?
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plastic pollution
A volunteer collecting plastic nurdles (pellets less than 0.2 inch [0.5 centimeter] in diameter) at Barreiras Beach, Corrubedo, Spain.
Plastic waste accumulates in ocean gyres primarily due to the large-scale, wind-driven ocean currents that circulate within these regions.12
These accumulations occur in five major subtropical gyres located at Earth's midlatitudes, which cover approximately 40 percent of the world's oceans. The process functions as follows:2
- Circulation Patterns: Driven by atmospheric circulation and the Coriolis force, these gyres create massive, rotating systemsâclockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere.134
- Trapping Mechanism: As surface currents transport debris from coastal and terrestrial sources, the rotational movement of the gyre draws in and traps solid matter, including plastics.12
- Concentration: Over time, these zones become "garbage patches" where plastic waste, ranging from larger items to microplastics, becomes highly concentrated.12
Because the ocean is downstream from nearly every terrestrial location, it acts as a primary receiving body for improperly discarded plastic litter, which is then funneled into these stable, rotating oceanic hubs.2