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How have microplastics reached deep ocean trenches and the ocean floor?
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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.
Microplastics reach the deepest parts of the ocean, including deep-sea trenches and the ocean floor, through several environmental processes.
While much plastic debris initially accumulates in surface waters and subtropical gyres, these materials eventually break down into smaller particles through weathering caused by sunlight, wave action, and wind abrasion. Once these microplastics are formed, they are transported to the seafloor and deep-ocean environments via the following mechanisms:12
- Marine Snow: Organic aggregates known as marine snowâwhich consist of mucus, cells, and other debrisâsink from the upper layers of the ocean to the floor. Microplastics can adhere to these structures, effectively hitching a ride as the material descends to the depths.3
- Deep-Sea Currents: The movement of deep-ocean currents plays a significant role in distributing microplastics, often concentrating them into "hot spots" on the ocean floor.1
- Biological Transport: Microplastics are ingested by a wide variety of marine species, including zooplankton and other small animals. As these organisms move through the water column or are consumed by predators, the plastic particles are integrated into the marine food webs and eventually deposited in deep-sea habitats.12